Rare-Earth Elements Recovery from Nd-Fe-B Hard Magnets by Hydrometallurgical Processes

Abstract

In this study, a hydrometallurgical process was evaluated for the recoveryRecovery of Nd from a Nd-Fe-B magnet. Each leachingLeaching test was performed at the solid (weight) to liquid (volume) ratio of 1:50 and was mixed at 400 rpm at ambient temperatureTemperature. The effects of 3 different acids (HCl, HNO3, and H2SO4) on the extractionExtraction of Nd were investigated and H2SO4 was found to be more effective than other acid solutions. Under the optimal conditions, pregnant leachLeach solution was produced with H2SO4 for subsequent Nd precipitationPrecipitation testingTesting. Each precipitationPrecipitation test was carried out using 100 mL of feed solution mixed at 600 rpm at 25 °C. NaOH and H2C2O4 were used for Nd precipitationPrecipitation. The highest Nd was precipitated as Nd2(C2O4)3·10H2O with C2H2O4 at 20 min.