Process for treating plutonium retained in the residual organic phase of the PUREX process
The use of 2,6-pyridinedicarboxylic acid in the PUREX process effectively recovers plutonium from the residual organic phase by re-extraction and ion exchange, addressing the separation challenges and achieving high recovery rates.
Patent Information
- Application Number
- FR2022009632
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Priority Date
- 2022-02-17
- Filing Date
- 2022-09-22
- Publication Date
- 2025-10-17
- Estimated Expiration
- 2042-09-22
AI Technical Summary
The PUREX process faces challenges in effectively separating and recovering plutonium from the residual organic phase due to the formation of stable complexes with degradation products like HDBP and H2MBP, leading to retention and difficulty in phase separation, which is exacerbated by long-term storage.
A method involving the use of an aqueous phase re-extraction solution containing 2,6-pyridinedicarboxylic acid to facilitate the migration of plutonium from the organic phase to the aqueous phase, followed by adsorption and elution using an anion exchange resin, optimizing conditions such as pH, temperature, and acid concentration to enhance recovery.
The method achieves greater than 99% recovery of plutonium from the residual organic phase, reducing its content to less than 0.1 mg/L, meeting waste treatment standards.
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Abstract
Description
Title of the invention: Process for treating plutonium retained in the residual organic phase of the PUREX process Technical field
[0001] The present invention relates to the field of treatment of radioactive waste, in particular a process for treating plutonium retained in the residual organic phase of the PUREX process. STATE OF THE ART
[0002] The PUREX (Plutonium Uranium Reduction Extraction) process is currently the only commercial process for reprocessing spent fuel. In this process, the TBP - kerosene - HNO3 system is subjected to chemical and radiological degradation under the action of chemistry and radiation, and the degradation products of TBP are mainly dibutyl phosphate (HDBP), monobutyl phosphate (H2MBP) and H3PO4, and a diluent and a nitric acid are degraded to produce aldehydes, carboxylic acids and organic nitro compounds such as hydroxamic acids.Among the above degradation products, HDBP and H2MBP are prone to form complexes with Pu(IV) and Zr(IV), and the binding energy of these complexes is higher than that of the complexes formed by Pu(IV) and Zr(IV) with TBP, and are less prone to be back-extracted in the re-extraction section, resulting in the retention of their metal ions in an organic phase. With the continuation of the production operation, the degradation products continue to accumulate in the organic phase, and the degradation products and metal ions form complexes that have low solubility in the organic phase, resulting in difficulties in phase separation.
[0003] In order to reduce the harmful effects of degradation product accumulation on the extraction process, Na2CO3 is often used to wash the degradation products in the organic phase, but it still cannot solve the problem of metallic plutonium retention in the waste organic phase. Therefore, it is urgent to develop a method for eluting and recovering plutonium from the waste organic phase of the spent fuel post-treatment process (especially the waste organic phase with high plutonium content which has been stored for a long time). SUMMARY
[0004] The aim of the present invention is to provide a method for treating plutonium retained in the residual organic phase of the PUREX process, which makes it possible to elute and efficiently recover a high quantity of plutonium retained in the phase residual organic phase, or even in a residual organic phase with a high quantity of retained plutonium stored for a long time.
[0005] In order to achieve the above object, the present invention provides a method for treating plutonium retained in the waste organic phase of the PUREX process. The waste organic phase of the PUREX process contains an organic solvent and plutonium, and the method comprises: contacting the waste organic phase of the PUREX process with an aqueous phase re-extraction solution containing 2,6-pyridinedicarboxylic acid to perform re-extraction, in order to obtain a re-extraction product.
[0006] Optionally, the weight ratio of the aqueous phase re-extraction solution containing 2,6-pyridinedicarboxylic acid relative to the residual organic phase is 1:(1-10), preferably is 1:(1-5).
[0007] Optionally, the content of 2,6-pyridinedicarboxylic acid in the aqueous phase re-extraction solution is 0.1 to 0.7% by weight, preferably 0.3 to 0.5% by weight.
[0008] Optionally, the re-extraction is carried out at a temperature of between 10 and 40°C, preferably between 20 and 30°C, at a stirring speed of between 400 and 700 rpm, preferably between 500 and 600 rpm, for a duration of between 10 and 30 minutes, preferably between 15 and 20 minutes.
