The Leaching Behaviour of Indium and Impurities from the LCD Glass of Smartphones and Tablets

Primarily, the mechanical removal of LCD panels from smartphones was examined, and a relatively easy and quick manual method was established. The LCD panels can be separated from the rest of the screen in a few seconds. In the cases of more tightly packed applications, the whole screen can be directly ground to a fine powder. The separated LCD screens were leached in different concentrations of HCl and H2SO4. The latter was found as practically more advantageous. Leaching with slightly acidic solutions (0.1 M H2SO4) results in longer leaching time, however solutions with higher purity can be obtained. If further purification is required, a relatively straightforward method of selective hydrolytic precipitation has also been examined. The practically recoverable amounts of indium may be close to the 400 mg/kg level in a dilute sulphuric acid solution containing less than 10 mg/dm3 of total impurities (Fe, Zn, Al, Cr, Ni and Cu).