Selective leaching of indium from spent LCD screens by siderophore desferrioxamine E

Given the criticality of indium (In), spent LCD screens can represent a viable secondary resource of In. In this work, an innovative and alternative technology to selectively leach In from spent LCD screens using a microbial chelating agent, desferrioxamine E (DFOE), was developed. Indium was concentrated from spent LCD screens by implementing an adapted pre-treatment procedure, allowing the isolation of an indium-rich glassy fraction. During leaching, the competition between Aluminum (Al) and In for complexation with DFOE leads to the precipitation of In(OH)3 at low DFOE concentration (12-240 µM). After adjusting the optimal conditions (fraction size: 0-36 μM, pH 5.5, S/L ratio: 1 g/L, room temperature), the In leaching yield reached 32%, ten times higher than Al over 90 days with 5 mM DFOE. Thus, selective leaching of In, while mitigating the influence of competing element Al, makes it possible to achieve a high In recovery by extending leaching time. This is the first attempt to selectively leach In by a selected siderophore from end-of-life (EoL) products with high concentrations of non-targeted elements (i.e. Al, Si, and Ca). This work shows good potential to generate indium-rich leachates that can be further processed by the GaLIophore technology for indium refinery.