Recovery of rare-earth element from rare-earth permanent magnet waste by electro-refining in molten fluorides.

REEs are selectively separated from REPM wastes. The separated REEs are recycled in the form of rare-earth metals which can be directly applied in industry. Forming anode channels make the separation of REEs in the inside of REPM wastes feasible. • Rare-earth metal was directly recycled from REPM waste. • Forming anodic channels facilitated the oxidation of rare-earth elements inside the REPM waste. • The formation parameter and process of channels were proposed. Tens of thousands of tons of rare-earth permanent magnet (REPM) wastes are produced worldwide every year. The recovery of rare-earth elements from the wastes can effectively reduce the exploitation of rare-earth minerals. The recovery of neodymium and praseodymium from a REPM waste is investigated by electrolysis in molten LiF-CaF 2 where no anode gas releases, making the process environmentally attractive. Neodymium and praseodymium are selectively oxidized from the REPM waste and transformed into rare-earth ions. To facilitate the oxidation of rare-earth elements inside the REPM waste, we intended to make REPM electrode form channels by oxidation of Nd-Pr and Nd 2 Fe 14 B alloys. By analyzing the microstructure of REPM electrode after forming channels, it can be found that the channels provide continuous transport access of the electrolyte to the inside of the REPM electrode. The separation rates of Nd and Pr increase with increasing current, while the rate of oxidation reaction is proportional to current. In addition, the oxidation of Fe initially occurs at the inside of the REPM electrode where rare-earth elements have been first depleted. The separated rare-earth ions are directly prepared as rare-earth metals at the cathode by electrolysis, leaving the porous Fe 2 B alloy and metallic Fe. [ABSTRACT FROM AUTHOR]