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| Century Aluminum |
US-origin alumina supply could gain a new domestic source after Century Aluminum agreed to take material from Brimstone’s planned industrial-scale refinery. The agreement supports efforts to reduce US dependence on imported alumina as domestic primary aluminium capacity expands.
US-origin alumina from Brimstone will be produced from calcium-bearing silicate rocks rather than conventional bauxite. The company plans a 350,000 t/yr smelter-grade alumina refinery, with operations targeted to begin in 2034.
US-origin alumina is becoming strategically important because the US relied on foreign sources for 71% of its alumina requirements in 2025. Imports reached 1.3mn t, while domestic refining capacity remains concentrated in a single operating facility.
Neither the offtake volume nor financial terms of the memorandum of understanding were disclosed. However, the agreement gives Brimstone an industrial customer pathway while Century strengthens its potential long-term raw material security.
Domestic Alumina Becomes Critical as US Smelting Expands
Century Aluminum is increasing primary aluminium production as US trade policy raises the cost of imported metal. The company restarted more than 50,000 t/yr of idled capacity at its Mt Holly smelter in South Carolina.
Century is also participating with Emirates Global Aluminium in plans for a new 750,000 t/yr primary aluminium smelter in Oklahoma. If those projects advance, domestic alumina demand will rise alongside US smelting capacity.
The supply problem is clear. Atlantic Alumina’s 1.2mn t/yr Gramercy refinery in Louisiana is currently the only domestic source of smelter-grade alumina.
Even that facility depends on imported bauxite from Jamaica. This means US primary aluminium production remains exposed to foreign raw material supply even when smelting occurs domestically.
Brimstone’s proposed process could change that equation. Its hydrometallurgical technology extracts alumina from calcium-bearing silicate rocks, potentially creating a US feedstock route that does not depend on imported bauxite.
The company is also evaluating other products from the same process, including cement, iron, titanium and magnesium. That multi-product model could improve resource efficiency and project economics if successfully commercialised.
Brimstone Must Prove Scale Before 2034 Supply Begins
Brimstone is currently building a commercial-scale demonstration plant in Reno, Nevada. Operations are expected to begin in 2028, with initial alumina output intended for customer qualification.
That qualification step will be critical. Aluminium smelters require consistent chemistry, purity and physical characteristics before they can use new alumina sources at scale.
The demonstration plant therefore serves as the bridge between process development and industrial acceptance. Brimstone must prove that its non-bauxite route can produce smelter-grade material reliably and economically.
The industrial-scale refinery remains further away. Brimstone has not selected a final site, while the planned 2034 start date means Century will continue relying on existing alumina sources for several years.
Financing is another issue. Brimstone has raised more than $80mn from equity investors but has not disclosed updated capital requirements for its demonstration or commercial refinery.
The company is also challenging the US Energy Department’s decision to revoke a $189mn award previously intended to support the demonstration plant.
The strategic case remains strong. If Brimstone can commercialise its process, the US could gain a new domestic alumina route just as primary aluminium capacity begins expanding again.
The Metalnomist Commentary
The US cannot build a secure aluminium industry by adding smelters while leaving alumina dependent on imports. Brimstone’s real significance is whether it can turn domestic silicate rock into qualified smelter-grade alumina at commercial scale.
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