Top gas recycling blast furnace developments for 'green' and sustainable ironmaking

The ultralow CO2 steelmaking blast furnace process (ULCOS-BF) aims at minimising the CO2 emissions of the BF by at least 50%. This process is based on the replacement of hot blast by oxygen, the recycling of hot decarbonated top gas into the lower shaft and normal hearth tuyeres, and the capture of CO2 and its storage in a geological trap (full CO2 capture and storage process). The paper highlights the main technologies of this process and the expected benefits for CO2 mitigation. The ULCOS-BF has been demonstrated during three campaigns of 7 weeks each by coupling the LKAB experimental BF in Lulea to a pilot vacuum pressure swing absorption unit for CO2 removal. The concept, preparation and results of the campaigns are described.