Indium Recovery from Waste Liquid Crystal Display via Chloride Volatilization Process: Thermodynamic Computation
Abstract
With the increase of the scrap liquid crystal displays (LCDs), recycling indium from waste LCDs has captured an international attention. Chloride metallurgy is a promising method for indium recovery from LCD panels, due to the lower boiling point of indium chloride. In the present study, thermodynamic analyses of indium recovery from waste LCDs via chloride volatilization process by the HSC Chemistry software was carried out to understand the reaction mechanism between chlorinating agent and LCDs to avoid adverse factors, and simultaneously obtain the optimal conditions for the extraction of indium. The results show that the recovered indium from LCDs with HCl as the chlorinating agent from the PVC pyrolysis is feasible, with the chlorination temperature controlled between 134.49 and 554.25 oC, and the evaporation temperature higher than 490 oC, and simultaneously, the oxygen partial pressure controlled or under anaerobic conditions. As such, the influences of SiO2 , Al2O3 and Fe2O3 , contained in LCDs, can be ignored or avoided, and only CaO, K2O and Na2O would consume partial pressure of HCl gas, reducing the indium recovery reaction rate. The present study might provide important inspiration for indium recovery from waste LCDs via chloride volatilization process.