China Nonferrous Metallurgy

Zinc concentrate generally contains 0.5%-1.0% copper, and 50%-70% of the copper remaining in the leaching residue during the conventional leaching process cannot be recovered in the fire volatilization process, and can only be left in the kiln slag or other slag. A zinc hydrometallurgy plant in Yunnan adopts the conventional leaching and rotary kiln volatilization process to treat the zinc leaching residue. The rotary kiln slag produced is processed by the blast furnace process when the copper price is high, and the slag was sold out directly when the copper price is low, and the profit is lower. In order to recover the copper in the leaching residue, the plant demonstrated the feasibility of the hot acid leaching-class goethite process to replace the conventional leaching process on the basis of a large number of experimental studies, and the following conclusions were drawn. The zinc leaching residue is treated by the hot acid leaching-class goethite process, and zinc roasted ore is used as the neutralizer, the slag rate is 32.51%, the zinc leaching rate is 92.29%, and the copper leaching rate is 74.33%. The zinc leaching slag is treated by conventional leaching process, the slag rate is 46%, the zinc leaching rate is 85%, and the copper leaching rate is 40%. It is not economical to use secondary zinc oxide powder to replace zinc roasted ore as a neutralizer. Adding an ultra-high acid leaching process after high acid leaching can increase the copper recovery rate by 5.72%, but the return on investment is low.