Dragline Dictionary

Transcription

Dragline Dictionary

Dragline
Dictionary
Fourth Edition
2014
Dragline Dictionary
Fourth Edition
2014
PwC Mining Intelligence and
Benchmarking
Dragline Dictionary
PwC – Mining Intelligence and Benchmarking
T: +61 7 3257 5000
Email: graham.lumley@au.pwc.com
Dragline Dictionary
T: +61 7 3257 5000
Published by
PricewaterhouseCoopers, ABN 52 780 433 757
Riverside Centre, 123 Eagle Street, BRISBANE QLD 4000, GPO Box
150, BRISBANE QLD 4001
T: +61 7 3257 5000, F: +61 7 3257 5999, www.pwc.com.au
Liability limited by a scheme approved under Professional Standards
Legislation.
Copies available via download from
http://pwc.com.au/industry/energy-utilitiesmining/publications/dragline-dictionary.htm
Dragline Dictionary
T: +61 7 3257 5000
Dragline Dictionary
Fourth Edition
2014
In September 2013 PwC acquired the GBI Mining Intelligence business
(GBI). This is core to PwC’s Mining Intelligence business which
provides mining clients with asset benchmarking, productivity and
analytics services.
The First Edition of this dragline dictionary was started in 2005 by
GBI and first released in 2009. Many hundreds of hours were spent
sourcing photos and writing information.
Special recognition is made of the work of former GBI staff. Bevin
Horton in the early stage collated, travelled, photographed and
generally provided the foundations of this publication. More recently,
Jan Eike Sapper has shouldered the organising role and contributions
have been made by Trevor Trott. Graham Lumley started working on
the dictionary in early 2008. He added the productivity information
and reformatted it firstly to an A4 size and now the A5 size.
Eight years of work has gone into this fourth edition of the Dragline
Dictionary. A number of new entries have been made along with a
large number of photos and expanded writing on productivity issues.
There will always be variations in terminology across sites and it would
be impossible to capture all of these. We do however continue to
encourage your input. If there is something not included in this
dictionary please send us details and if possible photos. Send to:
Graham.Lumley@au.pwc.com
Wherever we are aware of the use of information and/or photos
provided by people outside PwC we will acknowledge this. If you wish
to discuss copyright please contact us.
Our aim is to produce the fifth Edition in 2015.
Dragline Dictionary
T: +61 7 3257 5000
PwC's Mining Intelligence and Benchmarking is a PwC
service offering.
In September 2013 PwC acquired the GBI Mining
Intelligence business. This is core to PwC’s consulting
business which provides mining clients with asset
benchmarking, productivity and analytics services.
PwC’s Mining Intelligence and Benchmarking service
offerings are appended to the end of this publication.
Dragline Dictionary
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Contents
3dDig 2000 – Dragline planning software .................................................................... 1
A Frame – The anchor for the boom and mast .............................................................3
AC – Alternating current .................................................................................................5
Access Stairs - Stairway for entry onto dragline ...........................................................6
Adaptor – Fitted to the noses on the bucket..................................................................7
Advance Bench – Bench ahead of the current dragline strip ......................................8
Air Compressor – Air supply for dragline functions ....................................................9
Air Conditioner Unit – Cool the cabin .........................................................................10
Air Dryers – Extract moisture from the compressed air.............................................11
Air Horns – Signal horns ............................................................................................... 12
Air Hoses – Deliver compressed air ............................................................................. 13
Air Receiver Tank – Holds the supply of compressed air .......................................... 14
Ancillary Equipment – Equipment that is used to support the dragline
operation. .................................................................................................................... 15
Angle of Repose – The degree of slope of resting overburden. .................................18
Anomalous Damage – Damage from an action outside standard dragline
operation..................................................................................................................... 20
Anteroom – Room behind the operators cabin........................................................... 21
Arch – (Bucket) ...............................................................................................................22
ASL – Actual Suspended Load ......................................................................................23
Availability (see also Maintenance) – A measure of the amount of time the
machine is available to operate (not down for maintenance) ...............................24
Backblading – Pushing material with the back of a full bucket ................................26
Bailing Mud – Digging mud ..........................................................................................27
Basket – The part of the bucket which carries the spoil............................................ 28
Batter – The slope of the high-wall or low-wall ..........................................................29
BCM/BCY – Bank Cubic Metre/Bank Cubic Yard..................................................... 30
Bench – The leveled area where the dragline sits and operates................................ 31
Bench End Wall – Start or finish of the pre-strip bench............................................32
Benchmark – A measure of performance and productivity of a dragline,
operator or process.....................................................................................................33
BER – Bucket Efficiency Ratio ......................................................................................35
Berm – A mound of material placed near the edge of an excavation. ......................37
BEST Practice – The average output of the top 10% of equipment in the PwC
Mining Intelligence and Benchmarking Database ................................................ 38
Blast patterns – Designed to provide the correct broken rock size or break up
coal .............................................................................................................................. 40
Big Muskie – The largest dragline ever built ............................................................... 41
Blackjack – Heavy lubricant ..........................................................................................43
Blast – The area that is loaded with explosives and fired. .........................................44
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Blast Profile – The shape of the overburden after a blast. (May also be called
muck pile profile). ......................................................................................................45
Blasting – Controlled detonating of explosives to break rock ...................................46
Block – The ground removed as one cycle in the dragline sequence as it moves
down the strip ............................................................................................................. 51
Boat (Parts Boat) – Sled for Carrying Spare Rigging Parts, Teeth and Adaptors
and Various Other Items ...........................................................................................52
Boom – The Structure that Protrudes from the Front of the House ........................53
Boom Angle – Angle of the boom from horizontal .....................................................55
Boom Foot (or Boom Root) – The lower end of the boom that attaches to the
revolving frame ...........................................................................................................56
Boom Point Sheaves – The pulleys that guide the hoist ropes over the end of the
boom. ...........................................................................................................................57
Boom Stress – The load put on the boom during operation......................................58
Boom Suspension Ropes – The wire ropes that hold and support the boom and
load.............................................................................................................................. 60
Box Cut – The initial excavation that is dug when opening up a new pit ................ 61
Brake Air Isolators – Isolate air to brakes ...................................................................62
Bridge – Where the dragline builds a pad/bench over a previous pit void .............63
Bucket – The tool the dragline uses to remove waste material .................................64
Bucket Capacity – The volume of the bucket used to define the size. ......................72
Bucket Purchasing – Process for getting the optimal bucket. ...................................73
Bucket – CQMSRazer .....................................................................................................77
Bucket – ESCO ................................................................................................................78
Bucket – VR Steel / VR Mining.....................................................................................79
Bucket Arch – Part of the Front Ring of a Conventional Style Bucket .................... 80
Bucket Factor – Volumetric measure of payload........................................................81
Bucket Filling – How spoil moves into the bucket .................................................... 82
Bucket Lag – The bucket trailing the boom.................................................................92
Bucket Weight – Total in-service weight of bucket. ...................................................93
Bucyrus Erie (Bucyrus International) – BE (now Caterpillar) ..................................94
Bulldozing (bucket) – Bucket pushing spoil in front of itself ....................................96
Bund (normally called Berm) – A mound of material placed near the edges of
an excavation...............................................................................................................97
Buttress – Support or reinforcing................................................................................ 98
Cable (Trailing Cable) – Power Lead that Delivers Power to the Dragline..............99
Cable Access – Roadway for cable ............................................................................. 100
Cable Boat – A structure with an arch that raises the (trailing) cable.................... 101
Cable Covers – Pipes that cover the cable..................................................................102
Cable Handling – Moving the cable either manually or by machinery ..................103
Cable Loops – Storing excess cable ............................................................................104
Cable Pipes – Enable cable access under roadways..................................................105
Cable Plug Sled – Device for transporting cable and plug .......................................106
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Cable Coupler/Cable Plug Stands – Keeps cable couplers/plugs off the ground..107
Cable Towers – Supporting cable above Roadways..................................................108
Cable Winch – At the rear of the dragline for lifting and carrying the cable while
walking.......................................................................................................................109
Cable Winch Rail – At the rear of the dragline for lifting and carrying the cable
while walking ............................................................................................................ 110
Cam – The mechanical device that facilitates the walking action............................111
Carry Angle – The angle between the floor of the bucket and the horizontal ....... 112
Carrying Spoil Down the Pit – When the spoil won’t fit in the available room..... 114
Cast (or Throw) Blast – A blast that throws overburden into the mined out strip 115
Cast Bucket (Castings).................................................................................................. 116
Cast Dump – Dumping the bucket outside the normal dump radius .....................117
Casting the Bucket – When the bucket is “thrown” beyond its normal engage
limit ............................................................................................................................ 118
Centre Pintle (King Pin) – A Shaft Protruding from the Centre of the Tub. .........120
Chasing Edge of Coal – Digging to follow the coal edge from the previous strip . 121
Chop – When the dragline digs vertically down a face.............................................122
Chords – The main frame of the boom ......................................................................123
CIMA – Construction Industry Manufacturers Association....................................124
Coal – A fossil fuel consisting of carbonised vegetable matter. ..............................125
Coal Edge – The edge of the exposed coal on the low wall side ..............................126
Coal Exposure – The amount of coal uncovered by the dragline............................ 127
Coal Mining – Digging, loading and transporting the coal......................................128
Codes – Dig, 0perational, mechanical and delay codes ...........................................129
Continuous Improvement – Always striving for better results ...............................130
Contour Bank – A raised pile along the contour lines of the land. ......................... 131
Conventional Bucket – The design and shape of a bucket that closely matches
the long term norm ..................................................................................................132
Cotton Reel – A mechanical device associated with the miracle hitch...................133
Coupling – Device to join a motor shaft to a gearbox input pinion ........................134
CQMS Razer® – Central Queensland Mining Supplies & Razer Industries .......... 135
Crest – The Top of a Batter..........................................................................................136
Crib – Generic name in the mining industry for a meal during working time ...... 137
Crib Room (Ante Room) – The room adjacent the operators cab ..........................138
Cycle – A dragline cycle is made up of fill, swing, dump and return times ...........139
Cyclical Damage – Stress or damage to the machine due to the normal action of
the dragline ...............................................................................................................146
D Shackle – A part used to join a chain to the socket or bucket ............................. 147
Data and Analytics – The use of data and analytics is a key differentiator for
best practice operations........................................................................................... 147
Delay (Non-Operating Event) – An event causing the dragline to stop.................156
Dig Face – The slope in front of the dragline where the bucket is pulled into. .....159
Dig Plan – How the pit will be dug with the dragline...............................................160
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Dig Rate – The amount of material moved in a fixed time ......................................165
Dig Time – The amount of time spent working productively (hours or
percentage of calendar time)...................................................................................166
Dig Zone – The area the dragline is digging .............................................................. 167
Diggability – How easy the bucket finds the material to load .................................168
Dilution – How much rock is mixed with the coal....................................................169
Dip – Slope of the Coal.................................................................................................170
Direct Cast – Material placed directly on final spoil location ..................................171
Disengage – When the bucket is lifted out of the overburden ................................ 172
Downtime (Delay) – The time the dragline is not productive ................................. 173
Dozer – A tracked or rubber tyred machine with a blade to push material........... 174
Dozer Assist – Work the Dozer Performs that Assists the Productivity of the
Dragline ..................................................................................................................... 175
Drag Brakes – Holding mechanism on the drag system .......................................... 176
Drag Chain – Chains attached to drag ropes ............................................................. 177
Drag Cluster – Joins drag chains, sockets and dump chains ..................................178
Drag Control Lever – Operator’s control of drag function ...................................... 179
Drag Drum – Drum for reeling the drag ropes .........................................................180
Drag Gearbox – Drive speed reduction for the drag drum ...................................... 181
Drag Hitch – Where the Drag Chains Attach to the Bucket ....................................182
Drag Limits – An electronic cut-off to stop the bucket being pulled into the
fairlead sheaves.........................................................................................................185
Drag Motor – Drive motors for the drag function ....................................................186
Drag Rope – Ropes used to drag the bucket..............................................................187
Drag Rope Winch – Winch for pulling drag ropes in to attach to drum ................188
Drag Stall – When the load on the drag motors is so great the bucket stops ........189
Dragging – Function of pulling the drag ropes and bucket .....................................190
Dragline Access – Roadway to the dragline for vehicle traffic. ............................... 191
Dragline Monitors – Recording of dragline information.........................................192
Dragline Ramp – Walk road for the dragline to move from one level to another.193
Dragline Whiteboard – Message Board on Dragline................................................194
DragSim – RungePincockMinarco Ltd ......................................................................195
Drift – A Tool for Removing Bucket Teeth ................................................................196
Dump – Emptying the bucket ..................................................................................... 197
Dump Block – The outer casing that holds the dump sheave .................................198
Dump Equaliser – The Bar that Equalises the Dump Chains .................................199
Dump Height – The height from bottom of the tub to the bottom of the teeth
when dumping .........................................................................................................200
Dump Radius (Operating Radius) – The specified dumping distance from the
dragline ......................................................................................................................201
Dump Rope – The steel rope that facilitates the dumping action ......................... 202
Dump Sheave – The dump sheave holds the dump rope........................................ 207
Dump Time – The time it takes to dump the load out of the bucket.....................208
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Dumping on the Fly – Dropping the material out of the bucket while swinging . 209
Dust Control – Reducing dust while digging.............................................................210
Dyna-Vanes – The structure that channels the air into the dragline house .......... 211
Earth Grid – The electrical earthing mat for the dragline substation ....................212
Elevated Bench – A leveled area built higher than the surrounding bench ..........213
Encoder – Encoders send signals to the monitor .....................................................214
End wall – The face at the start and end of the strip ................................................215
Engage – When the bucket is first pulled into the overburden...............................216
Equivalent Annual Production .................................................................................... 217
Esco – Bucket and rigging manufacturer...................................................................218
Excitation – The function that starts the motors......................................................219
Excitation Isolator – The isolation point for the excitation.................................... 220
Extended Bench – The method of building a bridge away from the high wall......221
Extended Keys – A long key cut extending through multiple blocks .................... 222
Extractor Fans – Remove hot air and dust from the house.................................... 223
Fabricated Bucket – A bucket made almost entirely from quenched and
tempered steel.......................................................................................................... 224
Fairlead Buffer – Device to minimise excessive fairlead movement ......................225
Fairleads – The pulleys that guide the drag ropes in and out of the house .......... 226
Fan House – Structure on top of the dragline that holds the pressurising fans ...227
Fatigue – One of the two types of stress on the dragline structure. ...................... 228
Fault – A Fracture Zone in the Overburden ............................................................. 229
FD – Factor Diggability................................................................................................ 230
Fill Distance...................................................................................................................231
Fill Sink – Backfill the area when the dragline has sunk. ....................................... 232
Fill Time – The time taken to fill the bucket ............................................................ 233
Fire Extinguisher – A tool used for controlling fires ............................................... 234
Fire Panel – Electrical panel that monitors and controls fires in the dragline .....235
Flipping the Bucket – Turning the bucket upside down ......................................... 236
FMM – Factor Make and Model....................................................................................237
Fragmentation – How Well the Overburden is Blasted .......................................... 238
Front Ring – The front structure of the bucket........................................................ 239
FSA – Factor Swing Angle ............................................................................................ 240
G.E.T – Ground Engaging Tools .................................................................................241
GAL – Gross Allowable Load (same as Rated Suspended Load) ........................... 246
Gantry – Attached to the A Frame..............................................................................247
Geology – The structure of the earth......................................................................... 248
Gravel – Surface Material for Roadways................................................................... 249
Guide Post – Delineates Roadways ........................................................................... 250
Haul Road – Roadway for Large Trucks ....................................................................251
Hazard – Something which may result in injury or harm .......................................252
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Heat Map – Identifying high potential areas for productivity improvement........253
High Wall – Wall left in undug overburden ..............................................................255
High Wall Failure – Unstable wall or parts of it ...................................................... 256
High Wall Key (Key Cut) – Trench dug exposing the high wall ..............................257
High Wall Trim – Approximately a bucket width left on the high wall. ............... 258
Historical Data – Information from previous strips ............................................... 259
Hoist Brakes – Holding mechanism on the hoist function..................................... 260
Hoist Chains – Upper and lower hoist chains ...........................................................261
Hoist Control Lever – Control for lifting and lowering the bucket........................ 262
Hoist Dependent – When the operator has to slow swing for the bucket to reach
dump height ............................................................................................................. 263
Hoist Distance .............................................................................................................. 264
Hoist Drum – The drum that the hoist ropes are wound on .................................. 265
Hoist Gearbox – The drive speed reduction between the motors and drum........ 266
Hoist Limits – The electronic cut-off to stop the bucket being pulled into the
boom point sheaves ..................................................................................................267
Hoist Motors – Drive the hoist system...................................................................... 268
Hoist Rope – Used to lift the bucket. ........................................................................ 269
Hoist Rope Guide Rollers – Guide hoist ropes on exiting the machine house..... 270
Hoist Rope Winch – Used when replacing hoist ropes............................................ 271
Hoist Trunnion – Where the lower hoist chains attach to the bucket....................272
Hoisting – The term used when raising the bucket ..................................................273
Hose Reels – A device that houses an air hose..........................................................274
Housekeeping – Keeping a work area neat and tidy ................................................275
IBS Ropes – Intermediate Boom Suspension Ropes................................................276
Idle Time – A stoppage when the operator fails to enter a delay into the
monitor ......................................................................................................................277
In Situ Density/SG....................................................................................................... 278
In-House Phone System – A communication system within a dragline ................279
Inline Air Filter – A filter fitted into an air line .......................................................280
Innovation – Developing New Ideas ..........................................................................281
Inside Bend - A non-straight strip ............................................................................. 282
Inside Key – A trench that the dragline digs while sitting on the outer edge of
the bench .................................................................................................................. 283
Insulator – Power barrier ........................................................................................... 284
Intermediate Sheaves – The sheaves part way up the boom that carry the hoist
ropes.......................................................................................................................... 285
Isolation Lockout – A system to positively remove power from the functions .... 286
Jarring the Ropes – Shock loads passed through the ropes ................................... 287
Jewellery - Another name for the rigging ................................................................. 288
Key Cut – The initial trench dug into the overburden............................................. 289
King Post (King Pin) – A shaft protruding from the centre of the tub .................. 290
KPI – Key Performance Indicators .............................................................................291
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Lacings – The structures that join the chords .......................................................... 292
Lag – The time / distance the bucket is behind the dragline when swinging....... 293
Lay – The rope grooves in the hoist and drag drums .............................................. 294
Leadership – The people at the top and the way they act ....................................... 295
Legra – A high wall pit de-watering pump ............................................................... 298
Leica –Dragline monitor ............................................................................................. 299
Lever Jockeying – Excess movement of the control levers.....................................300
Lighting Control Panel – Switch Board for the Dragline Lights .............................301
Lighting Plant – Mobile pit lighting .......................................................................... 302
Lip – The cast section of the bucket nose ................................................................. 303
Low Wall – Spoil side wall of the excavation............................................................ 304
Low Wall Bench – The area between the low wall crest and the toe of spoil........ 305
Low Wall Block – The low wall side of the dig area................................................. 306
Low Wall Key – A trench dug into the overburden near the low wall batter........ 307
Low Wall Ramp – An access ramp on the low wall side of the Pit......................... 308
Lox Line – The line where the coal is considered of sufficient quality to mine
profitably .................................................................................................................. 309
Lube Drums/Tanks – Bulk storage of lubrication medium.....................................310
Lube Injectors – The lube metering applicators ....................................................... 311
Lube Panel – The lube panel controls the lubrication application .........................312
Lube Pump – High Pressure Lube Pumps.................................................................313
Lube Room – The room that houses the lube pumps / tanks .................................314
Lube System Distribution Board – Distributes oil ................................................... 315
Machinery House (Dragline House) – The House Contains all the Working
Machinery..................................................................................................................316
Main Chords – The main chassis of the boom .......................................................... 317
Maintenance – Managing delays ................................................................................318
Maintenance Logger – A Machine that Measures the Stresses Associated with
the Machine Operation ........................................................................................... 324
MAL (GAL) – Maximum Allowable Load ..................................................................325
Marion – A Dragline Manufacturer........................................................................... 326
Mast – The Mast is Situated between the Boom and A – Frame ........................... 326
Mast Foot – The lower end of the mast that attaches to the revolving frame ...... 328
Mechanical Delay – A stoppage associated with a breakdown or repair of the
dragline ..................................................................................................................... 329
MG Sets – Motor Generator sets................................................................................ 330
Mine Official – A person on a mine site with legal / statutory responsibilities ....331
Mine Planning – An engineering function................................................................ 332
Mine Water – Water collected on a mine site .......................................................... 338
Minescape – Dragline Module (Ventyx) ................................................................... 339
Miracle Hitch – The connection between the dump block and hoist rigging ....... 340
Misfire – The explosive in a blast hole that has failed to detonate .........................341
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Mobile Crib Hut – Portable building for eating meals ............................................ 342
MRC – Maximal Rated Capacity................................................................................ 343
Mud Map – A roughly drawn plan of action............................................................. 344
Multiple Pass – Draglines dig more than one horizon in a strip.............................345
Nodding – When the bucket is disengaged a significant distance from the drag
fairleads the front of the bucket dips .................................................................... 346
Nose – The part of the bucket lip where the adaptors attach to the bucket ..........347
OCE – Open Cut Examiner......................................................................................... 348
Offline Extended Key – A long key cut excavated at an angle to the high wall. ... 349
Offline Key – A key cut dug where the dragline is not parallel nor perpendicular
to the highwall.......................................................................................................... 350
Oiler – Less experienced dragline operator............................................................... 351
Operating Cost...............................................................................................................352
Operating Delay (Process Delay) – A dragline stoppage associated with the
operational side of the dragline process ................................................................353
Operating Time – The time the dragline is available to operate .............................355
Operator – Person who operates the machine or equipment..................................356
Operators Cab – The operator’s control room ..........................................................365
Opportunity Cost ......................................................................................................... 366
Optimum Bucket Capacity (Formula) ........................................................................367
Over Swinging – Swinging past the dump zone....................................................... 368
Overburden – All material removed above the coal seam. ..................................... 369
Over-Drag –The operator continues to drag the bucket after it is full .................. 370
Overhand Chop – When the dragline is digging a block of spoil against a batter
with bucket pulling down under its own weight ................................................... 371
Overhand Dig – When the dragline is digging an open face above the tub level ..372
Overhand Reverse Digging – Non- preferred method of digging ...........................373
Overhead Cranes – Cranes mounted inside the machinery house .........................374
Overload.........................................................................................................................375
Oxidised Coal – Coal that has been Exposed to Weathering...................................376
P & H – Pawling and Harnischfeger...........................................................................377
Pad – What the dragline sits on ..................................................................................378
Page – Early Manufacturer of Draglines, Shovels and Cranes ................................379
Parting – The waste material between two seams of coal....................................... 380
Parts Boat – Sled for carrying spare rigging parts ....................................................381
Payload – The material the bucket carries and dumps on the spoil...................... 382
Payload Optimisation – Increasing the amount of material to the dragline
loading limitation. ................................................................................................... 383
Payout – Moving the bucket away from the dragline...............................................387
Pegasys – Dragline Monitor (Mineware) .................................................................. 388
Pegging – Marking an area ......................................................................................... 389
Pendulum Effect –When the boom stops swinging and the bucket continues the
motion....................................................................................................................... 390
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Pins – A component for joining rigging .....................................................................391
Pit Pump – A dewatering pump used in the mine ................................................... 392
Pit Ramp – Roadway to access the pit....................................................................... 393
Plugging – When the swing motors are reversed to slow or stop the swing
motion....................................................................................................................... 394
Pony Motor Drive – A drive system to turn a motor slowly ....................................395
Positioning / Maneuvering – Walking the dragline to a predetermined location 396
Post Strip – The material left above the coal seam that is not able to be reached
by the dragline ......................................................................................................... 398
Power Control Panel – Cabinet for controlling the power application on the
dragline ..................................................................................................................... 399
Power Switching – Electrical term for turning power on or off .............................400
Power switching is usually a term associated with High Voltage switching.........400
Presplit High Wall – When the high wall is closely drilled and then blasted to
create a fracture line.................................................................................................401
Pre-strip – Lowering the working level of the dragline........................................... 402
Prime – Spoil in the original bank before blasting .................................................. 403
Process Delays (Operating Delays) – Wait on Dozer/Stand Prep (Bench/Pad
Prep).......................................................................................................................... 404
Process Delays – Walking/Maneuvering .................................................................. 406
Production Monitor – A computerised machine that gathers the dragline
performance statistics .............................................................................................408
Productivity – The amount of overburden moved in a unit of time ...................... 409
Productivity (Make and Model Variance) – Difference in performance amongst
different makes and models ....................................................................................410
Productivity Model (Value Driver Tree) – Breaking down dragline performance
into its individual components ...............................................................................412
Productivity Trends – The change in performance over time .................................414
Propel – Walking the Dragline....................................................................................416
Propel Brakes – Holding mechanism on the propel function ................................. 417
Propel Gearbox – The Drive between the Motors and Cam ....................................418
Propel Motor (Same as Drag Motors) – The motors that drive the propel
function......................................................................................................................419
Propel Switch – The Switch that changes Functions............................................... 420
Pulling the Limits – Starting the Block ......................................................................421
Pullback - Sitting the dragline on a pad prepared in the spoil to pull (rehandle)
material higher and further back........................................................................... 422
PURSL – Productive Use of RSL................................................................................ 423
Push Roll – Using the dozer to push the material pulled up with the bucket ...... 424
Ramp – Access to a working area below or above another level.............................425
Rated Bucket Capacity................................................................................................. 426
Reclamation – Re-establishing the waste spoil heaps to a stable and productive
landform ....................................................................................................................427
Reeving – The action of winding the Ropes around the drum............................... 428
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Registered (Mine) Manager – The person whose role it is to meet statutory
(legal) requirements ................................................................................................ 429
Rehandle – Overburden that is Moved More than Once ........................................ 430
Reliability – A measure of availability........................................................................431
Repass (Multiple Pass) – Dragging the Bucket in more than once to fill it .......... 434
Re-route (Cable) – Reposition a power cable so it comes to the dragline from a
different location ......................................................................................................435
Reserves – The Total Tonnes of Coal Available to be mined .................................. 436
Return Time – The Time it takes to Swing back to the Pit ......................................437
Revolving Frame – Main Chassis of the Dragline.................................................... 438
RL – Reduced Level..................................................................................................... 444
Rock Drain – A trench to contain falling / rolling rocks......................................... 445
Roll – Mound of Material the Bucket Pulls up while digging a Block ................... 446
Roll a Bridge – Moving a bridge to mine the coal beneath it ..................................447
Roller Circle – The Roller Circle carries the Entire Weight of the Dragline......... 448
Rope Trays – Containers in the house that hold material that drops off ropes ... 449
Roster – A Dragline Crew’s Working Arrangement ................................................ 450
RSL – Rated Suspended Load .....................................................................................451
Safety – Efficient mines are generally safe mines.....................................................452
Safety Rill – A Small Berm or Bund .......................................................................... 454
SDE – Specific Dig Energy...........................................................................................455
SDO – Specific Dragline Output ................................................................................ 456
Seniority – First on, First off .......................................................................................461
Service Roads – The Vehicle Access around a Mine................................................ 462
SG – Specific Gravity ................................................................................................... 462
Shale – Fine grained material usually found with Coal Seams. ............................. 463
Shift – A crew working a roster.................................................................................. 464
Shift Briefing – A pre-shift talk with the crew.......................................................... 465
Shoe Guides – A device to keep the shoes in position............................................. 466
Short Dumping – Dumping inside the Normal Dump Radius................................467
Shot ground – Blasted overburden............................................................................ 468
Side Cast – Dumping to the side of the block........................................................... 469
Sidewinder – A branded, mechanical means to attach an adaptor to the nose of
the bucket with a side pin ....................................................................................... 470
Signage – Signs around a mine site ............................................................................ 471
Signage Rack – A place to store unused signs ...........................................................472
Signal Bell – A device to attract the operators attention .........................................473
Signal Control Switch – The switches used to send a signal to the bell in the cab474
Simulator – A device that simulates actual conditions ............................................475
Single Pass – Exposing a Single Seam of Coal...........................................................476
Sink – When the Weight of the Dragline pushes the Tub into Soft Material ........477
Sling – Rope used to pull the Trailing Cable ............................................................ 478
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Sockets – Used to Attach Ropes to the Chains ..........................................................479
SOP (Standard Operating Procedure) – Undertaking a job in a safe and
efficient manner using a prescribed approach.....................................................480
Spoil (Waste) – All material removed from above a coal seam (overburden) or
from between seams (interburden)........................................................................481
Spoil Heaps – The piles of waste Material after the dragline has uncovered the
coal ............................................................................................................................ 482
Spoil Pullback – Move Spoil further away from a Pit.............................................. 483
Spoil Room – The amount of available space to dump waste material................. 484
Spot Time – The time difference between cycle time and the combined parts of
the cycle .................................................................................................................... 485
Spotting the Bucket – Placing the bucket accurately in the bank .......................... 486
Spreader Bar – Fitted between the Upper and Lower Hoist Chains. .................... 487
Step Length – Length of a Dragline Step .................................................................. 488
Strip Cut – The Subsequent Excavations after the Box Cut. .................................. 489
Stripping – Digging overburden ................................................................................ 490
Stripping Ratio ..............................................................................................................491
Struck Bucket Capacity ............................................................................................... 492
Stub Line – A feeder power line ................................................................................. 493
Substation – A high voltage transformer .................................................................. 494
Survey – Quantified analysis of an area .................................................................... 495
Sweet Spot – The disengage zone where the bucket payload is maximised ......... 496
Swell – The enlargement of the in-situ overburden after blasting .........................497
Swell Factor – The percentage of enlargement of the in-situ overburden after
blasting ..................................................................................................................... 498
Swing Angle – The angle of the arc the boom travels through from disengage to
dump. ........................................................................................................................ 499
Swing before Disengage (Pulling out of the Bank) – The dragline begins to
swing before the bucket is disengaged from the bank. ....................................... 500
Swing Brakes – The holding mechanism for the swing function ............................501
Swing Dependent – Hoist is slowed to wait for swing to deliver bucket to dump
point .......................................................................................................................... 502
Swing Gearbox – The drive between the motors and swing rack .......................... 503
Swing Motors – Deliver the power that drives the swing motion.......................... 504
Swing Pedals – The foot levers that control the swing function ............................ 505
Swing Pinion – The toothed gear that meshes into the rack .................................. 506
Swing Rack – A toothed circle that the swing pinion meshes with to rotate the
dragline ......................................................................................................................507
Swing Shaft – Large drive shaft between the gearbox and pinion......................... 508
Swing Time – The time it takes from the end of fill time to start of return time . 509
Tail Room – Distance between the rear of the house and an obstacle ...................510
Take a Step (Walk Up on the Block) ............................................................................511
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Terrain for draglines (formerly AQUILA™ Dragline System) – Monitor
(Caterpillar)...............................................................................................................512
Throw (or Throw Blast) – Use explosive to move the overburden towards the
previously mined out strip....................................................................................... 513
Tight Lining – Occurs when the bucket is hoisted too close to the boom..............514
Toe – The bottom of a batter or face .......................................................................... 515
Tooth – The cutting tip that is pinned to the adaptor ..............................................516
Top Dead Centre – Parking position for shoes ......................................................... 517
Top Decile – The Best 10% of the draglines in the world.........................................518
Top Rail – Part of the bucket structure ......................................................................519
Topsoil – The Dirt on the Surface that Grows Vegetation ...................................... 520
Total Steel Weight.........................................................................................................521
Tow Hitch – A device designed to pull equipment ...................................................522
Trailing Cable – Power cable that brings power to the dragline .............................523
Trainee – Person learning to operate a machine ......................................................524
Tritronics – A dragline production monitor manufactured by Leica .....................525
Truck and Shovel Operations ..................................................................................... 526
Trunnion – See Hoist Trunnion..................................................................................527
TSL – Total Suspended Load ..................................................................................... 528
Tub – The base a dragline sits and rotates on .......................................................... 529
Tub Cable Entry – Where the cable enters the dragline tub................................... 530
Tub Cable Hooks – Brackets that hold the trailing cable on the tub...................... 531
Tub Hooks – Large hooks that help lift the tub during the walking process.........532
Tub Spin or Slippage – When the tub turns usually during wet weather ..............533
Two Way Radio – A Communication System............................................................534
UDD – Universal Dig and Dump ................................................................................535
Unconventional Bucket – The design of a bucket that is a different shape to the
perceived norm .........................................................................................................536
Under Swinging – Plugging the machine before the bucket is in the right
position ......................................................................................................................537
Undercutting – Digging too close to below the tub ................................................. 538
Underhand Chop – When the dragline is digging a face below the tub line..........539
Underhand Digging – Normal digging below tub level towards the dragline ...... 540
Utilisation – The percentage of the hours in the day when the dragline is
operational. ...............................................................................................................541
Vienna Test System – Measurement of relevant natural abilities ..........................542
Visibility – Restricted visibility from the dragline cab.............................................543
Volume – The Amount of Overburden in a Given Area .......................................... 544
VR Steel – Van Reenen Steel .......................................................................................545
Vulcan – Dragline Module (Maptek)......................................................................... 546
Walk Road – Roadway for the dragline to walk from one working area to
another.......................................................................................................................547
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Walk Time – A delay recorded while moving the dragline from one position to
another...................................................................................................................... 548
Walk Ways – Access for personnel on the dragline ................................................. 549
Walking (Deadheading) – Also called a “Long Walk” ............................................. 550
Walking (Positioning/Maneuvering).......................................................................... 551
Walking Shoes – The pads that support the weight of the dragline while
walking.......................................................................................................................552
Wedge – Locks the ropes into the socket ...................................................................553
Wire rope – Consists of several strands laid together like a helix ..........................554
Witches Hats – Reflective safety cones for demarcation of working areas............555
Working Area – Dragline boom radius area..............................................................556
Wraps – The number of times the ropes go around the drum ................................557
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3dDig 2000 – Dragline planning software
3d-Dig 2000 is a system designed to model mining processes. It is
based on a 3 dimensional digital terrain modeling engine. Unlike
conventional systems, which provide for independent construction of
completed pits and spoil dumps, 3d-Dig allows for the modeling of the
excavation, dumping and spoil transport processes. The 3d-Dig 2000
program is supported by an array of modeling and visualisation
functionality. An animation system allows details of a proposed
completed design to be packaged and transferred to any PC for
communication purposes. In this way, the most complicated mining
processes can be effectively demonstrated to relevant personnel at all
levels.
The 3d-Dig 2000 mining simulation system provides:

Detailed dragline simulation.

Topographic modeling including excavation and dumping
simulation.

Full 3-dimensional visualisation and animation of all mining
processes.

Detailed volumetric and productivity reporting.

Full topographic and visual representation of geology and
mining surfaces.

Accurate visual representation of mining equipment.
3d-Dig 2000’s advanced modeling functionality is supported by a user
friendly graphical interface. All functions and settings can be accessed
by an intuitive system of menus, buttons and dialog boxes. The system
comes with comprehensive manuals, provided in hard copy and digital
format, as well as extensive training and resource material.
3d-Dig 2000 applications include:

Topographic studies & analysis.

Equipment scheduling, both short and long term.

Developing life-of-mine dumping and final landform
strategies.

Pit design optimisation.
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
Researching, developing and validating new mining methods.

Communicating plans to operations and management
personnel.
It is marketed by Earth Technology Pty Ltd.
Information from http://www.3ddig.com/products_3ddig2000.htm
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A Frame – The anchor for the boom and
mast
The A Frame is a critical component and is attached to the main
chassis of the dragline. It is a large structure as it transitions the load
from the loaded bucket as well as the weight of the boom to the main
dragline chassis, the revolving frame. In the case of an 8050 dragline,
the A frame is attached to the rear of the revolving frame, to distribute
the load.
2 legs of the
A-Frame
The A frame connections to the boom and the structure of the dragline
are critical maintenance / inspection points. A failure of any one of
these connections can be catastrophic (as shown on the picture on the
following page where the A frame connection to the dragline structure
failed.
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http://forums.dhsdiecast.com/default.aspx?g=posts&t=117527
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AC – Alternating current
Alternating current is an electric current that reverses direction
periodically, usually many times per second. Electrical energy is
ordinarily generated by a power station and provided to a customer,
whether industrial or domestic, as alternating current. One complete
period, with current flow first in one direction and then in the other, is
called a cycle, and 60 cycles per second (60 hertz) is the customary
frequency of alternation in the United States and in all of North
America. In Australia, Europe and in many other parts of the world, 50
Hz is the standard frequency.
A number of people, particularly in North America, believe that the 60
Hz electricity in North America vs. 50 Hz electricity in Australia causes
Australian draglines to operate slower than in North America. This is
not observed in productivity data.
A DC power source, such as a battery, outputs a constant voltage in a
single direction over time.
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Access Stairs - Stairway for entry
onto dragline
There are a number of access stairs in and around the dragline. The
stairs used most are the access from the ground to the operator’s cabin.
Some are air or electrically operated and some are fixed. All personnel
should take particular care using the stairs as 25% of all lost time
injuries related to the dragline occur getting on and off the dragline. It
is every employees responsibility to learn the mine’s procedures for
getting on and off and follow them at all times.
Access Stairs
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Adaptor – Fitted to the noses on the bucket
The adaptor connects the tooth points to the noses on the bucket. The
adaptor is used to ensure the tooth point is correctly located relative to
the bucket and to allow tooth points to wear out and be replaced
relatively cheaply.
Dragline
Bucket
Adaptors
Tooth
http://arm.com.au/images/
gallery/drag_adapt_11.jpg
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Advance Bench – Bench ahead of the
current dragline strip
An advance bench is pre-stripping done ahead of the current dragline
strip, mostly above the level of the dragline bench. It is either dug
overhand (above tub level) by the dragline or removed by other means,
usually a truck and shovel operation.
It can be more than a full strip ahead of minimum width for dragline
tail clearance.
Advance Bench
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Air Compressor – Air supply for
dragline functions
There are two air compressors supplying compressed air to a large air
tank which is subsequently distributed by pipes to points around the
machine.
Compressed air is supplied into the boom and mast as well as
activating the braking system. There are a number of safety systems on
the dragline using compressed air. Brakes are attached to all drive
motors for the 4 functions; swing, hoist, drag, and propel. If the
compressed air supply fails or falls below a set pressure level the
brakes engage and excitation drops. This causes the dragline to stop.
The pumps on the lube system require compressed air to operate.
Compressed air is also used during maintenance days to power air
tools and to blow dust out of the dragline house, the motors, MG sets
and other electrical installations.
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Air Conditioner Unit – Cool the cabin
The Air conditioner Unit is mounted on the roof of the operator’s cabin
and ducts the air into the cab and crib room at the desired
temperature. This unit is of a heavy duty, industrial quality to give
good service in the harsh conditions encountered during dragline
operations.
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Air Dryers – Extract moisture from the
compressed air
Normal air always has moisture contained in it (humidity). The
process of air compression concentrates the moisture due and raises
the dew point of the compressed air. As the compressed air cools the
moisture is released due to condensation. The Air Dryers remove the
moisture in the compressed air before it enters the receiver tank. If
dryers were not used the water would rust the pipes and tank as well as
getting into the brake and lube systems.
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Air Horns – Signal horns
Air horns are usually mounted on the front and rear of the dragline as
well as one in the house. These horns are used by the operator to
indicate intentions to people working are dragline.
1 short blast = STOP.
2 short blasts = SWING
3 short blasts = WALK
4 short blasts = TALK (on on-board phone or face to face)
1 long blast = EMERGENCY (stop)
There are a number of other ways of communicating around the
dragline.
Air Horn
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Air Hoses – Deliver compressed air
Air hoses are used throughout the dragline to deliver air to the
required area. They are flexible and are attached to the house air
supply by taps and hose- fittings. The hose-fittings used are of a high
quality and specification as the high pressure has caused incidents in
the past.
Air hoses in the machine should be kept neat and tidy, either hung up
on hooks or used in conjunction with a reel.
Note: Air Hose
Fitting
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Air Receiver Tank – Holds the supply of
compressed air
The air receiver tank is a large pressure vessel that holds the supply of
compressed air. This tank is subject to statutory testing periodically.
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Ancillary Equipment – Equipment that is
used to support the dragline operation.
Ancillary equipment is any machine, vehicle or equipment that is
required for the dragline to do its job. The use of reliable and available
ancillary equipment is a key differentiator for best practice operations.
The following are examples of ancillary equipment to aid the dragline
operation;

Dozer/s for pit and pad preparation as well as spoil removal,
role push and coal clean up

Cable handler for moving dragline cable.

