CAMBRIDGE — Rock Zero, a startup co-founded by MIT professor Yet-Ming Chiang, has developed a new method to extract lithium from spodumene using ammonium fluoride, avoiding hazardous chemicals and high-temperature processing. The technique, detailed in the journal Science, operates in stirred plastic tanks at temperatures up to 95°C (200°F) and yields lithium carbonate, alumina, and cementitious silica as products.

The process eliminates the need for hydrofluoric acid, which is typically used in hard-rock lithium extraction and poses environmental and safety risks. Instead, it uses ammonium fluoride—a weak acid that can be reused in a closed loop—and targets spodumene, the most abundant lithium ore globally. Researchers estimate that at full scale, lithium could be extracted for less than $6,000 per metric ton if ammonium fluoride is efficiently recycled, a cost competitive with brine extraction and lower than conventional hard-rock methods.

“At scale, we believe this will be the lowest-cost way of sourcing lithium in the world,” Chiang said. He described the approach as “nose-to-tail” mining, utilizing all components of the ore. Camden Hunt, CEO and co-founder of Rock Zero, said avoiding high-temperature roasting could reduce energy costs and carbon emissions.

Rock Zero has designed a pilot plant and aims to complete construction by the end of 2026, with operations starting in 2027. The company is in talks with potential partners in the mining industry. Laboratory-scale tanks in Cambridge, Massachusetts, can process three kilograms of spodumene concentrate per batch.

Simon Jowitt, chair of exploration geology at the University of Nevada, Reno, expressed skepticism about the economic projections. “People are waiting to see what happens with the lithium price. It’s a crowded market, and there’s some big players out there.” He noted that the lithium market remains relatively small despite rising battery demand, contributing to price volatility, and added that new technologies must also contend with alternatives like sodium-ion batteries.