An Acid Free Electrified Process for Recycling Rare-Earth Elements from NdFeB Magnet Waste

Recycling of rare-earth elements (REEs) from NdFeB magnets is an important strategy to mitigate the risks associated with the REE supply chain. In this article, we propose an electrochemical process to recover REEs wherein all the reagents required for both leaching of REEs as well as the precipitation are generated in situ electrochemically. A three compartment electrochemical reactor was used in which a rare-earth containing salt along with an additive salt, ammonium sulfamate, was fed into the middle compartment. Upon electrolysis, the salts were split into acid and rare-earth hydroxides. The acid generated in the anolyte compartment was used to leach the NdFeB magnet waste. The rare-earth hydroxides were collected in the catholyte compartment and calcined to obtain rare-earth oxides. More than 95% of REEs and cobalt were extracted into the solution, and more than 85% of iron was removed as Fe(OH)3 precipitate in the same step. Subsequently, the leachate was oxidized and neutralized to remove more than 99% of iron. By using electrons as green reagents, this process combines leaching and precipitation in a single reactor enabling process intensification. The leachate produced at the end is rich in REEs and can be fed again into the middle compartment, forming a completely closed-loop process. Overall, the process consumes no acid, only electricity, ammonium hydroxide for neutralization, and an additive salt, ammonium sulfamate.