Overview: DARPA/DSO has issued an ARC Opportunity inviting submissions of abstracts for innovative exploratory research concepts in the technical domain of Rare Earth Element (REE) separation methodologies (https://www.darpa.mil/ARC). ARC Opportunities are designed to allow an individual researcher the opportunity and time to focus on nascent, paradigm-shifting ideas for national security applications. This SPREE Opportunity is issued under the umbrella ARC Exploration Announcement (EA), DARPA-EA-23-01.

Background: REEs comprise 17 elements, including scandium, yttrium, and the lanthanide series. REEs are used in a range of products and manufacturing processes, including permanent magnets, catalysts, fiber optics, and phosphor displays, which are critical to wind turbines, cell phones, and electric vehicles, among other modern technologies. However, REE extraction, separation, and purification from a complex feedstock can be environmentally degrading, energy inefficient, and difficult to permit in the U.S. From the mid-1960s to the mid-1990s, the U.S. was the world’s major supplier of REEs. Today, the U.S. imports nearly 100% of REEs used in commercial products and exports some domestically mined REE minerals for economic processing overseas. This dependence on foreign sources for processing and purification represents a significant vulnerability for the U.S. supply chain, which could be mitigated by developing a domestic manufacturing industry to extract and purify REE resources within the United States. However, widely utilized methods of extraction and separation of REEs, especially from each other, can be inefficient, energy- intensive, complex, and/or produce sizeable amounts of hazardous waste due to the use of toxic reagents and solvents, resulting in domestic permitting challenges due to predictedenvironmental impacts. As a result, there is a significant commercial barrier for domestic mining and refining of REEs.