Thermodynamic analysis and experimental study on the chlorination of uranium oxide by gas-solid reaction

In order to determine the operating condition of an uranium chlorination process with U₃O₈-C-Cl₂ system, the experimental conditions have been evaluated preliminarily by the thermochemical analysis and experimentally confirmed in this study. The dry-type chlorination of U₃O₈ occurs as irreversible and exothermic reaction and produces many kinds of chloride compounds such as UCl₃, UCl₄, UCl₅ and UCl₆ in the air and humidity controlled argon environment. Taking account of Gibbs free energy and vapor pressure for various chloride compounds, the proper temperature range of chlorination appears to be 863 to 953 K in aspects of increasing reaction rate and the yield of nonvolatile product. In the course of the experimental confirmation the powder of U₃O₈ is perfectly converted into uranium chlorides within 4 hours above 863K, and then the maximum fraction of uranium chloride remaining in the reactor is about 30% of total conversion mass.