Process model for manufacturing 400 series stainless steel with purified CO2 as an auxiliary oxidant and realizing carbon cycle

Abstract

To reduce the CO2 emission in the iron and steel industry, aid carbon neutralization, and promote the application of CO2 in stainless steel production, CO and CO2 in flue gas were separated and purified to recycle for the production. Further, a process model of smelting stainless steel with O2–CO2 mixed injection was established based on the theory of thermodynamics and kinetics. The model validation was conducted in a 70 ton-stainless steel smelting furnace. The model calculation showed that CO2 injection for smelting stainless steel can improve the reaction efficiency of various elements in molten steel and cause a temperature drop. However, the excessive CO partial pressure in the molten pool caused by injecting CO2 aggravated the oxidation loss of chromium and led to a sharp rise in the temperature of molten steel near the end of smelting. According to the guidance of the model, a carbon cycle process concept was designed to realize the internal circulation application of CO2 in stainless steel production, which improves stainless steel smelting efficiency and self-consumption of CO2 produced by smelting.