| Abstract: | A model of desulphurisation of steel with gaseous calcium bubbles based on a population balance equation is presented. The equation is a basis of the quantitative approach to the phenomena observed in the dispersive systems. The course of reaction of the calcium bubbles with the oxygen and sulphur during the Stokes float-out was studied for various model parameters. The effect of the following factors on the refining process efficiency was considered: interval of bubble sizes, distribution of bubble sizes and participation of a carrier gas. It was found that the refining process is affected mainly by the global bubble surface and the residence time of bubbles in the steel. It means that the bubble size interval and size distribution of the bubbles for the calcium mass is a decisive factor for the desulphurisation efficiency. Any increase in the carrier gas content, in fact, increases the bubble surface, yet, simultaneously accelerates the float-out of the not reacting bubbles. Thus, for the Stokes model the effect of a carrier gas on the desulphurisation efficiency is small. The comparison of the calculated and experimental results for different blowing depths and different amounts of calcium is presented. |
