JPH08269585A - Method for separating and recovering platinum family element and technetium - Google Patents

Abstract

PURPOSE: To obtain a method for separating and recovering platinum family elements and technetium with a high purity at a high yield from the nitric acid soln. of spent unclear fuel or the waste liquids generated from reprocessing plants. CONSTITUTION: The nitric acid soln. of spent nuclear fuel or a waste liquid generated from the reprocessing plant is brought into contact with anion exchange resin to selectively adsorb the platinum family elements, such as palladium and ruthenium, and technetium in the solns. The anion exchange resin is an anion exchange resin consisting of high-molecular polymers as base bodies and having heterocyclic groups contg. nitrogen atoms as functional groups or a weakly basic anion exchange resin having primary to secondary amine groups as functional groups. The ion exchange resin after the adsorption is successively brought into contact with a dilute nitric acid soln., aq. soln. contg. thiourea or ammonia and concd. nitric acid soln., thereby, the ruthenium, palladium and technetium adsorbed on the ion exchange regions are respectively selectively eluted and recovered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating and recovering platinum group elements and technetium from a nitric acid solution of spent nuclear fuel and a waste solution generated at a reprocessing plant.

[0002]

Spent nuclear fuel contains, in addition to nuclear fuel materials such as uranium and plutonium, considerable amounts of useful fission products such as platinum group elements and technetium. In the reprocessing process currently called industrially called the Purex method, spent fuel is dissolved in nitric acid, and then uranium and plutonium are extracted and separated by a solvent extraction method for reuse. Platinum group elements and technetium remain in the extraction residual liquid together with various other fission products, and are treated as radioactive waste liquid. This waste liquid becomes a high-level waste liquid through a nitric acid recovery process and an evaporative concentration process, and is finally planned to be stored and disposed in the deep strata in the form of a vitrified body.

In the above reprocessing process, platinum group elements and valuable metal elements such as technetium are not separated and recovered in any step. Therefore, in the solvent extraction step, solid fine particles called a clad mainly composed of colloidal deposits of platinum group elements are deposited. Since such a clad is formed and accumulated at the interface between the water phase and the organic solvent phase, it interferes with the extraction of uranium and plutonium, and is a major cause of deterioration in separation performance and decontamination performance of fission products. .

Further, in the vitrification step of the high-level liquid waste, radioactive ruthenium oxide which is easily volatilized is generated, so that there is a risk of volatilization and diffusion during high-temperature processing. To solve this, expensive and complicated ruthenium removal is performed. Equipment is required.

The high-level liquid waste contains ⁹⁹ Tc (technetium), which is a radionuclide with a very long half-life, and when the liquid waste is treated, for example, when it is disposed in the geological formation as a vitrified body, it has a long-term environmental impact. It is said that there is a possibility that radioactivity will affect this.

On the other hand, the platinum group element is an extremely important metal element which is used not only in ornaments but also in the fields of electric appliances as electronic materials and electric materials and in the fields of synthetic chemistry, petrochemistry, automobile industry as catalysts. is there. However,
The natural mineral resources of platinum group elements are scarce, and their reserves and production are concentrated in extremely limited countries, which makes the supply system of platinum group elements extremely fragile. In particular, there are almost no platinum group element mines in Japan at present, all of which rely on imports from overseas, the prices are extremely high, and securing raw material supply is an important issue.

On the other hand, the spent nuclear fuel contains a considerable amount of platinum group elements, and the production amount depends on the composition and burnup of the fuel, but 1 t of the spent fuel of a light water reactor with a normal burnup is used.
The amount contained per unit is 850 g of palladium (Pd), 1900 g of ruthenium (Ru), 32 of rhobidium (Rh).
It is about 0 g. If all of these platinum group elements were recovered and their radioactivity was reduced to a sufficient level, the amount of chemical catalysts used in Japan is currently about 36% for palladium, about 60% for ruthenium, and about 1% for rhobidium.
It is a calculation that can be satisfied with 00%. Note that technetium is an element that is not produced in nature at all, and is an element artificially created by the fission reaction. About 750 g of technetium is contained per ton of spent nuclear fuel.

