Guide
From oxide to metal: why rare earth metallization is the US bottleneck
Rare earth metallization is the step that reduces separated oxides to metal and casts the metal into the alloy that magnet makers use. It is the thinnest part of the US chain: the Department of Energy found no US metal refining in 2022, and a 2026 review calls reducing oxide to metal the main commercial bottleneck for an integrated chain of metals and magnets.
MP Materials has made NdPr metal at Independence since Jan 2025, Phoenix Tailings reports a 200 t/yr plant in New Hampshire, and USA Rare Earth and REalloys are running or building alloy and metal capacity. China refined about 90% of the world's rare earth metal in 2020 (DOE).
Verified through Oct 1, 2026
At a glance
- Main routes
- Molten-salt electrolysis (Nd, Pr, DyFe) and calcium reduction (Dy, Tb, Y, Gd)
- Feed
- Separated oxide: 1.18 kg of NdPr oxide for 1 kg of NdPr metal (DOE)
- Products
- NdPr metal, ferrodysprosium, then NdFeB magnet alloy
- Main hazard
- Hydrogen fluoride in the fluoride routes (OSTI)
- Next guide
- How rare earth magnets are made
- DOE finding
- 2022No rare earth metal refining in the US
- China's metal refining share
- 90%2020 estimate (DOE)
- Electrolysis energy per tonne of Nd
- 12 to 30 GJAgainst 0.5 to 2.5 GJ for calcium reduction (OSTI)
- Phoenix Tailings capacity
- 500 t/yr200 t/yr built (company-reported)
What is rare earth metallization, and why is it the US bottleneck?
Rare earth metallization turns separated oxides into metal and alloy, usually by molten-salt electrolysis or reduction with calcium. It is the US bottleneck because the oxides are very stable, the common routes use toxic hydrogen fluoride and a lot of energy, and few US plants exist; the Department of Energy found none in 2022.
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Start with separated oxide
NdPr oxide, dysprosium oxide and other products arrive from the separation step at more than 99% purity. About 1.18 kg of NdPr oxide is needed for each kilogram of NdPr metal (DOE).
Output Oxide feed
In the US
- Producing: MP Materials oxide from Mountain Pass
- Plant operating: Energy Fuels oxide from White Mesa
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Prepare the feed
Rare earth oxides are so stable that most routes convert them to fluorides first, which needs hydrogen fluoride, an extremely toxic reagent. Electrolysis can instead dissolve the oxide in a molten fluoride bath.
Output Rare earth fluoride, or oxide in a fluoride bath
-
Reduce the oxide or fluoride to metal
In electrolysis, oxide dissolves in a molten fluoride salt above 850 °C and an electric current deposits liquid metal at a cathode. In calcium reduction, calcium strips the fluorine from a rare earth fluoride at about 900 °C.
Output Liquid metal, cast into ingots
In the US
- Plant operating: MP Materials electrowinning at Independence
- Plant operating: Phoenix Tailings molten-salt electrolysis, Exeter
- Plant operating: REalloys Euclid, company-reported
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Alloy and cast
The metal is melted with iron and boron and strip cast into thin strips; dysprosium is added as ferrodysprosium. The result is the NdFeB alloy that a magnet plant grinds into powder.
Output Magnet alloy strips
In the US
- Plant operating: MP Materials strip casting at Independence
- Plant operating: USA Rare Earth strip casting at Stillwater
- Korean Metals Plant Energy Fuels, South Korea (outside the US)
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Hand off to the magnet plant
Alloy and powder are normally made next to the magnet plant, because the fine powder reacts with air and can ignite, which makes it hard to ship (DOE).
Output Alloy for the magnet step
In the US
- Plant operating: MP Materials Independence is integrated
- Plant planned: Vulcan Elements metal making planned
Marker: ProducingPlant operatingPlant planned
Sources: the OSTI review for the chemistry and temperatures, the Department of Energy supply chain assessment for yields and handling, and MP Materials' 10-K for 2025 for the Independence process steps.
How is rare earth metal made?
