Pressure Oxidation of Nickel Concentrates to Prepare Mixed Hydroxide Precipitate: An Alternate Battery Supply Chain Feed Source

The demand for nickel and cobalt salts for lithium-ion battery manufacture is expected to continue to increase as electrification of the transportation sector accelerates. Nickel concentrates typically are smelted and refined to produce Class 1 nickel products which can be used to manufacture metal salts. Alternatively, a process has been conceived to pressure oxidize nickel sulfide flotation concentrate to produce mixed hydroxide precipitatePrecipitate (MHP) containing nickel and cobalt. MHP is often produced from nickel laterite operations and MHP may be refined to produce battery grade metal salts. The process uses a medium temperature autoclave (150 °C) to extract Ni, Co, Cu from the nickel concentrate into solution. The solution is then purified by pH adjustment with limestone, followed by copper recovery as a copper sulfide precipitatePrecipitate. The purification residue and the autoclave residue form a single combined residue. The copper-free solution then goes through a further impurity removal step for polishing Al/Fe and then into MHP precipitation with magnesia addition. The final product is high-grade MHP which can be used as a precursor to be making battery salts (NiSO4 and CoSO4) for lithium-ion batteries.