The master’s thesis examines the electrolysis of molten MgCl₂ as an alternative, energy-efficient, and environmentally more acceptable method of magnesium production compared to the currently dominant Pidgeon process. The focus is on the development and testing of a new reactor design, in which the reaction vessel simultaneously serves as the cathode, while the anode is inserted from the top of the reactor. The introduction presents the broader context, including the transition to a low-carbon society and the need for sustainable metal production for energy storage and industrial applications. Magnesium is a light, strong, and abundant element, widely used in the automotive, aerospace, and electronics industries, but high production costs remain the main limitation to its broader application. The central problem of electrolytic magnesium production is the presence of magnesium oxide in the feedstock, as it leads to the formation of sludge and lower process efficiency. Various industrial processes are reviewed, from early experiments with MgO to established processes such as Dow, I.G. Farben, and Norsk Hydro, as well as thermal methods like Pidgeon and Magnetherm. While the Pidgeon process is based on silicothermal reduction of dolomite and causes significant CO₂ emissions, electrolytic methods offer a cleaner process but require the costly preparation of anhydrous MgCl₂. A dedicated section addresses the removal of impurities and the problem of MgCl₂ dehydration, which is often solved by introducing HCl gas or through carbochlorination. The experimental part describes the construction and use of a custom-made reactor. The electrolysis experiment lasted two hours at 800 °C and a constant current of 20 A. Electrode stability was confirmed by voltammetric measurements, while oxidation and reduction occurred at potentials consistent with the theoretical values for the formation of chlorine and magnesium. The presence of chlorine gas was qualitatively confirmed using litmus paper. Analysis of the samples with scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) showed that the product was mainly Mg (around 70 %), with traces of oxidation and minor amounts of Fe and Co, indicating partial reactor corrosion. The results confirm that the reactor concept is feasible. The formation of magnesium and chlorine was successfully demonstrated, while challenges such as product oxidation and corrosion of steel components were also identified. The thesis opens possibilities for further process optimization, particularly in reducing energy consumption, improving efficiency, and integrating renewable energy sources. Thus, the electrolysis of molten MgCl₂ represents a promising pathway for sustainable magnesium production in the future.
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