Part of the platinum group elements and technetium in the spent fuel become insoluble residues in the dissolution process, but a considerable part thereof is dissolved in nitric acid and exists in the solution. The amount of these elements dissolved depends on the burnup of the fuel, the concentration of the nitric acid solution used, and the melting temperature. Usually, it is said that almost all palladium, 60 to 90% ruthenium, and about half of technetium are dissolved. ing. Most of rhodium (Rh) is not dissolved but remains in the insoluble residue. These dissolved platinum group elements and technetium are
In addition to U, Pu and other nuclear fuel substances, N
Minor actinide elements such as p, Am and Cm, alkali metal elements such as Cs, alkaline earth metal elements such as Ba and Sr, rare earth metal elements such as Y, Nd and Ce, Mo and Zr,
It coexists with a wide variety of fission products such as Te. In addition, in the high-level radioactive liquid waste generated by improved reprocessing,
It contains small amounts of U, Pu extraction residues and almost all platinum group elements, technetium and the above fission products dissolved in nitric acid. In addition to their complicated composition and diverse chemical properties, these solutions have strong radioactivity, and as a result, effective methods have not yet been established for the separation and recovery of valuable elements in them. is there.

[0009]

Conventionally, since platinum group elements and technetium have not been separated and recovered from a nitric acid solution of spent nuclear fuel or a waste solution generated at a reprocessing plant, platinum group elements and technetium are contained in spent nuclear fuel. There were problems such as obstructing the reprocessing process and the waste disposal process. On the other hand, platinum group elements and technetium are industrially extremely useful metal elements, but there is a problem that these elements cannot be produced domestically and supply is difficult. Therefore, separating and recovering the platinum group element and technetium greatly contributes to improving the performance of the reprocessing process and reducing the radioactivity level of the waste liquid, and at the same time, ensuring the stability of the rare metal raw material.

The present invention has been made to solve the above-mentioned problems, and it is possible to obtain a platinum group element and technetium in a high yield and a high purity from a nitric acid solution of spent nuclear fuel or a waste liquid generated in a reprocessing plant. The purpose is to obtain a method of separation and recovery by.

[0011]

According to a first aspect of the present invention, there is provided a method for separating and recovering platinum group elements and technetium, which comprises contacting a nitric acid solution of spent nuclear fuel or a waste solution generated in a reprocessing plant with an anion exchange resin. It selectively adsorbs platinum group elements such as palladium, ruthenium and technetium.

In the method for separating and recovering platinum group elements and technetium according to the invention of claim 2, the ion exchange resin after adsorbing the platinum group elements and technetium is diluted nitric acid solution, aqueous solution containing thiourea or ammonia, concentrated nitric acid solution. Ruthenium, palladium, and technetium adsorbed on the ion-exchange resin by sequentially contacting with are selectively eluted and recovered.

In the method for separating and recovering a platinum group element and technetium according to the third aspect of the present invention, the anion exchange resin is an anion exchange resin whose base is a polymer and which has a nitrogen atom-containing heterocyclic group as a functional group. It is a weakly basic anion exchange resin having a primary to secondary amine group as a functional group.

The inventors of the present invention firstly separated and recovered platinum group elements and technetium from a nitric acid solution of spent nuclear fuel or a waste liquid generated at a reprocessing plant (these solutions are hereinafter referred to as “treatment liquid”). , The adsorption characteristics of various anion exchange resins for platinum group elements, technetium in nitric acid aqueous solution and various other metal elements contained in the above treatment liquid have been investigated. In particular, as a result of intensive research focusing on the relationship between the adsorption characteristics of platinum group elements and technetium and the functional group structure of the exchanger, it has an exchange group showing strong adsorption power and excellent selectivity for these elements. Several anion exchange resins have been found. These resins are anion exchange resins having a high molecular polymer as a base and having a nitrogen atom-containing heterocyclic group as a functional group, or weakly basic anion exchange resins having a primary to secondary amine group as a functional group. Specific examples of such a functional group include those having the structures shown below.

