Liberation and separation of valuable components from LED modules: presentation of two innovative approaches

The rapid development of light-emitting-diode (LED) technology is attributed to its superiority over light sources of earlier generations. Although LED lamps, compared to compact fluorescent lamps, are considered less harmful to the environment, there is still no efficient solution to deal with them at the end of their lifecycle. The first part of the study provides a detailed characterisation of LED lamps, focusing on their most interesting component: the LED module. LED packages attached to the module are highly enriched with Ga, In, Pd, Ag, Au, Sr, Y, Ce, Eu, Gd, and Lu, with the content of each element varying greatly depending on the LED technology. In the second part of this research, two new approaches for liberation and concentration of valuable components from LED modules are presented and compared: a chemical route and a thermal route. The chemical treatment leads to a highly selective separation of LED chips and encapsulation. Enrichment factors up to about 125 are achieved, and a concentrate is obtained containing approximately 14 wt% of the aforementioned valuable components. However, the process requires aromatic solvents, which are viewed as toxic. The thermal treatment results in separation of the aluminium heat sink from all other components of the LED module. Enrichment is approximately ten times lower, but the approach is technically feasible.