US-Origin Alumina Deal Targets Supply Security for Century Aluminum

Century Aluminum

US-origin alumina could become a new domestic feedstock source for Century Aluminum under an agreement with Brimstone, which plans to develop a 350,000 t/yr smelter-grade alumina refinery using calcium-bearing silicate rocks.

US-origin alumina is strategically important because the US relied on imports for 71% of its alumina requirements in 2025. Imports reached 1.3mn t, exposing domestic primary aluminum production to overseas raw material and logistics risk.

US-origin alumina from Brimstone would use a different feedstock route from conventional bauxite refining. The company plans to extract alumina through a hydrometallurgical process while also targeting products including cement, iron, titanium and magnesium.

The industrial-scale refinery is targeted to begin operations in 2034, meaning the agreement is primarily a long-term supply security initiative rather than an immediate solution to US alumina dependence.

Alternative Feedstock Could Diversify US Alumina Production

Brimstone plans to produce alumina from calcium-bearing silicate rocks rather than imported bauxite. This could give the US another domestic pathway for supplying smelter-grade material to primary aluminum producers.

The planned refinery will have capacity of 350,000 t/yr, although Brimstone has not yet selected a final site. Offtake volumes under the Century agreement were also not disclosed.

The US currently has only one domestic alumina source, Atlantic Alumina's 1.2mn t/yr Gramercy refinery in Louisiana. That plant depends on Jamaican bauxite and has not operated at full utilisation.

A successful Brimstone project would therefore diversify both feedstock and processing routes.

Century has additional reason to secure future domestic alumina. The company is restarting more than 50,000 t/yr of idled primary aluminum capacity at Mt Holly and is participating in plans for a 750,000 t/yr Oklahoma smelter with Emirates Global Aluminium.

More primary smelting capacity will require more reliable alumina supply. Without new domestic refining, higher US metal production could deepen dependence on imported feedstock.

Demonstration Plant Must Prove Commercial Alumina Quality

Brimstone first needs to prove that its alternative process can consistently produce alumina suitable for commercial smelters.

The company is building a demonstration plant in Reno, Nevada, with operations targeted for 2028. Material from the facility will be used for customer qualification before the larger refinery is developed.

Qualification will be critical because aluminum smelters require tightly controlled alumina chemistry, particle characteristics and handling performance.

The long timeline also creates execution risk. Brimstone must complete demonstration work, secure financing, select an industrial site and scale the process before commercial production begins in 2034.

The company has raised more than $80mn from equity investors but is also challenging the cancellation of a previously awarded $189mn federal funding package.

If the technology succeeds, the strategic benefit could extend beyond alumina. Co-production of titanium, magnesium, iron and cement-related materials could improve project economics while creating additional domestic mineral supply.

The Metalnomist Commentary

The US cannot fully secure primary aluminum production while remaining heavily dependent on imported alumina. Brimstone's approach is strategically attractive because it targets both domestic feedstock and alternative refining technology, but commercial qualification and scale-up remain the decisive hurdles.