Method for regenerating waste organic phase in lanthanum actinide separation process

Abstract

The invention relates to a method for regenerating a waste organic phase in a lanthanum actinide separation process, and particularly relates to a method for optimizing a waste organic phase regeneration reagent NaOH solution in an original process into a nitric acid solution of oxygen glutardiamide aiming at a waste organic phase regeneration operation unit in an LACOS process. Comprising the following steps: S1, preparing a pentanediamide solution with set acidity; s2, taking the reagent prepared in the S1 as a washing liquid, mixing the washing liquid with a waste organic phase according to a set phase ratio, stirring under a set temperature condition, performing centrifugal phase separation, and collecting washing waste liquid and a washed organic phase; and then measuring the content of lanthanide in the washing waste liquid, calculating the content of lanthanide in the washed organic phase, and evaluating the regeneration effect of the waste organic phase. Compared with the prior art, the method has the advantages of simple regeneration process, low reagent cost, good regeneration effect and the like.

Description

Technical Field

[0001] The invention relates to the field of nuclear fuel cycle, in particular to a method for regenerating a waste organic phase in a lanthanum-actinium separation process. Background Art

[0002] After the spent fuel is processed in the reprocessing facility, a large amount of high-level waste liquid is generated. In order to reduce the alpha radioactivity in the high-level waste liquid, the lanthanum-actinium separation process is used to recover the alpha nuclides. The LACOS process ( Figure 1 ) consists of lanthanum and actinium co-extraction, lanthanum and actinium washing, actinide stripping, lanthanide supplementary extraction, oil removal, evaporation concentration and organic phase regeneration (NaOH alkaline washing) units. The waste organic phase of this process contains a large amount of lanthanide elements. The waste organic phase of this process is washed with NaOH alkaline, and three phases are produced during the regeneration process, resulting in the inability of the organic phase regeneration operation unit to operate continuously in the mixing and settling tank. Considering the economic efficiency of the actual operation of the process and the cost of the extractant, it is necessary to find an effective method to regenerate the waste organic phase of the lanthanum and actinium separation process.

[0003] At present, there are mainly acid washing, alkaline washing, adsorption and other methods for the regeneration of waste organic phase. Patent CN112063838A discloses a method for purifying and regenerating waste organic phase containing P204 (HDEHP) and P507 (HEH [EHP]) extractants. First, the waste organic phase is washed with high concentration (6-8 mol / L) hydrochloric acid, and then washed with 10% oxalic acid. Then, acidified activated clay is added to the washed organic phase as a treatment agent to adsorb impurity metals and high polar molecules. Subsequently, the activated clay is removed by filter pressing to obtain a clear organic phase. Patent CN110950905A uses strontium oxide as a precipitant, and purifies the waste organic phase by three steps of acid washing, precipitation and regeneration, and recovers the extractant HEH [EHP] with a yield of 90-92%. Patent CN104131163A uses a hot sodium hydroxide solution at a temperature of 90-100°C to treat an organic phase emulsion containing HEH[EHP]. Through the synergistic effect of physical heat energy and sodium hydroxide, the emulsified HEH[EHP] organic phase is regenerated with a recovery rate of more than 99%, and the rare earth elements in the organic phase are recovered at the same time.

[0004] The acid washing and adsorption methods for regenerating the waste organic phase are cumbersome, time-consuming and energy-intensive, while the alkaline washing method has also been proven in the LACOS process to easily produce three phases, resulting in the inability of the washing process to operate continuously in the mixing and settling tank and serious entrainment of the aqueous and organic phases. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a method for regenerating the waste organic phase in the lanthanum-actinium separation process, wherein the waste organic phase is washed with a nitric acid solution containing oxyglutaramide, and the washed organic phase meets the reuse requirements. The method has the advantages of simple operation, low energy consumption and low cost, and is suitable for treating industrial-scale waste organic phase.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] The present invention provides a method for regenerating a waste organic phase in a lanthanum-actinium separation process, comprising the following steps:

[0008] S1: prepare oxyglutaramide solution with set acidity;

[0009] S2: The reagent prepared in S1 is used as a washing liquid, mixed with the waste organic phase according to a set ratio, stirred under set temperature conditions, centrifuged to separate the phases, and the organic phase is collected; then the content of lanthanide elements in the washing waste liquid is determined, the content of lanthanide elements in the organic phase after washing is calculated, and the regeneration effect of the waste organic phase is evaluated.

