Method for removing foreign ions in high-level liquid waste by using 3-oxa-glutaramide extraction agent

Abstract

The invention relates to a method for removing impurity ions in high-level liquid waste by using a 3-oxa-glutaramide extractant, which comprises the following steps: mixing and stirring a 3-oxa-glutaramide extractant solution and the high-level liquid waste, carrying out extraction reaction, and removing an organic phase containing the impurity ions to obtain a water phase rich in ruthenium and rhodium ions. Compared with the prior art, the method has the advantages that the impurity ions in the ruthenium and rhodium solution are extracted by using the 3-oxa-pentanediamide extraction agent, so that the separation of ruthenium and rhodium from impurity elements is realized.

Description

Technical Field

[0001] The invention relates to the technical field of spent fuel post-processing, and in particular to a method for removing impurity ions in high-level radioactive waste liquid by using 3-oxoglutaramide extractants. Background Art

[0002] High-level radioactive liquid waste is the raffinate (i.e., lAW waste) produced during the uranium-plutonium co-decontamination cycle during the spent fuel reprocessing process. High-level radioactive liquid waste contains not only the remaining uranium and plutonium, the minor actinide elements neptunium, americium, and curium, but also more than 320 isotopes of nearly 40 fission products produced when nuclear materials fission. Due to their unique properties, the fission products are widely used in the fields of medicine, industry, and agriculture.

[0003] At present, there are four main methods for separating fragmented elements at home and abroad, namely precipitation, ion exchange, extraction chromatography and solvent extraction. The precipitation method was widely used in the early days, but because of its difficulty in solid-liquid separation under strong radioactive conditions, it is an intermittent operation with complex steps and high labor intensity, so this technology is rarely used now. The ion exchange method has the advantages of simple operation process, strong mechanical, thermal and irradiation stability and very significant selectivity for radioactive nuclides. However, the current ion exchange technology at home and abroad has problems such as low adsorption capacity, poor column operation performance and elution difficulties. The extraction chromatography method is to disperse the functional group-containing extractant in the form of tiny droplets into the polymer carrier, and efficiently separate the component ions from the mixed solution, combining the high selectivity of liquid-liquid extraction and the high efficiency of ion exchange. However, the main problems of the application of extraction chromatography technology under high radioactive conditions are similar to those of ion exchange columns, such as continuous operation, exchange agent unloading, resin treatment and disposal problems, etc. At the same time, some new problems may be added, such as the influence of the extractant radiolysis products, especially the radiolysis gas products, on the operation of the exchange column. The solvent extraction method has the advantages of high productivity, high recovery rate, low production cost, simple operation, and easy long-distance continuous operation. It is easy to realize continuous automated operation for industrial applications and is widely used in the post-processing field.

[0004] The d electron orbitals of platinum group metals are not filled, and the surface is easy to adsorb reactants with moderate strength, which is conducive to the formation of intermediate active compounds. They have high catalytic activity and comprehensive excellent properties such as high temperature resistance, oxidation resistance, and corrosion resistance. They can be used as important catalytic active component materials and are widely used in fine chemicals (including medicine, liquid crystal materials, pesticides, food and feed additives, special chemicals, etc.), basic chemicals, environmental protection, and new energy. Ruthenium and rhodium are a type of fragmentation products in high-level radioactive waste liquid, and their content is objective, comparable to natural resources. In the high-level radioactive waste liquid of the nitric acid system, the morphology and species distribution of ruthenium and rhodium are complex, and they can exist in various valence states (0-8) and can form various complexes with different ligands. In the process of extracting and separating ruthenium and rhodium from radioactive liquid using solvent extraction, acid adjustment and price adjustment are required to ensure the extraction efficiency. Due to the complex composition of high-level radioactive waste liquid, emulsification is easily generated during the acid adjustment and price adjustment process to form a third phase, making the extraction process difficult. Secondly, the presence of other impurity ions will affect the purity of ruthenium and rhodium product solutions.

