Feasibility of BF Hearth Protection Using Spinel Formation by Slag Composition Control

Abstract

The formation of titanium carbonitride has been used as a conventional method to protect the refractory wear in the hearth. Because titanium carbonitride is formed only in the molten iron, the area that can form a protective layer in the hearth is limited. There is another possibility to protect the refractory wear by introducing the compounds with high melting point in the slags. If the compounds with high melting point are simultaneously formed in the molten iron and slag by adding TiO₂, it might be more effective to form the protective layer and to prevent the refractory wear of hearth. However, the change of slag compositions and the formation of slag compounds can affect the slag viscosity and critical temperature, which might cause serious problems with blast furnace operation.
In this study, to find the slag compositions for the effective compounds formation with maintaining the slag fluidity, the viscosity measurements, in-situ observation of compound formation by a confocal laser scanning microscopy and thermodynamical evaluation by FactSage has been carried out. Based on these results, the suitable slag compositions were suggested to form a protective layer in the hearth.