Thickening and disposal of fine tails from oil sand processing

Syncrude and CANMET have jointly developed a new technology for the disposal of fine tails from oil sand processing. A high molecular weight, medium charge, anionic polymer is used to flocculate and rapidly settle fine solid particles in a high rate thickener, to a paste-like consistency of 50 to 65 % solids concentration by weight. The released turbid warm water is recycled for reuse in the bitumen extraction process. The paste is pumped to the disposal areas, either in or out of the mined-out pit. Here, the discharged paste forms a gently sloping deposit. The slope allows the released water to run off, promoting the consolidation of the deposit through gravity drainage, surface desiccation and natural freeze-thaw cycles. Partially consolidated paste deposit can be hydraulically capped with tailing sand and incorporated within the coarse tailing beach. This paper presents the results of an extensive technical program, involving flocculant selection, continuous thickener pilot operation, paste pipelining and evaluation of geotechnical properties of the paste deposit.