[0015]

Embedded image

The anion exchange resin having the above functional group is
Since the exchange group contains a nitrogen atom having a strong coordination bond, it exhibits an extremely strong adsorptive power and excellent selectivity to platinum group elements, particularly palladium ions.

An example of the results of measurement of the adsorption characteristics of the platinum group element and technetium on these anion exchange resins is shown. FIG. 1 is a graph showing the nitric acid concentration dependence of the adsorption distribution coefficient on the dipyrrolyl group anion exchange resin of the present invention. In this figure, the vertical axis shows the adsorption distribution coefficient, the horizontal axis shows the nitric acid concentration in mol / liter (mol / l), and the solid line shows palladium (Pd), technetium (Tc), ruthenium (Ru), and dipyrrolyl of rhodium (Rh). Is a measured value of the adsorption distribution coefficient to the base anion exchange resin, and the broken line is a measured value of the adsorption distribution coefficient of palladium (Pd) to the commercially available quaternary ammonium group anion exchange resin which is most often used industrially. . The adsorption partition coefficient is defined as the ratio between the metal concentration in the resin and the metal concentration in the solution at the adsorption equilibrium. From this figure, it can be seen that the adsorption partition coefficient for palladium was found in the wide range of the dipyrrolyl group anion exchange resin of the present invention from a thin acidic side with a nitric acid concentration of about 10 ^-2 M to a concentrated nitric acid of about 12 M. The value is as large as several tens to several hundreds of times that of resin. Further, it can be seen that technetium also exhibits extremely strong adsorptivity in a dilute nitric acid solution. Furthermore, ruthenium exhibits a relatively strong adsorptivity in the nitric acid concentration range of 0.5M to 4M.

When anion exchange resins having a dipyridine group, a primary amine group and a secondary amine group as an exchange group were used for measurement, almost the same results as in FIG. 1 were obtained. On the other hand, these resins show almost the same adsorptivity as the ordinary commercial quaternary ammonium group anion exchange resin for elements other than platinum group elements and technetium, especially other metal elements coexisting in the above treatment liquid. Was confirmed.
Specifically, U, Pu, and Np form a nitrato anion complex when the nitric acid concentration is 2 M or more, and thus are well adsorbed on the anion exchange resin, but the nitric acid concentration is 2 M, particularly 1.5 M.
Below M, no anion complex is formed, and therefore no adsorption occurs. In addition, alkali metal elements such as Cs, Ba,
Alkaline earth metal elements such as Sr, rare earth metal elements such as Nd and Ce, minor actinide elements such as Am and Cm, M
Elements such as o and Zr do not form an anion nitrato complex in a nitric acid solution, and since they all exist in the form of cations, they are not adsorbed on the anion exchange resin at all. Therefore, when the above resin is used, only the platinum group element and technetium in the treatment liquid can be selectively adsorbed and separated from other elements coexisting in the solution.

Further, the inventors of the present invention have conducted further diligent studies in order to separate and collect the platinum group element and technetium adsorbed on the anion exchange resin, and as a result, the following (1) to (3) are described. I found a way to do it. That is,

(1) The ion exchange resin after adsorbing platinum group elements such as palladium and ruthenium and technetium from the treatment liquid is brought into contact with a dilute nitric acid solution, and only the ruthenium adsorbed on the ion exchange resin is selectively selected. Elute and collect. (2) The ion exchange resin after eluting the ruthenium is then contacted with an aqueous solution containing thiourea (SC (NH ₂ ) ₂ ) or ammonia (NH ₃ ), and only palladium adsorbed on the ion exchange resin is selectively selected. Elute and collect. (3) The ion exchange resin after eluting the palladium is then contacted with a concentrated nitric acid solution to selectively elute and collect the technetium adsorbed on the ion exchange resin. Hereinafter, the present invention will be described in more detail by dividing it into a solution preparation step, an adsorption step, and an elution recovery step.

Solution adjusting step In the present invention, first, the nitric acid concentration in the treatment liquid is adjusted to a range of 0.01 to 2 N, preferably 0.1 to 1.5 N. When the nitric acid concentration in these solutions is 0.01 N or less, the ions of various metal elements including platinum group elements in the solution are precipitated by the hydrolysis reaction, and the adsorbability to the ion exchanger decreases in the next adsorption step. Resulting in.