Grader for housekeeping

Light vehicles for transport

Excavator/dozer/small dragline for digging key cut,
interburden, poststrip, other.
Dozers are the most common ancillary equipment and the action of
using the dozer effectively is a major contributor to efficient dragline
operation.
The process of optimising dozer push involves six key factors;
1.
Provide a focus and support for operators
2.
Keep push distance to a maximum of 50 metres where possible
3.
Push horizontal wherever possible
4.
Work dozers as a group if possible
5.
Only work under safe (clean, maximum 2:1 angle) highwalls
6.
Keep sufficient blasted spoil inventory
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Tractor Cable
Dozer
Mine Spec
Cable Boat
Cable Reeler
Examples of ancillary equipment
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Prior bench preparation for dragline.
One key use of ancillary equipment is employing the principle of
keeping the bucket away from the highwall. It is effective in increasing
productivity and involves removing spoil by a variety of means
including blasting and/or ancillary equipment.
The use of a small dragline or an excavator can be extremely beneficial
for jobs such as digging keys, digging relatively shallow interburden or
removing poststrip. If these relatively low productivity actions can be
done with something other than the main dragline/s, then dragline
productivity will normally increase. Every multiple dragline mine can
benefit from the use of a dedicated small dragline or high-reach
excavator.
A slightly different way to look at this, but employed very effectively by
a number of operations, is the use of truck and loader fleets (company
owned or contract) to dig key cut material rather than digging prestrip
material.
Optimising ancillary equipment is a mindset. Like so many other best
practice operating characteristics it is about attitude and may require
thinking outside the box to enhance the dragline progress down the
pit.
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Angle of Repose – The degree of slope of
resting overburden.
The angle of repose is the degree of slope of the spoil after it has been
dumped into position. Different spoil types settle at slightly different
angles. Many dragline plans allow for an angle of repose of 37 o but in
practice most angles of repose are between 30 o and 35o. Mine planners
should obtain measurements of angles of repose in different pits at
their site as the wrong angle of repose (measured when the spoil is
freshly dumped) in plans is a major source of higher than planned
rehandle.
It should be appreciated that the angle of repose may vary within a pit
and also depending on how the spoil is dumped.
The following table defines ranges of measured angles of repose.
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Material
Angle Between Horizontal and Slope of Heaped
Pile
Ratio
Degrees
2.8:1 – 1.0:1
20-45
Common earth
Dry…..
Moist…
2.1:1 – 1.0:1
25-45
Wet…..
2.1:1 – 1.7:1
25-30
Round to angular…….
1.7:1 – 0.9:1
30-50
Sand & Clay………….
2.8:1 – 1.4:1
20-35
Dry……
2.8:1 – 1.7:1
20-30
Moist….
1.8:1 – 1.0:1
30-45
Wet…….
2.8:1 – 1.0:1
20-45
Gravel
Sand
Source: modified from
http://www.catrental.net.au/Customer%20Support/Documents/ANGLE%20OF%20RE
POSE%20OF%20VARIOUS%20MATERIALS.pdf
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Anomalous Damage – Damage from an
action outside standard dragline
operation
Anomalous damage is stress or damage to the machine when the
dragline does something that is outside the range of normal
operations. The graph below demonstrates relative damage caused by
some anomalous actions by the dragline. These actions may reduce
fatigue life and/or may increase buckling stresses.
Relative Damage
Boom Foot
3.00
2.50
2.00
1.50
1.00
0.50
0.00
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Anteroom – Room behind the operators
cabin
The anteroom is the room situated behind the operator’s cabin. It is
also called the crib room. It houses the necessary facilities to enable
the crew to have their meals (crib) in comfortable surroundings. Some
mines have whiteboards and desks in this room to leave digging
instructions for the crews.
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Arch – (Bucket)
The arch of a dragline bucket is either a cast or fabricated structure
which provides structural strength to the front ring and a place for the
dump rope/s to connect to. The arch is hollow and can be tubular or
rectangular in section.
Cast arches are provided on Esco, Bradken and CQMSRazer dragline
buckets. Fabricated arches are on VR Mining dragline buckets. There
is much discussion about which is best; strength and reliability of cast
vs weight saving of fabricated.
http://www.vrsteel.co.za/
products/dragline-buckets/
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ASL – Actual Suspended Load
Actual Suspended Load is the total load carried by the dragline boom
excluding the weight of drag and hoist ropes. Traditionally this has
been called Total Suspended Load (TSL) but should be called ASL to
avoid confusion with Target Suspended Load (TSL).
ASL = Payload + Bucket Wt + Rigging Wt
The ASL is what a dragline monitor weighs when calculating payload.
The monitor payload is calculated by taking the inputted bucket and
rigging weights from the measured ASL. Not updating the bucket and
rigging weights (when new bucket or rigging components and installed
and to account for wear) is a major source of error in monitor payload
recording.
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Availability (see also Maintenance) – A
measure of the amount of time the
machine is available to operate (not down
for maintenance)
One of the key aspects of keeping equipment operating productively is
availability. The primary purpose of the maintenance department is to
deliver reliable and productive equipment to the operations
department. All equipment maintenance should be judged on the
ability to meet best practice availability. The following is the standard
equation for availability
operating hours + process delay
Availability = ------------------------------------------------------------------operating hours + process delay + maintenance delay
Assuming mines work the full 8760 hours in a year (most best practice
mines schedule >8700 hours per year) the following are the average
maintenance delay hours per day for best practice and average for
draglines.
Best Practice Maintenance Delay
1.7 Hrs/day
Average Maintenance Delay
3.6 Hrs/day
The value proposition of maintenance is keeping the equipment
running and available to operate. Consequently, the difference
between an individual mine’s maintenance delay and best practice
(average of the best 10% - what is actually achievable) represents the
opportunity to increase operating time.
There are always opportunities to improve performance in both the
production and maintenance departments’ at all mining operations
and the key is that everyone understands the organisation’s objective
and works together to achieve that goal.
There is a large component of focus and attitude built into this aspect
of best practice operations. Best practice operations analyse and report
on their maintenance practices and continually strive to eliminate
actions which are reducing the value-adding outcomes for the
maintenance department.
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Extra effort translates
into extra availability
of equipment. This
figure shows the
relative value in
putting effort into
maintenance practices.
There is however, an
important aspect to
this plot which
demonstrates that just
putting effort into a
system without a
detailed knowledge of
the system and how
close it is working to its
potential may not
produce the desired
output. If a mine is working at T1 with resulting A1, an increase in time
to T2 results in a relatively large increase in availability of equipment
to A2. If however, the mine is working at T3 with resulting availability
A3 (much closer to the ultimate potential of the equipment) a similar
hours input as previous to T4 will only produce a small increase in
availability to A4. This gain may still be worth the increased time and
expense. It does however, demonstrate that every mine should gain a
firm understanding of how well their maintenance function is being
done and how close to potential the equipment is working. This may
be obtained through benchmarking maintenance and reliability
against the industry performance. The top performers can be assumed
to be operating at close to machine potential.
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Backblading – Pushing material with the
back of a full bucket
Backblading is a process using the pendulum effect of the full bucket
hanging under the boom and held close to the drag fairleads. The
paying out of the drag rope causes the bucket to move away from the
dragline. The back of the bucket pushes spoil to level. The hoist is used
to control the height of the bucket. It is not a good practice as stress
and damage to the machine can result. The operator should always
ensure that the correct tool is used for the job, i.e. the dozer.
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Bailing Mud – Digging mud
Bailing mud is a necessity when coal extraction and dragline sequences
are affected by water. Bailing mud with a dragline is done when the
location is inaccessible for pumps; the slurry is too thick; and/or time
is short. The addition of a top covering on the bucket (which can be
added quickly) as shown in the photo below, is a valuable help to
increase the rate at which the mud can be removed.
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Basket – The part of the bucket which
carries the spoil
The basket is the term used for the area of the bucket behind the front
ring that carries the spoil. The basket comprises steel plates welded
into the frame which may be cast (stronger and more reliable) or
fabricated (lighter and allows more material to be carried).
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Batter – The slope of the high-wall or lowwall
The batter is the term given for the angle of a face of material
measured as the angle between the horizontal and the face. The angles
on a high wall (undug material) are normally steeper than on the low
wall (dug material), as high walls, being in virgin ground, are usually of
more competent material. The batter angle may vary from mine to
mine, however it is usually the competency of the overburden that
dictates the batter angles. Many dragline mines use a 2:1 batter
(approx. 63.4 degrees), however highwalls may be between 1:1 (45
degrees) and vertical (90 degrees). Vertical highwalls are not common
practice due to the potential for failure. The batter on low walls is
generally equal to the angle of repose although it is not unusual to
“undercut” the lower part of the batter to 1:1 or even steeper.
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BCM/BCY – Bank Cubic Metre/Bank Cubic
Yard.
The quantity of spoil that occupies 1 cubic metre/cubic yard of space
before being disturbed by a blast.
The quantity of spoil moved by a dragline is usually defined in terms of
BCM (metric – Australia & Africa) or BCY (imperial – US).
BCM or BCY are calculated by taking the weight of spoil moved and
dividing by the in-situ specific gravity (or density).
Sample Metric Calculation (SG = 2.2 t/CuM).
Number of cycles in a day
=
1,000
Average Payload
=
100 tonnes
Total Movement
=
1000 * 100/2.2 = 45,454 BCM
Sample Imperial Calculation (SG = 3,750 lbs/CuYd).
Number of cycles in a day
=
1,000
Average Payload
=
220,000 lbs
Total Movement
=
1000 * 220000/3750
=
58,667 BCY
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Bench – The leveled area where the
dragline sits and operates.
A bench is a flat area created as part of the mining process either in the
highwall or low wall. The dragline bench is leveled ahead of the
dragline for cable and vehicular access. Dragline benches need to be
level for a dragline to sit and work on. Pre-strip benches or the area for
the next strip need to be prepared for overburden drill access and for
lighting plant access while coal mining.
Spoil spillage is cleaned up on low wall benches to allow access for
lighting plants and to monitor the low wall in case of any spoil
movement.
Dragline Bench
Pre-strip Bench
Low-wall Bench
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Bench End Wall – Start or finish of the prestrip bench
The bench end wall denotes the start or finish of a bench.
Bench End Wall
High Wall Crest
Bench
Batter
Bench
Width
End
Wall
High Wall
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Benchmark – A measure of performance
and productivity of a dragline, operator
or process.
Benchmarking the dragline gives a picture of where the machine is
ranked against other machines in the world. Benchmarking operators
gives a mine information on how their operators are performing as
well.
Because of the variability in dragline operations around the world a
dragline benchmark should be kept in the context of what it is doing.
For example, every dragline around the world can be compared based
on the payload and actual suspended load they carry but it may not be
feasible to compare swing times or cycle times.
Production Time
Production
105%
100%
100.0%
0.8%
Productivity
10.7%
95%
6.0%
90%
5.3%
4.9%
2.6%
85%
81.6%
80%
Best
Practice
Allocated Process Machine
Standby Utilisation Availability
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PURSL
PER
Cycle Time 200BFY
2013FY
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BER – Bucket Efficiency Ratio
Bucket Efficiency Ratio is a measure of what weight of spoil a bucket of
a particular capacity will carry. As such it is a measure of the digging
(getting the spoil into the bucket) and shape (holding spoil in the
bucket) efficiency of the bucket. It is found by dividing the average
payload by the rated bucket capacity.
BER
=
Payload/Bucket Rated Capacity
While BER provides a measure of bucket performance irrespective of
size, its most useful function is in the calculation of optimum bucket
capacity in selecting a new bucket. The formula, which is used to
calculate the bucket capacity to meet the target suspended load is;
OC
=
(TSL – RW)
(BER + BUW)
OC
-
Optimum Capacity (m 3 or yd3)
TSL
-
Target Suspended Load (t or lbs)
RW
-
Rigging Weight (t or lbs)
BER
-
Bucket Efficiency Ratio (t/m 3 or lbs/yd3)
BUW
-
Unit Weight of Bucket (t/m 3 or lbs/yd3)
where
A more detailed version of the formula can be used which accounts for
the fact that the BUW is not consistent with changing bucket capacity.
As bucket capacity increases the bucket will go through different
classes of lip. This is demonstrated in the following plot. In the base
formula the bucket weight equals capacity * BUW.
The expanded formula assumes
Bucket weight = BTFW + Bucket Capacity * BUVW
where
BTFW -
Bucket Total Fixed weight (t)
BUVW -
Bucket Unit Variable Weight (t/m3)
The base formula is the same as this where BTFW = 0
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Constant BUW
More Accurate BUW
Changes in Lip Class
Bucket Weight
BUW
BUVW
BTFW
Bucket Capacity
The formula now becomes
OC
=
(TSL – RW - BTFW)
(BER + BUVW)
While being more accurate there are often good reasons for not going
to this level of detail. A bucket supplier will generally design and build
a bucket depending on structural requirements without reference to a
“target” weight and as such the previous base formula is often
sufficiently accurate to provide an indicative target for the mine and
supplier. Existing site performance or modeling can provide the BER,
while the supplier will provide the BUW or BUVW.
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Berm – A mound of material placed near
the edge of an excavation.
A berm or bund should be placed around any excavation. The height
varies. The mining regulations state “the berm should be half the
height of the largest wheeled machine that uses the area”. These
regulations (in Australia) have been further tightened to now require a
mine to “demonstrate” that the berm is sufficient to stop vehicular
traffic moving nearby. It is also used to identify the pit edge during
service days and allow safe access for vehicles.
Berm or Bund
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BEST Practice – The average output of the
top 10% of equipment in the PwC Mining
Intelligence and Benchmarking Database
Best Practice means, for each individual production
or time utilisation KPI, the average for that KPI
calculated from the top 10% of machine years for
loading units in an agreed benchmark population
when ranked by total annual output. That is, the
machine years for loading units in the agreed
benchmark population are ranked by total annual
output, the top 10% of machine years are selected and
separated out and the average of each individual
production KPI and time utilisation KPIs calculated
for the selected machine years only.
Important note: A particular production or time utilisation KPI,
calculated as the average of that KPI recorded by the top 10% of
machine years for loading units in an agreed benchmark population
when ranked by total annual output, may be lower than what is
achieved for the same KPI when considered in isolation. There is no
machine in the PwC database which achieves the best result in each
individual KPI. Further, a number of KPIs in combination are counterproductive. For example, best practice filling times (lower is better)
rarely provide best practice payloads (larger is better).
The PwC database
The PwC mining equipment database has been gathering production
data from trucks, electric rope shovels, front-end loaders, hydraulic
excavators, backhoes, draglines, drills and ancillary equipment since
1992. The database maintains more than 12,000 machine years of
mining equipment data. The following table and pie chart provide a
breakdown of the data in the PwC database.
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Ancillary
(Dozers,
Graders
etc.)
Drills
Mining
Trucks
Front End
Loader
Hydraulic
Excavator
Electric
Rope
Shovel
Dragline
Characteris
tic/Class
Number of
Models
18
32
51
22
87
60
38
Number of
Machines
174
171
432
298
2,596
286
713
Number of
Mines
74
38
70
58
66
41
22
Equivalent
Years of
Data
1,171
496
869
704
6,510
552
1,850
321M
93M
136M
65M
64M
No of
Cycles
Data as at 16 September 2013
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Blast patterns – Designed to provide the
correct broken rock size or break up coal
Square Pattern: The easiest type of drill pattern to layout and
maintain is the square pattern. This pattern is primarily used in
shallow ground where holes are spaced closely together.
Staggered Pattern: A staggered pattern provides better distribution
of the energy provided by the shot, but requires greater care by the
drill operator when laying out the holes.
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Big Muskie – The largest dragline ever
built
The Big Muskie was a Bucyrus Erie machine model BE4250W. It was
the largest dragline ever made. It was the only BE4250W ever
constructed. Construction began in 1966 and it was commissioned in
1969. It was owned by Central Ohio Coal Company at their
Muskingham Mine; located in Cumberland, Ohio (Guernsey County).
It was operated by AEP until 1991 when it was decommissioned. It
was scrapped in 1999.
Photo: One Hundred Booming Years, 1980, Bucyrus Erie Company
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Big Muskie is considered one of the seven engineering wonders of the
world. It was a one-of-a-kind 4250-W Bucyrus-Erie dragline, the
single largest earth mover ever put into operation. This amazing
machine was over 222 feet tall and weighed 13,500 tons. The boom
was 310 feet long. Mobility was achieved through a massive set of
hydraulically driven walking feet. Empty, the 220 cubic yard bucket
could hold a dozen cars.
Over the course of its career from 1969 to 1991, Big Muskie moved over
608,000,000 cubic yards of earth.
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Blackjack – Heavy lubricant
Black Jack is heavy oil used to lubricate slow moving parts. As it is so
thick, it is applied manually to the dump rope, dump sheave and
cluster and a thinner black jack is sprayed onto the hoist and drag
ropes.
Cleaning blackjack off components is a good job for a student or newly
graduated engineer.
Evidence of
black jack
application
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Blast – The area that is loaded with
explosives and fired.
Overburden blasts are common on many mine sites. Explosive
products are put into the drill holes and detonated to fracture the
overburden ready for the dragline to dig. The quantity of explosive or
powder factor used in each hole depends on the hardness of the
overburden being blasted.
It is normal to move the dragline a safe distance from a blast due
possible damage from fly rock. It may be a requirement to turn the
dragline to face away from the blast while it is set off. Blasting is a
potentially dangerous activity so site procedures should always be
followed.
A Typical Overburden
Blast
After a Blast
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Blast Profile – The shape of the overburden
after a blast. (May also be called muck pile
profile).
In some mines the post-blast material is called the muck pile. The
shape of the blast profile is determined by a few factors; angled vs.
vertical drill holes, detonation sequence, amount and type of
explosives used, etc. Most mines will endeavour to move some of the
prime to its final resting space during the blast. This is called cast or
throw and helps coal exposure rates as there is less overburden to
move with the dragline. The amount of cast or throw may be
maximised but in some cases may be controlled due to the digging
technique to be used.
Blast Profile
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Blasting – Controlled detonating of
explosives to break rock
Overburden blasts are common on a mine site. Explosive products are
put into the drill holes and detonated to fracture the overburden. The
quantity of explosive or powder factor used in each hole depends on
the hardness of the overburden being blasted.
Blasting on mines is a conundrum. The cost of drill and blast (D&B) is
budgeted for and appears in the P&L statement and the initial value is
appreciated. That is, if you don’t blast it you may not be able to dig it
and you don’t have a mine! However, the value-adding of good D&B is
not well understood; The real value of good D&B is hidden.

There is no line entry in P&L income for good D&B.

Often the value is some time in the future.

Value often shows up first in the Balance Sheet as extra inventory
(an asset) and many do not understand this.
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
When more commodity is sold or however the value has been
extracted does show up in the profit and loss it is often not
attributed to D&B.
The ultimate aim of D&B is to deliver a well broken pile which
maximises payload and minimises down time. The optimum blast
delivers a spread of particle sizes; not all big (up to 1/3 width of the
bucket) and not all small.
If the material distribution is optimised (i.e. efficient blasting) the
voids in the bucket are reduced (optimised payload); and it is usually
easier to dig with the flow of material in the bucket or tray optimised
(reduced cycling times and damage).
As a further demonstration of the impact of blasting the following
figure shows a plot of dig rate (BCM/hr) vs. Diggability. Diggability is
calculated as payload divided by energy to fill.
This figure demonstrates the fall in productivity as the material gets
harder to dig with productivity dropping to 20% below average when
the diggability dropped to 40% below average. This plot also
demonstrates that there is no value in creating all small particles when
blasting for a dragline. This creates easier digging (higher diggability)
but reduces average payload and average dig rate.
Planning for blasting should account for the loading unit
characteristics, pit geometry, bench parameters, entry and exit
strategies, etc.
Drilling should be considered in obtaining good fragmentation.
Drilling has to be accurate and undertaken as close to blasting as
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feasible. The location of the hole should be as close to the design
specification as possible. This includes the following parameters;

Diameter of the hole

Angle of the hole

Bearing of the hole

Drill depth

Burden and spacing of the blast design

Down the hole timing

Surface timing.
The blast design should focus on the required outcome, geology and
the variations across the blast area. The importance of rock response
time should also be considered as this also has a significant effect on
blast results and fragmentation. The down-the-hole timing and surface
timing are critical. There are a number of initiation sequencing /
optimisation tools available now and these should be used.
In the absence of blasting expertise on site, mines should access this
expertise through the use of blasting consultants.
The outcome of blasting is only determined when the blasted material
has been dug. The measure of the outcome is called diggability.
Monitor measures of diggability have not been sufficiently accurate to
provide useful information to work with. The best measure of
diggability is payload divided by energy to fill and this should be used
across the digging area to prepare a diggability map for input into the
blast model. This may prove a problem for some mines which have
either no monitor or an inaccurate monitor or a monitor which doesn’t
measure energy to fill the bucket.
There are other tools available to measure fragmentation and these
should be considered if the mine is unable to quantify the fill energy
through the monitor. The following figure shows the output from a
fragmentation photo and the interpretation of that. This is useful
information but this data should be linked to digging outcomes where
the photo was taken.
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The following figure shows the link between fragmentation and the
primary required outcome which is optimising payload.
GEOLOGY
Blast Model
Blast Design
Actual Fragmentation
Forecast
Fragmentation
Blast
MINE
FRAGMENTATION
MODEL
Optimised
Bucket / Tray
Bucket / Tray Types
Existing and Other
GAL
Historical
Fragmentation
Steel Wt.
OPTIMUM
PAYLOAD
Mine Planning
Other
The model shows an interactive process of measuring, forecasting, and
planning to obtain an optimal match between the blast outcome and
the tool digging or carrying it. The key aspects are:

Create a blast model from previous blast designs and actual
fragmentation

Use the model to predict and optimise future blasts and

Create a full site fragmentation model to feed into loading plans
so that optimised buckets / dippers can be used.
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Block – The ground removed as one cycle
in the dragline sequence as it moves down
the strip
The strip which the dragline is digging is divided into blocks. The
dragline will follow a set sequence on most blocks. Blocks are
generally 15-25 metres. The depth of overburden to coal and the
dragline reach, will govern the length of the block.
Width of
Block
Block
Length of Block
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Boat (Parts Boat) – Sled for Carrying
Spare Rigging Parts, Teeth and Adaptors
and Various Other Items
Having spare parts close to the dragline reduces the down time during
a break down.
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Boom – The Structure that Protrudes from
the Front of the House
The boom protrudes from the front of the dragline house. There are a
number of parts that make up a boom. Most booms on larger
draglines are triangular or trapezoidal in cross section; however, some
older draglines have twin booms. In this case two steel structures are
attached to either side of the front of the house and join into a single
structure part way up the length.
Main Chords
Four chords on a Cat, Marion and P&H, and three chords on a BE.
These chords are the main chassis of the boom.
Lacings
The web of steel members providing boom support.
Boom Suspension Ropes
These ropes hold up the complete boom structure.
Boom
Boom
Suspension
Suspension
Ropes
Ropes
Intermediate
Intermediate
Sheaves
Sheaves
Intermediate
Intermediate
boom
boom
Suspension
Suspension
Ropes
Ropes (IBS)
(IBS)
Boom
Boom
Point
Point
Sheaves
Sheaves
Mast
Mast
Lacings
Lacings
Main Chord (4)
Main Chord (4)
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Intermediate Boom Suspension Ropes. (IBS)
These ropes support the centre/midway to minimise flexing. On some
booms, there are two sets of IBS Ropes.
Boom Point Sheaves
These sheaves are mounted on the tip of the boom and guide the hoist
ropes round the end.
Intermediate Sheaves
Placed on the boom frame to guide the hoist ropes and to minimise the
hoist ropes hitting the lacings.
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Boom Angle – Angle of the boom
from horizontal
The Boom Angle is set before dragline is first ordered from the
manufacturer. The manufacturer will offer a number of boom length,
angle and RSL combinations for the dragline. To achieve this angle,
the boom suspension ropes are set to a specific length when the boom
is raised. The boom angle can be changed but requires a further set of
ropes made to length, as well as the boom lowered to fit them. The
normal fixed angle of the boom is between 30 and 42 degrees from
horizontal. This is close to the spoil angle of repose so the dragline can
dump at maximum height in relation to the boom length. The steeper
the angle of the boom, the higher the potential RSL and the higher the
potential spoiling height. The lower the angle of the boom the lower
the RSL and deeper the dragline can dig.
Boom Angle
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Boom Foot (or Boom Root) – The lower
end of the boom that attaches to the
revolving frame
The boom footings are an integral part of the boom structure, and are
what attaches the boom to the main chassis, (i.e. the revolving frame).
May also be referred to as the Boom Root.
Boom
Boom
Footing
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Boom Point Sheaves – The pulleys
that guide the hoist ropes over the end of
the boom.
Boom point sheaves guide the hoist ropes over the end of the boom
and are made to swivel and oscillate so they always align with the
direction of the ropes. It is important that the operator is smooth so
that the ropes don’t jump out of the sheave grooves.
Boom Point Sheaves
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Boom Stress – The load put on the boom
during operation
The stresses on the boom are able to be measured with “loggers”. Due
to its geometry the boom at rest is always under compressive stress.
When the boom moves the stress levels change and in many
components the stress will change in a cyclical manner. The following
plot shows the variation of boom stresses during normal block digging.
When the block starts (shallow digging, disengaging near the boom)
the stresses are higher. As the digging gets deeper in the block the
boom stresses reduce.
Different Blocks
As a general rule, stress is minimised when the bucket is in the plane of
the boom and this is due to the support structures and mechanism.
Stress levels rise significantly when the bucket is outside the boom
plane due to torsional (twisting) forces on the boom structure. This
may occur during disengage and acceleration to swing, dumping and
acceleration to return, as well as during normal operation.
Another factor which has a major impact on cyclical stress is the
actions of the operators. Some operators are harder on the boom than
others.
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New Crew
Anomalous damage/stress is when the operator does something that is
out of the normal scope of operation. These actions include, but are
not limited to;
1.
2.
3.
4.
5.
6.
7.
8.
9.
Lower the bucket (pay out the hoist) while dumping
Dumping on the fly
Swing the dragline while the bucket is still engaged in the spoil.
Hit the spoil while swinging
Jar the ropes
Hoist or lift the bucket while dumping
Overhand digging
Bounce the dragline
Multipass.
These would all be defined as undesirable actions and should be
eliminated wherever possible from a dragline operation.
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Boom Suspension Ropes – The wire ropes
that hold and support the boom and load.
Boom Suspension ropes are large wound wire ropes, usually
galvanised for long term protection. Under normal operation, they last
for many hours of operation (years). Most mines have non-destructive
testing programs in place for monitoring the ropes’ condition. Because
there are multiple ropes it is important to have regularly maintained
rope spreaders to prevent the ropes rubbing against each other.
Boom
Suspension
Ropes
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Box Cut – The initial excavation that is dug
when opening up a new pit
The first excavation in a new pit in a coal mine is called a Box Cut, as
there are no open faces. Box cuts incur large volumes of rehandle in a
dragline operation. They tend to have bends in the pit as they follow
the LOX (line of oxidation) line of the coal seam.
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Brake Air Isolators – Isolate air to brakes
Brake Air Isolators positively lock the compressed air access to the
park brakes of the individual functions, swing, drag hoist and propel.
This is a safety function used in conjunction with the electrical
isolation procedures when there are personnel working on the drive
train.
Brake Air
Isolator
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Bridge – Where the dragline builds a
pad/bench over a previous pit void
Bridges are a walking pad for getting a dragline over the void of the
mined pit to the low wall. Extended bridges to the low wall are not
commonly employed at present as there are many and varied ways of
digging a pit. Most operations use some sort of bridging or benching to
position the dragline, whether in the centre of the pit or on the low
wall side
Dragline Building
Bridge
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Bucket – The tool the dragline uses to
remove waste material
There are a variety of buckets available. The bucket should be matched
to the spoil for optimum productivity.
The dragline bucket is a key component in the dragline operation.
Although there are many factors affecting the productivity of a
dragline, the bucket’s effectiveness during filling, dumping and
swinging has, arguably, the largest influence on the overall
productivity of the dragline.
Wright
Earth Eater
Esco
Scoop
P&H
BE HPS
A bucket is made up of different parts. The front ring can be either cast
or fabricated and includes the arch and the nose. The basket has a
skeleton of steel for strength. The top rail gives the bucket increased
strength
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Fabricated
Front Ring
Arch
Top Rail
Nose
Basket
Cast Front
Ring
The following are guidelines for good bucket design:
1.
Bucket as flat as possible
The efficiency of a dragline bucket is dependent on the volume of spoil
which can be stacked outside the bucket; on top and on the front. The
flatter the bucket, the higher the percentage of spoil outside the bucket
compared to the contained capacity of the bucket.
X
2.
CuM
Top of bucket approximates a square (or a circle)
When stacking spoil on a plane, for a given area a square is a more
efficient shape than a rectangle (less spillage from the ‘top volume’)
whilst a circle of the same area will allow 8% more spoil to be stacked
on it than a square of the same area. As a consequence, the top of the
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bucket should be as close to a circle as possible – engineering design
and practical constraints make this impossible leading to aiming for a
square as the preferred shape.
3.
No front to rear taper inside the bucket
The front to rear taper on a dragline bucket has the impact of
“pinching” the spoil as it travels into the bucket. This pinching
generates forces on the side walls components of which are transferred
backwards towards the front of the bucket and give rise to a “boiling”
of counteracting forces as they meet and interact with the incoming
material in the centre of the bucket. This leads to poor transition of
spoil from the “Active Dig Zone” to the “Active Flow Zone”.
‘Boiling’
Looking down on a bucket
‘Pinching’
Fill material
4.
Drag hitch correctly located
The effectiveness of bucket fill depends on the relationship of the
centre of gravity of the bucket to the line of action of the drag which in
turn is dependent upon the location of the drag hitch. If these are
incorrectly positioned then the bucket will tend to lift or dig in
excessively as it is subject to the momentum effect of gravity and the
drag force. See Bucket Filling.
5.
Inside and outside the bucket should be as smooth as
possible
The bucket should be as smooth as possible inside and out. As soon as
oblique faces are presented to the spoil, the internal friction angle
increases and increased effort is required to push the spoil into the
bucket. The addition of ‘wear defence’ measures adds to this friction
resistance – as illustrated in the following photos. Note the following;
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


Bars across the top of the adaptors
Blocks of steel on the inside walls
Blocks of steel on the outside
These physical barriers to material flow impede bucket filling,
increasing loading energy requirements, and reducing bucket fill.
Excessive Wear Defence
6.
Face of the lip shroud runs down the centre line of the
teeth
The action of the teeth when digging into spoil is to create a line of
break or fracture ahead of and between the teeth. This fracture line
runs along the plane following the centre line of the teeth. Digging is
easiest when the spoil can travel into the bucket ‘smoothly’ along this
plane in the spoil.
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Relative Position of the Lip Tooth and Lip Arrangement
The introduction of side-pinning adaptors has hindered this rule. The
side pin usually runs down this centre line meaning that the lip shroud
cannot go on this centreline. In this situation the face of the lip shroud
should be as close to the centreline as possible but below it. This may
require some very specific discussion with bucket suppliers to ensure
this requirement for best practice is met.
7.
All faces presented to the spoil (lip and cheeks) should
have sharp edges
The presentation of any oblique surfaces or edges around castings,
fixings etc. to the spoil hinders penetration and adds resistance to the
digging thereby reducing the efficiency of fill and increasing fill times
and energy required whilst decreasing payload. This includes the
bottom of the drag hitch extension as this area is a cutting edge.
The figure below illustrates what happens when fine materials impact
on oblique/perpendicular faces (a common situation in agricultural
situations). The fine materials impact on the opposing surface creating
a ‘dead’ zone, these particles bond to form a sharp, ‘cutting’ edge.
Direction of Movement
“Dead” Zone created by spoil
at the front of the bucket
Bucket cheek
Spoil movement into and
out of the Bucket
Digging Fine Particles with Flat Cheek
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In blocky material, the large particles cannot bond but build up against
the face in an increasing width causing a zone wider than the original
edge which moves forward at the front of the bucket in a bulldozing
fashion which impacts negatively on the ease of filling of the bucket.
“Dead” zone
created by
spoil at the
front of the
bucket
Direction of
Movement
Bucket cheek
Spoil movement
impeded by
‘boiling’ action
of large blocks
being bulldozed
Digging Blocky Material with Flat Cheek
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Correct Approach
Incorrect Approach with part of
zone between tooth and drag hitch
presenting a flat face
http://www.arm.com.au/images/Ne
w_51_M_Bkt._Jaw_and_Wing_Shr
ouds.jpg
The three key factors which can be controlled by a mine are;
1. Smooth
2. Tooth and Lip Arrangement
3. Sharp Edges on all cutting faces
As an indicator the following table shows the average bucket capacity
used by best practice draglines. If the specific dragline RSL on a site
varies from that noted multiply the specific dragline RSL by the
capacity/RSL ratio.
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Dragline
Best Practice
Dragline RSL
(metric
tonnes)
Best Practice
Dragline
Capacity
(Cubic
Metres)
Best Practice
Dragline
Capacity/RSL
BE 1260W
73.0
21.9
0.300
BE1300W/1350W
81.8
30.9
0.377
BE 1360W
102.3
43.6
0.426
BE 1370W
134.5
48.1
0.358
BE 1570W
159.1
56.9
0.358
BE2570W/2570WS
260.8
89.5
0.343
Marion 8050
132.7
48.1
0.363
Marion 8200
170.5
68.1
0.399
Marion 8750/8200S
215.4
77.1
0.358
P&H 9020
218.2
74.8
0.343
Data accessed from PwC Mining Intelligence and Benchmarking
database 4 October 2013. Current until 31 December 2014.
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Bucket Capacity – The volume of the
bucket used to define the size.
Bucket capacity almost universally refers to the rated capacity. Rated
capacity equals the struck capacity multiplied by 0.9. The struck
capacity is normally calculated using the waterline capacity using a
plane taken perpendicular to the base of the bucket up from the front
of the lip. Sites can estimate capacity of buckets using the CIMA
(Construction Industry Manufacturers Association) formula (average
height * average width * average length * shape factor – where the
shape factor is normally 0.95 for conventionally shaped buckets).
While the CIMA formula provides a useful comparison between
buckets it is rarely used now as suppliers have complex computer
models for calculating struck and rated capacity. The identification of
the front of the lip (without lip shrouds) is a common source of error in
the calculation of bucket capacity. Best practice sites use the CIMA
formula to compare buckets because inconsistencies are often found
between what suppliers say the capacity of a bucket is and what it is
relative to other buckets on site.
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Bucket Purchasing – Process for getting
the optimal bucket.
Acquiring the right bucket and capacity is a process which should be
undertaken for every bucket purchase. The Best Practice process for
acquiring and optimally using a new dragline bucket requires the mine
to take control of the process. It should not be controlled by suppliers.
1.
Determine what you want
–
–
–
–
2.
3.
4.
5.
6.
Seek expressions of interest
Select preferred suppliers
Scale model buckets offered
Select preferred supplier
Refine capacity and design
–
–
–
–
7.
8.
9.
10.
Existing bucket strategy
Target suspended load
Where will bucket be used around the mine
How will bucket be used (e.g. Chop, underhand, etc.)
Optimise use of wear material
Cutting edges on all faces moving through spoil
Face of the lip runs down centre line of tooth
Front ring and hoist trunnion locations
Contract the supplier
Inspect weekly during fabrication
Commission with expert help
Ongoing bucket management
The formula, which should be used to calculate the bucket capacity to
meet the target suspended load is;
OC
=
(TSL – RW - BTFW)
(BER + BUVW)
where
OC
- Optimum Capacity (m3)
TSL
- Target Suspended Load (t)
RW
- Rigging Weight (t)
BTFW - Bucket Total Fixed Weight (t)
BER
- Bucket Efficiency Ratio (t/m3)
BUVW - Unit Weight of Bucket (t/m3)
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This allows for the fact that bucket weights do not rise at a constant
rate and take big jumps when a new class of lip is used.
The BTFW and BUVW are combined in the following formula to give
the bucket weight.
Bucket Weight = BTFW + OC*BUVW
An idealised bucket weight vs. bucket capacity plot is shown.
In optimising the bucket purchased, the cost should also be
considered. It is proposed that in requesting quotes for buckets, mines
should request, from suppliers, a range of capacities and weights and
corresponding cost of ownership, guaranteed cost to maintain, and
guaranteed life.
As an example, the following may be a supplier’s response for a 50m 3
bucket to the above request. It is taken from an actual response to
such a request.
Weight (t)
Guaranteed Life
(MBCM)
Ownership Cost
(cents/BCM)
Maintenance
Cost
(cents/BCM)
40.0
30
2.0
1.4
37.5
27
2.2
1.4
35.0
22
2.7
1.4
32.5
15
4.0
1.4
30.0
6
10.0
1.4
In this case the mine had previously determined the BER to be 2.00
t/m3 and the target suspended load to be 160 tonnes. The rigging
weight was 22 tonnes. In addition the mine has determined the value
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of dragline productivity to be the incremental cost of moving the prime
by a contractor over the dragline marginal cost and is assumed to be
$3.00/BCM for this example.
In response to this supplier response, the mine calculated the
Incremental Profit in moving 30MBCM for each of the five weight
options. The weights provided feed into the determination of BTFW
and BUVW.
Optimum Capacity
(m 3)
Payload (t)
Productivity (%)
Incremental
Profit ($)
49.3
98.6
100.0%
0.0
50.2
100.4
101.8%
1.50
51.1
102.2
103.7%
2.90
52.1
104.2
105.6%
3.90
53.1
106.2
107.7%
2.10
The best way to visualise this is graphically.
Incremental Profit vs Capacity
It should be understood that the successful application of the financial
approach to determining bucket selection based on value is that the
bucket should wear out before it breaks. If a bucket breaks (because it
is too light or improperly designed/manufactured) the financial
assessment is rendered void.
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In this case, the optimum bucket capacity was 52.3 m 3 weighing 33.5t.
The mine required guaranteed life of 13.36MBCM; ownership costs of
4.5c/BCM; and maintenance costs of 1.4c/BCM.
This is a simplified financial analysis. A more detailed discounted cash
flow using a rate of return could be used along with real values for the
mine although the engineer/analyst should be careful not to use too
much detail. The shape of the plot does not change and it is this shape
which is the key in optimising the capacity of the bucket. There is a
bucket unit weight which provides the maximum return to the mine.
To achieve this optimum the following should be part of the bucket
selection process;



