Abstract:It is rich of zinc resource, most of which exist in forms of marmatite bearing indium in China. In order to recycle the valuable metal rich in neutral leaching residues in the process of zinc hydrometallurgy, the testwork of reduction acid leaching on neutral residue mixed with zinc concentrate with high-iron sphalerite as the research object has been taken in the paper. The primary objectives are to leach the zinc and indium remaining in the neutral leach residue as ferrite, using acid, and to reduce the ferric iron in solution to the ferrous state by reaction with zinc concentrate, thereby extracting the zinc and indium in the zinc concentrate.The effecting factors such as mass ratio of neutral residue and zinc concentrate, initial concentration of sulfuric acid, reaction time, liquid-solid ratio, temperature on leaching efficiency of zinc and indium have been studied in detail and finally obtain the best technical parameters: mass ratio of neutral residue and zinc concentrate 1:0.25, material particle size less than 0.074mm, initial concentration of sulfuric acid 220g/L, reaction time 3h, liquid-solid ratio 6mL/g, temperature 90℃. The results showed that the leaching efficiency of zinc and indium were over 96%, besides, nearly 95% Fe was Fe2 in the leaching solution that was suitable for subsequent process under the optimal conditions, which effectively extracts zinc and indium and converted Fe3 into Fe2 in solution.