On the other hand, when the nitrate concentration in the solution is 2N or more, large amount of NO ₃ in the solution ^- ion present, U coexist in solution in the solution, especially spent fuel ^4+, UO ₂ ²⁺ , P
Metal ions such as u ⁴⁺ and Np ⁴⁺ form an anion complex with NO ₃ ⁻ . Since these anion complexes have strong adsorptivity to the anion exchanger, it becomes difficult to separate them from the platinum group element and technetium. The nitric acid concentration in the solution can be easily adjusted by adding nitric acid or pure water. In some cases, known chemical denitration method or electrolytic denitration method can be used.

Adsorption step By bringing the solution obtained in the solution preparation step into contact with the anion exchange resin, only palladium, ruthenium, and technetium in the solution are adsorbed by the resin and transferred from the solution phase to the resin phase. Separated from other elements. In addition,
Ruthenium is adsorbed mainly in the form of an anion complex of nitrosyl nitrato, and technetium is adsorbed in the form of TcO ₄ ⁻ anion. On the other hand, in the case of palladium, Pd is mainly used in the solution.
^Although it exists in the form of ²⁺ , since the functional group of the resin contains a nitrogen atom having a strong coordination bond, the palladium ion and the N atom in the functional group form a stable complex by the coordination bond. As a result, palladium is strongly adsorbed.

As the adsorption operation, known column type and batch type are preferably used. That is, in the column type, the ion exchange resin is packed in a column and the treatment liquid is passed through to adsorb palladium, ruthenium, and technetium in the solution onto the resin. In the batch system, the treatment liquid and the ion exchange resin are put in a container and stirred or shaken to adsorb palladium, ruthenium, and technetium in the solution onto the resin. The shape of the ion-exchange resin used is not particularly limited, and macroporous type, gel type or carrier-supporting type spherical resin particles having a particle size of about several tens to several hundreds of micron which are usually used industrially are preferably used. . Also, the adsorption temperature is not particularly limited, and may be in the range of room temperature to 80 ° C. which is usually industrially easily realized. The adsorption rate can be accelerated to some extent by raising the temperature.

Elution recovery step The platinum group element and technetium adsorbed on the anion exchange resin through the adsorption step are separated and recovered by the elution steps described in (a) to (c) below, and at the same time, the resin is regenerated. Can be reused. That is, (a) Ruthenium elution step As shown in FIG. 1, when the nitric acid concentration is 0.05 M or less, the distribution coefficient of ruthenium sharply decreases and the ruthenium is hardly adsorbed on the anion exchange resin. Therefore, by contacting the ion exchange resin that has undergone the adsorption step with a dilute nitric acid solution, only ruthenium adsorbed on the resin can be selectively eluted.
The nitric acid concentration used as the eluent was 0.001M to 0.
It is preferably in the range of 05M. Nitric acid concentration 0.05
Above M, ruthenium is not completely eluted because it is adsorbed on the resin. On the other hand, when the nitric acid concentration is 0.001 M or less,
There is a risk that a part of ruthenium will be hydrolyzed into a hydroxide or an oxide precipitate and will stick to the surface or pores of the resin particles and not be eluted.

