Modeling Of Magnesium Extraction From Magnesium Oxide By SOM Process

In recent years, as the price of oil soars upward, scientists have started to focus on other energy sources, such as hydrogen. As magnesium can be used for hydrogen storage by forming MgH2, industry will see a growing demand for the hydride. In hydrogen storage and release cycles using magnesium, hydrogen is released from magnesium hydride through hydrolysis and magnesium hydroxide is produced. Therefore, recycling magnesium hydroxide back to magnesium becomes important. The solid oxide membrane (SOM) process is an emerging technology for this process. In the SOM process, MgF2-CaF2-MgO flux is contained in a stainless steel crucible, which works as the cathode. An ionic-conducting YSZ membrane, connected to a liquid metal anode, is partially immersed in the flux. During electrolysis, when the voltage between anode and cathode is higher than the dissociation potential of magnesium oxide, magnesium ions move toward the cathode and are reduced into magnesium vapor. The oxygen ions move toward the anode, passing through the YSZ membrane. They are then oxidized, forming pure oxygen, CO/CO2 or steam (by reaction with hydrogen). The magnesium vapor, generated at the cathode, is collected in the condenser as high purity magnesium. SOM experiments have been conducted with different liquid metal anodes and without reductants. The SOM technique is a highly energy efficient process and with by-products being oxygen or steam, it is also an environmentally friendly green process. A 2-D electrostatics mathematical model was developed as an initial step towards optimizing the design for a three-tube scale-up SOM electrolysis cell. Several possible geometries were examined to develop the scale-up model and convergence of the model was achieved.