Novel mechanical pre-treatment methods for effective indium recovery from end-of-life liquid-crystal display panels

This study investigated the suitability of mechanical pre-treatment
methods (mechanical abrasion and treatments of heat, laser, and plasma)
together with a hydrometallurgical process comprising leaching and
cementation for recovering indium from used LCD screens. With mechanical
abrasion pre-treatment, 96.2% of indium was recovered and black mass
with an indium content of 15.6 wt percent was obtained. Following the
mechanical recovery, sulfuric acid leaching was used to produce
leachates with an indium purity ranging from 86.3 to 98.0% with an
88.7–100% yield for indium. Indium was recovered from the leachate by
cementation with zinc powder, but also the impurity metals were
cemented. The suggested mechanical pre-treatment involving the indium
recovery process was seen as a viable option since it dramatically
reduces the mass fed to the hydrometallurgical purification process (by
roughly a factor of 1000), and up to 97.1% pure indium product can be
obtained with a simplified process. The purity of the indium product can
be further increased by additional purification steps.