Fundamental Studies in Solid-Liquid Separation in Oil Sands

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This proposed project aims at studying the fundamental colloidal science issues in two prominent solid-liquid separation problems in oil sands industry. These are the dewatering and consolidation of the oil sands tailings (solid-water separation), and the removal of fine mineral solids from product bitumen of a nonaqueous extraction (NAE) process (solid-solvent separation). In the former the emphasis is on the role of residual bitumen, a mobile and deformable 3rd phase, and the clay surface wettability caused by adsorbed bitumen and polymers on tailings dewatering, as well as the effects of polymer and surfactant additives on the bitumen and the resulting effect on dewatering. In the latter, the emphasis is on the interactions of insoluble bitumen components and suspended minerals, and the resulting colloidal forces in the nonaqueous organic solvent suspension under NAE conditions. The importance of this research is seen from the ultimate targets of the two solid-liquid separation problems. In the tailings case, the aqueous slurry (mature fine tailings) usually contains 30-40 wt% solids and the target is to increase it to >=75 wt% ready for reclamation. In the NAE case, the organic solvent suspension usually contains low concentrations of mineral solids but the target is to lower it further to <=0.03 wt% solids so that it can potentially be used as a feed to refineries without the need of an upgrader (which is capital and operating cost intensive and energy intensive). Both targets are extremely challenging to achieve. It is anticipated that the proposed 5-year Discovery Grant project can provide insights to the reasons to the difficulties and thus point to mitigation measures. The solutions will ultimately benefit the oil sands industry of Alberta and Canada, leading to processes that more responsibly utilize the oil sands resources. The research will also contribute to the scientific literature on solid-liquid separation in the presence of insoluble and deformable materials such as bitumen. The project will also provide an opportunity to train highly qualified personnel for the Canadian economy and society.