How a new extraction process could unlock the world's lithium

Researchers say they have found a new way to extract lithium, a crucial metal used in lithium-ion batteries that power electric vehicles and energy storage systems. This new technique could be more environmentally friendly and less expensive than existing techniques.

The research was published today in Science and a startup called Rock Zero is working to commercialize the process.

“At scale, we think this will be the cheapest way to source lithium in the world,” says Yet-Ming Chiang, one of the study's authors, an MIT professor and serial entrepreneur behind climate technology companies including Form Energy and Addis Energy.

Currently, the most economical way to obtain lithium is to extract it from brine, the salt water that has extracted the metal from rock over millennia. But this technique is geographically limited and currently requires vast areas of land for massive evaporation ponds. The most common tactic is hard rock mining, where large quantities of ore are destroyed, cooked at high temperatures, and processed using dangerous chemicals.

The researchers' new method uses a weak acid to dissolve typically unreactive silicate minerals. This releases not only lithium, but also other useful materials, including alumina and silica.

The origins of this research and the resulting company came from another startup founded by Chiang, Sublime Systems, which makes cement using electrochemistry.

The team was trying to find a source of highly reactive silica to form a stronger cement. One way to make reactive materials, which can easily bind to other materials, is to take a non-reactive material, dissolve it, and then let it become solid in a more reactive form. It is not impossible to dissolve silicates, but the most common method is to use hydrofluoric acid, an extremely dangerous chemical. Other fluorine-containing chemicals are also candidates, but some will produce hydrofluoric acid as a side product during reactions.

Chiang was inspired by a previous home improvement project involving glass, which was made from silica. “I was remodeling a shower in Framingham, Massachusetts, about 25 years ago,” he says. "So when we started this project, I remembered this glass etching cream and thought, 'What's in this?' »

The glass etching cream he remembers, which can be found on the shelves of any craft or home improvement store, uses ammonium fluoride, a weak acid. And MIT researchers found that under the right conditions, it can effectively dissolve silicate minerals without producing hydrofluoric acid in the process.

This chemistry could be useful for all silicate minerals, and there are many. But spodumene, the mineral often mined for lithium, has become a prime target. (Chiang says a suggestion from Doug Wicks, one of the company's advisors and former head of ARPA-E, pointed the team in the direction of spodumene.)

Today, a key step in processing spodumene ore involves roasting it in an oven at very high temperatures. This causes a phase transformation, essentially swelling the material and making the lithium more accessible.

By avoiding having to reach these temperatures, you could save on energy costs and potentially reduce carbon emissions as well, says Camden Hunt, one of the study's authors and CEO and co-founder of Rock Zero.

Avoiding the oven could also unlock the ability to use certain ores that can't be roasted properly, Hunt adds. Ore that contains too much iron will not phase change properly, but will melt and turn into a glassy material.

The new process relies on simple stirred plastic tanks and takes place at temperatures up to around 95°C (200°F). Ammonium fluoride dissolves silicates, which in previous experiments allowed almost all of the lithium in spodumene ore to be extracted within a few days. Researchers have since reduced that time to less than 12 hours, says Benjamin Mowbray, first author of the study and CTO and co-founder of Rock Zero.

The products (after a few additional cleaning steps) are lithium carbonate, which can be used to make batteries; alumina, which can be used in a foundry to make aluminum; and cementitious silica, which can be added to concrete. And the acid can be reused in the same loop.

Chiang calls this “nose-to-tail” mining, meaning it uses every part of the ore supplied, like eating every part of a slaughtered animal.

Researchers are currently working to evolve and optimize the process. Tanks at the Cambridge, Massachusetts, laboratory can process three kilograms of spodumene concentrate in each batch.

They also estimated the cost of this process once fully scaled. Assuming the ammonium fluoride can be recycled at a high level, they should be able to extract the lithium for less than $6,000 per metric ton. (They also identified a potential industrial source of cheap acid, as an alternative to recycling.)

The total cost is expected to be lower than other processes used today to extract lithium from hard rock ore, and it could be competitive with brine.

The team has designed a pilot plant and is looking for space to build it. Construction is expected to be completed by the end of 2026 and operation of the facility to begin in 2027. Discussions are ongoing with potential mining industry partners.

One of the difficulties for new players in lithium mining is the volatility of the market: prices have seen huge fluctuations in recent years, from a peak in 2022 to a low at the end of 2024 and a slow rise from the beginning of 2026.

Rising prices could benefit new players like Rock Zero, but many projects could come online if prices continue to rise, which could set back the market, says Simon Jowitt, chair of exploration geology at the University of Nevada, Reno. “People are waiting to see what happens to the price of lithium,” he says. “It’s a crowded market and there are big players.”

And even if batteries drive demand for lithium, the market remains relatively small, Jowitt adds: “That means it's going to be volatile. » New lithium extraction technologies like Rock Zero's will have to compete with methods used by existing giants, and it's also possible that technological alternatives, like sodium-ion batteries that don't need lithium, will make navigating the market more difficult, Jowitt says. He also thinks some of the company's economic estimates could be optimistic.

For its part, the Rock Zero team hopes not only to extend this technology to lithium, but also to use it for other minerals in the future. As Mowbray says: “The earth’s crust is made up of silicates.”

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