Analysis on material and energy balances of ironmaking systems on blast furnace operations with metallic charging, top gas recycling and natural gas injection

The iron and steelmaking industry has been receiving social pressure to reduce energy consumption and environmental load as recent increase in the social awareness on environmental and resource problems. The ironmaking system consumes more than a half of overall energy input to the steelwork and its improvement is expected as a countermeasure for such problems. Numerous attempts through improving the blast furnace operation have been made. This paper analyzes material and energy balances of ironmaking system that consists of hot stove, coke oven, CDQ, sintering and blast furnace. The operation statuses of the blast furnace with natural gas injection, metallic charging and top gas recycling that have been obtained by the kinetic-based numerical simulations are applied to this analysis. The results suggested that the metallic charging to blast furnace decreases both energy input and CO2 emission. The natural gas injection operation decreases the CO2 emission from the iron making system while the decrease in the energy input is small. The top gas recycling operation increases the CO2 emission due to the scrubbed CO2 from the recycled top gas.