JPH0571285B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for enriching boron isotopes. More specifically, by forming a boric acid adsorption zone on the aminopolyol type anion exchange resin layer under specific conditions and moving the adsorption zone under specific conditions, boron isotopes are produced in the form of boric acid. It relates to a method of concentration. Boron is widely distributed in nature, Boron 10 (10B)
It consists of two stable isotopes of boron 11 (11B) and
Approximately 20% of 10B and 80% of 11B exist in nature. Among these, 10B has excellent properties as an absorber for neutrons generated by nuclear reactions, and is used as a neutron absorbing material such as chemical shims for pressurized water reactors, control rod materials for boiling water reactors, and fast breeder reactors. It is an essential substance in the nuclear industry. As mentioned above, the natural abundance of 10B is low at about 20%, and the rest is 11B, which has almost no neutron absorption capacity. Therefore, in order to efficiently absorb neutrons in nuclear reactors and control this, requires enriching 10B from natural boron, which is an isotopic mixture of 10B and 11B. One of the methods for enriching boron isotopes is a method using ion exchange chromatography. This method is broadly classified depending on the type of ion exchange resin used.
There are methods using strongly basic anion exchange resins, methods using weakly basic anion exchange resins, and methods using anion exchange resins having as a functional group aminopolyols that form strong complexes with boron. Among these, the resin-based method is from Bull.Chem.
Soc.Japan, vol. 50, p. 158. Then, in the dissociation equilibrium of boric acid in the external solution in contact with the ion exchange resin, more 10B is distributed to the dissociated species side, as shown in equation () below, and ¹⁰ B(OH) ₃ + ¹¹ B(OH) ^- ₄ K 10B(OH) ^- ₄ +11B(OH) ₃ () K=1.02 (20℃) The separation coefficient (α ¹⁰ ₁₁ ) of boron isotopes, which is generally expressed by equation (), is governed by this equilibrium constant. Ru.
Since the ion exchange resin used at this time only serves as an adsorption medium for boric acid, α ¹⁰ ₁₁ = (molar concentration of 10B in the ion exchange resin) / (molar concentration of 11B in the ion exchange resin) / (Molar concentration of 10B in solution) / (Molar concentration of 11B in solution) () The separation coefficient is small, and in addition, the separation coefficient in this system is highly dependent on the boric acid concentration in the external solution.
It decreases rapidly as the boric acid concentration increases, so
In this system, separating boron isotopes and concentrating 10B to a desired concentration requires a large amount of time and a large number of chemicals, and cannot be said to be an efficient separation method. On the other hand, the chelating anion exchange resin that has aminopolyols as a functional group forms a strong complex with boron and selectively adsorbs boric acid, so it is used for the adsorption and removal of boric acid from various solutions. This type of product has already been developed, such as Diaion CRB02 (manufactured and sold by Mitsubishi Chemical Industries, Ltd., product name) and Amberlite IRA-743.
