Electrokinetic Dewatering of Oil Sands Tailings

Oil sands tailings are the final product of oil sands processing and in the form of slurry with very low solid content. After sedimentation, due to a low hydraulic conductivity of the tailings, both dewatering and consolidating the tailings are difficult. Since electrokinetic (EK) is an effective method to consolidate low permeability soils, the objective of this study is to assess the effectiveness and efficiency of EK dewatering of MFT, a man-made geomaterial. Two series of tests were conducted in this study. In the first series, four EK cell tests were performed on oil sands tailings to measure the electroosmotic permeability, ke, along with other parameters, such as the EK induced water flow rate, electrical conductivity of the tailings, and power consumptions. The second test series was the dewatering model tests to investigate the feasibility of EK dewatering on oil sands tailings. The performance of the EK dewatering under two conditions was compared, i.e., 5 kPa consolidation at first followed by EK dewatering; and 5 kPa consolidation and EK dewatering simultaneously. The final water content, undrained shear strength and plasticity properties of MFT were measured after the EK dewatering tests. After the EK dewatering model tests, a significant overall increase in the undrained shear strength and decrease in the water content of tailings samples are observed, along with significant changes of the plasticity.