DE2927212A1 - METHOD FOR ISOTOPE SEPARATION - Google Patents

Description

Process for isotope separation

The invention relates to a method for chromatographic Isotope separation, with a platform (at isotope equilibrium with the originally supplied solution) inside of the chromatogram is maintained, thereby producing an enriched isotope with increased efficiency becomes possible.

According to the method of the invention, all processes are to be simplified, the efficiency of the overall separation in the method Liquid or gas chromatography to generate enriched isotopes can be improved.

This is achieved, surprisingly, in that the isotope platform is maintained by adding a very wide one in the column Absorption band is formed in which the enriched and depleted zones, which are formed at the head part and the tail part of the chromatogram, always remain separated from each other.

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The method according to the invention makes it possible, for example, lithium-6 from lithium-7, boron-10 from boron-11 and also to separate other isotopes such as uranium-235 from uranium-238.

The chromatographic methods of the invention for producing enriched isotopes include the following two steps:

a) previous enrichment stage (start up)

b) Production stage.

The previous enrichment stage is that at which the chromatographic device is started and runs without withdrawing any product stream until the atomic fraction of the expected isotopes meets the required Has reached the value at the head or tail of the chromatogram.

In the subsequent production stage, a product of the desired atomic fraction is semi-continuous or continuously subtracted from the head or tail of the chromatogram.

The separation efficiency of the chromatographic isotopic separation according to the prior art is shown in FIG Tendency to deteriorate as the enriched and depleted zones overlap and mix an isotope lead.

According to the method of the invention, the chromatography is carried out in such a way that the shift fronts at the head and / or are formed at the tail of the chromatogram and that the sum of the concentrations of the two isotope species remains constant.

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The chromatographic band is wide enough that the always keep enriched and impoverished areas separate from each other; no overlap between them occurs.

The process can be broken down into its main features describe as follows: -

a) Prevention of isotope mixing during a platform (in isotope equilibrium with the supplied Solution) between the enriched and the impoverished Area is maintained;

b) Preventing a broadening of the enriched and impoverished areas, as evidenced by changes in the Total concentration evoked;

c) the central area of the chromatogram can be filled with additional Quantities of feed solution can be fed without interrupting the process.

The result is improved production of the expected enriched isotopes to be seen.

Exemplary embodiments of the invention are now intended described on the basis of chromatography in the liquid phase will. - ".

Example 1 - Preparation of Lithium-6

Lithium occurring in nature consists of two isotopes, namely lithium-6 (7.2%) and lithium-7 (92.81).

A column arrangement according to FIG. 1 (each column has a diameter of 22 mm and a length of 1300 mm) was filled with an ion exchange resin Dowex 50 W up to a height of 1200 mm; the resin was in acid form R-H converted. An absorption band was formed by the column arrangement with a 0.3 M aqueous solution on lithium acetate, CH, CoOLi was fed; a chromato-

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The graphical run was then set up by eluting the absorbance band with a 0.3 M aqueous solution of sodium acetate, CH ₃ COONa.

This made it possible to enrich the head part of the absorption band with lithium-7 and the tail part with lithium-6.

I. While maintaining an isotope platform :

A lithium absorption band 6 meters wide was formed and pushed through the columns. After hike Over a total distance of 202 meters, the atomic fraction of lithium-6 at the tail end of the tape was from 7.2 to 15.01 elevated.

It has thus become possible to use 151 enriched lithium-6

2 at a rate of 2.9 millimoles per cm per day by adding naturally occurring lithium to the middle leg of the chromatogram. At the top portion of the tape, the atomic fraction of the lithium-6 of the drawings has been reduced from 7.2% to only 2, 9% by walking over a distance of 202 meters, as shown in FIG. 2.

II. Without maintaining the isotope platform

A three meter wide lithium column was formed and shifted through the column arrangement.

