Electrophoresis and its applications in oil sand tailings management

Abstract

Oil sands mines generate tailings during the extraction process, which are a mixture of water, clay, sand and residual bitumen. When the tailings are released to tailings ponds, the coarse solids settle quickly, whereas fine solids containing clay minerals, namely mature fine tailings (MFT), remain suspended for years, even decades. A study is carried out to assess the suitability of electrokinetic (EK) sedimentation to accelerate sedimentation of MFT. A series of laboratory-scale column experiments are carried out to examine the effects of electrophoresis during settling processes. The investigation focuses on the effects of EK sedimentation as related to the initial solid content of the tailings suspension, applied electric field intensity, water pH, and the use of an optimized coagulant FeCl3. Based on the experimental data, an electric field intensity of 150V/m along with an initial tailings solid content of no >5% are the optimum condition for EK sedimentation of MFT, in terms of reducing the overall sedimentation time and increasing the final solid content. The results show that the current density of EK sedimentation for MFT should not be >20A/m2 to control the bubble effect and reduce power consumption.