Targeted Coordination-Controlled Iron Precipitation in the Zinc Hydrometallurgy Process: A Green Strategy for Fe–Zn Separation

The efficient separation of Fe from zinc hydrometallurgy leachate, particularly at excessive Zn2+ concentrations, remains a major challenge. Conventional methods rely on high temperatures and alkaline environments, making it difficult to control the solubility of Zn2+. Moreover, Zn2+ tends to coprecipitate with Fe at high pH levels, significantly limiting the resource utilization efficiency. To address this bottleneck, this study introduces an innovative Fe–Zn selective separation strategy based on coordination regulation, operating under mild temperature and alkalinity. The introduction of multiple active functional groups enables precise control over the targeting coordination of Fe3+ and Zn2+. At only 30 °C and 1 mol/L OH–, OH– promotes autocatalytic transformation of Fe2+/Fe3+, ultimately driving the selective formation of magnetite. Meanwhile, thiol and amine groups, acting as soft base ligands, exhibit a strong affinity for Zn2+, stabilizing it as a soluble complex. This strategy breaks the technical barriers of traditional Fe–Zn separation with high energy consumption, excessive alkali use, and poor selectivity. By establishing a novel separation paradigm based on molecular-level coordination control, the selectivity is enhanced, and the reliance on extreme conditions is significantly reduced. This approach offers a green and efficient solution for metal separation, wastewater treatment, and resource recovery.