Evaluation of candidate polymers to maximize geotechnical performance of oil sands tailings

Abstract

Oil sands fluid fine tailings deposits are challenging to reclaim due to their inherently high natural water content, low permeability, and low strength. Combinations of polymers and (or) coagulants are used by operators to improve the dewatering and strength properties of the tailings. However, considerably more work has been done to evaluate polymer performance with short-term dewatering metrics rather than with long-term metrics such as consolidation properties. This paper evaluates the potential of four novel polymers for use in fluid fine tailings treatment compared to a commercially available polymer and untreated tailings specimen. The performance of the polymers was assessed through initial screening with respect to short-term dewatering, evaluation of the consolidation and strength properties using large-strain consolidation tests, shear sensitivity in pipeline transport, and finally, large-strain consolidation modelling to appraise the relative potential performance under different strategies, such as terrestrial or aquatic reclamation options. One polymer exhibits remarkably fast dewatering at high void ratios, while another demonstrates dense and shear-resistant flocs. The paper discusses each polymer’s distinctive tailings fabrics and how their unique merits and limitations would benefit different reclamation eventualities. Finally, potential improvements of the polymers are suggested for future assessment.