[0009] Optionally, the method further comprises: S1, contacting the re-extraction product with an anion exchange resin, so that plutonium in the re-extraction product is adsorbed on the anion exchange resin to obtain a plutonium-adsorbed anion exchange resin; S2, contacting the plutonium-adsorbing anion exchange resin with a transformation liquid to obtain a transformed plutonium-adsorbing anion exchange resin; S3, contacting the transformed plutonium-adsorbing anion exchange resin with an eluent to obtain an elution product.
[0010] Optionally, step S1 comprises bringing the re-extraction product into contact with the anion exchange resin after adjusting the pH of the re-extraction product to a value between 1 and 4.
[0011] Optionally, the transformation liquid contains between 7 and 8 mol / L of nitric acid.
[0012] Optionally, the eluent comprises between 0.3 and 1.0 mol / L of an aqueous solution of nitric acid, or the eluent is an aqueous solution containing between 0.3 and 1.0 mol / L of nitric acid and between 0.05 and 0.15 mol / L of NH20H.
[0013] Optionally, the anion exchange resin comprises at least one resin selected from DOWEX® resin, D201 resin and Diaion® PA 308 resin, preferably DOWEX® 1x4 anion exchange resin.
[0014] Optionally, the method further comprises: before contacting the waste organic phase of the PUREX process with the aqueous re-extraction solution containing 2,6-pyridinedicarboxylic acid, contacting the waste organic phase of the PUREX process with demineralized water and / or an alkaline solution for deacidification. In the present invention, the deacidification of the waste organic phase is not particularly limited, and depending on the residual acid content in the waste organic phase, an alkaline solution, such as a sodium hydroxide solution, may be added to the aqueous phase re-extraction solution for deacidification.
[0015] By means of the above technical solutions, the present invention provides a method for treating plutonium retained in the residual organic phase of the PUREX process, which can effectively elute and recover metallic plutonium in the residual organic phase with high plutonium retention, and a large portion of the metallic plutonium is eluted into the aqueous phase; the plutonium content in the eluted residual organic phase can be less than 0.1 mg / L and at least 99% of the plutonium in the aqueous phase is recovered, which meets the requirements of waste treatment techniques in terms of plutonium content in the residual organic phase.
[0016] Other characteristics and advantages of the invention will be detailed in the detailed description which follows. BRIEF DESCRIPTION OF THE FIGURES
[0017] [Fig.l] [Fig.l] shows the variation of the counting rate of an eluate from an anion exchange column as a function of the volume of the eluate. DETAILED DESCRIPTION
[0018] Specific embodiments of the present invention will be described in detail below with reference to the accompanying figure. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, but not to limit the present invention.
[0019] The present invention provides a method for treating plutonium retained in the waste organic phase of the PUREX process. The waste organic phase of the PUREX process comprises an organic solvent and plutonium, and the method comprises contacting the waste organic phase of the PUREX process with an aqueous phase reextraction solution containing 2,6-pyridinedicarboxylic acid to perform reextraction, to obtain a reextraction product.
[0020] According to the method of the invention, in the re-extraction process, the plutonium can migrate from the residual organic phase of the PUREX process to the phase aqueous solution containing 2,6-pyridinedicarboxylic acid, i.e. in the re-extraction product.
[0021] The weight ratio of the aqueous phase re-extraction solution containing 2,6-pyridinedicarboxylic acid relative to the residual organic phase can vary within a wide range; in a preferred embodiment, the weight ratio of the aqueous phase re-extraction solution containing 2,6-pyridinedicarboxylic acid relative to the residual organic phase is 1:(1-10), more preferably 1:(1-5).
[0022] The content of 2,6-pyridinedicarboxylic acid in the aqueous phase re-extraction solution can make the dispersion coefficient of plutonium in the aqueous phase re-extraction solution greater than the dispersion coefficient of plutonium in the residual organic phase of the PUREX process. In a preferred embodiment, the content of 2,6-pyridinedicarboxylic acid in the aqueous phase re-extraction solution is between 0.1 and 0.7% by weight, preferably between 0.3 and 0.5% by weight.
[0023] The re-extraction conditions in the present invention are not particularly limited, and the person skilled in the art can select them according to actual needs. The re-extraction rate of the plutonium retained in the waste organic phase obtained by the re-extraction conditions defined in the present description is higher and can meet the requirements for the plutonium content of the waste organic phase in the waste treatment technology. For example, in one embodiment, the re-extraction is carried out at a temperature of 5 to 40°C, preferably 20 to 30°C, at a stirring speed of 400 to 700 rpm, preferably 500 to 600 rpm, for a time of 5 to 30 min, preferably 15 to 20 min.
