Modelling of thixotropic behaviour of oil sand tailings during withdrawal

A mathematical model for fluid fine tailings withdrawal from a pond is developed and adjusted based on the rheological experiments of structure breakdown and buildup. The model includes thixotropic effects for the viscoplastic fluid and is coupled with the Navier–Stokes equations to simulate the motion of the slurry during a transient dredging process. Laboratory scale experiments to withdraw tailings from a small cylindrical vessel were carried out in the lab to facilitate model validation. The comparison of the evolution of the free surface height demonstrated good agreement between the measured and predicted profiles. The model provides insights into the tailings withdrawal process and highlights the thixotropy effect in changing the rheology of the tailings. The modelling can be utilized to support development of efficient mitigation techniques that would help to optimize tailings withdrawal strategy from a pond.