Polymeric flocculation of oil sands tailings: Unveiling rheological indicators and dynamics of bitumen release

Abstract

Polymeric flocculation is widely used to accelerate the dewatering and consolidation of oil sands fluid fine tailings (FFTs). Optimizing flocculation requires a fundamental understanding of the changes to the internal structure of the material with polymer addition. Key challenges include sensitivity of flocculation to polymer dose, mixing conditions, and composition of individual FFTs. Moreover, despite the environmental implications, little is known of the effects of flocculation on the mobility of the residual organics present in the tailings. In this paper, advanced rheological tests are used to probe the formation and development of the polymer–clay structure during flocculation in near-real time. This is achieved through a novel setup for controlled delivery of the polymer directly into the measuring cell of a rheometer. This enables continuous monitoring of the rheological parameters during the flocculation process and yields consistent and reproducible samples. An optical monitoring system is used to relate rheological measurements to water release and to changes in the surface accumulation of the residual bitumen. The water-release polymer dose is found to be associated with a distinct rheological response highlighting the potential use of rheometry for polymer dosing/mixing optimization in real time and on a continuous basis in thickeners and inline flocculation systems.