CN112851573B - Method for recovering technetium from nuclear fuel post-treatment waste liquid - Google Patents
Method for recovering technetium from nuclear fuel post-treatment waste liquid Download PDFInfo
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- CN112851573B CN112851573B CN202011565489.9A CN202011565489A CN112851573B CN 112851573 B CN112851573 B CN 112851573B CN 202011565489 A CN202011565489 A CN 202011565489A CN 112851573 B CN112851573 B CN 112851573B
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D213/00—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members
- C07D213/02—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members
- C07D213/04—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom
- C07D213/06—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom containing only hydrogen and carbon atoms in addition to the ring nitrogen atom
- C07D213/16—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom containing only hydrogen and carbon atoms in addition to the ring nitrogen atom containing only one pyridine ring
- C07D213/20—Quaternary compounds thereof
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G99/00—Subject matter not provided for in other groups of this subclass
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
- G21F9/04—Treating liquids
- G21F9/06—Processing
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
- G21F9/04—Treating liquids
- G21F9/20—Disposal of liquid waste
Abstract
The invention belongs to the technical field of spent fuel post-treatment, and relates to a method for recovering technetium from nuclear fuel post-treatment waste liquid. The method sequentially comprises the following steps: (1) carrying out denitration treatment and concentration treatment on the nitric acid waste liquid containing technetium; (2) adding a solution of polyphenyl pyridine nitrate for precipitation treatment; (3) stirring, aging and filtering the precipitate liquid to obtain a filter cake containing technetium. The method for recovering technetium from the nuclear fuel post-treatment waste liquid can selectively precipitate pertechnetate anion (TcO) from the nuclear fuel post-treatment waste liquid by adopting a large cation precipitation method4 ‑) So as to obtain a purer technetium product, thereby greatly simplifying the extraction process of the technetium.
Description
Technical Field
The invention belongs to the technical field of spent fuel post-treatment, and relates to a method for recovering technetium from nuclear fuel post-treatment waste liquid.
Background
Technetium-99 is a long-life fission product with high yield in nuclear reactors, fission yield of about 6%, half-life of about 2.11X 105And (5) year. Technetium-99 is highly migratory, and in radioactive waste geology, technetium-99 can migrate from the vitreous humor into the ground water, with potential long-term radiation hazard risks to the biosphere. The safest disposal of technetium-99 is to extract it from the radioactive spent liquor of nuclear fuel reprocessing, transmutation by thermal neutrons into stable or short-lived ruthenium elements, bySeparation-transmutation can completely eliminate the harm.
Technetium-99 extraction from post-processing procedures there are several classes of reported or applied patents:
(1) UREX + procedures proposed in the united states, PUREX procedures proposed for the separation of technetium by liu square, etc. The method adopts hydroxamic acid as a key reagent, greatly changes the framework of the post-treatment main process flow, and is not suitable for the traditional PUREX flow post-treatment factory.
(2) Ion exchange method. The post-treatment waste liquid has high technetium concentration, complex waste liquid composition and trace organic reagent degradation products, and is not suitable for an ion exchange method. The ion exchange method is only suitable for trapping technetium with low concentration, and the degradation products of the organic reagent easily affect the service life of the ion exchanger. Meanwhile, the ion exchanger generates a large amount of radioactive solid waste after being discharged, which is not beneficial to minimizing the radioactive waste.
(3) Extracting with trioctylamine, N235, Aliquat336, pyridine and its derivatives, butanone, etc. The extraction method needs multiple extraction, washing and back extraction processes, and can realize high recovery rate of technetium and purification factors, but the process is complicated, and more aqueous phase and organic phase radioactive waste liquid can be generated.
Disclosure of Invention
The object of the present invention is to provide a method for recovering technetium from a nuclear fuel reprocessing waste liquid, so as to enable selective precipitation of pertechnetate anion (TcO) from the nuclear fuel reprocessing waste liquid by a large cation precipitation method4 -) So as to obtain a purer technetium product, thereby greatly simplifying the extraction process of the technetium.
To achieve this object, in a basic embodiment, the present invention provides a method for recovering technetium from a nuclear fuel reprocessing waste stream, said method comprising the steps of, in order:
(1) carrying out denitration treatment and concentration treatment on the nitric acid waste liquid containing technetium;
(2) adding a solution of polyphenyl pyridine nitrate for precipitation treatment;
(3) stirring, aging and filtering the precipitate liquid to obtain a filter cake containing technetium.