[0024] After the re-extraction, plutonium may also be extracted from the obtained re-extraction product by means of adsorption and elution using an ion exchange resin, and therefore, the method may preferably further comprise: S1, contacting the re-extraction product with an anion exchange resin, so that the plutonium in the re-extraction product is adsorbed on the anion exchange resin to obtain a plutonium-adsorbed anion exchange resin; S2, contacting the plutonium-adsorbed anion exchange resin with a transformation liquid to obtain the transformed plutonium-adsorbed anion exchange resin; and S3, contacting the transformed plutonium-adsorbed anion exchange resin with an eluent to obtain an elution product. The elution product contains extracted plutonium.
[0025] In order to allow the anion exchange resin to better adsorb the plutonium, preferably, step S1 further comprises, before it is brought into contact with the resin anion exchanger, adjusting the pH of the re-extraction product to a value between 1 and 4.
[0026] In order to obtain a better transformation effect, preferably the transformation liquid contains between 7 and 8 mol / L of nitric acid.
[0027] In order to obtain a better elution effect, preferably, the eluent comprises between 0.3 and 1.0 mol / L of an aqueous solution of nitric acid, or the eluent is an aqueous solution containing between 0.3 and 1.0 mol / L of nitric acid and between 0.05 and 0.15 mol / L of NH2OH.
[0028] In order to enable the anion exchange resin to better adsorb plutonium, preferably the anion exchange resin comprises at least one resin selected from DOWEX® resin, D201 resin and Diaion® PA 308 resin, preferably DOWEX® 1x4 anion exchange resin.
[0029] In order to prevent an acid in the waste organic phase from affecting the re-extraction, preferably, the method further comprises, before contacting the waste organic phase of the PUREX process with the aqueous phase re-extraction solution containing 2,6-pyridinedicarboxylic acid, contacting the waste organic phase of the PUREX process with deionized water and / or an alkaline solution for deacidification, and the pH value of the waste organic phase after deacidification is between 0.5 and 3. In the present description, the deacidification of the waste organic phase is not particularly limited, and depending on the residual acid content in the waste organic phase, an alkaline solution, such as a sodium hydroxide solution, may be added to the aqueous phase re-extraction solution for deacidification.
[0030] The present invention is further illustrated by the following examples, but the present invention is not limited thereto.
[0031] Example 1
[0032] A 2BW feed solution obtained from a thermal experiment of a PUREX process research conducted by the 'Chinese Academy of Atomic Energy Sciences' was used as a processing object; the feed solution was a waste organic phase with an excessive plutonium content obtained from the plutonium purification cycle, and was subjected to plutonium elution using a dilute acid solution, a tetravalent uranium solution, an N,N-dimethylhydroxylamine solution and a sodium carbonate solution, respectively during the experiment.Its main chemical components were: 30 vol% tributyl phosphate (TBP) and 70 vol% hydrogenated kerosene, in which the plutonium content is 0.057 g / L, the nitric acid content is 0.03 mol / L, and the dibutyl phosphate (DBP) content is 0.9 mmol / L, the monobutyl phosphate (MBP) content is 0.23 mmol / L, and the contents of others. degradation products and metal ions were not determined. Prior to this experiment, the feed solution had been stored for more than 5 years and appeared as a clear, yellowish-brown solution.
[0033] The treatment process was as follows: 1. 10 ql of the above residual organic phase was taken for measurement of liquid scintillation, and the content of 239+240pu in the residual organic phase was calculated to be 0.057g / L; deionized water was added to the residual organic phase, and mixed with the residual organic phase in a volume ratio of 1:1; the mixture was stirred at room temperature for 5 min to remove the residual acid from the residual organic phase; 2. 20.87 mg of solid DPA (2,6-pyridinedicarboxylic acid) was weighed and added into a centrifuge tube, and then 5 ml of 0.4 mol / L nitric acid solution was added to prepare an aqueous phase re-extraction solution containing 0.025 mol / L DPA and 0.4 mol / L HNO3. 3. 1.0 mL of the mentioned residual organic phase containing plutonium above was added into a 15ml polypropylene centrifuge tube, then 1.0mL of the above-mentioned DPA-HNO3 aqueous phase re-extraction solution was added into the centrifuge tube, and the mixture was stirred at room temperature for 5 min; then, after centrifugation at 4000 rpm for 5 min, 10 qL of an organic phase was taken for liquid scintillation measurement, and the primary plutonium re-extraction rate was calculated to be 97.1%. Plutonium re-extraction rate (%) = l-(plutonium content in the residual organic phase after elution) / (plutonium content in the initial residual organic phase) x 100% 4. a lower aqueous phase generated in step (3) was removed, and 1.0 mL of a DPA-HNO3 solution at the same concentration was added back to the organic phase, and the mixture was stirred for 5 minutes at room temperature; and, after centrifugation, 10 qL of an organic phase was taken for liquid scintillation measurement, and a secondary plutonium re-extraction rate was calculated to be 92.6%, and the total re-extraction rate was calculated to be 99.78%, as shown in Table 1.
