Extraction of Rare Earth Elements from Permanent Magnet Scraps by FeO–B2O3 Flux Treatment

Abstract

In order to recover the rare earth elements (REEs) from neodymium permanent magnet scraps, Fe2O3, B2O3, and FeO–B2O3 fluxes were designed to extract the REEs. The REEs containing oxides were successfully separated from the Fe-based metals at the temperatures of 1,673, 1,773, and 1,823 K. A mechanism for extraction of REEs has been proposed based mainly on the experimental observations using the flux of FeO·B2O3 at 1,573 K. Effects of temperature and reaction time were also investigated. The experimental results have shown that increasing temperature and prolonging holding time help the reduction of B2O3 contents in the oxide phase. The FeO–B2O3 fluxes show better extraction efficiency. The purity of rare earth oxide was 98.4 % produced by 2FeO·B2O3 and the extraction ratios were higher than 99.5 % after the FeO–B2O3 fluxes treatment.