To enrich the atomic fraction of lithium-6 at the head section from 1.2% to 15.0%, the tape had to be shifted over a total distance of 450 meters.

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At this point it would have lithium-6 enriched by 15%

"2 at a speed of 1.4 millimoles per cm and Tag can be generated.

However, it became difficult to deliver a fresh feed solution to the center of the band without closing the chromatogram so that the rate of production dropped as shown in Fig. 3.

Example 2 - Production of Boron-10

Naturally occurring boron consists of two isotopes, namely Bör-10, (19.8%) and Bor-11 (80.2%).

A column according to FIG. 4 of the drawings with a diameter of 22 mm and a height of 4100 mm was treated with an anion exchange resin (anionic exchange resin), which was weakly basic, _ Diaion WA 21, filled in the form of a free base up to a height of 4000 mm, the resin was converted to the basic form R-OH and washed with pure water.

The column was then filled with an aqueous boric acid solution applied to form an absorption band; chromatography was performed by eluting the band with Water carried out.

This made it possible to use boron-11 and to enrich the tail part with boron-10.

I. While maintaining an isotope platform

A 4 meter ionic exchange column was first equilibrated with 5.0 liters of a 0.1 M aqueous solution of boric acid.

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The front part of the absorption tape was thrown off so that the enriched boron-11 was not recovered.

Chromatography was performed using the absorbance band was eluted with water and boron-10 was enriched from 19.81 to 33.3% at the tail end of the tape. The width of the enriched zone was 34 cm as shown in Figure 5 of the drawings.

II. Without maintaining an isot open platform

After the column was initially charged with 2.0 liters of a 0.1 M solution of boric acid, it showed impossible to perform any displacement chromatography or an isotope platform inside the To maintain the chromatogram.

After migrating a distance of 4 meters, the atomic fraction of boron-10 only reached the tail end of the tape 25.81 and the width of the enriched zone was 96 cm as shown in Figure 6 of the drawings.

Example 3 - Preparation of 901 Boron-10

The production of boron-10 with a value up to 901 was made by the same procedure as described in Example 2 carried out.

A group of columns as shown in Figure 7 of the drawings, each 21 mm in diameter and a length of 1100 mm, was filled with resin up to a height of 1000 mm, the resin was first processed, as described in Example 2. Each column was first equilibrated with 2.0 liters of a 0.1 M boric acid solution

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Each column was treated with an excess of the solution, so that the boron-10 depleted zones were thrown away, whereby the resin is in both chemical and isotopic equilibrium was left with the fed solution.

The columns were then connected via "internal diameter vinyl chloride" tubing of 0.8 mm connected in series; Chromatography was performed by adding water to the first column of the group was given and the boric acid through the remaining Columns was moved. The width of the absorption band was kept very wide, so that a platform (in the Isotopegled weight with incoming solution) during the whole Operation was maintained.

After complete elution of the boric acid from the first column, the column was withdrawn from the column assembly and re-equilibrated with the feed solution and connected in currents ^r flow direction at the other end of the group.

Through this l'i-eß-. the absorption band is slightly along a long distance without interrupting the process. After the tape had hiked the total distance of 250 meters, the atomic fraction of boron-10 was at the tail end of the band enriched on 901; 901 enriched boron-10 was produced at a rate of 0.09 millimoles per cm per day as shown in FIG.

As these examples clearly show, can be enriched Produce isotopes more efficiently when an isotope platform Maintained inside the separation chromatogram will. -

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Fig. 1 shows schematically the arrangement of the column group for the production of lithium-6.

The reference number 1 stands for a solution of lithium acetate, which is used to form the lithium absorption band. Reference number 2 stands for a solution of eluting sodium acetate, whereas 3 indicates an acetic acid solution as it is used for regenerating the resin. The dashed one Part of the columns shows the lithium absorption band. The dotted part indicates the resin that is in the sodium form R-Na at 5 or in the acidic form R-H at 6 was eluted.

