Blast furnace burden
Charged direct: even size and crushing strength keep the burden permeable.
Iron ore pellets
Fired iron ore pellets: fines balled with a binder and indurated at around 1,300 °C into hard, porous spheres. At 64% Fe minimum and a basicity of 0.10 these are acid pellets, the grade used for direct reduction and for blast furnace charging.
- Grade / purity
- Fe 64% min
- Form
- Pellets
Applications
Direct reduced iron
Reduced to sponge iron in coal-fired rotary kilns and gas shaft furnaces.
Electric arc furnace
The sponge iron made from them is a clean metallic charge beside scrap.
Specification
| Above 18 mm | 5% max |
|---|---|
| Below 5 mm | 5% max |
| Correct size | 90% min |
| Cold crushing strength (CCS) | 200+ kg/pellet (avg) |
| Tumbler index | 94.5 min |
| Abrasion index | 4.5 max |
| Porosity | 23.0% min |
| Fe | 64% min |
|---|---|
| Silica | 4.5% max |
| Al2O3 | 3.0% max |
| Basicity | 0.10 |
| Sulphur | 0.005% max |
| Phosphorus | 0.040% max |
Basicity is the CaO to silica ratio. At 0.10 these are acid pellets rather than fluxed.