(101a) Circular Processing of Rare Earth Elements from End-of-Life Products

The rare earth elements (REEs), consisting of the lanthanide series, scandium, and yttrium, are a group of elements necessary for the manufacturing of modern everyday technologies, as well as technologies necessary for national defense [1, 2]. Currently, the United States contributes roughly 15% of the globally mined REEs yet has minimal processing capabilities, resulting in nearly all mined materials being exported for separation and refining [1]. We propose recovering REEs from end-of-life (EOL) products to enhance the U.S. supply chain. Targeting EOL products has several benefits over traditional mining operations. First, EOL products can harbor REEs at concentrations higher than those found in other unconventional and secondary sources of REE that are currently being pursued as potential domestic feedstocks, including some mineral ores. Second, targeting EOL products circumvents the radioactive waste challenges associated with some traditional REE ores (and therefore mining and mineral processing operations), where radioactive elements—particularly thorium—can co-occur with REEs [3].

In this work we utilize superstructure optimization to identify the optimal processing pathways for REE recovery from EOL products containing rare earth permanent magnets (REPM). First, a master flowsheet is constructed that encompasses processing alternatives for recovering REEs as either mixed or individual rare earth oxides (REOs) and recovering iron, the main constituent of permanent magnets, as iron oxide. We then formulate a multi-objective optimization problem to find pathways that maximize the net present value (NPV) and minimize LCA metrics. The framework is designed to simultaneously process multiple EOL products containing REPM, including motors from electric and hybrid electric vehicles and hard disk drives. Our model considers capacity expansion and process flexibility to account for yearly variations in the types and quantities of available feedstocks.

References:

1. T. Lopez, “DOD looks to establish ‘mine-to-magnet’ supply chain for rare earth materials”, (2024). https://www.defense.gov/News/News-Stories/Article/Article/3700059/dod-looks-to-establish-mine-to-magnet-supply-chain-for-rare-earth-materials/, Accessed: 2025-03-20.
2. J. Smith, M. E. Riddle, M. R. Earlam, C. Iloeje, D. Diamond, “Rare earth permanent magnets supply chain deep dive assessment”, (2022).
3. Park, C. L. Tracy, R. C. Ewing, “Reimagining US rare earth production: domestic failures and the decline of US rare earth production dominance – lessons learned and recommendations”, Resources Policy. 85:104022 (2023).

Acknowledgments

This effort was funded by the U.S. Department of Energy’s Process Optimization and Modeling for Minerals Sustainability (PrOMMiS) Initiative, supported by the Office of Fossil Energy and Carbon Management’s Office of Resource Sustainability.

Disclaimer

This project was funded by the Department of Energy, National Energy Technology Laboratory an agency of the United States Government, in part, through a support contract. Neither the United States Government nor any agency thereof, nor any of their employees, nor the support contractor, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.