(B) Palladium Elution Step As shown in FIG. 1, palladium exhibits strong adsorptivity in a wide nitric acid concentration range of 12 M or less, and elution of palladium cannot be expected in this nitric acid concentration range. On the other hand, when the concentration of concentrated nitric acid is 12 M or more, the adsorption becomes weak, and there is a possibility that it will be eluted by the concentrated nitric acid of 12 M or more. However, when concentrated nitric acid is used as an eluent, technetium is also eluted (see FIG. 1), and thus it becomes difficult to separate the two. In order to selectively elute and recover palladium, the present inventors diligently studied various eluents and elution conditions, and as a result, thiourea (SC (NH
₂ ) ₂ ) and ammonia (NH ₃ ) have been found to be very good eluents for palladium. These reagents have a strong ability to form a complex with a palladium ion through a coordinate bond of a nitrogen atom, and form a stable cation complex such as PdXn ²⁺ (X = SC (NH ₂ ) ₂ or NH ₃ , n = 1 to 4). Form. Therefore, the palladium adsorbed on the anion exchange resin is eluted from the resin by the ligand substitution reaction with these eluents. Thiourea reagent is water soluble,
Dissolve this in water or nitric acid acidic aqueous solution to 0.1 to several M
It is preferably used as a thiourea solution. On the other hand, NH ₃
As the eluent, commercially available ammonia water may be diluted to about 0.1 to several M and used. The concentrations of these reagents as the eluent are not particularly limited. On the other hand, as a matter of course, the amount of the eluent used needs to correspond to the amount of adsorbed palladium, and according to the results of studies by the present inventors, the amount adsorbed with palladium is at least twice the molar amount, preferably at least four times the molar amount. If so, the adsorbed palladium can be selectively and completely eluted.

(C) Technetium Elution Step The ion exchange resin after the palladium is eluted is then contacted with a concentrated nitric acid solution to elute and recover the technetium adsorbed on the ion exchange resin. As shown in FIG. 1, technetium strongly adsorbs to the resin in a dilute nitric acid solution, but the adsorption decreases sharply as the nitric acid concentration increases, and is almost not adsorbed at about 9 M or more. According to the results of studies by the present inventors, when a concentrated nitric acid solution of about 9 M to 14 M is used as an eluent, the total amount of technetium adsorbed on the resin can be recovered. When the elution of technetium is completed, the resin becomes a type in which NO ₃ ⁻ is adsorbed, that is, the resin is regenerated and can be used in the next adsorption step.

The elution operations (a) to (c) above are carried out in the same manner as in the column type and the batch type described in the adsorption step. The adsorbed ruthenium, palladium, and technetium metal ions are sequentially eluted and transferred from the resin phase to the solution phase for separation and recovery. The temperature of the elution operation is industrially easily achieved at room temperature to 80 as well as the adsorption step.
C may be sufficient.

[0029]

According to the method for separating and recovering platinum group elements and technetium in the invention of claim 1, when the nitric acid solution of the spent nuclear fuel or the waste solution generated in the reprocessing plant is brought into contact with the anion exchange resin, the anion exchange resin is converted into the platinum group. Since it has a strong adsorption force for elements and technetium and excellent selectivity, platinum group elements and technetium are selectively adsorbed.

In the method for separating and recovering platinum group elements and technetium in the invention of claim 2, the ion exchange resin after adsorbing the platinum group elements and technetium is formed into a dilute nitric acid solution, an aqueous solution containing thiourea or ammonia, or a concentrated nitric acid solution. When they are sequentially contacted, these solutions are eluents for ruthenium, palladium, and technetium, respectively, so that ruthenium, palladium, and technetium are selectively eluted and recovered.

In the method for separating and recovering the platinum group element and technetium according to the invention of claim 3, the anion exchange resin is an anion exchange resin having a polymer polymer as a base material and a nitrogen atom-containing heterocyclic group as a functional group, or 1 ~ It is a weakly basic anion exchange resin having a secondary amine group as a functional group, and because the exchange group contains a nitrogen atom having a strong coordination bond, it has an extremely strong adsorption force for platinum group elements, especially palladium ions. And has excellent selectivity.

[0032]

【Example】

Example 1. Adsorption process and cleaning process: inner diameter 1 cm, length 2
Exchange capacity 3.4 meq / g in a 0 cm glass column
15 cm of the dipyrrolyl group anion exchange resin of (6) was filled (resin weight: about 6 g), and the whole column was kept at a constant temperature of 60 ° C. From the top of the column, Pd 504.7 mg / l,
Ru 503.8 mg / l, Rh 251.7 mg /
1, Tc 517.1 mg / l, Cs 998.2 mg
/ L, Sr 1022.4mg / l, Y 501.3m
g / l, Nd 1017.7 mg / l, Mo492.3
mg / l, Zr 503.6 mg / l, nitric acid concentration 1 m
After 50 ml of the simulated spent nuclear fuel reprocessing waste liquid having a composition such as ol / l was passed at a flow rate of 5 ml / min, 50 ml of a nitric acid aqueous solution having a concentration of 1 M was subsequently flown to wash the exchanger and the column. The solution flowing out from the lower end of the column was collected by a fraction collector every 10 ml.

