The separated estimation of the reaction rate at bath surface (surface reaction) and at Ar bubble interface flotating in the bath (bubble reaction) was achieved by the measurements of gas adsorption and desorption rate. The influence of various factors on the surface reaction rate of gas and liquid reaction under the gas stirring condition was investigated for water and molten steel systems. The following points were clarified :
1)The ratio of surface reaction rate to the bubble reaction rate for N2-molten steel system is much larger than that forO₂-water system.
2)Most of the surface reaction occurs at the flotating area of Ar gas bubbles at the bath surface (activated surfacearea).
3)The surface reaction rate increases in propotion to one-second power of Ar gas flow rate and in inverse propotion to two-third power of the pressure. In addition, it is strongly influenced by the gas injection depth.
4)The surface reaction rate well corresponds to the newly introduced parameter for the N₂-molten steel and O₂-water system, considering the activated surface area, gas flow rate, pressure and gas injection depth.