Selective Nickel Leaching and Preparation of Battery-Grade Nickel Carbonate from Copper-Rich Industrial Intermediate

The rising demand for electric vehicles (EVs) has driven a significant increase in nickel consumption, a critical element in EV battery production. An industrially viable hydrometallurgical process was developed for the selective recovery of nickel from a copper-rich industrial intermediate, containing approximately 70 wt.% Cu and 6 wt.% Ni, predominantly as sulfides alongside minor impurities. Approximately 90% of nickel was selectively extracted via single-stage atmospheric pressure leaching using HCl and H2O2 at 95 °C for 12 h, with the majority of copper retained in the leach residue, which can be utilized as a valuable feedstock for copper smelters. The selectivity of nickel over copper was analyzed in detail through corresponding Pourbaix diagrams, and an appropriate leaching mechanism was proposed. The leachate was subsequently purified through a sequence of cementation, selective precipitation, and solvent extraction steps to remove residual copper, iron, and cobalt, achieving an overall separation efficiency of 99% with nickel losses below 2%. In the final stage, nickel carbonate was precipitated with >99% purity using sodium carbonate, potentially suitable for battery applications. The optimal conditions at each stage were determined through batch-type laboratory-scale experiments, which may need to be verified by continuous pilot-scale testing in the future. This process offers dual advantages by meeting the growing nickel demand for battery applications while simultaneously providing additional copper feedstocks for smelters.