Stabilization of oil sands tailings using vacuum consolidation

This research is an experimental design and numerical analysis of a novel technique of the vacuum consolidation of Mature Fine Tailings (MFT). A meso-scale test was conducted to examine the feasibility of the MFT dewatering process. Vacuum consolidation involves applying a negative water pressure to the coke layer overlain by a saturated sand layer and underlain by MFT. Numerical modeling was conducted using the finite element program SoilVision to model the meso-scale experiment. Unsaturated behavior of Suncor coke, Suncor sand and MFT was investigated using Tempe pressure cell and capillary rise in an open tube prior to commencement of tests. Results indicate that a flux of water flows from the MFT layer into the coke layer which is indicative of the MFT dewatering. The modeling analysis indicates that suction has little effect on the settlement while the overburden has the significant effect on consolidation. This thesis also illustrates the importance of recalibrating TDR probes for different materials. The three layered system testing of MFT, Suncor coke and Suncor sand indicates that applying suction causing MFT to dewater, can set the stage for a four layered system in which another layer of MFT is placed on top of the sand layer. The suction applied to the coke layer causes the double-drained MFT to dewater faster.