DRI use in the EAF
CDRI, HDRI, and HBI all have applications in the EAF and offer the following benefits:
- Very low residual element content
- Predictable, uniform & certified chemical analysis
- Predictable mass and heat balances
- Carbon content can be tailored to EAF requirements
- Easier to handle than scrap
- Can be continuously fed to the furnace
- Can be hot-charged in integrated plants
- Better slag foaming
- Control of nitrogen in steel
- Melt consistency
EAF
Electric Arc Furnace
HBI use in the Blast Furnace (BF)
Due to its physical properties, HBI is the preferred form of DRI for blast furnace use. It can increase hot metal production and lower coke consumption and can be used as up to 30 percent of the BF charge with no significant equipment or process changes.
The addition of HBI increases hot metal production as more metallics are added in the BF burden: 8 percent more production when burden metallization is increased 10 percent or 24 percent more hot metal when metallization is increased to 30 percent.
This is highly desirable when:
- Hot metal availability is insufficient to meet demand
- Hot metal requirements are not matched to blast furnace output
- One blast furnace is offline for maintenance
DRI use in the Basic Oxygen Furnace (BOF)
HBI is the form of DRI best suited for use in the BOF because of its bulk density and physical strength. It is an alternative to coolant scrap because:
- Residuals levels are lower
- Bulk density is higher
- Mass and heat balances are more accurate
- Steel chemistry is easier to control
Advantages of using HBI include:
- The cooling effect of HBI is approximately 10% greater than the cooling effect of scrap steel.
- There is no increase in slopping relative to using all scrap as the cold charge.
- There is no sculling on the lance.
- HBI can be used for low sulfur steels.
- HBI has lower levels of tramp elements than steel scrap.
HBI may be charged to the BOF from either:
- An overhead bin, or
- The charging box as up to 1/3 of the cold charge.