Surface Mining and Extraction of Oil Sands
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Another major resource in Alberta is the oilsands. This tar-like form of oil known as
bitumen, is removed
from a mixture of sand and clay. Shallow deposits of bitumen are
mined from the surface and deeper deposits are recovered through
wells. Once the bitumen is extracted, tailings are left
behind. The tailings are a slurry - a mixture of water and solids,
containing sand, silt, clay and unextracted bitumen. The slurry is
discharged into tailings ponds. The sand rapidly settles out and
is used to build dykes around the ponds. Some of the clay
particles remain suspended in the water and form what is called fine
tailings. The solids in the fine tailings do not settle out for
many years. Research into the reclamation of these fine tailings
continues today.