Carbon mineralization

CO₂ reacts with calcium- or magnesium-rich materials such as slags or concrete to form stable carbonates.

Technical reference · Updated 2026-10-10 · No current-news claim

CaO + CO₂ → CaCO₃ (simplified net reaction)

Where the carbon goes

Carbonate minerals are stable over geological timescales if not recalcined or acid-leached; durability is the strongest of any CCU route.

Conceptual process flow · left to right

01Feedstock qualification
02Preparation
03Carbonation
04Product testing
05Use

From chemistry to process

Feedstocks: Reactive alkaline material, CO₂
Products: Carbonates, Construction materials where qualified
Catalysts: No universal catalyst; mineral reactivity and conditioning control the process
Conditions: Pressure, moisture and particle size depend on feedstock and product route.

Performance & demonstrated scale

Route-specific; curing, aggregate production and waste treatment cannot share one readiness rating.

0.785 t CO₂/t CaO theoretical
Simplified net reaction. Complete carbonation of reactive CaO; real materials contain less reactive phase.

Pathway TRL: not assigned. Project-specific evidence is required.

Economics

Consider feedstock treatment, CO₂ delivery, product value and local transport rather than carbon uptake alone.

Climate considerations

Carbonate retention may be durable, but net removal additionally requires atmospheric carbon and a complete lifecycle balance. Calcining virgin limestone can offset carbonation uptake.

CCU Reality Check · pathway assessment

What remains to be demonstrated?

This initial assessment separates process knowledge from the evidence needed for a commercial conclusion. Missing information is left unresolved.

Dimension	Assessment and evidence gap
CO₂ feedstock availability	No site-specific supplier, volume, purity guarantee or delivery contract has been verified.
Capture and delivered cost	Not quantified. Capture, conditioning, compression and transport need separate boundaries.
Energy and hydrogen demand	Theoretical stoichiometric or thermodynamic values are shown above. Actual process energy and feed losses remain scenario assumptions.
Catalyst and reactor performance	No universal catalyst; mineral reactivity and conditioning control the process. No plant lifetime or sustained performance is verified here.
Product separation	The process flow identifies separation stages where relevant; a quantified separation duty and cost remain unavailable.
CAPEX and OPEX	No plant-specific capital estimate or complete operating-cost dataset is attached.
Minimum selling price	Not calculated. Capital recovery, utilization, financing and a complete operating boundary are required.
Fossil benchmark competitiveness	No verified regional benchmark comparison. Calculator benchmark values, where shown, are illustrative.
Climate performance	Carbonate retention may be durable, but net removal additionally requires atmospheric carbon and a complete lifecycle balance. Calcining virgin limestone can offset carbonation uptake.
Scale-up bottlenecks	Reactive feedstock supply; Grinding and transport energy; Contaminants and leaching; Construction product qualification.
Customer and offtake readiness	No qualified-customer or executed-offtake evidence is attached to this pathway profile.
Policy dependence	Not assessed for a specific project or jurisdiction. Do not assume subsidies or certification eligibility.

Source references

iea.org

Original diagrams and explanatory text. References support process context; no numerical commercial performance has been extrapolated.