Phoenix Tailings: Cleaning Up Rare Earth Mining

By Abdul Ahad NazakatReviewed by Laura ThomsonMar 18 2026

Rare earth elements (REEs) are not especially rare in geological terms. The challenge is processing them cleanly and at scale. That challenge has been ceded almost entirely to China for decades. The International Energy Agency's Critical Minerals Outlook 2024 reports that China accounts for roughly 60 % of global REE mining output and approximately 91 % of refining and separation capacity.¹ This concentration poses supply chain vulnerabilities for industries from electric vehicles and wind turbines to defense systems.

Against this backdrop, Phoenix Tailings, a Massachusetts-based company co-founded by MIT alumni, has built a technology platform designed to produce rare earth metals domestically, from mining waste, without the hazardous chemical processes that define the conventional industry.

Image Credit: bqmeng/Shutterstock.com

The Environmental Costs of Conventional REE Refining

The environmental record of conventional REE production is well-documented. A 2022 life cycle assessment published in MRS Bulletin found that leaching and precipitation steps in standard REE refining require large volumes of hydrochloric and sulfuric acid, whose production contributes significantly to environmental burden across the process chain.

Flotation tailings, generated at rates of tens of tons per ton of rare earth oxide, are typically discharged into open ponds. At Bayan Obo, the world's largest REE deposit, the Baotou tailings pond holds material contaminated with radioactive thorium at a mean concentration of 5 %, with no liner system or vegetation cover, and poses ongoing toxicity risks to the Yellow River downstream.²

A comprehensive 2025 review in the Journal of Hazardous Materials by Han, Cui, Zhang, and colleagues documented that abandoned REE tailings are characterized by low pH, low organic matter, and low fertility - conditions that severely impede natural ecological recovery and require active remediation.³ The review identified ammonium sulfate leaching as a particular driver of widespread soil acidification and groundwater contamination in southern China's ion-adsorption REE mining regions.³

Phoenix Tailings: Technology and Approach

Phoenix Tailings was co-founded in 2018 and describes its mission as building the first fully clean mining and metals production company. Its core technology uses electrochemistry and advanced materials science to recover critical metals from mining tailings and other industrial byproducts, without the acid-heavy chemistry of conventional refining.⁴

In practice, feedstock rich in rare earth metals is processed through a proprietary electrochemical system that collects pure metal on an electrode, generating minimal residual waste. When powered by renewable electricity, the process operates with no direct carbon emissions and no toxic chemical byproducts.⁵ 

The platform encompasses two integrated capabilities:⁶

• Separation - Isolating individual light and heavy rare earth oxides from ore concentrates
• Metallization - Converting those oxides into pure metals and alloys using stabilized chemistries and automated systems.

Metallization has historically been a critical bottleneck in Western supply chains, even where domestic separation exists, and converting oxides to magnet-grade metal has remained almost entirely dependent on Chinese capacity.

Video Credit: Phoenix Tailings/YouTube.com

Commercial Operations

Phoenix Tailings has a Woburn, MA site serving as the R&D hub, while its Burlington, MA site supports process scale-up. The most significant milestone came in October 2025, when the company opened a rare-earth metallurgy facility in Exeter, New Hampshire, described as one of the largest of its kind in the Western world and operating with zero reliance on Chinese inputs, equipment, or technology.⁷

Initial production capacity is 200 tons per year of light and heavy rare earth metals, principally neodymium-praseodymium (NdPr) and dysprosium-iron alloy (DyFe), with a planned scale-up pathway to more than 1,000 tons per year, a level the company states could supply the entire US defense industrial base's rare earth requirements.⁷

The Exeter facility accepts feedstock from mines, recycled materials, coal fly ash, and other unconventional sources, making it the first standalone US rare-earth refinery capable of processing such a broad range of inputs.⁸

A 2025 review in the Journal of Resources, Conservation and Recycling concluded that tailings valorization of this kind reduces the environmental footprint of mining operations while providing cost-effective means to extract valuable by-products.⁹

Investment and Strategic Context

Phoenix Tailings closed a Series B round totaling $76 million in 2025, with participation from Builders Vision, Yamaha Motor Ventures, Escape Velocity, and Presidio (the venture arm of Sumitomo Corporation).⁸

In early 2026, the company secured an additional $40.2 million in strategic capital to accelerate production.¹⁰ The company also holds investment from In-Q-Tel (IQT), a US government-affiliated fund focused on technologies of national security relevance.⁷

The strategic urgency is clear: China's progressive tightening of export controls on rare earth elements from late 2024 onward has raised the cost of dependence on a single refining geography. In 2025, the IEA noted that, with China controlling 91% of global separation and refining output, even mines operating outside China face midstream vulnerabilities.¹ Phoenix Tailings' vertically integrated model, spanning feedstock sourcing through finished metal and alloys, directly targets that structural gap.

