A novel process for simultaneously extracting Ni and Cu from mixed oxide-sulfide copper-nickel ore with highly alkaline gangue via FeCl3∙6H2O chlorination and water leaching

Abstract

An innovative and clean technique for simultaneously extracting Ni and Cu from mixed oxide-sulfide copper‑nickel ore using FeCl3∙6H2O chlorination was developed. This technique not only prevented environmental pollution, but also allowed the efficient recovery of valuable metals. Various roasting factors were investigated in detail to obtain the optimum conditions for the extraction of Ni and Cu: chlorination temperature of 175 °C, chlorination time of 2 h, chlorinating agent dosage of 50%, and ore particle size of 80–96 μm. After chlorination followed by water leaching, >92.33% Ni and 89.43% Cu were extracted, while, only 7.37% Fe was transferred into the leaching solution, which resulted in the Fe concentration in the leaching solution of 0.12 mol/L. The mechanism of chlorination roasting and transformation rules of the mineral phase were determined using differential thermal and thermogravimetric analysis (DTA-TG), X-ray diffraction (XRD), thermodynamic analysis of chlorination reactions, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The content of gaseous chlorinating agent produced can be controlled by the dosage of ferric chloride so that no exhaust gas is emitted. The chlorination technique using FeCl3∙6H2O provided an effective approach for the simultaneous and direct extraction of Ni and Cu from mixed oxide-sulfide copper‑nickel ore.