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11 Technology-Based Carbon Pathway · TTS Annex F
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Industrial Waste Mineralisation
TTS v1.0 - Annex F

Industrial Waste Mineralisation captures CO₂ from a flue gas stream or ambient air and reacts it, above ground, with alkaline industrial residues - steel slag, cement kiln dust, fly ash, and mine tailings - that would otherwise sit unused in stockpiles. Accelerated carbonation permanently locks the CO₂ into stable calcium and magnesium carbonate phases within the waste material itself, turning an industrial liability into a durable carbon sink while avoiding the emissions of virgin feedstock disposal.

Technological TTS v1.0 Annex F ⏳ Class III · Mineral ● Active
Submit Waste Mineralisation Project View TTS v1.0 Annex F →
>1,000 yr
Storage timescale (Class III)
Days–weeks
Time to full carbonation
$60–$200
Current cost per tonne
4
Approved methodologies
IWM-M01 through IWM-M04
Teravent Methodology Codes · TTS Annex F
View TTS Annex F →
Overview

How this pathway works

Industrial Waste Mineralisation puts alkaline residue streams from steelmaking, cement production, coal combustion, and mining to productive climate use. These materials - steel slag, cement kiln dust (CKD), fly ash, and ultramafic mine tailings - contain calcium and magnesium oxides and silicates that react readily with CO₂ under accelerated carbonation conditions: elevated pressure, controlled humidity, or fine grinding to increase reactive surface area. The captured CO₂ converts to solid calcium or magnesium carbonate within the waste material itself, typically within days to a few weeks - the fastest confirmed mineralisation timeline of any Teravent pathway.

Under the Teravent Technology-Based Carbon Standard (TTS v1.0) Annex F, Industrial Waste Mineralisation projects earn Teravent Technology Credits of the Reduction type (TTC-D) for verified net tonnes of CO₂ permanently mineralised in ex-situ waste processing, net of full lifecycle project emissions. Unlike In-situ Mineralisation (Annex E), which injects CO₂ into a subsurface formation, this pathway processes waste material above ground - in dedicated carbonation reactors, curing yards, or ex-situ treatment cells - before the carbonated product is stockpiled, used as construction aggregate, or returned to a mine site.

Four methodology variants are approved under Annex F, differentiated by waste feedstock type. Each specifies its own reactivity assay requirements, carbonation process conditions, and counterfactual fate analysis for the waste material.

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Class III - Mineral permanence. All credits issued under TTS Annex F carry Class III permanence, reflecting the >1,000-year stability of the calcium and magnesium carbonate phases formed. Buffer pool contributions of 2–8% of gross verified credits apply, reflecting the very low reversal risk of ex-situ mineralised material once carbonation is confirmed. Because the primary CO₂ source for this pathway is typically industrial flue gas rather than atmospheric air, credits are classified as TTC-D (Reduction) rather than TTC-R (Removal).
Governing Standard

TTS v1.0 - Annex F

This pathway is governed exclusively by the Teravent Technology-Based Carbon Standard (TTS v1.0). No external registry, standard, or methodology is referenced or incorporated. All requirements - additionality, quantification, durability, safeguards, and credit issuance - are defined within TTS v1.0 and Annex F specifically.

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TTS-001-v1.0 · Annex F · Active
Teravent Technology-Based Carbon Standard
TCR› TTS v1.0› Annex F - Industrial Waste Mineralisation› IWM-M01 through IWM-M04
M02 Three-test additionality with TRL-based screening applied ahead of common practice test
M03 Quantification and MRV - Net TTC formula, carbonation reactor CO₂ uptake metering at ±2% accuracy
M04 Class III Mineral permanence · Buffer pool 2–8% · SIRR assessed at each verification
M05 Environmental and social safeguards - DNSH on air quality, water use, and leachate management
M06 Ten-stage registration process; 17-element PDD including counterfactual waste fate analysis
M07 TTC serial: TCR–TTS–D–IWM–[Country]–[ProjectID]–[Vintage]–[Unit]
View Full TTS v1.0 → Jump to Annex F MRV Requirements
Teravent Technology Credit - Serial Number Format (TTS Annex F · Reduction)
TCR – TTS – D – IWM – CN – 00054 – 2025 – 000001
Registry TCR
Standard TTS v1.0
Pathway Code IWM
Credit Type TTC-D - Reduction Credit
Durability Class III · Mineral
Methodologies Accepted

Four approved methodology variants

TTS v1.0 Annex F approves four discrete methodology types for the Industrial Waste Mineralisation pathway. Each code represents a distinct waste feedstock with its own reactivity profile, carbonation process, and counterfactual fate considerations. A facility processing multiple waste streams must declare and meter each feedstock under its own methodology code.

