Kinetics of sphalerite dissolution for potential zinc recovery via oxidative leaching

Abstract

In this study, the leaching of zinc from sphalerite in nitric acid (HNO3)/hydrogen peroxide (H2O2) binary solution was examined via kinetic study. The result showed that the amount of zinc leached increased as the temperature and leachant concentration increased, from 53.8 to 91% for H2O2 concentrations of 2 and 10 M; 53 to 93.2% for temperature of 30 and 90°C, respectively, and decreased as the solid/liquid ratio and particle diameter increased from 92.3 to 55.9% for S/L ratios of 20 and 50 g/L; 93.4 to 51.1% for particle diameters of <75 µm and <425 µm, respectively. The solid film diffusion model provided the finest description of the experimental data while chemical reaction was established as the rate-limiting step, with activation energy of 26.52 kJ/mol. Hence, a binary solution of HNO3 and H2O2 was established as a viable route towards recovering zinc from sphalerite.