Rare Earth Element Recycling from Energy-Transition E-Waste: A Review of Thermal and Electrothermal Processes

Research on the recovery and recycling of rare earth elements (REEs) from waste electrical and electronic equipment (e-waste) is essential to address their limited availability and the vulnerabilities associated with global supply chains. Among the various REE recycling strategies, this work focuses on thermal treatments for REE recovery from specific e-waste streams associated with energy-transition technologies, including waste printed circuit boards (WPCBs), permanent magnets, and Ni–MH batteries. These waste streams are of particular interest because of their relevance to power electronics, electric mobility, and energy-storage applications, highlighting the need for effective end-of-life management solutions. Conventional thermal recovery processes offer significant potential for industrial-scale implementation; however, they also present major challenges, including high energy consumption, elevated operating costs, variable recovery efficiency, and environmental impacts. To address these limitations, this review investigates the adoption of electrothermal technologies as alternative heating solutions capable of improving process efficiency while reducing emissions and the overall carbon footprint, thereby contributing to more sustainable REE recycling practices aligned with green engineering principles. Several categories of electrothermal furnaces are reviewed and compared in terms of energy efficiency, achievable temperature range, temperature uniformity, cost, and suitability for industrial-scale REE recovery. In particular, this work identifies induction heating as a promising and sustainable alternative for future industrial recycling systems, especially for the melting treatment of NdFeB magnets recovered from electric motors and generators.