Investigation of Hydrodynamic Flow in Heap Leaching Using a CFD Computational Model

Heap leach processes can encounter diverse flow conditions, such as infiltration into dry ore material, drainage, perched water tables and heterogeneous materials, leading to large variations in permeability and the creation of preferential flow pathways. Climate and meteorological conditions, such as precipitation, evaporation, and temperature, can also have a significant effect on the hydrodynamics of the heap. Nonuniform and adverse flow behavior within the heap contributes to reducing the leaching efficiency of the heap leading to lower metal recoveries. The variability of flow within the heap can result in solute transport problems, which limit the leach reaction kinetics. Therefore, understanding the flow and transport phenomena within the heap is critical in its design and optimization. A comprehensive heap leach model, developed within a computational fluid dynamics (CFD) framework, employs robust algorithms to solve diverse variably saturated flow conditions. The model allows for a wide array of complex thermo-fluid physics to be represented and captures suites of very complex reactions that are closely coupled with thermal conditions and key microbial populations. Employing a three-dimensional heterogeneous ‘test’ heap, a number of flow conditions are investigated and the sensitivity of metal recovery is discussed.