Rapid Dewatering and Consolidation of Concentrated Colloidal Suspensions: Mature Fine Tailings via Self-Healing Composite Hydrogel.

Abstract

Billions of tonnes of thick waste streams with highly concentrated colloidal suspensions from different origins have accumulated worldwide, exampled as over 220 km2 mature fine tailings (MFT) from oil sands production in north Alberta. Current treatment technologies are limited by slow yet insufficient water release and sludge consolidation. Herein, a self-healing composite hydrogel system is designed to convert concentrated aqueous colloidal suspensions (e.g., MFT with colloidal solid content >30 wt %) into a dynamic double cross-linked network for rapid dewatering and consolidation. The resultant composite hydrogel demonstrates an excellent dewatering performance so that over 50% of water could be rapidly released within 30 min by vacuum filtration. Furthermore, the formed infinite cross-linked network with self-healing ability can effectively trap fine particles of all sizes and capture small flocs during mechanical mixing, thereby enabling a low solid content at the ppm level in the released water. This new strategy outperforms all the previously reported treatment methods; under mechanical compression, over 80% of water is removed from the MFT, thereby generating a stackable material with >70 wt % solids within an hour. These results demonstrate a highly effective approach and provide insight into the development of advanced materials to tackle the challenging environmental slurry issues.