Deep purification of copper from zinc sulfate solution using controllable aging FeS nanoparticles through slow-release sulfide precipitation

Abstract

The purification of impurity ions within zinc hydrometallurgical solutions significantly impacts the subsequent quality of zinc electrodeposition. Traditional methods for copper removal from zinc solutions suffer from issues like limited reactivity, high consumption, and elevated costs. To address these challenges, controllable aging of FeS nanoparticles was designed, employing temperature variations to facilitate comprehensive copper removal from neutral zinc leachates. The aging process imparts a crystalline structure to the FeS nanoparticles, enabling the slow release of sulfide ions. A temperature of 60°C is regarded as the optimal aging temperature, at which the resultant FeS nanoparticles exhibit an optimal sustained-release performance during the aging process. Temperature has been found to be a crucial factor influencing the sustained-release performance of FeS. Once the reaction temperature surpasses 60°C, the utilization efficiency of S ions in the sustained-release agent can reach over 95%, with a maximum of 98.5%. Under optimal conditions featuring a reaction temperature of 60°C, a reaction duration of 30 minutes, and a solution pH maintained at 1, the dosage aged FeS at the S/Cu (II) ratio of 1.2 times, nearly 100% copper removal rate can be achieved. The maximum removal rate for cadmium does not exceed 2.5%, and the residual copper concentration in the zinc leachate is below 0.2 mg/L. The precipitate obtained is high-purity copper sulfide residue, which contains virtually no zinc. Slow-release sulfidation can maximize the utilization efficiency of sulfide ions in the solution, reduce the occurrence of competing reactions, and minimize the intermixing of products. It offers advantages such as high selectivity and deep purification.