Recycling of Rare Earth Magnets with Sulfur Based Chemistries and High Temperature Processing

Abstract

Rare-earth(RE)-iron-boron permanent magnets are among the strongest permanent magnets available and power essential technologies, from wind turbines to hard disk drives. The production of the rare earth metal for these magnets currently involves significant greenhouse gas emissions and other environmental impacts. Additionally, the production of these metals is geographically complicated, as over 95% of rare earth metals are produced in China, which leads to supply-chain concerns and price fluctuations. Recycling of the rare earth elements is imperative to decrease net emissions and for the sustainability of RE-based magnets, but current magnet recycling is limited. In this work, sulfidation is investigated in the context of RE separation and recovery from RE-based magnets. Evidence of rare-earth separation and selectivity are presented, with insights into the underlying sulfidation mechanism involved for actual magnet processing.