Cyphos IL 104 assisted extraction of indium and recycling of indium, tin and zinc from discarded LCD screen

The recycling of indium from E-waste is extremely useful due to concerns correlated with its limited supply in future. In the present work one of the phosphonium ionic liquid (PIL), Cyphos IL104 [tetradecyl-(trihexyl) phosphonium bis-(2,4,4-trimetylpentyl) phosphinate] diluted in toluene was used as an extractant to separate, extract and recover metals from discarded LCD screen. Factors affecting the solvent extraction behaviour of indium such as shaking time, acid/extractant concentration, temperature and chloride ion concentration of the aqueous phase were examined systematically. Saturation and recycling power of Cyphos IL 104 has also been determined. Optimized condition have been employed to recover indium, zinc and tin from the discarded LCD screen leach liquor containing In – 160 mg L−1, Sn – 494 mg L−1, Zn – 110 mg L−1, Fe – 2911 mg L−1, Al – 1231 mg L−1, Mn – 217 mg L−1, Ca – 3132 mg L−1 and Sr – 311 mg L−1. The number of stages required for extraction and stripping were determined from the McCabe-Thiele diagrams and confirmed by counter current studies carried out with discarded LCD leach liquor. It was found that quantitative extraction of In, Zn and Sn is accomplished in two stages at A/O = 3/2, using 0.1 mol L−1 Cyphos IL 104. In, Zn and Sn were stripped quantitatively with selective stripping agents in two stages at O/A = 3/2. After separation the three metals were recovered by precipitation and calcination as metal oxide/sulphide and were characterized by FE-SEM, EDX and XRD techniques.