Method of processing fluorination cinder

FIELD: physics, atomic power.

SUBSTANCE: invention relates to methods of processing uranium-containing solutions obtained from dissolving fluorination cinder when producing uranium hexafluoride. The method includes dissolving cinder in nitric acid solution, extracting uranium from the fluorine-containing nitric acid solution via reduction thereof with hydrazine on a platinum catalyst, with constant removal of uranium tetrafluoride precipitate from the catalyst surface, separating the catalyst from the nitric acid solution and the uranium tetrafluoride precipitate, providing an equimolar radio of fluoride ions to uranium (IV) in the obtained solution and separating the uranium tetrafluoride precipitate from the nitric acid solution, wherein the nitric acid solution is reused to resolve fluorination cinder with preliminary fortification with nitric acid.

EFFECT: invention provides a high degree of reducing uranium and reduces the amount of nitrate- and fluorine-containing wastes.

3 cl, 2 dwg

 

The invention relates to a method of refining uranium-fluorine-containing solutions obtained from dissolution Ogarkov fluoridation in the production of uranium hexafluoride.

Processing Ogarkov fluoridation containing oxychoride uranium and fluoride impurity elements, aims at the regeneration of uranium, which can be carried out, for example, by dissolving Ogarkov fluoridation in nitric acid and subsequent processing of uranium-fluorine speed by separating its uranium deposition, or extraction.

A method of refining uranium-fluorine turnovers extraction-precipitation scheme with pre-concentrated uranium by precipitation in the form of polyuranates sodium or ammonium [Tinin centuries, Balakhonov Century, Dorda F. A., Lazarchuk centuries, Ledovskikh A. K., matyukha C. A., Portnyagin E. O. Processing of uranium-fluorine-containing sublimation speed of production. Innovation in the nuclear industry: problems and solutions: Materials of scientific-practical conference of students, postgraduates and young scientists 27-30 November 2006, , Seversk: Ed. SGT, 2006, S. 24]. The disadvantage of this method is that the fluorine-containing mother liquor cannot be reused by dissolving the uranium-fluorine momentum due aciclovi fluorine.

There is a method of recovery of uranium (VI) with hydrazine nitrate solutions using latinovich catalysts [B. C. Turowski, Century, Balakhonov, Y. C. Boer, C. A. Matyukha. Influence of method of preparation of platinum catalysts on ionite media on the efficiency of recovery of uranium (VI) with hydrazine nitrate solutions // Bulletin of the Tomsk Polytechnic University. 2010. So 316. No. 3, S. 39-43]. This method includes the introduction in the nitric acid solution of uranyl nitrate containing hydrazine, platinum catalyst. The catalyst provides for the recovery of uranium (VI) with hydrazine nitrate solutions to the tetravalent state. As a carrier of platinum used anion-exchange resin. The optimum content of platinum is 4-6 wt.%. This method allows for 2 hours in a solution of nitric acid at 42-60% to recover the uranium (VI) with hydrazine on the platinum catalyst.

The disadvantages of the method:

- low degree of recovery of uranium (VI);

when the fluorine-containing processing solutions, the catalyst loses its catalytic activity, because its surface is closed from solution by precipitation.

There is a method of processing highly enriched uranium [RF patent №2112744, IPC C01G 43/00, publ. 10.06.1998] (prototype), in which the stubs fluoridation is dissolved in a solution of nitric acid, uranium is extracted by the extraction and after denitration of uranyl nitrate obtained octaoxide truran return on fluoridation. In the refined about the sought fluoride and nitrate ions.

The disadvantages of the method:

- multistage;

- large volume of liquid radioactive waste generated during the processing of fluoride and nitrosoureas refined. Neutralization of refined lime slurry [Harrington H, Ruelle A. production Technology of uranium. - M.: gosatomizdat, 1961, S. 184] with the separation of the neutral slurry of solid particles of calcium fluoride and the clear liquor into the open drainage system leads to the pollution of waters by nitrates.

The objective of the invention is to reduce the number of nitrate-containing fluorine waste generated during reprocessing uranium-fluorine-containing solutions obtained from dissolution Ogarkov fluoridation in the production of uranium hexafluoride.

The set task is solved by the fact that in the method of processing Ogarkov fluoridation, including the dissolution of Ogarkov in the nitric acid solution, the extraction of uranium from nitric acid solution, the uranium restore hydrazine in the fluorinated nitric acid solution on a platinum catalyst at a constant cleaning of the surface of the catalyst precipitation of uranium tetrafluoride. The catalyst is separated from the nitric acid solution and the precipitate of uranium tetrafluoride. Provide at least equimolar ratio of fluoride ions to uranium (IV) in the resulting solution, separate the precipitate of uranium tetrafluoride and the nitric acid solution, which, after elodokere by nitric acid re-used for dissolving Ogarkov fluoridation. Cleaning the surface of the catalyst precipitation of the uranium tetrafluoride is carried out by mechanical mixing with a catalyst or transmission ornitologijas nitrate solution through the catalyst bed in the catalytic column.

