Dewatering kinetics and viscoelastic properties of kaolin as tailings model under compressive pressures

Reclaiming solids and water from underflow discharged into tailings ponds is important for environmental sustainability in bitumen recovery from oil sands by hot water processes. Difficult-to-separate networked structures of fine tailings concentrates require process aids as well as an understanding of the material properties and behaviors in flow induced by imposed pressures. This paper examines the viscoelastic properties of a model kaolin slurried in model process water (MPW+), for a total ≈12.1%v/v solids. By using the Anton Paar MCR301 Immobilization Cell (IMC), the kaolin slurry was dewatered by varied stepped-up suction pressures. For each pressure step, as water was expelled through the porous sediment and filter media, the dynamic oscillatory rheological properties were measured. Complex viscoelastic modulus G*, the storage (elastic) modulus G′ and viscous modulus G″, as well as absolute complex viscosity | η * | , increased as a function of dewatering time, volume fractions of solids and suction pressures. Compressive yield stress plotted as a function of equilibrium solids volume fractions compared closely along data obtained earlier using a LUMiFuge. A scaling law function described the overall behavior for these data lumped with data obtained earlier using a pressure filtration rig.