[0005] Therefore, there is an urgent need to develop a simple and effective method to remove impurity ions in ruthenium and rhodium solutions. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a method for removing impurity ions in high-level waste liquid using 3-oxoglutaramide-type extractants. The impurity ions in ruthenium and rhodium solutions are extracted using 3-oxoglutaramide-type extractants, thereby achieving the separation of ruthenium and rhodium from impurity elements.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] A method for removing impurity ions in high-level radioactive waste liquid by using 3-oxoglutaramide extractants, wherein a 3-oxoglutaramide extractant solution is mixed with the high-level radioactive waste liquid and stirred to perform an extraction reaction, and an organic phase containing impurity ions is removed to obtain an aqueous phase rich in ruthenium and rhodium ions.

[0009] Furthermore, the high-level radioactive liquid waste includes ruthenium, rhodium and impurity elements, and the impurity elements include palladium (Pd), iron (Fe), strontium (Sr), yttrium (Y), zirconium (Zr), molybdenum (Mo), cesium (Cs), barium (Ba), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd) or rhenium (Re).

[0010] Furthermore, the total concentration of ruthenium and rhodium in the high-level radioactive waste liquid is 0.001-1.0 g / L.

[0011] Furthermore, the concentration ratio of ruthenium to rhodium in the high-level radioactive waste liquid is 1:0.001-1000.

[0012] Furthermore, the total concentration of impurity elements in the high-level radioactive waste liquid is 0.01-5 g / L.

[0013] Furthermore, the acidity of the high-level radioactive waste liquid is 1 to 6 mol / L.

[0014] Furthermore, the 3-oxoglutaramide extractant in the 3-oxoglutaramide extractant solution includes N,N,N',N'-tetrapentyl-3-oxoglutaramide, N,N,N',N'-tetrahexyl-3-oxoglutaramide, N,N,N',N'-tetraheptyl-3-oxoglutaramide, N,N,N',N'-tetraoctyl-3-oxoglutaramide, N,N,N',N'-tetranonyl-3-oxoglutaramide, N,N,N',N'-tetradecyl-3-oxoglutaramide, N,N, N',N'-tetrakis-(2-ethylpentyl)-3-oxoglutaramide, N,N,N',N'-tetrakis-(2-ethylhexyl)-3-oxoglutaramide, N,N,N',N'-tetrakis-(2-ethylheptyl)-3-oxoglutaramide, N,N,N',N'-tetrakis-(2-ethyloctyl)-3-oxoglutaramide, N,N,N',N'-tetrakis-(2-ethylnonyl)-3-oxoglutaramide or N,N,N',N'-tetrakis-(2-ethyldecyl)-3-oxoglutaramide.

[0015] Furthermore, the concentration of the 3-oxoglutaramide extractant in the 3-oxoglutaramide extractant solution is 0.01 to 2 mol / L.

[0016] Furthermore, the solvent in the 3-oxoglutaramide extractant solution includes dodecane, ethyl acetate, trimethylbenzene, n-hexanol, n-octanol, isodecanol, tributyl phosphate or kerosene.

[0017] Furthermore, the volume ratio of the high-level radioactive waste liquid to the 3-oxoglutaramide extractant solution is 1:1-3.

[0018] Furthermore, the stirring time is 5 to 60 minutes.

[0019] Furthermore, the extraction reaction is performed 1 to 5 times.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) The present invention uses a solvent extraction method, and utilizes 3-oxoglutaramide extractants to coordinate and complex only with impurity ions, and basically does not coordinate with ruthenium and rhodium. By adjusting the acidity of the high-level waste liquid, the phase ratio, the type and concentration of the 3-oxoglutaramide extractant, and the type of organic solvent, most of the impurity ions in the ruthenium and rhodium feed liquid can be removed. The formation of three phases and precipitation in the subsequent acid adjustment and price adjustment process of the high-level waste liquid is avoided, and the purity of the ruthenium and rhodium product liquid is also guaranteed.

