| Calcium aluminate flux is a new kind of pre-fused steel refining agent. It is widely used in iron&steel industry because of its functions of desulfurizing and deoxidizing of steel and submerged arc heating and good properties of steel cleaning and gas absorbing. According to other people’s studies, most researches are mentioned on calcium aluminate flux of CaO-SiO2-Al2O3system and application studies are focused on refining effects of flux blended with lime and fluorite at a certain ratio to steel. And the CaO-MgO-Al2O3-SiO2system flux did not fully investigated. In this article, melting properties, steel refining effect and erosion mechanism to MgO-C bricks of calcium aluminate flux with different MgO content are studied.Good melting properties of flux could guarantee modern efficient refining process by ensuring fast melting of flux in process and quick homogeneous slag forming. Softening temperature, hemispherical fusion temperature, flowing temperature and melting rate of CaO-MgO-Al2O3-SiO2slag system are studied by orthogonal experiments in this article. The prominent factors effecting flux melting properties are constituents of SiO2and MgO and constituents of CaO and Al2O3are the second effecting factors. The optimum combination is that SiO2is around3%, MgO should be less than12%, CaO is around45%and Al2O3is around40%. According to the conclusion, calcium magnesia aluminate flux with different contents of MgO from1%to16%is pre-fused and produced. And the hemispherical fusion temperature of these fluxes are less than1350℃.Stimulate LF process by using electric induction furnace to compare different desulfurization effect of calcium magnesia aluminate flux to Al-killed steel. The optimum constituent of calcium magnesia aluminate flux with above70%desulfurization rate is that SiO2is around5%, MgO is less than10%, Al2O3is around40%and CaO is in the range of45%to55%. Effects of calcium magnesia aluminate flux with different MgO contents to steel inclusions in refining process are discussed. With the increasing of MgO content in calcium magnesia aluminate flux, average size of inclusion showed us the "N" trend. And the MgO content in spinel inclusions is decreased and is closed to the liquid range under1600℃comparing the calcium magnesia aluminate flux with fluorite and bauxite. Fluorite would bring large-scale inclusions. obove20μm, comparing to calcium magnesia aluminate flux.In order to slacken the slag erosion to magnesia carbon brick and improve the work life, calcium magnesia aluminates flux are studied and comparied with the traditional process using fluorite, calcium magnesia aluminate flux is performed with less erosion than the fluorite and the erosion is decreased with the increasing of MgO content in flux. And the reative erosion rate is lower about30%than the fluorite. Firstly slag dissolve and erode magnesia carbon materials until MgO content reached the8%saturability in the final slag. Then as the dynamic stirring from final slag to magnesia carbon materials, magnesia particles are eroded gradually to get the20%MgO content in the slag and then the magnesia carbon bricks are eroded.The industrial deep desupfurization trial showed that:the pre-fused calcium magnesia aluminates flux is45-55%CaO,34-44%Al2O3,6-12%MgO,<5%SiO2,<1.0Fe2O3,<0.2F and <0.1%S. This can get final steel desulfurization rate above90%which is higher than the current70%with the cuurent mechanical mixed flux. And the final slag has the good0.003-0.004slag sulfur capacity, the steel inclusions get the technical target with A, B, C, D and DS which are less than1.0. |
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