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Counterfactual fate is central: All four methodologies require a documented counterfactual fate analysis for the waste feedstock. Where the material would otherwise have been landfilled, stockpiled indefinitely, or used in a lower-value application with no CO₂ uptake, the mineralisation project is additional. Where the material already undergoes passive weathering or is already a common carbonation feedstock in the region, a baseline carbonation rate must be deducted.
IWM-M01
Steel Slag Carbonation
Basic oxygen furnace and electric arc furnace slag reacted with CO₂ in accelerated carbonation reactors or curing yards
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Steel slag - a co-product of basic oxygen furnace (BOF) and electric arc furnace (EAF) steelmaking - is rich in free lime (CaO) and calcium silicates that react rapidly with CO₂ under humid, elevated-temperature curing conditions. Processing occurs either in dedicated pressurised reactors for maximum uptake rate, or in open curing yards where crushed slag is periodically turned and sprayed with water while exposed to a concentrated CO₂ stream. The carbonated slag product is frequently sold as a construction aggregate, generating an additional revenue stream alongside carbon credit issuance.

Permanence
Class III · Mineral
Buffer Pool
2–6% (by SIRR)
CO₂ Uptake Metering
Reactor inlet/outlet gas analysis, ±2%
Reactivity Assay
Free lime content (%) per batch, XRD confirmation
Counterfactual Fate
Landfill / uncarbonated stockpile baseline required
Time to Carbonation
Days (reactor) to weeks (curing yard)
Key Monitoring Indicators
  • CO₂ gas uptake at reactor inlet and outlet via calibrated gas analysis, ±2% accuracy
  • Slag free lime content and particle size distribution per processing batch
  • Carbonate mineral content of processed product confirmed by thermogravimetric analysis (TGA) or X-ray diffraction (XRD)
  • Counterfactual fate documentation - landfill, stockpile, or lower-value use avoided
  • Product end-use tracking where carbonated slag is sold as aggregate, to prevent double counting of embodied carbon claims
IWM-M02
Cement Kiln Dust (CKD) Carbonation
Alkaline bypass dust from cement kilns treated with CO₂ in slurry-phase or fluidised bed reactors
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Cement kiln dust, a fine alkaline particulate captured from cement kiln exhaust systems, contains free lime and alkali chlorides that readily absorb CO₂ when suspended in a slurry or processed through a fluidised bed carbonation unit. This methodology is frequently co-located with the cement plant itself, allowing direct use of the plant's own flue gas as the CO₂ source, closing the loop between emission and mineralisation on a single industrial site.

Permanence
Class III · Mineral
Buffer Pool
2–7% (by SIRR)
CO₂ Source
Typically co-located cement kiln flue gas
CO₂ Uptake Metering
Slurry/fluidised bed inlet-outlet gas analysis, ±2%
Counterfactual Fate
Landfill disposal baseline required
Time to Carbonation
Hours to days (slurry/fluidised bed process)
Key Monitoring Indicators
  • CO₂ gas uptake at reactor inlet and outlet via calibrated gas analysis
  • CKD alkalinity and free lime content per processing batch
  • Carbonate content of treated product confirmed by TGA or XRD
  • Where co-located with a cement kiln, verification that the flue gas CO₂ source is not double-counted against any separate CCUS credit claim at the same facility
  • Leachate quality monitoring for treated CKD stockpiles under DNSH water provisions
IWM-M03
Fly Ash Carbonation
Coal combustion fly ash reacted with CO₂ to form stable carbonates, frequently for use in carbon-cured concrete products
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Fly ash from coal-fired power generation contains calcium oxide and other alkaline compounds capable of reacting with CO₂, particularly Class C fly ash from sub-bituminous or lignite coal sources. This methodology covers both dedicated ex-situ carbonation of stockpiled ash and carbonation occurring during the curing of fly-ash-blended concrete products, where injected CO₂ both mineralises and improves the compressive strength of the finished material.