Correct determination of BER.
Range of bucket weights and known/guaranteed life
and costs.
Appropriate financial analysis.
The value of making the optimum selection is substantial. In this
example, it is nearly $4,000,000 over the 30MBCM’s, (probably
around 3 years).
The dragline should have a bucket strategy in place which allows the
appropriate buckets to be selected and then utilised in the areas
designated. The dragline’s designated bucket manager has full control
on what buckets are used where and ensures the best bucket is
available at the point in the pit where it is required.
An optimised bucket is not only a capacity to meet TSL; it is also about
getting the best make and model for the conditions in which it is to dig.
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Bucket – CQMSRazer
CQMSRazer is a supplier of a range of conventional and
unconventional dragline buckets, as well as bucket and rigging
accessories. CQMSRazer buckets include Earth Eater (Conventional
and UDD), Scoop, SCUDD, Lodestar and Hurricane.
Scoop
Earth Eater
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Bucket – ESCO
ESCO is a manufacturer of a range of dragline buckets, rigging and
accessories. They have a long history with dragline buckets including
MkIV, MkV (HDL), MkVI (MM) and Production Master. More
recently Esco have sold the NGB (New Generation Bucket) range and
Pro Fill buckets in the US. Esco are continuing to develop new designs.
Old style Esco dragline bucket
ProFill® Dragline bucket
http://www.escocorp.com/EN/products/Pages/profill-draglinebucket.aspx
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Bucket – VR Steel / VR Mining
The VR bucket is sold by VR Mining which is owned by VR Steel from
South Africa. The VR bucket is fabricated which provides some weight
savings. Recently, VR have released the Taper bucket which has the
rear corners tapered in so that the spreader bar is not required.
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Bucket Arch – Part of the Front Ring of a
Conventional Style Bucket
The arch of a dragline bucket is either a cast or fabricated structure
which provides structural strength to the front ring and a place for the
dump rope/s to connect to. The arch is hollow and can be tubular or
rectangular in section.
Cast arches are provided on Esco, Bradken and CQMSRazer dragline
buckets. Fabricated arches are on VR Mining dragline buckets. There
is much discussion about which is best; strength and reliability of cast
vs weight saving of fabricated.
http://www.arm.com.au/
images/blaircoal.JPG
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Bucket Factor – Volumetric measure
of payload.
Before monitors the bucket factor would be set as a percentage (fill
factor) of the rated capacity of the bucket and was multiplied by the
number of cycles to determine total spoil movement. It is an outdated
term with most draglines able to measure payload with monitors.
However, some mines are using the term “bucket factor” as a
volumetric measure of the payload. It equals the payload as a weight
divided by the in situ SG and is expressed in BCM or BCY.
Bucket Factor = Payload/In Situ SG
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Bucket Filling – How spoil moves into
the bucket
Payload has been identified as the most important dragline KPI. How
an operator fills the bucket has a critical impact on what payload an
operator achieves.
This aspect of best practice dragline operations looks at the way a
bucket fills. That in itself will not make for a best practice operation
but the understanding of how a bucket fills leads to clear guidelines for
how an operator should handle the bucket.
The key factors in how the bucket is filled are;
1.
2.
3.
Have the bucket set up properly – geometry, GET and wear
defense
Operator understands what a full bucket is. The first step
in any proficiency training for operators is always teaching the
operators what a full bucket is. PwC observes on most sites that
there are widely varying opinions from the operators as to what
constitutes a full bucket. It is possible that what constitutes a full
bucket may vary from site to site. However, as a general rule, once
spoil flows over the back of the bucket, it is full. The operator has
no control over a poor bucket design.
Operator is coached in how to fill the bucket
–
–
–
Minimising stalling
Pulling up a sloped face
Optimising the trajectory
A bucket which is dragged into a bank in an uncontrolled fashion will
normally stall. To minimise stalling the operator should be coached in
the correct trajectory of fill and the correct application of hoist rope
load to ensure the bucket keeps moving and achieves the optimum
thickness.
The most widely accepted theory of bucket fill is the “shear zone
theory” (Rowlands 1992) which identifies several different flow
regimes as illustrated in the following figure:
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Active
Activedig
dig
zone
zone
(3)(3)
Active flow
Active flow
zone
(5) (5)
zone
Direction
of Drag
Drag
Direction of
Dead
load
Dead
(4)
load (4)
Tooth
Tooth
VirginVirgin
material
(1)material (1)
Initial
laminar
Initial
layer
(2)
laminar
Bucket
Bucket
profile
profile
layer (2)
“Shear Zone Theory” – Flow Regimes





Regime 1 is the virgin material in front of the bucket.
This area remains largely undisturbed until the final
third of the drag during which “Bulldozing” occurs.
Regime 2 is the initial laminar layer that flows into a
bucket during the first third of the drag. After
entering to a certain distance, this layer fails at the
bucket lip and subsequently becomes “dead” for the
remainder of the drag.
Regime 3 is the active dig zone located above the teeth
and bucket lip. This area develops after the failure of
the initial laminar layer. It is in this area that the
highest forces across shear zones are generated,
especially near the teeth. Because of this, it appears
that most of the material/material frictional energy is
consumed in this area. The size and orientation of this
regime is heavily dependent upon the tooth geometry
and bucket attitude.
Regime 4 is the “dead load” which has resulted from
“live” material in Regime 5 ramping up and over the
initial laminar layer. The lower sections of this regime
become “dead” in conjunction with Regime 2, during
the progressive fill.
Regime 5 is the active flow zone, where the majority of
rapid material displacement occurs. It is here that
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material is transferred from the active dig zone over
the dead load in Regime 4.
A bucket’s filling characteristics and resultant fill time is critical to
productivity. The fill characteristics are dependent on the material
being dug, the overall design and how the bucket engages in the bank.
To determine if a bucket is designed for optimum fill, an analysis
should be performed on the bucket’s force distribution at the point of
engage. This should be repeated for every bucket when it is put on the
dragline to determine the “Optimum Line of Action”. If the Optimum
Line of Action (Drag) intercepts the floor directly on the Centre of
Gravity Line (C.G) then the Drag hitch is designed for maximum tooth
penetration force. In practice the optimum line of action (based on
average engage location can be up to half the distance between the
Ground Zero Point and the rearward limit and the bucket will still
show adequate digging characteristics). In practice it has been found
that the quickest fill occurs when the Line of Action intersects the
bottom line about 25% of the distance from the Ground Zero point and
the rearward limit. It is however, very difficult to be this precise in
setting up a dragline and the digging technique to be used. Any
average intersection behind this zone or forward of the Ground Zero
Point will result in noticeably reduced filling characteristics. The aim
is to have the bucket set-up matched to the “Optimum Line of Action”
to ensure optimal filling.
Bucket force distribution
When digging deep spoil the line of action through the drag is steep,
(pink) and the teeth tend to pull out of the ground. When digging
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shallow, the line of drag action is shallow and the back of the bucket
tends to topple over. This is a simple geometric and weight
distribution issue. More care is required when engaging very shallow
or very deep.
Provide the bucket is not so far out that all the payload is tipped out
when disengaging, the bucket should at all times be disengaged as
soon as it is full. Under no circumstances should the operator make
more than one attempt at filling the bucket. If the bucket has a
significantly reduced load (<50%) when the bucket reaches the drag
limits, the bucket should be swung to dump, making an effort to find a
location to dump with minimum swing angle (must be drag payout
dependent).
The drag angle (of the ropes) can be calculated from;
tan-1 digging depth below the fairleads/horizontal distance
from
the fairleads.
The greatest tooth force occurs when the line of action of the drag force
intersects the weight vector along the line of action of the tooth
resistance, that is, at the “ground point zero” directly below the centre
of gravity. Hence, the optimum drag hitch height (as measured from
the bucket floor line) will vary for different drag angles.
As the drag hitch height increases, the intersection of the lines of
action of the drag and tooth forces will move rearward from the
ground point zero. As a result, the centre of ground support will be
forward of the centre of gravity and the teeth will overly engage. The
limit of this is when the intersection passes the final ground contact
point, after which the bucket will flip forward onto its arch.
Conversely, as the drag hitch height decreases, the intersection will
move forward of the ground zero point and the centre of ground
support will be rearward of the C.G. This inhibits the teeth engaging
until the limit is reached. At this point, the teeth will actually be pulled
out of the bank.
The magnitude of the tooth force when the drag hitch is at its optimum
height is:
R
=
W * cot (Drag Angle)
(N.B. cot = 1/tan)
Thus, it is shown that, as the drag angle changes, the tooth force (and
optimum hitch height) also vary. To choose the correct hitch height,
an average for bucket engage position should be determined for a
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digging block. For example, for the BE 1370W, this is approximately
50 – 60 m from the fairleads, with a 15 m digging depth. That is, a
drag angle of about 20-25˚.
The bucket should at all times be disengaged as soon as it is full.
Under no circumstances should the operator make more than one
attempt at filling the bucket. If the bucket has a significantly reduced
load (<50%) when the bucket reaches the drag limits, the bucket
should be swung to dump, making an effort to find a location to dump
with minimum swing angle (must be drag payout dependent).
The optimum fill of a dragline bucket depends on the following:



Design rules,
Operator keeping the bucket moving.
Bucket is full (according to 2 * rated capacity rule)
generally when spoil starts to flow over the back.
The practical result of the filling theory of the dragline bucket is the
plot shown below in the following figure. Fill Distance and time vary
significantly depending on where the bucket is engaged.
It should be noted that any statement that “a bucket fills in two bucket
lengths” made by a supplier or any other person is not sustainable over
a large number of cycles. As a general rule <20% of cycles will fill in 2
bucket lengths. The exact percentage varies depending on the bucket;
but it is never greater than 20%.
Typical Plot of Fill Distance (and Fill Time) vs. Engage Point
The two issues which a mine has a control over which relates to the
filling of a bucket are;
1.
2.
Controlling the location of the centre of gravity
Creating a sloped digging face
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Controlling the Location of the Centre of Gravity
This is something which personnel can do, by requesting information
for each bucket going onto the dragline on the location of the C of G
when the bucket was last taken off the dragline and when it is being
put back on. Personnel should confirm that it hasn’t moved by more
than 250mm in a horizontal direction.
Creating a sloped digging face
Many operators have been taught to dig a block from the surface to the
top of coal taking horizontal slices. The geometry of the bucket
demonstrates that this is not the most efficient way to dig a block. To
achieve a more consistent line of drag action, as demonstrated in the
bucket force distribution figure, the far edge of the block should be
lowered in each lift. There are two reasons why this is desirable from a
payload perspective. Firstly, it promotes gravity assistance to get spoil
into the back of the bucket. The normal mechanism of filling the
bucket only allows for spoil getting to the top of the spoil heap in the
bucket, (about half way to the back of the bucket) and then rolling
under the influence of gravity into the back of the bucket. Because
gravity plays a key role in filling, pulling up a sloped face increases the
gravity-assist. Ideally the bucket should be pulled up at an angle at
least equal to the angle of repose but less than the angle where too
much of the heaped pile on top of the bucket falls out the back. The
sloped face ideally should be between 30° and 45°. Secondly the
average Line of Action is more consistent and can be closer to the
optimal line of action more often. It produces a more consistent
payload in the bucket
This is important as the key part of bucket filling is to get the spoil
from the Active Flow Zone (5) to shear at the top and run down under
gravity into the Dead Zone (4).
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Part of the reason for clearing the limits is to keep the drag ropes out of
the material being dug. When the drag ropes are pulled through the
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ground the life is reduced and a safety issue may arise through the
snapping of the drag rope.
Getting the drag at the right angle is also important. The achievement
of an optimum filling trajectory should be measured and reported back
to the operator via averages and the plot of frequency and payload vs.
trajectory as shown below. The aim with this plot is to match the
peaks.
Bucket specific trajectory analysis.
Optimal dig face trajectory
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Sub-optimal dig face trajectory
A simple method of determining the application of optimal trajectory
of the bucket is to plot the payload vs trajectory (hypotenuse of the line
from engage to disengage points). A second order polynomial line of
best fit will demonstrate the optimum trajectory to optimise payload.
The slope of the line is calculated by taking the differential of the line
of best fit equation and then solving this for y=0 (the point where the
result for payload is maximised. A sample is shown below.
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Payload vs Trajectory
The formula for this line is shown. The differential is;
Y
=
-0.0308 x +1.0566
Payload is maximised when the slope = 0, i.e. when y=0
Solving for y=0,
0.0308x
x
= 1.0566
= 34.3o
Looking at the plot, it is very likely that most operators will average
less than this trajectory and will require support and regular feedback.
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Bucket Lag – The bucket trailing the boom
Inertia is the tendency of a body to resist acceleration; the tendency of
a body at rest to remain at rest. When swing motion is applied, inertia
causes the bucket to stay at rest until the force of the moving boom is
greater than the inertial force encouraging it to stay at rest. The result
of this is the bucket is often behind the swinging boom. When this
occurs it is called lag. Lagging of the bucket increases damage in the
boom therefore ideal operating performance keeps the bucket under
the boom as much of the time as possible.
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Bucket Weight – Total in-service weight
of bucket.
The rule for determining bucket weight is to include everything welded
to the bucket plus ground engaging tools. This includes all wear
defence, adaptors, teeth and shrouds. The distinction between what is
rigging and what is bucket is that if it is welded to the bucket it is part
of the bucket otherwise it is part of the rigging.
Bucket Weight = Weight of bare bucket + wear materials, adaptors,
teeth, shrouds + anything welded to the bucket.
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Bucyrus Erie (Bucyrus International) – BE
(now Caterpillar)
BE was a manufacturer of a large range of draglines, as well as other
equipment. BE was purchased by Caterpillar Inc. in 2011.
BE previously purchased the Marion Power Shovel Company and
Marion draglines are also now manufactured by Caterpillar. Examples
of BE Draglines:
Cat 8000 series (previously
M8050)
M8750)
M8200)
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BE 1370W
BE 1570W
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BE 2570W
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Bulldozing (bucket) – Bucket pushing spoil
in front of itself
Bulldozing is when the bucket pushes the material in front of the teeth
and may be difficult to load. It is caused by an inefficient transfer of
spoil from the active dig zone to the active flow zone. It is a function of
filling energy being absorbed by inefficiencies in the bucket design,
particularly in the front ring and the angle the bucket is being pulled at
(the steeper the trajectory the more gravity assists the transfer of
material from the active dig zone to the active flow zone). Bucket
inefficiencies can include; the bucket tooth angle of attack is too high
or too low, blunt teeth, drag hitch too high, tapers, a rock caught in or
under the teeth, etc.
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Bund (normally called Berm) – A mound of
material placed near the edges of
an excavation
A berm or bund should be placed around any excavation. The height
varies. The mining regulations state “the berm should be half the
height of the largest wheeled machine that uses the area” It is also used
to identify the pit edge during service days and allow safe access for
vehicles.
Berm or Bund
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Buttress – Support or reinforcing
A buttress is something that serves to support, prop, or reinforce. In
dragline operations they can be used when a bridge or bench is
unstable. Material is dumped at the toe to help keep the bridge or
bench stable. When cast blasting, a buttress at the base of the old high
wall is recommended to help prevent coal seam movement.
Buttress supporting low wall.
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Cable (Trailing Cable) – Power Lead that
Delivers Power to the Dragline
The cable is like an extension lead that brings the power from the
substation to the dragline. The new cable comes in lengths of 300
metres or 500 metres and is about 10cm in diameter. It is very robust
as it has to endure the rigors of being moved around the dragline
bench. The core is made up of 3 cables and a continuity wire encased
in heavy rubber.
Internal view of a typical dragline cable
http://www.directindustry.com/prod/prysmian-group/electric-power-supply-cablesmining-tunneling-23809-146852.html
Dragline Cable
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Cable Access – Roadway for cable
Cable access needs to be prepared to allow safe entry of the cable and
cable reeler to the bench. The access is required to be the minimum
width of the cable reeler, smooth and tidy so the machine is stable
while doing the job.
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Cable Boat – A structure with an arch that
raises the (trailing) cable
The cable boat is a necessary piece of ancillary equipment. A well
designed cable boat allows excess cable to be rolled into the tray so
dragging the cable on the ground is minimised. Also an arch is
required to provide access for the dozer and vehicle access to either
side of the trailing cable from the dragline.
Cable Boat
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Cable Covers – Pipes that cover the cable
Cable Covers are used to protect the trailing cable when swinging a
loaded bucket over it.
The covers are usually cut in half from a large diameter, heavy walled
poly pipe. They are placed over the cable in the area that the bucket
will pass over.
Some mines use a whole pipe with the cable inside the pipe and
positioned as required.
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Cable Handling – Moving the cable either
manually or by machinery
The dragline cable is a very robust piece of equipment, built to
withstand the rigors of being moved (often) not on smooth ground.
Most of the cable movement is handled by a tractor mounted cable
handler. There are a few different cable handlers available and all do
what is required. The critical part of handling cable is not to have a
sharp kink in the cable when towing. The minimum cable radius
required when towing is 1 metre.
The cable should never be run over by the tractor or any vehicle as
internal damage to the cable can result. There may be aspects to the
operation that require manual handling of the cable. If / when this is
the case personnel should ensure correct manual handling techniques
are used to minimise back injuries.
Rope or nylon slings are also used to tow cable. They need to be placed
a minimum of 1 metre apart to stop core damage to the cable.
When moving cable plugs, 2 slings should be placed approx. 1 metre
away from the plug each side and if possible carry the plug on the cable
handler.
Typical
Cable
Handling
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Cable Loops – Storing excess cable
Cable loops refer to the way excess cable is looped when it is stored on
the ground.
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Cable Pipes – Enable cable access
under roadways
Cable pipes are used to pass a cable across a haul road. It is used when
“above the road” cable towers are not high enough to safely allow
trucks or other vehicles to pass underneath. These pipes are buried by
an excavator at least a metre below the road surface. They are large
enough in diameter to allow a dragline cable to comfortably pass
through.
Cable
Pipe
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Cable Plug Sled – Device for transporting
cable and plug
A cable and plug sled is used when deadheading the dragline. A well
designed sled allows the crew to hook up and tow an extra cable and
plug and take the excess weight from the cable boat.
Plug Stands
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Cable Coupler/Cable Plug Stands – Keeps
cable couplers/plugs off the ground
Cable Plug Stands are used to keep the cable plugs above the ground.
Although cable plugs are joined in 2 halves with a rubber seal in the
middle to keep moisture out it is a safety requirement that they not be
immersed in water. Consequently, stands are used to raise them.
There is no single design of stand.
Cable
Stand
Cable
Plug
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Cable Towers – Supporting cable
above Roadways
Cable Towers are used for lifting the cable above roadways to allow
vehicles to safely pass under. There are a number of cable tower
designs and it important that they are stable and when attaching the
cable to the lift ropes, no personnel are positioned below the cable
should it fall.
Cable Towers
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Cable Winch – At the rear of the dragline
for lifting and carrying the cable while
walking
Most draglines have an electric or air operated winch mounted on the
rear of the machine to allow the cable to be carried when walking. A
rope sling is always attached to the cable and the winch chain is
attached to the rope. This rope is a safety device and should the cable
be tensioned during the walking process it should break and thus the
cable is not damaged.
When walking the dragline with the cable on the cable winch the
grounds person should be in close proximity to monitor the operation
and make adjustments as necessary. It is noted that some draglines
have a cable winch on the front of the machine as well to assist and
minimise manual handling when putting cable on or off the tub cable
hooks.
A tool that is attached
to the front winch, for
rolling the cable on to
the hub cable hooks
Rear Cable
Winch
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Cable Winch Rail – At the rear of
the dragline for lifting and carrying the
cable while walking
The cable winch rail is positioned at the rear of the house and allows
the winch to be moved in an arc. Not all draglines have a rail and the
winch is fixed. There are pro’s and con’s for winch rails.
Pro’s
The winch can be moved to position above the cable when preparing to
walk. Less cable positioning.
Con’s
An unexpected winch movement along the rail has resulted in injuries.
Winch
Rail
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Cam – The mechanical device that
facilitates the walking action
In walking (dragging) the dragline to a new position the cam rotates
and lowers the shoes to the ground then lifts the rear of the machine
off the ground and drags the machine along the ground. It then lowers
the machine to the ground and lifts the shoe and rotates to the ground
again for another step. Most dragline takes a step of approximately 2
metres and walk at about 100 metres an hour. Draglines always walk
backwards with the boom pointing where it has walked from.
Note Can Action
Cam
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Carry Angle – The angle between the floor
of the bucket and the horizontal
The carry angle is the attitude of the bucket at a set distance from the
dragline in relation to the length of dump rope. The ideal carry angle
for conventional buckets is 35 - 36 degrees.
Carry
Angle
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Carry (or Swing) over the Cable –
Carrying a loaded bucket over the cable
There are times when it is more productive to swing the loaded bucket
over the trailing cable. This is normally to shorten the swing angle.
This should not be done without protection on the cable. The trailing
cable may be covered, usually with a poly pipe cut in half, to protect it
from falling rocks and debris.
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Carrying Spoil Down the Pit – When the
spoil won’t fit in the available room
In certain circumstances it is impossible to fit all the spoil in the room
available. This is most often associated with a ramp but can also
happen where an in-pit bridge is left from the previous strip or an
inside bend or an endwall. When this happens spoil can’t be dumped
on the spoil but should be dumped in a position where it will be
rehandled later in the strip. Identifying these problem areas in a strip
is important before the dragline is working in the strip so that a
workable plan can be determined to fit the spoil in the available room.
An indicator of spoil being carried down the pit is where the peaks of
the spoil pile are all at the dragline hoist limits for an extended length
of the pit.
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Cast (or Throw) Blast – A blast that
throws overburden into the mined out
strip
A cast blast is when explosive is used to move the overburden as far
out into the previously mined pit as possible.
The way the blast pattern is drilled and tied up effects the amount of
overburden prime that is cast into spoil.
Proposed
Low Wall
Virtual shape of a
Cast Blast
Prime Cast
to spoil
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Cast Bucket (Castings)
Casting is a manufacturing process by which a liquid material is
(usually) poured into a mould, which contains a hollow cavity of the
desired shape, and then allowed to solidify. The solid casting is then
ejected or broken out to complete the process. Casting may be used to
form hot liquid metals or various materials that cold set after mixing of
components (such as epoxy, concrete, plaster and clay). Casting is
most often used for making complex shapes that would be otherwise
difficult or uneconomical to make by other methods.
The cast parts of the bucket may include the front ring (arch, lip,
cheeks, etc.), top rail and heel area.
While some buckets are largely fabricated the lip is usually cast due to
the higher strength particularly in the corners.
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Cast Dump – Dumping the bucket outside
the normal dump radius
Cast dumping is when the operator dumps the bucket outside the
specified dump radius. This is normally achieved by dumping the
bucket while still in swing motion. Decelerating the boom while
dumping causes the bucket to follow a circular motion under the boom
point. This action can cause the bucket to hit the boom and has caused
a number of failures of booms within 20 metres of the boom point.
Analysis of boom stress monitor data shows that this practice causes
anomalous stresses to the boom structure, and should
be minimised.
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Casting the Bucket – When the bucket is
“thrown” beyond its normal engage limit
Casting the bucket is a practice that should be minimised during the
dragline operation. It is done by creating a pendulum with the empty
bucket. The bucket is dragged in quickly and then the drag reversed.
The drag rope goes slack and the pendulum effect of the bucket under
boom point causes the bucket to swing out beyond boom point. The
hoist is paid out to engage the teeth when the bucket is beyond boom
point.
If the bucket has to be cast to pick up the toe of the block,
consideration should be given to shortening the block lengths, or
tucking up block toe a little steeper if it is safe to do so.
Casting the bucket puts abnormal stress on the boom and the operator
needs to be made aware of this.
To cast the bucket, drag
in then payout quickly.
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Empty bucket swings
out due to pendulum
effect and engaged at
the point the bucket is
furthest from the
dragline.
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Centre Pintle (King Pin) – A Shaft
Protruding from the Centre of the Tub.
The centre pintle is a shaft attached to the tub, and inserts into the
main chassis of the dragline, the revolving frame, to allow the machine
to rotate and keep it aligned on the roller path and tub. The power
cable to the working machinery in the house come through slip rings
attached to the centre pintle.
The centre pintle is also called the King Pin or Post.
Centre
Pintle
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Chasing Edge of Coal – Digging to follow
the coal edge from the previous strip
There are a number of options for a dragline clearing the low wall side
of the coal. Some mines will clean the edge of the coal on the design
line or a bucket width outside design line. Some mines dig a bucket
width slot through the coal on or outside design line. Some will follow
the edge of coal. Each has its advantages and disadvantages and each
mine needs to determine their own procedures. When a dragline
chases the edge of coal it means that the dragline may incur more
rehandle in moving the spoil further back when the coal seam moves
during blasting. One problem in chasing the edge of coal is that there
is no indication as to whether the full thickness of coal has moved. It is
not uncommon for the top of the seam to shear and the coal only to be
300mm thick at the edge.
Buffering the coal seam will help to hold the seam in place during
blasting operations.
Chasing
Coal Edge
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Chop – When the dragline digs vertically
down a face
The normal action of the bucket is pulling it into and along the bank
towards the house. On some occasions the bucket may be pulled down
a bank, either against the high wall or the low wall. This action of
pulling the bucket down a bank is called chop or chopping. Chopping
can be done above the tub level and below the tub level.
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Chords – The main frame of the boom
The chords are the main frame, or chassis of the boom or mast. The
pipe chords on the lower end of the boom are pressurised as a check
for any cracking in the structure.
Chords
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CIMA – Construction Industry
Manufacturers Association
CIMA is most commonly referenced as the standard formula for
calculating bucket capacity.
Struck Capacity = Total Length * Ave Height * Ave Width * F
Where F is a Form Factor accounting for the rounded back on the
bucket. For conventional buckets F equals 0.95.
Rated Capacity = Struck Capacity * 0.9
The CIMA formula for bucket capacity is not frequently used now as
bucket suppliers use computer models to calculate struck capacity and
apply the 0.9 multiplier to give rated capacity.
Struck Volume
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Coal – A fossil fuel consisting of
carbonised vegetable matter.
A fossil fuel consisting of carbonised vegetable matter deposited in the
Carboniferous period and altered through the actions of heat and
pressure.
The coal seam is compressed vegetable matter laid down in horizontal
layers. Some mines have multiple seams that they mine.
Coal Seams are varied and of different qualities.
Overburden
Coal
Seam
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Coal Edge – The edge of the exposed coal
on the low wall side
The coal edge is the low wall side of the exposed coal seam. Most
operations prefer to dig a bucket width down to the bottom of the coal
seam to allow cleaner extraction of the coal. This procedure comes at a
cost of extra rehandle as the low wall has to be moved further out to
maintain the correct angle and for the toe to meet the trench floor.
Coal
Edge
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Coal Exposure – The amount of coal
uncovered by the dragline.
This is the term for uncovering coal with the dragline. The prime
concern for a dragline operation is to uncover coal in the quickest and
most economical way. The method of uncovering the coal is an
important consideration. Most dragline operations use a dozer to
clean the top of coal in order to minimise coal losses.
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Coal Mining – Digging, loading and
transporting the coal
Coal mining is made up of digging, loading and transporting the coal to
the wash plant. Most times the coal seam is blasted to break up the
hard coal seam to make it easier to dig.
Digging & Loading: There are many machines for digging and loading
the coal. The mines that have large coal seams mostly use Trucks and
Shovel extraction.
The mines with smaller seams use excavator and/or front end loader.
The truck fleets can vary from bottom dumpers to rear dumpers. Some
even use conveyor systems.
Some of the smaller mines use road trains to haul the coal.
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Codes – Dig, 0perational, mechanical and
delay codes
Dragline production monitors are used to collect operational data
which is then used to analyse the productivity of the operator and
machine.
To identify different operations, codes are used. Some of the codes are
dig, operational and mechanical delay codes.
Monitor Screen with some delay codes
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Continuous Improvement – Always
striving for better results
Continuous improvement is the seeking of small improvements in
processes and products, with the objective of increasing
quality/efficiency and reducing waste. In the current difficult
operating environment it is important for everyone to strive for
continuous improvement. With technology advancing quickly mines
need to keep up or get left behind in the area of dragline productivity.
Benchmarking and production monitors provide the information to
know where the productivity of the dragline can be increased, so the
efforts can be concentrated on the areas which can be improved.
Processes such as Lean or Six Sigma put a specific structure to the
process of business or continuous improvement. In reality, continuous
improvement is based on two simple steps. Firstly, measure the gaps
and secondly, do something about eliminating or reducing them.
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Contour Bank – A raised pile along the
contour lines of the land.
Some draglines are involved with rehabilitation. A Contour Bank is
constructed along specific contour levels of the land. These banks on a
mine are built on reclaimed land in order to trap water runoff and
prevent erosion.
Contour
Banks
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Conventional Bucket – The design and
shape of a bucket that closely matches the
long term norm
For many years dragline buckets followed a very similar design. This
style of bucket is now referred to as a conventional bucket. Although
there are many conventional shaped buckets on the market,
refinement of design in the last few years have improved the
productivity of the buckets.
1913
Current
Conventional
Buckets
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Cotton Reel – A mechanical device
associated with the miracle hitch
The cotton reel shaped device allows flexible movement between the
miracle hitch and the dump block.
Cotton
Reel
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Coupling – Device to join a motor shaft to
a gearbox input pinion
A coupling is an internally flexible device that joins the drive motors to
the relevant gearboxes.
Coupling
Hoist
Gearbox
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CQMS Razer® – Central Queensland
Mining Supplies & Razer Industries
CQMS Razer® is an Australian company that manufactures and
supplies bucket and rigging components to the mining industry.
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Crest – The Top of a Batter
Crest is the top of a sloped area of spoil.
High wall and Low wall crests are typical.
High
wall Crest
Low wall Crest
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Crib – Generic name in the mining
industry for a meal during working time
Crib is the generic name given to a meal taken during the working time
in a coal mine. Its origin is believed to have been the coal mines of
Wales in the 18th century where the miners played cribbage during
breaks. This became shortened to “going for Crib”.
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Crib Room (Ante Room) – The room
adjacent the operators cab
The crib room is situated behind the operators cab. It has sufficient
household equipment to maintain a 24/7 operation for the operators.
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Cycle – A dragline cycle is made up of fill,
swing, dump and return times
A cycle is the time frame for the dragline to go from one specific point
in the cycle to the same point in the next cycle. It is often defined as
the start of bucket fill but sometimes is the end of dump. The cycle
time is made up of fill, swing, dump, return and spot times. The total
time of these processes is cycle time. The following plots demonstrate
typical 10Hz data with the five key pieces of information required to
identify the defining points in the cycle.
This data shows four distinct cycles characterised by the rapid rise in
drag force (light blue) when filling and the rapid drop in hoist force
(purple) when dumping.
The following five plots demonstrate and explain each of the five key
pieces of information which can be used to distinguish the cycle
components.
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Swing Position. (Red) Can be seen to be reasonably constant when
the dragline is not swinging. In the dragline data the swing out is seen
as a movement one way and the return is seen as a movement the
other way
No swing – flat
during fill
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Drag Force (Drag amps). Light Blue. Is relatively low as the bucket
is returned to the face after dumping. When bucket engages drag force
rises rapidly and with large gyrations. It may peak and drop off while
still filling due to stalling and/or the variable application of hoist
loading during fill. When bucket stops being dragged in drag load
peaks and will drop quickly. Depending on how disengaging is done it
can become very low for a short period but this is not always seen. As
drag is paid out to dump the load drops until a minimum load is
recorded during/post dump. It then remains low during retrieval and
return.
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Hoist Force (Hoist amps). Purple. Is relatively low as the bucket is
returned to the face after dumping. Load reflects weight of bucket and
chains. When bucket engages hoist force drops as bucket is engaged
and most times hoist will go slack. It may rise during filling as hoist is
used to keep drag moving in and in some cases may rise substantially if
bucket stalls. When bucket disengages the hoist rope load will rise
rapidly to a peak and will settle to a load a little below the peak.
Depending on how swing to dump is done the hoist rope may rise or
fall. Higher trajectories give higher loads. At some point the hoist load
will peak and then will fall to the point where dumping starts at which
point the hoist rope load falls quickly. It then remains low during
retrieval and return. Load reflects weight of bucket and chains.
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Drag position (Drag velocity). Dark blue. Immediately prior to
engaging the drag position changes direction as the drag is initially
paid out to get the teeth to point down and engage and then pulled in
to start the filling. Bucket may stall but won’t change direction unless it
is going to swing or repass (another attempt at filling). After
disengage the direction of the bucket changes. Drag is generally paid
out consistently to dump. Drag payout speed may vary but it rarely is
dragged in during swing. At dump the change in drag position/drag
velocity is fast as the bucket is dumped and then retrieved for
returning. The drag position during return will depend on where the
bucket is to be engaged. A characteristic double change in drag
position occurs as the bucket is preparing for engaging. The size of
this jump depends on how the bucket is engaged and may not be
present at all if the bucket is sat straight down on its floor prior to
filling.
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Hoist position (Hoist velocity). Dark pink. The hoist is used to
control the way the bucket digs. Generally it will pay out a little during
fill depending on the geometry of the dig face. During disengage it will
change direction quite quickly and then will continue to be pulled up
until the dumping height is reached. After dump the hoist will
normally change direction and return to where will engage the next
cycle.
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Cyclical Damage – Stress or damage to the
machine due to the normal action of
the dragline
Cyclical damage is the stress put on the machine under normal
operation. There will always be some stress on a machine in operation,
and it is the responsibility of the operator to operate within best
practice guidelines. The following plot shows the variation of boom
stresses during block digging. When the block starts (shallow digging,
disengaging near the boom) the stresses are higher. As the digging
gets deeper in the block the boom
stresses reduce.
4
3.5
3
2.5
Susp
Boom
Different Blocks
2
1.5
1
0.5
0
10/05/2003 0:00
11/05/2003 0:00
12/05/2003 0:00
13/05/2003 0:00
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14/05/2003 0:00
15/05/2003 0:00
16/05/2003 0:00
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D Shackle – A part used to join a chain to
the socket or bucket
There are a number of D-Shackles in the bucket rigging. These include
one on each end of the 2 drag chains and smaller ones on each end of
the dump chains. They are used as a joining link.
http://www.arm.com.au/images/
Large_Drag_Shackle_A.R.M_Hardfaced.jpg
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Data and Analytics – The use of data and
analytics is a key differentiator for best
practice operations.
The single most important thing a dragline mine can do is to develop a
reporting methodology which focuses on what needs to be done to
improve the dragline operation.
There is no single set of metrics that will be meaningful to every mine
and organisation so you should determine what is meaningful to you.
Engineers and mines should get away from reporting the usual banal
data statistics which they have presented to executive management
and boards of directors for too long. Something meaningful is
something which can be and is acted on and something meaningful is
what is needed.
Good metrics remove opinion from the equation and provide a solid
base for effective decision-making. Whether your focus is on a broad
productivity measure like annual output or a specific KPI like payload,
if you learn how to use analytics you will uncover weaknesses across
the value chain.
The metrics most meaningful to a dragline mine is going to depend on
what the mine’s strategy is. If a mine is focused on maximising output
without regard to anything else then KPI’s around total annual output
for all equipment around the mine is of primary importance.
When margins slide as they are now, the focus will shift to more
specific interest in what rates individual equipment is achieving on a
yearly, monthly, weekly, hourly basis. Focus will return to time
utilisation.
If a mine is running a genuine business improvement process on their
draglines (all mines should be continuously) they will be focused on
KPI’s like payload, number of cycles, cycle time, etc. Each of these
KPI’s have traps and can be manipulated to tell a story so be careful in
how you interpret them or in what is presented to you.
Industry performance standards can be useful for determining what is
good performance and what is not. There are numerous case studies
which demonstrate how companies think they are doing well because
they have improved compared with a number of years ago. This
actually does not prove they are doing well compared to the dragline’s
ultimate capability.
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No discussion about analytics can ignore a comparison with what other
people achieve with the same piece of equipment. Benchmarking
should be at the core of dragline analytics. Many mine engineers and
managers find excuses for poor performance and comparisons with
industry standards are definitely not on their agendas.
“But my operation is different”, is the standard response when talking
about comparing draglines. It is true that every dragline is slightly
different in the work it does and how it does it, but every dragline has
the same basic physical configuration. Every dragline has twenty four
hours per day in which to function. Every dragline has an operator and
needs ancillary equipment to function at its highest level. Some dig
deep and others dig shallow. Some have hard digging and others soft
digging. Some have multiple seams and some have single seams.
Comparing dragline performance between mines (benchmarking) can
be done to advantage by properly normalizing the data for time
utilization, size, and target suspended load. Every legitimate
differentiating factor may then be reviewed and a fair performance
comparison is brought into view. Many mines are shocked by first
time benchmark results and dismiss it with - “But my operation is
different. We can’t do better than we are now.” These mines are
consigned to mediocrity. Best Practice in large measure is a matter of
attitude.
Getting down to where the “rubber meets the road” and the “dragline
engages the dirt”, many frontline supervisors find themselves with too
many issues demanding their time. They need support to be able to
work with their operators to improve their output. Best practice mines
use data to help them prioritise improvement actions. A table such as
the heat map in the later section under this name can be useful to
guide business improvement.
Best practice operations spend more time in a day studying and
actioning information from reports than the average operation may do
in a month. Reports of performance are a key learning and action tool
for all personnel associated with the equipment and time should be
committed every day to analysing reports; actioning change for loss
events; learning how to replicate good performance; and reconciling
the process and the outcomes.
Data is the most valuable strategic resource for the mine site and its
use should be planned and optimised to add value to the operation.
The data should be treated as being important and only competent
people should have access to the data to do analysis. The mine should
establish a register of competent people and companies who can
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provide them with objective and professional analysis and then use the
data for reporting, forensic analysis, forecasting, prediction, etc.
There is a very large number of ways of demonstrating outcomes as
interpreted from data. Some are more useful than others but the
overriding considerations are;
a.
The report/s should be meaningful
b. The reports should be used
c.
The reports should support decision-making
d. People should be trained and supported in interpreting the
analytics used in reports.
There is a very large range of analytics which can be applied to the
data. The following is a list of the analytics which can be done. The
subsets under each area are only limited by what is meaningful to the
mine.
1.
Standard reports
Daily, Weekly, monthly, annual, benchmarking, crew, individual,
buckets/dippers, blasting, reconciliation, etc.
2. One-off reports / data drill down / forensic analysis
Failure analysis, change analysis,
3. Real time data & alerts
Stress overloads, over speed, digging above/below planned R.L.
4. Statistical Analysis & Data Mining
Prioritised list of loss events, reliability analysis, etc.
5. Forecasting & Predictive Modelling
Blast models vs. location in pit, Bucket/dipper strategy, etc.
6. Optimisation
Bench heights/widths vs. digging strategy,
Best practice operations undertake regular benchmarking of
performance against previous periods and against similar populations
outside their operation. This approach provides an “inside” and an
“outside” view of their performance. They recognise that there are
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learning’s to be had from other operations and they look to access this
information through a benchmark.
An important aspect of data use is a time model used consistently by
all personnel to record and report equipment performance. A sample
time model is shown in the following figure.
A number of examples of data presentation follow in the figures shown
over.
Each site may have different reports but the imperatives are that the
reports are meaningful and able to be acted on and they should be
discussed one-on-one.
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Review of Operator individual performance sample.
Example of two KPI’s with third dimension – size of bubble.
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Review of Operator individual performance sample.
The use of data is a clear differentiator of best practice mines. The
following points should be noted.

While data use has become more common, most mines and
mining companies still rely on traditional technology and are not
using data and analytics to support decision making to a high
degree. Spreadsheets are the number one tool used in analytics.

Intuition based on experience is still the driving factor in most
decision making. Many decision makers simply do not believe
that mining data can be used effectively.

Non-mining companies are looking to data and analytics to solve
big issues; reducing costs, improving profit and managing risk.

Data is the number one challenge in mines embracing advanced
decision making. Mines are struggling with accuracy, consistency,
access and the skill levels of people charged with using the data.

