Calculation of sulfur removal in ladle furnace unit by means of ionic theory of slags

Abstract This article describes issues of sulfur removal in ladle furnace unit. First of all, metal desulfurization in ladle steel treatment units is achieved due to transition of sulfur to the slag phase. Coefficient of partition of sulfur between metal and slag is affected by sulfide capacity of slag, coefficient of activity of sulfur in the metal, oxidation potential of medium and reaction equilibrium constant of partition of sulfur between metal and slag. Temperature of liquid state in the ladle has significant impact on sulfide capacity of slag. Proposed calculation procedure based on provisions of ionic structure of slags allows evaluating a concentration of sulfur in steel on the basis of determination of coefficient of its partition between metal and slag. Optical basicity is suggested as criterion of refining property of slag, it has been shown that the amphoteric oxide Al2O3 is essential to calculation of this indicator. Its impact on sulfide capacity of slag is detected.