Figure 2 shows the chromatogram of the lithium maintained the isotope platform with a length of 6 meters, made as a result of the migration of the Absorption band over a length of 202 meters.

The elution curve 1 shows the concentration of lithium, expressed in moles per liter and plotted on the ordinate Axis on the left as a function of the position in the chromatogram, expressed in meters and plotted on the abscissa axis.

The application of the atomic fraction (ratio of the number of atoms of an isotope present in the element to the number of Total atoms) ^, gives the percentage of the atomic fraction of lithium-6, plotted on the ordinate axes on the left as a function of the position in the chromatogram in meters, which is plotted on the left on the abscissa axis.

The dashed line 3 indicates the original atomic fraction of lithium-6, which is 7.21.

FIG. 3 shows a chromatogram similar to FIG. 2, but without maintaining the isotope platform; the reference numerals are the same as in Fig. 2;

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ORtGINALINSPECTED

Fig. 4 shows a single column for enrichment of boron-10. 1 is the one used for absorption Boric acid; 2 elution water.

The hatched part 3 of the column gives the boron absorption band at. _

With the dotted part 4 is the already eluted resin designated.

Fig. 5 shows the chromatogram of the boron maintained the isotope platform in agreement with the original atomic fraction of boron-10, which is 19.8%.

The elution curve 1 gives the concentration of boric acid, expressed in moles per liter and plotted on the axis the ordinate on the left as a function of the position on the chromatogram, which is expressed in meters and on the abscissa axis is applied.

Fig. 6 shows a chromatogram similar to that of Fig. 5, but without maintaining the isotope platform; the symbols are the same as in Fig.

Fig. 7 shows schematically the arrangement of a group of Columns for the production of boric acid enriched with boron-10, the reference numerals the same as in Flg. 4 are; and

Fig. 8 shows the chromatogram of the boron while maintaining the isotope platform in the case of the production of the 90ligen Bor-10, the symbols are the same as in Fig. 5.

0 30 0 07 /0.6a a

A chromatogram length of 250 meters corresponds at the tail end of the tape to the tape with 90% enriched boron-10.

With regard to a concise presentation, the invention is explained using only a few examples; Changes and amendments are within the scope of the invention.

A method for separating isotopes has thus been described, in which an isotope platform is provided in a chromatographic column or an isotopic platform is maintained by forming a very wide absorption band to make it sharp to separate the enriched zones from the depleted ones at the head and tail of the chromatogram: the column does not produce any Product removed until the atomic fraction of the isotope sought has reached the desired enrichment value.

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Claims (4)

Isotope Separation Process PATENT CLAIMS 1. Method for isotope separation by liquid or gas chromatography, with a platform in isotope equilibrium with the original injected solution is inside the chromatogram, creating a more effective one Production of the desired enriched isotopes is possible, characterized in that the Isotopepiattform is maintained by a very broad absorption band is formed in the column, in which the accumulated at the head and tail of the chromatogram and impoverished areas are always separated from each other being held. 2. A method for isotope separation according to claim 1, -._- " thereby g e k e η η ζ e i c h η e t that the platform in isotopic equilibrium with the original fed solution to prevent mutual mixing of isotopes, a broadening of the enriched and depleted zones and that the central part of the chromatogram with additional amounts of feed solution is supplied without interruption of the proceedings. 3. The method according to any one of the preceding claims, characterized in that after the previous start-up phase in which a platform is maintained will, without deducting any product, until the atomic fraction of the expected isotope the required enrichment value at the head or tail of the chromatogram, followed by an actual production stage, in which the product is semi-continuous with the desired atomic fraction or continuously subtracted from the head or tail of the chromatogram. ORIGINAL INSPECTED 4. Application of the method for isotope separation according to one of the preceding claims to the exemplified Isotopic lithium-6 and boron-ΙΟ as well as other isotopes, in particular Uranium-235. 030007/0699