A green method for recycling materials from liquid crystal display panel

Abstract

In this study, a technology process including wet grinding, sieving and vacuum separation was proposed to recycle materials from waste liquid crystal display panel (LCDP). A wet crusher was used to break the glass and polarizing film of LCDP into granule first. Most liquid crystal molecules (94.10 wt. %) would be cleaned from LCDP under the impact of crusher and stayed in water. When the particle size of solid granule is less than 0.18 mm, the composition is pure glass, which accounted for 69.97 wt. % of the total granule. Pure polarizing film presents at more than 0.80 mm of particle size, which accounted for 11.47 wt. % of the total granule. The granule between 0.18∼0.80 mm, which contains glass and polarizing film bonded together, would be sent back to crusher to dissociate again. The glass part of LCDP contains indium of 219 ppm. Vacuum carbothermal reduction was employed to recycle indium from the glass part of LCDP. Based on the orthogonal optimization experiment, the optimal parameters were 950 °C, 30 min, 30 wt. % carbon adding amount and 1 Pa. Indium can be separated from the indium tin oxide (ITO) of glass part selectively. The recovery ratio of indium was 93 wt. %. During the physical process, all the valuable materials including indium, glass and organic materials can be recycled efficiently and eco-friendly, and there are no hazardous materials produced.