Effects of Mineral Raw Materials on Melting and Crystalline Properties of Mold Flux and Mineralogical Structures of Flux Film for Casting Peritectic Steel Slab

During peritectic steel continuous casting, mold flux properties and flux film structures play significant roles in controlling slab quality. In this study, mold fluxes and flux films for casting peritectic steel slab were obtained using mineral raw materials such as quartz, wollastonite, fluorite, soda ash and others. The effects of mineral raw materials on mold flux properties and flux film structures were investigated through the measurement of melting point, viscosity, crystallization temperature, critical cooling rate, crystallization ratio and crystalline phase content. The results indicated that with increasing the quartz addition (16 to 24 mass%) and the wollastonite addition (11 to 19 mass%) in mineral raw materials, the melting point, viscosity and wollastonite content of flux film increased, while the crystallization temperature, critical cooling rate, crystallization ratio and cuspidine content of flux film decreased. The melting point, viscosity and wollastonite content of flux film reduced with increasing the fluorite addition (8 to 16 mass%) and soda ash addition (10 to 18 mass%) in mineral raw materials. Furthermore, compared with soda ash, the fluorite predominantly enhanced the crystallization temperature, critical cooling rate, crystallization ratio, cuspidine content of flux film. In addition, it was showed that the heat transfer performance and the slab quality might be primarily attribute to the crystallization ratio and cuspidine content of flux film. These results provided a theoretical foundation for optimizing the mold flux of the peritectic steel and were vital to improving the slab quality.