Sustainable separation of rare earth elements from wastes

Rare earth elements (REEs) are indispensable in modern technologies, but their supply chain faces challenges due to limited geographical availability and political difficulties. Recycling REEs from industrial waste provides a sustainable alternative to mining, promoting a circular economy and reducing environmental impacts. The mainstay approaches for REE recovery, hydrometallurgical and pyrometallurgical methods, can be inefficient, consuming high energy and generating large aqueous and acid waste streams. Here, we introduce flash Joule heating (FJH) combined with chlorination (FJH-Cl 2 ) as an efficient method for REE separation and recovery by capitalizing on the free energies of formation (ΔG form ) of the metal chlorides and the boiling points of those metal chlorides. FJH-Cl 2 enables high-purity (>90%) and high-yield (>90%) REE recovery from waste magnets in a single step. Life cycle assessment and techno-economic analysis show that this process reduces the number of steps by 3× while reducing energy consumption by 87%, greenhouse gas emissions by 84%, and operating costs by 54% while eliminating water and acid use by 100% compared to traditional methods. This offers an environmentally friendly and economically viable pathway for sustainable REE recycling and recovery.