Selective extraction and separation of REEs from NdFeB magnets scrap using co-chlorination and water leaching

Abstract

An approach of co-chlorination followed by water leaching to achieve the selective extraction of rare earth elements (REEs) from NdFeB magnets scrap (scrap) was studied. Co-chlorination refers to the synergistic effect of direct and indirect chlorination reactions. The feasibility of direct and indirect chlorination was explored from both theoretical and practical standpoints. The transformation between NdCl3 and NdOCl during the chlorination roasting process was discovered by X-ray diffraction (XRD) analysis combined with Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS) as well as chemical analysis. The formation of NdOCl was prevented by regulating FeCl3·6H2O dosage, chlorination temperature and chlorination time, then the negative impact from the hydrolysis of NdOCl was avoided. As a result, the complete chlorination of REEs was successfully achieved by using co-chlorination and water leaching. The results showed that 96.51% REEs and 64.29% Co can be synchronously extracted into the leaching solution under appropriate conditions. After the separation of REEs and iron, 92 wt% iron oxide was obtained. This work offers an effective method for recovering REEs from NdFeB magnets scrap.