In Fig.1 presents the dependence of the growth in the number of sediment tetrafluoride uranium as the duration of the recovery process; Fig.2 - changes in the concentration of uranium (VI) in solution in the recovery process.

The method is as follows.

Spent catalytic reduction of uranium (VI) with hydrazine on the platinum catalyst (6% Pt on anion-exchange resin A-100 particle size of 0.25-0.50 mm) in nitric acid solution obtained from dissolution Ogarkov fluoridation containing U(VI) - 0.25 mol/l HNO3to 2.0 mol/l, HF - 1.5 mol/l and N2H4- 1.0 mol/l Recovery was conducted at 60°C. the Volume ratio of the catalyst to the solution was 1:10. In the process of recovering the catalyst is mechanically mixed with a solution. After two hours the solution with the precipitate and the catalyst was moved to the strainer. After filtering the grid remained the catalyst, and the nitric acid solution to precipitate the uranium tetrafluoride (in the form of double salts with hydroinform) left in the filtrate. The precipitate of uranium tetrafluoride and the nitric acid solution was separated by filtration. Isotonik the second solution is returned to the dissolution Ogarkov fluoridation, pre darkrai him on the concentration of nitric acid, closing its loss due to the formation of nitrogen oxides in the process of dissolution Ogarkov fluoridation.

It should be noted that the recovery of uranium (VI) in solutions of HF was accompanied by the growth of the precipitate of uranium tetrafluoride (see Fig.1), and the appearance in the sludge solution did not reduce the catalytic activity of the catalyst. Preservation of catalytic activity of the catalyst was ensured effective cleaning of its surface from the precipitate by mixing the catalyst solution (in additional experiments it was found that the catalyst surface is cleared of sediment UF4and the flow of the solution, if the recovery of uranium is carried out in a catalytic column by passing the solution through a layer of catalyst).

It is evident from Fig.2 shows that the content of uranium (VI) in solution during the first hour decreased from 62,9 g/l to 6.2 g/l, i.e. the degree of recovery of uranium (VI) to tetravalent state was 90.1%; after two hours the content of uranium (VI) in the solution was equal to 2.2 g/l is the degree of recovery of 96.5%. For comparison conducted the recovery of uranium (VI) under the same conditions, but used the nitric acid solution of uranyl nitrate without fluoride ions. The result, shown in Fig.2 shows that the recovery of uranium (VI) in the absence of fluoride ionospheric a much lower rate: two hours recovered 42.2% of uranium (VI).

The results presented in Fig.2, allow us to conclude that the presence of fluoride ions can be almost fully recovered uranium (VI) and put it in the precipitate of uranium tetrafluoride. In the case of fluoride ions in the solution obtained from dissolution Ogarkov fluoridation is not sufficient for full recovery of uranium (VI) in the solution after separation from the catalyst is further added fluoride ions, at least equimolar with respect to uranium (IV) number.

Thus, the catalytic reduction of uranium by hydrazine in the fluorinated nitric acid solution provides a high degree of recovery of uranium (VI) and its transfer in the precipitate of uranium tetrafluoride and allows you to reuse the filtered nitrate solution by dissolving operation Ogarkov fluoridation, thereby reducing the amount of nitrate-containing fluorine waste.

1. A method of processing Ogarkov fluoridation, including the dissolution of Ogarkov in the nitric acid solution, the extraction of uranium from the fluorinated nitric acid solution, characterized in that the uranium restore hydrazine in the fluorinated nitric acid solution on a platinum catalyst at a constant cleaning of the surface of the catalyst precipitation of the uranium tetrafluoride, the catalyst is separated from the nitric acid solution and the precipitate of tetr the fluoride of uranium, provide at least equimolar ratio of fluoride ions to uranium (IV) in the resulting solution, separate the precipitate of uranium tetrafluoride and the nitric acid solution, which, after its doreplace by nitric acid re-used for dissolving Ogarkov fluoridation.

2. The method according to p. 1, characterized in that the cleaning of the surface of the catalyst precipitation of the uranium tetrafluoride is carried out by mechanical mixing with a catalyst.

3. The method according to p. 1, characterized in that the cleaning of the surface of the catalyst precipitation of the uranium tetrafluoride is carried out by passing ornitologijas nitrate solution through the catalyst bed in the catalytic colon.



 

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1 tbl

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1 tbl, 1 ex

FIELD: chemistry.

SUBSTANCE: invention relates to chemical engineering of inorganic substances and can be used to process depleted uranium hexafluoride. The method of processing uranium hexafluoride involves dissolving uranium hexafluoride in water to obtain a uranyl fluoride solution; the obtained solution is treated with ammonia water to obtain solid ammonium polyuranate and ammonium fluoride solution; the solid fraction is filtered out and annealed at temperature of 450-600°C to thiuram octaoxide and after filtration, the solution is evaporated to obtain solid ammonium fluoride.

EFFECT: invention provides an efficient industrial method of processing uranium hexafluoride to obtain commercial-grade versions of uranium and a fluorine-containing product.

2 ex

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