Fluid Bed Dehydration of Magnesium Chloride

Abstract

Molten salt electrolysis of M_gCl₂ is commonly used for the production of magnesium metal. However, the electrolysis feed must be completely dry with minimum oxygen content. Therefore, complete dehydration of the M_gCl₂ brine or the hydrated prill is a required process, which is very challenging because of the ease of thermal degradation due to hydrolysis of magnesium chloride.

Fluidized bed dryers are often used, under hot air and HCl environments. The key features of three different types of fluid bed technologies, which can be applied to M_gCl₂ dehydration plants, are described in this paper. In addition, a discussion of chemistry, unit operations and advantages associated with each option, is presented.

The background information is provided based on open literature sources, including papers and patents. Most calculations are performed using commercially available metallurgical software, for the thermodynamic calculations and mass/heat balances.