(Manufactured by Rohm and Haas, USA, product name)
are commercially available, of which Amberlite IRA
A method for separating boron isotopes using -743 (Amberlite XE-243) is described in French Patent No. 1520521. This type of resin not only forms a strong complex with boron, but also has a higher separation coefficient for 10B and 11B isotopes compared to the above method using a normal anion exchange resin. The reaction rate is slow, especially the isotope exchange reaction rate of 10B and 11B, so compared to methods using normal anion exchange resins,
HETP (Height Equivalent of
Theoretical Plate) HETP=(L ₂ − L ₁ ) lag α ¹⁰ / ₁₁ / log (R ₂ / R ₁ ) (
) (However, R ₁ and R ₂ are the positions of the boron isotope enrichment zone
Because it has the disadvantage of a large isotope ratio (L ₁ to L ₂ ), it cannot be said to be efficient in separating and concentrating boron isotopes. The present invention solves the above problems in boron isotope enrichment using a chelating anion exchange resin having aminopolyols as a functional group (hereinafter referred to as aminopolyol type anion exchange resin),
The object of the present invention is to provide a method for efficiently separating boron isotopes by taking advantage of the high boron isotope separation coefficient of the resin. That is, the present invention involves flowing boric acid through a resin layer made of an aminopolyol type anion exchange resin to form a boric acid adsorption zone, and then expanding with acid to concentrate boron isotopes. , the concentration of the boric acid solution to be distributed is 0.2-2M/
range and none, and the temperature when unfolding is 40 ~
The temperature range is 100℃ and the concentration of the acid used is 0.2
The gist of the present invention is a method for enriching boron isotopes in the range of ~2M/. The aminopolyol type anion exchange resin used in the present invention is produced by first producing a crosslinked polymer having a halomethyl group, and then reacting this with a specific amine. A crosslinked polymer having a halomethyl group can be produced by, for example, dissolving a monovinyl aromatic monomer such as styrene and a polyvinyl aromatic monomer such as divinylbenzene, and then dissolving the resulting crosslinked polymer. Copolymerization is carried out by adding a swelling solvent such as benzene, toluene, xylene, chlorobenzene, carbon tetrachloride, tetrachloroethane, trichloroethylene, etc. to the monomer in an amount of about 0 to 200% by weight, resulting in a gel-like or porous product. A method of reacting a polyester copolymer with chloromethyl methyl ether, or a method of copolymerizing by adding an aromatic linear polymer such as polystyrene in an amount of about 0 to 50% by weight based on the total amount of monomers when copolymerizing the above monomers. After that, the linear polymer is extracted and removed with a solvent, and the resulting gel-like or porous copolymer is reacted with chloromethyl methyl ether.Alternatively, the above monomer is dissolved, but the produced The crosslinked copolymer is polymerized by adding a solvent (precipitating solvent) such as n-pentane, i-octane, n-heptane, etc. in an amount of 0 to 120% by weight based on the total amount of monomers, and the resulting gel-like or porous It is produced by halomethylating a copolymer using the method described above. As the monovinyl aromatic monomer used in the above method, in addition to styrene, aromatic vinyl compounds such as vinyltoluene, ethylstyrene, vinylanisole, and vinylnaphthalene are useful.
In addition to divinylbenzene, useful polyvinyl aromatic monomers include divinylethylbenzene, divinyltoluene, divinylnaphthalene, divinylxylene, divinyl ether, ethylene glycol dimethacrylate, ethylene glycol diacrylate, and divinyl ketone polyallyl ether. The amount used can vary within a wide range, but is preferably from 2 to 50% by weight, based on the total monomers. For copolymerization, a polymerization catalyst such as benzoyl peroxide, lauroyl peroxide, or azobisisobutyronitrile is added in an amount of 0.1 to 10% by weight based on the monomer.
