Purification of uranium tetrafluoride using ammonium bifluoride

• A method of purification of UF4 using a solid-solid reaction with NH4HF2 was found to effectively remove suspected oxygen and hydrate impurities from the salt. • The method is both inexpensive and avoids the hazards of working with HF gas. • The method will be at least extremely useful for purifying laboratory quantities of UF4 • Purification method validated using inert gas fusion, differential scanning calorimetry, x-ray diffraction, and inductively coupled plasma optical emission spectrometry. A method of purification for UF 4 utilizing NH 4 HF 2 was investigated to remove oxygen and hydrate impurities from the salt. The original salt exhibited a melting point at 915-920 °C, which corresponds to the eutectic temperature of the UF 4 -UO 2 system, showing clear signs of oxygen contamination. To purify the salt, an air-tight reaction vessel inside an argon glovebox was used to react UF 4 /NH 4 HF 2 mixtures at elevated temperatures under a continuous flow of inert gas. The process yielded a significantly purer UF 4 salt as confirmed via inert gas fusion, X-ray diffraction, differential scanning calorimetry and inductively coupled plasma-optical emission spectrometry.