Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

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 pyrometallurgy for metal recovery. 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 robust 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 a Au-Ag bearing sulfide flotation concentrate by deep eutectic solvent ethaline with iodine as oxidizing agent is used as a relevant case study. Results show that time lapsed CT provides an accurate estimation of the dissolution rate of pyrite, chalcopyrite, galena, telluride minerals and gold. Dissolution rates were used then to simulate metal recoveries from the mineral concentrate as a function of leaching time. Simulation results are within 5% variation of recoveries obtained by batch leaching experiments. The developed workflow can be easily transferred to other mineral concentrates or ore types; results may be used to optimize industrial leaching process.