Uranyl nitrate dehydrate

Burner designed to introduce reactants into the combustion zone. Be careful to ensure that the system is not operating within the estplosive limits. Examples include the fluorination of UF4 to UF4 at 350-600 °C with solids feed at rate of 1 Mg/d uranyl nitrate dehydrated and denitrified to uranium dioxide at rate of 1 Mg/d. Air oxidation of phosphorous to P2O5 at 2500 °C at 1.5 Mg/h. This reactor is 1.8 m diameter, 10 m high with gas flow of 1 m/s and molten flow of 0.4 kg/s. 

In TBP extraction, the yeUowcake is dissolved ia nitric acid and extracted with tributyl phosphate ia a kerosene or hexane diluent. The uranyl ion forms the mixed complex U02(N02)2(TBP)2 which is extracted iato the diluent. The purified uranium is then back-extracted iato nitric acid or water, and concentrated. The uranyl nitrate solution is evaporated to uranyl nitrate hexahydrate [13520-83-7], U02(N02)2 6H20. The uranyl nitrate hexahydrate is dehydrated and denitrated duting a pyrolysis step to form uranium trioxide [1344-58-7], UO, as shown ia equation 10. The pyrolysis is most often carried out ia either a batch reactor (Fig. 2) or a fluidized-bed denitrator (Fig. 3). The UO is reduced with hydrogen to uranium dioxide [1344-57-6], UO2 (eq. 11), and converted to uranium tetrafluoride [10049-14-6], UF, with HF at elevated temperatures (eq. 12). The UF can be either reduced to uranium metal or fluotinated to uranium hexafluoride [7783-81-5], UF, for isotope enrichment. The chemistry and operating conditions of the TBP refining process, and conversion to UO, UO2, and ultimately UF have been discussed ia detail (40). 

There have been many instances of examination of the effect of additive product on the initiation of nucleation and growth processes. In early work on the dehydration of crystalline hydrates, reaction was initiated on all surfaces by rubbing with the anhydrous material [400]. An interesting application of the opposite effect was used by Franklin and Flanagan [62] to inhibit reaction at selected crystal faces of uranyl nitrate hexa-hydrate by coating with an impermeable material. In other reactions, the product does not so readily interact with reactant surfaces, e.g. nickel metal (having oxidized boundaries) does not detectably catalyze the decomposition of nickel formate [222],... 

When uranyl nitrate hexahydrate is placed in an enclosed space with sulphuric acid at ordinary temperature and pressure it undergoes dehydration in two stages, yielding after a few days the trihydrate,... 

Heat capacity of uranyl sulfate solutions. Van Winkle [57] estimated the heat capacity of dehydrated uranyl sulfate by comparison with uranyl nitrate and with salts of other metals and has estimated the heat capacity of solutions of uranyl sulfate in heavy water and in light water. The effect of temperature on the heat capacity of solutions was assumed to be the same, percentagewise, as the effect on the heat capacity of the pure solvent. Table 3-10 shows the influence of uranyl sulfate concentration upon the heat capacity of solutions at 25 and 250°C. No experimental measurements have been reported for temperatures above 103°C values below this temperature differ from the estimates by as much as 10% [57],... 

The standard molar Gibbs energy of reaction (8.12) on the mole fraction scale when dodecane is the diluent of the TBP is AG° = -46 kJ mol", the reaction being dominated by its enthalpy change, AH° = -55 kJ mof as determined by Marcus [30]. The net enthalpy change arises from the amount invested in desolvation (dehydration) of the uranyl ion (aq) and the two nitrate ions N03 (aq) but regained... 

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