Recovery of indium and yttrium from Flat Panel Display waste using solvent extraction

Oxides of indium and yttrium are two of the key components in Flat Panel Displays (FPDs). In recent years the need to recycle these metal oxides from waste FPDs has been growing. In this work a process to recycle indium and yttrium based on acid leaching and solvent extraction was proposed and studied. Solid waste was leached by acid at S/L ratio = 0.1 g/ml, HCl was found to be more effective than HNO3, possibly due to the formation of soluble metal chloride complexes. The extraction of indium using Cyanex 923 and yttrium using DEHPA from chloride media studied using lab-scale mixer-settlers at a flow rate of 3 ml/min. Leachate of real FPD waste was used as aqueous feed. Good separation between indium, yttrium and other impurities such as iron, copper and aluminum could be achieved by extraction from 1 M HCl with 0.25 M Cyanex 923 diluted in kerosene, followed by stripping with 1 M HNO3 and further purification with 0.2 M DEHPA diluted in kerosene