GB884666A - Improved process for the preparation of uranium tetrafluoride from uranium dioxide - Google Patents

Abstract

In the preparation of UF4 from UO2 by hydrofluorination, the UO2 is first slightly oxidized, preferably to give an increase in hexavalent uranium of at least 1%, and more preferably at least 2%. The UO2 may be obtained by the reduction of UO3 with hydrogen, preferably at 1000 DEG -1150 DEG F., and the UO3 may in turn have been obtained by calcining uranyl nitrate hexahydrate. The hydrofluorination may be effected at 550 DEG F. to 1000 DEG F., preferably in a fluidized bed, although vibrating tray or screw reactors may also be employed. The oxidation of the UO2 may be effected in a fluidized bed reactor, preferably connected directly to the reduction reactor. An oxygen containing gas, preferably nitrogen containing 2-4% oxygen is employed, and the temperature is preferably about 400 DEG F. The slightly oxidized UO2 passes into the hydrofluorination reactor. The UF4 product may either be recovered as such or contacted with fluorine to give uranium hexafluoride. The process may be combined with known means of improving the UO2 reactivity, such as employing UO2 which has been obtained from UO3 prepared by batchwise calcination of uranyl nitrate hexahydrate in pots, or by controlled hydration and dehydration of the UO3 from which the UO2 is obtained, or by the addition of sulphate ions.