China Nonferrous Metallurgy

In China, sulfuric acid leaching process is widely used to recover indium from lead and zinc smelting dust. With the increase of tin content in the dust, the leaching rate of indium shows a decreasing trend and is generally less than 60% in sulfuric acid. Targeted at the complex lead-zinc smelting dust containing In₂O₃·xSnO₂, this paper proposes the chlorination leaching process of lead-zinc smelting dust to recover indium. The influence of factors such as sodium chlorate concentration, hydrochloric acid concentration, leaching temperature, sulfuric acid concentration, leaching time, liquid-solid ratio on the leaching rate of indium were investigated. The results showed that the average leaching rate of indium resulted from chlorination leaching reached 92.7% under the following conditions of sodium chlorate concentration of 20g/L, hydrochloric acid concentration of 48g/L, leaching temperature of 80℃, sulfuric acid concentration of 225g/L, leaching time of 3.0h, and liquid-solid ratio of L/S=5∶1(L/kg). Thus, this process can be used in the production practice to recover indium through the treatment of the complex lead-zinc smelting dust.