As the polymerization method, which is carried out by reacting at a temperature of 6 to 20 hours, known methods such as suspension polymerization and bulk polymerization can be employed. Halomethylation of the aromatic crosslinked copolymer is carried out by a known method, for example, using chloromethyl methyl ether in the presence of a Friedel-Crafts catalyst such as zinc chloride and heating to 20-60°C. The amount of chloromethyl methyl ether can vary within a wide range per 100 g of aromatic crosslinked copolymer, but is preferably
A range of 80g to 500g can be mentioned. In addition to the method described above, the aromatic crosslinked polymer having a halomethyl group can be obtained by crosslinking copolymerization of a halomethylated aromatic monovinyl compound such as chloromethylstyrene and a polyvinyl compound such as divinylbenzene according to the method described above. It can also be produced by a method. The specific amine to be reacted with the crosslinked copolymer having a halomethyl group has the following general formula ()

[However, in the formula, n represents an integer of 1 to 6,
R is a hydrogen atom, _an alkyl group having 1 to 5 carbon atoms, or _-CH2 [-CH(OH)]- _nCH2OH (in the formula, m is 0,
(indicates an integer from 1 to 6)] Specifically, the above-mentioned specific amines include glucamine, galactamine, mannamine, N-methyl-glucamine, N-ethyl-glucamine, N-methyl-galactamine, N-ethyl-galactamine, N-methyl-mannamine. , N-ethyl-mannamine, and the like. Furthermore, examples of the anion exchange resin used in the present invention include aminopolyol type anion exchange resins obtained by reacting phenol with amines of the above general formula () and then condensing it with aldehydes. Since the anion exchange resin used in the present invention has an aminopolyol group as a reactive group, it exhibits what is generally called a chelating property. The anion exchange resin produced as described above is converted into a free amine form by treating the amine functional group of the resin with an alkaline solution. Examples of the drug used to form the free amine form include commonly used alkaline solutions, such as alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, and aqueous solutions such as ammonium hydroxide. The anion exchange resin used in the present invention is of the free amine type as described above, but the resin of the free amine type may also be heat-treated under specific conditions as shown below. It can also be used. That is, this heat treatment is performed using water, an alkaline solution such as sodium hydroxide, ethylene glycol,
It is carried out in a medium of (poly)alkylene glycols such as propylene glycol and polyethylene glycol, alcohol amines such as ethanolamine, diethanolamine and propanolamine, or glycerin. These media may be used alone or in a mixed state. As the heat treatment method, a method is adopted in which the free amine type resin obtained as described above is treated in the above medium at a temperature of 60°C or more and 200°C or less, preferably 100°C or more and 150°C or less. The time required for the heat treatment varies depending on the heating temperature, and for example, in a temperature range of 100° C. or higher and 150° C. or lower, 0.5 to 50 hours is appropriate. The time required for heat treatment varies depending on the heat treatment method; for example, in the so-called batch treatment method in which the resin is immersed in the above medium, the time required for heat treatment is 100°C or more and 150°C
0.5 to 20 hours is appropriate at the following temperatures; the higher the heating temperature, the shorter the time. On the other hand, in the so-called distribution method, in which the resin is packed into an ion exchange column and heated while flowing the above-mentioned medium through it, the temperature is higher than 60°C due to problems such as the heat resistance temperature of the equipment.
The appropriate time is 20 hours or more and 100 hours at a temperature of 100° C. or lower, and in this case as well, the higher the temperature, the shorter the time required for the heat treatment. It is explained that the anion exchange resin used in the present invention is a free amine form of an aminopolyol type anion exchange resin as described above, or a resin obtained by further heat-treating the free amine form under specific conditions. However, in addition, the free amine form of the resin is
Those treated with certain alkaline solutions can also be used. That is, the free amine type resin obtained above is treated with an alkaline solution containing A and B shown below. A: Alkali metal hydroxide or ammonium hydroxide B: Alkali metal salt or ammonium salt Examples of the alkali metal hydroxide include sodium hydroxide, potassium hydroxide, lithium hydroxide, etc., and examples of the alkali metal salt include , sodium chloride, potassium chloride, sodium sulfate, etc., and examples of the ammonia salt include ammonium chloride, ammonium sulfate, etc. Alkaline solutions containing A and B include sodium hydroxide and sodium chloride, potassium hydroxide and sodium sulfate, sodium hydroxide and sodium sulfate, ammonium hydroxide and sodium sulfate, ammonium hydroxide and ammonium chloride, water Examples include aqueous solutions of ammonium oxide and ammonium sulfate, but preferably an aqueous solution of ammonium hydroxide and ammonium chloride or ammonium sulfate. Further, the concentration of the mixed solution of A and B is preferably in the range of 0.5 to 10% by weight, and the mixing ratio of A and B in this mixed solution is an equivalent ratio of 1:10 to 5:1. It's fine as long as it's within the range. The boron isotope enrichment of the present invention involves passing a boric acid solution through a column filled with the anion exchange resin obtained by the above method to adsorb boric acid on the resin.
