Processing of discarded liquid crystal display for recovering indium

Different materials are used for manufacturing various parts of a cellular phone. Considering that a great number of mobile phones are being discarded every year, it is important to recover these materials and then recycle them in order to save resources. The primary objective of this work is therefore to find and suggest ways on how to recover various materials from discarded cellular phones for recycling. Much effort, for example, has been put in recovering and recycling tin oxide (ITO), a mixture of indium (III) oxide, (In ₂O₃) and tin(IV) oxide from the discarded liquid crystal displays (LCDs). Here we report a simple and cost-effective process, which includes a HCl treatment process for altering the structure of the indium (III) compound into a chloride-induced indium compound, in order to facilitate the vaporization of indium at a relatively low temperature. The experimental results indicated that 96.2 % of indium can be recovered from ITO, when the sample was heated at 973 K for 90 minutes. In addition, some thermodynamic calculations were also carried out in order to better understand the mechanism for chloride-induced vaporization of indium.