Indium extraction from LCD screens

Abstract

Liquid crystal display (LCD) screens are present in a variety of electronic devices including televisions, computers, cell phones, global positioning system (GPS) devices, and others. On a vitreous layer of their inner surface these screens contain the chemical element indium. The presence of this element, considered a critical raw material due to its economic importance and scarce availability, renders the recycling of these screens increasingly attractive. The present study therefore was undertaken with the aim of extracting indium present in LCD screens. Damaged or obsolete monitors with LCD screens were collected and dismantled manually to remove the glass layer containing indium, and subsequently, the glass layer was ground in a ball mill. After grinding, leaching tests for indium extraction were performed. Hydrochloric acid (HCl), at different temperatures and concentrations, was tested as a leaching agent at solid/liquid ratios of 1/100 and 1/10. The results obtained reveal the possibility of extracting indium, with the best result being obtained with HCl 6 M, 60°C, s/l ratio 1/100, with 298 mg In/kg.