Process for recovery of indium from ITO scraps and metallurgic microstructures

Indium (In) can be recycled economically from used indium tin oxide (ITO) target or ITO etching solution. This study offers an efficient and simple method for recovery of pure indium from used materials using hydrometallurgical and hot immersion processes. The hydrometallurgical method (displacement) can be used to obtain indium metal from ITO waste liquid, and a slag-making process during hot immersion is proposed to purify sponge indium above 99%. The effects of replacement agents and temperatures for replacement solution are discussed using microstructure measurements for illustration. Magnesium (Mg) has the lowest oxidation potential and can be easily removed by using either oxidization or vaporization. In contrast, tin needs to be detached from an indium plate before sponge indium can form.