The application of smoothed particle hydrodynamics to the simulation of multiphase flows through packed beds

Abstract

Heap leaching is an important hydrometallurgical minerals processing technique, which involves the irrigation of leaching solution through a packed bed of ore particles. It is a complex process governed by the precise chemistry of the ores and leaching solution, the biological action of bacteria that live on the rocks, and the multiphase fluid flow through and around the rocks. In order to improve the predication of recovery and the performance of the operations, a better understanding of all aspects is vital. Several studies have suggested the importance of the fluid flow and mass transport within the heaps. The smoothed particle hydrodynamics (SPH) method has a proven track record of simulating saturated flows at very small scales for porous media and is a natural tool for gaining an insight into the flows within packed beds. In this thesis we present developments to the handling of wall boundaries in SPH with an aim towards handling arbitrary geometries and improving accuracy. As well as considering the inclusion of surface tension and contact angles for simulating unsaturated flows. A volume factor correction for curved boundaries is developed that demonstrably improves accuracy of simulations, as well as detailing a ‘boundary integral method’ for including wall boundaries. The developed SPH simulation code is used to run a variety of unsteady unsaturated simulations through 2D packed beds, including the effects of molecular diffusion. These simulations demonstrate the important roles that saturation and capillarity play in packed beds, with unsaturated flows having enhanced transport coefficients as compared to higher saturations. These simulations also serve to highlight the fact that even at relatively long time scales, from the perspective of the flow, that the transport is not in the simple Fickian regime, which is often used when modelling heaps and other packed beds at a larger scale.