A computational thermodynamic analysis of atmospheric magnesium production

The Magnetherm process is the most widely used thermal reduction process for commercial magnesium production. This process requires a vacuum atmosphere, ferrosilicon reductant, and dolomite ore. The vacuum atmosphere is typically 0.1 atm. However, the vacuum atmosphere creates two major problems: air leakage and batch operation to tap excess slag. The air leakage contaminates the magnesium vapor and the batch operation lowers productivity. Atmospheric production of magnesium could eliminate the vacuum requirement. By increasing the pressure inside the furnace to atmospheric pressure, a pressure difference would not exist between the outside and the inside of the furnace. Air would not leak into the furnace and excess slag could be tapped without stopping the production. However, the atmospheric magnesium process will require a different reaction temperature and slag composition since under current operating parameters, magnesium cannot be produced when the pressure is over 0.63 atm. A computational thermodynamic analysis was completed on a variety of slag compositions and reaction temperatures. The data collected was used to determine three key factors: (1) purity of the magnesium vapor; (2) aggressiveness of the slag; and (3) fraction of solids in the bulk slag.