This is then carried out by so-called column chromatography in which the boric acid adsorption zone is developed with an acid solution. The boric acid concentration when forming a boric acid adsorption zone using the above anion exchange resin of the present invention is 0.2
-2.0 mol (M)/. Examples of acids used for development include hydrochloric acid and sulfuric acid. Further, the concentration of the acid used for the development may be in the range of 0.2 to 2.0M/. The operating temperature for boron isotope separation can range from 40 to 100°C. At temperatures lower than this, a sufficient isotope exchange reaction rate cannot be obtained, and the high solution viscosity increases pressure loss in the ion exchange column during separation operations. On the other hand, at temperatures higher than the above range, problems arise in the heat resistance of the resin during long-term use. The method of the present invention can achieve a high separation coefficient of boron isotopes by forming a boric acid adsorption zone and moving the adsorption zone under the above-mentioned specific conditions. The particle size of these anion exchange resins depends on the isotope exchange reaction rate in boron isotope separation, the rate of adsorption and desorption between boric acid during acid development and the acid used for development, and the ion exchange tower filled with the resin. The average particle diameter of the resin can be in the range of 50 to 300 μm within the above boric acid concentration and operating temperature range, although it is determined in consideration of pressure loss and the like. Furthermore, under the above conditions, the rate of expansion of the boric acid adsorption zone by acid using an ion exchange tower filled with the resin is determined by taking into account the isotope exchange reaction rate of the resin and the pressure loss of the ion exchange tower. If the development speed is slow, the productivity of the boron isotope separation concentrate will decrease, and if the development speed is fast, the linear velocity of the developing solution will also be high, resulting in too large a pressure drop in the ion exchange column or the ions that have been developed by the acid. Because this may interfere with the regeneration of the resin in the exchange tower, the flow rate (LV) should be 0.5 to 20 in the above boric acid concentration and operating temperature range.
A range of m/hr is desirable. Next, a method for separating and concentrating boron isotopes using an ion exchange column filled with an anion exchange resin of the present invention will be explained. Examples include a through method, a substitution expansion method, and a method using a combination of a reverse breakthrough method and a substitution expansion method. Reverse breakthrough method (Bull.Chem.Soc.,
(JPN, Vol. 53, No. 7, p. 1860) An example of the method of the present invention using the reverse breakthrough method will be explained with reference to FIG. C ₁ to C ₆ in Figure 1
is an ion exchange column filled with the anion exchange resin used in the present invention. The temperature inside the column is kept constant by heating the feed liquid and by providing a jacket in the column to circulate hot water or the like, or by providing a heat insulating material. V ₁₁ to V ₁₆ are solution switching valves for supplying liquid to the tower, V ₂₁ to V ₂₆ are solution switching valves for sorting the liquid discharged from the tower, and M ₁ to M ₆ are solution switching valves for supplying liquid to the tower. A detector for monitoring the acid adsorption zone is shown. First, each ion exchange column from C ₁ to C ₆ is regenerated with an alkaline solution such as sodium hydroxide or ammonium hydroxide, and then washed with demineralized water. After that, C ₁ to C ₆ are connected in series, and the liquid is drained from V ₂₆ . At the same time, a boric acid solution is supplied from V ₁₁ until the resin reaches equilibrium. Thereafter, the boric acid adsorbed on the resin is developed with an acid solution from V ₁₁ , and the liquid is drained from V ₂₆ . The expansion with acid continues, and when the rear end interface of the boric acid adsorption zone moves to the C ₂ tower, the acid supply is switched to V ₁₂ , and the C ₁ tower, which has become an acid adsorption type, supplies alkaline solution from V ₁₁ to V _21. Demineralized water is supplied from V ₂₁ for cleaning, and then boric acid solution is supplied from V ₁₁ and drained from V ₂₁ to provide an equilibrium amount of boric acid to the resin in the C ₁ column. Pass the liquid through. The steps of regeneration, water washing, and boric acid adsorption of the C ₁ tower are completed before the rear end interface of the boric acid adsorption zone developed with acid moves from the C ₂ tower to the C ₃ tower. When the rear end interface of the adsorption zone moves to the C ₃ tower, the acid supply is switched to V ₁₃ ,
