harnessing the power of co-production
Our breakthrough process delivers multiple market-ready industrial materials—starting with cement.
our products
THE BRIMSTONE PROCESS MAKES PORTLAND CEMENT, SUPPLEMENTARY CEMENTITIOUS MATERIALS AND SMELTER GRADE ALUMINA.
Brimstone produces industry-standard alumina in addition to our first co-products, cement and SCM. Alumina is the key ingredient in aluminum, a critical material and the second-most consumed metal in the world.
we start with a common, carbon-free rock
conventionally made CEMENT uses LIMESTONE, ACCOUNTing FOR 60% of TOTAL EMISSIONS.
The Brimstone process replaces limestone with carbon-free, calcium-bearing silicate rocks. These highly abundant rocks are found on the surface of every continent, enabling us to make our products efficiently, economically, and sustainably—virtually anywhere.
our process
The Brimstone process produces two essential products used in concrete: portland cement and supplementary cementitious MATERIALs (SCM).
Cement and SCM are typically made through separate processes and sourced from different locations. Our rock contains all the necessary elements to produce both industry-standard cement and SCM from one process and in one location. Our process is deeply decarbonized across a range of energy scenarios.
we start with a carbon-free feedstock
TRADITIONAL CEMENT RELIES ON LIMESTONE AS ITS CORE FEEDSTOCK, WHICH ACCOUNTS FOR 60% OF CEMENT'S TOTAL EMISSIONS.
The Brimstone process replaces limestone with highly abundant and carbon-free calcium silicate rocks, dramatically reducing our cement's carbon footprint from the start.
PORTLAND CEMENT
ASTM C150
Brimstone cement meets or exceeds ASTM C150 standards for portland cement, the most widely used cement in the world.
TRICALCIUM SILICATE CONTENT
>60%
28 DAY STRENGTH
>6000 PSI
SUPPLEMENTARY CEMENTITIOUS MATERIALS
ASTM C618 CLASS N
Brimstone SCM meets the physical and chemical requirements of ASTM C618 Class N.
r3 heat release
>200 J/g
28 DAY STRENGTH ACTIVITY INDEX
>100%
SMELTER GRADE ALUMINA
Industry specifications
Under development
ALUMINA CONTENT
>99%
Portland cement has been the foundation of modern construction for over 200 years, comprising virtually the entire U.S. cement market. As the key binder in concrete, it’s critical to building infrastructure—from skyscrapers and bridges to roads and homes. Its durability, versatility, and affordability have made it the trusted material for engineers worldwide.
Over time, other cements have been developed and marketed as alternatives to portland cement. But these alternative cements produce concrete with different properties, such as setting times, expansive behavior, and strength development. They are used primarily for niche applications and have not gained broad traction as a portland cement replacement.
The problem? Portland cement production comes at a massive climate cost, accounting for 7.5% of global CO₂ emissions—three times that of aviation.
Brimstone is changing that. Our team developed an efficient, economical and sustainable process to deliver conventional portland cement that meets existing industry standards (ASTM C150). We’re not altering the material—just how it’s made—to seamlessly integrate into the production process, scale efficiently, and build a better future.
what is portland cement?
SCM is added to concrete to partially replace portland cement, improving its strength and durability while reducing its carbon footprint.
Common SCMs include ground granulated blast furnace slag and fly ash—materials typically sourced from coal-fired steel production or electricity generation.
With the switch from blast furnaces to electric arc furnaces and the decline of coal-fired power plants, conventionally sourced SCM is becoming increasingly scarce.
However, Brimstone has developed a solution. Brimstone produces an SCM that meets existing standards and comes from a co-production process with ordinary portland cement—enabling these materials to reliably and seamlessly integrate into the construction supply chain.
One rock. One process. Multiple essential industrial ingredients.
what is SCM?
Alumina is the feedstock used to produce aluminum—a critical material and the world’s second-most consumed metal. It plays a vital role across industries, including defense, aerospace, transportation, construction, technology, consumer goods, and clean energy.
The U.S. depends heavily on imports throughout the aluminum supply chain—producing less than 17% of the primary aluminum it consumes, only about 9% of the alumina required to make that aluminum, and 0% of the mined ore (bauxite) needed to produce that alumina. The U.S. has only one operating alumina refinery today.
Unlike conventional alumina production, which depends on bauxite (an ore typically sourced from tropical and subtropical regions overseas), Brimstone’s feedrocks are widely available, reducing the dependence on the limited number of countries with economic bauxite reserves. This unlocks the ability to produce alumina efficiently and sustainably, virtually anywhere.
The Brimstone plant could be the first new domestic source of smelter grade alumina in more than 50 years.
what is alumina?
step 1
geology
Portland cement is made from calcium and silica. Traditionally, this process involves heating limestone, which releases CO₂—about 60% of cement’s emissions come from the heating of limestone. The Brimstone process starts with a different feed rock: calcium-bearing silicate rocks, which contain no embedded CO₂. Brimstone obtains the feed rocks from simple quarry operations.
step 2
mineral processing
A key part of the process is mineral processing, or comminution. During the comminution step, Brimstone crushes the feed rock to the desired particle size.
our process
The Brimstone process produces three essential industrial materials: portland cement, sCM and smelter grade alumina.
Cement, SCM and alumina are typically made through separate processes and sourced from different locations. Our rock contains all the necessary elements to produce all three industry-standard products from one process and in one location. Our process is deeply decarbonized across a range of energy scenarios.
step 3
hydrometallurgy
Next, the Brimstone team mixes the calcium silicate rock with chemicals to extract calcium and aluminum. These elements are separated to extract calcium compounds for cement and aluminum compounds for alumina. The residual silicates are then dried and processed to make SCM.
step 4
pyrometallurgy
Brimstone heats the extracted oxides in a rotary kiln to produce clinker, an intermediate product. The clinker is then milled with gypsum to create ordinary portland cement. Brimstone’s process is compatible with a wide range of energy scenarios, including clean energy.
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PORTLAND CEMENT
ASTM C150
Brimstone cement meets or exceeds ASTM C 150 standards for portland cement, the most widely used cement in the world.
TRICALCIUM SILICATE CONTENT
>60%
28 DAY STRENGTH
>6000 PSI
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SUPPLEMENTARY CEMENTITIOUS MATERIALS (SCM)
ASTM C618 CLASS N
Brimstone SCM meets the physical and chemical requirements of ASTM C618 Class N.
r3 cumulative heat release
>200 J/g of SCM
28 DAY STRENGTH ACTIVITY
>100%
step 1
geology
Portland cement is typically made from calcium and silica. Traditionally, this process involves heating limestone, which releases CO₂—about 60% of cement’s emissions come from heating limestone. The Brimstone process starts with a different feed rock: calcium silicates, which contain no embedded CO₂. Brimstone mines the feed rocks using a simple quarry operation and sends them to the lab.
step 2
mineral processing
A key part of the process is mineral processing, or comminution. During the comminution step, Brimstone crushes the feed rock to the desired particle size.
step 3
hydrometallurgy
Next, the Brimstone team mixes the calcium silicate rock with chemicals to extract calcium and other elements needed for cement production. These elements are separated to increase the calcium content to the level necessary for making portland cement. The remaining solid residue, rich in silica, becomes Brimstone's SCM material.
step 4
pyrometallurgy
A rotary kiln heats the calcium compounds to produce clinker, which is then milled with gypsum to produce portland cement. Brimstone separately processes the extracted aluminum compounds to produce alumina.