Permanence
Class III · Mineral
Buffer Pool
2–8% (by SIRR)
Feedstock Grade
Class C (high-calcium) fly ash preferred
CO₂ Uptake Metering
Curing chamber gas analysis, ±2%
Counterfactual Fate
Ash pond disposal or uncarbonated concrete baseline
Time to Carbonation
Hours (curing chamber process)
Key Monitoring Indicators
  • CO₂ gas uptake within curing chamber via calibrated gas analysis, ±2% accuracy
  • Fly ash calcium content and reactivity assay per feedstock source
  • Carbonate content confirmed by TGA at representative sampling frequency
  • Where product is a concrete blend, overlap check against CO₂ Concrete Curing (Annex J) to prevent double-registration of the same mineralised tonnes
  • Counterfactual fate documentation for the ash - ash pond disposal, landfill, or lower-value use avoided
IWM-M04
Ex-Situ Mine Tailings Carbonation
Ultramafic mine tailings excavated, crushed, and processed through dedicated carbonation reactors to accelerate mineral uptake
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Where in-situ injection into a standing tailings impoundment is impractical (Annex E, INM-M02), tailings material can instead be excavated, mechanically ground to increase reactive surface area, and processed through a dedicated ex-situ carbonation reactor or spread in engineered curing beds with controlled CO₂ exposure. Grinding substantially accelerates reaction kinetics relative to passive in-situ weathering, at the cost of additional handling energy that must be deducted from the net credit.

Permanence
Class III · Mineral
Buffer Pool
2–6% (by SIRR)
Feedstock Verification
Mineralogical assay for reactive olivine/serpentine content
Handling Energy
Excavation, grinding, and transport deducted from net credit
CO₂ Uptake Metering
Reactor or curing bed gas analysis, ±2%
Time to Carbonation
Days to weeks (ground material, accelerated conditions)
Key Monitoring Indicators
  • CO₂ gas uptake at reactor or curing bed inlet/outlet via calibrated gas analysis
  • Mineralogical assay confirming reactive silicate content of ground tailings feedstock
  • Excavation, grinding, and transport energy consumption logged for lifecycle deduction
  • Carbonate mineral content of processed material confirmed by TGA or XRD
  • Final disposition tracking for carbonated material - return to tailings site, construction use, or other end use
Project Boundary & GHG Accounting

Which emission sources must be counted

TTS v1.0 Module 3 requires a full lifecycle GHG emissions inventory within the project boundary, deducted from gross mineralised CO₂ to arrive at the Net TTC figure. A source may be excluded only where its inclusion would reduce the net carbon benefit (conservative assumption) and this is documented in the PDD.

Required
Mineralised CO₂ (Gross)
Primary benefit quantity. CO₂ gas uptake continuously or batch-metered at the carbonation reactor or curing yard, confirmed as converted to carbonate mineral phase via TGA or XRD analysis.
Required
Waste Handling & Processing Energy
Excavation, grinding, conveying, and reactor operating energy for all four methodologies, applying the applicable grid emissions factor or verified renewable/nuclear PPA documentation under TLP v1.0.
Required where material
CO₂ Source Capture & Transport
Where CO₂ is captured from an on-site or nearby flue gas stream and transported to the carbonation process, associated capture and transport emissions must be assessed unless already fully accounted under a separate registered capture pathway.
Required where material
Counterfactual Waste Fate
Where the waste material would otherwise have undergone passive carbonation or an alternative low-carbon disposal route, the baseline counterfactual emissions or carbonation rate must be deducted from the gross credit.
Excluded
Original Industrial Process Emissions
Emissions from the steelmaking, cement production, or coal combustion process that originally generated the waste feedstock are excluded - these are addressed, where applicable, under the facility's own separate emissions accounting, not under this pathway's boundary.
Excluded - Prevents Double Counting
Overlapping Product-Embodied Carbon Claims
Where carbonated product is separately marketed with an embodied-carbon or building-material carbon claim, that portion of mineralised CO₂ is excluded from Teravent credit issuance to prevent double counting across value chains.
MRV Confidence

Measurement, reporting
& verification

Teravent's Science Advisory Board assesses each pathway against four MRV dimensions. Industrial Waste Mineralisation benefits from a controlled, above-ground process environment, giving it very high measurement confidence, though additionality clarity is somewhat lower given variability in regional waste-handling baselines.

