Purification of rare earth elements from obsolete HDD permanent magnets

Abstract

Neodymium (Nd), praseodymium (Pr), and dysprosium (Dy) are classified as rare earth elements (REEs), that are crucial components in the development of technologies such as wind turbines and hybrid vehicle batteries to address climate change. Despite their importance, the limited availability of these elements and China's predominant position in purification processes highlight the need to explore alternative sources. Waste electrical and electronic equipment (WEEE) presents itself as a promising secondary source of REEs, presenting higher concentrations than ores and aligning with circular economy principles for environmental conservation. Recycling obsolete neodymium-iron-boron (NdFeB) magnets consisting of 25% REEs has gained prominence. Instead of conventional recovery techniques that involve leaching in inorganic acids, incorporating organic acids as a sustainable substitute offers advantages such as selectivity and waste minimization. This study aims to develop a hydrometallurgical process for recovering Nd, Pr, and Dy from obsolete NdFeB magnets and then purification of the elements through solvent extraction with organic acid solutions.