Development of a calculation method for evaluating technological parameters of the desulphurization process in a ladle

To fulfil the requirements for pipe steels of strength group D in terms of sulfur content, the metal is subjected to ladle desulfurization. In the course of desulfurization, in order to reduce its duration, steel is mixed in the ladle by blowing with argon. To optimize the desulfurization process, a methodology has been developed for evaluating its technological parameters, which allows determining under production conditions the intensity of steel blowing in the ladle. As initial data for comparative calculations of the technological parameters of the process of desulfurization of pipe steel in a ladle according to the developed method, the indicators of industrial melts were used, including the chemical composition of steel and the main technological data characterizing the production parameters of desulfurization of pipe steels of strength group D. The algorithm for using the proposed technique provides for the calculation of sulfur activity and the coefficient of sulfur activity in a steel melt of a given composition; determination of the oxidizing potential of the slag-metal system and the sulfide capacity of the slag; calculation of the equilibrium sulfur distribution coefficient between steel and slag, as well as the volumetric mass transfer coefficient under equilibrium and production conditions. To determine the thermodynamic characteristics of the interaction of sulfur dissolved in a metal with slag, the sorption ability of the slags of the analyzed melts with respect to sulfur was calculated. Data are presented on the effect of sulfur activity in experimental melts on the final sulfur content in steel. The rational limits of the value of the integral indicator of the composition of refining slags and volumetric mass transfer coefficient, which provide the best indicators of the process of desulfurization of steel, were determined. The dependences of the influence of the volumetric mass transfer coefficient on the duration of the process and the final sulfur content in the metal were established. The proposed methodology for assessing the technological parameters of steel desulfurization can optimize the duration of its individual stages and, thereby, reduce the cost of the process as a whole.