The relevant principle of the invention is as follows:
(1) polyphenyl pyridine nitrate is used as a precipitator (tetraphenyl pyridine nitrate is taken as an example, and the structure is shown as the following formula (I)). Polyphenylpyridinium cations are large cations, and precipitate easily with larger anions such as pertechnetate, but do not react with the cations. The impurity ions to be separated during technetium extraction are mainly Uranium (UO)2 2+) Plutonium (Pu)4 +) Strontium (Sr)2+) Cesium (Cs)+) Zirconium (Zr)4+) Ruthenium (RuNO)3+) And, etc., are present as cations under low acid conditions, and these impurity ions do not enter precipitation when large cations are used to precipitate pertechnetate anions. Thus, with this method, selective extraction and purification of technetium can be achieved by one precipitation step.
Precipitation reaction formula of tetraphenylpyridinium nitrate and pertechnetate
(2) The technetium-containing waste liquid in the post-treatment is a nitric acid medium, and nitrate is used as an anion of a large cation precipitator so as not to introduce other types of anions into the waste liquid.
(3) Tetraphenylpyridine nitrate is exemplified. Tetraphenylpyridine nitrate has low solubility in aqueous solution, and in order to introduce tetraphenylpyridine free cations into technetium-containing waste liquid, tetraphenylpyridine needs to be dissolved in an organic solvent, and then added into a precipitation feed liquid, wherein the organic solvent needs to be mutually soluble with water. The organic solvents such as methanol, ethanol, acetone, dioxane and the like are examined, and the experimental result shows that the solubility of the tetraphenylpyridine nitrate in the methanol is 5.38g/L, and the saturated solution of the tetraphenylpyridine nitrate has the best effect on the precipitation of technetium when the saturated solution is added into the technetium-containing waste liquid of the nitric acid medium, as shown in Table 1.
TABLE 1 precipitation Rate of Tc Using 1:1(v/v) amount of tetraphenylpyridine nitrate in different solvents
| Solvent(s) | Methanol | Ethanol | Acetone (II) | Dioxane (dioxane) |
| Single stage precipitation rate | 0.72 | 0.57 | 0.20 | 0.12 |
(4) Nitrate concentrations at higher levels are detrimental to pertechnetate precipitation. Therefore, the feed liquid is denitrated, concentrated, and precipitated with pertechnetate when the acidity is adjusted to about 0.1mol/L (see tables 2 and 3). The amount of tetraphenylpyridine nitrate is preferably 1.6 times that of technetium.
TABLE 2 precipitation Rate of technetium with 1:1(v/v) amount of tetraphenylpyridine nitrate at different acidity
| Nitric acid concentration (mol/L) | 1 | 0.5 | 0.25 | 0.1 | 0 |
| Rate of precipitation | 0.19 | 0.17 | 0.19 | 0.75 | 0.22 |
TABLE 30.1 mol/L acidity, amount of tetraphenylpyridine nitrate and precipitation rate
In a preferred embodiment, the present invention provides a method for recovering technetium from a nuclear fuel reprocessing waste liquid, wherein in step (1), the denitration treatment is to reduce the concentration of nitric acid in the technetium-containing nitric acid waste liquid to 0.01 to 0.1 mol/L.
In a preferred embodiment, the present invention provides a process for recovering technetium from a nuclear fuel reprocessing waste liquid wherein in step (1) said denitration treatment is formic acid denitration.
In a preferred embodiment, the present invention provides a method for recovering technetium from a nuclear fuel reprocessing waste liquid, wherein in step (1), the concentration treatment is carried out at a volume concentration factor of 20 to 50 times (concentration to a technetium concentration of 4 to 10 g/L).
In a preferred embodiment, the present invention provides a method for recovering technetium from a nuclear fuel reprocessing waste stream, wherein in step (2), said polyphenylpyridine nitrate is 1,2,4, 6-tetraphenylpyridine nitrate.
In a preferred embodiment, the invention provides a method for recovering technetium from a nuclear fuel post-treatment waste liquid, wherein in the step (2), the organic solvent is one or more selected from methanol, ethanol, acetone and dioxane, and the solution of the poly-phenylpyridine nitrate is a saturated organic solvent solution.
