Recovery of Az91d Magnesium Alloy Waste by Vacuum Gasification - Directed Condensation

Magnesium alloys, known as "green engineering material in the 21st world" and "revolutionary medical metal material", have been widely used. However, in the process of production and consumption, a large amount of waste is generated, which not only pollutes the environment, but also wastes secondary resources. Therefore, the vacuum gasification - directed condensation method was adopted in this study, and the waste of AZ91D magnesium alloy was taken as the representative for recovery. The vapor pressure and separation coefficient of main metal magnesium and impurity were calculated. The three-phase diagram of magnesium and mechanism of molecular motion under vacuum was analyzed to determine vacuum vaporization process for the recovery of magnesium scrap, and the distribution of volatile condensing heat field of volatile impurity Zn and Mg was simulated. The effects of system pressure, temperature and holding time on the purity of recycled magnesium alloy were investigated experimentally. The results show that the optimal experimental conditions were pressure 100 Pa, distillation temperature 1073 K, condensation temperature 873 K and holding time of 60 min. The final purity of magnesium can reach 99.96%. This study provides a good theoretical and practical basis for the vacuum recovery of complex magnesium alloy waste.