A method and system for crystal pulling from a growth melt that is produced by molten oxide electrolysis are presented. The method may be used as a purification step in processing raw feedstock such as lunar regolith. The Czochralski technique is a similar, but substantially different, process of crystal pulling from a growth melt. In the Czochralski technique, the growth melt is a very pure liquid of the element that is to be formed into a single crystal. In embodiments described herein, the growth melt is substantially impure and may be a combination of two or more elements having similar concentrations, even though only one of the elements is to be formed into a single crystal.

A method and system for producing and collecting oxygen gas using molten oxide electrolysis is presented. The system includes a refractory vessel to hold molten oxide material, an anode, a cathode, and a thermionic diode at a top portion of the refractory vessel. The anode for the electrolysis cell (e.g., the anode and cathode that are positioned in the vessel to perform electrolysis) has a dual function by also acting as the cathode of the thermionic diode. Among other things, the presence of the thermionic diode may limit the direction of electrical current flow so that current only flows from the anode to the cathode of the electrolysis cell. This directional limitation provides an advantage in that an AC power source of the MOE system need not be rectified or converted to DC before powering the MOE system.

A process for recovery of rare-earth metals from magnet scrap includes leaching a rare-earth metal containing magnet scrap with halogen acids to form an aqueous leachate solution that includes rare-earth metal halides, at least partially dehydrating the aqueous leachate solution to form a dehydrated or partially dehydrated rare-earth metal halide feedstock, and electrolyzing the dehydrated or partially dehydrated rare-earth metal halide feedstock by molten salt electrolysis to form rare-earth metal and halogen(s).