The
basic leached residue containing indium and silicon was produced after extracting germanium by the basic molten-
leaching process. When the residue is leached by general acidic solution, a silicon colloid is formed to make
filtration of acidic leached solution to be difficult. Tree processes for treating the
Residue to recovery indium is high concentration acid at high temperature, sulphation roasting-leaching and preparation-leaching respectively, which can all resolve the difficult filtrate problem of
Leached solution. For recovery rate of indium, the third process is the best one with leaching rate of 95% under the optimum conditions such as mass ratio of liquid to solid being 5, beginning acid concentration of 120～150 g/L, at temperature of 80～90 ℃ for 2.0 h. Rude indium more than 98% was produced from the acidic leached solution using the extractive-cement process. From rude indium, refined indium more than 99.99% by electrolysis refining process was prepared. The direct recovery rate of indium is 90% from the basic leached residue to rude indium.