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

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.