Study on Experiment and Mechanism of Bottom Blowing CO2 During the LF Refining Process

In order to explore the metallurgical behavior and mechanism of bottom blowing CO2 in ladle furnace (LF), CO2 was introduced in the LF refining process. The kinetics and thermodynamics of bottom blowing CO2 were investigated and several mathematical models for kinetic study were established. Some exploratory industrial experiments have been conducted with different proportion of CO2 in a 70ton LF. The results indicated that it could lead to a little oxidation of elements in molten steel with the processing of bottom blowing CO2 compared with Ar stirring. The average oxidation amount of C was in the range of 0.3-0.8kg. The average oxidation amount of Mn was reduced by 0.0067% and the average oxidation of Al was increased by 0.003%, while the mass fraction of FeO was less than 0.5% in the slag hence it could meet requirements of reductive reaction. Mass transfer of CO in bubble interface or chemical reaction was the possible rate-determining step by comparing calculated results with experimental results. Compared with bottom blowing Ar, types and compositions of inclusions have no big change, plus, the equal yield density of inclusions has decreased and the cleanness of steel was improved. Therefore, it is possible to use CO2 in LF.