In December 2025, the company was also selected to receive $1.6 million in federal funding from the Department of Energy to develop ligand-based extraction technology for critical minerals from industrial wastewater, extending its circular economy model to brine streams from oil, gas, and mining operations.¹¹

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Considerations and Limitations

Some limitations are worth noting. Phoenix Tailings' environmental claims apply only to its own refining operations; company representatives have stated that it is still working to account for upstream mining and preprocessing steps that occur before feedstock reaches its facilities.¹²

Analysts at Rare Earth Exchanges, in their coverage of the Exeter opening, also cautioned that the US remains years from full supply chain resilience, requiring sustained investment in infrastructure, permitting reform, trained labor, and midstream financing that no single company can provide alone.¹³

Conclusion

Phoenix Tailings has built something largely absent from Western rare-earth supply chains: a commercially operating metallization facility on US soil, independent of Chinese inputs, processing materials that would otherwise remain environmental liabilities.

Its electrochemical approach avoids the acid-heavy, radioactive-waste-generating processes of conventional refining, and its feedstock flexibility, which draws on tailings, recycled materials, and industrial byproducts, reflects sound circular-economy thinking.

The technical and environmental challenges of REE production are real and ongoing. What Phoenix Tailings offers is one functioning piece of an infrastructure the sector has long lacked, and a model that future investment in the space can build from.

References and Further Reading

1. International Energy Agency. With New Export Controls on Critical Minerals, Supply Concentration Risks Become Reality. IEA Commentary, October 2025. https://www.iea.org/commentaries/with-new-export-controls-on-critical-minerals-supply-concentration-risks-become-reality
2. Zapp, P., Schreiber, A., Marx, J. & Kuckshinrichs, W. Environmental impacts of rare earth production. MRS Bulletin 47, 267–275 (2022). DOI: https://doi.org/10.1557/s43577-022-00286-6
3. Han, Y.-H., Cui, X.-W., Zhang, Y., Zhang, H. & Chen, Z. Environmental impacts of rare earth elements mining and strategies for sustainable management: A comprehensive review. Journal of Hazardous Materials 500, 140400 (2025). DOI: https://doi.org/10.1016/j.jhazmat.2025.140400
4. Phoenix Tailings. About Phoenix Tailings. phoenixtailings.com, 2025. https://phoenixtailings.com/about
5. MIT News Office. Startup Turns Mining Waste into Critical Metals for the U.S. November 2024. https://news.mit.edu/2024/startup-phoenix-tailings-turns-mining-waste-into-critical-metals-1108
6. Phoenix Tailings. Innovation: Technologies Behind a Stronger America. phoenixtailings.com, 2025. https://phoenixtailings.com/innovation
7. Phoenix Tailings / Business Wire. Phoenix Tailings Opens Cutting-Edge U.S. Rare Earth Metallization Facility Entirely Independent From China. October 23, 2025. https://www.businesswire.com/news/home/20251023800456/en/Phoenix-Tailings-Opens-Cutting-Edge-U.S.-Rare-Earth-Metallization-Facility-Entirely-Independent-From-China
8. Phoenix Tailings / Business Wire. Phoenix Tailings Closes on Additional $33M in Funding, Bringing the Round up to $76M. April 30, 2025. https://www.businesswire.com/news/home/20250430735778/en/
9. Hajdu-Rahkama, R. & Kinnunen, P. Tailings valorisation: Opportunities to secure rare earth supply and make mining environmentally more sustainable. Journal of Cleaner Production 520, 146147 (2025). https://www.sciencedirect.com/science/article/pii/S0959652625014970
10. Phoenix Tailings. Phoenix Tailings Secures $40.2 Million in Strategic Capital to Accelerate U.S. Rare Earth Metals Production. 2026. https://phoenixtailings.com/press/phoenix-tailings-secures-40-2-million-in-strategic-capital-to-accelerate-u-s-rare-earth-metals-production
11. Phoenix Tailings / Business Wire. Phoenix Tailings Selected to Receive $1.6 Million in Federal Funding for Technology to Extract Critical Minerals From Wastewater. December 4, 2025. https://www.businesswire.com/news/home/20251204539236/en/Phoenix-Tailings-Selected-to-Receive-1.6-Million-in-Federal-Funding
12. Hoplamazian, M. One of the Country's Few Rare Earth Processing Plants Opens in Exeter. New Hampshire Public Radio, October 30, 2025. https://www.nhpr.org/nh-news/2025-10-30/one-of-the-countrys-few-rare-earth-processing-plants-opens-in-exeter
13. Rare Earth Exchanges. Phoenix Tailings Ignites the U.S. Rare Earth Revolution. October 23, 2025. https://rareearthexchanges.com/news/phoenix-tailings-ignites-the-u-s-rare-earth-revolution/

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