Recycling of the indium scrap from ITO sputtering waste

Abstract

Indium components have been successfully recovered from indiumcontaining scrap powders collected by the sand-blasting of sputtering chamber walls. A two-step air-classifier was used for the classification of the scrap powder. The raw scrap powders containing 10 wt% indium were classified into 12 lots according to the revolutions per minute of a classifying wheel: 6,000, 8,000, 10,000, and 12,000 rpm. The enrichment of indium component was possible in fine overflow fraction, that is, the third classified fractions at all wheel speeds, while the indium components were not concentrated in the first classified fraction. The grade of the indium components became higher with decreasing particle size and the highest grade was obtained in the third classified fraction. The purity of the indium component improved to 17.4 wt% and the recovery of the indium component was in the range 94.2-96.2% for the second and third classified fractions. The recovery and enrichment of indium should be optimized for the maximum recycling of the indium components, which can be used as raw materials in the subsequent electro-refining processes.

Commercial process for the recovery of metals from ITO etching industry wastewater by liquid–liquid extraction: simulation, analysis of mechanism, and mathematical model to predict optimum operational conditions

“…12 Hong et al reported the recycling of In from ITO-sputtering waste, which mostly deals with the enrichment of In-containing waste powder from a sputtering chamber wall. 13 Hsieh et al and Li et al proposed a pure indium recovery method from ITO scraps using a hydrometallurgical route. 14,15 Several waste resources have been studied for the recovery of In, such as ITO-scrap, [14][15][16] end-of-life liquid crystal displays and etching waste, 17,18 for prospective secondary resources for In.…”

Use of and Occupational Exposure to Indium in the United States

“…(18–21) Indium recovery from ITO targets can involve crushing and heating, processes that may expose workers to indium-containing aerosols. (22,23) Interest is also growing in recovering indium from etching waste, (24,25) sputter shield residues, (26) LCD glass, (27,28) and electronic scrap. (29) …”

Recycling of Spent Indium–Gallium–Zinc Oxide Based on Molten Salt Electrolysis

“…9,10 Moreover, the proportion of scraps generation during the sputtering process is large because only about 30% of the material can be deposited on the substrate. 11,12 A large amount of spent IGZO with low impurity content is produced from the residual of target magnetron sputtering, defective products in the sintering process, and residual products in the machining process. Consequently, a sustainable route for recovery of indium, gallium, and zinc, especially indium and gallium from spent IGZO, deserves more attention.…”

“…As a channel material adopted in thin film transistors, indium–gallium–zinc oxide (IGZO) exhibits high electron mobility, excellent surface uniformity, good optical transparency, and a low-temperature deposition capability. − Such advantages enable IGZO to be widely used in electronic and optoelectronic devices such as radio frequency identification tags, smart cards, and other types of flexible electronics in addition to display application. − As important strategic metals, the reserves of indium and gallium in the Earth’s crust are low, and the extraction process is complicated. , Moreover, the proportion of scraps generation during the sputtering process is large because only about 30% of the material can be deposited on the substrate. , A large amount of spent IGZO with low impurity content is produced from the residual of target magnetron sputtering, defective products in the sintering process, and residual products in the machining process. Consequently, a sustainable route for recovery of indium, gallium, and zinc, especially indium and gallium from spent IGZO, deserves more attention.…”