In recent years, the reduction of CO₂ emissions and the stable supply of raw materials are two major issues for the steel industry. Low reducing agent operation in the blast furnace is required to reduce CO₂ emissions in ironmaking. As a mean of realizing low reducing agent operation with using low-grade raw materials, ferro coke characterized by high coke reactivity is considered to be useful. Theoretical and experimental studies were carried out to verify the effect of the ferro coke usage on reaction behavior in blast furnace.
Investigation of CO₂ reactivity at the simulated blast furnace condition revealed that the initial temperature of CO₂ reaction of ferro coke is lower than the temperature of conventional coke. At the temperature of over 1100°C, the deterioration of ferro coke strength after reaction was depressed because the reaction occurred preferentially at the surface of the ferro coke.
The coke and ferro coke strength after reaction was estimated based on the experimental results with the two-dimensional mathematical model of the blast furnace. The average coke strength of ferro coke and conventional coke with charging of ferro coke (100 kg/t) was little less than the coke strength without ferro coke charging. It is predicted that the carbon saving with charging of ferro coke (100 kg/t) is about 6% in comparison to without ferro coke charging.