[0010] Furthermore, in the structural formula of oxyglutaramide used in S1, R 1 , R 2 , R 3 and R 4 is a straight chain alkyl or a branched chain alkyl, the number of carbon atoms in the alkyl is ≤ 4, and R 1 , R 2 , R 3 and R 4 It cannot be a C4 alkyl group at the same time.

[0011] Furthermore, in S1, the concentration of oxyglutaramide is 0.05-1.0 mol / L, and the acidity of the washing liquid is 0.01-1.0 mol / L.

[0012] Furthermore, in S2, the waste organic phase comprises: an extractant, a co-extractant, a diluent, and lanthanide elements.

[0013] Furthermore, the extractant is T2EHDGA (N,N,N',N'-tetra(2-ethylhexyl)-3-oxaglutaramide) or TODGA (N,N,N',N'-tetraoctyl-3-oxaglutaramide), the synergist is HDEHP (di(2-ethylhexyl) phosphate) or HEH[EHP] (2-ethylhexylphosphonic acid mono-2-ethylhexyl ester), and the diluent is kerosene or n-dodecane.

[0014] Furthermore, the type of lanthanide elements is one or more of the lanthanide elements La-Lu, and the content of the lanthanide elements is 0.01-5.0 g / L.

[0015] Further, the ratio of the reagent prepared in S1 to the waste organic phase is 1.0-3.0.

[0016] Furthermore, in S2, the washing temperature is from room temperature to 60°C.

[0017] Preferably, the oxyglutaramide is N,N,N',N'-tetraethyl diglycolamide or N,N,N',N'-tetramethyl diglycolamide.

[0018] Furthermore, in S2, the stirring time is 10 min, the phase separation is performed by centrifugation, the centrifugal speed is 3000 r / min, and the centrifugal time is 2 min.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] The present invention provides a new idea for regenerating the waste organic phase in the lanthanum-actinium separation process. The waste organic phase is washed with a nitric acid solution containing oxyglutaramide. The washed organic phase meets the reuse requirements. The present invention has the advantages of simple regeneration process, low reagent cost and good regeneration effect. It not only reduces the investment in waste organic phase storage facilities, but also reduces the use of extractants and saves reagent costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the LACOS process;

[0022] Figure 2 is the structural formula of oxyglutaramide;

[0023] Figure 3 is the structural formula of N,N,N',N'-tetraethyl diglycolamide;

[0024] Figure 4 It is the structural formula of N,N,N',N'-tetramethyl diglycol amide.

[0025] Figure 5 The present invention is a flow chart of a method for regenerating a waste organic phase in a lanthanum-actinium separation process. DETAILED DESCRIPTION

[0026] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms and other features not clearly described in this technical solution are all considered to be common technical features disclosed in the prior art.

[0027] Example 1

[0028] This embodiment provides a method for regenerating the waste organic phase in the lanthanum-actinium separation process, such as Figure 5 As shown, the following steps are included:

[0029] S1: prepare oxyglutaramide solution with set acidity;

[0030] S2: The reagent prepared in S1 is used as a washing liquid, mixed with the waste organic phase according to a set ratio, stirred under set temperature conditions, centrifuged to separate the phases, and the washing waste liquid and the organic phase after washing are collected; then the content of lanthanide elements in the washing waste liquid is determined, the content of lanthanide elements in the organic phase after washing is calculated, and the regeneration effect of the waste organic phase is evaluated.

[0031] In a specific embodiment, the structural formula of oxyglutaramide is as follows Figure 2 As shown, the oxyglutaramide solution used in S1 is a nitric acid solution of N,N,N',N'-tetraethyl diglycolamide, such as Figure 3 shown.

[0032] LACOS process Figure 1 As shown, in the LACOS process, the composition of the waste organic phase is T2EHDGA+HEH[EHP]+n-dodecane+lanthanide elements, and the lanthanide element composition is La: 0.137 g / L, Ce: 0.396 g / L, Pr: 0.265 g / L, Nd: 0.883 g / L, Sm: 0.239 g / L, Eu: 0.073 g / L, and Gd: 0.044 g / L. The waste organic phase was washed with a nitric acid solution of 0.2 mol / L N,N,N',N'-tetraethyl diglycolamide, the nitric acid concentration in the washing solution was 0.2 mol / L, and the phase ratio (aqueous phase / organic phase) was 2; the phase was shaken in a 25°C constant temperature water bath shaker for 10 min, and the shaker shaking frequency was 200 times / min; the phase was separated by centrifugation, the centrifuge speed was 3000r / min, and the centrifugation was performed for 2 min; the organic phase was collected, and the recovery rate of the organic phase was calculated; and 2 mL of the aqueous phase was taken, diluted, and the lanthanide ion concentration was analyzed by ICP-MS. According to calculations, the washing rate of N,N,N',N'-tetraethyl diglycolamide for lanthanide elements is greater than 99.90%, and the recovery rate of the organic phase after washing is 97%, which can be directly used for lanthanum and actinium co-extraction in the extraction stage.