Many mines do not have a culture which supports the use of data
and analytics.
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
In mining, real business improvement does not need Six Sigma
nor Lean nor any one of a range of proprietary methods. These
methods simply put a process or a structure in place to guide
actions. Unfortunately, they often fail to add value because the
practitioners are trained in and only execute a process. Reward
and recognition are given for conforming to process; not the
outcome achieved. In its simplest form Business improvement has
only two stages when comparing “what is” to “what is possible”.
1.
Measure the gaps in performance (data and analytics).
2.
Do something about them (action).

Measuring the gaps in performance to support effective decision
making requires an analytic approach to the available data.

When some mines begin using their data they frequently have
insufficient analysis and occasionally the “wrong” information
reported. The challenge for them is to apply analytics (including
advanced analytics) to information from both inside and outside
the mine to detect complex patterns (signatures) and trends that
will help find the gaps and the potential available through change
(optimisation).

Best practice mines are very good on the “action” part of the
process. This is a challenge for many mines and mining
companies. The ability to implement change is the greatest ability
of an organisation. This is tied up in personalities, culture, and
leadership. The move to an analytically focused company will
require increasing confidence that closing the identified gaps does
improve performance.

A best practice mine will not wait for the data to be perfect (this is
often used as an excuse for inaction); it is more important that
some small improvements are achieved on which the mine and
company can build. Successful business improvement using
advanced analytics employs the following key factors to close
performance gaps.
o
Select projects with a strategic alignment. For example, more
tonnes, lower cost, etc.
o
Benefits should be measurable.
o
Management support is essential, General Manager, Executive
Management, etc.
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o
Have the necessary expertise to thoroughly understand the
processes involved.
o
Specifically define the factor limiting performance in a way
that action can be taken. Truly understand the problem.

The imperative to facilitate change in today’s mining business
improvement scenario is that what has been done during the 8-10
years of boom times will almost certainly not work through a
period of declining profitability. To avoid inaction it should be
understood that its roots are often in over-analysing once an issue
is known or understood. This approach is used by decisionmakers without confidence to make the indicated decisions.
Secondly, inaction can come from waiting for quality data or data
which doesn’t exist. The data is “never good enough” to act on
which again demonstrates a fear of acting. Finally, mines and
mining companies are much more likely to penalize failed action
rather than inaction. The person to be promoted is the person
who hasn’t “stuffed up”.

Finally, an empirical approach should not discount the value of
experience and intuition. Data can be interpreted in many ways
and the formation of a theory (gap identification) should be
backed by an assessment by the analyst as to whether there is
enough data and the right kind of data to form the theory.
Experience and intuition play an essential role and should never
be discounted.
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Delay (Non-Operating Event) – An event
causing the dragline to stop
Dragline delays normally refer to reasons causing the dragline to stop working.
Delay is more frequently used when referring to the monitor coded reasons.
The following is an example of delay codes.
Code
30
Name
Power loss (blackout)
Code
Name
137
Lube system.
101
Maintenance inspections.
138
Boom/mast/a frame.
102
Routine pm service.
139
Air system.
103
Major shutdown.
140
Accidental equipment damage.
116
Power cable repairs.
141
Power loss.
117
Dump rope change.
168
Tritronics fault.
118
Drag rope repairs.
303
Equipment inspections
119
Hoist rope repairs.
502
Routine pm service - field
120
Electrical drag.
530
Sched - dump rope replacement
121
Electrical hoist.
551
Sched - misc mechanical repairs
122
Electrical propel.
583
In shift service
123
Electrical swing.
587
Scheduled maint
124
Electrical other.
588
Sched - planned major shutdown
125
Wait on labour - electrical.
700
Accident damage
126
Mechanical drag.
716
Tyres maintenance
127
Mechanical hoist.
741
Rope replacement/resocket
128
Mechanical propel.
742
Dump rope relacements
129
Mechanical swing.
751
Unscheduled maintenance
130
Mechanical other.
771
Wait on fitter
131
Wait on labour - mechanical.
772
Wait on electrician
132
Rigging repairs/change.
792
Wait maintenance
133
Bucket change - maintenance.
796
Wait on parts
134
Bucket get & adaptor repairs.
797
Cable damage
135
Control system (plc).
970
Not configured
136
Pm overrun.
983
Excitation off/ignition off
998
Uncalibrated ropes
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Summarised Best practice
machine stoppages are as
follows.
The key considerations
are;

Walking/maneuve
ring / positioning
 Scheduled
maintenance vs.
unscheduled maintenance
 Waiting on dozer
Each of these will be
covered in separate Best
Practice points to follow.
The key with scheduled
maintenance (and
as well) is optimising the
time spent stopped. A
general target of 500 hours
is set for annual scheduled
maintenance time
although achieving a total
maintenance time of less
than 800 hours per year is
the ultimate goal.
Sufficient resources should
be allocated to scheduled
maintenance to meet these
targets.
As the primary stripping
tool the dragline should be
given maintenance labour
priority. Scheduled
maintenance should have a
plan and it should be
followed. Most
activities will be
repeated/expected events and as such should be documented and
refined over time.
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In addition, best practice operations effectively manage their available
time to dig by minimising their operational delays through:




Hot seat changes. Dragline operators change over in
the dragline with no delay to
the operation.
Crews change with the operators so that there are no
delays caused due to waiting for crews to walk, for
dozing, etc.
“Double dipping” using delay activities to conduct
other work. I.e. walking the dragline out for stand
prep (bench/pad prep) and doing bucket
maintenance.
Two dig locations at all times
As well as stopping for as little time as possible the dragline should
stop as few times as possible. The average number of delays for all
dragline operations in the PwC Database is 30 per day. The ‘Best
Practice’ draglines have 15 stoppages per day. Every time a
dragline stops between 15 seconds and 3 minutes is lost. The average
is 60 seconds per stoppage. To be able to reduce the number of times
the dragline stops by 15 per day approximately 90 hours can be made
available for digging per year.
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Dig Face – The slope in front of the
dragline where the bucket is pulled into.
The dig face is the batter in front of the dragline where it is digging. It
is important to keep this face tidy to keep the drag ropes out of the dirt
when digging.
The face should not be undercut as it may create an unstable area
under the front of the dragline. Consequently, material can slump and
the dragline can end up sitting at the wrong angle.
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Dig Plan – How the pit will be dug with the
dragline
Good plans are essential. Mining / engineering plans should be timely,
accurate and achievable. The main objective when developing and
reviewing operational plans is to optimise the pit design and dig
methodology to achieve safe removal of the required volume of burden
(TCM’s, BCM’s, PBCM’s or BCYd’s depending on country), to the
correct location in the shortest possible time and/or the lowest unit
cost. The safe and efficient means of achieving this objective requires
detailed planning and scheduling, and relies on good communication
and co-operation between the Technical Services Department
(Planning), the Operational Superintendent / Manager, supervisors /
frontline leaders, and the crews.
Best practice operators and superintendents along with the frontline
leaders play an important role in the process of achieving business
objectives as their knowledge of the equipment capabilities and their
ability to anticipate and identify / manage problems has a direct
influence on delays, dig times and overall efficiency. Therefore, they
should play an active role in the development of the plan.
The best practice process for achieving timely, accurate and achievable
plans is;
1.
Have an experienced and competent planning engineer and
superintendent, or contract a consultant or consultants to help.
2. For every pit or bench the engineer and superintendent should
meet to discuss the excavation a minimum of a month ahead of
planned work.


Previous strip or block or bench in the same pit is reviewed
along with other relevant, subsequent issues.
Common understanding of the approach to be employed is
developed.
3. Engineer develops the draft plans for the pit using 3D (and maybe
2D as well) planning tools. The plans should include identification
of Dragline or Truck & Loader sequencing in the pit. Pit, strip,
blocks and loader locations should have a unique identifier.
Digging locations are provided in detail.
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4. Meetings are held amongst engineer, superintendent and
operators to discuss the draft plan. Some operations may include
frontline leaders.
5. Modifications made to plans and final plans issued.
6. Sign off by engineer, superintendent and operators. Agreement
that plan won’t be changed without specified procedure being
followed.
The minimum required plans are;




Strip or bench plan/s (plan view and cross sections) showing
blocks and spoil movement with key information marked.
Plans should include dates planned to be at points down the
pit for reconciliation purposes.
3D plans showing digging sequence.
Block plans showing planned digging and dumping locations.
3D animation of strip / bench excavation on designated
computer.
Typically these plans are discussed at a weekly planning level. This is
where a more detailed and short term view is able to be applied to the
machine performance prediction. At this stage of planning it is
possible to predict when and where planned maintenance will occur as
well as any major moves, meetings, or any other planned delays.
Therefore the targeting of planned output and rate is what should be
achieved on a given day or shift for average availability (excluding
planned work) and average utilisation (excluding certain unplanned
delays).
Planned performance may and will vary from shift to shift and day to
day depending on the inputs into the plan. The setting of targets is
about knowing what the potential for each piece of equipment is. This
has an internal and an external focus of what the same make and
model achieved in an earlier period of time and what it achieves
elsewhere. This allows capacity modelling for the piece of equipment
and the system as a whole. Typically the rate for the loading tool is
calculated from optimal cycle time and spot time. Assumptions are
made about availability that do not include significant downtime
events. Utilisation inputs are typically set at benchmark performance
although considerable care should be taken in accounting for
constraints.
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There is a history of dig plans not working well in the field. This is
partly due to the fact that much dragline planning has been done in
two dimensions and has failed to take “problem” areas
into account.
Dig Plan
on Paper
3G Dig
Simulator
3D Dig is a program that is being increasingly used by mines to assist
operations to design and dig pits. A computer on board the dragline
with 3D Dig enables the operators to follow a 3D computer simulation
of the dig plan.
Not only is a good plan essential, best practice operations hold
operators accountable for following plans and have systems in place to
respond when an operator thinks a plan should be changed. Key
actions are;
I.
Operators’ record digging location and details on their shift
report. Every time the operator changes digging location /
position of machine the change should be identified and
consistent with the approach specified on plans. Alternatively,
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GPS systems can be used to provide a record of the movements
and R.L (Reduced Level) information.
II.
Operators do their very best to follow plans, including, digging
and machine locations. Truck drivers position themselves to fit
in with loader technique. Bench/floor levels may be set using a
hand held or a machine mounted GPS device.
III.
Markers / survey pegs should indicate all key positions in the
pit, e.g. high wall, low-wall, end-walls, and block locations as
well as provide support for locating the loading unit and
getting R.L heights correct.
IV.
Superintendent checks pit layout, digging, machine
positioning and recording of operations every shift to ensure
compliance with plan.
V.
Operators are not authorised to change operations away from
plans except for immediate safety issues, e.g. geotechnical
issues, physical blockages, etc.
VI.
VII.
VIII.
IX.
Any other change in plan should be authorised by the
superintendent and should be agreed to by the operator,
superintendent and engineer.
Where feasible, the engineer should produce revised plans
ASAP.
Revised plans should be communicated to all crews.
The engineer and superintendent should visit each machine
daily to discuss any issues with execution of the plan.
Reconciliation of fleet performance is also essential. Ideally it should
be done based on volume moved and advance in the pit. The engineer
should prepare a plan showing the dates when certain points are
reached in the strip or bench. Actual progress is then marked.
If the equipment has not achieved the planned volume moved or linear
advance there are only three things which could have caused this;
i.
The equipment has underachieved either in payload and/or
number of cycles (these can be broken down further).
ii.
The plan wasn’t followed.
iii.
The plan was wrong.
Clearly the focus for planning is to establish a good plan, make sure
there is a process in place for ensuring compliance to the plan, and
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providing the mining department ongoing equipment performance
data and identifying where and when gaps in performance have
occurred. This will allow precise corrective action.
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Dig Rate – The amount of material moved
in a fixed time
Dig Rate is a raw measure of productivity which simply takes the
payload divided by the cycle time (tonnes/second) and converts it to
the unit of time required. Dividing by the in-situ SG converts the
weight (t) to a volume (BCM).
Dig Rate = (Ave. Payload/Ave. Cycle Time) * 3600 In Situ S.G.
Dig rate may also be referred to as BCM/Operating Hour. In this case
the total BCM’s moved in a period of time (hour, shift, day, week, etc.)
is divided by the operating time. Operating time has various
definitions but can be understood as the time available to operate after
maintenance, standby, idle, etc. are removed. The most common
calculation is the dig time plus operating delays.
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Dig Time – The amount of time spent
working productively (hours or
percentage of calendar time)
One of the key differentiators of best practice draglines is their dig
time. Best practice draglines spend more time digging productively.
Dig time is the number of hours (or percentage) the machine spends in
productive operation; excluding maintenance, process delays, walking,
etc. In practical terms dig time is broken down into number of cycles
and the time taken for each cycle.
Dig Time = (Total Swings * Average Cycle Time) / (Calendar time)
Dig time is highly correlated to annual output. Best practice draglines
generally achieve in excess of 6,500 dig hours per annum. This
equates to best practice dig hours/calendar time of 76%.
Of utmost importance is simply keeping a focus on the machine
swinging. Keeping the machine swinging can be broken into
availability and utilisation. It is imperative that best practice
operations understand where they lose time.
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Dig Zone – The area the dragline is
digging
The dig zone is the immediate area where the dragline is working. It is
worth considering anywhere within the boom point arc to be the dig
(or operating) zone. People entering this area should advise the
operator prior to entering.
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Diggability – How easy the bucket finds
the material to load
There are two aspects to diggability; material fragmentation and
bucket performance. The bucket needs to be set up with smooth faces,
sharp points and optimal geometry. Optimal Overburden
Fragmentation is essential for dragline productivity. As a general rule
a top size of no more than one third bucket width is required with a full
range of particle sizes. Monitors have recorded measures of diggability
but these have not been useful. The best measure of diggability is the
Specific Dig Energy.
SDE = Payload/Energy to Fill
As digging gets harder the payload goes down and the energy to fill
goes up. Hence the SDE goes down, and vice versa.
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Dilution – How much rock is mixed with
the coal.
Dilution of the coal is the percentage amount of overburden or waste
material mixed with the coal. There can be dilution within the coal
seam itself. The actions of the dragline operators when removing the
overburden from the top of coal can have a major effect on dilution.
Keeping the bucket off top of coal is one way of reducing dilution. The
dozer can push the last half metre for clean-up of the top of the coal
seam.
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Dip – Slope of the Coal
The dip of the coal is the angle the coal makes to the horizontal. It is
normal for dragline mines to start with the shallowest coal and follow
the seam “down dip”, i.e. the coal gets deeper as the mine progresses.
Draglines are normally employed where the dip is less than 10 0 but
there are isolated examples where steeper dip coal has been uncovered
by dragline. The steeper the dip the more difficult it is for the dragline
to fit the spoil in the available room and the more difficulty the
dragline has in meeting the toe on the highwall.
Dip
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Direct Cast – Material placed directly on
final spoil location
Direct cast is a dragline approach whereby material is placed directly
on final spoil location with very little rehandle. This approach has not
been used frequently in Australia. It was a predominant approach in
North America but has also reduced in popularity as mines get deeper
as they mature.
The direct cast method will generally result in narrower strips which
has implications for trucks used in coaling.
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Disengage – When the bucket is lifted out
of the overburden
The dragline is a unique digging apparatus due to the bucket being
controlled via two ropes which are joined by the bucket and rigging.
Sufficient forces should be generated in the rigging to lift the front of
the bucket out of the bank. These forces are a function of the angle
between the drag and hoist ropes.
Sweet
Spot
Roll
After Disengage
The bucket’s optimal disengage zone (usually over about 10 metres) or
“sweet spot” is governed by the length of the dump rope, and the skill
of the operator. Maintaining a roll at the sweet spot to pull the bucket
into helps disengage as well as fill the bucket.
Disengage a long distance from the drag fairleads results in excessive
nodding and material lost from the front of the bucket.
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Downtime (Delay) – The time the dragline
is not productive
Dragline downtime is normally the non-operating time of the dragline
for maintenance purposes. In some places it may refer to the total
amount of time that the dragline is not working. Refer to the entry
under “Delay”.
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Dozer – A tracked or rubber tyred
machine with a blade to push material
A dozer is a necessary ancillary tool around a dragline. It is used for
leveling the pad for the dragline and assisting in all areas of the
operation. Trimming high walls and cleaning the coal are but a few of
the tasks allotted to the dozer. The dozer operator needs a high level of
skills to perform the dozer work so the area is set up for working a
dragline efficiently. Dozers are used to push and lower benches in
dragline bench preparation (Dozer Assist).
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Dozer Assist – Work the Dozer Performs
that Assists the Productivity of the
Dragline
Dozer assist generally refers to a method of digging which involves the
dozer pushing spoil from a high wall to assist the dragline in its
productive ability. Some mines won’t allow the dozer to work under
high walls due to safety concerns. In all cases where dozer assist is
used the operator’s cabin will be fitted with a wire cage.
Dozer cleaning
High Wall
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Drag Brakes – Holding mechanism on the
drag system
The drag brakes are used to prevent movement of the drag function as
required. There are 2 types of brakes used, drum and disc. All brakes
are operated by the air supply and are designed to automatically apply
if the air supply fails.
Disk
Brake
Drum
Brake
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Drag Chain – Chains attached to drag
ropes
The drag chains connect the drag rope to the front of the bucket.
Chain is used due to the extreme duty which is experienced as they are
pulled through the ground. The weight of the drag chains is also useful
in dumping. There are usually between 17 and 24 links in each drag
chain depending on the full rigging configuration and the shackles
used at each end. The most common arrangement currently used is 19
drag chain links plus two pear links (one at each end).
Drag
Chains
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Drag Cluster – Joins drag chains, sockets
and dump chains
The Drag Cluster is a central part that joins the drag chains, sockets
and the dump chains. Different suppliers have different names for this
rigging part.
Drag Chain
& Shackle
Drag Cluster
Drag
Socket
Drag
Cluster
Dump
Shackle
Drag
Chains
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Drag Control Lever – Operator’s control of
drag function
The drag lever controls the drag function. The operator moves the
lever away to payout the drag, and pulls it towards them to drag the
bucket in. The operator uses the left hand to control
this function. Given that most operator’s cabins are on the right hand
side of the dragline the line of vision for the operator passes over the
movement of the drag lever to the movement of the drag rope.
Drag
Payout
Drag
Lever
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Drag Drum – Drum for reeling the drag
ropes
The drag drum is used to hold the drag ropes when reeling in and
paying out. On most draglines the drum closest to the front of the
machine is the drag drum. The easiest way to identify the drag drum is
to follow the rope off the drum. The rope going out the front of the
house is the drag rope which comes off the drag drum while the rope
going out the top of the house is the hoist rope which connects to the
hoist drum.
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Drag Gearbox – Drive speed reduction for
the drag drum
The drag gearbox is the drive reduction between the motors and drag
drum. The motors spin at high speed and this is reduced to the drum
speed through the gearbox.
Drag Gear
Box
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Drag Hitch – Where the Drag Chains
Attach to the Bucket
The drag hitch is the point on the front of the bucket where the drag
chains attach to the bucket. Positioning of the hitch is critical for the
best bucket performance. Some buckets have 2 hitch points. This gives
an adjustment for different digging conditions.
Drag
Hitch
To determine if a bucket is designed for optimum fill an analysis
should be performed on the bucket force distribution at engage. The
drag hitch location is a critical part of this. The aim is to determine if
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the bucket is set up correctly, particularly with respect to the drag
hitch height and the centre of gravity.
Bucket force distribution
The drag angle (of the ropes) can be calculated from;
tan-1 digging depth below the fairleads/horizontal distance
from the fairleads.
The greatest tooth force occurs when the line of action of the drag force
intersects the weight vector along the line of action of the tooth
resistance, that is, at the “ground point zero” directly below the centre
of gravity. Hence, the optimum drag hitch height (as measured from
the bucket floor line) will vary for different drag angles.
As the drag hitch height increases, the intersection of the lines of
action of the drag and tooth forces will move rearward from the
ground point zero. As a result, the centre of ground support will be
forward of the centre of gravity and the teeth will overly engage. The
limit of this is when the intersection passes the final ground contact
point, after which the bucket will flip forward onto its arch.
Conversely, as the drag hitch height decreases, the intersection will
move forward of the ground zero point and the centre of ground
support will be rearward of the C.G. This inhibits the teeth engaging
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until the limit is reached. At this point, the teeth will actually be pulled
out of the bank.
When digging deep spoil the line of action through the drag is steep,
(pink) and the teeth tend to pull out of the ground. When digging
shallow, the line of drag action is shallow and the back of the bucket
tends to topple over. This is a simple geometric and weight
distribution issue. More care is required when engaging very shallow
or very deep.
The magnitude of the tooth force when the drag hitch is at its optimum
height is:
R=W * cot (Drag Angle) (N.B. cot = 1/tan)
Thus, it is shown that, as the drag angle changes, the tooth force (and
optimum hitch height) also vary. To choose the correct hitch height,
an average for bucket engage position should be determined for a
digging block. For example, for the BE 1370W, this is approximately
50 – 60 m from the fairleads, with a 15 m digging depth. That is, a
drag angle of about 20-25˚.
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Drag Limits – An electronic cut-off to stop
the bucket being pulled into the fairlead
sheaves
The drag limits are an electronic control that stops the operator pulling
the bucket into the fairleads. As it is an electronic device it should not
be relied upon as the sole method of limiting drag motion as they could
fail. The operators are advised to modify their operating behaviours to
minimise using the limits to stop the bucket. Testing the limits is
recommended at the start of each shift to make sure they are
operational.
Most machines use 2 sets of drag limits; the ones that come with the
electrical controls of the dragline and the ones associated with a
production monitoring system, (e.g. Tritronics, Pegasus, and Aquila).
These production monitoring systems are used as the primary drag
limit control with the machine system as a backup.
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Drag Motor – Drive motors for the
drag function
The Drag Motors drive the drag drum through a transmission, i.e. the
gearbox.
Mid-sized draglines up to BE1370W/M8050 (45-50 CuM) use 1045 hp
drag motors while larger draglines tend to use 1300 hp drag motors.
The larger draglines have 6 and some 8 drag motors.
P&H 9020 Drag
Motors x 6
Marion 8050
Drag Motors
x4
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Drag Rope – Ropes used to drag the bucket
The Drag Rope is the rope passing through the fairleads in the front of
the house which attaches to the drag chains and are used to drag the
bucket to fill and are paid out to dump the bucket.
Drag Ropes
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Drag Rope Winch – Winch for pulling
drag ropes in to attach to drum
The Drag Rope Winch is used when replacing the drag ropes. The
ropes on the winch are connected to the drag ropes and then paid out.
At the same time a dozer or crane pulls the drag ropes to the ground
outside.
Drag Rope
Winch
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Drag Stall – When the load on the drag
motors is so great the bucket stops
Drag stall is when the bucket is bogged in the overburden to the extent
that the drag motors cease to rotate. The operator is in control of the
position of the bucket in the bank and should ensure the drag motors
don’t stall during the loading process. This is done by tensioning the
hoist system and holding the bucket at a depth in the spoil which
allows it to keep moving towards the dragline. Every stall creates a
burning effect on the motors and reduces the life of the motors. Should
a stall happen the operator should immediately reduce the power to
the motors while the hoist is used to lift the bucket. Some mines have
fitted a device that monitors the frequency of stalls. The following is a
drag motor plot for a Marion M8200. It shows the motors stalling
(speed = 0 feet per minute) at around 760,000 lbs (345 tonnes or
3,380 N) force.
Plot provided by Marion Power Shovel Company. Now owned by
Caterpillar Inc.
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Dragging – Function of pulling the drag
ropes and bucket
The dragline fills the bucket by pulling it towards the house. Dragging
is the action of pulling the bucket through the spoil to fill it. Generally,
it is done by pulling the left hand lever towards the operator; lever in
for dragging in.
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Dragline Access – Roadway to the
dragline for vehicle traffic.
Dragline access is the route that vehicles use to get to the dragline.
Priority consideration should be given to maintaining access to the
dragline as there are safety issues involved should an incident arise. All
roadways should be built and maintained to a high standard. The
route should always be clearly marked with the dragline designation.
Dragline
Access
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Dragline Monitors – Recording of dragline
information
There are a number of monitors used on draglines. For production
data there are Tritronics (Leica), Pegasys (Mineware), Aquila (Cat) and
Accuweigh (DCS). Some older machines may still have ISI and Contel
monitors. Machine stress monitors are becoming more common.
These include MTI, Max (LC Engineering), Pegasys (Mineware) and
WBM.
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Dragline Ramp – Walk road for the
dragline to move from one level to
another.
A dragline ramp is the walk road to walk the dragline from one level to
another. Where possible, ramps should be established prior to the
dragline arriving to use it. Most draglines have a maximum % of grade
for walking on. Check the mine site standard for your dragline.
Most ramps are built to a maximum of 10% grade. The ramp width will
depend on your dragline spec, but ensure there is ample room to
maneuver the machine should the occasion arise.
Dragline
Ramp
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Dragline Whiteboard – Message Board
on Dragline
The Dragline Whiteboard is used to write messages for the oncoming
crew. On some mines, it is also used to draw a short term “mud map”
of the pit or dig plan for the operators to follow.
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DragSim – RungePincockMinarco Ltd
DRAGSIM reports on the volumes involved and calculates accurate
and reliable productivities and re-handle. It reproduces dragline
mining methods across a range of operational parameters,
incorporating blasting, waste stripping and other mining equipment
into the analysis to better simulate actual operations.
DRAGSIM’S Windows interface makes it easy to perform accurate
analysis of production costs and productivity.
With DRAGSIM, you can compare different draglines before you buy,
or improve the operation of your existing dragline, by investigating
different practical work scenarios.
http://www.rpmglobal.com/mining-software/dragline-simulationdragsim
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Drift – A Tool for Removing Bucket Teeth
A Drift is a tool for removing the keeper pin that holds the bucket teeth
onto the adaptor. Manufacturers’ designs of teeth are different so
designs of drifts are also different.
Drifts
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Dump – Emptying the bucket
Dumping is the process of emptying the dragline bucket. After loading
and swinging the bucket to the spoil area the drag is paid out. This
action reduces the angle between the hoist ropes and the drag ropes
with the loading in the dump rope reducing. When the load in the
dump rope reduces the weight in the front of the bucket causes it to
drop (rotating around the hoist trunion) and the spoil falls from the
bucket under gravity.
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Dump Block – The outer casing that holds
the dump sheave
The dump block is the heavy, outer casing that houses the dump
sheave. There have been numerous designs for the dump block and
the upper rigging. One method employed to reduce rigging weight has
been to integrate the dump block into the miracle hitch (the
component which joins the hoist ropes and the upper hoist chains).
This however, reduces the degrees of freedom in the upper hoist
rigging and consequently may increase external wear on the dump
rope.
Dump
Block
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Dump Equaliser – The Bar that Equalises
the Dump Chains
The dump equaliser is a bar that connects the two dump chains and a
single dump rope. A dump equaliser is not required where a double
dump rope rigging is used.
Dump Equaliser
Dump Chains
Dump Rope
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Dump Height – The height from bottom of
the tub to the bottom of the teeth when
dumping
Dump height varies depending on where in the block the dragline is
digging. As a general rule the dragline should dump at the lowest
height the spoil will allow but not below tub level as this increases
loading during dumping. The dump height (defined in the dragline
specification) is the maximum height the dragline can dump above tub
level.
The maximum dump height is an extremely important geometry
driven consideration in designing a dragline digging sequence. It is a
physical limitation of the machine which, along with dump / operating
radius define where material can be dug from and where it can be
placed.
Dump
Height
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Dump Radius (Operating Radius) – The
specified dumping distance from the
dragline
The specified dump radius is the horizontal distance from the centre of
the tub to the boom point. This is the theoretical point of dumping of
the bucket.
In the field most operational people measure the dump radius from the
front of the tub, not the centre of the tub. Dragline engineers and
operational people need to be aware of this difference in
interpretation.
Planning engineers use the dump radius to plan tub locations and
dumping volumes. Planning engineers normally assume the bucket
always dumps spoil under boom point and this may not be a correct
assumption. Many operators dump the spoil inside boom point due to
the difficulty in keeping spoil in the bucket at boom point and the fact
that the motion of the bucket projects the spoil back towards the
house. A major difference occurs between plans and operation
(causing higher than planned rehandle) when the spoil is not placed
predominantly under boom point. This creates spoil room problems.
Operational
Dump Radius
Specification
Dump Radius
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Dump Rope – The steel rope that
facilitates the dumping action
The dump rope is attached to the dump chains (double dump rope) or
dump equaliser (single dump rope) at one end and the bucket (via the
lug on the arch) at the other. This rope facilitates the dumping action
as it is the rigging component which effectively connects the drag and
hoist systems. The rope can be cut from a used hoist rope however
many mines now purchase new dump ropes. The length of the rope
between the sockets changes the carry angle of the bucket. At the
correct length the dump rope facilitates the bucket being disengaged as
soon as the bucket is full for much of the time thus decreasing the cycle
time. Maintenance and production people need to work together to
achieve the best results.
Dump Rope in
carry mode
Dump Rope in
dump mode
The dump rope is the weakest link in a dragline bucket’s rigging.
Anecdotal evidence from mines suggests that dump rope life
expectancy has shortened from three to four weeks in the 1970’s to one
or two weeks today. The reasons for this are not clear although the
following 5 factors have been identified which are critical to dump life:
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1.
2.
3.
4.
5.
Ratio of dump block sheave diameter to dump rope diameter
Excessive loads in dump rope, particularly during disengage
Rope abrasion against dump block
Rope abrasion against bucket
Dump rope construction
Dump rope construction is something which rope manufacturers are
working on. Some mines are now using 8 strand ropes rather than the
more traditional 6 strand ones. Reports suggest that the new ropes
have a marginally longer life.
The other 4 factors identified in the report all contribute to dump rope
wear which eventually results in breakage if not changed out. The
interaction between these factors is complex and not fully understood,
but for the purposes of defining the problem they can be thought of as
contributing to two kinds of dump rope wear or damage: internal
damage and external damage.
External damage can be thought of as the abrasion and impact the
outside of the rope suffers when it comes into contact with other
objects such as the dump sheave housing, the dump sheave, the bucket
and highwall (during chopping). This type of damage is affected
predominantly by factors 2, 3, and 4 listed above.
Internal damage can be thought of as the wear caused by individual
strands of the rope rubbing together primarily during bending. This
will result in abrasive wear of strands or fatigue failure if the strands
are bent excessively. Factors numbers 1 and 2 are the principal cause
of this type
of damage.
It is logical that external wear will have less relative effect on a larger
diameter rope than on a thinner one as it will take less time for
impacts and abrasions to wear through a thinner rope. It is likely that
this is the reason why dump ropes have increased in diameter over the
last 20 years.
What is less obvious is that for a fixed diameter sheave, a thicker rope
suffers far more internal damage than a thinner rope. In fact for a thick
rope moving around an excessively small sheave (low D:d ratio) the
internal damage will cause failure much sooner than the external wear
would. Choosing the correct rope diameter that balances the need to
resist premature failure from external damage versus failure due to
internally induced damage is not an easy thing to do. The following
figure illustrates this problem. This chart shows the relationship
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Rope Damage
between internally and externally induced rope damage versus rope
diameter for a dump rope passing over a fixed diameter sheave.
Total Damage
Minimum
Internal Damage (Bending)
External Damage (Impact)
Optimum
Rope Diameter
Dump Rope Damage Versus Rope Diameter for a Fixed
Diameter Sheave.
It can be seen from the graph that large diameter ropes fail primarily
due to the internal damage of running around a relatively small sheave
(low D:d ratio) whereas smaller dump ropes (high D:d ratio) fail
primarily due to the external damage they suffer. Usually the total
damage suffered by a rope (reduction in strength) is combination of
both types of damage and somewhere between these extremes there is
an optimal diameter rope (for a given sheave diameter) that maximises
rope life.
The following table shows the predicted life for internally induced
damage (using Australian Standards AS1418.1) for a variety of rope
diameters bearing a load of 100 tonnes passing around a 1220 mm
diameter sheave. This is a typical configuration for an Australian
dragline. It can be seen that the breaking load of a new 57 mm
diameter rope can easily manage the 100 t load. However the
interesting point from the table is that the predicted life for the ropes
decreases dramatically as the ropes get larger. The predicted life for
the 83 mm diameter rope is 17.7 days.
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Indicative Design Life vs. Dump Rope Diameter for 1220 mm
Diameter Dump Sheave
Rope Diam
Breaking
Load
(tonnes)
Safety
Factor
D/d 1040mm(41”)
Sheave
Design Life
(days)
57mm
240
2.4
21.4
64.4
64mm
300
3.0
19.1
44.2
70mm
360
3.6
17.4
28.5
76mm
430
4.3
16.1
22.8
83mm
500
5.0
14.7
17.7
This table suggests that a smaller diameter rope should last longer. It
is known however, that a 57 mm diameter rope will not last 64.4 days
in most operations. It is also known that most 83mm ropes won’t last 2
weeks consistently. This again supports the fact that external damage
plays a major role in the life of dump ropes.
It has been demonstrated that the load carried by a rope affects its
useful working life - this is particularly so when a rope passes around a
sheave. There is little published data on dump rope loads. The major
knowledge is as follows:







the rigging geometry can cause different loads in the dump
rope,
bucket geometry does cause different dump rope loads,
the load in the dump rope is more dependent on bucket
location than load carried,
loads in dump ropes for BE1370W and M8050 class machines
are mostly below 50 tonnes but can exceed 150 tonnes during
disengage at the drag limits and during the swing part of the
cycle,
the most rapid dump rope loading occurs during disengage,
the highest loads experienced by the dump rope are about one
third to one half the way up the boom on the tight line
envelope, and
there is a relationship between dump rope load and hoist rope
load.
It is well known that the majority of internal and external damage
occurs while the dump rope is passing over the dump sheave. The
magnitude of the damage is a function of the load in the rope and the
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speed of the rope. It appears that in the drive to increase dragline
productivity, through high productivity buckets, reduced rigging
weights and different digging techniques, the rope life has been
sacrificed as a necessary part of the improved productivity.
A significant contributor to rope life generally is lubrication.
Lubrication of dump ropes is not practised widely due to concerns of
grit penetrating the rope and actually reducing life.
Many mines now have larger draglines which require a double dump
rope arrangement. A series of “rules” have been developed to set
double dump rope rigging up correctly and for management to
evaluate options brought to them by suppliers.
1.
2.
3.
4.
5.
Connect dump ropes to the bucket arch with the maximum
separation possible.
Design the upper spreader arrangement to ensure the dump
block separation is equal to the dump rope lugs on the arch.
Allow the widest possible separation of upper hoist ropes both to
the lower spreader bar and the upper spreader arrangement
Allow maximum degrees of freedom of the dump blocks
Minimise weight while maintaining structural integrity
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Dump Sheave – The dump sheave holds the
dump rope
The dump sheave is a large pulley which the dump rope passes over
and allows the dump rope to move freely during the dumping and
disengaging processes. The sheave is encased in a fixed outer casing
which is called the dump block.
Dump
Block
Dump
Sheave
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Dump Time – The time it takes to dump the
load out of the bucket
The time spent dumping the load from the bucket. It is very difficult
for monitors to accurately identify dump time as the commencement
of dumping is difficult to pick from hoist rope load. The end of dump
is easy and is a key identifier of the cycle. Most monitors include
dump time in the swing and/or return times. Dump time is neither
used as a KPI of operator nor machine performance because it is
difficult to quantify. See charts included in cycling to see that the hoist
load change is not a clear indicator of the start of dump, nor is swing
direction, drag rope movement and hoist rope movement.
Consequently, dump time is important but the overall swing and hoist
times are more important and dump should be considered as a subset
of one or both of these.
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Dumping on the Fly – Dropping the
material out of the bucket while swinging
This action is normally associated with draglines swinging through
3600, i.e. a complete circle as opposed to swing, dump and return.
Dumping on the fly involves paying the drag ropes out while still
swinging the dragline. Stresses on the boom can be increased because
the bucket will normally be outside the boom plane. This practice is
acceptable under certain conditions providing it is controlled correctly
by the operator. If a dragline is required to swing 180 0 to dump and
the pit arrangement supports it dumping on the fly during a 360 0
circle with the bucket can improve cycle time as deceleration to dump
and acceleration after dump are eliminated. Most operators are not
able to do this while keeping the bucket under the boom so careful
consideration is required by the mine before allowing it.
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Dust Control – Reducing dust while
digging
Some dragline operations use large hoses to spray water around the
dragline digging area to keep dust levels down. Dust is a major
problem at some mines with significant periods of standby time caused
by poor visibility from dust. The problem may be magnified at night
where still conditions can cause dust levels to increase.
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Dyna-Vanes – The structure that channels
the air into the dragline house
Dyna-vanes are the primary dust/dirt filtering system for air entering
the house.
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Earth Grid – The electrical earthing mat
for the dragline substation
The earthing grid for the dragline substation is dug into the ground to
give earth continuity to the power grid. In dry weather, a water truck is
used to flood the earth grid to assist with continuity. Beneath the earth
grid a number of copper rods are buried deep into the ground.
Typical Earth Grid
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Elevated Bench – A leveled area built
higher than the surrounding bench
An elevated bench is the practice of a dragline (with dozer support)
building a bench higher than the bench it is sitting on. Most elevated
benches are built on the low wall side to increase the spoil room
available. An elevated bench is often (but not exclusively) associated
with pullback.
Elevated bench
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Encoder – Encoders send signals to the
monitor
Encoders are devices that send signals from different functions around
the dragline to the monitor.
Encoders are mounted in a range of locations around the dragline
depending on recording systems installed. For example, a production
monitor will have them on the hoist and drag drums, and the swing
gearbox. They allow the monitor to electronically interpret where the
functions are at any given time.
Encoder
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End wall – The face at the start and end of
the strip
The end wall is the dragline dig face or opening face at the end or start
of a strip.
The strip starting end wall is usually at the same angle as the high wall,
whereas the completion end wall is between 45 and 50 degrees as the
dragline finds it difficult to dig it steeper and it can create an unstable
bench for the dragline to sit on.
Pit Completion
End wall
Pit
Beginning
End wall
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Engage – When the bucket is first pulled
into the overburden
The bucket is engaged at the back of the block so the bucket stays
behind the overburden. Every time the bucket is pulled into the bank it
is engaging the overburden.
Back of Block
Bucket engaged at back
of block
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Equivalent Annual Production
Equivalent annual production assumes a complete 7 day roster with no
stoppages longer than a nominal length (usually 7 or 14 days). It can
be divided by in-situ SG to convert tonnes (weight) to volume.
Equivalent Annual Production =
Annual Swings * 365
* Ave. Payload
(365 – Stoppage days > 7 days)
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Esco – Bucket and rigging manufacturer
ESCO is a
manufacturer of a
range of dragline
buckets, rigging and
accessories. They
have a long history
with dragline buckets
including MkIV, MkV
(HDL), MkVI (MM)
and Production
Master. More recently
Esco have sold the Pro
Fill buckets. Esco are
continuing to develop
new designs.
Old style Esco dragline bucket
ProFill® Dragline bucket
http://www.escocorp.com/EN/products/Pages/profill-draglinebucket.aspx
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Excitation – The function that starts
the motors
Excitation is the process of powering-up the motors. On a dragline
this is an energy-intensive process and notice is normally required for
the power supplier to be ready.
Excitation
Button
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Excitation Isolator – The isolation point
for the excitation
The excitation isolator is the isolation point for the excitation. This is
the ultimate point where the power can be stopped from reaching the
motors. Generally used during maintenance to stop excitation while
work is being done.
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Extended Bench – The method of building
a bridge away from the high wall
Due to the physical limitations of the dragline often an extended bench
should be built to allow the dragline to reach the required spoiling
location. On many occasions this bench may extend to the low wall.
Extended
Bench
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Extended Keys – A long key cut extending
through multiple blocks
A key cut is often the first part of the block dug which exposes the
highwall down to coal level. Extended keys are a series of slots or keys
dug along the high wall over multiple blocks before digging the
remaining spoil from the blocks. This is one of the options used when
coal mining operations are not waiting for coal to be uncovered as no
mining can be done until the dragline completes the series of keys and
comes back on the low wall bench and exposes the coal on that side.
The extended key material is dumped to create the low wall bench.
When spoil room is tight this bench can be elevated to create more
room.
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Extractor Fans – Remove hot air and dust
from the house
The extractor fans are located around the machinery house and assist
with the removal of the hot air and dust from the house.
On a BE machine, they are located on the walls of the house.
The Marion machine extractor fans are located on the house roof and
are primarily used to extract the dust from house.
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Fabricated Bucket – A bucket made almost
entirely from quenched and tempered steel
A fabricated bucket uses quenched and tempered steel in all areas of
the bucket. The steel is cut and rolled to shape to be welded together
into the dragline bucket shape. Generally the only part of a “fabricated”
bucket not fabricated with Q&T steel is in the front lip which is
normally cast although the lip can also be fabricated. A fabricated
bucket is usually identifiable through the rectangular cross section of
the arch. A cast bucket normally has a cast arch which has a round or
oval cross section.
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Fairlead Buffer – Device to minimise
excessive fairlead movement
The fairlead buffer is a device that helps to prevent the fairlead
assembly from swinging wildly from side to side during operation,
causing potential structural damage.
The Marion draglines were designed with a braking system while the
BE machines have a hydraulic system.
Some mines have altered the systems and use alternative materials
including rubber and plastic.
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Fairleads – The pulleys that guide the
drag ropes in and out of the house
Fairleads are the sheaves the guide the drag ropes into the house and
the drums.
The fairleads have sideways movement to keep the ropes lined up with
sheaves so they don’t come off.
The arrangement of the fairlead sheaves varies with make and model
as well, as size of the dragline.
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Fan House – Structure on top of the
dragline that holds the pressurising fans
The fan house holds a series of fans that pressurise the dragline house.
The air entering the house is filtered to a certain extent to keep the
dust out of the machine
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Fatigue – One of the two types of stress on
the dragline structure.
If you repeatedly apply and then removed a nominal load to and from
a metal part (known as a "cyclic load"), the part will break after a
certain number of load-unload cycles, even when the maximum cyclic
stress level applied was much lower than the strength of the member.
As the magnitude of the cyclic stress is reduced, the part will survive
more cycles before breaking. This behaviour is known as "FATIGUE"
because it was originally thought that the metal got "tired". When you
bend a paper clip back and forth until it breaks, you are demonstrating
fatigue behaviour. On a dragline the cyclical action of dig, swing, dump
and return creates many fatigue situations around the machine.
Fatigue life is a fixed quantity, and is always being used. The questions
are:


