Influence Of Vitreous Silica And ρ-Al₂O₃ On The Performance Of The Magnesian Slag Trap In Tundish

The effect of addition of fused silica, andρ-Al₂O₃ on magnesia tundish weir was investigated through the MgO-Al₂O₃-SiO₂ phase diagram in this paper. In the first part, fused silica of different grain size with low thermal expansion coefficient was added into the magnesia material to improve its thermal shock resistance using the micro powder silica as the binder. The thermal shock resistance of magnesia castables is able to be improved by adding fused silica, the effect of adding fused silica particle is significantly better than that of fused silica powder. With the increase of the melting quartz content, the slag corrosion resistance to high CaO/SiO₂ ratio capacity gradually increases. And capacity of slag penetration resistance gradually diminishes, the effect of addition fused silica particles are better than that of adding fused silica powder. On the base of the former research, the second part in this paper usesρ-Al₂O₃ as a binder to replace part of micro silica in order to reduce the silicon content of host material. Addition of suitable fused silica particles help to improve the capability of penetration resistance and corrosion resistance of higher CaO/SiO₂ ratio, the erosion and penetration depth decreased by 2.84mm and 3.44mm after experimentation; but the effect of capability of penetration resistance and corrosion resistance of lower CaO/SiO₂ ratio is not obvious. In the third part, in order to improve corrosion resistance, the author uses brown corundum powder replacing magnesia powder and adds some magnesia-alumina fined powder to generate MA. It is more effective on the lower CaO/SiO₂ ratio tundish slag than that of the higher CaO/SiO₂ ratio tundish slag about performance of penetration resistance and corrosion resistance. In the fourth part, the slag penetration resistance is analyzed by SEM, its conclusion is: the volume increased following the produce of M2S and MA, on the one hand it may seal up the blowhole, on the other hand it may form the micro crack with properly quantity and size. The micro crack can prevent the crack expanding and enhance its thermal shock resistance stability. The magnalium spinel may massively absorb FeO, MnO in the dregs to form the unlimited solution to enhance the slag viscosity, Al₂O₃ can absorb CaO in the dregs to further enhance the viscosity of the dregs, it is better to suppress tundish steel corrosion and permeating to the samples.