Rare earth metal is made by molten-salt electrolysis or by metallothermic reduction. Electrolysis in a fluoride bath produces neodymium, praseodymium and dysprosium-iron alloy, and calcium reduction of fluorides produces dysprosium, terbium, yttrium and gadolinium. Electrolysis uses far more energy, while calcium reduction runs in batches.
| Route | How it works | Elements made this way | Energy | Strengths and limits |
|---|---|---|---|---|
| Molten-salt electrolysis in a fluoride bath | Oxide dissolves in a bath of rare earth fluoride and lithium fluoride, typically 80% to 90% rare earth fluoride, at over 850 °C. A tungsten or molybdenum cathode collects the metal and a graphite anode carries the current. | Neodymium, praseodymium and ferrodysprosium; also lanthanum, cerium and mischmetal in chloride baths. | About 12 to 30 GJ per tonne of neodymium | Runs continuously and is easier to control. Uses much energy, graphite and costly electrolyte; the electrolyte can be nearly half of a cell line's initial capital cost (DOE). |
| Metallothermic reduction with calcium | Calcium metal strips the fluorine from a rare earth fluoride, leaving metal and a calcium fluoride slag. Samarium, europium, thulium and ytterbium are reduced from oxide with lanthanum or lithium because of their stable +2 state. | Dysprosium, terbium, yttrium and gadolinium from fluorides; samarium and europium by reduction and distillation. | About 0.5 to 2.5 GJ per tonne of neodymium | Needs less energy but runs in batches and corrodes the furnace lining. The price of calcium can outweigh the energy saving (OSTI). |
| Sodium reduction of chlorides | Sodium metal reduces anhydrous rare earth chloride, a method similar to the Hunter process for titanium. | Listed by the Department of Energy as a commercial route. | Not stated | Anhydrous rare earth chlorides absorb water from air, sodium is imported and the sodium chloride by-product must be separated (DOE). |
Energy figures are from the OSTI review and are ranges across published studies. Which US plant uses which route is mostly not published; MP Materials' filing says electrowinning, and Phoenix Tailings describes a molten-salt electrolysis process.
Why is turning rare earth oxide into metal so hard?
Rare earth oxides are among the most stable metal oxides, so they resist reduction. The usual routes need hydrogen fluoride, run at high temperature and use a lot of energy, and the cells need tungsten, molybdenum and graphite. The Department of Energy concluded that buying oxide and selling metal on the open market is unlikely to pay for a US plant.
- Chemistry Very stable oxides Few reducing agents can break rare earth oxides, and direct reduction is very energy intensive (OSTI).
- Hazard Hydrogen fluoride Making the fluoride feed needs wet or anhydrous hydrogen fluoride, which is extremely toxic. Non-fluoride routes exist but are described as highly inefficient (OSTI).
- Energy 12 to 30 GJ per tonne Electrolysis uses about 12 to 30 GJ per tonne of neodymium against 0.5 to 2.5 GJ for calcium reduction, but calcium costs more (OSTI).
- Materials Tungsten, molybdenum, graphite Electrolysis cells use all three, and the Department of Energy lists all three as critical materials (OSTI).
- Economics A thin margin on metal alone In 2019 Chinese NdPr metal sold for only about $4/kg more than the 1.18 kg of oxide needed to make it. The Department of Energy concluded a US maker may succeed if it also makes oxide and magnets, or has local suppliers and buyers.
A DOE-funded Argonne analysis put a cell line for 1,000 t/yr of NdPr at about $8.6M before the building, with the electrolyte alone costing about $50,000 per cell, at 2015 to 2018 prices.
Which US companies make rare earth metal or alloy?