CO₂ Uptake QuantificationVery High
Mineralisation ConfirmationVery High
Permanence ConfidenceVery High
Additionality ClarityMedium–High
🔬 Measurement Requirements - TTS Module 3

CO₂ uptake is quantified through calibrated gas analysis at the carbonation reactor or curing chamber inlet and outlet, accurate to ±2%. Mineralisation is directly confirmed - unlike subsurface pathways, which rely on modelling - through thermogravimetric analysis (TGA) or X-ray diffraction (XRD) of representative product samples, quantifying the exact carbonate mineral content formed. Feedstock reactivity assays (free lime content, mineralogical composition) are required at registration and updated whenever the waste source changes materially. All laboratory analyses must be conducted by an accredited facility, and all gas metering instrumentation calibrated by an accredited VVB.

Additionality

Demonstrating additionality

TTS v1.0 Module 2 requires all projects to pass a three-test additionality framework, with a Technology Readiness Level (TRL) screen applied ahead of the common practice test. The common practice test carries particular weight for this pathway, since passive weathering of some waste feedstocks already occurs to a limited degree without any project intervention.

1
TRL-Based Common Practice Screen
Projects deploying accelerated carbonation technology at TRL 7 or below automatically satisfy the common practice test. Facilities using mature commercial carbonation equipment (typically IWM-M01 steel slag processing) must instead complete a full common practice survey documenting the proportion of comparable regional waste streams already undergoing active carbonation absent carbon finance.
2
Regulatory Surplus Test
The carbonation activity must not be mandated by any legally binding waste management, landfill diversion, or industrial byproduct utilisation regulation. Where a jurisdiction mandates slag or fly ash reuse for non-climate reasons (e.g. construction material standards), projects must demonstrate the specific carbonation process - as opposed to simple reuse - exceeds the regulatory requirement.
3
Financial Additionality Test
Carbon revenue must be necessary for project viability. Developers must submit a discounted cash flow analysis, net of any government grants, tax incentives, or aggregate product sale revenue, demonstrating that carbonation processing costs exceed available revenue absent carbon credit income. Product co-revenue (e.g. sale of carbonated aggregate) must be included transparently in the analysis, not omitted.
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Government incentive disclosure: Where a project receives direct government grants, capital cost subsidies, or per-tonne tax credits for the same mineralised CO₂, this must be disclosed to the TSA at registration under Module 8. Double-claiming the same carbon benefit under both a government incentive programme and Teravent credits is prohibited.
Leakage Assessment

Leakage types & deductions

TTS v1.0 Module 3 defines three leakage types applicable across all engineered pathways. Industrial Waste Mineralisation projects are primarily subject to energy-source leakage, waste-diversion leakage, and - where applicable - a carbonated-product market leakage assessment.

Energy-Source Leakage
Grid Electricity Displacement
Where excavation, grinding, and reactor equipment draws electricity from a constrained grid, its consumption may increase marginal fossil generation elsewhere. Facilities without a dedicated renewable or nuclear power purchase agreement must apply the regional marginal emissions factor.
Deduction: applicable regional grid factor, TLP v1.0
Waste-Diversion Leakage
Alternative Reuse Displacement
Where the waste feedstock would otherwise have been used in an alternative application (e.g. uncarbonated slag as road base, fly ash as an uncarbonated cement additive) that application's demand may be met by another material source, requiring a market displacement assessment.
Default: 3–5%, assessed at PDD stage
CO₂ Source Double-Counting Risk
Overlap with Registered Capture Pathways
Where the CO₂ source is a co-located capture facility already registered under a separate Teravent pathway (e.g. CCUS, Annex C), chain-of-custody documentation must confirm the same captured CO₂ is not credited twice - once at the capture stage and again at the mineralisation stage.
Zero-tolerance exclusion · verified each period
Permanence & Storage Integrity Risk

Buffer pool & reversal risk

All Annex F credits carry Class III Mineral permanence (>1,000-year storage horizon). Because mineralisation is confirmed directly through laboratory analysis of the finished product - rather than modelled from subsurface monitoring - reversal risk for this pathway is very low once carbonation is verified. Buffer rates are set by the project's Storage Integrity Risk Rating (SIRR).

