Dewatering Oil Sands Fluid Fine Tailings by Enhanced Flocculation Chemistry and Volute Screw Press

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Rapid dewatering technology of Alberta oil sands tailings is urgently needed but currently unavailable. Rapid dewatering enables fast recycling of the warm process water and the generation of stackable reclamation-ready tailings. Such a technology can eliminate the need for large tailings ponds, significantly lower fresh water consumption, and lower energy consumption and GHG emissions associated with heating the fresh water to about 50°C. Through a preliminary test program sponsored by Imperial Oil, we have recently demonstrated the success of dewatering oil sands fluid fine tailings (FFT, 21 wt% solids, sand-to-fine ratio (SFR) of 1.0) by a combination of low-dosage chemical amendment and Volute screw press treatment. For instance, the chemical-amended FFTs were fed to the Volute screw press at up to 14.3 kg-dry solids/h throughput, yielding 65-72 wt% solids in the discharge cakes continuously and consistently and 0.2 wt% solids in the filtrate (i.e., process water). The results exceeded the current target solids content to dewater FFT (i.e., 60 wt%) in the oil sands industry, while the filtrate from the Volute screw press can be reused directly with no further treatment in oil sands extraction process.The current proposal is a continuation of the research. In the proposed project, we will evaluate the application and commercial potential of enhanced coagulant-flocculant chemistry plus Volute screw press on a range of oil sands tailings including fluid fine tailings (FFTs) with different SFRs and solids contents, thickened tailings (TT), and tailings-solvent-recovery-unit (TSRU) tailings. The results and knowledge obtained from this project will position the proposed Volute screw press technology in line with Alberta Energy Regulator's Directive 085, resulting in a rapid dewatering technology for the Alberta oil sands tailings.