Wielding a shiny chrome scoop, Michael Rosenthal leans over and digs into the powder in a half-filled 55-gallon drum. He holds up the scoop and takes a pinch in his fingers and smooshes it to show me the texture. It’s like talc, but it’s an odd, beautiful shade of pale green-gray. On shelves all around us are huge white bags of the stuff, each weighing a metric ton.
The fact that this particular powder exists at all is basically a miracle. That’s the inescapable conclusion for me at this point after a sort of impromptu, peripatetic mini-seminar conducted by Rosenthal here in
Mountain Pass, Calif., near the Nevada border. Rosenthal is cofounder and chief operating officer of MP Materials, the only company in North America that is mining rare earth ore and—this is the important part—extracting from it large quantities of industrially useful rare earth compounds.
The powder he’s showing me is a mixture of pure
rare earth oxides, mostly neodymium with some praseodymium. It’s the key ingredient in countless critical processes and products in semiconductor manufacturing, electro-optical systems, chemical catalysis, and, most notably, powerful permanent magnets. These are the magnets that go into nearly all motors for electric vehicles and into climate-control systems, appliances, and tools, into the generators used in wind turbines, and into the hundreds of millions of headphones and loudspeakers sold each year.
For the past couple of hours, as the temperature climbed toward 43 °C (110 °F), I’ve been traipsing with Rosenthal around
MP’s open-pit mine and sprawling processing facilities in the northeastern Mojave Desert. Earlier, as we stood on the edge of the vast mine pit, Rosenthal pointed out in the walls of light grayish “country rock” far below us the seams of brownish and reddish rock, which contain the rare earth ores. “There’s been rare earth mining here since 1952,” he said. “We think we’ve got at least another 30 years to go.”
That’s a comforting thought to government officials and tech executives in Europe, North America, Japan, and Korea, which have launched sprawling programs to produce the vital elements in the United States, Australia, and Canada. The efforts are aimed at ensuring a supply of critical rare earths in the event that China—which produces
roughly 90 percent of processed, industry-ready rare earths—decides to restrict their export. Now, after more than a decade of effort, and after billions of dollars spent by private companies as well as the U.S. and other governments, 2025 will be a year when some results of all this money and activity should become conspicuous.
“The track record of success in this industry is abysmal.”
—Michael Rosenthal, cofounder, MP Materials
MP Materials, for example, expects to increase production this year of its neodymium praseodymium product, while also completing a facility to produce finished, high-quality permanent magnets near Fort Worth, Texas. Meanwhile, MP’s only large competitor outside of China,
Lynas Rare Earths of Perth, Australia, expects to begin work on a mammoth rare earth–processing facility being built in Seadrift, Texas with US $258 million from the U.S. Department of Defense (DOD).
But every bit as potentially transformative as these big, publicized projects is one hardly known at all, even within the small community of rare earth investors, developers, and researchers. This year, researchers at Oak Ridge National Laboratory will operate and analyze a pilot line based on a new chemical-extraction method, invented by chemist
Santa Jansone-Popova. It appears capable of reducing the solvents, water, and energy needed to extract rare earths by as much as 60 percent in comparison with the standard extraction process. Such a technological advance could eventually prove indispensable for U.S., Australian, and other companies struggling to compete against the Chinese rare earth juggernaut, which operates scores of processing facilities, and is less constrained by environmental regulations.
The Rare Earths Business Defies Categorization
There’s pretty much nothing straightforward about the rare earths industry. It’s a technology-based commercial endeavor upon which many other global, critical, cutting-edge industries depend. It also happens to be at the hot nexus of geopolitics and defense. And it’s an industry with an historically checkered environmental record that is now pivotal to some of the largest and fastest-growing industries aimed at mitigating climate change.
The unease over China’s dominance of rare earth production spiked last December, when China announced it would
begin banning the export to the United States of certain critical materials. Notably, the ban does not include rare earths, but the prohibition evoked a 2010 incident in which China temporarily cut all rare earth sales to Japan after a fishing dispute. Three years later, a report from the U.S. Congressional Research Service created a furor by pointing out that each F-35 Lightning II fighter jet contained 414 kilograms (about 920 pounds) of rare earth materials.
Pretty soon, the money began gushing. It came from U.S. agencies, notably
the DOD, as well as others in Japan and Korea and from private investors. Scores of companies and ventures sprang up—at last count, more than 146 large rare earth projects were underway, of which at least 96 were in North America, Australia, Europe, and South America.
In the United States, most efforts focus on self sufficiency. But the road from here to there is going to be pretty rough. “Making rare earths is really, really hard,” says Rosenthal. “It’s very expensive, you need a lot of equipment, and the track record of success in this industry is abysmal.”