Methodology SIRR Rating Buffer Pool Rate Primary Reversal Risks
IWM-M01 Steel Slag Very Low 2–6% Incomplete curing prior to product sale; product misclassification at end use
IWM-M02 Cement Kiln Dust Very Low 2–7% Leachate exposure altering carbonate stability; storage site water infiltration
IWM-M03 Fly Ash Very Low 2–8% Product overlap risk with concrete curing claims; incomplete curing
IWM-M04 Ex-Situ Mine Tailings Low 2–6% Post-processing storage site erosion; incomplete grinding reducing reaction extent
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Reversal notification: Project proponents must notify the TSA within 72 hours of discovering a reversal event - for example, laboratory re-analysis revealing lower-than-reported carbonate content, or confirmed leaching of carbonate minerals at a storage site. Buffer pool credits are cancelled proportionally to the verified carbon loss. Operators additionally carry 30-year post-closure monitoring obligations for stockpiled carbonated material storage sites.
Eligibility Requirements

Key registration criteria

Projects must meet all of the following minimum requirements to qualify for registration under TTS Annex F. Additional methodology-specific requirements are detailed in the Annex F methodology tables for each IWM-M code.

✓
Calibrated CO₂ gas uptake metering installed at the carbonation reactor or curing chamber inlet/outlet, accurate to ±2%
✓
Feedstock reactivity assay submitted at registration (free lime content, mineralogical composition) and updated whenever the waste source changes materially
✓
Ten-stage registration process completed, from technology eligibility assessment through validation to ongoing verification, per TTS Module 6
✓
Seventeen-element Project Design Document submitted, including a documented counterfactual waste fate analysis
✓
Three-test additionality demonstrated with TRL-based screening applied first; TRL documentation updated at each verification
✓
Post-carbonation product testing by TGA or XRD confirming carbonate mineral content, at a minimum sampling frequency specified per methodology
✓
Storage Integrity Risk Rating (SIRR) assessed by an accredited VVB at validation; buffer pool contribution of 2–8% applied to gross verified credits
✓
Chain-of-custody documentation confirming no double counting where CO₂ source is a separately registered capture facility
✓
Do No Significant Harm review covering air quality (dust from grinding/handling), water quality (leachate), and worker health and safety
✓
Government production incentive or capital grant disclosure submitted at registration and updated at each verification period
Co-Benefits & SDGs

Sustainable Development
Goal alignment

All Teravent registered Industrial Waste Mineralisation projects must complete an SDG impact assessment at registration and at each verification period. Three SDGs are systematically tracked for this pathway. Projects may apply for co-benefit quality labels where independently verified indicators are met.

SDG 12 · Responsible Consumption & Production SDG 13 · Climate Action SDG 9 · Industry, Innovation & Infrastructure
Circular Feedstock+
All four IWM methodologies convert industrial waste streams into productive climate use rather than requiring virgin resource extraction, making this the pathway most consistently eligible for the Circular Feedstock co-benefit label.
Zero Fossil Input+
Facilities powered entirely by verified renewable or nuclear electricity for excavation, grinding, and reactor operation are eligible for the Zero Fossil Input co-benefit label.
Community Benefit+
Facilities located at industrial sites or legacy mining regions that demonstrate local employment creation, land remediation, or reduced landfill burden for surrounding communities are eligible for the Community Benefit+ label.
Water Positive+
Projects that reuse process water within a closed-loop curing system and demonstrate net-positive local water balance are eligible for the Water Positive label where hydrological monitoring data is provided.

Deployment scope: Global - feedstock is generated wherever steel, cement, and coal power facilities operate, or wherever legacy mine tailings deposits exist, making this one of the most geographically flexible engineered pathways in the Teravent system.

Continue Exploring

Related pathways

🪨
TTS Annex E · Technological
In-situ Mineralisation
→
🛢️
TTS Annex G · Technological
Geologic CO₂ Storage
→
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TTS Annex A · Technological
Direct Air Capture
→
🏭 Industrial Waste Mineralisation · TTS Annex F

Ready to register your
waste mineralisation project?

Submit a Project Concept Note under TTS v1.0 Annex F to begin your registration. Select the IWM-M code matching your waste feedstock, install calibrated CO₂ uptake metering, and appoint an accredited VVB to validate your PDD and counterfactual waste fate analysis.

Submit under TTS Annex F Back to All Pathways