Synthesis MgAl₂O₄ Spinel From Aluminum Dross And The Application In Al₂O₃-MgAl₂O₄ Refractory

The aluminum dross generated while melting aluminum has many impurities. In this article the content of aluminum dross was tested using the X-ray diffraction, X-ray Fluorescence Analysis, Chemical analysis and Nitrometer.The result showed the presence of the following components (with the indicated numbers being wt%): Al 26.5,AlN 16.69,Al₂O₃ 6.23,NaCl 4.32 , MgAl₂O₄ 22.17 , SiO2 5.16 , CaO 2.36 , TiO2 5.75 ,Fe2O33.49.According to the contents of aluminum dross and the high temperature smelting theory, MgAl₂O₄ was prepared using aluminum dross, bauxite and magnesia as raw material, carbon and iron as accessory. The two steps electric melting method was used in synthesizing the MgAl₂O₄. The results indicated that MgAl₂O₄ synthesized by aluminum dross gained better the properties than bauxite based MgAl₂O₄. The MgAl₂O₄ had the best comprehensive properties when the aluminum dross addition was 40%. The XRD of MgAl₂O₄ show there was Calcium hexaluminate formation when the addition of aluminum dross was 40% and 60%.In order to test the properties of MgAl₂O₄ made by aluminum dross using as raw refractory material, the Al₂O₃- MgAl₂O₄ refractory was prepared and developed for refining aluminum furnace. The physical properties at room temperature and microstructures of the different components of the Al₂O₃-MgAl₂O₄ composite material were investigated using national testing standards. The effect of the Al₂O₃-MgAl₂O₄ composite material on high purity aluminum was also studied through the static crucible method. The results indicate that the specimens form a dense structure when treated at 1650℃for three hours, and synthetic MgAl₂O₄ is found in the matrix. Better cold physical properties can be obtained when the ratio ofα-Al₂O₃ and fused magnesite in the matrix is 2:1, and this ratio results in limited contamination the molten aluminum. The aluminum corrosion resistance was studied by 7075 melted alloy and melted high pure aluminum at different temperature. The specimen made by MgAl₂O₄ synthesized by aluminum dross gained good aluminum corrosion resistance.