Opportunities to reduce energy consumption and CO₂ emissions from ironmaking blast furnace using CO₂ electrolysis to CO for carbon recycling

• Published in: Journal of cleaner production 2023-02, Vol.389, p.135997, Article 135997
• Main Authors: Hu, Yichao, Rufford, Thomas E., Chen, Jian, Hao, Liangyuan, Li, Mengran, Qiu, Yinxuan, Garg, Sahil, Rudolph, Victor, Wang, Geoff
• Format: Article
• Language: English
• Subjects: Blast furnace ironmaking; Carbon recycling; Coke saving potential; CO₂ electrolysis; CO₂ emission
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2023.135997

The blast furnace (BF) ironmaking is an energy-intensive process and the largest source of CO₂ emissions in an integrated steel mill. We evaluated the potential energy, fresh coke savings and associated reductions in CO₂ emissions for a BF operation if some CO₂ in the BF gases were converted to CO using an electrochemical CO₂ conversion process and that CO was recycled to the BF. As an added benefit, the electrochemical process produces H₂ and O₂, which helps iron ores reduction and oxygen enrichment. This paper presents a mathematical model of BF that integrates CO₂ capture, CO₂ electrolysis, and gas injection. Our results show that integrating a CO₂ to CO electrolysis process in a traditional ironmaking plant could reduce coke consumption from 386 kg/tHM to 260 kg/tHM at a 9% oxygen enrichment rate. A maximum 40% reduction in the CO₂ emissions per ton of hot metal can be reached. However, the total energy consumption of the process increases when the CO₂ electrolysis unit is included. Consequently, realising these potential CO₂ savings requires the availability of zero-carbon electricity from renewable sources. Improvements in the selectivity and efficiency of the CO₂ electrolysis in the future may enhance the overall economics and efficiency of this process. •The BF ironmaking process integrates CO₂ capture and electrolysis conversion.•A mathematical model is proposed for the BF process applying CO₂ electrolysis.•The BF ironmaking process operates towards optimised coke rate, CO₂ emission, and energy consumption.•CO₂ emission of the process can be decreased by up to 40%.