Foundry Coal Dust
Foundry coal dust, also called sea coal, is finely milled bituminous coal added to green sand moulding mixes. As molten metal fills the mould, the coal releases volatiles that form a thin carbon film between metal and sand, giving cleaner castings with a better surface finish and less burn-on. We supply consistent, milled coal dust to iron and steel foundries across South Africa.
Typical foundry coal dust specification
| Property | Typical range |
|---|---|
| Raw material | Milled bituminous coal |
| Volatile matter | about 30 – 38% |
| Ash | low; stated per batch |
| Moisture | dried; stated per batch |
| Fineness | milled to suit green sand systems |
| Packaging | 25 kg bags and bulk bags |
Exact values are confirmed on the certificate of analysis for each batch.
Why foundries use coal dust
- Improves casting surface finish on grey and ductile iron
- Reduces metal penetration and burn-on
- Helps castings strip cleanly from the mould
- Reduces veining and expansion defects
Typical addition rate
Coal dust is usually added at about 3 – 8% of the green sand mix, depending on the casting section, metal type and the sand system. Foundries normally adjust the rate against loss on ignition (LOI) and volatile content measured in the system sand.
Related foundry and refractory minerals
- Silica flour for mould and core coatings
- Quartz sand for moulding and core sand
Frequently asked questions
Is foundry coal dust the same as anthracite?
No. Foundry coal dust is a high-volatile bituminous coal. Anthracite has very low volatile matter and does not form the carbon film green sand needs.
Can you match our current coal dust specification?
Send your current specification or a sample analysis and we will match volatile matter, ash and fineness.
Do you deliver to foundries outside Gauteng?
Yes, nationwide, including KwaZulu-Natal, the Eastern Cape and the Western Cape.