End-of-Life Liquid Crystal Display Recovery: Toward a Zero-Waste Approach

Abstract

End-of-life liquid crystal displays (LCD) represent a possible source of secondary raw materials, mainly glass and an optoelectronic film composed of indium (90%) and tin (10%) oxides. A strong interest for indium, classified as critical raw material, pushed research towards the development of high-efficiency recycling processes. Nevertheless, a deepened study of the technological innovation highlighted that only a small number of treatments included use of whole waste. Furthermore, these processes often need high temperatures, long times, and raw materials that have a significant environmental impact. In this context, this article shows an approach developed in accordance with the “zero waste” principles for whole, end-of-life LCD panel recycling. This process includes preliminary grinding, followed by cross-current acid leaching and indium recovery by zinc cementation, with efficiencies greater than 90%. A recirculation system further increases sustainability of the process. To enhance all waste fractions, glass cullets from leaching are used for concrete production, avoiding their disposal in landfill sites. Considering the achieved efficiencies, combined the simple design suitable for real-scale application (as confirmed by the related patent pending), this process represents an excellent example of implementing circular economy pillars.