How fast is the available fatigue life being used?
What are the critical crack lengths compared to
inspection strategies?
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Fault – A Fracture Zone in the Overburden
http://en.wikipedia.org/wiki/Geologic_fault
In geology a fault, or fault line, is a planar fracture in rock in which the
rock on one side of the fracture has moved with respect to the rock on
the other side. Large faults within the Earth's crust are the result of
differential or shear motion and active fault zones are the causal
locations of most earthquakes.
Since faults do not usually consist of a single, clean fracture, the term
fault zone is used when referring to the zone of complex deformation
that is associated with the fault plane. The two sides of a non-vertical
fault are called the hanging wall and footwall. By definition, the
hanging wall occurs above the fault and the footwall occurs below the
fault.
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FD – Factor Diggability
FD is used in the calculation of Specific Dragline Output. It is an
allowance for the difficulty which a spoil is finding the spoil to dig. A
competency scale has been developed using the SDE to measure how
difficult the spoil is to dig. Using this scale, the following factors have
been calculated using the PwC dragline performance database [Contact
PwC for the latest numbers]. They allow spoil impact on productivity
to be accounted for.
Bucket Design
Competency
5
4
3
2
1
Conventional
1.13
1.09
1.00
1.00
1.00
Scoop
1.28
1.13
1.00
0.99
0.96
UDD
1.16
1.04
1.00
0.99
0.99
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Fill Distance
Fill Distance is the distance between the locations where the bucket is
engaged and where it is disengaged. It can be calculated with sufficient
accuracy as the hypotenuse of the engage and disengage points from
the monitor data although the exact formula is more complex and is
the change in drag rope payout between the two points.
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Fill Sink – Backfill the area when the
dragline has sunk.
The dragline is a heavy machine, and it will sink when it sits on
unconsolidated material. When the dragline sinks, it has to be walked
out and the sunken area backfilled with the dozer using competent
material. When the area has been leveled the dragline walks back and
continues digging. Be cautious to have a smooth pad under the
dragline to provide constant support for the tub.
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Fill Time – The time taken to fill the bucket
Fill time is the time it takes to fill the bucket. It is the time from
engaging (when the drag load rises rapidly) to disengaging (when the
hoist load rises rapidly). Best practice draglines fill the bucket in 14-16
seconds.
The fill time is not as important a KPI as payload. Consequently the
payload should never be sacrificed to reduce fill time.
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Fire Extinguisher – A tool used for
controlling fires
Fire extinguishers are a pressurised cylinder that is used to control
small fires around a dragline.
The most common used is a dry powder, and can be used around
electrical components.
There are periodic statutory checks required on all extinguishers.
Mine personal are also required to have regular training and refresher
sessions on how to use a fire extinguisher.
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Fire Panel – Electrical panel that monitors
and controls fires in the dragline
The fire panel on a dragline monitors and when required controls the
fire.
Smoke Sensors are placed in various parts of the dragline and a
cylinder of oxygen depleting gas is stored for use.
The fire panel controls the release of gas as required.
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Flipping the Bucket – Turning the bucket
upside down
Sometimes it is possible to twist ropes and turn the bucket upside
down. It is not a serious issue provided no ropes are fully loaded while
twisted. Picking the bucket up will generally rectify this problem.
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FMM – Factor Make and Model
Anecdotal information and dragline productivity data indicates that
different draglines do perform at different rates. Physical reasons for
the differences among makes and models are most likely a function of
the electrical system set up on the individual draglines. The electrical
system includes drag, swing, hoist and walk. As an example, if drag
motor performance is reduced more difficulty will be encountered in
filling the bucket and reduced payloads can be expected.
The average performance of the top decile of draglines in each class
has been compared against the average of the top 10% for all draglines.
These factors will change on a periodic basis based on available data.
The factors should be used when comparing different dragline makes
and models.
[Contact PwC for the latest numbers]
Dragline Classes
FMM
Marion 8050
0.981
Marion 8200
0.961
Marion 8200S/8750
1.067
BE1260W/1300W/1350W
1.155
BE1370W
1.018
BE1570W
1.011
BE2570W/2570WS
1.140
P&H9020
1.234
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Fragmentation – How Well the
Overburden is Blasted
Fragmentation is effectively the particle size distribution after blasting.
It is an assessment of how well the overburden is fractured or broken
up. Good fragmentation of the blasted overburden is when the dragline
can fill the bucket easily with a good heap of spoil on the top.
Overburden can at times be over fragmented (powdered) and it will
tend to flow out of the bucket without heaping.
Good Fragmentation is when the particle rock sizes range from fines
up to around one third the width of the bucket.
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Front Ring – The front structure of the
bucket
The front ring of a dragline bucket incorporates the lip, cheek, drag
hitch and the arch. The lip is usually cast but the rest of the front ring
can be cast or fabricated.
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FSA – Factor Swing Angle
FSA is used in the calculation of SDO.
Variations in swing angle can have a significant impact on dragline
cycle time (time from the start of fill to the next start of fill) and hence
productivity/unit time (i.e., when swing angles are larger, the dragline
does fewer cycles in the unit time). Swing angle varies between 60o
and 180o giving a variation in cycle time of up to 30%. The correction
for swing angle will be based on the difference between the actual
swing angle and a reference swing angle and the impact that difference
has on the cycle time. The reference swing angle is chosen as the
average for the whole industry.
FSA
=
1
+
2 * ( SA ref –SAave)
_________________
SRpeak * CTave
Where
FSA
=
Factor (swing angle)
SAref
=
Swing angle reference (degrees)
SAave
=
Swing angle average (degrees)
SRpeak
=
rate (degrees/second)
Average of peak Swing rate and peak return
CTave
Cycle time average (seconds)
=
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G.E.T – Ground Engaging Tools
By definition ground engaging tools are any tool which engages the
spoil. On dragline buckets G.E.T‘s are the replaceable/wearing parts.
Ground engaging tools include teeth, lip, shrouds, wear defence, and
the bucket itself.
These parts wear out relatively quickly as they are constantly in contact
with the overburden as the bucket is dragged through it.
It is very important to understand that GET should not be seen as just
about having “something” to wear out in place of bucket structure but
proper GET is about the bucket performance (payload) being
optimised.
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Acceptable but not optimal GET use.
The 3 Figures above demonstrate acceptable GET management. The
most important aspect for GET is that all parts of the bucket presented
to the spoil should have an edge and preferably a sharp edge. This
includes having teeth and adaptors in place (replaced when knocked
off) as well as shrouds on all flat faces between the teeth and on the
cheeks. The cheek shrouds should extend from the top of the corner
tooth to the underside of the drag hitch as shown.
Optimal cheek area set up
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GET life cycle is dependent on material type, internal angle of friction,
material diggability/fragmentation, and installation process. These
three areas impact life cycle and replacement of worn or sub optimal
GET should be conducted without delay on daily services, bucket
services, and or monthly maintenance outages to maintain best
practice performance..
As already discussed, a critical aspect of GET is the tooth and lip
arrangement. The rule for tooth and lip arrangement is the face of the
tooth should run down the centre line of the tooth. In cases where
there is a physical limitation (e.g. Sidewinders or other side pinning
system in the adaptors) the face of the lip shroud should be parallel to
the centre line of the tooth and as close to the centre on the underside
as possible.
Close to optimum position for tooth and lip arrangement with
Sidewinders.
Optimal bucket performance requires wear defence to be minimised.
This includes on the GET. Rough edges and oblique faces increase
friction between the bucket and the spoil adding to the drag force and
increasing the effort required to push the spoil into the bucket. The key
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to this is that the GET should be allowed to wear and should be seen as
a consumable item.
Incorrect wear defence on GET
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Correct wear defence on GET
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GAL – Gross Allowable Load (same as
Rated Suspended Load)
The Gross Allowable Load is the same as Rated Suspended Load
(RSL). The GAL or RSL is the average load carried by the dragline and
includes payload, bucket weight and rigging weight. A distinction may
be drawn between Gross Allowable Load and Maximum Allowable
Load. GAL is the average of all loads while the MAL is the absolute
maximum the supplier specifies that the dragline should carry. The
MAL has been incorrectly specified by some suppliers as being too
close to the GAL. Each dragline owner is recommended to undertake
independent assessments of their dragline structures using dynamic
loading models which can now be obtained from stress/damage
monitors.
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Gantry – Attached to the A Frame
The gantry is positioned on the mast and the A Frame to provide
access. The bottom of the gantry attaches to the main chassis of the
dragline at the front of the revolving frame. The top of the gantry is
supported by the A frame at the rear and attached to the mast in the
front.
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Geology – The structure of the earth
Geology is a region or stratum distinguished by composition or content
of the overburden. The geology of the coal and overburden is very
complex at times.
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Gravel – Surface Material for Roadways
Gravel is a stony mix of material used to surface roadways and prevent
excessive surface break up under heavy traffic use. Crushed basalt or
similar hard igneous rocks are common roadway gravels used.
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Guide Post – Delineates Roadways
Guide Posts are used on a mine site to delineate roadways.
Most guide posts used are various lengths of white PVC pipe with
reflectors attached. 3metre lengths of PVC are used on haul roads to
make it easier for the large trucks to see the edges of the road.
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Haul Road – Roadway for Large Trucks
Haul Roads are built to withstand the heavy loads carried by haul
trucks. The specification for a haul road has to be a minimum 3-1/2
times wider than the width of the largest truck using it.
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Hazard – Something which may result in
injury or harm
Safety around a dragline operation is paramount at all times. The
identification of hazards is critical in incident prevention. It is the
responsibility of all mine employees to identify and control hazards in
the work place. The most common cause of lost time injuries on the
dragline are falls while getting on and off and slamming doors from the
pressurised house.
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Heat Map – Identifying high potential
areas for productivity improvement
A heat map is a technique for identifying where effort should be placed
when considering opportunities for productivity improvement. There
is no fixed form as to what should be produced and how it should be
displayed. The aim is to break the dragline productivity into as many
constructs as desired and then develop a methodology for determining
the cut-off values for good / average / poor performance. This could
be against some average (either machine or industry) or against an
industry benchmark.
The following figure is a sample heatmap. This particular example
focuses on the digging and the payload achieved as this is where most
value may be extracted.
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High Wall – Wall left in undug overburden
The high wall is the advancing wall of the pit left in undug overburden.
The angle of the high wall (Batter) can vary at each mine site. In
competent material the angle is usually 70 degrees, but it can be 60
degrees or even as low as 45 degrees. Some mines cut vertical high
walls. This can create a safety issue for people working under it or on
it.
Some mines also presplit their high wall. When done correctly this
practice creates a very clean, stable wall.
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High Wall Failure – Unstable wall or parts
of it
A high wall is said to have failed when part of it falls into a previously
dug out pit. Can be a major hazard when equipment is working in the
vicinity.
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High Wall Key (Key Cut) – Trench dug
exposing the high wall
A High wall key or key cut is the term for a trench dug by the dragline
exposing the high wall. A high wall key is used in a key/bridge, and
extended key method of operation.
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High Wall Trim – Approximately a bucket
width left on the high wall.
A key cut may not be dug right on the high wall. An inside key may
leave material on the high wall batter that is either removed by the
dragline or the dozer at a later point in the block.
Other dig methods may leave spoil on the high wall for removal by the
dozer.
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Historical Data – Information from
previous strips
Significant knowledge is accumulated through experiences at a
particular operation. Historical data is information gathered by
various means and archived for future reference. Data is gathered by
machine production monitors, engineers and production personnel in
hard or electronic copy, and is a very useful means of verifying things
that may have happened during the excavation of previous strips.
Sometimes historical data is lost due to the movement of key personnel
around site or to other sites and this needs to be planned for.
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Hoist Brakes – Holding mechanism on the
hoist function
The Hoist brakes are used to prevent movement of the hoist function
as required.
There are 2 types of brakes used; drum and disc. All brakes are
operated by the air supply and are designed that should the air supply
fail the brakes will automatically apply.
Hydraulically operated disk brakes are now available. They are more
efficient in operation and require less maintenance.
Drum
Brakes
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Hoist Chains – Upper and lower hoist
chains
The hoist chains carry the bucket and payload. It is made up of 2
sections, upper and lower, with the spreader bar in the middle. The
hoist chains are a major contributor to rigging weight. The weight of
the hoist chains should be optimised (reduced) without reducing
maximum bucket movement to less than 45 degrees and -90 degrees.
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Hoist Control Lever – Control for lifting
and lowering the bucket
The Hoist Control Lever controls the hoist function. It is on the right
hand side as the operator sits in the seat.
The operator moves the lever away to lower the bucket and pulls it
towards them to hoist the bucket up.
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Hoist Dependent – When the operator has
to slow swing for the bucket to reach
dump height
A hoist dependent cycle is when the operator has to reduce the swing
motion to allow the hoist enough time to reach the required dumping
height. This usually arises when the dragline is sitting relatively close
to the spoil pile and spoil room is tight.
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Hoist Distance
Hoist distance is the distance the hoist rope travels between the points
where the bucket is disengaged and where it is dumped. The
calculation of hoist distance from production data is a complex
calculation of the change in hoist rope payout length between
disengage and dump points. The hypotenuse of the disengage and
dump points from the monitor data does not provide sufficient
accuracy.
Production monitors use the measured hoist rope movement to
calculate the disengage and dump points but don’t report the hoist
rope (or drag rope) movement off and on the drum.
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Hoist Drum – The drum that the hoist
ropes are wound on
The hoist drum is used to hold the hoist ropes when reeling in and
paying out. On most draglines the drum furthest from the front of the
machine is the hoist drum. The easiest way to identify the hoist drum
is to follow the rope off the drum. The rope going out the front of the
house is the drag rope which comes off the drag drum while the rope
going out the top of the house is the hoist rope which connects to the
hoist drum.
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Hoist Gearbox – The drive speed reduction
between the motors and drum
The hoist gearbox is the drive reduction between the motors and hoist
drum. The motors spin at high speed and this is reduced to the drum
speed through the gearbox.
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Hoist Limits – The electronic cut-off to
stop the bucket being pulled into the boom
point sheaves
The hoist limits are an electronic barrier which stops the bucket being
pulled into the boom point sheaves. This cut off point is usually set so
the hoist is referenced (slowed down) at 5 metres and stops the inward
hoist movement at 3 metres from boom point. The operator needs to
be aware of the individual site machine specifications. Limits should
always be reset after the hoist ropes have been changed or re-socketed,
and before the machine returns to service. The operator should check
the limits at the start of the shift to make sure they are operational and
according to specifications.
When high spoiling the operator should not use the electronic limits to
stop the hoist. They should make it their business to slow the hoist to
its limits.
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Hoist Motors – Drive the hoist system
The hoist motors drive the hoist function. Mid-range Marion & BE
draglines have 4 hoist motors, while the larger draglines can have up to
8 hoist motors. Most hoist motors on mid-sized and large draglines are
1,045hp or 1,300 hp each.
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Hoist Rope – Used to lift the bucket.
The Hoist Rope is the rope which passes out the top of the house, along
the boom, over the sheaves and connect to the hoist chains which hold
the bucket. Most medium and large draglines have two hoist ropes
although some of the larger, older draglines had four hoist ropes.
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Hoist Rope Guide Rollers – Guide hoist
ropes on exiting the machine house.
These rollers guide the hoist rope into and out of the machine house.
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Hoist Rope Winch – Used when replacing
hoist ropes.
The hoist rope winch is used when replacing the hoist ropes. The ropes
on the winch are connected to the hoist ropes and then paid out.
Depending on the boom configuration some hoist ropes will pull out
under their own weight while some will need to be pulled out with the
dozer or crane.
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Hoist Trunnion – Where the lower hoist
chains attach to the bucket.
The hoist trunnion is the mechanism by which the lower hoist chains
are attached to the bucket. Some trunnions are designed with 2 holes
to enable the hoist chains to be attached in the front or rear position.
These positions allow a further adjustment for different carry angles
and dump adjustment. Anecdotal evidence is that very few operations
with two options in the hoist trunnions for attaching hoist chains use
both attachment points.
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Hoisting – The term used when raising
the bucket
Hoisting is the term used when the operator moves the bucket. There
is hoisting in or hoisting out depending on which direction the bucket
is travelling in. It is controlled via the right hand lever in the operating
position.
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Hose Reels – A device that houses an air
hose
A hose reel is a device that retracts the compressed air hose as part of a
good housekeeping regime.
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Housekeeping – Keeping a work area neat
and tidy
Housekeeping is the generic term used for keeping the dragline area
neat and tidy to ensure it is as safe a place to work as possible.
Housekeeping inside the dragline involves keeping the floor and
walking areas of the machine free from oil and dust, trip objects, waste
materials, etc.
Housekeeping outside the dragline involves keeping the ground work
safe to walk and work on as well cable laid out correctly and marked
with witches’ hats.
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IBS Ropes – Intermediate Boom
Suspension Ropes.
The IBS Ropes support the boom at various points to minimise boom
flexing. Some machines have 1 and some have 2 pairs of IBS ropes for
support.
These ropes are positioned and tensioned to minimise boom flexing
during operation. These ropes should always be equally tensioned.
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Idle Time – A stoppage when the operator
fails to enter a delay into the monitor
Idle time is usually a failure on the part of the operator to enter a delay
into the production monitor. Not all monitors call it idle; some may
call it stand-by or some form of unknown delay. There should never be
idle time for a dragline as there is always a reason for a delay, and the
operator should ensure there is a delay entered.
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In Situ Density/SG
Latin. “In its original place; unmoved unexcavated; remaining at the
site or in the subsurface”.
In mining the in situ SG is derived from drilling results. In
situ SG is typically in the range 1.95 t/CuM to 2.45 t/CuM
although can be over 3 t/CuM in iron ore mines
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In-House Phone System – A
communication system within a dragline
The in-house phone is a communication system built in to the dragline
with terminals located in strategic places in and outside the dragline as
well as the boom and mast.
Although these systems on draglines may be made by different
manufacturers, they are all used for communication purposes.
A Typical In-House Communication System Terminal
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Inline Air Filter – A filter fitted into an air
line
Inline air filters are usually fitted just before the termination point. A
typical termination point is before the air enters the individual motor
braking system. The filters are used to filter condensation from the
compressed air before it enters the terminal points.
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Innovation – Developing New Ideas
Innovation is the implementation of new ideas. New ideas may be
something as simple as just doing a particular fill differently to the
previous one. In the last decade or so, there has been major innovation
in many aspects of dragline operations. Pit design and dig
configuration has changed dramatically as pits have become deeper.
Innovation in all aspects of dragline operations will continue to be
developed to meet demand in the future.
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Inside Bend - A non-straight strip
An inside bend is where a strip bends towards the lowwall side. This is
not a desirable way to set up a pit and should be eliminated from strip
plans as quickly as possible. The main problem with an inside bend is
the reduced volume of space available to put the spoil.
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Inside Key – A trench that the dragline
digs while sitting on the outer edge of the
bench
An inside key is one not dug against the highwall. It leaves a small
amount of spoil on the highwall (the trim) which should be dug later in
the excavation sequence. The dragline sits on the outer edge of the
bench, and excavates the trench (inside key) in the block to build an
in-pit bench/bridge. Mostly used in conjunction with a key/bridge
method, but can also be used in the extended key method to widen the
low wall bench for the dragline to sit while digging the low wall block
High
Wall
Trim
Inside
Key
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Insulator – Power barrier
An insulator is placed as a barrier between the power supply and the
structure holding the power lines
Insulators
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Intermediate Sheaves – The sheaves part
way up the boom that carry the hoist
ropes.
Intermediate Sheaves carry and guide the hoist ropes from the house
to boom point. Some machines have 1 set and others have 2 sets of
intermediate sheaves. These sheaves also help to stop the hoist ropes
from making contact with the top of the boom lacings (due to the curve
/ catenary from the weight of the steel wire rope) and so minimise
damage. These sheaves usually have guide rollers above them so that
the ropes don’t jump out of the groove.
Intermediate
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Isolation Lockout – A system to positively
remove power from the functions
An isolation lockout is a safety device to prevent unauthorised
movement of the dragline functions while the machine is under repair
or maintenance conditions.
There are many methods of isolation and the photos are an example of
one of these.
The first figure shows the Excitation Isolator locked. The key to the
lock is put into the box shown in the second figure. Personnel
working on the machine use their locks to complete the process. In
this case excitation cannot commence until all locks are removed.
All mines should have a Safety Management plan and process for
Positive Isolation under the existing legislation.
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Jarring the Ropes – Shock loads passed
through the ropes
Jarring the ropes causes shock waves through the ropes and back to
the whole drive train. This will occur in both the hoist and drag and is
usually the result of poor operating skills. Jarring occurs when a rope
is allowed to go slack and then experiences rapid uptake of load. A
good example is when an operator pays out the drag before
disengaging. If the drag ropes are slack and the bucket disengages
from the bank the pendulum effect of the bucket will severely jar the
drag system.
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Jewellery - Another name for the rigging
The jewellery is a term used to describe the rigging and includes hoist,
drag and dump chains. It encompasses all rigging between the bucket
and drag and hoist ropes, and excludes the bucket.
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Key Cut – The initial trench dug into
the overburden
A key cut is usually the first trench excavated into the overburden
block. Depending on the dig method, this trench can be positioned in a
few places. There are high wall keys in key/bridge and extended key
methods. A low wall key during a box cut operation, and inside key in
key/bridge and extended key methods also.
Extended Key
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King Post (King Pin) – A shaft protruding
from the centre of the tub
The King Post is a shaft attached to the tub which inserts into the main
chassis of the dragline, (the revolving frame), to allow the machine to
rotate and keep it aligned on the roller path and tub.
The power cable to the working machinery in the house come through
slip rings attached to the king post.
The King Post is also called the Centre Pintle.
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KPI – Key Performance Indicators
KPI’s are used to measure the performance of a dragline or an
operator.
Some of the KPI’s used to measure performance are cycle time, dig
time, fill time, swing time, swing angle, return time, spot time,
payload, dig rate, to name a few.
These KPI’s give the operator or the mine a measure of how they are
tracking against pre-set targets.
KPI variation against Previous Period
Variation (%)
40
30
22.5
20.1
20
10
8.6
2
0.6
0.2
7.6
1.9
0
-10
-20
-0.8
-10.5
-12.2
-30
-40
Reporting period
One of the PwC graphs that are a measure of performance.
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Lacings – The structures that join the
chords
The lacings in the boom are a critical component of the structure as
they give the boom strength and stability. It is important that a mine
has a regular inspection routine to constantly check
boom integrity.
Lacings
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Lag – The time / distance the bucket is
behind the dragline when swinging
Inertia is the tendency of a body to resist acceleration; the tendency of
a body at rest to remain at rest. When swing motion is applied, inertia
causes the bucket to stay at rest until the force of the moving boom is
greater than the inertial force encouraging it to stay at rest. The result
of this is the bucket is behind the swinging boom. It is often called lag.
Lagging of the bucket increases damage in the boom therefore ideal
operating performance keeps the bucket under the boom as much of
the time as possible.
Also there is lag when changing hoist and drag motor direction. This is
one of the reasons that lever jockeying is such a bad practice as the
motor lag doesn’t allow the motors to move in one direction before the
lever is moved to the opposite direction.
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Lay – The rope grooves in the hoist and
drag drums
The lays on the drums are designed to position the ropes neatly on the
drums.
Through poor operating practices the ropes can jump a groove and get
damaged. Regular checks by the crew will contain and minimise
damage to the ropes.
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Leadership – The people at the top and the
way they act
There is clear evidence that mine performance varies considerably;
even between similar sites with the same equipment. The current state
of knowledge across a range of industries indicates that leadership,
management, and group culture determines a significant proportion of
variability in productivity between sites. The people at the top and the
way they act have a very big impact on how other people perform their
duties and the overall functioning of the mine. We believes the best
approach to leadership is based on the Full Range Leadership Model,
proposed by Bass and Avolio.
Extensive research on organisational and group behaviour reported in
high impact journals suggests that between 30% and 40% of all
organisational and group behaviour can likely be attributed to
leadership. Consequently, it is clear that mine leadership has a high
impact on local mine culture and work practices.
Positive mine site culture is usually driven from the top down; through
transformational leadership at all levels of management. Management
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personnel should be trained (there may be some born leaders, but
effective leadership skills can be trained) in transformational
leadership skills and should demonstrate the following;
1.
The ability to build trust from the mine personnel

Leaders instill pride in others

They act in the best interests of the group

Operator personnel respect them

They display power and confidence
2.
Act with integrity

Demonstrate important values and beliefs

Demonstrate a strong sense of purpose

Strong moral and ethical approach

Develop a collective sense of mission
3.
Build confidence and enthusiasm

Act optimistically

Act enthusiastically

Communicate a vision for the future

Express confidence in mine personnel
4.
Encourage innovative thinking

Continually reassess operating assumptions

Seek different perspectives

Listen to other people

Offer ideas on new ways of operating
5.
Build and coach other people

Commit time to teaching and coaching

Treat everyone as individuals.

Help others develop their strengths
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Specific actions for mine leaders include;
a) Take an active interest in the operation

Visit the equipment regularly and talk to the operators

Receive meaningful reports

Spend time every week pondering about the operation and
developing ideas for improvement

Take an active interest in the activities of the Business
Improvement Group

Understand the value of equipment productivity to the site

Hold people accountable for achieving reasonable targets
b) Leaders should provide sufficient budget for value-adding in
the mining process.

Cutting costs is not something which can be done in isolation
to a determination of the real value actions may provide.
Mine leaders should support an influential and empowered Business
Improvement (BI) group. This group (and their leaders) should have a
high level of authority, and be responsible and accountable for
improvement in the mining fleet operation.
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Legra – A high wall pit de-watering pump
Legra is a brand name that manufactures high wall pit dewatering
pumps. They are used extensively to remove a built up of mine water
from the pit in front of the dragline as well as other pit water removal
activities.
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Leica –Dragline monitor
Leica Geosystems produce a complex dragline monitoring system. It
was previously called Tritronics and is currently marketed as being
Series 3.
The Series 3 Dragline Monitor provides instant feedback on a range of
dragline performance measures including cycle times, production
rates, and the current weight of the bucket. It also provides the
opportunity to gain quantitative feedback on future initiatives.
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Lever Jockeying – Excess movement of the
control levers
Lever jockeying is a term used for excessive lever or pedal movement,
or pumping the levers. That is maximum movement in one direction
followed by a rapid switch to the opposite direction. Motor lag means
that excessive pumping of the levers does not allow the motors to
rotate in either direction and can cause burning to the motors and MG
sets.
Lever and pedal jockeying is a bad practice for an operator and should
be eliminated.
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Lighting Control Panel – Switch Board for
the Dragline Lights
The Lighting Control Panel is the central switch board to control the
lights on the dragline.
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Lighting Plant – Mobile pit lighting
A lighting plant is used around the dragline to light the area when
machinery is operated outside the lights of the dragline.
They are used extensively in the pits.
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Lip – The cast section of the bucket nose
The lip is made of cast metal and then welded onto the front ring of the
bucket.
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Low Wall – Spoil side wall of the
excavation
The low wall is the side of the pit where the dug spoil has been placed.
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Low Wall Bench – The area between the
low wall crest and the toe of spoil
The low wall bench is the area between the crest of the low wall and the
toe of the spoil heaps. Depending on low wall and spoil stability, the
bench width can vary from nothing to a distance advised by the mine
geologist.
Low Wall
Benchh
Most operations have around 5-10 metres of bench to contain and stop
rocks falling into the pit. A bench on the low wall allows access for pit
lighting plants and easier access for OCE Inspections. When spoil
room is at a premium and stability isn’t an issue, some operations will
not worry about having a low
wall bench.
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Low Wall Block – The low wall side of the
dig area
The low wall block is the area left after the removal of the high wall
key, extended keys and/or inside keys. The low wall block can be
recognised as being when the dragline sits on the low wall side to dig.
The spoil normally goes directly to spoil. The size of the low wall block
is normally maximised as it is easier digging than the key.
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Low Wall Key – A trench dug into the
overburden near the low wall batter
The low wall key is a trench excavated along the low wall batter. This
technique is mainly used when excavating a box cut or when the pit
advances to the end wall.
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Low Wall Ramp – An access ramp on the
low wall side of the Pit
A low wall ramp is the access for vehicles and equipment to the coal
seam cut by the dragline (and other equipment) every time the
dragline digs a strip. They are often parallel to the strip and are used
to reduce the impact of the void created by perpendicular ramps. They
will often come out at the end of the strip where digging starts. This is
done to provide coal access as soon as possible after the dragline starts
a strip.
Preparing the
Low Wall Ramp
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Lox Line – The line where the coal is
considered of sufficient quality to mine
profitably
LOX Line is the Line of Oxidation. During mine exploration many test
holes are drilled to find the location of the LOX line, where enough
non-oxidised coal exists to make the strip economical. The low wall toe
of the box cut is excavated along this line. As the lox line is never
straight, the initial box cut may have bends in it. The second strip is
usually one or more trim cuts to straighten the pit.
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Lube Drums/Tanks – Bulk storage of
lubrication medium
On a dragline the lubrication is automatically operated and is fed from
bulk tanks and drums. There are a number of lube grades used, and
there is a tank for each grade.
Lube
Tanks
Lube
Drums
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Lube Injectors – The lube metering
applicators
The lube injectors are adjustable metering devices for measuring the
required quantity of lubricating material applied to each bearing.
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Lube Panel – The lube panel controls the
lubrication application
The lube panel controls the required application of lubrication to the
various bearings in the drive trains of the dragline through the lube
pumps.
Lube Panels
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Lube Pump – High Pressure Lube Pumps
The Lube Pumps, controlled by the lube panels, push the lubrication to
the various lubrication injectors throughout the dragline.
Lube Pumps
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Lube Room – The room that houses the
lube pumps / tanks
The bulk lube tanks are housed in a room separate to the rest of the
machinery house
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Lube System Distribution Board –
Distributes oil
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Machinery House (Dragline House) – The
House Contains all the Working
Machinery
The dragline has a machinery house that covers all the machinery to
keep the weather out.
The house is pressurised to keep the dust out of the operating electrical
components as well as keeping the machinery cool in hot weather.
Machinery
House
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Main Chords – The main chassis of the
boom
The main chords in a dragline boom are the chassis of the boom. On
Marion and P & H draglines, there are 4 main chords and a BE
dragline has 3 chords.
Main Boom
Chords
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Maintenance – Managing delays
Best practice draglines have a focus on keeping swinging. As a subset
of this, when something breaks they have replacement parts available
and sufficient trained people available to do the work and a focus on
having the dragline stopped for as short a time as possible.
Best practice for different makes and models in annual planned and
annual unplanned maintenance is shown in the table below.
Dragline
Planned
Maintenance
(hours)
Unplanned
Maintenance
(hours)
Availability (%)
BE1300W/1350W
239
539
91.1%
BE 1370W
335
880
86.1%
BE 1570W
320
444
91.3%
BE2570W/2570WS
189
579
91.2%
Marion 8050
305
571
90.0%
Marion 8200
163
856
88.4%
Marion 8750/8200S
116
536
92.6%
P&H 9020
511
906
83.8%
Data accessed from PwC Databank. Current until 31 December 2013.
There are a number of draglines (independent of age) which achieve
90+% availability (operating time/scheduled time) and this provides a
useful target. Figure below contains a random selection of draglines
from the databank. If the dragline is scheduled to work the full year on
7 day roster the planned plus unplanned maintenance hour target
should be 900 hours. Every dragline is capable of achieving this
number. However, it doesn’t just happen. It requires planning and
effective execution. Every hour stopped above this represents money
being lost.
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Dragline Availability vs Age
Having the dragline operating is the primary way the mine makes
money. Consequently the mine requires a maintenance department
which is dedicated to keeping the dragline operating. They have the
following characteristics;

Reliability of parts is logged and replacements acquired before
required

Sufficient/excess labour

Labour personnel are trained

Labour personnel understand why it is important for the dragline
to be running

Stoppage events are studied to ensure future stoppages are
shortened
As in all aspects of the dragline the performance should be recorded
and presented to the appropriate people in a meaningful way to enable
value-adding change to be made. This issue requires significant
support from executive management to provide sufficient (and maybe
excess by some definitions) labour to be able to respond quickly and
intelligently to breakdown events. This might mean higher
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maintenance labour costs but in most cases this will translate into
higher availability and more coal uncovered with higher incremental
margin.
The provision of parts is a key to the process of minimising
maintenance stoppages. Key aspects of this are;

Longer term long lead time parts requirements may be covered
through participation in a Parts Pool organization, arrangements
with suppliers for access to these parts or simply carrying them in
inventory.

Spares availability should be monitored on a daily basis by the
mining and maintenance personnel and communication channels
maintained between them.

Replacement parts and tools should be readily accessible i.e. a full
set of tips, adaptors and bolting items located close to the dragline.

