METHOD FOR CRYSTALLIZATION SEPARATION AND PURIFICATION OF URANYL NITRATE HEXAHYDRATE AND DEVICE FOR ITS IMPLEMENTATION Russian patent published in 2021 - IPC G21C19/00 

FIELD: crystallization technologies.

SUBSTANCE: group of inventions relates to heat and mass transfer processes in systems with liquid and solid phases, namely, to a method for crystallization separation and purification of uranyl nitrate hexahydrate, which includes the crystallization of uranyl nitrate hexahydrate from a concentrated nitric acid solution of uranyl nitrate, a feed stream with a composition corresponding to the ratio [UN]=78.49 - k[HNO₃], where [UN] and [HNO₃] are the concentrations of uranyl nitrate and nitric acid, wt. % ; where 78.49 is the concentration of uranyl nitrate in the crystalline uranyl nitrate hexahydrate, wt. %; k - the coefficient determining the position of the working line of the crystallization process and having a numerical value from 1.50 to 2.24, preferably from 1.57 to 1.80, separation of crystals of uranyl nitrate hexahydrate and the mother solution, countercurrent washing of crystals, collection of crystals of uranyl nitrate hexahydrate into a collection tank with simultaneous displacement of the washing solution from the tank into the washing zone and unloading of the purified product, and crystallization of uranyl nitrate hexahydrate from the feed stream, washing and collection of crystals it is carried out under isothermal conditions, while the initial, including the non-uranium composition of the washing solution meets the condition of the family of working lines 78.49=k₁[HNO₃], where [HNO₃] is the content of nitric acid in the washing solution, wt. % and k₁≤k, where k₁ is the coefficient determining the position of the working line of the washing process, the mother solution and the spent washing solution are sent in a single stream to additional crystallization carried out at a temperature below the crystallization temperature with countercurrent movement of the liquid and solid phases, the crystals of uranyl nitrate hexahydrate of additional crystallization are washed together with the crystals obtained from the feed stream, and the mother solution of additional crystallization is removed from the process. In addition, a device for crystallization separation and purification of uranyl nitrate hexahydrate is described, containing an additional mold with a paddle agitator and a thermostatic case mounted on the outlet of the mother and washing solutions, while the axis of the additional mold is parallel to the axis of the mold.

EFFECT: simplifying the technological process by achieving high and independent indicators for the operational yield and purification of the product, which can be used in hydrometallurgical technologies of the nuclear fuel cycle at the stages of refining natural or regenerated uranium.

4 cl, 3 dwg, 1 tbl