Investigation of the effect of different parameters on lixiviant ion migration in a laboratory scale study of electrokinetic in-situ recovery

Abstract

ABSTRACT In situ recovery (ISR) has the potential to recover metals at a lower cost, create less waste and significantly reduce energy usage and the environmental footprint of a mining operation compared with conventional mining. Only preliminary research has been conducted on ISR-related mass transfer enhancement methods. Improved mass transfer may allow for greater contact of lixiviant with ore surfaces in an ISR operation, improved leaching kinetics and an increased overall metal recovery from the in-situ environment. One approach to improve mass transfer in ISR is to use an electrokinetic method. The electrokinetic method induces ion migration using an electric potential difference across a medium immersed in liquid. The focus of this study was twofold: to evaluate the effect of different parameters on the migration of ions in an electrokinetic setup and to propose a standard laboratory-scale setup to perform mass transfer measurements for ISR. A series of experiments were conducted in which the propagation of lixiviant solution in an electrokinetic setup was monitored and the experimental results were analyzed by different methods. Experiments were performed using different voltages (but in a constant voltage setup) using two experimental setup configurations (with and without hydraulic pressure), synthetic core samples of different permeabilities and different membrane types at the ends of the experimental setup middle section. It was found that an increase in applied voltage across a non-reactive silica sample increased ion migration. At 20 V and above, more ions moved to the target reservoir over 4 days compared with 15 V, and at 15 V, more time was needed to reach maximum ion migration. The use of different membrane types did not affect lixiviant ion migration significantly. Lower-permeability synthetic core samples hindered lixiviant ion migration.