Operations crews should participate in replacement of these spares
and should be trained in the replacement procedure.
Many mines fall into the trap of seeing the maintenance department as
a cost centre rather than a value-adding centre. Maintenance
departments (which clearly should have a budget like every other
department) add value through delivering equipment with higher
availability. All maintenance related activities need to be controlled to
minimise the negative impact (delays and interruption) on the
operation.
Best practice operations understand the value-adding proposition of
improved availability and support the maintenance department to
deliver that value.
This is achieved in the following methods:




Reducing overall downtime. Downtime costs production (which
makes money) as the mining equipment cannot produce.
Realistic estimates of planned maintenance activities should be
provided to allow for optimal production planning and execution.
Through consistent communication and feedback to operations
about what is needed, why it has to occur and how long tasks are
going to take. Supervisors can make decisions, plan and control
their logistics if they know what is going on.
Through coordinating maintenance delays with production
activities. Opportune maintenance should be carried out when
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








possible during shift changes, meal / crib breaks, etc. to minimise
the impact on operating time.
Optimum timing of equipment out of the circuit for maintenance.
Equipment should not be taken out of operation until other
equipment has been returned from maintenance.
Equipment should only be taken out of production if there are
sufficient resources to work on it, unless it is a critical
requirement. Resources should be allocated to each task to
complete in the quickest / safest possible time and returned back
to production.
Through the coordination of maintenance delays within
maintenance departments.
Through educating maintenance departments on the relative
value contribution of each piece of equipment to allow them to
prioritise maintenance resources.
Facilitating communication and trust between mine operating
and maintenance departments. The outcome will be enhanced if
they work together and not against each other.
Reduce unplanned / unscheduled (breakdown) maintenance as
this consumes more downtime.
Maintenance teams cannot plan for things they don’t know about
nor work efficiently without an applied inspection and repair
strategy. Operations plans should be known to maintenance
planners.
It is imperative that all machines operating in the system are
operating at their design productive capacity as much as possible.
Monitor maintenance compliance and accuracy on a regular basis.
Availability is not the only measure; total output is a key KPI.
A key characteristic of many dragline operations is the belief in a major
shutdown (50 days or longer) every five years. A study of best practice
draglines shows this is not necessarily required. The figure below
shows dig rate during the eight quarters before and after a major
shutdown. It shows an increase in dig rate over the shutdown.
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Dragline dig rate pre and post major shutdown
However, the primary driver for this increase in dig rate is upgrading
target suspended load and increasing bucket size with the resultant
increase in payload. The plot of availability before and after a major
shutdown tells a different story.
Dragline availability pre and post major shutdown
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Apart from a jump up immediately before the shutdown, logically due
to maintenance being delayed due to the impending shutdown, there is
reasonable consistency before and after the shutdown.
However, best practice draglines don’t always have long shutdowns.
Figure below is a plot of the availability of draglines which have
worked a minimum of eight years without a stoppage of 50 days or
longer. It shows an average availability consistent around 84% with a
very slight fall; but most importantly, there is no point where the
availability drops dramatically.
The clear message is, “Don’t plan on stopping draglines for extended
periods.” Unless there is a clear mandate to replace failing or worn out
elements.
Dragline availability for machines not stopped for 50 consecutive
days or more in eight years
For the best practice draglines the machine is stopped only when it
needs to be stopped for as little time as possible. Following the
philosophy of keeping it going for as long as possible between
stoppages.
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Maintenance Logger – A Machine that
Measures the Stresses Associated with the
Machine Operation
A Maintenance logger measures the stresses in the areas that have
been fitted with strain gauges. The boom, mast and A frame are the
most common areas fitted with strain gauges.
Machine operations and the operator are the main contributors to a
damage event and it is important that there is feedback to the operator
in a timely fashion.
The logger is a tool that lets the mine know when there has been a
significant damage event so that it can be checked out before a
catastrophic failure occurs.
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MAL (GAL) – Maximum Allowable Load
Maximum Allowable Load is a number (normally used by suppliers)
which specifies the load which no individual loads should exceed.
Has generally not been used or followed by the mines as the suppliers
generally underestimated what peak loads the dragline may achieve.
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Marion – A Dragline Manufacturer
Marion is one of the manufacturers of draglines and other
earthmoving equipment.
Taken over by Bucyrus who are now owned by Caterpillar, they made a
range of models from small machines to large.
Mast – The Mast is Situated between the
Boom and A – Frame
The mast is the structure that is situated between the boom and
gantry/A frame, and has the main suspension ropes attached to it and
rope or steel support attached to the gantry/A frame. The structure is
made up in the same way as the boom, with main chords and lacings.
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Mast
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Mast Foot – The lower end of the mast that
attaches to the revolving frame
The mast foot attaches the mast to the main chassis of the dragline, the
revolving frame.
Mast Foot
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Mechanical Delay – A stoppage associated
with a breakdown or repair of the
dragline
A mechanical delay is the time spent not operating due to waiting,
repairing or inspecting a problem of a mechanical nature. It could be
associated with the bucket or any mechanical issue arising around the
machine.
A discrepancy often arises between time the maintenance department
attributes to a mechanical delay and the time the mining department
(via the monitor) attributes to it.
To gain maximum value from a mine’s analytics the maintenance and
mining departments must agree on how time is allocated and make
sure they report the same numbers.
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MG Sets – Motor Generator sets
The MG sets generate the DC voltage to drive the hoist, swing, drag,
and propel motors. The MG sets are driven by 2 AC Synchronous
motors. There are banks of MG sets and the number of sets
corresponds to the number of motors in the 4 functions.
The BE machine pictured, has 2 banks of MG sets, with 12 individual
MG sets.
MG Sets
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Mine Official – A person on a mine site
with legal / statutory responsibilities
A mine official is someone nominated by the registered mine manager
who accepts statuary responsibility.
Most mine officials are in a supervisory or management capacity.
OCE’s (Open Cut Examiners) hold mine official status. The SSE
(Senior Site Executive) is often the Registered Mine Manager. This
person is responsible for compliance with legalities and may be
different to the General Manager or Mine Manager.
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Mine Planning – An engineering function
Mine planning is the generic description of the process from drilling to
actually doing the mining. It is a function of planning ahead for what
the mine needs to do to operate successfully. Most people see the
planning as just the part circled in the figure below but it is much more
than this and incorporates multiple people. Mining plans may include
operating plans or schedules or costs. The planning function is
normally distinguished as short term, medium term or long term.
Traditionally this has been an engineering function but with shortages
of engineers other people have learnt the role. One part of mine
planning is the Dragline Engineer’s role. This role involves liaising
with operations personnel to produce plans which are workable and
meet the needs of operations people.
Estimation of
resources
Geo specific samples
• Sampling
- Geological
- Geometrical
- Metallurgical
• Database Management
• Assaying
• Density
• Verify Results
Geological
Engineering
•
•
•
•
•
•
Laboratory Measurements
Rock Mass Models
Stress Models
Validate
Engineering Assessment
Mentoring Programme
Derive Models
& validate
• Geological Model
• Geological Units
• Varicography
• Validate
Estimation of Resources
• Grads Interpolation
• Tonnage
• Classification
- Measured
- Indicated
- Inferred
• Validate
Exploration Programme
• Sample Collection
• Estimated Cost
• Schedule of Work
Mining Plan
•
•
•
•
•
•
•
•
•
Methods & Layout
Equipment Selection
Extraction Strategy
Mine Service
Operational Supplies
Manpower & Productivity
Cost Estimates
Production Plan
Schedules
Budget &
Evaluation
•
•
•
•
ABC Estimates
Revenue & Penalties
DCF Analysis
Risk Analysis
Mineable
Reserves
Metallurgical
Engineering
•
•
•
•
•
•
•
•
•
•
Metallurgical Test work
Validate
Geometrical Units
•
Numerical Progress Models •
Process Design
•
Operational Supplies
•
Manpower & Productivity •
Cost Estimates
•
Metals Schedules
Impunities Schedules
Proven + Portable
Infrastructure &
Services
Process Plants
Site Utilities
Tailings Disposal
Site Services
Manpower & Productivity
Cost Estimates
•
•
•
•
•
•
•
•
Ownership & Permits
Cut-off Grades
- Resources
- Measured
- Indicated
Inferred
Reconciliation
Grade Control
Environmental
Measurements
Closure Plan
Business Plan
Beniscelli et al (2000)
Good plans are essential. Mining / engineering plans must be timely,
accurate and achievable. The main objective when developing and
reviewing operational plans is to optimise the pit design and dig
methodology to achieve safe removal of the required volume of burden
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(TCM’s, BCM’s, PBCM’s or BCYd’s depending on country), to the
correct location in the shortest possible time and/or the lowest unit
cost. The safe and efficient means of achieving this objective requires
detailed planning and scheduling, and relies on good communication
and co-operation between the Technical Services Department
(Planning), the Operational Superintendent / Manager, supervisors /
frontline leaders, and the crews.
Best practice operators and superintendents along with the frontline
leaders play an important role in the process of achieving business
objectives as their knowledge of the equipment capabilities and their
ability to anticipate and identify / manage problems has a direct
influence on delays, dig times and overall efficiency. Therefore, they
must play an active role in the development of the plan.
The best practice process for achieving timely, accurate and achievable
plans is;
1.
Have an experienced and competent planning engineer and
superintendent, or contract a consultant or consultants to help.
2.
For every pit or bench the engineer and superintendent must
meet to discuss the excavation a minimum of a month ahead of
planned work.


Previous strip or block or bench in the same pit is reviewed
along with other relevant, subsequent issues.
Common understanding of the approach to be employed is
developed.
3.
Engineer develops the draft plans for the pit using 3D (and
maybe 2D as well) planning tools. The plans should include
identification of Dragline or Truck & Loader sequencing in the
pit. Pit, strip, blocks and loader locations must have a unique
identifier. Digging locations are provided in detail.
4.
Meetings are held amongst engineer, superintendent and
operators to discuss the draft plan. Some operations may
include frontline leaders.
5.
Modifications made to plans and final plans issued.
6.
Sign off by engineer, superintendent and operators. Agreement
that plan won’t be changed without specified procedure being
followed.
The minimum required plans are;
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
Strip or bench plan/s (plan view and cross sections) showing
blocks and spoil movement with key information marked.
Plans must include dates planned to be at points down the pit
for reconciliation purposes.

3D plans showing digging sequence.

Block plans showing planned digging and dumping locations.

3D animation of strip / bench excavation on designated
computer.
Typically these plans are discussed at a weekly planning level. This is
where a more detailed and short term view is able to be applied to the
machine performance prediction. At this stage of planning it is
possible to predict when and where planned maintenance will occur as
well as any major moves, meetings, or any other planned delays.
Therefore the targeting of planned output and rate is what should be
achieved on a given day or shift for average availability (excluding
planned work) and average utilisation (excluding certain unplanned
delays).
Planned performance may and will vary from shift to shift and day to
day depending on the inputs into the plan. The setting of targets is
about knowing what the potential for each piece of equipment is. This
has an internal and an external focus of what the same make and
model achieved in an earlier period of time and what it achieves
elsewhere. This allows capacity modelling for the piece of equipment
and the system as a whole. Typically the rate for the loading tool is
calculated from optimal cycle time and spot time. Assumptions are
made about availability that do not include significant downtime
events. Utilisation inputs are typically set at benchmark performance
although considerable care must be taken in accounting for
constraints.
Not only is a good plan essential, best practice operations hold
operators accountable for following plans and have systems in place to
respond when an operator thinks a plan should be changed. Key
actions are;
1.
Operators’ record digging location and details on their shift
report. Every time the operator changes digging location /
position of machine the change must be identified and
consistent with the approach specified on plans. Alternatively,
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GPS systems can be used to provide a record of the movements
and R.L (Reduced Level) information.
2.
Operators do their very best to follow plans, including, digging
and machine locations. Truck drivers position themselves to fit
in with loader technique. Bench/floor levels may be set using a
hand held or a machine mounted GPS device.
3.
Markers / survey pegs should indicate all key positions in the
pit, e.g. high wall, low-wall, end-walls, and block locations as
well as provide support for locating the loading unit and getting
R.L heights correct.
4.
Superintendent checks pit layout, digging, machine positioning
and recording of operations every shift to ensure compliance
with plan.
5.
Operators are not authorised to change operations away from
plans except for immediate safety issues, e.g. geotechnical
issues, physical blockages, etc.
6.
Any other change in plan must be authorised by the
superintendent and must be agreed to by the operator,
superintendent and engineer.
7.
Where feasible, the engineer must produce revised plans ASAP.
8.
Revised plans must be communicated to all crews.
9.
The engineer and superintendent must visit each machine daily
to discuss any issues with execution of the plan.
Reconciliation of fleet performance is also essential. Ideally it should
be done based on volume moved and advance in the pit. The engineer
must prepare a plan showing the dates when certain points are
reached in the strip or bench. Actual progress is then marked.
Variation from plan can be interpreted via a decision tree as shown in
the following figure.
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Loader decision tree example.
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If the equipment has not achieved the planned volume moved or linear
advance there are only three things which could have caused this;
i.
ii.
iii.
The equipment has underachieved either in payload and/or
number of cycles (these can be broken down further).
The plan wasn’t followed.
The plan was wrong.
Clearly the focus for planning is to establish a good plan, make sure
there is a process in place for ensuring compliance to the plan, and
providing the mining department ongoing equipment performance
data and identifying where and when gaps in performance have
occurred. This will allow precise corrective action.
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Mine Water – Water collected on a mine
site
Water on a mine site comes either from rain or groundwater. Either
way, under most environmental legislations, water generated on a
mine site cannot be released off site but has to be stored on the site.
This is due to contaminants in the water which has come from the coal
or the spoil and is collectively called acid mine drainage where
concentrations of sulphides increase in the rock, coal and water.
Mine water is used to suppress dust onsite, and some water can be
treated to use in the washing of the coal in the CHPP.
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Minescape – Dragline Module (Ventyx)
Ventyx (previously Mincom) MineScape Dragline is a CAD-oriented
dragline modeling product that enables engineers to define and test
dragline excavation methods on real pit models, quickly and
efficiently. The product includes functions to simulate and measure a
wide variety of material movement methods including cast blasting
and production dozing. These functions allow operations in the pit to
be faithfully modelled. Dragline is the best tool for computer-based dig
optimization, allowing engineers to test new excavation quickly against
real data.
Ventyx MineScape Dragline:




Works on real geology as well as on hypothetical,
simplified sections.
Performs dragline design using geology, pit planning,
survey and scheduling data. Accepted excavation
designs (e.g. drill and blast of burden, reclamation of
spoil) are immediately available to other planning staff
and to surveyors for field layout without any need for
transcription or modification.
Has no limit to the level of sophistication or number of
methods that can be defined and saved
for reuse.
Includes an extensive range of output to assist both
dragline engineers and dragline operators to achieve
the design goals.
http://www.ventyx.com/en/enterprise/technical-miningoperations/mine-planning
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Miracle Hitch – The connection between
the dump block and hoist rigging
The miracle hitch is the 3 way connection that joins the dump block,
hoist equaliser and hoist chains. The miracle hitch was first invented
by John W Page as part of his dragline bucket and rigging designs. The
term miracle hitch was originally given by Bucyrus. There are other
manufacturers that have different designs of miracle hitch and
normally use different names.
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Misfire – The explosive in a blast hole that
has failed to detonate
A blast hole misfire is a reportable incident.
When the shot firer checks the area after a blast and finds a suspected
misfire it is reported and then surveyed for future reference. The area
around the suspected misfire is cordoned off and when the dragline is
digging in the area it is done with caution.
Mine management should have a procedure to be followed in the event
of a misfire.
When digging through the misfire zone the explosive is usually flushed
out with water and the primers removed.
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Mobile Crib Hut – Portable building for
eating meals
Mobile crib huts are fully self-contained with all the household
appliances required for personnel to have their meals.
Mobile crib huts are positioned so the hut is close to where the
personal are working instead of having to transport the personal to the
crib hut.
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MRC – Maximal Rated Capacity
Various measures of dragline size/capacity are used in the industry.
These include ‘rated suspended load’, ‘motor capacity’ and ‘bucket
capacity’. Each of these has shortcomings when comparing dragline
results from multiple sites. A new measure has been developed which
overcomes the shortcomings of previous measures and provides a
consistent basis for measuring dragline size. It has been called
‘Maximal Rated Capacity’ (MRC) and has the measurement unit of
tonnes.
MRC = BERP95 * RBC
Where
BERP95 = Bucket Efficiency Ratio
= payloadP95/RBCP95
= payload for the 95th percentile/RBC for the 95 th percentile
RBC = Rated Bucket Capacity
The fleet of buckets used on the Australian dragline fleet can be broken
into three distinct designs, namely; conventional, scoop, and UDD.
Different bucket designs impact the calculation of MRC through
different BERP95. The BERP95 for each class of bucket, based on the
PwC dragline database are as follows.
Bucket Classes
BER95
a. Conventional
b. Hurricane
c. UDD
2.07
2.32
2.09
[Contact PwC for the latest numbers]
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Mud Map – A roughly drawn plan of
action
A mud map is usually referred to as rough plan of action.
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Multiple Pass – Draglines dig more than
one horizon in a strip
A term used when the dragline digs multiple horizons in a single strip.
This may be for one or one or more seams of coal.
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Nodding – When the bucket is disengaged
a significant distance from the drag
fairleads the front of the bucket dips
When the bucket is disengaged outside the sweet spot or the dump
rope is not set at the optimum length the bucket will nod or dip at the
nose and spill a considerable amount of overburden out of the bucket.
The rigging works in such a way so that the drag ropes and hoist ropes
are connected through the dump rope. When the bucket is disengaged
a long distance from the fairleads the distance between these ropes is
low and the tension in the dump rope is low causing the front of the
bucket to remain buried as the hoist ropes lift the rear of the bucket.
The material flows out the front of the bucket until the teeth disengage
and the bucket springs up into a steeper angle. This action results in
less payload carried to spoil.
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Nose – The part of the bucket lip where the
adaptors attach to the bucket
The nose of the bucket is part of the lip and front ring. Most buckets
have a cast lip and the nose is where the adaptor fits.
Bucket
Lip
Nose
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OCE – Open Cut Examiner
The Open Cut Examiner holds a statuary (legal) position on the mine
site and is responsible for the inspections and safety of an open cut
mine.
The OCE has the authority to close an area of the mine should it be
deemed unsafe to operate in.
As long as the mine is open (even on non-operational days) there will
be an OCE on site.
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Offline Extended Key – A long key cut
excavated at an angle to the high wall.
An offline extended key is excavating a long key cut across multiple
blocks on the high wall side of the pit. Instead of sitting on the high
wall line it is dug offline or from a position further out on the bench
(away from the highwall). At some sites the dozer trims the high wall
batter to ensure design angle and a clean (safe) face.
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Offline Key – A key cut dug where
the dragline is not parallel nor
perpendicular to the highwall
An offline key is excavating a key cut on the high wall side of the pit,
but instead of sitting on the high wall line, it is dug from a position
further out on the bench (away from the highwall but not
perpendicular to it. At some sites the dozer trims the high wall batter
to ensure design angle and a clean (safe) face.
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Oiler – Less experienced dragline operator
The oiler is another name for the second person on the crew. The title
Oiler, stems back to the early 60’s when there was a push for training
operators to meet the demand for mine expansion. The oiler is
responsible for relieving the operator when they are on a break and
uses operating time to gain experience.
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Operating Cost
This is broken down into fixed costs and variable costs.
Fixed costs are the same regardless of what the dragline does and
include access to electricity grid, lease payments, labour, etc.
Variable costs depend on hours operating and/or number of cycles
done.
It is complex and difficult to compare the costs of different draglines.
It is known that a dragline operation is generally a less expensive way
to move spoil compared to a T&L operation and the dragline cost is
around $1.00 /PBCM (This is the cost in operating the machine).
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Operating Delay (Process Delay) – A
dragline stoppage associated with the
operational side of the dragline process
A process (or operating) delay is a stoppage associated with the
operational side of the dragline process. Walking / maneuvering /
positioning around the block, wait on dozer and cable moves are three
of the most common delays. There are many other operational delays.
Many operational delays are under the control of the dragline crews
although waiting on other actions may be outside their control.
Operational delays are associated with utilisation through the generic
formula
Dig time
Utilisation = ---------------------------------Dig time + Operating Delay
Best practice dragline operations keep the dragline swinging
productively and minimise the amount of time stopped.
One of the key operating delays for the dragline is wait on dozer. The
dragline dozer performs a range of tasks around the dragline, some of
which for safety reasons may require the dragline to stop working in
the same area.
The dragline and dozer operators should work together to keep the
dragline digging (productively) for as long as possible. The ‘Best
Practice’ dragline operations have the highest % of Dozer Utilisation.
Best practice draglines often have three person crews and where two
person crews are used will access further labour during the shift to
keep the dozer operating. The following are key aspects to minimising
the time the dragline is stopped while waiting on dozer and
maintaining a safe operating environment.



The dozer should be seen as an integral part of the
dragline operation and should be treated as an area to
report on and improve at all times
The importance of keeping the dragline swinging
should be communicated to the dragline and dozer
operators
The dozer operators should always follow the
standards of the mine.
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A key to the efficient use of dozers around the dragline (keeping the
dragline operating productively) is establishing and maintaining two
digging and/or dumping locations around the block. The next Figure
are showing two pictures how a dragline might have two dig/dump
faces on the one block. In the first the dragline is digging in the key
and dumps behind themselves to fill in the dragline pad. The second
figure shows the
dragline digging
in the block and
dumping
around in the
spoil. This is
only an example
of one option.
There is a
multitude of
ways to set up
dual
digging/dumpin
g faces and the
aim should be to
maintain this
principle at all
times.
Dragline with two dig/dump points.
Further to this the second area of safety risk is at the rear of the house.
Dozers working in the swing arc of the dragline boom (at the rear)
should always make their intentions known and be in constant
communication with the dragline operator. All draglines and dozers
should have proximity sensors fitted so that if the dozer comes too
close to the house an alarm sounds. This proximity should be
established by the mine but as a general rule 25 metres from the centre
line of the dragline is a good distance for keeping the dozer away from
the rotating dragline house.
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Operating Time – The time the dragline
is available to operate
The operating time is the total hours that the dragline is available to
operate in a given time frame and normally equals dig time plus
operating delays.
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Operator – Person who operates the
machine or equipment
Obligations






Do not endanger your or any persons health and safety
Report all unsafe conditions, activities, near misses,
hazards or injuries to your supervisor.
Do not tamper with or deactivate any health and safety
devices or procedures.
Use the appropriate PPE.
Report all damage and or defects.
Do not attempt a task unless qualified, authorised,
competent
and confident.
Roll










Attend all shift briefings, tool box talks and shift
handovers.
Ensure you understand and have all relevant data
available on your planned activities.
Understand/analyse all information/instructions
given and plan
your task.
Use the correct equipment for the job.
Do the required walk around and pre-start/shift
inspections.
Understand and apply the relevant tagging
procedures.
Practice a high standard of housekeeping.
Operate the machine safely and in accordance with the
manufacturer’s instructions.
Assess and apply all site safety, environmental rules
and regulations.
Operate as efficiently and cost effectively as possible.
The person who has been trained and authorised to operate specific
equipment or machines on a mine site. The operator is the senior
person on the crew and normally takes responsibility for the operating
during the shift.
The Oiler may also be given the generic title Operator.
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The optimal input of people / operators to the operation has only two
key aspects; select the right people and then create exceptional skills
through effective training and experience. The linkage of these two
factors plus situational factors and personality impacts are shown in
the figure on the next page.
Selecting the right people to train for equipment operators must
account for differing experience, personality, attitude, and abilities
(what you are born with); and can be summarised under the general
title Human Factors Engineering. Personality and attitude can be
assessed through structured interviews, while experience is
determined through contacting previous employers and quantifying
time / type of equipment operating experience.
The key abilities which correlate to operator performance are hand-eye
coordination and time movement anticipation.
The best practice process of selecting the right people for training has
three aspects;
1.
Structured Interviews (all applicants are asked the same
questions)
2.
Assessment of work history
3.
Abilities testing
Best Practice operations identify, acquire, and recruit operator trainees
with potential for exceptional performance (as identified by measured
abilities - Lumley DBA Thesis, 2007). Some companies choose people
in the top 30% of the population; some choose the top 25% and one
will only choose those in the top 15% to operate its excavating
equipment. The Vienna Test System (Schuhfreid – Austria) is the time
proven preferred measurement tool for quantifying these abilities.
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Conceptual Framework for Operator Performance
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It is desirable for all potential operators to undertake abilities (VTS)
based assessments to assist in identifying their potential performance;
quantifying their safety-related abilities; and identifying opportunities
and recommending tailored training plans to optimise their skill set
based on their underlying abilities.
Undertaking abilities testing is something every mine should consider.
In some jurisdictions there are significant legal and/or union issues
related to pre-employment testing. Abilities testing with VTS comply
with the highest standards of professional validation and
implementation can comply with regulations when performed
properly. It must be understood that the testing required does not just
point to productivity; there is a significant safety element as well. The
correlation previously cited in BP 2 between safety and productivity
(R) is 0.79. This correlation is ranked in academic literature as “very
high”. Van Den Raad (1999) produced the following figure as a
demonstration of the link between productivity and safety on a cattle
farm and meat processing factory. He found the productivity was
impacted by 4% due to a focus on safety. Certainly the same
correlation exists in mining.
The Link between Productivity and Safety on a Cattle Farm and Meat
Processing Factory .
A further correlation is concluded through the work of Lumley (2007)
and Gladwell (2009). Lumley (2007) found that performance had a
strong link to specific measureable abilities. It seems obvious that
selecting the “right” people is the fundamental first step. Given that
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Lumley (2007) developed a method for selecting highly prospective
(on the basis of productivity) people.
To optimize performance for currently operating equipment fleets with
untested operators/drivers a plan can be developed to systematically
reallocate people who have lower abilities with newly trained people
with exceptional abilities (potential), within the frame work of existing
labor agreements and human resource practices. These plans can be
implemented over time and are prudent succession planning activities.
The following figure is an example of a 5 year plan to reallocate
operators (due to targeted retrenchments, natural attrition,
retirement, health issues etc.) with trainees and externally sourced
operators that achieve an 85 PR or higher on abilities testing. This best
practice operation targets operators in the top 15% of the population to
ensure excellence. By following this process, they will achieve an
accumulated ~10% increase over the 5 year period.
5 Year operator program example.
Research has shown that to become a master of a skill, 10,000 hours
experience is required (Gladwell, 2008, “Outliers”). Skills can be
broadly grouped into basic skills (those mechanical actions required to
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operate – competent operation) and advanced skills (those required to
operate in a highly productive manner – proficient operation).
The following figure outlines a strategic approach to the Selecting,
Training and Supporting of operators. The training and skills
development of trainee operators are crucial to the overall
performance even if the trainee has been selected as a potentially high
performing operator. If not trained and coached correctly with a high
level of engagement, the operators will not reach the desired level of
performance. Operator selection, training / development and support
are vital to optimising potential and realising sustainable actual
performance.
Operator improvement strategy
The following figure is an example of gaps identified between actual
and potential performance against the top 30% requirement (70 PR)
(the person either has the productive abilities or not).
Underperformance against potential is the result of poor training
which is demonstrated quite clearly in this figure.
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Gap between potential and actual performance
Best Practice operations determine the gaps between actual
performance (analysis based on actual performance from the monitor
data) and predicted performance (using natural abilities). Operators
identified as having sub optimal performance areas are targeted for
specific training programs to up skill and close the gap. The
measurement of these gaps forms the basis of advanced skill
development.
It is a proven fact that most people learn best through an
interpretation of what is going on in their environment. Mining
equipment operators will interpret what they see and hear; sometimes
subjectively, to determine how they will act in the future. The provision
of meaningful information via regular performance reports and
support in interpreting and responding to those reports helps
operators make sense of their environment and helps them make the
best decisions regarding future actions.
These reports are the single most important ongoing
training and improvement methodology that a mine can
employ. Training should not be viewed as simply classroom
instruction but as an ongoing support and personal progress reporting
system for the operator / driver presented in their key learning
environment.
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Monthly reports allow for sufficient data to be collected to make
outcomes of the KPI’s reported statistically sound. Delayed or belated
support has a reduced influence on an operators’ ability to target key
improvement opportunities. A mine will lose the ability for maximum
impact on sub-optimal performance if this reporting process is
deferred to a quarterly / three month process. A single operator with 2
months of suboptimal action without rectification would cost the mine
many thousands of dollars.
The value of lost productivity is so high, PwC strongly suggest that all
major equipment have a formal reporting and feedback regime.
The process of creating understanding to a point where an operator
feels confident in making changes in operating habits may involve the
input of a well-trained experienced operator to act as a mentor to
connect the content of the reports to operators actions in the
equipment operating environment. Reports, ideally, are delivered
monthly to the operator in person by an external or internal operator /
training expert. Reports will contain performance compared with
previous periods, the machine average, and global best practice for the
period analysed. All report data should be designed to provide
meaningful information upon which to act.
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Extracts from a sample operator report
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Operators Cab – The operator’s control
room
The operator’s cab is the area where the operator sits to operate the
dragline.
It has the control panel with the operating levers and pedals, the
production, duty, and fire monitors to name a few.
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Opportunity Cost
In any economic analysis this is the really important cost


What you really need to understand is what the value
in moving more dirt or the opportunity cost of moving
less is.
If you know this then you can make informed
decisions on certain actions.
In any simple economic analysis follow the 3 step approach:



Where draglines are involved convert all dragline
material moved to prime
Calculate additional material that will be moved.
Calculate the cost/value of moving that material
Use one of the following 3 methods
Two cost models (with T&L all have various subsets)

–
–
–
–
Mine is constrained in what it does through coal sales or pit
layout, etc.
No other prestrip or ancillary equipment to shut down first
Is usually used when considering moving fleets faster and/or
reducing scheduled time to operate, e.g. 7 day to 6 or 5
Difficult to quantify accurately

–
–
–
Direct cost savings
Incremental profit on coal available to be sold
Mine can sell all coal produced
Additional coal usually has high profit margin.
How will you bank the gains
Need to know what incremental profit is
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Optimum Bucket Capacity (Formula)
OC
=
(TSL – RW - BUFW)
(BER + BUVW)
where
OC
-
Optimum Capacity (m 3)
TSL
-
Target Suspended Load (t)
RW
-
Rigging Weight (t)
BUFW BER
BUVW-
-
Bucket Unit Fixed Weight (t)
Bucket Efficiency Ratio (t/m 3)
Weight of 1 m3 change in Bucket Capacity (t/m 3)
{ Total Bucket Weight = BTFW + BUVW * OC }
{ Payload = BER * OC }
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Over Swinging – Swinging past the dump
zone
Although the operator has to swing and dump the overburden
according to the dig plan, over swinging (swinging past the correct
dump location) decreases productivity. It is very important for an
operator to hone his/her operating skills so the bucket is always
dumped in the correct position and degree of swing.
It is worth considering that operating a dragline is a skill whereby peak
performance is not achieved until the third year after starting full time
operating. It is a difficult task to master and “failures” do occur.
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Overburden – All material removed above
the coal seam.
Overburden is the waste material above the coal seam. The depth of
the overburden removed will vary according to the strip ratio and the
viability of the coal under it.
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Over-Drag –The operator continues to
drag the bucket after it is full
Most operators tend to over-drag the bucket. Correct machine
positioning, correct dump rope length, and operator skills will
minimise over-dragging.
Filling the bucket is vitally important to gaining productivity, and
operator needs to recognise a full bucket and disengage without over
dragging.
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Overhand Chop – When the dragline is
digging a block of spoil against a batter
with bucket pulling down under its own
weight
When the dragline has to dig overburden against a batter, above the
level of the bench the machine is sitting on, with the bucket filling in a
downward motion under its own weight, it is classed as overhand
chop.
Digging above the tub is usually less productive than below the tub and
less productive again if it is a chop.
The operator will normally pull material into a roll in the front of the
face being dug. The bucket is then engaged behind this roll and pulled
into it to increase the efficiency of filling.
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Overhand Dig – When the dragline is
digging an open face above the tub level
Overhand digging is when the dragline digs an open face block that is
above the level of the bench the dragline is sitting on. This can include
moving a pile of material that has been dumped on the bench surface.
For this situation, the code entered into the monitor would be
rehandle, but it is still overhand digging.
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Overhand Reverse Digging – Nonpreferred method of digging
We probably don’t need to make any comment about this except to be
very careful when the bench is wet as there are substantial inertial
forces applied when the dragline swings and the dragline can slide.
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Overhead Cranes – Cranes mounted inside
the machinery house
All draglines usually have at least 2 or 3 overhead cranes mounted
inside the house, used to cover different areas. These cranes are used
to lift components during repair and replacement. The crane rail
extends outside the house to allow the cranes to load components onto
and off trucks.
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Overload
Overload is how far over the RSL (Rated Suspended Load) a mine is
prepared to run the average actual suspended load. It is normally
expressed as a percentage of the RSL over 100%. Overload is normally
between 0% and 25%.
More recently mines are specifying overload as the percentage above
target suspended load (which may already be above the they are
averaging
Generally, overloading is not recommended by the dragline suppliers
and they will threaten to void warranties if a mine knowingly does this.
Many mines with older draglines accept the risk and will get 3rd party
structural evaluations of the dragline to determine what the safe load
for the dragline is and/or what needs to be done to operate at a
predefined average overload, e.g. 25%. In Australia some mines are
considering the next round of suspended load upgrades to 35%
overload.
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Oxidised Coal – Coal that has been
Exposed to Weathering
Oxidised coal is coal that has been exposed to the air or weathering
over a period of time, and has lost some or all of its heating qualities.
It occurs insitu and would have been subject to air getting to it over an
extended time. Coal can be subject to oxidisation if it is mined and
dumped into a loose stockpile for a period of time.
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P & H – Pawling and Harnischfeger
In 1914 Harnischfeger Corporation, (established as P&H Mining in
1884 by Alonzo Pawling and Henry Harnischfeger), introduced the
world’s first gasoline engine-powered dragline.
See Page for the evolution of the current P&H draglines.
In 1988 Page Company was acquired by the Harnischfeger Co., makers
of the P&H line of shovels, draglines, and cranes.
http://en.wikipedia.org/wiki/Dragline_excavator
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Pad – What the dragline sits on
A pad is the generic term for what the dragline sits on whether in the
pit or out of the pit when not walking. Often used to describe where
the dragline sits for maintenance.
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Page – Early Manufacturer of Draglines,
Shovels and Cranes
The dragline was invented in 1904 by John W. Page of Page Schnable
Contracting for use digging the Chicago canal. In 1912 the company
became the Page Engineering Company, and a walking mechanism
was developed a few years later, providing draglines with mobility.
Page also invented the arched dragline bucket; a design still commonly
used today by draglines from many other manufacturers, and in the
1960s pioneered an archless bucket design. Page also invented the
rigging arrangement for use with their bucket. The basic rigging
design is still in use today.
http://en.wikipedia.org/wiki/Dragline_excavator
In 1988 Page was acquired by the Harnischfeger Co., makers of the
P&H line of shovels, draglines, and cranes.
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Parting – The waste material between two
seams of coal.
Some pits mine multiple seams of coal. The material from the surface
to the first seam is the overburden. Where there are two seams of coal
the material between is called interburden. Where a single seam has
split into two or more distinct seams the spoil between them is called
parting.
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Parts Boat – Sled for carrying spare
rigging parts
A parts boat is a sled dedicated to carrying a selection of rigging parts,
teeth and adaptors and various other items.
Having spare parts close to the dragline reduces the down time during
a break down.
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Payload – The material the bucket carries
and dumps on the spoil.
The waste material that the dragline digs and dumps to spoil is the
payload. The payload is measured by the production monitoring
systems by subtracting the weight of the bucket and rigging from the
measured total suspended load.
The weight of payload can be converted to a volume by dividing by the
in-situ SG.
To maximise payload without increasing the total suspended load,
buckets are being designed lighter and therefore of larger capacity.
Instead of carrying steel they are carrying a greater payload.
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Payload Optimisation – Increasing the
amount of material to the dragline loading
limitation.
Payload is the most important KPI in optimising the dragline
operation. Best practice draglines achieve higher payloads.
The following table shows the payload achieved by the best practice
draglines for each make and model.
Dragline
Best Practice
Draglines’ RSL
(metric tonnes)
Best Practice
Draglines’
Payload
(metric tonnes)
Best Practice
Draglines’
Payload/RSL
BE 1260W
73.0
51.7
0.708
BE1300W/1350W
81.8
63.4
0.775
BE 1360W
102.3
72.3
0.707
BE 1370W
134.5
107.0
0.795
BE 1570W
159.1
116.8
0.734
BE2570W/2570WS
260.8
179.1
0.687
Marion 8050
132.7
100.1
0.754
Marion 8200
170.5
130.6
0.766
Marion
8750/8200S
215.4
147.4
0.684
P&H 9020
218.2
150.2
0.688
Data accessed from PwC Database and valid until 31 December 2014.
If a particular dragline has a different RSL to those noted then simply
multiply the specific RSL by the payload/RSL factor for the make and
model to determine the target payload. Note that payload/RSL is unit
less.
There are many factors that impact on payload but the starting point
for optimising payload is to set a general target as follows:
Min. Target Payload (tonnes) = 2 x Rated Capacity of the
Bucket (cu m)
i.e. for a bucket with Rated Capacity = 47 m3, the target Payload = 94 t
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For those who use imperial units the target is;
Min. Target Payload (BCY) = 1 x Rated Capacity of the Bucket
(CuY)
Every single operator should be instructed to target this payload.
Some will underachieve but most will over achieve (if you set it as a
target). If you set the target as 2 * capacity then the average will come
out at around 2.1 times bucket capacity and best practice draglines
average 2.07 * bucket rated capacity.
As pointed out many mines and operators do better than this. It is
important to note that many contributing factors will make individual
bucket loads less than this target. It is important to continually check
performance to determine if more effort needs to be made or if aspects
of the operation need to be discussed with the supervisor. Figure 1
shows a selection of draglines and their respective BER’s. BER is
bucket efficiency ratio and equals payload divided by rated capacity.
Classes of draglines are shown by the lines. The line running across is
the best fit of the average of each class. It shows that there are a
significant number of draglines which achieve the target BER of 2.
BER vs Total Suspended Load
Best practice equipment usually has a statistically normal distribution
of payload. The amount of negative (or left) skew is a primary
indicator of underperformance. In statistics theory, skewness is a
measure of the asymmetry of a data set. Skewness can be positive or
negative. A negative skew indicates that the tail on the left side of the
distribution curve is longer than the right side.
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A value of skewness statistic divided by standard error of skew should
be (a standard measure of skewness provided by Tabachnick and Fidell
(1996)) less than 3.30 for the normality of the payload distribution to
be acceptable. To comprehend this statement a background in
statistical theory is helpful.
Figure 2 illustrates payload frequency with negative skew, (too high
occurrence in the yellow shaded area). The elimination of the negative
skew is one desired outcome of focusing on payload.
Sample Payload Distribution from a Dragline Report
A second outcome of focusing on payload is how high the peak of the
frequency histogram is. The higher the peak (which provides lower
standard deviation/variability) the better the performance.
The procedure for achieving best practice payload is to communicate
the requirement/goal to all team members, support the operators as
they describe what they need to accomplish this, report individual
performance and group performance, and then eliminate the factors
which are reducing the operators’ ability to achieve best practice
payload on average. Some of the issues which need to be analysed and
reported as part of the dragline performance reporting regime are;

–
–
–
Blasting should provide a well fragmented & loosened spoil.
Measure and report diggability (payload/energy to fill).
Develop a blast model for the site.

–
–
Geology and Blasting
Drag Motor Performance
Poor drag motor performance translates to difficulties in filling & reduced
payloads.
Motor performance should be logged periodically to ensure no reduction.

Engage Location
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–
–
Some areas are more difficult to engage than others.
Analyse and report performance vs engage location.

–
–
Maximise disengaging in the “sweet spot”.
Analyse and report performance vs disengage location.

–
–
Bucket Characteristics
Different buckets will achieve different payloads.
Buckets’ performance changes over their life.
Analyse bucket performance and develop a bucket strategy.
Report bucket performance periodically.

–
–
Operator
The operator’s actions will have the greatest impact on payload – filling
technique.
Report Specific Dragline Output (normalises for bucket, machine make and
model, pit geometry and diggability).