[0034] Example 2
[0035] This example adopted the same method as that of Example 1, except that the re-extraction solution used in this example was a DPA solution at a concentration of 0.025 mol / L, and a re-extraction rate of plutonium is shown in Table 1.
[0036] Example 3
[0037] This example adopts the same method as that of Example 1, except that the concentration of DPA in the aqueous phase reextraction solution used in this example is 0.025 mol / L, and the concentration of HNO3 is 0.2 mol / L, and a plutonium reextraction rate is shown in Table 1.
[0038] Example 4
[0039] This example adopts the same method as that of Example 1, except that the concentration of DPA in the aqueous phase reextraction solution used in this example is 0.025 mol / L, and the concentration of HNO3 is 0.8 mol / L, and a plutonium reextraction rate is shown in Table 1.
[0040] Example 5
[0041] This example adopts the same method as that of Example 1, except that the re-extraction solution used in this example is a DPA-HNO3 mixed solution, in which the concentration of DPA is 0.025 mol / L and the concentration of HNO3 is 1.5 mol / L, and a re-extraction rate of plutonium is shown in Table 1.
[0042] Example 6
[0043] This example adopts the same method as that of Example 1, except that the re-extraction solution used in this example is a DPA-HNO3 mixed solution, in which the concentration of DPA is 0.025 mol / L and the concentration of HNO3 is 3.0 mol / L, and a re-extraction rate of plutonium is shown in Table 1. [Tables 1] Example concentration of DPA Concentration of HNO3 Phase ratio (a:o) Primary re-extraction rate Secondary re-extraction rate Total re-extraction rate 1 0.025 mol / 1 0.4 mol / 1 1:1 96.8% 92.2% 99.75% 2 0.025 mol / 1 0 mol / 1 1:1 97.3% 92.2% 99.79% 3 0.025 mol / 1 0.2 mol / 1 1:1 97.1% 92.6% 99.78% 4 0.025 mol / 1 0.8 mol / 1 1:1 97.4% 90% 99.74% 5 0.025 mol / 1 1.5mol / 1 1:1 95.4% 91.2% 99.59% 6 0.025 mol / 1 3.0 mol / 1 1:1 95.7% 86.2% 99.4%
[0044] The results in Table 1 show that: when a phase ratio of the waste organic phase to the aqueous phase re-extraction solution was 1:1, the concentration of DPA was 0.025 mol / L, the concentration of HNO3 was increased from 0 mol / L to 3.0 mol / L, the primary re-extraction rate was greater than or equal to 95%, and the secondary re-extraction rate was greater than or equal to 86%, the use of DPA as the re-extraction agent enables efficient re-extraction of the plutonium retained in the residual organic phase, and, after the addition of nitric acid, although the acidity has a slightly inhibiting effect on the plutonium re-extraction rate, plutonium can be efficiently re-extracted in HNO3 solution at a concentration between 0 and 3.0 mol / L.
[0045] Example 7
[0046] This example adopts the same method as that of Example 1, except that the re-extraction was carried out 5 times, and a re-extraction rate is shown in Table 2.
[0047] Example 8
[0048] This example adopts the same method as that of Example 1, except that the phase ratio of the aqueous phase re-extraction solution to the residual organic phase is 1:5, and the re-extraction was carried out 5 times, and a re-extraction rate is shown in Table 2.
