In a period of high global demand steelworks are focusing on maximum productivity. To obtain high
productivity requires stable furnace operation at high feed rates of reductants and sinter and/or
pellets. These higher feed rates result in increased gas flows leading to the need to maintain or
improve permeability in the lower and upper zones of the blast furnace. At injection rates, greater
than 140 kg/tHM, it has been observed that changes were occurring in the operation of the blast
furnace. Some of these changes are:
- Reduction in coke/ore ratio,
- The size of the raceway,
- Reduction of permeability of the coke surrounding the raceway,
- Changes in temperature distribution in the raceway,
- Mechanical degradation of coke in the raceway, and
- Decrease in deadman temperature.
All these changes are interdependent and are influenced by the properties and amount of the
injected coal, coke quality and blast conditions, as shown by the Figure 1.
|
|
|
Figure 1 Factors that influence blast furnace performance in the lower zone
|
