Recovery of indium from scrap TFT-LCDs by solvent extraction

Recovery of indium from scrap LCDs, which contain indium in the form of indium tin oxide (ITO) films, is becoming economically and environmentally justified. Indium is a precious metal and the present study was aimed to recover indium from scrap TFT-LCDs by solvent extraction which was based upon H2SO4 acid leaching-D2EHPA extraction-HCl back extraction. The results showed that indium could be better leached in H2SO4 (1:1, v/v) acid solution in the optimal liquid/solid ratio of 1:1 while other metals' leaching concentrations were relatively low. Indium could be selectively extracted from its H2SO4 solutions by 30% D2EHPA with O/A ratio of 1:5 within 5 min, and be completely stripped by 4M HCl from D2EHPA with A/O ratio of 1:5, the final extraction efficiency achieved more than 97%. (C) 2012 Selection and/or peer-review under responsibility of Basel Convention Coordinating Centre for Asia and the Pacific and National Center of Solid Waste Management, Ministry of Environmental Protection of China.