A critical review of hydrothermal treatment of sulfide minerals with Cu(II) solution in H2SO4 media

Hydrothermal pretreatment of copper concentrates in acidified copper sulfate solution has been known since the beginning of the last century as an approach to the chemical enrichment of copper concentrates. While the pilot-scale demonstration of this approach exists, detailed investigations into the underlying chemical interactions that form the basis of this technology are rarely available in open sources. This review attempts to summarize research data on the hydrothermal treatment of sulfide minerals for over a century. It focuses on the hydrothermal interactions between acidified copper sulfate solution and sulfide minerals, which are of key significance for the hydrothermal enrichment process, including the main copper minerals (CuFeS₂, Cu₅FeS₄, CuS, Cu₂S) and those (e.g., ZnS, FeS_2, and PbS) that are often associated with copper concentrates as penalty impurities. Studies on the hydrothermal enrichment of various sulfide raw materials (including copper concentrates) have shown that parameters such as temperature, the concentration of reagents, and the molar ratio of Cu in solution to Cu in solid, among others, influence the efficiency of the process.

Furthermore, reaction kinetics seem to assume prime importance in controlling the hydrothermal treatment process. High activation energies, fractional orders of the reactions with respect to the reagents, and diffusion-controlled kinetics characterize the hydrothermal interactions between sulfides and acidified copper sulfate solution. The findings in the literature were critically examined and discussed with the delineation of further research needs.