Copper Recovery from a Refractory Sulfide Mineral by Ferric Leaching and Regeneration of the Leaching Medium Through Catalytic Oxidation with Carbon for Recirculation

Optimizing copper recovery from sulfide minerals such as chalcopyrite, which constitutes over 70% of global copper reserves, is essential due to the depletion of conventional copper oxide resources. This study aimed to establish optimal ferric leaching conditions for a chalcopyrite-rich concentrate to maximize copper recovery and to evaluate the regeneration of the oxidizing potential in the residual leaching solution for reuse. Ferric sulfate (Fe2(SO4)3), as a ferric ion (Fe3+) carrier, was used as oxidizing agents at a concentration of [0.1 M] in sulfuric acid ([0.5 M] H2SO4), using a CuFeS2 concentrate (75% chalcopyrite) leached over 80 h. Copper was recovered through cementation with metallic iron, while the residual leaching solution, containing ferrous ions, was analyzed to determine total iron content via atomic absorption spectroscopy and to assess the presence of ferrous ions through KMnO4 titration. This step was crucial, as an excess of ferrous ions would indicate a loss of oxidizing potential of the ferric ion (Fe3+). Catalytic oxidation was conducted with microporous activated carbon (30 g/L) to regenerate Fe3+ for a second leaching cycle, achieving 90.7% Fe2+ oxidation. Optimal leaching conditions resulted in 95% soluble copper recovery at 1% solids, d80: 74 μm, pH < 2, Eh > 450 mV, 92 °C, [0.5 M] H2SO4, and [0.1 M] Fe2(SO4)3. In the second cycle, the regenerated solution reached 75% copper recovery. These findings highlight temperature as a critical factor for copper recovery and demonstrate catalytic oxidation as a viable method for regenerating ferric solutions in industrial applications.