CO₂ emission evaluation and cost analysis of oxygen blast furnace process with sintering flue gas injection

In order to achieve ultra-low emissions of SO₂ and NO_x, the oxygen blast furnace with sintering flue gas injection is presented as a promising novel process. The CO₂ emission was examined, and a cost analysis of the process was conducted. The results show that in the cases when the top gas is not circulated (Cases 1–3), and the volume of injected sintering flue gas per ton of hot metal is below about 1250 m³, the total CO₂ emissions decrease first and then increase as the oxygen content of the blast increases. When the volume of injected sintering flue gas per ton of hot metal exceeds approximately 1250 m³, the total CO₂ emissions gradually decrease. When the recirculating top gas and the vacuum pressure swing adsorption are considered, the benefits of recovered gas can make the ironmaking cost close to or even lower than that of the ordinary blast furnace. Furthermore, the implementation of this approach leads to a substantial reduction in total CO₂ emissions, with reductions of 69.13% (Case 4), 70.60% (Case 5), and 71.07% (Case 6), respectively. By integrating previous research and current findings, the reasonable oxygen blast furnace with sintering flue gas injection can not only realize desulfurization and denitrification, but also achieve the goal of reducing CO₂ emissions and ironmaking cost.