Interaction Between Slag And Magnesia-spinel Composite

Periclase-spinel refractories is stable in reduction and oxidation condition, good durability and no Cr6+ environmental pollution problems, so it is widely used in cement kiln, glass furnace regenerator, steel ladle lining, lime kiln and so on. However, there is no systematic comparison about corrosion process under different conditions. In this paper, spinel prepared by different way was introduced into magnesia-spinel materials to discuss their differences in physical properties and slag corrosion mechanism.First of all,differences in physical properties of different magnesia-spinel material are studied,the results show that the in situ synthesis MgAl2O4 in the materials will optimize the matrix structure, but differences of expansion coefficient between periclase and corundum will cause more micro cracks, thus reduce the density of the material, causing a large linear change and high apparent porosity, thereby reduce the material from the structure of anti-erosion ability.Secondly, effects of different C/S ratio of CaO-Al₂O₃-SiO₂ system on slag corrosion of magnesia-spinel materials are researched, furthermore, FactSage thermodynamic software was used to simulated the processes. The results show that periclase-spinel materials show high resistance ability to high basicity slag. Low melting silicate slag penetrate into the material mainly along the matrix phase and grain boundaries. The MgO substrate particles dissolved into the slag and reacted within the Al₂O₃ in the slag to form secondary spinel at the interface of slag/Refractory; slag containing CaO, SiO₂ materials continue to penetrate into the inner and form Ca₃MgSi₂O₈, Ca₂SiO₄, Ca₂SiO₄, Mg₂SiO₄ and other phases. Ca₃MgAl₄O₁₀ phase appears in the calculation of FACTsage, but not found in the microstructure observation of the sample; Ca₃SiO₅ phase appears in the microstructure,but does not appear in the calculation.When Fe₂O₃, magnesium and other impurities ae added into the slag, magnesia will absorb the Fe₂O₃ slag formats MgFe₂O₄; Added MgO will react Al₂O₃ in slag to form 2⁴μm MgAl₂O₄ particles, which fill in the periclase particles as the slag flows. Thereby, reduces the slag flow rate, lowers the corrosion rate.