[0022] (2) The operation method of the present invention is simple, convenient and feasible, and can meet the requirements of removing impurity ions in ruthenium and rhodium slurries, and has broad application prospects in the process of extracting ruthenium and rhodium from high-level waste liquid. DETAILED DESCRIPTION

[0025] Example 1

[0026] A method for removing impurity ions in high-level radioactive waste liquid using a 3-oxoglutaramide extractant. In this embodiment, the high-level radioactive waste liquid is simulated high-level radioactive waste liquid. The method comprises the following steps:

[0027] (1) Preparation of simulated high-level radioactive waste: 1 mol / L nitric acid solution was used to prepare 1.0 g / L nitrosyl ruthenium nitrate, 0.29 g / L rhodium nitrate, 0.16 g / L palladium nitrate, 0.11 g / L iron nitrate, 0.18 g / L strontium nitrate, 0.23 g / L yttrium nitrate hexahydrate, 0.34 g / L zirconium nitrate, 0.37 g / L molybdenum nitrate, 0.23 g / L The mixture comprises 0.04 g / L of europium nitrate, 0.04 g / L of gadolinium nitrate hexahydrate and 0.01 g / L of rhenium nitrate.

[0028] (2) Extraction of impurity ions: The prepared simulated high-level radioactive waste liquid was mixed with an equal volume of 0.01 mol / L N,N,N',N'-tetrapentyl-3-oxoglutaramide-n-octanol solution, stirred or shaken for 5 min, and centrifuged at high speed for 5 min. The organic phase containing impurity ions was removed to obtain an aqueous phase rich in ruthenium and rhodium ions.

[0029] (3) Step (2) was repeated 4 more times, and an appropriate amount of aqueous phase was taken for dilution and then ICP-MS test was performed to obtain the extraction rate of each element.

[0030] Example 2

[0031] A method for removing impurity ions in high-level radioactive waste liquid using a 3-oxoglutaramide extractant. In this embodiment, the high-level radioactive waste liquid is simulated high-level radioactive waste liquid. The method comprises the following steps:

[0032] (1) Preparation of simulated high-level radioactive waste: 5 mol / L nitric acid solution was used to prepare 0.44 g / L nitrosyl ruthenium nitrate, 0.001 g / L rhodium nitrate, 0.23 g / L palladium nitrate, 0.19 g / L iron nitrate, 0.15 g / L strontium nitrate, 0.53 g / L yttrium nitrate hexahydrate, 0.64 g / L zirconium nitrate, 0.77 g / L molybdenum nitrate, and 0.33 g / L tantalum nitrate. The invention discloses a mixed liquid of 0.1 g / L cesium nitrate, 0.13 g / L barium nitrate, 0.25 g / L lanthanum nitrate hexahydrate, 0.36 g / L cerium nitrate hexahydrate, 0.44 g / L praseodymium nitrate hexahydrate, 0.75 g / L neodymium nitrate hexahydrate, 0.24 g / L samarium nitrate hexahydrate, 0.12 g / L europium nitrate, 0.15 g / L gadolinium nitrate hexahydrate and 0.36 g / L rhenium nitrate.

[0033] (2) Extraction of impurity ions: The prepared simulated high-level radioactive waste liquid was mixed with 3 volumes of 2.0 mol / L N,N,N',N'-tetradecyl-3-oxoglutaramide-trimethylbenzene-isodecyl alcohol solution, stirred or shaken for 60 min, and centrifuged at high speed for 5 min. The organic phase containing impurity ions was removed to obtain an aqueous phase rich in ruthenium and rhodium ions.

[0034] (3) Step (2) was repeated once more, and an appropriate amount of aqueous phase was taken for dilution and then ICP-MS test was performed to obtain the extraction rate of each element.

[0035] Example 3

[0036] A method for removing impurity ions in high-level radioactive waste liquid using a 3-oxoglutaramide extractant. In this embodiment, the high-level radioactive waste liquid is simulated high-level radioactive waste liquid. The method comprises the following steps:

