Abstract
The hydrometallurgical processing of primary and secondary copper sulfides is challenging because of leaching resistance and surface passivation. Due to their physicochemical properties, ionic liquids have shown potential in the leaching of sulfide minerals as alternatives to conventional leaching agents. This study investigates the oxidative leaching of a copper sulfide concentrate predominantly composed of covellite (CuS) and pyrite (FeS2). Leaching experiments were carried out using an ionic liquid (IL) solution based on 1-butyl-3-methylimidazolium hydrogen sulfate [bmim][HSO4] in the presence of hydrogen peroxide (H2O2) as the oxidant. The effects of key process parameters, including IL concentration (0.5–3.0 mol/dm3), H2O2 concentration (0.5–3.0 mol/dm3), temperature (25–70 °C), stirring speed (0–600 rpm), and solid-to-liquid ratio (1:100–1:10), on copper and iron extraction efficiency were investigated. The initial sample and leaching residues were characterized using X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS). The results showed that increasing temperature had the greatest influence on the process. At an elevated temperature (70 °C), maximum extraction degrees of 95% were obtained for both copper and iron. Higher selectivity for copper leaching over iron leaching was achieved by increasing the ionic liquid concentration under atmospheric conditions. The investigated IL-H2O2 system shows potential for leaching copper sulfide concentrates under relatively mild conditions without the use of concentrated mineral acids.