Ruthenium elution step: then 0.05M
50 ml of the diluted nitric acid solution was passed through by the same operation as above, and the outflow liquid was collected by the same operation as above. Palladium elution step: then 0.05M as eluent
Instead of dilute nitric acid solution containing 0.05M thiourea
The same operation as the above ruthenium elution step was performed except that a 1 M nitric acid solution was used.

Technetium elution step: Then, the same operation as the above ruthenium elution step was performed except that a 12M nitric acid solution was used as an eluent instead of the 0.05M dilute nitric acid solution. The metal concentration in each fraction effluent was quantitatively analyzed by high frequency inductively coupled plasma (ICP) emission spectrometry.
FIG. 2 is a graph showing the results of this quantitative analysis, in which the vertical axis represents the concentration (mg / l) in the effluent and the horizontal axis represents the fraction No. of the effluent in the above process. Indicates. From the figure, palladium, which is the metal for separation and recovery of the present invention,
It can be seen that metal elements other than ruthenium and technetium were hardly adsorbed by the resin and were collected in the effluent of the adsorption step and the subsequent washing step. In addition, palladium,
It can be seen that the target metal elements of ruthenium and technetium were separated from each other and concentrated and recovered in the respective eluates.

Example 2. Adsorption process: 200 ml of simulated spent nuclear fuel solution (nitric acid concentration 1.5 M) having the composition shown in Table 1 as the treatment liquid was added to the volume 3
Transfer to a 00 ml Erlenmeyer flask with ground stopper, put 5 g of a weakly basic anion exchange resin containing both primary and secondary amine groups with an exchange capacity of 5.5 meq / g, and set it in a constant temperature water bath adjusted to 30 ° C. And shaken for 5 hours. afterwards,
The resin was separated from the adsorption residual liquid by a glass filter.

Ruthenium elution step: then 0.05M
50 ml of the dilute nitric acid solution was placed in an Erlenmeyer flask with a capacity of 100 ml, and the resin separated from the adsorption residual liquid was put therein and set in a constant temperature water bath adjusted to 30 ° C.
Shake for a minute. The resin was then separated from the eluent by a glass filter.

Palladium elution step: Then, the same operation as the above ruthenium elution step was performed except that a 0.1M nitric acid solution containing 0.2M thiourea was used as the eluent instead of the 0.05M dilute nitric acid solution. went.

Technetium elution step: Then, the same operation as the above ruthenium elution step was performed except that a 10M nitric acid solution was used as an eluent instead of the 0.05M dilute nitric acid solution. The metal concentration in each of the above solutions is determined by the high frequency inductive coupling plasma
CP) Quantitative analysis was carried out by emission spectrometry. The results are shown in Table 1.
Shown in

[0039]

[Table 1]

The recoveries of palladium, ruthenium and technetium, which are the metals for separation and recovery of the present invention, obtained from the results in the table are 95.3%, 86.8% and 89.5%, respectively.
Met. It can be seen that metal elements other than palladium, ruthenium and technetium were hardly adsorbed by the resin and remained in the adsorption residual liquid. Further, other metal elements were hardly detected in the eluate of each target element, and the total concentration was 5 mg / l or less in all cases.

In the above palladium elution step,
When a 0.5M aqueous ammonia solution was used instead of a 0.1M nitric acid solution containing 0.2M thiourea as an eluent,
The metal concentration in the palladium eluate was Pd 1917.3 m.
g / l, Ru 1.54mg / l, Tc 0.38mg
/ L, and the recovery rate of palladium was 95.1%. That is, the same effect as thiourea was observed.