[0033] Example 2

[0034] This embodiment provides a method for regenerating the waste organic phase in the lanthanum-actinium separation process, such as Figure 5 As shown, the following steps are included:

[0035] S1: prepare oxyglutaramide solution with set acidity;

[0036] S2: The reagent prepared in S1 is used as a washing liquid, mixed with the waste organic phase according to a set ratio, stirred under set temperature conditions, centrifuged to separate the phases, and the washing waste liquid and the organic phase after washing are collected; then the content of lanthanide elements in the washing waste liquid is determined, the content of lanthanide elements in the organic phase after washing is calculated, and the regeneration effect of the waste organic phase is evaluated.

[0037] In a specific embodiment, the structural formula of oxyglutaramide is as follows Figure 2 As shown, the oxyglutaramide solution used in S1 is a nitric acid solution of N,N,N',N'-tetraethyl diglycolamide, such as Figure 3 shown.

[0038] LACOS process Figure 1 As shown, in the LACOS process, the composition of the waste organic phase is TODGA + HEH [EHP] + n-dodecane + lanthanide elements, and the lanthanide element composition is La: 0.148 g / L, Ce: 0.375 g / L, Pr: 0.217 g / L, Nd: 0.902 g / L, Sm: 0.197 g / L, Eu: 0.069 g / L, and Gd: 0.052 g / L. The waste organic phase was washed with a nitric acid solution of 0.5 mol / L N,N,N',N'-tetraethyl diglycolamide, the nitric acid concentration in the washing solution was 0.2 mol / L, and the phase ratio (aqueous phase / organic phase) was 2; the phase was shaken in a 25°C constant temperature water bath shaker for 10 minutes, and the shaker shaking frequency was 200 times / min; the phase was separated by centrifugation, the centrifuge speed was 3000r / min, and the centrifugation was performed for 2 minutes; the organic phase was collected, and the recovery rate of the organic phase was calculated; and 2 mL of the aqueous phase was taken, diluted, and the lanthanide ion concentration was analyzed by ICP-MS. According to calculations, the washing rate of N,N,N',N'-tetraethyl diglycolamide for lanthanide elements is greater than 99.50%, and the recovery rate of the organic phase after washing is 99%, which can be directly used for lanthanum and actinium co-extraction in the extraction stage.

[0039] Example 3

[0040] This embodiment provides a method for regenerating the waste organic phase in the lanthanum-actinium separation process, such as Figure 5 As shown, the following steps are included:

[0041] S1: prepare oxyglutaramide solution with set acidity;

[0042] S2: The reagent prepared in S1 is used as a washing liquid, mixed with the waste organic phase according to a set ratio, stirred under set temperature conditions, centrifuged to separate the phases, and the washing waste liquid and the organic phase after washing are collected; then the content of lanthanide elements in the washing waste liquid is determined, the content of lanthanide elements in the organic phase after washing is calculated, and the regeneration effect of the waste organic phase is evaluated.

[0043] In a specific embodiment, the structural formula of oxyglutaramide is as follows Figure 2 As shown, the oxyglutaramide solution used in S1 is a nitric acid solution of N,N,N',N'-tetraethyl diglycolamide, such as Figure 3 shown.

