Research on the short-process of leaching and semi-extraction method of nickel‑cobalt from mixed hydroxide precipitate (MHP) to prepare battery grade products

Abstract

Mixed nickel‑cobalt hydroxide precipitate (MHP) obtained via pretreatment and leaching of nickel laterite ore, is a vital source of nickel and cobalt. This work proposes an efficient and economical hydrometallurgical process for recovering Ni and Co from MHP. Initially, an acid leaching process was employed, achieving leaching efficiencies of 99.9 % for Ni and 98.3 % for Co. Notably, the leaching efficiency for Mn was significantly lower at 26.1 %, attributed to partial oxidation of Mn. Subsequently, the purification of the leach liquor resulted in a significant reduction of impurities such as Si, Sc, Fe, and Al to concentrations of 18 mg/L, 1.8 mg/L, 0.8 mg/L, and 0.8 mg/L, respectively. Finally, the subsequent semi-extraction process further minimized impurities, including Co, Mn, Mg, and Ca, to levels below 1 mg/L in the purified solution. Furthermore, the Sc enriched in P204 was stripped by 3 mol/L NaOH, yielding a Sc-enriched solid residue with a grade of 30 %. The results show that the process can extract Ni and Co from MHP, and Ni, Co solution are suitable for the production of lithium batteries.