[0042]

As described above, according to the first aspect of the present invention, the nitric acid solution of the spent nuclear fuel or the waste liquid generated in the reprocessing plant is brought into contact with the anion exchange resin. Has a strong adsorption force for platinum group elements and technetium and an excellent selectivity, so that platinum group elements and technetium can be selectively adsorbed.
Therefore, it is possible to prevent the generation of clad in the solvent extraction step and improve the performance of the reprocessing process. In addition, the radioactivity level of the reprocessing waste liquid is reduced, which has the effect of enhancing the safety and economic efficiency in processing and disposal.

According to the second aspect of the present invention, the ion exchange resin after adsorbing the platinum group element and technetium is constituted to be brought into contact with a dilute nitric acid solution, an aqueous solution containing thiourea or ammonia, and a concentrated nitric acid solution in that order. ,ruthenium,
Palladium and technetium can be selectively eluted and recovered. Therefore, there is an effect that it can greatly contribute to securing stable supply of rare metal raw materials in the future.

According to the third aspect of the present invention, the anion exchange resin has a high molecular polymer as a base material and an anion exchange resin having a nitrogen atom-containing heterocyclic group as a functional group or a primary or secondary amine group as a functional group. Since it is composed of a weakly basic anion exchange resin, it has an effect of having extremely strong adsorptivity for platinum group elements, particularly palladium ions, and excellent selectivity.

The method of the present invention is a reliable ion exchange process which is carried out with relatively simple equipment and easy operation, and is economical and rational to carry out industrially.

[Brief description of drawings]

FIG. 1 is a graph showing the dependence of adsorption partition coefficient on a dipyrrolyl group anion exchange resin of the present invention in nitric acid concentration.

FIG. 2 is a graph showing a metal concentration in a fraction effluent in each step according to Example 2 of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location G21F 9/06 581 G21F 9/06 581J (72) Inventor Mikiro Kumagai 4-Matsuba-cho, Kashiwa-shi, Chiba 7-204 (72) Inventor Yoichi Takashima 7-18-19 Ebara, Shinagawa-ku, Tokyo 7-18-19 (72) Kunihiko Takeda Kunihiko Takeda 2-12-5 Nakazato, Minami-ku, Yokohama (72) Kazuhiro Suzuki, Yokohama, Kanagawa 4-1, Egasaki-cho, Tsurumi-ku, TEPCO Ltd. Nuclear Research Institute (72) Inventor Takashi Namba 4-1-1, Egasaki-cho, Tsurumi-ku, Yokohama-shi, Kanagawa TEPCO Ltd. Atomic Energy Research Institute (72) Inventor Masami Aso, 4-1, Egasaki-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture, Atomic Energy Research Institute, Tokyo Electric Power Co., Inc. (72) Inventor, Hokei Hori, 3-3-22 Nakanoshima, Kita-ku, Osaka City Kansai Electric Power Co., Inc. Within the company (72) inventor Nin Oe, Kita-ku, Osaka Nakanoshima 3-chome No. 3 No. 22 Kansai Electric Power Co., Ltd. in the (72) inventor Akira Maekawa Kita-ku, Osaka Nakanoshima 3-chome No. 3 No. 22 Kansai Electric Power Co., Ltd. in

Claims (3)

[Claims] 1. A nitric acid solution of spent nuclear fuel or a waste liquid generated at a reprocessing plant is contacted with an anion exchange resin,
A method for separating and recovering platinum group elements and technetium, which comprises selectively adsorbing platinum group elements such as palladium and ruthenium and technetium in a solution. 2. The ion exchange resin after adsorbing the platinum group element and technetium is contacted with a dilute nitric acid solution to selectively elute ruthenium adsorbed on the ion exchange resin, and then the ion exchange resin is adsorbed on the ion exchange resin. Selectively elute palladium adsorbed on the ion exchange resin by contact with an aqueous solution containing thiourea or ammonia, and then elute and collect technetium adsorbed on the ion exchange resin by contacting the ion exchange resin with a concentrated nitric acid solution. The method for separating and recovering a platinum group element and technetium according to claim 1, wherein 3. The anion exchange resin is based on a polymer, and is an anion exchange resin having a nitrogen atom-containing heterocyclic group as a functional group or a weakly basic anion exchange having a primary or secondary amine group as a functional group. The method for separating and recovering platinum group element and technetium according to claim 1 or 2, which is a resin.