Centrifuge dewatering of polymer-amended oil sand tailings

The main objective of this paper is to understand the process of centrifuge dewatering of polymer-amended mature fine tailings. Laboratory investigations indicated that dewatering improves up to 600 g (because of assemblage formation due to increased particle collisions and polymer adsorption) beyond which dewatering declines (owing to floc breakage due to excess centrifugation and surface saturation). For 10 mg/L polymer, the released water increased to 17%, the entrapped water decreased to 42%, and the sediment solids content increased to 42%. The corresponding values at 20 mg/L were found to be 34%, 18% and 47%, respectively. Likewise, the physicochemical parameters were found to correlate well with tailings dewatering. The decrease in pH, electrical conductivity (EC) and zeta potential (ZP) up to 600 g is due to water dilution, charge neutralisation and shear plane displacement beyond which opposite phenomena occurred. At the optimum and 10 mg/L polymer, the pH value decreased to 7·5, EC decreased to 2615 µs/cm, and ZP decreased to −26 mV. The corresponding values at 20 mg/L were found to be 7·5, 2234 µs/cm and −21 mV, respectively.