Crystallizing Copper Sulfate from Leaching Solutions

摘要

This work offers an alternative for assaying minerals that small-scale miners cannot sell to the Empresa Nacional de Minería (ENAMI). To achieve this, we worked with a pregnant leaching solution (PLS) product from these minerals by small mining companies near Antofagasta. This project's objective was to obtain high-purity commercial-quality copper sulfate and copper chloride crystals using laboratory-scale solar evaporation pools. The minerals were 1.6 % soluble copper which were leached in columns containing 22 kg of mineral and then irrigated with solutions of 10 g/L of sulfuric acid with both tap and sea water to obtain PLS, from which crystallization was obtained. Different crystallizing salts were obtained through PLS's gradual evaporation tests in pools. The concentrations and properties of the PLS were analyzed during evaporation, and the crystals were characterized by X-ray diffraction. Calcium salts were then precipitated through crystallization by evaporation in both solutions. Copper recovery in the PLS solution with potable water was 78 % in copper sulfate form at 99.9 % (chalcanthite). Copper chloride mixed with copper sulfate was obtained using seawater and copper recovery was insufficient to be considered. The physicochemical properties were also determined as well as copper sulfate and copper chloride saturation curves in the PLSs with tap and seawater at different H_2SO_4 concentrations. These findings will contribute to process designs.