Modeling of Reactions between Gas Bubble and Molten Metal Bath-Experimental Validation in the Case of Decarburization of Fe-Cr-C melts

摘要

A theoretical generic model describing the mass transfer phenomena between rising gas bubbles and a metal bath has earlier been developed by the present authors, to predict the composition change in the melt as consequence of blowing different oxidant gases. In order to verify the model predictions, a series of experiments involving reactions between Fe-Cr-C melts and different O_2-CO_2 gas mixtures were carried out. The results showed that the decarburization deviates significantly from thermodynamic paths predicted on the basis of bulk compositions and that the model was able to make reasonably reliable predictions of the changes of chromium and carbon contents in the melt as a function of time. According to the model, the compositions at the vicinity of injection point as well as at the gas-melt interface in the bubble are likely to be far from that in the bulk. The results of the present set of experiments showed, with CO_2 injection, the utilization of the available oxygen for decarburization was higher as compared to O_2 injection in the case of melts containing higher carbon levels (>1 mass%). Reverse is the case in low carbon melts. The results also indicate relatively less Cr-losses from the metal bath when CO_2 is used as the oxidant. As the model predictions are found to be reasonably reliable, the model predictions are extended to predict the impact of the variation of different process parameters.