Article ID: ISIJINT-2025-269
The blast furncace (BF) with the operartion of top gas recycling had been generally recognized as an innovative ironmaking technology, with some significant advantages including the reduction of fuel ratios and CO₂ emission and the enhancement of BF smelting. In this work, a multi-fluid model and life cycle assement of top gas recycling-blast furnace (TGR-BF) was applied to systematically investigate the smelting behavior and carbon reduction potential with the varying theoretical combustion temperature (TCT). As the TCT increased from 2000°C to 2250°C, the production of TGR-BF increased from 5184.0 t/d to 5693.8 t/d, coke ratio increased from 220.2 kg/tHM to 248.3 kg/tHM, and the CO2 emission increased from 893.75 kg/tHM to 1017.5 kg/tHM. The raceway coke combustion increased from 93.01 kg/tHM to 114.83 kg/tHM, coke consumption for direct reduction reactions rose from 21.39 kg/tHM to 26.86 kg/tHM, and the coke loss in carbon solution loss reactions decreased from 53.45 kg/tHM to 53.13 kg/tHM. And H2 contribution to FeO→Fe decreased from 67.10% to 63.23%, while CO contribution to FeO→Fe increased from 32.90% to 36.77%. Increasing TCT enhanced the smelting efficiency of the TGR-BF. However, the resulting rise in coke rate caused by intensified direct reduction and tuyere combustion, coupled with the increased proportion of CO consumed during indirect reduction, adversely affected the emission reduction benefits of the TGR-BF. Consequently, these factors required comprehensive consideration when selecting the appropriate TCT level.