In a preferred embodiment, the present invention provides a method for recovering technetium from a nuclear fuel reprocessing waste liquid, wherein in step (2), the molar ratio of technetium in the technetium-containing nitric acid waste liquid after denitration treatment and concentration treatment to the polyphenyl pyridine nitrate is 1: 1.6-2.5.
In a preferred embodiment, the invention provides a method for recovering technetium from a nuclear fuel post-treatment waste liquid, wherein in the step (3), the stirring rotation speed of the stirring treatment is 50-200r/min, and the time is 1-5 min.
In a preferred embodiment, the present invention provides a method for recovering technetium from a nuclear fuel reprocessing waste liquid, wherein in step (3), the aging time is 10 to 20 min.
In a preferred embodiment, the present invention provides a method for recovering technetium from a nuclear fuel reprocessing waste liquid, wherein in step (3), the filtrate obtained by said filtration treatment is further subjected to a middle-emission waste liquid treatment.
The method for recovering technetium from the nuclear fuel post-treatment waste liquid has the advantages that the large cation precipitation method can be adopted to selectively precipitate pertechnetate anion (TcO) from the nuclear fuel post-treatment waste liquid4 -) So as to obtain a purer technetium product, thereby greatly simplifying the extraction process of the technetium.
Technetium mainly exists in the radioactive waste liquid of Purex process, and mainly exists as pertechnetate anion, and other impurity ions, such as uranium, plutonium, strontium, cesium, zirconium, ruthenium and the like, basically exist as cations. The invention adopts a method of selective precipitation of anions, realizes selective extraction and purification of technetium through one precipitation step, and decontaminates uranium, plutonium and other lobe elements, thereby simplifying the technetium extraction process.
Detailed Description
The following examples further illustrate specific embodiments of the present invention.
Example 1: synthesis of 1,2,4, 6-tetraphenylpyridine nitrate
The synthesis principle of this example is as follows:
(1) synthesis of 2,4, 6-triphenyl pyran perchlorate
Adding 2mmol of acetophenone and 1mmol of benzaldehyde into a 200ml reaction bottle, heating to 110 ℃, adding 1.5mmol of excessive perchloric acid, and continuing to stir at 1500r/min for reaction for 30 min. After the reaction, the reaction mixture was cooled to 20 ℃ and 3ml of acetone was added, followed by addition of ether to precipitate the desired product.
(2) Synthesis of 1,3, 5-triphenyl-2-pentan-1, 5-dione
10mmol of 2,4, 6-triphenylpyran perchlorate is added to boiling 200ml of 95% (v/v) ethanol; adding 50ml of aqueous solution of sodium acetate (40mmol) under the condition of vigorous stirring (2000r/min), immediately precipitating a solid product after a reaction system is clarified, freezing and standing at 0 ℃ for 10 hours after the reaction is finished for 3 hours, and recrystallizing the obtained solid by ethanol.
(3) Synthesis of 2,4, 6-triphenylpyran nitrate
10mmol of 1,3, 5-triphenyl-2-pentan-1, 5-dione are dissolved in 40ml of boiling 95% (v/v) ethanol, the mixture is quickly stirred (1500r/min) after being dissolved, excess nitric acid is added, and crystals are precipitated after cooling to 0 ℃. (4) Synthesis of 1,2,4, 6-tetraphenylpyridine nitrate
2mmol of 2,4, 6-triphenyl pyran nitrate and 2.2mmol of aniline are added into 30ml of absolute ethyl alcohol, and the reflux reaction is carried out for 5 hours until the system is clear. After the reaction is finished, the mixture is cooled to room temperature, then concentrated to 3ml, and then 20ml of n-hexane is added to obtain the product 1,2,4, 6-tetraphenylpyridine nitrate with the purity of 99% (based on nuclear magnetism) and the yield of 90% (based on acetophenone).
Example 2: recovery of technetium from spent nuclear fuel reprocessing effluents
Technetium was recovered from a nuclear fuel reprocessing waste liquid using 1,2,4, 6-tetraphenylpyridine nitrate obtained in example 1 as follows.