[0049] Example 9
[0050] This example adopts the same method as that of Example 1, except that the phase ratio of the aqueous phase re-extraction solution to the residual organic phase is 1:10, and the re-extraction was carried out 5 times, and a re-extraction rate is shown in Table 2. [Tables 2] Example Phase Ratio (a:o) Primary Re-extraction Rate Secondary Re-extraction Rate Third Re-extraction Rate Fourth Re-extraction Rate Fifth Re-extraction Rate Early Re-extraction Rate 7 1:1 99.87% 50.19% 57.04% 25.04% 10.35% 99.98% 8 1:5 94.7% 67.6% 65.0% 52.1% 50.3% 99.86% 9 1:10 93.7% 68.1% 66.5% 53.1% 48.9% 99.84%
[0051] The results in Table 2 show that DPA was used as a complexing agent to effectively re-extract the plutonium retained in the residual organic phase of the post-treatment process in an acidic solution. Even when the phase ratio (organic phase: aqueous phase) was 10:1, the re-extraction rate of plutonium in a single step can reach more than 90%, and, if the DPA concentration, reaction temperature, and acidity of the aqueous phase were further optimized or multi-stage re-extraction was used, the single-stage re-extraction rate of plutonium can reach 99.9% under the condition that the phase ratio of organic phase to aqueous phase was 10:1.
[0052] Example 10
[0053] The 2BW feed solution obtained from a thermal experiment of a post-treatment process research conducted by the 'Chinese Academy of Atomic Energy Sciences' was used as the processing object. The feed solution was a contaminated solvent with excessive plutonium content obtained from the plutonium purification cycle. During the experiment, the elution of plutonium was carried out separately using a dilute acid solution, a tetravalent uranium solution, an N,N-dimethylhydroxylamine solution, and a sodium carbonate solution.Its main chemical components were: 30 vol% tributyl phosphate (TBP) and 70 vol% hydrogenated kerosene, with a plutonium content of 0.057 g / L, a nitric acid content of 0.03 mol / L, and a dibutyl phosphate (DBP) content of 0.9 mmol / L, a monobutyl phosphate (MBP) content of 2.30x10 4 mol / L, a trace amount of tetravalent uranium was negligible, and the contents of other degradation products and metal ions were not determined. Before this experiment, the feed solution was stored for more than 5 years and its appearance was that of a clear solution with a yellowish-brown color.
[0054] A recycling process was as follows: 1. A jacketed ion exchange column was connected to inlet and outlet lines of a water bath tank, the water bath temperature was controlled at 60 °C, and the anion exchange resin was selected as DOWEX® 1x4, 100-200 mesh. After soaking the resin in deionized water for 24 hours, the resin was loaded into the column with a column volume of 1 mL. The resin was transformed with 10 mL of 1M HNO3 solution; after transformation, the deionized water was used to rinse the column until the eluate was neutral. 2. 0.025 mol / L DPA solution was used as the aqueous re-extraction agent. The aqueous re-extraction product after the first re-extraction was used as a solution that was loaded onto a column. The 0-21 keV count measured with 10 qL of the solution is 3631225; 0.3 mL of the solution that had been loaded onto the column was added into the anion exchange column, and then elution was performed with 5 mL of 0.025 mol / L DPA solution. 1 mL of the eluate was taken out each time, and 10 qL of the eluate was taken respectively to measure a 0-21 keV count rate. 3. Pu(IV) desorption was carried out at a constant temperature of 60°C with IM HNO3 solution, in which 1 ml of IM HNO3 solution was added each time and the eluates were collected. The first 15 samples of eluates were collected by 1 ml at a time and numbered Desorption No. 1 - 15; after that, 5 ml of eluate were collected each time and numbered Desorption No. 16, 21, 26 and 31 respectively. 10 pL of the sample was taken separately to measure the liquid scintillation counting rate. 4. Finally, the desorption of Pu(IV) was continued with 10 mL of eluent containing 0.5M HNO3 and 0.1M NH20H, and the eluate was collected, and 10 pL of sample was taken to measure the liquid scintillation count rate. 5. [Fig. 1] shows the variation curve of the count rate at different stages after the plutonium re-extraction solution has passed through a column. It can be seen that, in the column loading stage, the count rate of the eluate is low and negligible; in the transformation stage, a very small amount of plutonium has passed through the first two column volumes, due to the insufficient nitric acid concentration in the process of increasing the nitric acid concentration in the exchange column to 7.5 mol / L. The problem can be solved by adjusting the eluate to 7.5 mol / L HNO3 and passing it through the column again.In a desorption step using an eluent containing 1M HNO3 and in a desorption step using an eluent containing 0.5M HNO3 and 0.1M NH20H, the plutonium count rate was 99.5% of the total count rate, indicating that more than 99% of the plutonium in the reextraction solution was efficiently recovered by this method.
