Decomposition of uranyl nitrate

Removal of Residual Nitrate From UO Uranium trioxide produced by thermal decomposition of uranyl nitrate solution in a fluidized-bed contains a small amount (usually about 0.4 to 1.0 wt%) of residual nitrate. If UO is to be converted to UF for feed to a gaseous diffusion enrichment plant, the nitrate content of the UO must be reduced to meet UF purity specifications. Fluorination of UO in the presence of nitrate results in formation of nitrosyl and nitryl hexafluorouranates and heptafluorou-ranates (NO UF where x = 1 or 2 and y = 6 or 7) (2). These compounds form potentially troublesome solids. 

Thermal Decomposition of Uranyl Nitrate Followed by Reduction in H2 at 1000°C Properties Structure confirmed by XRD, BET specific surface area 5.3 m7g [2144],... 

The lower fluorides of the actinide elements are prepared by reaction with hydrogen fluoride, either in aqueous solution or at elevated temperatures in the dry way. The latter is the more usual procedure. The methods used for the preparation of UF4 are typical of those used for the preparation of the lower fluorides of any of the actinide elements. The usual starting material for the preparation of uranium tetrafluoride is the trioxide, U03, obtained by thermal decomposition of uranyl nitrate hexahydrate, U02(N03)2 6H20. The trioxide is reduced by hydrogen to uranium dioxide, which is in turn hydrofluorinated to UF4 ... 

For the other actinide elements the usual starting material will be the dioxide. Although these reactions appear to be simple, they are in fact quite complex. Uranium trioxide as prepared by thermal decomposition of uranyl nitrate hexahydrate, uranium peroxide, or ammonium diuranate may exist in any one of at least four crystal modifications and in an important amorphous form. The reduction of U03 appears to be related both to the crystal form and to the surface area, and depending on these and perhaps other still unspecified variables, the hydrofluorination reaction on the... 

Production of Uranium Oxides by Decomposition of Uranyl Nitrate (U02(N03)2) Aqueous Solutions. Based on data presented in Section 7.6.4, calculate the energy cost of production of uranium from uranyl nitrate in the plasma-chemical process (7-102). Compare the result with the energy cost of uranium production by direct plasma dissociation of uranium hexafluoride (see Section 7.4.2). 

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],... 

Peruranates of the alkali metals are obtained by acting on alkaline solutions of uranyl nitrate with hydrogen peroxide. They are soluble in water, but may be precipitated by the addition of alcohol. Corresponding peruranates of the heavier metals may be obtained by double decomposition with solutions of the sodium salt. 

It may be prepared by dissolving any of the oxides or hydroxides of uranium in nitric acid and concentrating the solution or by double decomposition of uranyl chloride with silver nitrate. It crystallises in lemon-yellow prisms, the form of which varies according to the nature of the solvent. The crystals exhibit a yellowish-green fluorescence which does not increase, as is usually the case with phosphorescent substances, even at such a low temperature as —190° C. They also... 

Uranyl pyrophosphate, (U03)2P207, is formed as a precipitate when a solution of sodium metaphosphate is poured into a hot solution of uranyl nitrate. The tetrahydrate, (U02)2P20,.4H20, is precipitated in yellow microcrystals by double decomposition of sodium pyrophosjihate and uranyl nitrate. The hydrate loses water and yields the anhydrous salt at 120° C. Uranyl pyrojohosphate is insoluble in water, alcohol, or ether but it dissolves in excess of sodium pyrophosphate solution (see below), and also in dilute nitric acid. 

J. Formanek obtained silver uranyl chromate as a vermilion precipitate by treating a soln. of uranyl chromate with silver nitrate. Unlike J. Formanek, B. Szilard was unable to detect any decomposition of silver uranyl chromate in light even after several days exposure. J. Formanek prepared mercurous uranyl chromate in a similar manner so also lead uranyl chromate and hismuth uranyl chromate. 

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