The effect of H2SO4 concentration and time on the sphalerite leaching process

• Published in: AIP conference proceedings 2024-04, Vol.3071 (1)
• Main Authors: Kurniawati, Riskaviana, Dahani, Wiwik, Subandrio, Herdyanti, Mixsindo Korra, Purba, Imanuel
• Format: Article
• Language: English
• Subjects: Heavy metals; High temperature; Hydrometallurgy; Leaching; Oxidizing agents; Photomicrographs; Pyrite; Sulfur; Sulfuric acid; Zinc; Zinc sulfide; Zincblende
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/5.0207659

Galena is frequently found in association with other sulphide minerals such as sphalerite and pyrite. The pyrometallurgical methods, is commonly used for zinc recovery and requires high temperatures, resulting in heavy metal pollution and SO2, making it unsuitable for the environment. In this study, the use of H2SO4 without an oxidant for direct leaching of sphalerite concentrate was investigated. The sphalerite concentrate (200 mesh) was roasted for 3 hours at 700°Cto reduce the sulphur content in the sample. Following that, leaching was performed using a sulfuric acid solution with a concentration range of 1-6mol/L for 1-5 hours. The zinc levels in the leached solution were determined using XRF (X-RayFluorescence) and SEM (Scanning Electron Microscopy). Before the leaching process, the particles of zinc sulphide concentrate have a clear surface and are roughly the same shape and size. The micrographs of the leaching residues show a progressive increase in the roughness of the solid as well as an increase in the amount of elemental sulphur covering theparticle surfaces after the leaching process. The presence of sulfuric acid is clearly important in the leaching process, as zinc extraction rate increased with increasing sulfuric acid concentration, but only up to 3 mol/L. The highest zinc extraction, 99.17%, was obtained at 2 mol/L H2SO4 after 3 hours.