[0055] Comparative Example 1
[0056] 1.0 mL of the residual organic phase containing plutonium after the deacidification was added to a 15 mL polypropylene centrifuge tube, then 1.0 mL of 0.5 mol / L sodium carbonate solution was added to the centrifuge tube and the mixture was stirred at room temperature for 5 min; after centrifugation at 4000 rpm for 5 min, three phases appeared in the centrifuge tube, and a white emulsion present between the upper organic phase and the lower aqueous phase made the two phases difficult to separate.
[0057] According to the results of the above examples and the above comparative example, it can be seen that the method for treating plutonium contained in the waste organic phase of the PUREX process provided by the present invention can effectively elute the high-content plutonium in the residual organic phase, even the residual organic phase with high plutonium content has been stored for a long time, and more than 99% of the plutonium can be recovered after loading onto the adsorption-transformation-desorption column using the anion exchange column. This method has good application prospects in the elution and recovery of plutonium contained in the residual organic phase with high plutonium content of the spent fuel post-treatment process.
[0058] The preferred embodiments of the present invention have been described in detail above with reference to the attached figure. However, the present invention is not limited to the specific details of the embodiments mentioned above. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the invention. These simple modifications all fall within the scope of protection of the invention.
[0059] Furthermore, it should be noted that the various specific technical features described in the specific embodiments mentioned above may be combined in any suitable manner unless they are incompatible. In order to avoid unnecessary repetition, the present disclosure does not separately explain the various possible combinations.
[0060] In addition, the various embodiments of the present invention can also be arbitrarily combined, as long as they do not violate the spirit of the present invention, they should also be regarded as the contents disclosed in the present disclosure.
Claims
Claims
1. A method of treating plutonium retained in the residual organic phase of the PUREX process, the residual organic phase of the PUREX process containing an organic solvent and plutonium, the method comprising: contacting the residual organic phase of the PUREX process with an aqueous phase re-extraction solution to perform re-extraction, in order to obtain a re-extraction product, characterized in that the aqueous phase re-extraction solution contains 2,6-pyridinedicarboxylic acid, and characterized in that the treatment method further comprises, before contacting the residual organic phase of the PUREX process with the aqueous phase re-extraction solution containing 2,6-pyridinedicarboxylic acid, contacting the residual organic phase of the PUREX process with demineralized water and / or an alkaline solution for deacidification.
2. The method of claim 1, wherein the weight ratio of the aqueous phase re-extraction solution containing 2,6-pyridinedicarboxylic acid to the waste organic phase is 1:(1-10); and the content of 2,6-pyridinedicarboxylic acid in the aqueous phase re-extraction solution is 0.1-0.7 wt%.
3. The method of claim 2, wherein the weight ratio of the aqueous phase re-extraction solution containing 2,6-pyridinedicarboxylic acid to the waste organic phase is 1:(1-5); and the content of 2,6-pyridinedicarboxylic acid in the aqueous phase re-extraction solution is 0.3-0.5 wt%.
4. Method according to claim 1, in which the re-extraction is carried out at a temperature between 10 and 40°C, for a duration between 10 and 30 min and at a stirring speed between 400 and 700 rpm.
5. Method according to claim 4, in which the re-extraction is carried out at a temperature between 20 and 30°C, for a duration between 15 and 20 min and at a stirring speed between 500 and 600 rpm.
6. The method of claim 1, further comprising: • S1, contacting the re-extraction product with an anion exchange resin, so that the plutonium in the re-extraction product is adsorbed on the anion exchange resin to obtain a plutonium-adsorbed anion exchange resin; • S2, contacting the plutonium-adsorbed anion exchange resin with a transformation liquid to obtain a transformed plutonium-adsorbed anion exchange resin; • S3, contacting the transformed plutonium-adsorbed anion exchange resin with an eluent to obtain an eluted product.
7. The method of claim 6, wherein step S1 further comprises, prior to contacting the re-extraction product with an anion exchange resin, adjusting the pH of the re-extraction product to a value between 1 and 4.
8. The method of claim 6, wherein the transformation liquid contains 7-8 mol / L of nitric acid; and the eluent comprises between 0.3 and 1.0 mol / L of an aqueous nitric acid solution, or the eluent is an aqueous solution containing between 0.3 and 1.0 mol / L of nitric acid and between 0.05-0.15 mol / L of NH20H.