CFD MODELING AND COMPARISON WITH EXPERIMENTAL RESIDENCE TIME DISTRIBUTIONS IN SINGLE AND TWO PHASE POROUS FLOWS

Metals extraction using heap-leaching methods is very slow particularly for sulphide ores, but the pathway to faster leaching is not obvious because of the complex and poorly understood chemistry and hydrodynamics involved. Computational Fluid Dynamics (CFD) has the potential to assist by improving understanding of the interaction between hydrodynamics and chemistry. Before CFD modelling can be used to assist heap design and optimisation the model should be validated. This paper describes model validation using experimental columns loaded with porous media. A commercial CFD code (CFX4.4) was used to model the flow of single liquid phase and two-phase gas liquid counter flow, in a column of porous media. A passive tracer was used to determine the liquid residence time distribution curves in the columns and simulations were validated using the experimental test results. The liquid movement was modelled by dividing it into two components: flowing and stagnant. This work will show the effect of the ‘stagnant liquid volume’ on the tracer breakthrough profiles leaving the computational geometry. The CFD predictions were found to be in good agreement with experimental data. In further work the CFD models will be expanded to include other phenomena associated with mineral extraction leaching, leading to the full modelling of an operating heap.