| 摘要 |
<p>Uranium and plutonium values are recovered from metal fluoride salt mixtures containing them by heating the salt mixture to a molten state, dispersing the mixture into droplets and contacting it with fluorine gas to convert the uranium and plutonium values to the volatile hexafluoride state, the salt droplets being contacted with fluorine at a temperature at least as great as the liquidus temperature of the salt mixture (the temperature at which all trace of solids disappears) and the volatile hexafluoride product being recovered. Metal fluoride salt mixtures specified are NaF-LiF, LiF-BeF2, NaF-ZrF4, NaF-LiF-ZrF4, KF-ZrF4 and Li7F-BeF2-ZrF4. With a mixture of composition 48.75-48.75-2.5 NaF-ZrF4-UF4 (mole per cent) the salt droplets are contacted with gaseous fluorine at between 510 DEG and 700 DEG C. The molten droplets and fluorine gas are preferably passed in countercurrent through a tower maintained at the liquidus temperature of the salt mixture, the solidified salt droplets after reaction, preferably being collected in a chilled (0 DEG C. or less) pool of fluorocarbon compound, e.g. perfluoro-1,3-dimethylcyclohexane. Helium may be introduced in countercurrent to the fluorine in the tower to serve as a blanket gas. The salt droplets are preferably of 100-200 microns particle size. The salt mixture may be sprayed down the tower or may be passed through a sieve plate to provide droplets of the required size. Alternatively a solid salt mixture may be crushed to a required particle size before being introduced into a heated fluorinator column.</p> |
