Abstract
Abstract To study the final equilibrium state and process of CO2 injecting into the Fe–C melt with different initial carbon contents, a model was established based on the method of minimization of Gibbs free energy and the corresponding experiments were carried out in a high-temperature tube furnace. When CO2 is continuously injected into the Fe–C melt at 1873 K, the final equilibrium state of the system is such that the carbon and oxygen contents in the melt are 0.1977 and 0.0115 wt pct, respectively, and the volume ratio of CO in the gas phase is 85.75 vol pct. When the initial a [O] × a [C] in the melt is greater than those in equilibrium with CO under 0.8575 atm, the CO2 gas removes carbon from the melt. On the contrary, the role of CO2 gas is to add carbon and oxygen to the melt. At the same time, the variation of carbon and oxygen with time obtained by experiments was different from the theoretical calculation at extremely low carbon content, which requires further study.
Highlights
AS a gaseous medium, CO2 is widely used in steelmaking processes as a replacement for O2/N2/Ar gases
The preceding studies mainly focus on the industrial applications and decarburization kinetics of CO2 gas used as an oxidant and stirring gas; the final equilibrium state of the system is not clear when CO2 is continuously injected into the Fe–C melt, and it needs to be clarified whether CO2 shows a decarburization effect
Based on the thermodynamic calculation and experiments in the laboratory, the final reaction equilibrium state and process were studied by injecting CO2 into the Fe–C melt under different initial carbon contents
Summary
AS a gaseous medium, CO2 is widely used in steelmaking processes as a replacement for O2/N2/Ar gases. At present, it is being used for the combined top and bottom blowing in the basic oxygen furnace (BOF) and bottom blowing in the electric arc furnace (EAF). Theoretical analyses and laboratory experiments were carried out in an argon-oxygen decarburization furnace (AOD) and a vanadium-extraction converter (de-V BOF), which can reduce the amount of dust and the total Fe content (TFe) in the slag and improve the dephosphorization efficiency. CO2 can improve the purity of molten steel in the LF and the stirring strength in the RH, and realize selective oxidation of chromium, vanadium, and other valuable elements with carbon.
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