Brimstone Rock Refinery Decarbonized Portland Cement

Brimstone is a US industrial technology company founded in 2019 by Cody Finke and Hugo Leandri, who met at Caltech, and is based in Oakland, California. It targets the CO2 released when limestone is heated to make cement, which accounts for about 60% of cement emissions, by starting from calcium silicate rocks that contain no embedded carbon.

Its Rock Refinery process quarries and crushes silicate rock, extracts calcium and aluminium through hydrometallurgy, and burns the calcium compounds in a rotary kiln into clinker that is milled with gypsum into ordinary portland cement meeting ASTM C150. The residual silicates become a supplementary cementitious material meeting ASTM C618 Class N, and the aluminium compounds are processed into smelter-grade alumina. Target buyers are cement distributors, ready-mix and precast producers, contractors and aluminium smelters.

• Silicate rock feedstock: uses calcium-bearing silicate rocks with no embedded CO2 instead of limestone.
• Hydrometallurgical extraction: chemically separates calcium for cement and aluminium for alumina.
• On-spec portland cement: clinker milled with gypsum meets ASTM C150 with 28-day strength above 6,000 psi.
• SCM co-product: residual silicates processed into an ASTM C618 Class N supplementary cementitious material.
• Smelter-grade alumina: alumina above 99% purity under development as a domestic alternative to bauxite.
• Multi-product roadmap: future plants are planned to add steel, aluminium, magnesium and titanium.

Vietnamese cement groups can evaluate a joint venture or licensing route to build silicate-rock clinker lines that cut process emissions ahead of carbon market obligations. Ready-mix producers supplying green-certified projects can source on-spec low-carbon OPC and SCM. Aluminium and mining companies can explore co-production of alumina and cement from local silicate deposits.

The cement is chemically ordinary portland cement meeting ASTM C150, with over 60% tricalcium silicate and 28-day strength above 6,000 psi, so it can be used wherever OPC is specified without new codes. Avoiding limestone removes the process emissions behind about 60% of cement CO2. A peer-reviewed study estimates that co-producing cement and SCM cuts total energy by about 30%. Co-products such as alumina add revenue streams to each plant.

Cement producers face pressure to cut process emissions that blending and fuel switching cannot remove, and buyers increasingly want drop-in low-carbon cement that needs no change to building codes. In Southeast Asia, where cement output is large and carbon pricing and green building rating are expanding, technologies that keep standard OPC chemistry while removing limestone emissions are attractive for licensing or joint ventures.

Founded in 2019 by Cody Finke (CEO) and Hugo Leandri; office at 1731 Poplar Street, Oakland, California. Selected by the US DOE Office of Clean Energy Demonstrations for up to USD 189 million toward a first commercial plant with total project investment of up to USD 378 million; site options include Oklahoma and Reno, Nevada. In May 2026 a peer-reviewed paper co-authored by its CEO was published in Communications Sustainability.