Extraction of Cu and Ni from Low-Ni Matte by a Combined Chemical Precipitation and Molten Salt Electrolysis Approach

The extraction of Cu and Ni from low-Ni matte in an efficient and green manner is essential to harvest value-added metals with minimum environmental footprint. Herein, a combined approach of chemical precipitation and molten salt electrolysis was used to extract valuable metals (Cu and Ni) from the low-Ni matte. First, the low-Ni matte was converted and separated into CuS and NiS by ammonium chloride roasting, and then, it was water leached and precipitated. Fe was removed from the leachate solution by adjusting the pH value, and the separation of Cu and Ni was carried out by adjusting the temperature, S-to-Ni molar ratio, and precipitation time. The obtained CuS and NiS were then separately converted to sulfur gas at the anode and Cu and Ni at the cathode in molten NaCl-KCl. The reduction behaviors of CuS and NiS were studied using cyclic voltammetry (CV). This study proposes an eco-friendly way to extract valuable metals from low-Ni matte.