Uranium molten, density

During the electrorefining of uranium metal in a molten salt eutectic, a low current density favors the formation of large single crystals. Up to 5-cm single crystals of uranium metal have resulted from the large-scale (100 kg of U) electrorefining of uranium metal in molten LiCl/KCl eutectic (17). 

The Density of Molten Thorium and Uranium Tetrafluorides. J. Inorg. 

The reaction of Ca° with UF4 is sufficiently exothermic that both Cap2 and U° reaction products are molten the equivalent Mg reaction is less exothermic, so the reaction must be initiated at an elevated temperature to result in molten products. CaF2 and Mgp2 are not soluble in molten uranium, so the reaction produces a dense metallic uranium phase and a lower-density salt phase unreacted starting materials are more soluble in the salt phase and concentrate there. After cooling, the salt cake can be physically separated from the metal product and discarded. 

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