Zhuravleva S. Improvement of steel treatment technologies in ladle furnace based on changes in the ratio of the sedimentation and diffusion processes of removing sulfur

The present dissertation paper is devoted to an acute scientific and technical problem of improvements on steel treatment technologies in the ladle furnace based on changes in the ratio of the diffusion and precipitating mechanisms the removal of sulfur. First shown and scientifically proven that removal of sulfur in the ladle furnace occurs by two different mechanisms: - sedimentation of sulfur in melt by sulphide-former elements to form a sulfide or oxysulfide of endogenous non-metallic inclusions and the subsequent removal of these impurities in slag; - diffusion of the sulfur from the metal in the slag at the phase boundary. Part of each mechanism in the desulfurization process was defined. First based on data of experimental melts and theoretical calculations of apparent activation energy the critical concentration of sulfur for change kinetic regimes of desulfurization process in LF considering the precipitating action and diffusion mechanisms of sulfur removal was determined. It was shown for the first time that the desulphurization degree in LF of different capacity depends on the initial sulfur content with the exponent n = 0,3. First defined quantitative effect of stirring power on metal desulphurization in treatment conditions in LF of different capacity. The degree of desulfurization increases with the stirring power in the form of a power function with the exponent n = 0,2. It was shown for the first time that the system deviation from the sulfur equilibrium is directly proportional to the time of complete mixing. The proportionality coefficient decreases with the ladle capacity. Quantitative characteristics of the impact of major technological factors on metal desulfurization and system deviation from equilibrium for ladle furnace of different capacities were defined. It is the first time the statistical models of joint influence a slag composition and temperature on the desulfurization degree in LF were obtained. Found that for low-iron slags of LF the method of calculating the equilibrium between the metal and sulfur slag based on the theory of ionic structure of liquid slags is the most appropriate.