Connect V ₂₆ to V ₁₁ , drain the solution from V ₂₁ for development of the boric acid adsorption zone, and continue development of the boric acid adsorption zone with acid. Here, the C ₂ tower is regenerated in the same way as the previous C ₁ tower,
Wash with water and absorb boric acid. By repeating this method, 10B is concentrated at the rear interface of the boric acid adsorption zone. When the 10B concentration reaches a desired concentration, for example, the 10B concentration interface is extracted from the drain valve at the bottom of the ion exchange column, thereby producing a 10B concentrate. Substitution expansion method (J.Am.Chem.Soc., vol. 77, 6125
Page) Using the same anion exchange resin and equipment as in the reverse breakthrough method described above, the method will be explained with reference to FIG. That is, the ion exchange towers from C ₁ to C ₆ are regenerated with an alkaline solution such as sodium hydroxide, washed with demineralized water, and connected in series from the C ₁ tower to the C ₃ tower.
The boric acid solution is supplied from V ₁₁ , drained from V ₂₃ , and passed through until a complete equilibrium state is reached. Next, the C ₁ column is connected to C ₅ and an acid solution is supplied from V ₁₁ to perform displacement development of the boric acid adsorption zone.
At the point where it moves from the rear end interface of the boric acid adsorption zone to the C ₂ tower, the acid supply is switched from V ₁₁ to V ₁₂ , and at the same time, the C ₆ tower is connected and the waste liquid is switched from V ₂₅ to V ₂₆ to carry out substitution development. continue. Meanwhile, the development with acid has finished.
The C ₁ column is regenerated by supplying alkaline solution from C ₁₁ and draining from V ₂₁ , and is similarly then washed with water and prepared for the next development. The regeneration and water washing operations of the C ₁ tower are completed until the rear end interface of the boric acid adsorption zone is transferred to the C ₃ tower. When the rear end interface of the boric acid adsorption zone moves to the C ₃ column, the acid supply is switched from V ₁₂ to V ₁₃ .
Next to the C ₆ column, the C ₁ column is connected, and the liquid is drained from V ₂₁ to continue the displacement development. During this time, the _C2 tower regenerated,
Wash with water. By repeating this method, 11B is concentrated at the front end interface of the boric acid adsorption zone, and 10B is concentrated at the rear end interface, and when each reaches the desired concentration,
For example, when each interface passes through the drain valve at the bottom of the ion exchange tower, it is extracted, and the number of moles of boric acid corresponding to the amount extracted is transferred from the boric acid supply valve at the top of the ion exchange tower to the raw material in the boric acid adsorption zone. The production of 10B and 11B concentrates and the supply of raw material boric acid are carried out by supplying a boric acid feed liquid when a point having the same isotopic composition as boric acid passes through the valve. Method using both reverse breakthrough method and permutation expansion method An example of this method will be explained using FIG. 1 as well. For example, the ion exchange towers from C ₁ to C ₆ are regenerated with an alkaline solution such as sodium hydroxide, then washed with demineralized water, and then connected in series from the C ₁ tower to the C ₄ tower, and the boric acid solution is removed from V ₁₁ . Supply V ₂₄
The liquid is drained from the tube and the boric acid solution is passed through the tube until it reaches a completely equilibrium state. Similarly to the next reverse breakthrough method, the boric acid adsorbed on the resin is developed from V ₁₁ with an acid solution, and the liquid is drained from V ₂₄ . At this time C ₅
