Leaching of zinc sulfide in alkaline solution via chemical conversion with lead carbonate

A novel hydrometallurgical process for recovering Zn from ZnS in alkaline solution via chemical conversion with PbCO3 was developed in this work. The S originally present in ZnS can be converted into PbS, while the Zn can be converted into Na2Zn(OH)4 in the alkaline solution in the presence of PbCO3. And then, the Pb in PbS deposited in the leach residues can be converted into PbCO3 again in the Na2CO3 solution. It was found that over 90% of Zn can be extracted from ZnS when the leaching process is operated in 6 mol/L NaOH solution at 90 °C with PbCO3 as additive, and over 95% of PbS in the leach residues can be converted into PbCO3 by stirring the leach residues in Na2CO3 solution with air bubble at a temperature of 80 °C. The leaching solution can be used to produce metallic zinc powder by electrowinning after chemical separation of impurities.