[0037] (1) Preparation of simulated high-level radioactive waste: 3 mol / L nitric acid solution was used to prepare 0.37 g / L nitrosyl ruthenium nitrate, 0.55 g / L rhodium nitrate, 0.45 g / L palladium nitrate, 0.34 g / L iron nitrate, 0.26 g / L strontium nitrate, 0.47 g / L yttrium nitrate hexahydrate, 0.79 g / L zirconium nitrate, 0.86 g / L molybdenum nitrate, 0.41 g / L The mixed liquid is 0.24 g / L of cesium nitrate, 0.35 g / L of lanthanum nitrate hexahydrate, 0.26 g / L of cerium nitrate hexahydrate, 0.36 g / L of praseodymium nitrate hexahydrate, 0.68 g / L of neodymium nitrate hexahydrate, 0.33 g / L of samarium nitrate hexahydrate, 0.15 g / L of europium nitrate, 0.21 g / L of gadolinium nitrate hexahydrate and 0.27 g / L of rhenium nitrate.

[0038] (2) Extraction of impurity ions: The prepared simulated high-level radioactive waste liquid was mixed with 2 volumes of 1.0 mol / L N,N,N',N'-tetra-(2-ethylhexyl)-3-oxoglutaramide-dodecane-tributyl phosphate solution, stirred or shaken for 30 min, and centrifuged at high speed for 5 min. The organic phase containing impurity ions was removed to obtain an aqueous phase rich in ruthenium and rhodium ions.

[0039] (3) Take an appropriate amount of water phase for dilution and perform ICP-MS test to obtain the extraction rate of each element.

[0040] Example 4

[0041] A method for removing impurity ions in high-level radioactive waste liquid using a 3-oxoglutaramide extractant. In this embodiment, the high-level radioactive waste liquid is simulated high-level radioactive waste liquid. The method comprises the following steps:

[0042] (1) Preparation of simulated high-level radioactive waste: 6 mol / L nitric acid solution containing 0.41 g / L nitrosyl ruthenium nitrate, 0.47 g / L rhodium nitrate, 0.32 g / L palladium nitrate, 0.56 g / L iron nitrate, 0.55 g / L strontium nitrate, 0.34 g / L yttrium nitrate hexahydrate, 0.53 g / L zirconium nitrate, 0.47 g / L molybdenum nitrate, 0.32 g / L The mixed liquid is 0.24 g / L of europium nitrate, 0.31 g / L of gadolinium nitrate hexahydrate and 0.28 g / L of rhenium nitrate.

[0043] (2) Extraction of impurity ions: The prepared simulated high-level radioactive waste liquid was mixed with an equal volume of 0.3 mol / L N,N,N',N'-tetrakis-(2-ethylnonyl)-3-oxoglutaramide-ethyl acetate solution, stirred or shaken for 15 min, and centrifuged at high speed for 5 min. The organic phase containing impurity ions was removed to obtain an aqueous phase rich in ruthenium and rhodium ions.

[0044] (3) Step (2) was repeated three times, and an appropriate amount of aqueous phase was taken for dilution and then ICP-MS test was performed to obtain the extraction rate of each element.

[0045] Comparative Example 1

[0046] Compared with Example 1, most of the steps are the same, except that in step (2), the prepared simulated high-level radioactive waste liquid is mixed with an equal volume of n-octanol.

[0047] Comparative Example 2

[0048] Compared with Example 3, most of the steps are the same, except that in step (2), the prepared simulated high-level radioactive waste liquid is mixed with 2 volumes of dodecane-tributyl phosphate.

[0049] The experimental parameters and test results of Examples 1 to 4 and Comparative Examples 1 and 2 are shown in Table 1.

[0050] Table 1 Experimental parameters and test results of Examples 1 to 4 and Comparative Examples 1 and 2

[0051]

[0052]

[0053] As shown in Table 1, when the 3-oxoglutaramide extractant solution is not used, the extraction rates of the impurity elements Pd, Fe, Sr, Y, Zr, Mo, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd and Re are all less than 0.7%. After the ruthenium and rhodium solutions are extracted using the 3-oxoglutaramide extractant solution, the loss rate of ruthenium is less than 7.1%, the loss rate of rhodium is less than 1.3%, and the extraction rates of the impurity elements Pd, Y, Zr, La, Ce, Pr, Nd, Sm, Eu, and Gd are all greater than 91%, the extraction rates of the impurity elements Mo, Re, and Fe are all greater than 79%, and the extraction rate of the impurity element Sr is greater than 35%. Although the extraction rates of Cs and Ba are less than 2.6%, the 3-oxoglutaramide extractant can remove most of the easily hydrolyzed impurity ions, avoiding the formation of three phases and precipitation in the subsequent acid adjustment and price adjustment process of the feed solution, and also ensuring the purity of the ruthenium and rhodium product solutions.

