Modelling in-situ recovery (ISR) of copper at the Kapunda mine, Australia

In-situ recovery (ISR) is a low-cost, percolation leaching method that recovers minerals by dissolving them in situ with a lixiviant and extracting the product through bore holes. It is widely used for uranium production and is increasingly being considered for the extraction of copper and other metals. Evaluating ISR mining projects requires a reliable prediction of the operational and commercial potential for extracting minerals by ISR. The predicted production can be evaluated by simulating the solution extraction process in the subsurface using reactive transport modelling techniques. This paper presents a case study in which the in-situ copper recovery from an abandoned mine site at Kapunda, Australia is evaluated as part of a scoping study. In this study, copper leaching and the transport of the resulting solution under well operating conditions (injection and extraction) are modelled over the mining area. COMSOL Multiphysics was used to establish an integrated simulation model of reactive fluid flow through different domains, including wells, fractured rock masses and old underground workings from previous mining operations. This paper also describes the derivation of the major input parameters from site investigations including the estimation of hydraulic conductivity from the fracture information and the copper leaching rate from the initial leaching tests. The potential for the Kapunda mine site to become the first operating in-situ copper recovery mine in Australia is currently being evaluated and the project is currently at the scoping study stage. This paper contributes to the evaluation by presenting an ISR copper production model for the Kapunda site that can be used in an initial economic analysis.