Reaction Mechanism Between CO₂ Bottom-Blowing Gas and Fe–Si/Mn/Al–C Melt

Molten steel used in the refining processes contains large amounts of alloy elements, such as Si, Mn, and Al. Similar to that in the Fe–C melt, the effect of CO₂ in increasing the carbon and oxygen contents in melt-containing alloys determines its suitability as a bottom-blowing gas for refining processes. In this study, the reaction mechanism between CO₂ and Fe–Si/Mn/Al–C melt at 1600 °C was analyzed. During the early stages of smelting, CO₂ released carbon and oxygen into the melt. After reaching the critical composition of the melt, CO₂ stopped releasing carbon into the melt, while continuing to decompose and release oxygen atoms, resulting in the oxidation of the alloy and carbon elements in the melt. Furthermore, this study investigated the reaction between CO as the bottom-blowing gas and the Fe–Si/Mn/Al–C melt, which established the partial dissolution of CO generated by the decomposition of CO₂ released carbon from the melt. Consequently, the reaction of CO₂ with an Fe-based melt was further confirmed to include the decomposition of CO₂ into CO and oxygen, and equilibrium reaction of CO with carbon and oxygen.