Development of a 3D dual pore‒system leaching model: Application on metal extraction from oxide copper ore

Abstract

Leaching from packed ore beds in hydrometallurgical operations involves various sub-processes, including flow of solution, transport of leaching agent and leached product, liquid-solid reactions at the mineral surface and transfer of reaction heat, in heterogeneous multi-scale porous media. A 3D dual pore‒system leaching model based on heterogeneous ore pack geometry reconstructed from X-ray computed tomography (CT) images was developed to account for the coupled flow–transport–reaction–heat transfer processes across the pore scales of inter-particle macro-pore and intra-particle micro-pore. The model was deployed to investigate the leaching kinetics of an oxide copper ore by sulphuric acid. Ultimately, the velocity field, mineral leaching rate, concentration of leached ions, concentration of leaching agent and temperature were solved numerically by finite element method. The influence of leaching agent concentration, irrigation rate and environment temperature on the competitive leaching of malachite and gangue minerals was revealed. The dual pore‒system model is able to provide insights into the heterogeneous leaching behaviours that otherwise cannot be revealed by models built on basis of uniform geometries.