So, not surprisingly, almost all of those 146 big rare earth projects are mining ventures, not processing ones, and they’ll do very little to diversify the rare earth supply. “It’s important that we have a more diverse supply chain, outside of China, and a bigger one,” agrees Rosenthal. “But the industry is poorly served by the amount of hype and unjustifiable press regarding resources (exploratory mine sites) that are not well understood. What we really need more of is processing capabilities, from all parts of the supply chain.” A new rare earth mine, Rosenthal points out, does nothing to increase the geographical diversity of supply if its output must go to China to be processed into rare earth oxides.
Neodymium-bearing rare earth compounds, such as this neodymium praseodymium oxide powder produced by MP Materials at its Mountain Pass site, are of immense industrial, military, and commercial importance.MP Materials
Today, such arrangements are common. China’s dominance of rare earth processing is such that even MP Materials Corp., the parent company that controls the Mountain Pass mining and processing operations, sends some of its ore to China for processing. And a Chinese company, Shenghe Resources Holding Co., owns approximately 7.7 percent of the stock of MP Materials.
“China has built at least 50 rare earth separation plants in the last 10 years,” Rosenthal estimates. For comparison, outside of China, there are only three separation facilities capable of producing rare earth oxides at industrial scale. One is Mountain Pass; another is the Silmet factory in Sillamäe, Estonia, which is owned by Toronto-based Neo Performance Materials; and the third is the huge
Lynas advanced materials plant, near Kuantan in Malaysia. (Another Lynas facility, in Kalgoorlie, Australia, produces a mixture of rare earth carbonates that can be turned into industrially useful oxides at customer sites.)
Redistributing Refining
Refining rare earth ore into rare earth oxides begins with a process called
beneficiation in the industry. Here, the rocks are first broken down into chunks of gravel that are then mixed with water and crushed into a slurry. Then, in the relatively environmentally friendly process used at Mountain Pass, called froth flotation, a kind of chemical reagent called a surfactant is added to the slurry. This mixture is introduced into a series of vessels, or cells, in which the surfactants cause the rare earth–bearing grains to bind selectively to bubbles floating to the top of the cells. As the bubbles float upwards, they carry the rare earth–bearing grains with them, separating them from the waste grains. After multiple stages, what’s left after drying is a fine powder called rare earth concentrate. The goal is for this concentrate to be at least 60 percent rare earth oxides by weight.
The next step is called leaching. At Mountain Pass, the concentrate is roasted and then leached with hydrochloric acid to put the high-value rare earth elements into solution. Most of the cerium, a low-value rare earth, is removed in this stage.
Bags of neodymium praseodymium oxide powder, each containing one metric tonne of the compound, await shipping from a warehouse at the Mountain Pass site in California.Michael Tessler/MP Materials
The next stage is the most complicated and important. Here, the specific rare earth elements being sought, for example neodymium and praseodymium, are separated from the other rare earths. The standard technique is called
solvent extraction, and it is not much different from the process invented 70 years ago by researchers at Argonne National Laboratory and Oak Ridge National Laboratory.
The method is called liquid-liquid because it uses two immiscible solvents, one water- and the other oil-based. The rare earths are dissolved in one of the solvents, which is mixed vigorously with the other one. To separate out specific rare earths, the process uses an organic extractant and exploits subtle differences in the affinity of that extractant for different rare earth elements under particular process conditions.
Here’s how it works. There’s a water-based, acidic solution containing the rare earths, which is called the aqueous phase. It’s mixed with an oil-based, or organic, phase, consisting of that organic extractant and a diluent. Technicians adjust the process conditions, such as temperature and pressure, to allow the extractant to bind preferentially to the specific rare earth ions to be recovered, say neodymium. When the aqueous phase and the organic phase are mixed vigorously, those neodymium ions bind to the extractant, which pulls them into the organic phase. Because this oil-based phase is not miscible with the aqueous one, the neodymium ions are separated from the others. In practice, the vigorous combining occurs in vessels called mixers, and then the combined liquids are pushed into an adjacent container called a settler, where the two phases slowly separate, with the target rare earths accumulating in the organic phase and the less-desired rare earths being scrubbed back into the aqueous phase.
This mixing and settling happens over and over again. Each time the concentration of the desired rare earths is increased incrementally. After many iterations, the target rare earths are then typically transferred back to the aqueous phase. Then they’re recovered by means of a precipitation technique.
If it all sounds pretty straightforward, it’s not. At Mountain Pass, Rosenthal takes me into the building, larger than a football field, where the extraction takes place. I’ve toured plenty of imposing industrial and technological sites, but I’ve never seen anything quite like this. After my eyes adjust to the dim light, I see columns of huge, paired vessels, towering over me, off into the distance. They’re each about 20 cubic meters (roughly 5,000 gallons), and there are at least a hundred of them (the exact number is a trade secret, I am told). These are the mixers and settlers.