The column is supplied with a boric acid solution from V ₁₅ , drained from V ₂₅ , and passed through the C ₅ column until complete equilibrium is reached. Continue to develop by supplying acid from V ₁₁ ,
At the point where the rear end interface of the boric acid adsorption zone moves to the C ₂ tower, the acid supply is switched from V ₁₁ to V ₁₂ , and at the same time, the C ₅ tower is connected after the C ₄ tower and the liquid is drained from V ₂ . Do this. Here, while the rear end interface of the boric acid adsorption zone advances through the C ₂ tower, a boric acid solution is supplied from V ₁₆ to the C ₆ tower, the liquid is drained from V ₂₆ , and boric acid is adsorbed to the C ₆ tower. The C ₁ tower, which has completed its expansion and has become an acid-adsorbing form, is V ₁₁
V 21 is drained and regenerated by supplying alkaline solution from the V ₂₁ and then washed with demineralized water. Next, at the point where the rear end interface of the boric acid adsorption zone development by acid moves to the C tower, the acid supply is switched to V ₁₃ , and after the C ₅ tower, the C ₆
Continue deployment by connecting the tower and draining the V ₂₆ , this time
The C ₁ tower adsorbs boric acid, and the C ₂ tower performs regeneration and water washing. By repeating this operation, 10B becomes concentrated at the rear interface of the boric acid adsorption zone. 10B
When it is concentrated to the target concentration or close to it, the boric acid adsorption zone is treated with acid to stop the boric acid adsorption to the ion exchange tower in front of the ion exchange towers that are deployed in the series, and the ion exchange towers are divided into four ion exchange towers. Perform replacement expansion by switching from the series to the 5-tower series. By repeating the displacement development of the boric acid adsorption zone, regeneration of the developed tower, and water washing, 10B concentration further progressed at the rear end of the boric acid adsorption zone, and after switching to displacement deployment at the front end interface, 10B was accumulated at the rear end interface. 11B will be concentrated in proportion to the concentrated amount of 10B. After that, at appropriate intervals, for example, when the front end and rear end interfaces of the boric acid adsorption zone each pass through a drain valve at the bottom of the column, the 11B concentrate and the 10B concentrate are extracted and the number of moles of raw material corresponding to the number of moles extracted is extracted. The boric acid solution is supplied from the boric acid solution supply valve at the top of the ion exchanger to the same isotopic composition ratio as the raw material boric acid in the boric acid adsorption zone when the boric acid solution passes through the valve. , 10B and 11B concentrates and supply of raw material boric acid. This method is suitable for producing 10B concentrates, especially high concentrates. Next, the present invention will be explained with reference to examples, but the present invention is not limited to the following examples. Example 1 90 parts of styrene, 11 parts of 555 divinylbenzene,
Anion exchange in which a crosslinked copolymer polymerized by adding 90 parts of i-octane as a porosity agent was chloromethylated with chloromethyl methyl ether, and N-methyl-D-glucamine was introduced as a functional group. Resin (acid adsorption capacity 29meq/g - resin, water
65.6%) with an average particle diameter of 100 μm and a uniformity coefficient of 1.3, which was made into a free amine form with a circle diameter of 10 mm and a length of 1000 mm.
Boron isotopes were separated by the reverse breakthrough method by filling 6 glass columns with jackets with 75 ml each, and passing constant temperature water at 60°C through the jackets. That is, first, from the first column, 0.6M boric acid aqueous solution preheated to 60℃ was poured at a flow rate of LV1.
m/hr, and the liquid was drained from the 6th column, and boric acid was adsorbed on the resin in the 6th column. Next, a 0.6N aqueous hydrochloric acid solution preheated to 60°C was passed through the first column at a flow rate of LV1.7 m/hr to develop the boric acid adsorbed on the resin.
