Effects of Metallization Degree of DRI on the Yield and CO₂ Emission in Reduction Shaft Furnace Process

Reduction shaft furnace process is one of the future directions for low-carbon ironmaking. Different parameters can affect the yield and CO₂ emissions. In the present work, the effect of metallization degree (MD) of direct reduced iron (DRI) on the yield and CO₂ emission in reduction shaft furnace process was calculated by thermodynamics, considering the partial oxidation of coke oven gas (COG). The results indicate that (1) at a reduction temperature of 850 °C and an MD of 90%, COG partial oxidation in shaft furnace can increase DRI yield by 0.266 kg/100mol COG and reduce CO₂ emissions by 72.664 kg/t-DRI compared to heating furnace; (2) reducing reduction temperature and MD will increase DRI yield and reduce CO₂ emission. At 800 °C with a 90% MD, the highest DRI yield (2.599 kg/100mol COG) and lowest CO₂ emission (626.406 kg/t-DRI) were achieved, which mark a significant 0.138 kg/100mol COG increase in DRI yield and a notable 43.331 kg/t-DRI decrease in CO₂ emission compared to 950 °C with a 100% MD; (3) high CO₂ removal rates from the top gas not only slightly reduces the heat load of the heating furnace but also provides more heat and reducing gas for top gas recycling. The results of this study may provide guidance in selecting optimal parameters for practical shaft furnace processes and reducing CO₂ emissions.