Leaching of a sphalerite concentrate with H2SO4–HNO3 solutions in the presence of C2Cl4

The enhanced leaching of sphalerite concentrates in H2SO4–HNO3 solutions and the extraction of sulfur with tetrachloroethylene were studied. Variables of the process were investigated including leaching temperature, reaction time, liquid / solid ratio, and tetrachloroethylene concentration. The number of cycles that tetrachloroethylene could be recycled did not have a significant effect on zinc extraction. The results indicated that 99.6% zinc extraction was obtained after three hours of leaching at 85 °C and 0.1 MPa O2, when 20 g of sphalerite concentrate were leached in a 200 ml solution containing 2.0 mol/L H2SO4 and 0.2 mol/L HNO3, in the presence of 10 ml C2Cl4. Leaching rates were significantly improved under these conditions.