環境・リサイクル

[3401-11-08] Recovery of indium and gallium from spent IGZO targets by leaching and solvent extraction

○Shuai Gu¹, Gjergj Dodbiba¹, Toyohisa Fujita¹ (1. Graduate School of Engineering, The University of Tokyo)

司会：晴山 渉（岩手大学）

Keywords:IGZO, Extraction

Indium, gallium, and zinc oxide (IGZO) is a semiconducting material, which is widely used in the manufacturing of semiconductors, touch panels, displays, etc. This work aims to shed some light on the recovery and separation of indium, gallium, and zinc from spent IGZO targets by solvent extraction (SX). The process involves leaching, SX in high acidity, stripping, re-extraction in low acidity, re-stripping, followed by the cementation of the gallium and indium with zinc dust. Triisobutyl phosphate (T-iso-BP) was employed as the extractant to separate the majority of zinc from indium and gallium in the leaching solution. The leaching solution was utilized directly without further adjustment, which avoided consuming an enormous amount of water. The loaded organic (LO) solution was then stripped with HCl solution at pH= 2, moving the majority of indium and gallium from LO phase to aqueous phase. The extraction and stripping process enabled the transfer of indium and gallium from the leaching solution (8-8.5 mol/L HCl solution) to HCl solution at pH= 2, without diluting the leaching solution with an enormous amount of water. The stripped solution was then extracted with Di-(2-ethylhexyl) phosphoric acid (D2EHPA) to separate indium from gallium. The optimum extraction conditions and stripping conditions were studied. 97.8% of indium with a purity of 98.3% and 96.2% of gallium with a purity of 99.6% were separated and recovered, respectively, from the actual spent IGZO target.