The Separation Behavior of Impurities in the Purification of High-Purity Magnesium via Vacuum Distillation

Abstract

AbstractMagnesium-based materials with exceptional properties are being widely used in the automotive and aerospace industries, as well as in electronic equipment and Mg-based implants. The development of many advanced engineering structures and precision devices prompts the demand for high-purity Mg with better performance and service. However, the current purification methods meet challenges such as the complex equipment, potential dangers due to the powdery condensed products, and the lack of systematic analysis of the impurity behavior. Here, we report the purification of commercial raw materials into 99.9958% (± 0.0034%) pure magnesium products through one-step vacuum distillation. The process adopts a vertical distillation device, which has the advantages of high recovery efficiency, lumpy condensation products, easy cleaning, and reusability. Experimental results confirm that vacuum evaporation is more effective than vacuum sublimation for the purification of magnesium. Then, the behavior of eight impurities is analyzed theoretically and experimentally. The results significantly verify the difficulty sequence of impurity separation from the Mg base, which is Zn > Ca > Pb > Al > Cu > Ni. The similar equilibrium vapor pressure of Zn and Mg and the separation coefficient close to unity are the reasons that cause zinc to be the most difficult one to be separated. Graphical Abstract