Analysis of the mass transfer in the ladle refining of steel with gas mixing is of great importance in order to intensify such processes and improve the overall productivity of steel plants. Traditional analysis of process data does not permit the assessment of current production conditions. In the approach here adopted, the dynamics of steel refining with gas mixing is characterized by a bulk mass-transfer coefficient. On the basis of extensive industrial data for the slag desulfurization of lowand moderate-carbon steel in the ladle–furnace unit and vacuum treatment to remove nitrogen in the VD unit, together with models of the mixing and refining processes, new relations between the rate of gas injection in mixing and the bulk mass-transfer coefficient are derived for open ladle processes and for vacuum degassing. Models of refining based on those formulas prove effective.