China Nonferrous Metallurgy

Aluminum dross is a solid waste produced in the electrolytic aluminum and recycled aluminum processes. Its main components are metallic aluminum, alumina, aluminum nitride and magnesia-aluminum spinel. By regulating the phase composition content of aluminum dross, magnesia-aluminum spinel materials can be prepared by solid-phase sintering. Rare earth oxides can promote the sintering densification and grain development and growth of magnesia-aluminum spinel materials. This study investigated the influence of trace doping of four rare earth oxides (Y₂O₃, Eu₂O₃, La₂O₃ and CeO₂) in the raw materials for preparing magnesia-aluminum spinel materials using aluminum ash slag on the performance of sintered materials. And the microscopic mechanism of rare earth oxides during the enhanced sintering process was explored, and the following main conclusions were obtained. The results show that Doping with four rare earth oxides (Y₂O₃, Eu₂O₃, La₂O₃ and CeO₂) can enhance the density performance of magnesium-aluminum spinel materials prepared by sintering aluminum ash. Magnesium-aluminum spinel materials were obtained by doping 3%Y₂O₃, 3%Eu₂O₃, 3%La₂O₃ and 3%CeO₂ in aluminum ash and sintering at 1673K for 3 hours. The volume density of the material changed from 2.02g/cm ³ to 2.04, 2.02, 2.13 and 2.07g/cm ³ respectively. The compactness effect of the sintered body strengthened by La₂O₃ doping was better than that of the other three types. During the doping and sintering process of rare earth oxides with large ionic radii, rare earth ions undergo solid solution diffusion. This diffusion process accelerates the elimination of pores, thereby promoting the sintering of spinel materials. The effect of different rare earth oxide doped aluminum ash slag on improving the density of magnesium-aluminum spinel materials prepared by sintering varies. Among them, the isomorphic displacement effect significantly enhances the density of the material. Aluminum-ash slag is a solid waste produced in the process of electrolytic aluminum and recycled aluminum. By regulating the phase composition of aluminum-ash slag, magnesia-aluminum spinel materials can be prepared by solid phase sintering. At the same time, the effect of doping modification of rare earth oxides on the density of materials is studied. The results show that doping of four kinds of rare earth oxides (Y₂O₃, Eu₂O₃, La₂O₃ and CeO₂) can improve the densification properties of MgAl₂O₄ spinel materials prepared by sintering of aluminum-ash slag. The bulk density of MgAl₂O₄ spinel was changed from 2.02g/cm³ to 2.04, 2.02, 2.13 and 2.07g/cm³ by sintering of 3%Y₂O₃, 3%Eu₂O₃, 3%La₂O₃ and 3%CeO₂ doped aluminum-ash slag at 1673K for 3h. La2O3 doping enhances the densification of sintered body better than other 3 types. Rare-earth oxide doping sintering with large ion radius makes rare-earth ion solid solution diffusion, diffusion accelerates the elimination of pores and promotes the sintering of spinel materials. Different rare-earth oxides doped alumina ash have different effects on the densification of MgAl₂O₄ spinel materials prepared by sintering, and the densification is stronger by isomorphic substitution.