Separation and concentration of valuable and critical materials fromwasted LEDs by physical processes

Abstract

The generation of wasted LEDs is expected to grow in the coming years, raising the challenge of recyclingand recovering their valuable and critical materials. Due to the low concentration of these materials, thecurrent recycling processes available for LEDs have a significant recovery limitation. This study proposesan innovative, clean and effective physical method to segregate the valuable and critical materials intodifferent fractions while enhancing their concentration: particle size separation followed by electrostaticseparation. After the determination of the best electrostatic separation conditions (varying tension androtation) for each particle size, the final fractions were characterized by acid digestion and ICP-OES anal-ysis. The analysis revealed that the economically valuable elements gold, silver, copper and tin becameconcentrated in the conductive fractions (80.18%, 94.22%, 96.55% and 93.29% of their total recoveredmass, respectively), while the strategic critical elements, gallium, cerium and yttrium became concen-trated in the non-conductive fractions (96.15%, 100% and 95.20% of their total recovered mass, respec-tively). Despite some limitations imposed by the mass losses, this novel route may be important touncover new recycling alternatives, mainly for critical elements, and to improve the economic viabilityof the recycling routes.