MP Materials, Phoenix Tailings and REalloys make rare earth metal or alloy in the US, and USA Rare Earth casts alloy at Stillwater. Vulcan Elements and Aclara plan metal capacity, and Energy Fuels makes alloy in South Korea. Most publish stated capacity rather than output.
| Plant | What it makes | Stated capacity | Status |
|---|---|---|---|
| IndependenceFort Worth, Texas | NdPr metal since Jan 2025, alloy and magnets in one integrated plant. | Not stated separately from its magnet capacity of about 3,000 t/yr (company). | Plant operating |
| Exeter metal refineryExeter, New Hampshire | Rare earth metals from several feed types; reportedly NdPr metal and a dysprosium-iron alloy. | 500 t/yr of capacity, 200 t/yr built (company-reported). A larger Freedom Facility is planned for 2028. | Plant operating |
| Euclid metallization facilityEuclid, Ohio | Rare earth metals and alloys. | Not published; operating status is company-reported. | Plant operating |
| StillwaterOklahoma | Strip casting and metal for its own magnets. | Part of a 600 t/yr magnet run rate expected by Q4 2026. | Plant operating |
| Blacksburg campusSouth Carolina | Magnets, strip casting, metal and alloy. | 5,000 t/yr of metal and alloy planned; commissioning in 2028. | Plant building |
| Vulcan ElementsNorth Carolina | Plans to add rare earth metal making to its magnet plants. | Not stated. | Plant planned |
| Aclara ResourcesLouisiana | Metals and alloys planned within the scope of an EXIM letter of interest for up to $750M (non-binding). | Not stated. | Plant planned |
| Korean Metals PlantOchang, South Korea | NdFeB alloy and NdPr metal; dysprosium and terbium metal in development. | 1,300 t/yr of alloy now; 3,600 t/yr targeted by the end of 2026. | Outside the US; acquired Aug 28, 2026 |
Capacities are what each company states. See the metal and alloy makers list for every company at this step.
What is the difference between rare earth metal, alloy and magnet powder?
Metal is the reduced element or pair, such as NdPr metal. An alloy mixes it with iron, boron and sometimes dysprosium; a sintered NdFeB magnet is about 30% rare earth, 69% iron and 1% boron by weight. The alloy is ground to a fine powder, which the magnet plant presses and sinters.
| Product | What it is | Where it is made |
|---|---|---|
| NdPr metal (didymium) | Neodymium and praseodymium reduced from NdPr oxide, in the ratio a magnet needs. | Metal plants such as Independence, Exeter and Euclid. |
| Ferrodysprosium (DyFe) | Dysprosium alloyed with iron, added to raise a magnet's resistance to heat. | Electrolysis with an iron cathode, or calcium reduction. |
| NdFeB alloy | NdPr metal melted with iron and boron, with dysprosium or terbium for hot-running grades, and strip cast. | Usually at the magnet plant, as at Independence and Stillwater. |
| Magnet powder | Alloy broken up by hydrogen and jet milled to particles under 10 microns. It can ignite in air. | Next to the magnet press, because it is hard to ship. |
Composition and powder handling are from the Department of Energy supply chain assessment.
What could make rare earth metal making easier in the US?
Researchers are trying to avoid hydrogen fluoride and cut energy by reducing oxide with magnesium, reducing a sodium-neodymium fluoride with calcium, using chloride baths or using ionic liquids. OSTI describes all of them as research stage. Near term, integrating metal making with oxide and magnet production is the route the Department of Energy found most likely to pay.
- Research Routes without hydrogen fluoride Magnesium reduction of neodymium oxide to a neodymium-magnesium alloy, and calcium reduction of NaNdF4, avoid the toxic acid (OSTI, citing 2025 papers).
- Research Chloride electrolysis Papers cited by OSTI describe chloride-based electrolysis as more energy efficient, but chlorides absorb water and give lower current efficiency than fluoride baths.
- Research Ionic liquids They could allow room-temperature electrolysis but face thick liquids, moisture sensitivity and short stability (OSTI).
- Practice Integration A metal maker with its own oxide and magnet customers, such as MP Materials or USA Rare Earth, avoids the open-market squeeze that the DOE analysis found.
Which US companies work on metals and alloys?
Each company page carries its plant, stated capacity and sources.
- MP MaterialsNdPr metal and alloy at Independence
- Phoenix TailingsA 500 t/yr metal refinery in New Hampshire
- REalloysMetallization in Euclid, Ohio
- USA Rare EarthStrip casting at Stillwater and a metal plant planned
- Energy FuelsThe Korean Metals Plant, with US metal plans
- Vulcan ElementsMagnets, with metal making planned
- Metal and alloy makersEvery company at this step
- US producers of NdPrWho supplies the main magnet oxide and metal
- Rare earth mines in the USWhere the feed starts
- Rare earth companies in the USThe full list by step
Questions about rare earth metals and alloys
What is NdPr metal?