(1) The waste liquid containing technetium and nitric acid in plutonium purification circulation generated in a post-treatment plant (the content of technetium is 0.1g/L) is denitrated (the denitration is carried out at the temperature of more than 90 ℃ by adopting formic acid), the concentration of nitric acid is reduced to 0.1mol/L, and the concentration is about 40 times.
(2)1, 2,4, 6-tetraphenylpyridine nitrate was dissolved in methanol to obtain a saturated solution. Adding a methanol saturated solution of 1,2,4, 6-tetraphenylpyridine nitrate into the technetium-containing radioactive waste solution evaporated and concentrated in the step (1) according to the using amount of 1.6:1 of the precipitant 1,2,4, 6-tetraphenylpyridine nitrate and technetium in a molar ratio of 1.6:1 to perform precipitation treatment.
(3) Stirring the precipitation solution for 5 minutes, aging for 15 minutes, and filtering to obtain a filter cake containing technetium (the recovery rate of technetium is above 96%, and the decontamination factor for cationic impurities such as strontium, cesium, zirconium, ruthenium and the like is above 100%).
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations. The foregoing examples or embodiments are merely illustrative of the present invention, which may be embodied in other specific forms or in other specific forms without departing from the spirit or essential characteristics thereof. The described embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. The scope of the invention should be indicated by the appended claims, and any changes that are equivalent to the intent and scope of the claims should be construed to be included therein.
Claims (6)
1. A method for recovering technetium from a nuclear fuel reprocessing waste stream, said method comprising the steps of:
(1) carrying out denitration treatment and concentration treatment on the nitric acid waste liquid containing technetium;
(2) adding a solution of polyphenyl pyridine nitrate for precipitation treatment;
(3) stirring, aging and filtering the precipitate liquid to obtain a filter cake containing technetium,
wherein:
in the step (1), the denitration treatment is to reduce the concentration of nitric acid in the nitric acid waste liquid containing technetium to 0.01-0.1 mol/L;
in the step (2), the polyphenyl pyridine nitrate is 1,2,4, 6-tetraphenyl pyridine nitrate;
in the step (2), the solution of the poly-phenylpyridine nitrate is a saturated organic solvent solution, and the organic solvent is methanol;
in the step (2), the molar ratio of the technetium in the nitric acid waste liquid containing technetium after denitration treatment and concentration treatment to the poly-phenylpyridine nitrate is 1: 1.6-2.5.
2. The method of claim 1, wherein: in the step (1), the denitration treatment is formic acid denitration.
3. The method of claim 1, wherein: in the step (1), the volume concentration multiple of the concentration treatment is 20-50 times.
4. The method of claim 1, wherein: in the step (3), the stirring speed of the stirring treatment is 50-200r/min, and the time is 1-5 min.
5. The method of claim 1, wherein: in the step (3), the aging treatment time is 10-20 min.
6. The method of claim 1, wherein: and (4) in the step (3), performing middle-level radioactive liquid waste treatment on the filtrate obtained by the filtration treatment.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4654173A (en) * | 1985-11-21 | 1987-03-31 | Walker Darrel D | Nuclear waste solutions |
| CN106732481A (en) * | 2017-01-10 | 2017-05-31 | 苏州大学 | A kind of pertechnetate adsorbent and its synthetic method and the application in radioactive wastewater is processed |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4654173A (en) * | 1985-11-21 | 1987-03-31 | Walker Darrel D | Nuclear waste solutions |
| CN106732481A (en) * | 2017-01-10 | 2017-05-31 | 苏州大学 | A kind of pertechnetate adsorbent and its synthetic method and the application in radioactive wastewater is processed |
Non-Patent Citations (3)
| Title |
|---|
| 1,2,4,6-Tetraphenylpyridinium acetate as a new anion precipitant;Thomas C.Chadwick;《ANALYTICAL CHEMISTRY》;19761231;第48卷(第8期);第1201-1202页 * |
| Tetraphenylpyridinium pertechnetate: a promising salt for the immobilization of technetium;Edward Mausolf.et al;《Radiochimica Acta》;20121231;第325–328页"第325页右栏第2段，第325-326跨页段2.2节，以及第326页第3.1节" * |
| 面向核废料处理和环境去污的99TcO4-分离进展;梅雷等;《中国科学基金》;20191231;第592-600页 * |
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