Processing of tailings in Canadian oil sands industry

Vast amounts of tailings are produced daily in bitumen extraction from the Athabasca oil sands. The coarse sand from the tailings stream is used to build dykes around the containment basin. The run-off slurry arrives at the water's edge in the tailings pond at a solids concentration of about 3%～8% by mass. Settling of the solids takes place "relatively fast", over several days, creating a "free water zone" that contains little solids. When the fine mineral solids concentration has reached about 15% by mass, the suspension develops non-Newtonian properties. After 2～3 years, the suspension concentration reaches a value of about 30% by mass at which the settling rate becomes extremely slow. Methods to handle the already created tailings ponds and new approaches to eliminate the creation of new ones will be discussed both from the industrial and fundamental prospective.