Water‐soluble polymers for oil sands tailing treatment: A Review

Abstract

Efficient dewatering of oil sands tailings is imperative to reduce the environmental footprint of oil sands operators. Currently there is no mature technology capable of effectively treating oil sands tailings and completely eliminating the use of tailings ponds. Consolidated tailings and paste technology are the most extensively used dewatering methods. However, the high concentrations of divalent ions in the water recovered using the consolidated tailings process impedes the re‐utilization of this water in the bitumen extraction process. Accumulation of ions does not occur in the case of paste technology; however, this technology, similarly to the consolidated tailings process, recovers only part of the water from tailings and produces high‐water content sediments (25–30 wt. % solids) that sill requires special storage. This happens because the sediments produced by polyacrylamide (PAM) flocculants are not closely packed and require the application of other consolidation technologies (e.g., freeze‐thaw, filtration, centrifugation) to obtain dry and self‐supportive tailings. This review focuses on examining alternative flocculants that could potentially replace PAM polymers in mature and new dewatering technologies. Flocculants are a key element of many tailing treatments including paste technology and filtration. The “ideal” flocculant would increase the ability of these technologies to dewater tailings, resulting in higher water recovery and sediment consolidation without affecting water chemistry or increasing operational costs. This review presents a comparison between PAM flocculants and two promising alternative flocculants: inorganic‐organic hybrid and temperature‐sensitive polymers. Each flocculant type is evaluated in terms of its flocculation mechanisms and its dewatering efficacy.