Hydrothermal pretreatment of chalcopyrite concentrate with copper sulfate solution

Abstract

The existing technologies for porphyry copper ores beneficiation, located in deposits in the Urals of Russia, allow the production of chalcopyrite concentrates with a copper content of 19 to 30%. Subsequent technology for the concentrates processing includes autogenous smelting, matte desulfurization, and blister copper refining operations. The current work presents a new hydrometallurgical approach for the copper concentrate enrichment up to a higher grade of 50–55% Cu, which could significantly increase the production capacity and efficiency of smelting and with a process simultaneously avoiding the matte desulphurization operation. The suggested method consists of oxidative pressure leaching followed by hydrothermal pretreatment of chalcopyrite concentrates with copper sulfate solutions. The pressure oxidative leaching of the chalcopyrite concentrates allows Cu extractions up to 99% and produces Cu-rich solution for the hydrothermal pretreatment stage. Optimization of the hydrothermal pretreatment stage was carried out within the following limits: T = 150–230 °C, CuCuSO4/CuCuFeS2 = 1.2–3.3, H2SO4 = 20–120 g/L. Recommended parameters were established as T = 230 °C, CuCuSO4/CuCuFeS2 = 1.8–1.9, H2SO4 = 20–40 g/L, t = 60–100 min since this allows concentrate to be obtained with Cu content of 51–52% and residual Cu concentrations of as low as 0.08–0.13 g/L in the final solution. A parametric model of the hydrothermal pretreatment stage was obtained. The solutions and residues after hydrothermal pretreatment of the material were analyzed for their chemical and phase composition. A technological flowsheet, as well as strategies for by-product processing, were also suggested.