New projects could lift U.S. rare earth output and meet much of future magnet demand, but costly processing, uncertain ramp-up, and limited refining capacity still stand between domestic resources and a secure mine-to-magnet supply chain.
Review: Rare earth production in the United States: A concise review of resource development and commercial processes. Image Credit: Tang Yan Song / Shutterstock
A recent review published in the journal Minerals Engineering examines the current state of rare earth element production in the United States (US) and the technologies needed to strengthen domestic supply chains.
The review assesses major mining projects, processing and separation technologies, secondary feedstocks, recycling opportunities, and key research needs. Overall, the review finds that US rare earth production capacity is expanding, but limited refining and metal-production capabilities remain major barriers to establishing a fully integrated domestic supply chain.
Building a Stronger Domestic Rare Earth Supply Chain
Rare earth elements (REEs) comprise 17 elements, including the 15 lanthanides, scandium, and yttrium. Although these elements are relatively abundant in the Earth’s crust, extracting and separating them economically remains challenging. Their similar chemical properties make individual separation particularly difficult. As a result, substantial geological resources do not necessarily translate into a reliable supply of refined rare-earth materials.
The authors examine current and near-term rare earth production in the United States. They identify nine major mining and processing projects selected using criteria that included being in operation or expected to operate within five years, although several project timelines remain uncertain.
The analysis evaluates resource estimates, mineralogy, beneficiation, extraction, purification, REE separation, refining, and emerging recovery routes. It also considers secondary feedstocks, including coal ash, mine tailings, monazite byproducts, industrial waste, and end-of-life magnets.
The review highlights a major gap in the US supply chain. The country has significant rare earth resources but limited domestic processing and refining capacity. Most commercial projects currently produce mixed rare-earth oxide concentrates, and further separation and refining are required to produce individual high-purity oxides and metals for downstream applications. This makes domestic processing and refining essential for building a more integrated and resilient supply chain.
A Comprehensive Review of U.S. Rare Earth Production and Processing
The authors compiled information from United States Geological Survey reports and databases, pre-feasibility and feasibility studies, technical reports, company investor presentations, and scientific literature. They noted that feasibility studies and investor presentations can carry purpose-driven biases or lack technical transparency, and used scientific literature where possible to support their interpretations.
The review selected nine major domestic operations. Each project involved primary rare earth element mining or processing, had the potential to contribute significantly to US production, and met the authors’ criterion of being operational or expected to operate within five years.
They compared resource size, grade, mineralogy, proposed processing methods, production capacity, and development status. The analysis covered the full processing chain, including crushing and grinding, gravity and magnetic separation, froth flotation, leaching, ion exchange, solvent extraction, precipitation, calcination, metallothermic reduction, and molten salt electrolysis.
The analysis also assessed secondary resources and recycling routes. Coal ash, phosphogypsum, acid mine drainage, industrial waste, mine tailings, electronic waste, and permanent magnet scrap were considered potential supplementary sources. This approach provided a broader assessment of conventional mining and alternative pathways to strengthen the domestic rare earth supply.
U.S. Rare Earth Resources, Processing Advances, and Production Outlook
Across the seven evaluated projects, the analysis confirms that the United States has a substantial rare earth resource base, but resource availability alone does not guarantee a secure domestic supply.
Resources total about 4.2 billion metric tons, containing approximately 12.6 million metric tons of total rare earth oxides (TREO). Light rare earths dominate these resources, while neodymium-praseodymium (NdPr) oxides account for about 19.5% of the estimated inventory.
These findings therefore highlight a key distinction between having large deposits and developing economically viable sources of refined rare earth materials. The projects also demonstrate that rare earth processing must be tailored to deposit characteristics. Mountain Pass uses flotation and downstream chemical processing for bastnaesite ore, while other projects propose approaches such as heap leaching, dense media separation, magnetic separation, continuous ion exchange, and ion chromatography.
The paper identifies individual REE separation as a major processing bottleneck. Solvent extraction remains the dominant commercial approach, but the similar chemical properties of neighboring rare earths require numerous separation stages. RapidSX is being developed to accelerate mixing and phase separation and potentially reduce equipment footprint and capital costs, while continuous ion exchange and ion chromatography provide alternative continuous separation routes.
The projected development pipeline indicates that domestic production could expand significantly, with planned projects potentially raising annual TREO production to about 46,700 metric tons by 2030.
Current production, together with planned White Mesa expansion, could raise NdPr oxide output to about 8,600 metric tons annually, potentially meeting around 68.5% of projected 2030 domestic demand for permanent magnets.
Under a more optimistic scenario in which Mountain Pass, White Mesa, Round Top, and Bear Lodge reach 100% design capacity, production could approach 10,840 metric tons, or about 86% of projected demand, although the authors caution that newly commissioned projects are unlikely to reach full capacity immediately.
These projections also depend on project financing, permitting, commissioning, and successful production ramp-up.
Advancing a Secure and Sustainable U.S. Rare Earth Supply Chain
Taken together, these developments indicate that the United States is moving toward a more diverse and integrated rare earth industry, but the transition remains incomplete. Domestic resources are substantial, and projects across the country could significantly increase future production. However, supply security depends on more than opening new mines.
Rare earth development is capital intensive, and radioactive components in some deposits, market volatility, and lengthy development timelines can complicate project economics and schedules. Established methods such as solvent extraction and ion exchange provide a commercial foundation, while emerging technologies could improve separation efficiency and potentially reduce processing steps, reagent use, equipment footprint, or costs, depending on the technology.
Secondary resources offer another opportunity to strengthen supply. Coal ash, mine tailings, phosphogypsum, industrial waste, electronic waste, and discarded permanent magnets could supplement primary production, although low rare earth concentrations, variable feedstocks, and high processing costs can limit economic viability.
Recycling remains especially challenging, despite the comparatively high concentrations of valuable rare earths in permanent magnets and some other end-of-life products.
Overall, the review frames domestic rare earth production as a systems challenge that requires continued investment in processing, refining, secondary-resource recovery, and recycling.
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