Nanokarb vs Coal Dust

What Coal Dust Is Really Costing Your Foundry

Coal dust combusts when molten metal enters the mould. The foundry industry has long believed this combustion produces a protective layer between the metal and the sand — both the conventional explanations for that belief (the "lustrous carbon" hypothesis and the "gas cushion" hypothesis) struggle to hold up under first-principles scrutiny. What the combustion actually does is start a destructive chain reaction inside the sand matrix: temperatures spike in the backing sand, water evaporates prematurely, bentonite loses bond strength, and clay becomes less cohesive. The volatile matter in coal dust (25-40% at 400°C) is the primary driver — it combusts early, creating excessive heat that breaks down the sand system with every thermal cycle.

This is why foundries find themselves constantly adding more bentonite, more water, and more coal dust — chasing a moving target created by their own additives. The system becomes increasingly difficult to control. Rejection rates climb. Finishing costs rise. And every kilogram of coal dust burned releases 3.6 kg of CO2 that now carries a real financial penalty under CBAM. The longer you wait to address this, the more it compounds.

Side-by-side diagram: coal dust combustion chain reaction vs Nanokarb ceramic-nanoparticle protective interface at the mould-metal boundary

See the Difference

Casting with sand sticking defects using coal dust and mould coating

With coal dust + mould coating

Clean casting with Nanokarb and no mould coating needed

With Nanokarb — no coating needed

Casting before shot blasting with coal dust — 6 minutes required

With coal dust coating — 6 min shot blasting

Casting after shot blasting with Nanokarb — only 5 minutes needed

With Nanokarb — 5 min shot blasting, no coating

Side-by-Side Comparison

Parameter Nanokarb Coal Dust / LCA
Mechanism Ceramic-nanoparticle protective interface (no combustion) Combustion-driven (sand chain reaction)
Volatile Matter @ 400°C 0% 25-40%
Volatile Matter @ 925°C < 10% 25-40%
LOI 85% 85-95%
CO2 Emissions Minimum 50% reduction Baseline (3.6 kg CO2 per kg burned)
Replacement Ratio 1 kg Nanokarb = 2 kg coal dust —
Effect on Bentonite Preserves bentonite performance Degrades bentonite through heat
Effect on Backing Sand Minimal temperature rise Significant temperature rise
Surface Finish Superior — immediate improvement Standard
CBAM / EU Compliance Supports compliance Increases carbon footprint
Dosage 0.075% per batch 0.2–0.5% per batch
Equipment Changes Required None —
Safety Classification Non-hazardous, non-explosive Explosive dust hazard

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The Hidden Cost of Staying with Coal Dust

Infographic showing the stacking hidden costs of continuing to use coal dust in foundries

What Foundries Experience

50%

Reduction in Coal Dust Consumption

Min 50%

Reduction in CO2 Emissions

Min 10%

Reduction in Bentonite Consumption

Predicted

Timeline — We Forecast Your Results Before the Trial

We use proprietary predictive tools to forecast your exact results before the trial begins. You'll know what to expect — and you hold us accountable.

Switching Is Simpler Than You Think

3-step process for switching from coal dust to Nanokarb in your foundry

Is Nanokarb Right for Your Foundry?

Nanokarb works with all ferrous castings — grey iron, ductile iron, and steel — on all moulding lines, whether HPML, jolt-squeeze, or manual.

Integration requires zero equipment changes. If you have a spare hopper, use it. If not, Nanokarb loads alongside your existing coal dust. Your sand formula doesn't change. Your bentonite doesn't change. Your process doesn't change.

Ready to Compare in Your Own Foundry?

Request a zero-risk Nanokarb trial. We'll predict the results before you start using proprietary forecasting tools — and you hold us accountable. No lock-in. No penalties. Just results you can measure.

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