Ferric Leaching of Bulk Sulfidic Concentrates with Biologically Generated Solution

The leaching of nonferrous metals from copper-zinc and copper-nickel sulfidic concentrates with a ferric sulfate solution obtained via microbial oxidation of ferrous sulfate was studied under different conditions (temperature, pulp density, and oxidant concentration). The highest concentration of nonferrous metals in the liquid phase was reached at 80 degrees C. The pulp density was shown to have no significant effect on copper leaching, although an increase from 1 to 3% decreased the release of zinc and nickel into the liquid phase. The study of the effect of the oxidant (Fe3+) concentration indicated that recovery of zinc and nickel reached its maximum at 10 g/L of Fe3+. In all studied modes, zinc was released into the liquid phase more efficiently than nickel; however, copper was mainly concentrated in the residues of both concentrates. The contents of zinc and nickel were shown to decrease from the initial values of 7.36 and 9.45% to 0.05 and 6.86% in the leach residues, respectively, while the copper content increased in both cases. The proposed method for selective mineral leaching from bulk concentrates may be considered a process step to improve the grade of sulfidic concentrates.