Enrichment of indium tin oxide from colour filter glass in waste liquid crystal display panels through flotation

Flotation is used to enrich indium tin oxide from the colour filter glass of waste liquid crystal display panels. Contact angle measurement and infrared spectroscopy analysis indicated that colour filter contained hydrophobic methyl groups and aromatic ring. Crushing experiment and backscatter imaging analysis revealed that the colour filter with indium tin oxide almost separated from the glass substrate with size fraction of −0.032 mm. The proportion of particles in the −0.032 mm fraction increased with increasing grinding time. A sufficient dissociation was found between the colour filter with indium tin oxide and the glass substrate, and the indium content in the fine size fraction also increased. Moreover, the indium content, indium tin oxide concentrate yield and indium tin oxide recovery increased with decreasing feed size. The indium content of the indium tin oxide concentrate reached 0.61%, the indium tin oxide recovery peaked at 85.21% and the enrichment ratio was 16.6 in particles with size below 0.025 mm. Furthermore, the indium content, indium tin oxide concentrate yield and indium tin oxide recovery increased with increasing grinding time. After 80 min of grinding, the indium tin oxide recovery peaked at 92.51%, the indium content of the indium tin oxide concentrate reached 0.60% and the enrichment ratio was 18.4.