Methods are provided for treating intimately dispersed mixtures of water, bitumen, and fine clay particles, such as oil sands mature fine tailings (MFT). Select methods use dissolved silicate ions and a base (alkali), optionally in combination with a biopolymer, to flocculate a slurry. A mixing regime is disclosed involving the addition to MFT of silicate ions in solution and alkali, to initiate aggregation/destabilization of clay particles. Methods are exemplified that provide distinct sediment layers in conjunction with the release of residual bitumen (for example 40-50% of the initial bitumen content). In these exemplified embodiments, a densely packed bottom layer containing ˜75 wt. % solids showed high yield stress values (3.5-5.5 kPa) and entrapped little residual bitumen (0.2-0.3 wt. %). The methods accordingly segregate a material suitable for reclamation.