China Nonferrous Metallurgy

In the process of zinc hydrometallurgy, most of indium in zinc concentrate is left in the neutral leaching residue. Compared with other In recovery processes, the In replacement & precipitation method boasts such advantages as small amount of In precipitation residue and high In content in the residue; however, the Fe content in the neutral leaching residue is relatively high, the solution after In precipitation needs for Fe removal treatment. To realize high efficient In enrichment and Fe resource recovery, neutral leaching residue and leachate are used to carry out experimental study on the process of In replacement & precipitation with zinc powder and the process of hematite Fe removal from the solution after In precipitation. The results show that the preferred In precipitation conditions are endpoint pH=4.0, reaction temperature at 80℃, zinc powder dosage of 8g/L and reaction time lasting 1.5h, under such conditions, the average precipitation efficiency of In is 97.23%, the In content in the residue is 2.15%; the preferred hematite Fe removal conditions are reaction temperature at 200℃, reaction time of 180min, oxygen partial pressure of 0.3MPa, under such conditions, the precipitation efficiency of Fe is 97.12%, the Fe and S contents in the residue are 60.37% and 1.84% respectively. The Fe precipitation residue (hematite residue) can be sold as raw material to cement plants.