How Oak Ridge Reinvented Rare Earth Extraction
Properly tuned, the liquid-liquid solvent-extraction process can be extremely effective, producing rare earth oxides with purity greater than 99.9 percent. But it has some substantial drawbacks. In the process, the organic phase is a phosphate-based compound, such as tributyl phosphate, and the aqueous phase is a strong acid, such as hydrochloric, nitric, or sulfuric. These solvents and reagents are used in enormous quantities, which can be recycled but must all be disposed of eventually.
Lots of research now is aimed at
identifying better extractants—for example, ones that enable less acidic processes or that chemically bind more selectively with the desired rare earths. A measure of the effectiveness of an extractant is separation factor, which indicates how much of the target rare earth element is pulled from solution relative to adjacent rare earths as they go through one round of mixer-settlers. For the conventional system today, the separation factors of adjacent rare earths vary between 1.1 and about 6. For comparison, separation factors for other chemical-industrial processes can exceed 100.
“If you can double or triple the separation factor, then you could halve or reduce the number of mixer-settlers by up to two-thirds,” says Tom Lograsso, director of a U.S. government-led consortium called the
Critical Materials Innovation Hub, which is sponsoring research on the problem. “If there was a panacea to reduce the costs, the capital costs, the land usage, the water usage, and improve the environmental soundness of the processing, it would be to come up with chemicals that are environmentally safe, and that would also do a better job of separating the rare earths from each other.”
Research chemist Santa Jansone-Popova, at Oak Ridge National Laboratory, invented the DGA-6 chemical that could revolutionize rare earth extraction.Carlos Jones/ORNL/U.S. Department of Energy
At Oak Ridge, the project led by Jansone-Popova, with funding from the Critical Materials Innovation hub, is doing exactly that. Jansone-Popova notes that with the conventional process, the solutions become more acidic as they proceed through successive stages of mixer-settlers.
“In order to recover those rare earth elements in that oil-aqueous separation system,” she explains, “you have to use more concentrated aqueous solution—more acidic solution,” she notes. That, in turn, she adds, requires the use of alkali to lower the acidity of that solution, so that the aqueous stream can be recycled. “That means adding more chemicals to the system, which is not ideal, and which, at the end, results in producing more waste, generating environmental concerns,” she says.
Her solution? Use an extractant that does not operate based on adjustments in acidity. “It operates by a different mechanism, adjustments in ionic strength,” says Jansone-Popova. “That means we can start with a more concentrated acid solution, and then we can recycle that acid solution without adding any chemicals. And when we want to recover those rare earth elements, we’re using a very dilute acidic solution that, too, can be recycled after the precipitation of the rare earths. We can basically recover those rare earth elements with water. There are no additional chemicals added to the system, and all the acid that we’re using in the process can be recycled. That’s the beauty.”
And it’s not even
all the beauty. The new extractants are also far more selective, improving the separation factor by two to three times in comparison with the existing processes.
A new high-efficiency process for extracting specific rare earth elements was pioneered at Oak Ridge National Laboratory. The process depends on a chemical, diglycolamide-6 (DGA-6) [in beaker above] which is now being manufactured by Marshallton Research Labs.Carlos Jones/ORNL/U.S. Department of Energy
The new extractant is from a chemical family called diglycolamides, or DGAs. Jansone-Popova refers to the one her team is currently developing as DGA-6. It’s used in the oil phase, and another new extractant, also developed by her team, is used in the aqueous phase. “Our goal is to do the flow sheet demonstrations and to convince industry that this is a better process,” she declares.
She already has one convert in industry. Mac Foster is co-owner of
Marshallton Research Laboratories, which provides chemicals for extraction processes in the nuclear and rare earth industries. He’s been collaborating with Jansone-Popova, and he likes what he sees. “Compared to the state-of-the-art [traditional-process extractants], this new class of DGAs is much cleaner in its operation because these extractants are neutral,” he says. “They’re not acids. So they don’t require big swings involving neutralization of large amounts of acid. They’re more efficient.”
Marshallton, which has a license to manufacture DGA-6, has been making relatively small quantities of it for evaluation and testing at Oak Ridge. The company has also been providing advice on commercialization to Jansone-Popova’s team. “We have improved the manufacturing process for DGA-6,” Foster adds. “By that, I mean what we’re doing is not in the literature. And it leads to a lower cost to make the extractant. It’s better suited for scaling up.”
Back at Mountain Pass, I ask Rosenthal about the Oak Ridge work. He likes what he’s heard so far. “If the Oak Ridge extractant is more selective, we wouldn’t need as many tanks,” he notes.
Over the longer term, Western rare earth producers are going to need something extraordinary to bolster their efforts to compete with their Chinese counterparts—who are also pursuing diglycolamides as
extractants for rare earth processing. If it isn’t the Oak Ridge process it’ll have to be something very much like it. And the sooner the better.