Synergistic Optimization of Carbon Emissions and Economic Performance in Stainless Steelmaking Using CO ₂ as an Auxiliary Oxidant

This article explores low‐carbon pathways for stainless steelmaking by focusing on 400‐series stainless steel and developing an integrated model that combines mass–energy balance, carbon‐emission accounting, and economic assessment. The model is used to evaluate the comprehensive effects of employing CO 2 as an auxiliary oxidant in smelting. Results show that CO 2 can partially substitute for O 2 and N 2 while enhancing bath stirring, thereby reducing chromium oxidation losses; at a 7.5% injection ratio, ferrosilicon and lime consumption decrease by 11.8% and 8.6%, respectively. However, the strongly endothermic CO 2 ‐[C] reaction lowers the melt temperature by up to 18.1 K, requiring reduced scrap and increased raw material input, which partly offsets emission‐reduction gains. Carbon‐emission analysis reveals a dual effect: without considering cooling, emissions per ton of steel decline by 13.0%, whereas with cooling, net reductions remain but with reduced magnitude. Economic evaluation indicates that the viability of this technology is highly sensitive to carbon‐pricing policies; under carbon taxation, its emission advantage translates into economic benefit, enabling joint environmental and economic optimization. Building on these findings, an internal recirculation scheme is proposed, which captures and reuses CO 2 from the process off gas, presenting a feasible and economically promising pathway toward near‐zero‐carbon stainless steelmaking.