–
–
–
–
Disengage Location
Rigging Characteristics
It is essential that the rigging performance matches the digging technique.
Report rigging to digging periodically.
It is important to continually check performance to determine if more
effort needs to be made or if aspects of the operation need to be
discussed with the supervisor.
The support staff/analyst should prepare and update a plot of average
daily payload, each day. A result more than three standard deviations
above or below the 50 day moving average should be investigated with
an action plan established. Three consecutive days with payload more
than one standard deviation above or below the 50 day moving average
or a three day trend down should be investigated with an action plan
established. The reasons for the deviations should be thoroughly
understood so appropriate actions can be taken i.e. to continue acting
to achieve the above past average performance or to stop actions which
achieved below past average performance.
The key to any improvement activity is to measure the gap and do
something about it which is what the previous guidance is all about.
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Payout – Moving the bucket away from
the dragline.
Paying out the drag is moving the bucket away from the dragline. The
drag is paid out when taking a bucket of material and dumping to
spoil.
Paying out the hoist is lowering the bucket. In both drag and hoist this
is done by pushing the left and right control respectively away from the
operator.
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Pegasys – Dragline Monitor (Mineware)
Pegasys is a unique asset management solution combining
sophisticated electrical and software technologies.
It supports a real time remote operations framework, allowing for
significant aspects of the dragline operation to be monitored remotely.
This offers immediate access to real-time and historical data including:




Production information
Machine location
Vision systems
Structural and electrical feedbacks
http://www.mineware.com.au/pegasysdraglinemonitoring.php
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Pegging – Marking an area
Pegging an area is good practice for a dragline operation. Some areas
are pegged by the surveyor. These may include the pit limits, high wall,
low wall crests, high and low wall toes, the coal edge and if on a bench,
the bench crest and toe lines.
There are a number of areas that should be pegged by the dragline
crew. The block and pull up line pegs, pegs for positioning the dragline
to name a few.
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Pendulum Effect –When the boom stops
swinging and the bucket continues the
motion
When swinging, the bucket’s inertia causes it to lag behind the boom
when the swing begins and to keep moving past the boom when the
swing ends. This movement is called the pendulum effect, which
places adverse loads on the boom. Therefore, control of smooth
starting and stopping accelerations during any swing motion should be
mastered to reduce this effect. Hand-eye-foot coordination is at its
most demanding during swinging-paying-hoisting actions. Most
experienced operators develop the skill to minimise this effect. A
trainee may realise this effect while learning, but with skill will learn to
control it. The effect can happen when experiencing a power outage
while swing is in motion, and the operator has no control over it.
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Pins – A component for joining rigging
There is an assortment of pin sizes used in a dragline’s rigging.
There is also a selection of keeper pins that are used to hold the pins in
place during operation.
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Pit Pump – A dewatering pump used in the
mine
A Pit Pump is used to dewater the pits when the water level interferes
with mining operations.
There are a number of pump manufacturers, with different pump and
engine specification, and the mine needs to choose the right pump for
their requirements.
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Pit Ramp – Roadway to access the pit
Access to the bottom of the pit and the coal seam is gained by the pit
ramp. The ramp is usually dug by the dragline when opening up the
new pit area. Ramp grade and width is governed by the size of the
trucks being used to haul the coal.
The grade is usually a maximum of 8% but can be up to 10%. The
width will vary as the regulations say that “all roadways should be 3.5
times the width of the largest vehicle using it”.
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Plugging – When the swing motors are
reversed to slow or stop the swing motion
During the swinging operation of the dragline plugging is used to
brake, slow, stop or change the direction of swing.
Plugging is actually reversing the power to the swing motors by
pushing the opposite swing pedal. If plugging is used correctly, the
pendulum action of the bucket may be eliminated.
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Pony Motor Drive – A drive system to turn
a motor slowly
A pony motor is a drive system set up on a coupling on a hoist or drags
motor, to allow the drums to be turned slowly to do specific work.
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Positioning / Maneuvering – Walking the
dragline to a predetermined location
Positioning is the same as walking or maneuvering. It occurs when the
dragline is walked to a predetermined area to continue digging
operations. The dragline crew requires the skill to position the dragline
for maximum productivity without compromising the site
requirements of the dig plan. Saving a few degrees of swing with
correct positioning is one way of increasing productivity.
When pulling batters, correct positioning is the difference between a
good, safe, angled batter and one that compromises the integrity of the
batter. Setting up the move before walking, with pegs and a tape
measure ensures the machine is in the right position.
Correct dragline positioning around the block is essential in
maximising payload; and minimising rehandle, swing time, spoil reach
and spoil placement.
After consideration for high wall/low wall stability safety concerns the
best practice approach to determine the efficiency of the positioning of
the tub around the block is to determine whether the majority of cycles
have been disengaged in the zone where the maximum payload occurs.
This can be done by looking at how well the disengage frequency map
matches with the payload vs. disengage map. This can also be done
using the engage distribution but the relationship between payload
and engage point is more difficult to interpret and should only be
attempted by a person experienced in dealing with the data. Using the
disengage approach increases the “trial and error” aspect of the
process but is “easier” to execute. Using the disengage approach is an
expanded version of the rigging vs. digging approach to optimising
rigging. However, in this case the two dimensional analysis provides
more input as to how the operator behaves around the block. The
optimised performance of the dragline with respect to tub positioning
occurs when the peaks of these two dimensional plots are matched.
When it is mismatched a decision should be made as to whether the
rigging will be changed or the tub positioning on the block.
This analysis is not a once-off exercise. These plots should be prepared
every time a report is done and the result interpreted by a person
knowledgeable in this analysis and then communicated to the operator
in sufficient detail to enable a response which will improve and
optimize the overall operation.
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In the following figures for
Payload vs disengage location
and Disengage frequency the
peaks are not matched. In
this example the peak
payload occurs at around 50,10 and the two peaks of
disengage frequency
(bimodal distribution) are at
30,-5 and 40,-15. The
interpretation is that the peak
payload is occurring around
15 metres inside where the
peak payload frequency is
occurring. This dragline
needs to sit around 15 metres
further away from the digging
zone or the bucket should be
disengaged 15 metres further
out.
Payload vs disengage location
How the dragline is
positioned relative to the
digging is only part (but an
important part) of the
optimisation equation. The
positioning should account
for the dumping room as
well. The dumping is an
ongoing operational issue
which relates to being able to
fit all the spoil in the
available space, however
matching the way the
dragline operator is digging
can be coached using
meaningful reports delivered
by a dragline expert.
Disengage frequency
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Post Strip – The material left above the
coal seam that is not able to be reached by
the dragline
As opposed to pre-strip, post strip is that material which is moved after
the dragline has completed its operation.
Post strip is usually a planned operation. When the dragline is
operating at maximum depth and there is a linear dip in the coal seam
over a short length of the pit, the material that is left behind is post
strip, and removed by other means, either by dozers pushing up to the
dig face or a truck and shovel operation.
The following figure shows post strip.
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Power Control Panel – Cabinet for
controlling the power application on the
dragline
This panel has the switches for isolating all the functions of a dragline.
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Power Switching – Electrical term for
turning power on or off
Power switching is usually a term associated with High Voltage
switching.
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Presplit High Wall – When the high wall is
closely drilled and then blasted to create a
fracture line.
Pre-splitting a high wall is a method of producing a safe and
competent wall. Pre-split holes are drilled on the planned high wall
line and at the designed batter angle. The holes are drilled with
spacing’s of between 3 and 5 metres. The holes are then charged with
around 50 kg’s of explosive per hole with no stemming material. The
explosive in the line of drill holes is initiated simultaneously to create a
fracture line on the high wall.
The results of a well-executed pre-split when exposed are the half drill
barrel holes showing in the wall.
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Pre-strip – Lowering the working level of
the dragline
By definition pre-strip is material moved before the dragline. Most
mining companies perform some sort of pre-strip operation. In
dragline operations, the bench is pre-stripped when the depth of
overburden to the coal seam exceeds the digging depth limit of the
dragline. A truck and shovel operation is usually used to pre-strip
ahead of the dragline, but depending on the depth of pre-strip,
scrapers and/or dozers have been used.
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Prime – Spoil in the original bank
before blasting
Prime can refer to the unshot, virgin material or it can refer to the
volume which it takes up. Rehandle is prime which is moved more
than once.
Prime
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Process Delays (Operating Delays) – Wait
on Dozer/Stand Prep (Bench/Pad Prep)
A process (or operating) delay is a stoppage associated with the
operational side of the dragline process. Walking / maneuvering /
positioning around the block, wait on dozer and cable moves are three
of the most common delays. There are many other operational delays.
Many operational delays are under the control of the dragline crews
although waiting on other actions may be outside their control.
Operational delays are associated with utilisation through the generic
formula
Dig time
Utilisation = ---------------------------------Dig time + Operating Delay
Best practice dragline operations keep the dragline swinging
productively and minimise the amount of time stopped.
One of the key operating delays for the dragline is wait on dozer. The
dragline dozer performs a range of tasks around the dragline, some of
which for safety reasons may require the dragline to stop working in
the same area.
The dragline and dozer operators should work together to keep the
dragline digging (productively) for as long as possible. The ‘Best
Practice’ dragline operations have the highest % of Dozer Utilisation.
Best practice draglines often have three person crews and where two
person crews are used will access further labour during the shift to
keep the dozer operating. The following are key aspects to minimising
the time the dragline is stopped while waiting on dozer and
maintaining a safe operating environment.



The dozer should be seen as an integral part of the
dragline operation and should be treated as an area to
report on and improve at all times
The importance of keeping the dragline swinging
should be communicated to the dragline and dozer
operators
The dozer operators should always follow the
standards of the mine.
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A key to the efficient use of dozers around the dragline (keeping the
dragline operating productively) is establishing and maintaining two
digging and/or dumping locations around the block. The next Figure
are showing two pictures how a dragline might have two dig/dump
faces on the one block. In the first the dragline is digging in the key
and dumps behind themselves to fill in the dragline pad. The second
figure shows the dragline digging in the block and dumping around in
the spoil. This is only an example of one option. There is a multitude
of ways to set up dual digging/dumping faces and the aim should be to
maintain this principle at all times.
Dragline with two dig/dump points.
Further to this the second area of safety risk is at the rear of the house.
Dozers working in the swing arc of the dragline boom (at the rear)
should always make their intentions known and be in constant
communication with the dragline operator. All draglines and dozers
should have proximity sensors fitted so that if the dozer comes too
close to the house an alarm sounds. This proximity should be
established by the mine but as a general rule 25 metres from the centre
line of the dragline is a good distance for keeping the dozer away from
the rotating dragline house.
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Process Delays – Walking/Maneuvering
Walking/positioning is the number one cause of lost digging time in
the dragline operation. Walking is essential but it needs to be
recognised as a vitally important aspect of keeping the dragline
available to uncover coal.
The average dragline loses significant time when walking. Every walk
event suffers loss through inefficient set-up (~200 seconds) and
walking procedure (~6 seconds per step). In addition about 1 in 40
“events” recorded as a walk is not a walk. This should be managed.
To minimise loss, crews should be trained and counselled in the
correct way to set up for walking and in conducting walking.
Management should provide focus and reinforcement of the
importance of walking. Central to that is the following;


An SOP in place.
Walk events reporting and follow-up.
Figure 31 demonstrates how time is lost in the process of walking. The
spread of blue points (each of which represents one walk event) above
the pink line (optimal procedure) demonstrates to loss. A plot like
Figure below should be prepared in each report. It plots time and
number of steps for every walk event.
The most important issues to ensure efficient set-up and walking (to
reduce the spread above the optimum line) are;



–
–
–
–
–
Tub positions are planned and indicated on plans.
The decision to walk should be made ahead of the
event (10 minutes minimum) and communicated to
the crew.
Equipment and conditions critical to the walk
prepared.
Walk route prepared
Stability of walk route checked
Cable moved away from the walk area
Winch on rear of house operating and ready
Cable reeler/cable tractor ready as required
In that way when the dragline is ready to walk it can commence
without delay.
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Average W alk
Best Walk
2000
1800
1600
Seconds
1400
1200
1000
800
600
400
200
0
0
5
10
15
20
25
30
No. of Steps
The difference in Y axis intersection are the set-up losses while the
difference in slope indicate the per step losses.
In all analysis the zero walk step events are removed and reported
separately.
The following factors should be reported regularly both with reference
to previous performance and against machine best practice;



Time spent walking (total and average)
Number of steps (total and average) – in particular the
number of zero step walk events
Number of walk events
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Production Monitor – A computerised
machine that gathers the dragline
performance statistics
Production monitors are a necessary piece of equipment in today’s
competitive climate.
Monitors record data namely: cycle time and its sub titles, delay
information both operational and maintenance. The data is then put
into report form so the mine and operators know how they are
progressing against preset targets.
Some monitors record component stresses as well as have GPS
systems.
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Productivity – The amount of overburden
moved in a unit of time
Dragline productivity is of primary consideration to the mine
operating it. Draglines are an expensive machine to operate and
maintain as well as being very expensive to acquire.
The amount of material it moves has a value. The more material it
moves the more the value. It stands to reason that a mine will want to
get the best productivity from a machine that it can.
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Productivity (Make and Model Variance) –
Difference in performance amongst
different makes and models
The following figure shows the 2009-2013 median performance for
each make and model of large dragline.
Dragline Annual Unit Production (BCM/t of RSL) by Make
and Model
Each make and model has declined over time but the primary message
in this plot is the significant differences between different makes and
models. The most productive make and model achieved 106,000 BCM
/ t of RSL while the least productive achieved 66,000 BCM / t of RSL.
The lowest is 38% below the top.
There is an interesting characteristic of this data which is worth noting
and plotting in a different form. The unit capacity increases with
increasing machine size. In the case of draglines this is not a strong
trend but it is gaining strength with time as larger draglines have
tended to perform better relative to smaller draglines over the last
three years. This is demonstrated in the plot in the next figure which is
Output versus RSL. Bigger machines move more than smaller
machines even after the results are modified to normalise differences
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in the RSL. The correlation is good although even with an R 2 of 0.891
the difference between machines of similar RSL can be millions of
BCM per year. By way of example, the two makes and models with
RSL around 250 tonnes achieved 26.7 MBCM and 20.2 MBCM per
year. That 6.5 MBCM difference in material carries a significant value.
Dragline Output versus RSL by Make and Model
1
89% of the difference in output amongst makes and models can be
explained by the difference in RSL.
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Productivity Model (Value Driver Tree) –
Breaking down dragline performance into
its individual components
The use of a model or a “tree” is a useful way of understanding
productivity. It breaks productivity down into the individual
constructs. The following is one example of such a productivity tree.
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The following productivity model / tree demonstrates how values can be added to
the model to demonstrate how the constructs of performance “fit together”. Some
people find this a useful way of displaying productivity and some find it
unfathomable.
Fill Efficiency
8.33
t/sec
SDE
231
kJ/t
Avg. Fill
Time
19.5
Sec
Average
Cycle Time
75.2
Secs
SDE
404
kJ/t
Payload
143.2
t
Av. Drag Load
174
t
Energy
33.1
000 MJ
Fill Distance
19.4
m
Fill Time
17.2
Sec
Fill Rate
1.13
m/sec
Fill Time
51.9
Sec
Fill Rate
0.91
m/sec
Energy
52.6
000 MJ
Fill Distance
47.0
m
Payload
130.2
t
Av. Drag Load
114
t
Fill Efficiency
2.51
t/sec
Repasses
6.7%
Hoist Height
54.1
Metres
Hoist Limited
45.0%
Hoist Rate
2.06
m/sec
Swing Time
28.6
secs
Return
Time
22.6
Sec
Fill Distance
12.6
Bucket Lengths
Total Swings
271,452
Swing
Time
27.6
Sec
Dig
Rate
1,683
BCM/dig Hr
Fill Distance
5.2
Bucket Lengths
Swing Angle
92.2
Deg
Hoist Time
26.3
secs
Dig
Rate
3,702
tonnes/dig Hr
Single Fill
93.3%
Return Angle
99.3
Deg
Swing Angle
105.1
Deg
Swing Limited
55.0%
Swing Rate
3.67
Deg/sec
Return Rate
4.39
Deg/Sec
Spot
Time
5.5
Sec
In-Situ
Density
2.20
Tonnes/CM
365 day
Output
20,991,112
Tonnes
365 day
Output
9,541,414
BCM
Avg Bucket
Factor
35.1
BCM
Average
Payload
77.3
Tonnes
Rated Bucket
Capacity
46.8
CM
In-Bucket
Density
1.65
Tonnes/CM
Dig Time
64.7%
%
Dragline Dictionary
Total Susp.
Load
142.3
Tonnes
Rated Susp.
Load
137.0
Tonnes
Payload
Efficiency
1.19
Ratio
Average
Overload
3.9%
%
Total Steel
Weight
65.0
Tonnes
Bucket
Weight
42.0
Tonnes
Rigging
Weight
23.0
Tonnes
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Productivity Trends – The change in
performance over time
The analysis of draglines used annual output in bank cubic metres
(normalised for full year operation) per tonne of rated suspended load
(RSL). A bank cubic metre is the load in tonnes (as weighed by a
monitor) divided by the in-situ specific gravity (tonnes per cubic
metre). The RSL is a number which the manufacturer places on the
machine as being a safe working load.
The following figure presents the trends in median and best practice
annual output for worldwide draglines from 1994-2010.
Worldwide Dragline Annual Unit Production (BCM/t of
RSL) 1994-2013 by Performance
The peak productivity for draglines occurred in 2004 at around 127
000 BCM per tonne of RSL for best practice and 98 000 BCM/t for the
median dragline. Best practice and median performance declined 14%
and 10% from 2004 to 2010 respectively. Since 2010 the median has
declined to 20% below 2004 while best practice has recovered to be
only 4% below 2004. The difference between median and best practice
was reasonably consistent up to 2009 with best practice being between
30% and 32% higher than the median. Since 2009 this difference has
grown to 56%
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The following figure is a plot showing the differences between median
Australian dragline performance and that in South Africa and North
America (USA and Canada). These are the three predominant areas
where large walking draglines are used. Draglines have been employed
in Northern Africa and Europe but these have not been included due to
lack of data and the generally smaller capacity in the case of Europe.
Similar trends can be seen in each country as is seen worldwide. There
has been a peak between 2003 and 2005 with a subsequent decline.
The decline is particularly evident in South Africa (-27%) and Australia
(-23%). The decline has been less severe in North America (-5%) and
has shown the change in trend in the last three years.
Median Dragline Annual Unit Production (BCM/t of RSL)
1994-2013 by Location
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Propel – Walking the Dragline
Propel is walking the dragline.
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Propel Brakes – Holding mechanism on
the propel function
The propel brakes hold the propel mechanism in the park position
during digging operations.
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Propel Gearbox – The Drive between the
Motors and Cam
The propel gearbox is the drive reduction between the motors and the
cam shaft.
Propel Gearbox
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Propel Motor (Same as Drag Motors) –
The motors that drive the propel function
The Propel motors are the same motors as the drag motors and drive
the walk function
Propel Motor
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Propel Switch – The Switch that changes
Functions
The propel switch changes the drag and propel functions. The drag
lever controls the drag and propel functions, depending on the switch
position.
Propel Switch
on a BE1570W
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Pulling the Limits – Starting the Block
Pulling the limits refers to starting to dig the new block and defining
the front edge of the block. Pulling limits continues until the block is
lowered and the machine moves up to continue deeper digging.
To pull the limits the dragline will be position at the limits distance
from the block line so that the front edge of the block can be defined.
~25m block
Coal
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Pullback - Sitting the dragline on a pad
prepared in the spoil to pull (rehandle)
material higher and further back
Pullback is the term used when the dragline makes a pass down the
strip at a higher level than the previous pass and takes spoil (rehandle)
and pulls it further away from the pit to make room for more spoil in
the pit.
Pullback is a technique used to maximise the amount of spoil the
dragline moves rather than using pre-strip. It is a technique used for
deep digging when the mine is trying to reduce operating costs rather
than uncovering the maximum amount of coal.
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PURSL – Productive Use of RSL
Many draglines have a target suspended load above the rated
suspended load. The PURSL is a measure of how close to the TSL the
actual suspended load (ASL) achieved is and is usually expressed as a
percentage (not exceeding 100%).
PURSL = ASL/TSL (If ASL/TSL > 100% then PURSL = 100%)
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Push Roll – Using the dozer to push the
material pulled up with the bucket
The roll is a mound of material pulled up while loading the bucket at
the dig face. As the roll builds up the drag ropes will pull through it
and can be damaged. It is therefore important that the dozer pushes
the roll back into the pit before the ropes are dragged through the roll.
This will need to be done a few times as the block is dug and the
machine walks closer to the pit.
It is generally accepted that the dragline not dig in the same location as
the dozer pushing the roll. The dragline must either park (stop
operating) which incurs operating delays or work in a different part of
the block. It is for this reason that digging techniques employing two
digging faces have become popular.
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Ramp – Access to a working area below or
above another level
A ramp is used to access an area that is above or below another level. A
ramp is used to access the coal in the pit or a spoil pile. Access to a
dragline that is working on a bench is generally down a ramp.
A ramp is also constructed to allow the dragline to access a higher or
lower working level.
Typical Ramps into Pits
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Rated Bucket Capacity
Rated Bucket Capacity is the standard used for dragline bucket
capacity. If a supplier describes a capacity it will normally be the rated
capacity.
Rated Bucket Capacity = Struck Capacity * 0.9
The struck capacity is defined as the volume contained within the
bucket assuming a perpendicular line going up from the front of the
lip.
The Construction Industry Manufacturers Association (CIMA)
provided a formula for bucket capacity calculation which was used for
many years and the term “CIMA formula” will still be heard. The
bucket suppliers use complex engineering design packages to calculate
struck bucket capacity and will then apply the 0.9 multiplier to
generate the rated capacity. Since bucket capacity has been calculated
with engineering design programs there is a large variation between
suppliers and as such the nameplate capacity has questionable
meaning.
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Reclamation – Re-establishing the waste
spoil heaps to a stable and productive
landform
Reclamation is part of Environmental policies.
The spoil heaps are shaped to create a stable landform on which to revegetate back to a natural shape. The reclaimed land will never be the
same as the original landform before mining, but when reshaped,
topsoil replaced and planted with vegetation, will be productive again.
The state government holds a deposit on disturbed areas until it is
signed off.
Reclamation in Progress
Reclamation a few years old
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Reeving – The action of winding the Ropes
around the drum
Reeving is most commonly referred to as the rope passing over sheaves
(as in IBS ropes) or pulleys. It is sometimes a term for winding the
hoist or drag ropes onto the drums.
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Registered (Mine) Manager – The person
whose role it is to meet statutory (legal)
requirements
The open cut registered mine manager’s role and responsibility is to
make sure the mine complies with all government statutory
requirements. The Registered Mine Manager should have a relevant
Mine Manager’s Certificate which is usually issued by the responsible
Government Department.
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Rehandle – Overburden that is Moved
More than Once
Rehandle is prime overburden that is moved more than once to get to
the final position. In most operations there is some rehandle. Digging
techniques should concentrate on maximising coal uncovery rates
which means rehandle is a key consideration.
It is important that rehandle is calculated as a percentage of the prime
overburden which is handled more than once.
Rehandle % = Total BCM’s – Prime BCM’s X 100
Prime BCM’s
Take careful note of this formula; it is one which many people get
wrong. Notice the numerator is “Prime BCM’s” not “Total BCM’s”.
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Reliability – A measure of availability
The reliability of the dragline is a measure of its availability to operate.
The formula for reliability of a system or individual component is;
Reliability = MTTF/(MTTF + MTTR)
Where
MTTF = Mean Time To Failure
MTTR = Mean Time To Repair
While availability is the term used for the overall dragline operation
reliability is normally associated with individual components.
Operate for Reliability
Stress/damage on the dragline is not a function of the load
being carried (the correlation between load and damage is
very low); it is a function of what the operator is doing with
the dragline.
To keep the dragline operating, as many “damaging” activities should
be eliminated from the dragline operation as possible. Telling the
operator to reduce payload is NOT an “Operate for Reliability” action.
Each action of the dragline places stress on different components of
the dragline, some of which are more detrimental than others.
Furthermore the pursuit of productivity places greater pressure on the
operator, who then controls the machine to do more work in a shorter
period of time, which translates into increased stresses on the machine
itself. There is an increasing desire to ‘push the limits’ and with this
comes the need to know exactly what are the physical and mechanical
‘limits’ of the dragline. All best practice dragline operations have
maintenance loggers and actively use the data. These loggers monitor
the stresses in the major components of the dragline.
The types of damage/stress incurred on the dragline can be broken
into two general categories; ‘cyclical’ and ‘anomalous’.
Cyclical damage/stress will be the baseline damage which occurs
simply due to the action of the dragline. Effort is being made to
understand what constitutes a reasonable baseline and once this is
better understood effort will be directed towards investigating ways
and techniques of operating that lead to a reduction in the cyclical
damage (e.g. dumping a different way, disengaging within a specific
zone, etc.).
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Anomalous damage/stress is the damage caused when the dragline
does something which is outside the sphere of ‘normal’ operations. An
example of anomalous damage is the repetitious throwing of the
bucket to reach the toe. This is considered anomalous as there should
be ways of avoiding such casting, i.e. different tub locations, strip
widths, block lengths etc. There are many examples of anomalous
damage events. Better measurement and communication of the
occurrence and damage implications of these ‘anomalous’ events has
been shown to translate to lower damage and higher productivity.
Some of the actions that produce ‘anomalous’ stress and should be
actively eliminated are;








Swinging Before Disengage
Hoisting While Dumping
Payout While Dumping
Hitting Spoil Pile with Loaded Bucket
Dumping on the Fly
Engaging Close to the Drag Limits
Throwing the Bucket
Chopping








Lever Jockeying
Tight-lining
Sinking the Dragline
Not Gathering Drag Ropes while Dumping
Slapping Fairleads
Short Dumping
Taking Half Bucket Widths
Back Bucketing
The issues in the left column are the higher priority to eliminate,
however, all of these 16 activities increase the stress/damage on the
machine and will impact productivity and dig time at some point. The
relative impact of 11 of these actions on the boom foot compared
against normal underhand digging is shown in Figure 38.
Operating for reliability means actively measuring what the dragline is
achieving in terms of productivity/output and stress/damage and then
using the information to help the operators change poor actions.
There are a number of principles which most of these factors fall under
which contribute towards reducing stress and increasing output;
1.
2.
3.
4.
Keep the operation smooth.
Keep the bucket in the boom plane.
Keep the bucket as far away from the boom as possible
Keep movement (hoist and swing) to an absolute minimum
during dump (except for drag payout).
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0.00
Dragline Dictionary
Bo un ce to S in k
M ult i-pa ss
Tig ht lin e
Ba ck Bla de
S wi ng Bu cket
Ou t
Jar Ro pes
Du m p
L owe r Wh ile
Ho is t Wh ile D ump
Clip S po il
Du mp o n t he Fly
N or mal Ove rh and
No r mal
U nd erhan d /Cho p
Relat ive D amag e
Bo omFo ot
3.00
2.50
2.00
1.50
1.00
0.50
Stress/damage inducing events.
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Repass (Multiple Pass) – Dragging the
Bucket in more than once to fill it
Repassing or multiple passes refers to the action of an operator
disengaging a bucket at the drag limits and taking it back to have
another attempt to fill it properly. It should be minimised as it is
unproductive. There may be times, especially when defining (pulling) a
batter when it cannot be avoided. Under normal operations it is only
poor operating practices that contribute to this practice.
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Re-route (Cable) – Reposition a power
cable so it comes to the dragline from a
different location
Cable re-routing takes place fairly regularly as the dragline progresses
along the pit. The route is planned and the access built and graded.
Then a cable is laid out into position before the power is cut to the
machine. After reconnection, the unused cable is rolled up and taken
away for storage.
Planners and operational must ensure cables are available for the
entire length of a pit. It is embarrassing when a dragline reaches the
end of its cable and there is no alternative cable in place to continue
the strip.
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Reserves – The Total Tonnes of Coal
Available to be mined
When an exploration lease is granted to a coal mining company, they
undertake a drilling programme to estimate the amount of coal
available for mining. This is the coal reserves, which is the portion of
the resources which has a reasonable chance of economic extraction.
Reporting is done to comply with JORC (Joint Ore Reserves
Committee) standards.
When the mine is operational the reserves are re-quantified yearly as
coal is mined.
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Return Time – The Time it takes to Swing
back to the Pit
Return time is part of the dragline cycle time. It is the time it take to
return from dumping the spoil from the bucket to the time the bucket
engages in the bank to fill again.
Returning the bucket is normally more difficult to control than
swinging with a loaded bucket.
The interpretation of return time is confused by “other” actions the
dragline may undertake when it has “completed the dig, swing dump
actions. Theoretically, return time should be shorter than swing as the
bucket is empty and the hoist is lowering, not raising. In practice, the
return time may include a range of anomalous time which isn’t really
returning and can in some cases end up being more than the swing
time.
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Revolving Frame – Main Chassis of the
Dragline
The revolving frame is the main chassis of the dragline. It sits just
above the tub on the swing rollers and rotates as required. All the
working machinery; A frame, gantry, mast and boom, and house are all
attached to the revolving frame.
Revolving Frame
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Rigging – The chains and associated parts
that attach the bucket to the drag and
hoist ropes.
The rigging is all the chains and all other associated connecting parts,
that attaches to the bucket one end and the drag and hoist ropes the
other end.
Note: Rigging does not include the bucket.
Rigging Rigging
Excluding
the bucket
To facilitate efficient bucket performance, optimal rigging set up is
required for the bucket and digging (rigging to the digging), including
dump rope length for proper carry angle, location, depth. Mines
should to be mindful of the fact that suppliers make significant margin
from rigging and the bucket is often only a tool on which to hang the
supplier’s rigging.
As is the case with buckets, mines should proactively choose rigging
which will facilitate optimal dragline and bucket operation. Figure
below shows the variation in payload vs. carry angle of the bucket. It is
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the rigging which dictates the carry angle and as such optimising
rigging is key to best practice operations.
Bucket payload vs. carry angle
The key aspects to the application of rigging are;
a.
b.
c.
d.
e.
f.
Full Range of Operation, e.g. Disengage at fairleads (up to 45o),
dumping high (down to -900), etc. without interaction with any
part of the bucket or rigging.
Minimise weight of the rigging
Minimise number of components
Stability/rigidity during swing and return
Consistency of disengage carry angle and minimise nodding
during disengage away from fairleads
Dump Rope Issues
–
–
–
Single dump rope setup used where possible
Load During Disengage
D:d ratio of dump sheave(s)
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–
–
Lay of the rope
Likely external damage
After the achieving of the full range of movement minimising the
weight is the next most important issue. As a reference the table below
shows the average rigging weight used by best practice draglines. If
the specific dragline RSL on a site varies from that noted multiply the
specific dragline RSL by the rigging weight/RSL ratio.
Dragline
Best Practice
Dragline RSL
(metric
tonnes)
Best Practice
Dragline Rigging
Weight (metric
tonnes)
Best
Practice
Dragline
Rigging
Weight/RSL
BE 1260W
73.0
13.6
0.186
BE1300W/1350W
81.8
15.7
0.193
BE 1360W
102.3
18.0
0.176
BE 1370W
134.5
21.3
0.158
BE 1570W
159.1
23.7
0.149
BE2570W/2570WS
260.8
40.0
0.153
Marion 8050
132.7
22.4
0.169
Marion 8200
170.5
25.7
0.151
Marion 8750/8200S
215.4
29.1
0.135
P&H 9020
218.2
37.3
0.171
Data accessed from PwC Databank. Current until 31 December 2013.
The optimisation of rigging is a simple process utilising data analysis.
The payload vs disengage distance is plotted along with the plot of
frequency vs disengage distance. This can be optimised visually by
aligning the two peaks. Figure below shows optimised rigging while
the Figure after that shows a poor rigging set-up.
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Rigging to the digging analysis – Optimised Rigging
Rigging to the digging analysis – Poor Rigging
In the case the dump rope/s require shortening by one metre.
Stability/Rigidity is a function of how much bucket movement there is
during swinging. This is calculated from changes in carry angle, (front
to rear rocking), and dump rope loads, (side to side rocking).
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Disengage Carry Angle is optimised to produce the most consistent
disengage carry angle. To quantify this, the payload (or BER) vs
minimum disengage carry angle is determined. This can be used in
conjunction with the disengage distribution and the steel weights to
determine the theoretical impact on payload.
The two factors which influence dump rope life are damage and load.
Damage is caused internally, (over the block), and externally, (rubbing
against other parts of the bucket or rigging – usually the dump block).
Internal damage will be assumed to be consistent. External damage
will be assessed based on
The “fleet” angle of the dump block, i.e. rotational attitude of the
blocks, and
Impact of stability. The more movement the more damage which is
likely to occur.
Many mines now have larger draglines which require a double dump
rope arrangement. A series of “rules” have been developed to set
double dump rope rigging up correctly and for management to
evaluate options brought to them by suppliers.
1.
2.
3.
4.
5.
Connect dump ropes to the bucket arch with the maximum
separation possible.
Design the upper spreader arrangement to ensure the dump block
separation is equal to the dump rope lugs on the arch.
Allow the widest possible separation of upper hoist ropes both to
the lower spreader bar and the upper spreader arrangement
Allow maximum degrees of freedom of the dump blocks
Minimise weight while maintaining structural integrity
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RL – Reduced Level
RL (Reduced Level) is the height/depth from a datum point used by
Surveyors. It is a term which is used frequently around the dragline
operation.
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Rock Drain – A trench to contain
falling / rolling rocks.
A rock drain is gouged by the dozer and at times by the dragline, to
contain rocks dumped from the bucket that roll down the spoil. It is
dug near the base of the spoil heaps and stops the rocks hitting the
dragline and causing damage.
Note
– as
Note—as
drain
fills,
drain
fills,
rocks
areare
rocks
getting
getting
through
through
the
the drain
drain
In really rocky conditions, more
than one drain is recommended
as some rocks penetrate the first
drain defence.
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Roll – Mound of Material the Bucket Pulls
up while digging a Block
As a dragline digs, the bucket and chains pull up some overburden and
this action creates a roll. The minimise damage to the drag ropes if
they are pulled through the roll, the dozer is used to push the roll back
into the pit. The roll will have to be pushed a few times as the dragline
lowers the pit depth, and until the machine is up to the dig face.
When pushing the roll, it is important that the dozer doesn’t round
over the dig face but keeps a square face as the dragline will sit in that
position when it is at the face.
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Roll a Bridge – Moving a bridge to mine
the coal beneath it
There are times when a bridge of spoil is left across the pit, usually as
access to the spoil for a truck and shovel operation.
When a dragline digs a pit and comes to a bridge left in a pit, it has to
be moved to expose the coal that is left underneath. This is called
rolling the bridge. Rehandle will increase significantly around the
bridge.
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Roller Circle – The Roller Circle carries the
Entire Weight of the Dragline.
The roller circle is positioned on the dragline tub, and carries the
weight of the machine. The roller path is attached to the tub and the
revolving frame.
At least once a shift, the operator should swing a full circle to
reposition the load carrying area of the path and rollers.
Roller
Circle
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Rope Trays – Containers in the house that
hold material that drops off ropes
The rope trays are located in the machinery house, under the drag
ropes. They are designed to catch and contain the material that drops
from the ropes including excess lube and overburden.
The trays are cleaned regularly, usually on maintenance days.
Drag rope tray on a BE
Drag rope tray on a
Marion
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Roster – A Dragline Crew’s Working
Arrangement
Most mines work 24/7 and have had to arrange a shift working
arrangement with their workforce. There are just about as many shift
rosters as there are mines in this industry, and most mines negotiate
the most suitable roster with their workforce.
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RSL – Rated Suspended Load
The Rated Suspended Load, RSL, is the specified total load
recommended by the manufacturer. Most mine owners of the older
machines are challenging, with due diligence, the specified RSL and
increasing the RSL by up to 25%. Boom studies and duty meters are
being used to allow mines to overload the previous rated suspended
load.
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Safety – Efficient mines are generally safe
mines
Safety is non-negotiable. Best practice mines are safe mines. Safety
and productivity are underpinned by the “right” attitude.
Recent research has shown that performance and safety are correlated,
(Van Den Raad, 1999, Foster and Wheeler, 1999 and Demby, 2009). In
fact Foster and Wheeler (1999) found that the correlation between
safety and productivity (R) is 0.79. This correlation is “very high”.
Demby (2009) suggests that the link between safety and productivity is
something most people believe exists. It seems logical that workers
work better when they're protected against injuries. Further to that,
workers who are not involved in safety incidents or accidents can keep
on working productively; safety improves morale and workers are
more likely to work effectively on the job; and the discipline of
assessing risks, identifying what can go wrong and taking measures to
prevent occurrence not only improves safety but makes the production
process more efficient. Van Den Raad (1999) demonstrated the link
between productivity and safety on a cattle farm and meat processing
factory. They found the productivity was impacted by 4% due to a
focus on safety. A further correlation is concluded through the work of
Lumley (2007) and Gladwell (2009). Lumley (2007) found that
performance had a strong link to abilities. It seems obvious that
selecting the “right” people could be a fundamental first step in
creating the safest possible work environment and given the fact that
Lumley (2007) developed a method for selecting highly prospective
(on the basis of productivity) people, this same approach could also
select the safest people as well. Given the high focus of mines on safety
it is not surprising that high performing individuals are going to be
attracted to mines that have a real safety focus. There is an important
distinction here. Some mines take the “butt-covering” approach to
safety management and there is no evidence that the legalistic
approach has any link to safety performance.
Research has also shown across a range of industries that good
communication leads to enhanced safety outcomes. Good
communication should transcend ALL boundaries, including, national,
cultural, company level, seniority, and gender. Good communication
doesn’t just happen; it should be planned, executed and reconciled on
an ongoing basis.
The development and use of Standard Operating Procedures (SOP’s) is
an integral part of a Best Practice quality and safety system as they
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provide individuals with information to perform a job safely and
correctly, facilitating consistency in the quality and integrity of the
end-result. A proper SOP will embody the full knowledge and
understanding of the organization on a particular process.
See the separate entry under SOP.
Safety issues may arise either as part of an SOP or outside of the SOP’s
which require a response. Best practice in mining operations is a
communication system which ensures issues are communicated with
required urgency to those people who need to respond. This is done
either through telecommunication networks or site based “wireframe”
coverage (through 2-way frequencies / 3G, etc.) The system should
facilitate urgent issues reaching people immediately wherever they are.
Smart phones and online systems are used extensively.
Of great importance to communications is the availability and use of
dedicated “line-of-sight” communications for each piece of mining
equipment. The dig and loading area is a high risk area for accidents
and reduced performance. It is the key area where efficient operations
should happen. Effective communication in this area is important for
reducing the risk of an accident and optimising the work. Each piece of
equipment has significant blind areas. It is an area where the crew
should work together effectively. The extensive use of digital camera
systems on almost every type of heavy mobile equipment is a tool to
assist in this area but personal responsibility and verification of “clear
to proceed” is of prime importance.
Each operator, his direct crew, plus any person working in the
operator’s area of responsibility shall be in direct contact with the
operator by means of a 2-way radio.
Best Practice operations have a dedicated “line of sight” radio channel
or 3G based system ensuring an uninterrupted line of communication
that can and is used to ensure that no interruptions inhibit
communication with the operator for safety instructions and or
operational instructions.
In addition, signs posted as reminders provide information to visitors
to work areas and should be used to communicate all critical
procedures.
The superintendent should have access to all channels / systems used
by the equipment under their responsibility. The superintendent /
foremen should be accessible wherever they may be on the mine site.
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Safety Rill – A Small Berm or Bund
A safety rill is usually a smaller version of safety berm or bund and is
also used where a significant drop in spoil level exists. It is usually
constructed by a grader, about half metre in height, and is used where
only light vehicles access the area.
As with berms it is now a requirement in some jurisdictions that a site
be able to “prove” that the barrier is sufficient to stop a vehicle likely to
be operating near it.
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SDE – Specific Dig Energy
Some monitors provide a measure of ‘diggability’. This measure is
difficult to understand and appears to be frequently inaccurate. A
better measure of diggability is defined by Specific Dig Energy (SDE)
which is a function of the fill energy and payload.
In hard digging, the fill distance and drag loads tend to increase which
increases fill energy, while the payload tends to decrease. Within a
mine site, the SDE will provide a good indication of how hard the
digging is and/or how efficient the blasting.
Specific Dig Energy
=
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SDO – Specific Dragline Output
Current measures of dragline productivity do not allow a valid
comparison between draglines due to the confounding variables (e.g.,
make and model of the dragline, bucket being used, etc.). To provide a
valid basis of productivity comparison between operators a new
measure of productivity has been developed.
A dragline digs a bucket load of spoil (payload) and carries it through
an arc equal to the swing angle before dumping it and returning the
empty bucket. The total output of the dragline is payload multiplied by
number of cycles, and the productive output is total output divided by
unit time.
Productive Output
=
payload * number of cycles
unit time
The variables to be controlled for so that they do not confound the
productive output are: dragline class; swing angle; size of the dragline
and the type of bucket being used (correction for MRC); and the
diggability of the spoil being dug. The Dragline Output (DO) corrects
for the dragline class, swing angle and the diggability of the spoil.
Dragline output will normally be expressed as cubic metres per hour as
this is an industry standard expression. A cubic metre represents the
volume taken up by one cubic metre in the undug spoil.
When comparing a single dragline with the same bucket over a period
of time, this is a suitable method of comparing productivity.
DO
=
payload * number of cycles * ( F MM *FSA * FD)
unit time
The final confounding variable is bucket type. To control for different
buckets and different capacity buckets the Dragline Output is divided
by the MRC. The resulting productivity measure is called the Specific
Dragline Output (SDO).
SDO
=
payload * number of cycles * ( F MM *FSA * FD)
unit time
______________________________
MRC
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The units of Specific Dragline Output will most commonly be
expressed as cubic metres / hour / tonne.
Sample calculations
Dragline
-
BE1370W
Bucket
-
48 cubic metres Conventional
Average Payload
-
100 t
In-Situ Specific Gravity
-
2.2 t/cubic metres
Average Fill Time
-
15 secs
Average Competency
-
4
Average Swing Angle
-
95 deg
Reference Angle
-
100 deg
Peak Swing Speed
-
9 deg/sec
Peak Return Speed
-
11 deg/sec
Average Cycle Time
-
69 secs
From PwC data,
FMM
=
1.018
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MRC
=
BER P95 * RBC
BERP95 =
2.07 t/cubic metres
MRC
=
48 * 2.07
=
99.4 tonnes
FSA
=
1
+
2 * ( SA ref –SAave)
SRpeak * CTave
FSA
=
1
+
2 * ( 100 – 95 )
[(11+9)/2] * 69
FSA
=
1.014
FD
=
1.09
=
payload * number of cycles
unit time
Productive Output
The payload is converted to cubic metres by dividing by the specific
gravity of the spoil. The number of cycles is one because the results
are averages and unit time is the average cycle time.
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Productive Output
DO
=
[(100 / 2.2) * 1 ] / 69
=
0.66 cubic metres / sec
=
2,371 cubic metres / hr
= payload * number of cycles * (F MM *FSA * FD)
unit time
= 2,371 * 1.018 * 1.0159 * 1.09
= 2,673 cubic metres / hour
SDO
= payload * number of cycles * (F MM *FSA * FD) / MRC
unit time
= 2,673 / 99.4
= 25.9 cubic metres / hour / t
The following table shows a number of different draglines digging
different conditions and how the calculation of Specific Dragline
Output allows a valid comparison.
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Dragline
Dragline
Model
Make
1
&
2
3
4
5
BE1370
W
M8750
M8050
M8200
BE1370
W
Bucket Type
Conv.
Conv.
Scoop
Scoop
UDD
Capacity
48 m 3
85 m3
33 m3
47 m3
57 m3
Payload
100 t
165 t
104 t
132 t
116 t
In-Situ S.G.
2.20 t/m 3
2.20 t/m3
2.20 t/m3
2.20 t/m3
2.20 t/m3
Fill Time
15 secs
13 secs
16 secs
18 secs
14 secs
Spoil Competency
4
3
3
2
4
Swing Angle
95 deg
92 deg
90 deg
120 deg
95 deg
Reference Angle
100 deg
100 deg
100 deg
100 deg
100 deg
Peak Swing Speed
9 deg/sec
8 deg/sec
9 deg/sec
8.5
deg/sec
10
deg/sec
Peak Return Speed
11
deg/sec
10
deg/sec
11
deg/sec
10.5
deg/sec
12
deg/sec
Cycle Time
69 secs
68 secs
62.5 secs
71 secs
63 secs
MRC
99.4 t
175.0 t
102.3 t
145.7 t
119.1 t
Specific D/L Output
25.9
cubic
metres /
hour /
tonne
24.4
cubic
metres /
hour /
tonne
25.5
cubic
metres /
hour /
tonne
19.3
cubic
metres /
hour /
tonne
27.0
cubic
metres /
hour /
tonne
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Seniority – First on, First off
For many years in the mining industry, seniority was used to fill
positions in a dragline operation.
In the present time, tools are available to select the appropriate people
for the position, resulting in a more productive dragline workforce.
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Service Roads – The Vehicle Access around
a Mine
It is important to have well designed and maintained service roads
around a mine site.
These roads give vehicles and equipment access to the working areas of
the mine. Service roads to the dragline, especially as the local
environment to these machines can change regularly, needs to be
maintained in case of safety issues that may arise.
A well designed and constructed service road
SG – Specific Gravity
Specific gravity is the term used for describing the density of the
overburden or coal.
The correct density entered into the production monitors, should give
a closer correlation of the monitor production results to survey results.
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Shale – Fine grained material usually
found with Coal Seams.
Shale in a coal mine is usually found in layers above and/or below the
coal seam. Sometimes, especially during hours of darkness, it can be
mistaken by the operators for the coal seam, as it sometimes has visual
properties much like coal, i.e. it is dark. In the accompanying picture
the partings are shales.
Coal
Seams
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Shift – A crew working a roster
The shift is the time worked on the job. A crew or a group of people
work a particular roster. Some rosters have night, day and afternoon
shifts. 12 hr shifts have day and night shifts.
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Shift Briefing – A pre-shift talk with the
crew
The shift management usually has a briefing with the crew before the
start of a shift. The discussion points are usually centred around safety,
operational and production issues. This session is succinct and usually
only takes 5-10 minutes but is necessary to keep the crews informed.
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Shoe Guides – A device to keep the shoes
in position
Different dragline manufacturers have their own ways of guiding the
shoe during the walk cycle.
Some individual mine have also modified the guide system on their
draglines to better cope with the conditions of their mine.
Shoe Guides
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Short Dumping – Dumping inside the
Normal Dump Radius
At some time during normal operations, an operator will short dump
to fill in an area inside boom dump point. It is a bad practice as it does
anomalous boom damage. It should be minimised by correct
positioning of the dragline.
To short dump, the drag is brought in from boom point, quickly payed
out to allow the dump action of the bucket. If not done correctly, it will
do more damage as the bucket catches up with the drag ropes as the
payout and can jarr the whole machine.
It should be noted that almost all dragline dumping occurs inside
boom point due to the dynamics of loading in the dump rope and the
projection of spoil back towards the dragline.
Dragline Dictionary
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467
Shot ground – Blasted overburden
Overburden that has been blasted in preparation for the dragline
digging it is described as shot or blasted ground. As soon as the
overburden is blasted, it should be leveled to seal it and stop a rain
event affecting it by entering the fractured ground. The word shot can
also apply to the act of blasting, as in “To let the shot off”.
Shot Ground prior
to being levelled &
sealed
Dragline Dictionary
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468
Side Cast – Dumping to the side of the
block
Side casting the overburden is when the dragline dumps into the void
up to around 90 degrees to the high wall.
A Dragline Side Casting
Dragline Dictionary
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469
Sidewinder – A branded, mechanical
means to attach an adaptor to the nose of
the bucket with a side pin
The Sidewinder is an ESCO ® branded product to attach the adaptor to
the nose of the bucket.
It uses a thread action to expand into the nose hole and hold the
adaptor in position. This fitting does away with having to use a sledge
hammer to drive a wedge into the hole as there have been numerous
incidents of flying chips of steel injuring people.
Sidewinder
Dragline Dictionary
T: +61 7 3257 5000
470
Signage – Signs around a mine site
Signage is the collective term for the different types of signs around a
mine site.
Dragline Dictionary
T: +61 7 3257 5000
471
Signage Rack – A place to store unused
signs
Most mines have a number of racks to store signs when not in use. It
makes good housekeeping and is easier to find a sign when required.
Dragline Dictionary
T: +61 7 3257 5000
472
Signal Bell – A device to attract the
operators attention
The signal bell is located in the operators cab, and is used to attract the
operators’ attention as well as letting the operator know what is
required.
Signal Bell
Signal Bell
Dragline Dictionary
T: +61 7 3257 5000
473
Signal Control Switch – The switches used
to send a signal to the bell in the cab
The signal control is a pull switch that is used to send the required
signal to the operators cab.
These switches are situated in many of the working areas of the
dragline, inside and outside.
A Typical Pull Switch
Dragline Dictionary
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474
Simulator – A device that simulates actual
conditions
A simulator is a test machine that gives the learner operator a similar
feel to the real machine. Immersive Technologies Pty Ltd is the major
Australian manufacturer of simulators. They have developed dragline
as well as truck and shovel simulation.
There are a number of other simulators in the Australian market. They
are produced by Dassault (CAE) - French, 5DT and ThoroughTec, both
South African companies.
The dragline simulators are considered good tools for novices but may
not be so useful with experienced operators.
Dragline Dictionary
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475
Single Pass – Exposing a Single Seam of
Coal
A single pass operation is when the dragline exposes a single coal
seam.
Dragline Dictionary
T: +61 7 3257 5000
476
Sink – When the Weight of the Dragline
pushes the Tub into Soft Material
As the dragline is a very heavy machine, there are times when working
with incompetent material, the machine will sink and will need to be
repositioned to continue working. The dragline is then walked out of
the sink and the dozer will fill the hole with material to the original
height. The dragline is then walked back into position.
Dragline operations are affected more during wet weather as the water
getting into the overburden creates soft spots in the bench. Recovery
of the dragline in these instances can be difficult and time consuming
and damage can occur during the recovery process.
Sink caused by water
getting into the
bench and creating a
soft spot
Dragline Dictionary
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477
Sling – Rope used to pull the Trailing
Cable
A sling is a hemp rope or nylon sling used to pull the trailing cable.
Two slings 1-2 metres apart are hitched onto the cable and a maximum
of 25 metres are pulled at one time, so damage to the inner core of the
cable is minimised.
The slings are made from a hemp rope of 19-25mm diameter so they
will break should the cable come under too much stress when being
towed.
Dragline Dictionary
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478
Sockets – Used to Attach Ropes to the
Chains
Sockets and wedges are used to attach the hoist, drag, and dump ropes
to their respective chains.
Dragline Dictionary
T: +61 7 3257 5000
479
SOP (Standard Operating Procedure) –
Undertaking a job in a safe and efficient
manner using a prescribed approach.
The development and use of Standard Operating Procedures (SOP’s) is
an integral part of a Best Practice quality and safety system as they
provide individuals with information to perform a job safely and
correctly, facilitating consistency in the quality and integrity of the
end-result. A proper SOP will embody the full knowledge and
understanding of the organization on a particular process.
An ongoing process should be in place for determining what
procedures or processes need to be documented. SOP’s should be more
than a legalistic approach to ensuring managers don’t go to jail in the
event of an accident. They should be written from the perspective of
what is the best way to conduct a procedure which adds the most value
(and of course that includes both safety and productivity; which are
closely correlated). Those SOP’s should be written by individuals
knowledgeable with the activity and the organisation's internal
structure. These individuals are essentially subject-matter experts who
actually perform the work or use the process. A team approach is best
followed, especially for multi-tasked processes where the experiences
of a number of individuals are critical. This also promotes “buy-in”
from potential users of the SOP.
Operational SOP’s may include but not be limited to:

