SHELL ALBIAN SANDS

SHELL ALBIAN
SANDS
OVERVIEW OF
TAILINGS AND SHELL
TECHONOLOGIES
WHAT ARE TAILINGS?
Oil Sands are a mixture
With the bitumen removed, a mixture
of bitumen, sand, silt and
of water, small amounts of residual
clay materials.
bitumen, sand, clay particles, small
Once excavated, the oil sands go
through an extraction process where
warm water is added to wash the
bitumen off the sand. Once the sand
fines particles and other solids are left.
The combination is often referred to as
‘tailings’, and they can be found across
a number of different mining industries.
and other particles are removed the
bitumen is transported for upgrading
and will eventually be used as a source
of energy.
Illustration showing the flow of the extraction process
OIL SANDS EXTRACTION AT SHELL ALBIAN SANDS
1
‘Tailings’ can be found
across a number of
different mining industries.
2
WHAT ARE
TAILINGS PONDS?
WHAT ARE TAILINGS
PONDS USED FOR?
The pipeline carrying the tailings
flow down the dyke walls and into the
Once the tailings have reached
The water that rises to the top is then
runs to a constructed dyke or
tailings area. The sand and a lot of
the tailings pond a few things
recycled back into the plant for the
mined out area of the pit which
small particles contained in the tailings
happen. First, any sand and some of
extraction process. The ponds serve an
resembles a pond. Once the
settles along the dyke walls. Forty to
the small clay particles not captured on
important purpose as they allow the water
tailings are released within the dyke,
50 per cent of the small fines particles
the dykes start to settle to the bottom of
to be re-used, reducing the need for
most of the water and lighter materials
are also captured here.
the pond and water rises to the top. The
fresh water. Shell recycles about
rest stay suspended in the water.
80 per cent of the water used in our
mining operations.
40-50%
OF THE SMALL
PARTICLES ARE
CAPTURED ON
THE DYKE WALLS
Cut-through illustration showing
a tailings pond
DEPOSIT OF TAILINGS SAND
AT SHELL ALBIAN SANDS
3
Sand contained
in the tailings
settles along
the dyke walls.
The ponds serve
an important
purpose as they
allow the water
to be re-used.
80% OF THE WATER
IS RECYCLED
Illustration showing the flow of water
through the mine
4
WHAT HAPPENS
ONCE THE TAILINGS
HAVE SETTLED?
Once all the material in the
vegetation, trees and shrubs. The
ponds has had time to settle, the
quicker the tailings materials settle,
process of reclamation begins;
the faster these tailings areas can be
placing topsoil and then planting
transformed into reclaimed land.
TAILINGS
BEFORE
1
Over time sand, silt, and clay
settle to the bottom of the pond.
2
Water is removed for use in the
extraction process.
TAILINGS
AFTER
3
Overburden and top soil are
replaced back into the tailing
pond.
4
Native vegetation is reintroduced
to the site.
5
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WHY ARE PEOPLE
CONCERNED ABOUT
TAILINGS?
BIRD DETERRENT SYSTEMS
AT SHELL ALBIAN SANDS
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Concerns around tailing are focused
around the amount of space
the ponds take up, the potential
threats to wildlife, and the time
it takes for the areas to be reclaimed.
WHY ARE TAILINGS
PONDS SO BIG?
Due to the volume of water,
areas of the mine. These are called
external tailings ponds occupy a
‘In-Pit’ tailings. Most operators are now
fair amount of land. To help reduce
able to use In-Pit tailings areas to reduce
the amount of land needed, once
their land footprint. At Shell we have
mining is sufficiently advanced, tailings
one tailings pond for the Muskeg River
are placed in previously excavated
Mine and one for the Jackpine Mine.
Tailings are placed
in previously
excavated areas
of the mine.
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ARE TAILINGS PONDS
A RISK TO WILDLIFE?
WHY DOES IT TAKE
SO LONG TO RECLAIM
A TAILINGS POND?
Tailings can contain small amounts
animals if they try to land on them.
Reducing the amount of these
MFT, are not heavy enough to settle
of unrecovered bitumen, which
Oil sands operators spend millions of
fluid fines has therefore become
to the bottom of the pond, and lie
sometimes form small patches
dollars on world class wildlife deterrent
one of the biggest challenges
suspended in the water for many years.
on the surface of the ponds.
systems to minimize harm to animals
for the industry – accelerating
Because of this we call them ‘fluid fines’.
The pond’s surface area is mostly water –
in the area. Our bird deterrent systems
their drying time means we can
Without assistance, these fluid fines
just the areas at the edges can be
have ensured that, very few birds have
reclaim the tailings areas faster.
would take many years to consolidate.
prone to this bitumen. These patches
landed in our tailings ponds.
The very small fines particles often
can be a danger to birds and other
referred to as ‘Mature Fine Tails’ or
25
Illustration of bird deterrent system
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Reclaimed Land
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WHAT IS SHELL DOING
TO SPEED UP THE PROCESS
OF RECLAMATION?
WHAT IS
BEACHING?
Over the last 10 years, Shell
Key technologies we are currently
When tailings come out of
are captured during beaching. At our
has spent over $200 million
working on include: Beaching,
extraction and enter the ponds,
Muskeg River Mine, through technology
on tailings technology
Atmospheric Fines Drying and,
most of the sand and a portion
application even more of these fines
and research.
Thickened Tailings.
of the fines are captured in the
have been captured – up to 65 per cent.
dykes and beaches. The more fines
Shell believes it is very important to
captured here, the better; as it reduces
continue trying to capture more fines
the amount of fines that become ‘fluid’.
at this stage and stop them from ever
Fourty to 50 per cent of these fines
becoming fluid.
65%
50%
Xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
ATMOSPHERIC FINES
DRYING (AFD)
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Shell has spent over
$200 million on
tailings technology
and research.
A TRUCK DRIVES ON THE SAND
CONTAINED IN TAILINGS DYKE.
12
WHAT IS ATMOSPHERIC
FINES DRYING?
Atmospheric Fines Drying or AFD focuses on drying the fluid fines more quickly.
1
A dredge sits in the middle of
the tailings pond, and draws
the fluid fines out.They are then
transported to a drying area.
2
Before they are placed in the
drying area, the fines are mixed
with a ‘flocculent’ or thickener,
which helps bind them together,
into larger particles.
3
This thickened MFT is then spread
in thin layers over the drying area.
Because the fines are now more
tightly bound, the water separates
from the fines and drains off the
surface.
Once the fines have dried completely, further layers are placed on top.
This approach results in the fines drying in a matter of weeks, rather than years.
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This approach
results in the fines drying
in a matter of
weeks.
14
WHAT ARE
THICKENED TAILINGS?
Thickened tailings or TT is currently used exclusively by Shell. After extraction, instead of
the tailings going straight to the tailings area, they go to a thickening plant.
1
At the thickening plant, a flocculent
or thickener is added to bind the
particles together before they
reach the tailings pond.
2
The design means a significant
amount of the water is drained
off at the plant, so that it can
be recycled straight back into
production. Because the water we
drain off is still warm it does not
need to be re-heated to the same
degree as normal tailings water,
when it re-enters production. This
means we save energy.
3
Without the water, and with the
addition of the flocculent, the tailings
are much thicker as they travel to
a dedicated disposal area. Here
they are again spread in layers,
and allowed to consolidate.
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Because the water we
drain off is still warm
it does not need to
be re-heated to
the same degree,
therefore saving energy.
16
All photos taken at Albian Sands,
Athabasca Oil Sands Project, Canada 2011
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796595–PCOEL–08/2012