Kinetics of decarburization and oxygen absorption of molten iron of low carbon and oxygen concentrations has been studied. The decarburization and oxygen absorption experiments were performed by blowing Ar-O2 mixture (oxygen partial pressure 1.0×10–5<POs(atm)<5.5×10–2 and gas-flow rate 1000 (and 1900) Ncm3/min) onto the melt surface. The rates of decarburization and oxygen absorption increase with increasing oxygen partial pressure PO2>5×10–3 atm). At oxygen partial pressures of PO2<1.0×10–4 atm, the oxygen concentration is kept almost constant. The total reaction rate of oxygen with the melt (=decarburization rate+oxygen absorption rate) is larger than the rate of oxygen absorption without decarburization and smaller than the rate calculated from a reaction model of oyxgen diffusion in the gas phase. It is presumed that formation of oxide film on the melt surface has an influence on the decarburization and oxygen absorption rates. A mathematical model is proposed to explain the rates of decarburization and oxygen absorption.
