Oil sand tailings characterisation for centrifuge dewatering

Abstract

The main objective of this paper was to develop a fundamental understanding of oil sand tailings for centrifuge dewatering. Laboratory characterisation indicated that the investigated tailings were a fine-grained material (53% clay fraction) with a moderate water adsorption capacity (ωl = 55% and ωp = 25%). The solids consisted of 55% quartz and 40% clay minerals and showed a specific surface area of 43 m2/g and a cation exchange capacity of 29 cmol(+)/kg. Likewise, the pore water (pH = 8·15, EC = 3280 µS/cm and ZP = −46 mV) was dominated by Na+ (776 mg/L), [Formula: see text] (679 mg/L), Cl− (518 mg/L) and [Formula: see text](377 mg/L). Centrifugation physically improved tailings dewatering through particle segregation, assemblage formation and flow channeling. For a g factor of up to 2550 g, the released water increased by 4·7%, the entrapped water decreased by 30% and the sediment solids content increased by 7%: all quantities compared to self-weight settling. The corresponding decrease in physicochemical properties confirmed aggregate formation and an effective capture of clay particles in the suspension zone.