GB806855A - Improvements in or relating to the production of uranium tetrafluoride - Google Patents

Abstract

A vaporous mixture of uranium hexafluoride and carbon tetrachloride comprising 2-4.5 mols. of carbon tetrachloride per mol. of uranium hexafluoride is heated at 150-400 DEG C. to produce uranium tetrafluoride. In the preferred procedure, streams of the reactants are separately preheated to at least 150 DEG C. and passed through concentric tubes into one end of an inclined rotary tube of nickel-lined stainless steel heated by a furnace where they are mixed rapidly with the assistance of a deflector plate, and pass down the tube which is maintained at 285-310 DEG C. over most of its length. The resultant solid progresses toward the lower end of the tube into a settling chamber from which it is periodically removed and blown with dry air at 300 DEG C. to remove adsorbed vapours. The vapours leaving the settling chamber have fine particles of tetrafluoride removed and are then cooled to 20 DEG C. to condense out excess carbon tetrachloride and then scrubbed with caustic soda to remove chlorine. The remaining vapours comprising fluoro-chloro-methanes are recovered by adsorption on charcoal and condensation at -20 DEG C. followed by fractional distillation. The invention is stated to have particular application to the conversion to UF4 of UF6 enriched with respect to U235. The Provisional Specification is not restricted to the above-mentioned proportions and mentions relative flow rates of 2-7.5 mols. of carbon tetrachloride to one of uranium hexafluoride; it is also stated that unless adequate residence time is provided in the tube, fluorides of intermediate composition tend to be formed. Specification 801,382 is referred to.ALSO:Vapours consisting mainly of CCl3F and CCl2F2 with small amounts of CCIF3 are obtained after separation of dust, chlorine and carbon tetrachloride, in a process wherein a vaporous mixture of uranium tetrafluoride and carbon tetrachloride having a molar ratio of 1 : 2 to 1 : 4.5 is subjected to a temperature of 150-400 DEG C. The fluorocarbons may be recovered partly by adsorption on charcoal and partly by condensation at -20 DEG C. followed by fractional distillation. Specification 801,382, [Group III], is referred to.