Dissolution behavior of a complex Cu–Ni–Co–Fe matte in CuCl2–NaCl–HCl leaching medium

The paper reports leaching studies on a complex Cu–Ni–Co–Fe matte with cupric chloride in an acidic and strong brine solution. The influences of cupric chloride, NaCl, HCl, time and temperature have been studied. The role of sulphate and carbon tetrachloride in the leaching medium has been evaluated with respect to metal extraction efficiency. On the basis, it has been possible to define a suitable combination of process parameters for leaching out most of the associated copper, nickel and cobalt values and to generate a solution low in iron. Copper and nickel extractions were found to be fast and reached equilibrium within 2 h, compared to cobalt, which need prolonged leaching to reach equilibrium. Whereas, after an initial fast reaction rate, iron concentration in leach solution slowly decreased with time. Under optimum conditions (Cu(II) 70 g L−1, temp. 120 °C, NaCl 300 g L−1, HCl 0.5 M, 6 h), 95.2% Cu, 98.4% Ni, 83.6% Co and 16.8% Fe were extracted to the leach solution. The leaching process was found to be enhanced by elevated temperature, high chloride and Cu(II) concentrations. The metal extractions were unaffected up to 10 g SO4 in the leaching medium. The presence of CCl4 did not improve the metal extraction efficiency.