Sulfuric acid leaching for capturing value from copper rich converter slag

In this research, a hydrometallurgical method for recovery of copper from copper rich converter slag is investigated. The main copper containing phases of the slag are cuprite (Cu2O), delafossite (CuFeO2) and metallic copper (Cu). The study investigates the effect of particle size, temperature, acid concentration, agitation and leaching time under oxidizing conditions. The results showed that at optimized conditions (40 °C, 2 M H2SO4, 60 min leaching time, 0.26 kW/m3 mixing power, and 2000 mL/min oxygen flow rate), ca. 100% extraction of copper from slag into the solution was obtained. X-ray diffraction (XRD) analysis consolidated the experimental results by confirming that no Cu containing phases were present in the leach residue. Results also showed that temperature ≤40 °C had the larger influence on Cu and Fe yield, whereas higher temperature (>40 °C) favored Ni and Zn dissolution. The acid consumption of the optimized leaching process was found to be 23.7 mol of H2SO4 per kg of copper.