China Nonferrous Metallurgy

The desalted aluminum ash produced by the wet aluminum process is used as experimental raw materials. Alkaline roasting technology is used to treat the desalted aluminum ash to produce raw materials for electrolytic aluminum, improving the recycling value of the desalted aluminum ash, and realising the recycling of aluminum in the aluminum industry. Firstly, the theoretical feasibility of roasting treatment technology was analyzed from the perspective of thermodynamics, and the change of Gibbs free energy of α-Al₂O₃, MgAl₂O₄ and Na₂CO₃ reactions under different temperature conditions was investigated to determine whether chemical reactions occurred and the conditions of occurrence. The theoretical analysis results were verified experimentally by X-ray powder diffraction technology. On this basis, the effects of Na2CO3 dosage, roasting temperature and roasting time on aluminum recovery were studied. The results show that α-Al₂O₃ MgAl₂O₄ and Na₂CO₃ in desalted aluminum ash can react with Na₂CO₃ to produce sodium aluminate above 1000℃. Under the experimental conditions of roasting temperature at 1000℃, mass ratio of Al∶Na₂CO₃ at 1∶2 and roasting time at 3.5h, the highest recovery rate of aluminum can reach 97.08%. It is feasible to recover aluminum from desalted aluminum ash by alkaline roasting, which is an effective way to recycle aluminum ash.