Effect of Sulfuric Acid Concentration on Marmatite Dissolution in the Presence of Cupric Ions

Marmatite often associates with copper sulfide ore with the role of Cu²⁺ in marmatite dissolution being important in hydrometallurgy. In this work, we found that cupric ions (Cu²) can accelerate marmatite dissolution significantly at high temperature, regardless of sulfuric acid concentration (pH 0.5–2.5). Marmatite dissolved faster at lower acid concentrations and compared with cupric-free conditions, and the concentration of zinc dissolved in the presence of Cu²⁺ ions increased by 5500 mg/L. When the acid concentration was high (pH above 2.5), the acceleration effect of high Cu²⁺ concentration was more obvious. In addition, the consumption of Cu²⁺ was low at high acid concentration (pH below 1.5), but Cu²⁺ consumption increased significantly at low acid concentration (pH above 2.5). X-ray diffraction (XRD) of the leaching residues proved that no copper-containing mineralogical phase was produced at high acid concentration, but copper-containing products were formed at low acid concentration. Kinetic analysis showed that marmatite dissolution was mainly controlled by surface reaction. The reaction between Cu²⁺ and marmatite should be different at different concentrations of sulfuric acid.