Recovery of Gallium and Indium from Gallium Nitride-containing Waste

Abstract

With the expansion of LEDs markets LEDs will contribute to a large stream of solid wastes along with abundant waste electric and electronic equipment (WEEE) Due to the importance and scarcity of gallium and indium we develop the effective recycling processes of recovering gallium and indium from waste gallium nitride-containing waste LED dust The procedure was divided into the following steps alkaline roasting leaching separation and purification In the pretreatment part owing to the stable chemically properties of gallium nitride the process would concentrate on bonding rupture Hence the gallium nitride was reacted into sodium gallium oxide by alkaline roasting And the next the leaching and separation part which is mainly to dissolve the targets and separate the gallium and indium from each other including leaching and solvent extraction The optimal condition of leaching procedures and the optimal parameters including pH value concentration of Cyanex272 A/O ratio and extraction time were investigated in this study In the final purification step Ga2O3 and In2O3 were obtained by means of chemical precipitation and calcination With the optimal conditions the recovery rate of gallium and indium could reach to 99% and the purity of Ga2O3 and In2O3 are over 99% The process which was provided in this study can provide an effective method to treat the related waste light emitting diodes dust

Date of Award	2020
Original language	English
Supervisor	Wei-sheng Chen (Supervisor)