The Effect of the MgO Content of Slag on its Penetrability into the Refractory Lining in a Ferrochrome Converter

Abstract

The refining of ferrochrome with a ferrochrome converter permits the use of molten ferrochrome in an integrated stainless steel mill. During this process, the carbon and silicon contents of the ferrochrome are reduced using oxygen-blowing. To keep the slag liquid and maintain its compatibility with the employed refractory lining, the composition of the slag needs to be modified by slag former additions to compensate for the formation of SiO2. The objective of this work was to study the effect of the MgO content of slag on the penetration of the slag into the refractory lining. The reactivity between the slag and the refractory lining was studied by comparing the reactivity in high-temperature crucible experiments. The MgO and CaO stabilized slag was compared to MgO saturated slag which wears the magnesia lining less. The results of the experiments suggest that the refractory wear can be reduced by increasing the MgO content of the slag. The reduced refractory wear was verified in an experimental campaign conducted at Outokumpu Stainless Oy in Tornio, Finland. Consequently, it is concluded that modifying slag with dolomite lime can lead to significant economic benefits.