A particle-based approach to predict the success and selectivity of leaching processes using ethaline - Comparison of simulated and experimental results

Encouraged by the need for ecologically and economically sustainable technologies for the recovery of metals from complex raw materials, ionometallurgical leaching using deep eutectic solvents is emerging as a promising alternative to conventional hydro- and pyrometallurgical process routes. Current approaches of studying leaching processes do not provide a mineral-based understanding of the leaching process – thus limiting the opportunities for process optimization. This study addresses this shortcoming by combining laboratory-based X-ray computed tomography (CT) and scanning electron microscopy-based image analysis. The latter method provides precise information on the mineralogy and texture of the leach feed material, whereas CT is used to observe the progress of the leaching process through time. Leaching of Au[sbnd]Ag bearing sulfide flotation concentrate by the deep eutectic solvent ethaline with iodine as oxidizing agent is used as a relevant case study. Results show that time-lapse CT provides an accurate estimation of the dissolution rate of pyrite, chalcopyrite, galena, telluride minerals and gold. Dissolution rates were used to simulate the metal recoveries from the sulfide concentrate as a function of leaching time. Simulation results are within 5% variation of metal recoveries obtained by batch leaching experiments. The developed workflow can be easily transferred to other ore types or mineral concentrates; results may be used to study and optimize industrial leaching processes.