Challenges in developing polymer flocculants to improve bitumen quality in non-aqueous extraction processes: an experimental study

Western Canada's oil sands hold the third-largest hydrocarbon deposits in the world. Bitumen, a very heavy petroleum, is currently recovered by surface mining with warm water or in situ. Recovery processes that use organic solvents are being developed to reduce water usage and tailings production. While solvent-based methods can effectively extract bitumen, removal of residual fine solids from diluted bitumen product (DBP) to meet the pipeline transport requirement of < 0.5 wt% solids and water in DBP remains a major challenge. We propose a novel area of application of polymer flocculants for fine solids removal from DBP. In principle, polymer flocculants can be applied to help remove these residual solids in conjunction with physical separation processes to increase process effectiveness and energy efficiency. Several polymers are selected and screened for flocculation behavior using kaolinite suspended in DBP and toluene, as a model system. Focused beam reflectance measurements and force tensiometer techniques are used to determine flocculation and sedimentation in DBP. The observed flocculation and sedimentation rate enhancements indicate that the polymers tested have only minor effects, providing opportunities for advanced polymer development. These findings exemplify the challenges in identifying polymers that may be effective as flocculants in heavy petroleum media.