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.