Selective and efficient extraction of Nd from NdFeB magnets via ionization in LiCl-KCl-CdCl2 melt

Abstract

The growing popularity of NdFeB magnets has created a demand for sustainable Nd recycling processes with fewer byproducts and higher extraction efficiencies. To address this need, we herein studied the extraction of Nd from NdFeB magnets via selective ionization in CdCl2-LiCl-KCl at 773 K. When the CdCl2 content was sufficiently large to completely ionize Nd into Nd3+ > 99% of Nd was selectively extracted into the salts within 2 h, while Fe and B remained in the solid phase. The microstructural and compositional changes of the magnet and salts were examined by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and by inductively coupled plasma-optical emission spectrometry. In the presence of CdCl2, the magnet was naturally fragmented and pulverized. Correlations between CdCl2 content and cyclic voltammetry data (peak current density and peak potential) were established and validated to monitor the reaction progress on-line, and the maximum correlation errors for peak current density and peak potential were found to be less than 8.33% and 16.1%, respectively. Finally, the results of this study were combined with those of previous works to propose a novel Nd recycling process based on molten salt usage. (C) 2020 Elsevier B.V. All rights reserved.