The aqueous boric acid solution flowing out from the sixth column was collected in 5 ml portions and the boric acid concentration was measured to be 0.54 M/ml. At this time, from the start of development with 0.6N hydrochloric acid aqueous solution,
It took 64 hours to break through from the 6th column and complete the development, and the moving speed at the rear end interface of the boric acid adsorption zone was 90 cm/hr. Next, when we measured the boron isotope ratio of the fractionated boric acid aqueous solution, we found that the 10B concentration at the last end of the boric acid adsorption zone was
24.5%, and 10B was concentrated at the rear interface of the boric acid adsorption zone over a length of approximately 55 cm. The separation factor calculated from this is 1.015,
HETP was 22mm. Example 2 Diamond ion CRBO2 (functional group: N-methyl-D
- glucamine form) has an average particle size of 100 μm;
1,000 ml of anion exchange resin with a uniformity coefficient of 1.3 was made into a free amine form, and 75 ml of this was packed into six jacketed gas column columns each having an inner diameter of 10 mm and a length of 1,000 mm, and these were connected in series, and 80 ml of the anion exchange resin was packed into the jacket.
The interior of the column was maintained at 80°C by passing constant-temperature water therethrough, and boron isotope separation was performed using the reverse breakthrough method. (Figure 1). In other words, first, 80 from the first tower.
A 0.6 M/boric acid aqueous solution preheated to 20° C. was passed through the reactor at a flow rate (LV) of 1 m/hr, and the liquid was drained from the 6th column to adsorb boric acid onto the resin in the 6th column. Next, a 0.465M aqueous sulfuric acid solution preheated to 80°C was passed through the first column at a flow rate (LV) of 3 m/hr to develop the boric acid adsorbed on the resin, and then from the sixth column The flowing boric acid aqueous solution was collected in 5 ml portions using a franchise collector and the boric acid concentration was analyzed.
It was 0.6M/. The time required from the start of development with the sulfuric acid aqueous solution until the sixth column broke through and the development ended was 5.0 hours, and the moving speed of the rear end interface of the boric acid adsorption zone was 133 cm/hr. . Next, the boron isotope ratio of the fractionated boric acid aqueous solution was measured using a Varian Mats CH-5 solid state mass spectrometer. 10B concentration in acid
It was 24.0% compared to 19.85%, and 10B was concentrated at the rear interface of the boric acid adsorption zone over a length of about 35 cm. The separation coefficient (α ¹⁰ ₁₁ ) calculated from this is
It was 1.015. Comparative Example Using the same equipment and the same anion exchange resin as in Example 1, constant temperature water at 80°C was passed through the jacket.
The inside of the column was kept at 80°C, and boron isotopes were separated using the reverse breakthrough method. That is, the first
A 0.6 M aqueous boric acid solution adjusted to 80° C. was passed through the column at a flow rate of LV 1.0 m/hr, and the liquid was drained from the sixth column to adsorb boric acid. Next, from the first column, a 1.2M sulfuric acid aqueous solution adjusted to 80℃ was introduced at a flow rate of LV3m/
The boric acid aqueous solution flowing out from the 6th column is
The boric acid concentration was analyzed by fractionating each ml using a frankion collector and found it to be 2.1 M/ml. It took 3.2 hours to expand the six towers using an aqueous sulfuric acid solution, and the moving speed at the rear end interface of the boric acid adsorption zone was 175 cm/hr. When the boric acid adsorption zone is developed by the 6-column reverse breakthrough method, the 10B concentration at the end is 19.85% of the 10B concentration in the natural composition raw material boric acid adsorbed initially.
The concentration of 10B was substantially the same as that of 10B.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing an ion exchange resin column, its piping, and valves for carrying out the present invention. _C1 to _C6 ... anion exchange column, _V11 to _V16 ... valve, _V21 to _V26 ... valve, _M1 to _M6 ... detector.

Claims (1)

[Claims] 1. Boric acid is passed through a resin layer made of an aminopolyol type anion exchange resin to form a boric acid adsorption zone, and then expanded with acid to concentrate boron isotopes. A boron isotope characterized in that the concentration of the solution is in the range of 0.2 to 2M/, the temperature during development is in the range of 40 to 100°C, and the concentration of the acid used is in the range of 0.2 to 2M/. Body concentration method.