Hydrometallurgical processes for the recovery of precious and critical metals from liquid crystal displays

In 2010 indium was identified by the European Commission as a critical raw material for its economic importance and the supply risk. This metal represents a component of many electronic equipment and therefore its request is high; this fact favors indium recycling. The present study has been carried within the European project FP7 308549 HydroWEEE Demo. It deals with the recovery process of indium from end-of-life liquid crystal displays (LCDs). We carried out a hydrometallurgical process that included a stage of LCD washing followed by metal leaching in a sulfuric acid solution using a cross-current design. The final step of the treatment consisted of zinc cementation that allowed to obtain the transfer in the solid phase of indium present in the leach liquor. The whole process reached an indium recovery efficiency > 90%, and thanks to the cross-current leaching a lower amount of acid was used compared to conventional leaching.