A comprehensive model of oxygen steelmaking that includes the kinetics of scrap melting, flux dissolution, slag chemistry, temperature profile of the system, formation and residence of metal droplets in the emulsion, and kinetics of decarburization reaction in different reaction zones was developed. This paper discussed the development and the application of the model into an industrial practice. The results from the model were consistent with the plant data from the study of Cicutti et al. The model suggested that 45% of the total carbon was removed via emulsified metal droplets and the remaining was removed from the impact zone during the entire blow. It was found that the residence time of droplets as well as decarburization reaction rate via emulsified droplets was a strong function of bloating behavior of the droplets. This model is the first attempt in the open literature that allows for the decarburization kinetics of the impact zone to be predicted separately from decarburization kinetics of the emulsion.