Decrease in the Carbon Consumption of a Commercial Blast Furnace by Using Carbon Composite Iron Ore

Abstract

Increasing coke gasification rate can lowers the temperature of the thermal reserve zone, resulting in a decrease of carbon consumption and a reduction of the reducing agent rate of blast furnaces. To achieve this increase, the enhancement of coke reactivity itself or the close arrangement of iron ore and carbonaceous materials has been investigated in Japan. Against this, RCA, “Reactive Coke Agglomerate,” having a high carbon content, has been developed, and it was found that the agglomerate mixed-in sinter layer had two functions: one having high reducibility itself and the other enhancing the reduction of the surrounding sinter. As a result of the two functions, a significant decrease of the temperature of the thermal reserve zone and an increase of gas utilization by using the agglomerate mixed-in sinter layer in a BIS test was achieved. As for the strength after reaction, disintegration was fairly small in comparison with that of the sinter both in the laboratory scale test and in a basket test using a plant’s vertical probe. Long-term plant trials have been conducted at the Oita Works No.2 Blast Furnace with a maximum use of 54 kg/tHM. It was found that RCA could lower the temperature of the thermal reserve zone and carbon consumption in a commercial blast furnace. Carbon consumption was decreased along the relationship of 0.36 kgC/tHM per 1 kgC/tHM of input carbon from RCA.