Emergency Procedures

Dragline Boarding Procedures

Operating Zones & Exclusions

Strata Inspections and Special Area Management (ground
control)

Start up and Shutdown of Equipment

G.E.T (Ground engaging tools)

Operating Procedures

Transport Route and Ramp construction

Ancillary Equipment

Power Access
Dragline Dictionary
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480
Spoil (Waste) – All material removed from
above a coal seam (overburden) or from
between seams (interburden).
Spoil is the waste material above a coal seam or between multiple
seams. With a dragline operation the waste material is dumped to
spoil.
Next strip
Spoil
Spoil
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481
Spoil Heaps – The piles of waste Material
after the dragline has uncovered the coal
As the dragline digs each block, the excess spoil is dumped into heaps,
building a row of spoil heaps.
Spoil Heaps
Dragline Dictionary
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482
Spoil Pullback – Move Spoil further away
from a Pit.
Spoil pull back is used when the dragline is spoil bound and needs to
make more spoil room.
A ramp is made to get the dragline up into and behind the spoil row to
be removed to make this room. That spoil is then swung 180 degrees.
Spoil to be
pulled back
Spoil pulled back
A Completed Pullback
Dragline Dictionary
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483
Spoil Room – The amount of available
space to dump waste material
Spoil room is the area available to dump the waste material.
All operations have different digging conditions and spoil room
available. In many mines the operation of the dragline is more an
exercise in fitting the spoil into the available room than where the spoil
is coming from.
An operation with
shallow digging &
plenty of spoil
room available
An operation with
maximum dig
depth and tight
spoiling
Dragline Dictionary
T: +61 7 3257 5000
484
Spot Time – The time difference between
cycle time and the combined parts of the
cycle
Cycle time is made up of fill, swing, dump, return, and spot time.
Spot time is the time left after fill, swing, dump and return time are
taken from the total cycle time. Leica/Tritronics monitor’s algorithms
may cause a mismatch between the time measured for a cycle and the
sum of the components. This is called spot time. Pegasys and Aquila
do not have this same issue and should record zero spot time.
Where Spot Time is recorded it should not be used as a measure of
dragline nor operator performance.
Where spot time is recorded a study of spot times on a cycle by cycle
basis shows spot time to be predominantly low (0-1 second caused by
rounding errors) with double spikes of much higher values. The
spiked values often occur when the dragline is stopping and is due to a
failure in the cycle identification algorithms for the cycle leading into
the stoppage and the cycle immediately after the stoppage. A similar
double spike is sometimes also seen in return times.
Spot Time
Seconds
20
15
10
5
0
Minutes in Shift
Time
Dragline Dictionary
Average Spot Time
T: +61 7 3257 5000
485
Spotting the Bucket – Placing the bucket
accurately in the bank
Spotting the bucket with precision is what operators need to aspire to,
as some dig time can be wasted with poor placing of the bucket. The
return component of cycling is probably the hardest to master and to
do consistently in an optimised manner. Despite being empty, the
dragline may slow returning speed to allow the bucket to be accurately
placed in the spoil. It is the part of the cycle which suffers the greatest
operational losses in the cycle.
Dragline Dictionary
T: +61 7 3257 5000
486
Spreader Bar – Fitted between the Upper
and Lower Hoist Chains.
The spreader bar is situated in the rigging between the upper and
lower hoist chains and is there to keep the hoist chains spread so they
are kept away from the bucket.
On arch-less buckets like the scoop, a small spreader bar is added to
the dump rigging also.
Dump Spreader
Bar
Hoist
Spreader
Bar
Dragline Dictionary
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487
Step Length – Length of a Dragline Step
The length of a dragline step varies from one make of dragline to
another. Most machines take a step of approximately 2 metres. Large
draglines have longer steps.
Dragline Dictionary
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488
Strip Cut – The Subsequent Excavations
after the Box Cut.
After the initial box cut excavation, all the other excavations done with
the dragline are generically called strip cuts. This is due to the long and
relatively narrow pit layout.
A strip cut is an excavation that has a free face on the void side of the
pit.
The next strip cut
being drilled
Dragline Dictionary
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489
Stripping – Digging overburden
Stripping is the generic term for dragline digging. It refers to the
dragline digging the overburden to expose the coal.
Dragline
Stripping
Overburden
Dragline Dictionary
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490
Stripping Ratio
Prime Cubic Metres per tonne of coal.
Need to always define what tonnes are being referred to as can be in
situ coal, run of mine coal, or clean (washed) coal.
Stripping ratio is often used in planning and reconciliation (after
survey pick-up. Of minimal value in actual dragline operation due to
rehandle.
Stripping Ratio = Prime Cubic Metre/tonne of coal
Dragline Dictionary
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491
Struck Bucket Capacity
Struck Bucket Capacity is the contained volume inside the bucket
assuming a line is drawn perpendicular from the floor of the bucket
intersecting the front of the lip.
This is normally calculated using suppliers’ computer models but can
also use CIMA formula. The CIMA formula should be used by mines
when the supplier’s nominated capacity is not known.
Struck Bucket Capacity = Ave length * Average Width *
Ave Depth * F
Where F is a form factor accounting for the rear
curvature and normally is between 0.87 and 0.97. (0.95
is the most common).
Dragline Dictionary
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492
Stub Line – A feeder power line
The main power line to the dragline is usually placed outside the pit
excavation parameters. The power is then brought closer to the
working pit by a feeder line called a stub line. Stub lines are placed at
around 1km apart along the pit length so the dragline can access the
power. Most draglines with external substations will operate effectively
with a maximum of 2100m of cable from the substation.
As the pit advances, sections of the stub line can be removed as
required.
Main
Power
Line
Stub Line
Stub Line
Termination
Dragline Substation
Dragline Dictionary
T: +61 7 3257 5000
493
Substation – A high voltage transformer
A dragline substation is portable to be able to move it to the required
location as the dragline progresses along the pit.
The substation or sub, converts the 66,000 kv power from the mains
power to the 6,600kv that the dragline requires.
Dragline Dictionary
T: +61 7 3257 5000
494
Survey – Quantified analysis of an area
Survey is an accurate calculation of an area using sophisticated optical
and electronic equipment.
The mine surveyor is responsible for setting out the pit area for the
dragline to dig.
Most progress surveys are performed on a weekly and end of month
basis so production personnel know how they are tracking against
targets.
Dragline Dictionary
T: +61 7 3257 5000
495
Sweet Spot – The disengage zone where
the bucket payload is maximised
The bucket disengage sweet spot is when the operator can efficiently
lift the bucket out of the bank without spilling too much payload from
the front of the bucket.
The length of the dump rope affects where the sweet spot is located in
the dig zone, and using the PwC “rigging to the digging” graph, the
dump rope length can be determined.
For a conventional bucket, measuring the carry angle and setting the
dump rope so the angle achieved is 35.5 degrees and a skilled operator
optimising disengage techniques, will go a long way to maximising use
of the sweet spot, and therefore improving productivity.
Sweet Spot
Dragline Dictionary
T: +61 7 3257 5000
496
Swell – The enlargement of the in-situ
overburden after blasting
Overburden swell is the enlargement of the Insitu overburden after
blasting.
Blasting loosens up the overburden, creates air pockets within the
burden and therefore taking up more volume.
Swell of 25% is considered normal although this can vary significantly.
Dragline Dictionary
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497
Swell Factor – The percentage of
enlargement of the in-situ overburden
after blasting
The swell factor is the percentage of enlargement of the Insitu
overburden after blasting.
Dragline Dictionary
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498
Swing Angle – The angle of the arc the
boom travels through from disengage to
dump.
The swing angle is the degrees of swing between disengage location
and dump location.
Best practice machines average 95 degrees.
Swing Angle
Dragline Dictionary
T: +61 7 3257 5000
499
Swing before Disengage (Pulling out of the
Bank) – The dragline begins to swing
before the bucket is disengaged from the
bank.
This practice is where the operator starts the swing process before
disengaging the bucket from the bank.
The bucket is disengaged from the bank by the swing and hoist action.
A skilled operator lifts the bucket as swing is applied and has the
bucket under the boom at all times.
Swinging before disengaging the bucket is a bad habit brought from
the days when swinging hard and fast was taught. It is now known
(through the analysis of duty meter data) that this practice increases
damage to the dragline boom as the bucket is outside the boom plane
and puts torsional (twisting) stresses on the boom.
Dragline Dictionary
T: +61 7 3257 5000
500
Swing Brakes – The holding mechanism
for the swing function
When applied, the swing brakes stop the dragline from turning. The
swing brake should never be applied to slow the machine as it won’t
work and the brake will rapidly overheat.
Swing Brakes
Dragline Dictionary
T: +61 7 3257 5000
501
Swing Dependent – Hoist is slowed to wait
for swing to deliver bucket to dump point
A swing dependent cycle is when the bucket hoisting is slowed to allow
the bucket to swing to the dump point. The bucket effectively reaches
the dump height before the bucket arrives at the dump area.
Swing dependency usually occurs during shallow digging and low
hoisting.
This type of operation would be
swing dependent
Dragline Dictionary
T: +61 7 3257 5000
502
Swing Gearbox – The drive between the
motors and swing rack
The swing gearbox is the drive reduction between the swing motors
and the swing shaft.
Swing Gearboxes
Dragline Dictionary
T: +61 7 3257 5000
503
Swing Motors – Deliver the power that
drives the swing motion
The swing motors drive the swing function that enables the machine to
turn on its axis.
Dragline Dictionary
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504
Swing Pedals – The foot levers that control
the swing function
The swing pedals control the swing function.
When swinging one way the pedals should be reversed to stop the
machine turning and to change swing direction.
These pedals are controlled by the operator’s feet. Pushing the left foot
down enables swing in an anticlockwise direction, while pressing the
right pedal causes the dragline to swing clockwise.
Dragline Dictionary
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505
Swing Pinion – The toothed gear that
meshes into the rack
The swing pinion is located on the bottom end of the swing shaft, and
meshes with the swing rack to turn the dragline.
Swing Pinion
Dragline Dictionary
T: +61 7 3257 5000
506
Swing Rack – A toothed circle that the
swing pinion meshes with to rotate the
dragline
The swing rack is circle of teeth located on the top of the tub. Jutting
out below the revolving frame on the end of the swing shafts are the
swing pinions. The swing pinions mesh with the swing rack and when
power is applied to the swing machinery, the machine rotates.
Swing Rack
Swing Pinion
Dragline Dictionary
T: +61 7 3257 5000
507
Swing Shaft – Large drive shaft between
the gearbox and pinion
The swing shaft is a large diameter shaft that is the drive from the
gearbox on the main machinery deck and extends to the bottom of the
revolving frame.
Dragline Dictionary
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508
Swing Time – The time it takes from the
end of fill time to start of return time
Swing time is the time it takes the dragline to rotate from when the
bucket is disengaged from the bank to the start of the return phase of
the cycle.
Dragline Dictionary
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509
Tail Room – Distance between the rear of
the house and an obstacle
Tail room is the clearance between the rear of the machinery house
and a batter or spoil heap.
It is a good practice for the groundsman to measure the distance so
that the tail of the dragline doesn’t hit the spoil or batter.
Dragline Dictionary
T: +61 7 3257 5000
510
Take a Step (Walk Up on the Block)
Walk up on the block is an expression used when the operator wants to
walk the machine; normally with a small number of steps, when the
dragline walks closer to the area being dug.
Dragline Dictionary
T: +61 7 3257 5000
511
Terrain for draglines (formerly AQUILA™
Dragline System) – Monitor (Caterpillar)
The Terrain for draglines (formerly AQUILA™ Dragline System)
Monitor System combines a centimetre level accurate Real-Time
Kinematic (RTK) Global Positioning System (GPS) with a
comprehensive production monitoring system to provide real-time
geo-referencing of all dragline activities. Right down to the individual
bucket loads and dump locations. Machine performance, productivity,
and payload is monitored and organized in reports to optimize the
dragline output and minimize operating costs.
https://mining.cat.com/terrain-for-draglines
Dragline Dictionary
T: +61 7 3257 5000
512
Throw (or Throw Blast) – Use explosive to
move the overburden towards the
previously mined out strip
Depending on operational requirements throw blasting is used to
move overburden into the old pit void. This can mean that a % of spoil
is moved to spoil and the dragline doesn’t have to move it. This % will
depend on the way the blast pattern is drilled and tied, and the
material being blasted.
Dragline Dictionary
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513
Tight Lining – Occurs when the bucket is
hoisted too close to the boom
Tight-lining is the term given to operating the bucket within the
reference of the tight line envelope. The preferred method of lifting the
bucket is the out and up method. The out and up method doesn’t make
the hoist and drag fight against each other and slow the lifting of the
bucket. It also keeps the bucket away from the boom envelope so the
bucket doesn’t tight line.
When the bucket is in tight line, the hoist and drag functions are
limited and will only operate properly when the bucket is moved away
from the tight line envelope zone.
Skilled operators keep the bucket away from the boom.
Tight line protection is fitted to most dragline booms. It is an
electronic device incorporated with most production monitors, and its
primary function is to prevent the bucket being pulled into the boom.
When the tight line is adjusted correctly, it calculates the amount of
rope on the hoist and drag drums, together with the rope speeds, to
keep the bucket away for the electronic boom envelope.
Tight Line
Envelope
When the
bucket is in this
trajectory, it will
be tight lining
Dragline Dictionary
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514
Toe – The bottom of a batter or face
The toe of an excavation is where the bottom of the batter meets the
floor.
The toe of the cut is an area that the operators need to concentrate on
when digging near the floor as it is easy to leave a couple of metres of
material outside the survey line. A pre-split high wall batter is far
easier the get and keep on line than a normal batter. The dozer has to
clean the coal, so if the toe has been dug properly and to the surveyed
line, there will be a minimum of burden left against the wall.
The spoil toe on the bench is another area that is tidied up by the
dozer.
Low
Wall
Toe
High
Wall
Toe
Spoil
Toe
Dragline Dictionary
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515
Tooth – The cutting tip that is pinned to
the adaptor
The tooth on the dragline bucket is the main cutting edge when digging
the overburden. There are various teeth styles and manufacturers in
the market, so each mine has to pick teeth that meet their
requirements. The teeth are mounted on the adaptors and pinned for
removal as that wear out.
Some mines have the tips of the teeth hard surfaced to get longer wear
out of them and thus lower G.E.T costs.
Dragline
bucket teeth
with hard
surfaces tips
Adaptor
fitted to the
bucket
Tooth fitted to
the adaptor
Dragline Dictionary
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516
Top Dead Centre – Parking position for
shoes
The dragline shoes are parked on Top Dead Centre. There is a gauge
and/or a parking button in the operators cab to assist in parking the
shoes.
There is an electronic/mechanical safety device fitted to the propel
system, so that if the shoes are a couple of degrees off TDC when
parked, swing mode cannot be engaged. This device also stops power
to the swing motion and the swing brakes are applied automatically
should the propel brakes not hold the shoes effectively.
Cam Degrees
Shoe
Park
Note: Cam/shoe position in degrees
during a walk cycle. Shoes parked would
be 0 degrees
Dragline Dictionary
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517
Top Decile – The Best 10% of the draglines
in the world
Top Decile draglines in the world are the top 10% based on production
of machines divided by target suspended load in the PwC database.
PwC has the world’s largest dragline database, consisting of >1,000
dragline/years of production data for comparison. Best practice is
defined as the average of the top decile draglines.
Dragline Dictionary
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518
Top Rail – Part of the bucket structure
The top rail of the bucket is part of the bucket chassis/structure. It is
designed to add strength to the bucket.
Top Rail
Dragline Dictionary
T: +61 7 3257 5000
519
Topsoil – The Dirt on the Surface that
Grows Vegetation
Topsoil is the dirt on the top of the ground that grows the vegetation.
As is a scarce commodity mine sites are committed to saving all of it
for future rehabilitation of the mining areas.
Top soil is stripped and stockpiled ahead of mining operations for later
recovery.
Stockpiled Topsoil
Dragline Dictionary
T: +61 7 3257 5000
520
Total Steel Weight
This is the Total weight of bucket and rigging. Used in the calculation
of payload. The total steel weight is inputted into the monitor
periodically to allow the monitor (which measures actual suspended
load) to calculate payload for each cycle.
Total Steel Weight
=
Bucket Wt + Rigging Wt
The steel weight includes rigging weight as a component of the rigging
but excludes drag and hoist ropes. The weight of the dump rope is
included in the rigging weight.
Dragline Dictionary
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521
Tow Hitch – A device designed to
pull equipment
A tow hitch is designed to tow heavy equipment.
Most mines use a tow hitch to tow the dragline substation, with either
a grader or dozer.
Dragline Dictionary
T: +61 7 3257 5000
522
Trailing Cable – Power cable that brings
power to the dragline
Trailing cable is the power cable that brings the power from the
substation to the dragline. It is moved around as required by
operations.
Trailing cable is in long lengths and joined together by aluminum
plugs.
The trailing cable used and moved more often is the cable between the
dragline and the cable boat. Care needs to be taken in handling the
cable even though it is robust it can and does sustain damage.
Interval view of a typical dragline trailing cable
Trailing cable
Dragline Dictionary
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523
Trainee – Person learning to operate
a machine
A trainee is a person who is learning to operate a machine. They are
also called a novice particularly when first starting. Training dragline
operators is a long and involved process. There are a number of ways
that a mine can train operators.
Most mines use a third party to initiate the training process by having
the proposed trainees attending a week long dragline novice trainee
course that uses a combination of VTS technology, scale and simulated
draglines, sand pit and classroom sessions. They then go back to site
and continue with onsite trainers.
It has been shown and recorded that by using these tools, in a very
short period of time, the trainee then put onto a production machine to
continue training has approximately 55% of his skills, so dragline
production does not suffer dramatically.
It should be understood that a dragline operator will not reach peak
performance until the third year after they finish training. All
operators should continue to learn as long as they are on the dragline.
Scale
Dragline
Scale
Sand
Pit
Dragline Dictionary
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524
Tritronics – A dragline production
monitor manufactured by Leica
Tritronics is a brand name production monitor manufactured by Leica.
The monitor incorporates a GPS system called DragNav, the tight line
software, as well as the production monitor.
Tritronics
Tritronics Monitor
Dragline Dictionary
T: +61 7 3257 5000
525
Truck and Shovel Operations
Truck and Shovel (T & S or T & L) operations are an alternative means
to a dragline for moving overburden in the mining industry. In a
combined operation, T & S will assist the productivity of a dragline,
with one operation complementing the other.
T&S is a more costly process per cubic metre and is around 3-5 times
dearer per cubic metre than a dragline operation, so most operations
optimise the dragline process.
In the smaller mining operations, Truck and Shovel/Excavator is used
extensively as the cost outlay of a dragline cannot be justified.
Typical Large
Scale Truck
and Shovel
Operation
Typical
Smaller Scale
Truck and
Excavator
Operation
Dragline Dictionary
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526
Trunnion – See Hoist Trunnion
The hoist trunnion is where the lower hoist chains are attached to the
bucket. Some trunnions are designed with two holes to enable the
hoist chains to be attached in the front or rear position. These
positions allow a further adjustment for different carry angles and
dump adjustment. The trunnions are normally considered to be part
of the bucket and not the rigging. This should be clarified during the
purchase of a new bucket.
Dragline Dictionary
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527
TSL – Total Suspended Load
Total Suspended Load is the actual suspended load and is the sum of
payload, bucket weight and rigging weight.
TSL = Payload + Bucket Weight + Rigging Weight
The weight of drag and hoist ropes are not included in the calculation
of total suspended load. The weight of the dump rope is included in
the rigging weight.
The total suspended load is what production monitors determine. The
payload is the TSL – bucket weight – rigging weight.
Dragline Dictionary
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528
Tub – The base a dragline sits and rotates
on
The tub of the dragline is the disc that is in contact with the ground
and carries the entire weight of the dragline. It has the house rollers
and swing rack incorporated on the top to allow the dragline to rotate.
The ground work needs to be of a high standard to minimise stresses
associated with uneven ground
Tub being
assembled
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Tub Cable Entry – Where the cable enters
the dragline tub
The cable entry to the tub is designed to allow the cable to enter
without undue stress on the cable.
Dragline Dictionary
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530
Tub Cable Hooks – Brackets that hold the
trailing cable on the tub
The cable hooks on the tub are there to support the trailing cable when
it is wrapped around the tub.
Tub Cable Hooks
Dragline Dictionary
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531
Tub Hooks – Large hooks that help lift the
tub during the walking process
The tub hooks are located at the rear of the dragline house on the area
near each shoe and are used to lift and keep the tub in position when
the machine walks. The Marion and BE machines both have tub hooks,
but P&H draglines uses other means.
Tub hooks
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532
Tub Spin or Slippage – When the tub turns
usually during wet weather
When moisture gets under the tub during inclement weather, the tub
has a tendency to turn. During this time, crews need to be aware as
conditions can be created that may put the dragline in jeopardy. Over
the years, some draglines have had instances when the machines have
slipped off the bench.
If the ground under the tub gets wet and the dragline starts to slip /
spin the dragline should be walked off the pad, the top dozed and the
dragline walked back on.
Dragline Dictionary
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533
Two Way Radio – A Communication
System
Two way radios are used extensively on a mine site. Most dragline
operations have hand held two way radios with a dedicated channel for
the dragline personnel to use for local communication. Some of these
radios are UHF and some VHF. They are a very useful and necessary
means for the crew to keep in contact with each other during
operations. Safety issues were the main drivers to having hand held
radios available to the crew. The communication requirement can be
high and this means of communicating helps facilitate the safe
operation of the dragline..
Portable or Handheld 2 Way Radio
Fixed 2 Way Radio
Dragline Dictionary
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UDD – Universal Dig and Dump
UDD is a concept in digging and dumping. It involves splitting the
hoist drums and controlling them individually. One rope is attached to
the front of the bucket and the other to the rear. This technology allows
the operator to pick up a full bucket and dump it, at a range of points
within the boom plane.
After seven machines were converted between 2002 and 2007 no
further machines have been converted nor new draglines built with
this arrangement.
Dragline Dictionary
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535
Unconventional Bucket – The design of a
bucket that is a different shape to the
perceived norm
An unconventional bucket is the term used for a bucket that is of a
different shape and design than the perceived norm. The perceived
norm is an essentially square or block shape.
The CQMS Scoop, Loadstar and Hurricane are three such buckets that
are classified as unconventional.
In Action
CQMS
Scoop
bucket
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536
Under Swinging – Plugging the machine
before the bucket is in the right position
Under swinging the dragline is as unproductive as over swinging.
Usually, if the machine is plugged before it is in the right position,
power has to be re-applied to the swing and it can create a backlash in
the swing rack and pinion. This does damage the swing system over a
period of time. Also stopping and starting the swing through a cycle
causes damage to the boom structure.
Dragline Dictionary
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537
Undercutting – Digging too close to below
the tub
Undercutting is where the
dragline digs too steep an
angle on the digging face. It is
extremely dangerous with a
significant number of
draglines having slipped into
the pit. The first picture is a
dragline which is in the
process of undercutting the
bench. The dragline pad has
dropped about a meter. The
second photo shows the
outcome of undercutting.
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538
Underhand Chop – When the dragline is
digging a face below the tub line
Underhand chop is when the dragline is sitting on a bench above the
overburden, working below the tub line and digging a face, usually
down and exposing a batter. Chop is distinguished from normal
underhand digging by the bucket starting in a vertical (opening down)
position rather than a horizontal position with the mouth of the bucket
facing the dragline.
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Underhand Digging – Normal digging
below tub level towards the dragline
Underhand digging is when the dragline has its highest productivity.
Underhand is all open faced digging below the tub line.
Under
Hand
Digging
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540
Utilisation – The percentage of the hours
in the day when the dragline is
operational.
Utilisation is reported in %, and is the percentage of operating hours
when the dragline is productively digging.
Dragline Dictionary
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541
Vienna Test System – Measurement of
relevant natural abilities
The Vienna Test System is a computer based testing program
consisting of over 50 tests. These tests assess the perception and coordination abilities required for safe and productive performance of
machinery and vehicle operators. More than 5000 Vienna Test
Systems are in use. Areas of use include; Hospitals, Industrial and
Organizational Psychology, Traffic Psychology, Aviation Psychology,
Universities, Military Psychology, Pharmapsychology, etc.
The Vienna Test System (VTS) consists of powerful basic software and
of the individual tests. Its use is easy and intuitive.
Two-hand coordination test and time movement anticipation test are
the best predictors of dragline operator productivity. These two tests
plus age explain 64% of the variation in operator performance. The
reliability of Two-hand Coordination test and Time Movement
Anticipation test is excellent. Pearson correlation of 0.964 for the two
hand coordination test and 0.970 for time movement anticipation test
have been recorded for dragline operators.
Dragline Dictionary
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542
Visibility – Restricted visibility from the
dragline cab.
Dragline and dozer operators should know what the other is doing at
all times using line-of-sight dedicated communications. This is
difficult as the operator has a very large blind spot area as shown in the
next Figure.
Note: Today electronic camera systems and other proximity warning
devices can reduce these blind spots but usually not completely and as
the operator studies camera screens other hazards can be missed.
Holding a 360 degree view of what is happening near the dragline is a
demanding responsibility and highlights the need for communications
and standard practices that keep the swing radius clear unless
absolutely required for the operation.
Best Practice operations maintain separation between the dragline and
the dozer. The main risks for interaction are hitting the dozer with the
bucket and hitting the dozer with the rear corner of the dragline house.
Most draglines do not allow dozer work in the operating zone of the
dragline and this is certainly the approach taken by the majority of
best practice draglines. Consequently, the operation of the dragline is
limited by the approach to how the dragline working area is set up.
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543
Volume – The Amount of Overburden in a
Given Area
Volume is amount of bank cubic metres, B.C.M. in a given area. Before
digging a pit, mining engineers usually will work out the volume of
overburden bcm to be removed from the pit area. The production
monitors on the dragline record the volumes of overburden removed,
bucket by bucket, and on a regular basis, reports are printed to keep
track of how productive the dragline is. Survey will, on a regular basis;
reconcile the volumes of material removed against the production
monitors.
Dragline Dictionary
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544
VR Steel – Van Reenen Steel
A Dragline Bucket Manufacturer based in South Africa.
http://www.vrsteel.co.za/
Dragline Dictionary
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545
Vulcan – Dragline Module (Maptek)
The Vulcan Dragline Module offers a powerful set of mine planning
tools for the creation; manipulation and reporting of section-based
range diagrams.
http://www.vulcan3d.com/e_dragline.html
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546
Walk Road – Roadway for the dragline to
walk from one working area to another
A walk road is a road designed and constructed to a standard that
allows the dragline to walk safely and effectively from one pit to
another. The design of the walk road will vary as each machine is of
different sizes, and the road should be constructed to accommodate
the width of the machine plus room for cable and cable boat access,
and enough room outside of that to have access around the for vehicle
access should it be required. Also when a walk road is through a
cutting or a ramp, consideration should be given to rear of the machine
room if it has to maneuver.
All soft areas in the walk area should be dug out and backfilled with
competent material. While the machine is walking, consideration
should be given to having a water truck flood the walk road so the tub
slides easier on the ground and thus, putting less strain on the propel
train. This is more important in hot weather.
Walk road
Walk road
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Walk Time – A delay recorded while
moving the dragline from one position to
another
During the dragline digging process, the machine has to be positioned
regularly. To get into position the dragline walks, and the time taken to
achieve this is walk time. The production monitors record this time
automatically when the operator engages propel mode.
There are significant losses associated with walking mostly during the
set up and finish of the walk event (~200 seconds average loss). These
losses are usually a function of poor procedures and or equipment.
There is also an average loss of 8 seconds per step.
Average Walk
Best Walk
2000
1800
1600
Seconds
1400
1200
1000
800
600
400
200
0
0
5
10
15
20
25
30
No. of Steps
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Walk Ways – Access for personnel on the
dragline
There are many areas that have walk ways in and around a dragline.
Walk ways make a safe access for personnel to get to the different
areas of the machine. To name a few, the boom and mast have walk
ways for access also in and around the machinery house.
Boom Walk Ways
Walk Ways around the
House
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Walking (Deadheading) – Also called a
“Long Walk”
Deadheading is normally described as movement from the end of one
strip to the start of the next strip.
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Walking (Positioning/Maneuvering)
Draglines move by “Walking” this is effected by propel motors rotating
a cam which lifts the machine onto two shoes and then over to a new
position approximately 2m ahead.
Positioning/Maneuvering is normally described as movement within a
strip.
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Walking Shoes – The pads that support the
weight of the dragline while walking
The walking shoes are attached to the cam and carry the weight of the
dragline while taking a step. The shoes are sometimes called paddles
or pontoons. The shoes are approximately 3/4 of the length of the
machine house and the width can be up to 5 metres, depending on
machine size. Ground work needs to be of a high standard, as the shoes
cover a large area, and if not level, the shoe can sustain damage if it is
not supported underneath. Also large rocks at the surface of the pad
can damage the soles of the shoes.
Changes in gradient of the dragline walk road are stressful on the
shoes and have caused the shoes to break.
Walking
Shoes
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552
Wedge – Locks the ropes into the socket
A wedge is used with a socket and locks the ropes into the socket. All
the ropes terminate at the sockets. A loop of rope is created in the
socket, and the wedge is inserted in the loop. When the rope is
tightened, it pulls and locks the wedge in and holds the ropes in place.
Socket
Wedge
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553
Wire rope – Consists of several strands
laid together like a helix
Wire rope consists of several strands laid (or 'twisted') together like a
helix. Each strand is likewise made of metal wires laid together like a
helix. Initially wrought iron wires were used, but today steel is the
main material used for wire ropes.
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554
Witches Hats – Reflective safety cones
for demarcation of working areas
Witches hats are used extensively around a mine site. Around a
dragline they mark the cable, parking areas, and anywhere that
identification is required.
Witches Hats
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Working Area – Dragline boom radius
area
The working area of the dragline is an area defined by the boom point
radius. It may be just inside the arc formed by the vertical line down
from boom point or it may be a defined distance outside this line.
Each person should make it their business to find out what it is for
their site.
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556
Wraps – The number of times the ropes go
around the drum
The wraps on the drum changes as the ropes are payed out and reeled
in. There is a minimum number of 2.5 wraps required on the drum
when on the payout limits. This is so no strain comes onto the drum
rope bolts when engaging the bucket and applying power.
7 Wraps on Drum
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The publishers of the Dragline Dictionary have exercised the utmost care in the composition of this
publication; however, PricewaterhouseCoopers cannot be held responsible for errors, inaccuracies,
or omissions resulting from the nature of the information provided or previously published, or through
typographical compilation.
© 2014 PricewaterhouseCoopers, ABN 52 780 433 757. All rights reserved. PwC refers to the
Australian member firm, and may sometimes refer to the PwC network. Each member firm is a
separate legal entity. Please see www.pwc.com/structure for further details.

Dragline Dictionary

Transcription

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