[0054] Although the present invention has been described in detail above by means of general description, specific implementation methods and tests, it is obvious to those skilled in the art that some modifications or improvements may be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A method for removing impurity ions from high-level radioactive waste liquid using a 3-oxoglutaramide extractant, characterized in that: The 3-oxoglutaramide extractant solution is mixed and stirred with the high-level radioactive waste liquid to carry out extraction reaction, and the organic phase containing impurity ions is removed to obtain an aqueous phase rich in ruthenium and rhodium ions.

2. A method for removing impurity ions in high-level waste liquid using 3-oxoglutaramide extractants according to claim 1, characterized in that: The high-level radioactive liquid waste includes ruthenium, rhodium and impurity elements, and the impurity elements include Pd, Fe, Sr, Y, Zr, Mo, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd or Re.

3. The method for removing impurity ions in high-level radioactive waste liquid using 3-oxoglutaramide extractants according to claim 2, characterized in that: The total concentration of ruthenium and rhodium in the high-level radioactive waste liquid is 0.001-1.0 g / L.

4. A method for removing impurity ions in high-level radioactive waste liquid using 3-oxoglutaramide extractants according to claim 2, characterized in that: The concentration ratio of ruthenium to rhodium in the high-level radioactive waste liquid is 1:0.001-1000.

5. The method for removing impurity ions in high-level waste liquid using 3-oxoglutaramide extractants according to claim 2, characterized in that: The total concentration of impurity elements in the high-level radioactive waste liquid is 0.01-5 g / L.

6. The method for removing impurity ions in high-level radioactive waste liquid using 3-oxoglutaramide extractants according to claim 1, characterized in that: The acidity of the high-level radioactive waste liquid is 1 to 6 mol / L.

7. The method for removing impurity ions in high-level waste liquid using 3-oxoglutaramide extractants according to claim 1, characterized in that: The 3-oxoglutaramide extractant in the 3-oxoglutaramide extractant solution includes N,N,N',N'-tetrapentyl-3-oxoglutaramide, N,N,N',N'-tetrahexyl-3-oxoglutaramide, N,N,N',N'-tetraheptyl-3-oxoglutaramide, N,N,N',N'-tetraoctyl-3-oxoglutaramide, N,N,N',N'-tetranonyl-3-oxoglutaramide, N,N,N',N'-tetradec ... ,N'-tetrakis-(2-ethylpentyl)-3-oxoglutaramide, N,N,N',N'-tetrakis-(2-ethylhexyl)-3-oxoglutaramide, N,N,N',N'-tetrakis-(2-ethylheptyl)-3-oxoglutaramide, N,N,N',N'-tetrakis-(2-ethyloctyl)-3-oxoglutaramide, N,N,N',N'-tetrakis-(2-ethylnonyl)-3-oxoglutaramide or N,N,N',N'-tetrakis-(2-ethyldecyl)-3-oxoglutaramide.

8. The method for removing impurity ions in high-level radioactive waste liquid using 3-oxoglutaramide extractants according to claim 1, characterized in that: The concentration of the 3-oxoglutaramide extractant in the 3-oxoglutaramide extractant solution is 0.01-2 mol / L.

9. The method for removing impurity ions in high-level radioactive waste liquid using 3-oxoglutaramide extractants according to claim 1, characterized in that: The solvent in the 3-oxoglutaramide extractant solution includes dodecane, ethyl acetate, trimethylbenzene, n-hexanol, n-octanol, isodecanol, tributyl phosphate or kerosene.

10. The method for removing impurity ions in high-level radioactive waste liquid using 3-oxoglutaramide extractants according to claim 1, characterized in that: The volume ratio of the high-level radioactive waste liquid to the 3-oxoglutaramide extractant solution is 1:1-3.

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