A study on the acidified ferric chloride leaching of a complex (Cu–Ni–Co–Fe) matte

The acidified ferric chloride leaching of an artificial matte was carried out to investigate the extraction behaviour of copper, nickel, and cobalt. The composition of the synthetically prepared Cu–Ni–Co–Fe matte was: 24.95% Cu, 35.05% Ni, 4.05% Co, 11.45% Fe, and 24.5% S. The major mineral phases of the matte were: CuFeS2, CuS2, (FeNi)9S8, (FeNi)S2, Ni9S8, Ni3S2, (CoFeNi)9S8 and Co metal. The effects of time (0–7 h), temperature (30–90 °C), FeCl3 (0.5–2.0 M) and HCl (0.1–0.5 M) concentrations were studied with and without the presence of an organic solvent (CCl4). The Cu extraction was fast compared to Ni and Co and reached equilibrium within 3 h in FeCl3 medium. The extraction of all the three metals increased with increase of temperature. The effect was found to be the maximum for Co, followed by Ni and Cu. Under optimum conditions (1.5 M FeCl3, 0.3 M HCl, 90 °C and 7 h), 99.5% Cu, 93.2% Ni and 85.2% Co was extracted to the solution. When carbon tetrachloride was added to the reaction medium, the extraction of metals increased due to the solubilisation of elemental sulphur coated around the sulphide mineral particles. From the XRD study the undissolved Ni phase was found to be (FeNi)9S8 and undissolved Co phase was cobalt metal.