Recoveries of metallic indium and tin from ITO by means of pyrometallurgy

With respect to a new pyrometallurgical process for the recoveries of metallic indium and tin from ITO (Indium Tin Oxide) scrap, laboratory scale experiments have been conducted to verify the proposed process for practical purpose. The process consists of two stages of reaction. At the first stage, ITO is reduced to In-Sn alloy with CO at a low temperature. At the second stage, indium in the In- Sn alloy preferentially vaporizes at a high temperature due to the difference between the vapor pressure of indium and that of tin. In the first stage of the process, 70 vol% CO, 1023 K and 90 min are desirable for reducing atmosphere, reduction temperature and reduction time, respectively, for the reduction of ITO with CO to In-Sn alloy. As for the second stage, the temperature more than 1373 K is required for rapid preferential vaporization of indium under vacuum.