Steelmakers source coal very differently from power plants. A blast furnace depends on a carefully designed blend of coking coals, plus PCI coal, and small changes in quality can affect coke strength and furnace output. Good sourcing starts with a precise specification and continues with qualified suppliers, solid contracts and independent inspection.
1. Define what each coal must do
Most steel plants buy several coals for different roles:
| Role | Coal type | Key properties |
|---|---|---|
| Coke making, main blend | Hard coking coal | Coke strength (CSR), low ash, low sulphur and phosphorus |
| Coke making, blend extenders | Semi-hard and semi-soft coking coal | Lower cost; adjust volatile matter and fluidity |
| Furnace injection | PCI coal | Low ash, suitable volatile matter and grindability |
| Sinter plant | Anthracite fines or coke breeze | Fixed carbon, size |
| Power and steam | Thermal coal | Calorific value, ash, sulphur |
See anthracite vs bituminous for steelmaking.
2. Write a complete specification
For coking coal, include ash, volatile matter, sulphur, phosphorus, moisture, CSR and CRI of the coke, fluidity, swelling index, and size. For each, set a typical value and a rejection limit. See why steel plants need high-grade coal.
3. Qualify mines, not just sellers
Coking coal quality is tied to specific mines and seams. Before adding a new coal to the blend:
- Get the mine name and seam, and historical analysis data
- Test a trial cargo or a pilot coke oven sample
- Check consistency across several shipments
4. Diversify origins
Relying on one mine or country leaves a plant exposed to floods, strikes, rail problems or policy changes. Most large steelmakers combine coal from Australia, North America and other origins. See top coal exporting countries.
5. Use the right contract structure
- Term contracts for the core blend, with an agreed price index or formula
- Spot purchases to fill gaps or test new coals
- Quality clauses with price adjustments and rejection rights
- Force majeure terms that are clear on both sides
6. Inspect at loading and discharge
Independent sampling and analysis at loading, and testing on arrival, protect against quality disputes. Make sure the contract states which result is final.
7. Manage stocks and logistics
Keep enough stock to ride out shipping delays, and store coals separately so the blend stays accurate. Weather at loading ports, for example heavy rain in Queensland, can delay cargoes for weeks.
8. Track total cost, not just price
A cheaper coal that raises the coke rate or slag volume can cost more overall. Evaluate coals by their effect on hot metal cost, not only their price per tonne.
Thermal coal for steelworks power and boilers
Agromer holds mandates for Indonesian thermal coal, used in power plants, boilers and kilns rather than as coking coal. If your steelworks runs its own power plant or boilers, send us your specification, monthly quantity, contract length and discharge port. See our Indonesian coal supply page.
Frequently asked questions
What coal is used in steel manufacturing?
Mainly coking coal for coke, plus PCI coal injected into the blast furnace. Thermal coal is used for on-site power and steam.
Why do steel plants blend coals?
Blending different coking coals lets the plant reach the coke quality it needs at the lowest overall cost.
What is hard coking coal?
The highest grade of coking coal, which makes strong coke and commands the highest price.
How do steelmakers check coal quality?
By independent sampling and analysis at loading and on arrival, plus coke oven testing for new coals.
Why diversify coal suppliers?
To reduce the risk of supply disruptions from weather, logistics or policy at a single mine or country.
Is the cheapest coal the best value?
Not always. Coal that increases the coke rate or slag volume can raise the total cost of producing iron.