Preparation process of α-Al₂O₃ from secondary aluminum dross

The preparation of α-Al₂O₃ with a process of low-temperature alkaline melting,leaching and seed precipitation was explored by using secondary aluminum ash as a raw material.A series of experiments were done to investigate the effects of factors such as alkali-to-dross ratio,salt-to-dross ratio,smelting temperature,smelting time,leaching temperature,leaching time and solid-to-liquid ratio on the leaching rates of Al and Si.The feasibility of using seed precipitation as a successive treatment technology of leachate to prepare alumina was discussed.The optimum conditions of the process were determined as follows:alkali-to-dross ratio 1.3,salt-to-dross ratio 0.7,smelting temperature 500℃,smelting time 60 min,leaching temperature 60℃,leaching time 30 min,and solid-to-liquid ratio 1:4.The leaching rate of aluminum can reach to 92.71%.It is indicated that seed precipitation as a successive treatment technology of leachate is feasible and effective.