Calciothermic reduction of NiO by molten salt electrolysis of CaO in CaCl2 melt

Metallic nickel powders with low and uniform residual oxygen content were produced from NiO using the molten salt electrolysis of CaO in CaCl₂ melt. Suitable amount of CaO for the reduction was in the range of 0.5–3.0 mol% CaO.The electrical isolation of NiO from both electrodes could produce metallic Ni in CaCl₂ melt. Separating the metal oxides from the cathode confirmed the mechanism of calciothermic reduction that the electrolysis of dissolved CaO in CaCl₂ melt produces Ca, and that the dissolved Ca in molten CaCl₂ successfully reduces NiO to metallic Ni. An average of about 600 ppm oxygen in Ni sample was achieved directly from oxide, when NiO was detached from the cathode.