Abstract:Indium, as a multi-purpose rare metal, has a wide range of application prospects and will have great economic benefits if it can be recycled efficiently. However, the complex form of the existence of indium makes the extraction of indium very difficult, so how to efficiently recover indium from indium-bearing materials becomes the key problem in technology. The process of "sulfation roasting and multi-stage countercurrent water leaching" was adopted to realize the efficient leaching of indium applying the lead-bearing soot from the complex lead-based polymetallic solid waste co-smelting process as raw materials. The effects of roasting temperature, roasting time, mass ratio of acid to material, and water leaching temperature, time, and ratio of liquid to solid on leaching rate of indium were investigated. The results show that the best leaching effect of indium is achieved under the conditions including roasting temperature of 330 ℃, roasting time of 4 h, mass ratio of acid to material of 0.5 g/g, water leaching at room temperature, water leaching time of 2 h and ratio of liquid to solid of 5 g/g. Compared with conventional leaching and oxygen-pressure leaching, the leaching rate of indium rises to 96% above, and the efficient leaching of indium is achieved.