It is neodymium and praseodymium reduced from NdPr oxide in the ratio a magnet needs, also called didymium. Magnet makers melt it with iron and boron to make the NdFeB alloy from which they press and sinter magnets.
Why doesn't the US make more rare earth metal?
The oxides resist reduction, the usual routes need hydrogen fluoride and much energy, and a metal maker that buys oxide and sells metal faces a thin margin. The Department of Energy found no US metal refining in 2022; plants are now starting up.
Since when has MP Materials made metal?
MP Materials began making NdPr metal at Independence in Fort Worth, Texas in Jan 2025, and its first NdFeB magnets on commercial equipment in Dec 2025. Independence is a fully integrated metal, alloy and magnet plant, according to its 10-K.
Does Phoenix Tailings make magnets?
No. Phoenix Tailings is a metal maker. Its Exeter, New Hampshire plant has 200 t/yr built and 500 t/yr of capacity (company-reported), and it plans a larger Freedom Facility with initial operations in 2028.
Is rare earth metal much more valuable than oxide?
Not by much. In 2019 Chinese NdPr metal averaged about $4/kg above the cost of the 1.18 kg of NdPr oxide needed to make 1 kg, according to the Department of Energy. OSTI cites a trade-press estimate of $10 to $20/kg for the oxide-to-metal step.
What is the difference between metallization and separation?
Separation splits a mixed concentrate into single oxides by chemistry in solution. Metallization reduces a separated oxide to metal, either in a molten salt with an electric current or with calcium at high temperature.
Sources and verification
Each profile lists its sources, a confidence grade and a verification date. Order of authority: official records (SEC filings, agency documents), company documents and technical reports, research papers, then independent press. Syndicated copies and reference works are labeled and are never the only source for a number. Company-reported figures are labeled as such, and non-binding deals are labeled "letter of intent" or "conditional".
- OSTI review, Minerals Engineering 249 (Kashyap et al., 2026) Research paper
- Department of Energy: Rare Earth Permanent Magnets, Supply Chain Deep Dive Assessment (Feb 2022) Official record
- MP Materials 10-K for 2025 (SEC) Official record
- Energy Fuels 10-K for 2025 (SEC) Official record
- Fortune: Phoenix Tailings rare earth refinery in New Hampshire (Aug 2026) Independent press
- REalloys: Rare Earth Product Offtake Agreement with Critical Metals Corp, dated as of May 18, 2026 (SEC Form 8-K, Exhibit 10.1) Official record
- USA Rare Earth Q2 2026 results (SEC) Official record
- Aclara: EXIM letter of interest for up to $750M (Sept 2026) Syndicated copy
Tags show what kind of source each link is. How sources are ranked
Guides
Which other guides are there?
Ten guides explain each step from mine to magnet, why the US is behind and how to read the technical reports behind each project in this directory.
- The chain Mine to magnet supply chain The five steps from ore to magnet, with every profiled US company at its step.
- The chain How rare earths are mined Open pits, underground mines, coal and mineral sands, and how ore becomes a concentrate.
- The chain How rare earths are separated Solvent extraction, RapidSX and chromatography, and the US plants that use each.
- The chain How rare earth magnets are made Strip casting, pressing and sintering, and the US magnet plants with their stated capacity.
- The chain Rare earth recycling in the US Hydrogen processing, mechanical recovery and chemistry, and why volumes are still small.
- Why the US is behind Why the US cannot process rare earths Capacity against demand, and five obstacles with the evidence for each.
- Reading the reports Types of US rare earth deposits Carbonatite, granite, clay, coal and sands, with every US project mapped to a type.
- Reading the reports How to read a project A stage ladder from exploration to production, with what each study proves and what it does not.
- Reading the reports How to read resource estimates TREO, grade, JORC, NI 43-101 and S-K 1300, with a calculator and a worked example.
- Hub All rare earth guides The five steps from mine to magnet and a reading order for the ten guides.