Removal of bitumen from mature oil sands tailings slurries by electro-flotation

The separation of bitumen from mature oil sand tailings slurries was carried out in an electro-flotation (EF) cell equipped with titanium coated with iridium oxide (Ti-IrO2) mesh as anode and stainless steel (SS 316) mesh as cathode. The effects of operating parameters such as pH, current density, bitumen concentration, and sodium chloride (NaCl) dosage on the performance of batch cell flotation were examined. The representative kinetics of the electro-flotation of bitumen in mature oil sand tailings slurries is best described as a first order reaction. Analysis of variance (ANOVA) is carried out to find out the statistical significance of influencing factors with respect to the first order flotation rate. The P-values in ANOVA show the order of significant factors as current density > bitumen concentration > pH. Though NaCl dosage doesn't have significant effect on flotation kinetics however it serves a significant role on reducing the power consumption of EF treatment. It is observed that at current density 150 A/m2, it is possible to reduce the bitumen concentration from 106.8 mg/L to less than 10 mg/L within 90 min of flotation to meet the Environmental Protection and Enhancement Act (EPEA) maximum discharge limit.