https://phys.org/news/2018-11-shortening-rare-earth-chain-recycling.html

As reported in Waste Management, instead of using acid extractants to dissolve the REs trapped in the spent lamps, the Kanazawa team turned to chelator chemistry. Chelators—organic compounds containing elements such as N or O—bond to metals through electron donation. This allows them to gently leach out REs from the solid mass of a spent phosphor, without the need for strong acids.

"An ideal type of chelator compound is known as amino-polycarboxylates," explains study co-author Ryuta Murase. "These are already used to remove toxic metals from solid waste. We found they were also very efficient at extracting REs from spent phosphors—especially yttrium and lanthanum, which are used in the more chemically reactive red phosphors. The best performance was by the chelator EDTA, probably because it forms the strongest complexes with the metals."