From high-impurity waste indium tin oxide (ITO) targets to high-purity nano-In2O3: In, Sn, Al, and Mo leaching and separation mechanisms

Indium (In) is a typical critical metal, and the recycling of waste In-Tin oxide (ITO) target can alleviate the In resource supply scarcity. The dismantling and preprocessing of waste ITO targets inevitably introduce metallic impurities, posing significant challenges for In recovery, particularly the separation of In from Sn and the removal of other impurities. This study developed an integrated hydrometallurgical process to prepare high-purity nano-In 2 O 3 from high-impurity waste ITO, highlighting on the leaching and separation mechanisms of In, Sn, Al, and Mo. The process consists of HCl leaching for Mo separation, selective sulfide precipitation for In/Sn separation, TOA/TBP synergistic extraction for In/Al separation, and calcination for nano-In 2 O 3 preparation. Under optimal conditions, HCl leaching extracted over 94% of In, Sn, and Al while selectively suppressing Mo dissolution to below 13%. The HCl leaching, sulfide precipitation, and solvent extraction mechanisms are also discussed in this study. The final In 2 O 3 product was 99.98% pure, with about 25 nm average particle size and 77.8% overall In recovery. This work provides an efficient route for high-purity nano-In 2 O 3 production from high-impurity wastes.