The influence of chemical composition of steel on steel desulphurization

Abstract

The steel desulphurization in ladle furnace depends on temperature, oxygen and sulphur content in the steel, but mainly on chemical composition and physical properties of slag. Necessary requirement for effective desulphurization is also minimum content of easily reducible oxides in the slag. There are many correlations for expression of slag desulphurization capability, where their functional dependency on each other can be found, mainly between sulphur distribution coefficient, optical basicity, basicity, sulphide capacity, desulphurisation potential of slag and also calcium - aluminate ratio of oxides in slag or content of easily reducible oxides in slag. This work presents statistical and graphical correlation between manganese and slag parameters using the set of approximately 768 heats and based on these, the optimal parameters for slag desulphurization capability are expressed especially for steel grades internally marked as OR1, OR3 in Železiarne Podbrezová, a.s. Steel grades OR1 and OR3 were chosen because of difference in manganese content with similar chemical composition of other elements. The MnO content in the slag is one of the most important parameters. Despite the higher scatter of obtained values, the distribution coefficient of sulphur (Ls) is one of the wide range of parameters for whom exists very close dependence on MnO content in slag.