[0044] LACOS process Figure 1As shown, in the LACOS process, the composition of the waste organic phase is T2EHDGA+HDEHP+n-dodecane+lanthanide elements, and the lanthanide element composition is La: 0.132 g / L, Ce: 0.388 g / L, Pr: 0.240 g / L, Nd: 0.957 g / L, Sm: 0.228 g / L, Eu: 0.075 g / L, and Gd: 0.043 g / L. The waste organic phase was washed with 0.2mol / L N,N,N',N'-tetraethyl diglycolamide nitric acid solution, the nitric acid concentration in the washing solution was 0.5mol / L, and the phase ratio (aqueous phase / organic phase) was 2; the phase was shaken in a 25°C constant temperature water bath shaker for 10 minutes, and the shaker shaking frequency was 200 times / min; the phase was separated by centrifugation, the centrifuge speed was 3000r / min, and the centrifugation was performed for 2 minutes; the organic phase was collected, and the recovery rate of the organic phase was calculated; and 2mL of the aqueous phase was taken, diluted, and the lanthanide ion concentration was analyzed by ICP-MS. According to calculations, the washing rate of N,N,N',N'-tetraethyl diglycolamide for lanthanide elements is greater than 99.65%, and the recovery rate of the organic phase after washing is 97%, which can be directly used for lanthanum and actinium co-extraction in the extraction stage.

[0045] Example 4

[0046] This embodiment provides a method for regenerating the waste organic phase in the lanthanum-actinium separation process, such as Figure 5 As shown, the following steps are included:

[0047] S1: prepare oxyglutaramide solution with set acidity;

[0048] S2: The reagent prepared in S1 is used as a washing liquid, mixed with the waste organic phase according to a set ratio, stirred under set temperature conditions, centrifuged to separate the phases, and the washing waste liquid and the organic phase after washing are collected; then the content of lanthanide elements in the washing waste liquid is determined, the content of lanthanide elements in the organic phase after washing is calculated, and the regeneration effect of the waste organic phase is evaluated.

[0049] In a specific embodiment, the structural formula of oxyglutaramide is as follows Figure 2 As shown, the oxyglutaramide solution used in S1 is a nitric acid solution of N,N,N',N'-tetraethyl diglycolamide, such as Figure 3 shown.

[0050] LACOS process Figure 1As shown, in the LACOS process, the composition of the waste organic phase is TODGA+HDEHP+n-dodecane+lanthanide elements, and the lanthanide element composition is La: 0.155 g / L, Ce: 0.394 g / L, Pr: 0.241 g / L, Nd: 0.980 g / L, Sm: 0.225 g / L, Eu: 0.082 g / L, and Gd: 0.060 g / L. The waste organic phase was washed with a nitric acid solution of 0.2 mol / L N,N,N',N'-tetraethyl diglycolamide, the nitric acid concentration in the washing solution was 0.5 mol / L, and the phase ratio (aqueous phase / organic phase) was 2; the mixture was shaken in a 25°C constant temperature water bath shaker for 10 min, and the shaker shaking frequency was 200 times / min; the phases were separated by centrifugation, the centrifuge speed was 3000r / min, and the centrifugation was performed for 2 min; the organic phase was collected, and the recovery rate of the organic phase was calculated; and 2 mL of the aqueous phase was taken, diluted, and the lanthanide ion concentration was analyzed by ICP-MS. According to calculations, the washing rate of N,N,N',N'-tetraethyl diglycolamide for lanthanide elements was greater than 99.87%, and the recovery rate of the organic phase after washing was 98%, which can be directly used for the co-extraction of lanthanum and actinium in the extraction stage.

[0051] Example 5

[0052] This embodiment provides a method for regenerating the waste organic phase in the lanthanum-actinium separation process, such as Figure 5 As shown, the following steps are included:

[0053] S1: prepare oxyglutaramide solution with set acidity;

[0054] S2: The reagent prepared in S1 is used as a washing liquid, mixed with the waste organic phase according to a set ratio, stirred at a set temperature, centrifuged to separate the phases, and the washing waste liquid and the organic phase after washing are collected; then the content of lanthanide elements in the washing waste liquid is determined, the content of lanthanide elements in the organic phase after washing is calculated, and the regeneration effect of the waste organic phase is evaluated. In a specific embodiment, the structural formula of oxyglutaramide is as follows Figure 2 As shown, the oxyglutaramide solution used in S1 is a nitric acid solution of N,N,N',N'-tetramethyl diglycolamide, such as Figure 4 shown.

[0055] LACOS process Figure 1As shown, in the LACOS process, the composition of the waste organic phase is T2EHDGA+HEH[EHP]+n-dodecane+lanthanide elements, and the lanthanide element composition is La: 0.134 g / L, Ce: 0.398 g / L, Pr: 0.260 g / L, Nd: 0.876 g / L, Sm: 0.244 g / L, Eu: 0.070 g / L, and Gd: 0.049 g / L. The waste organic phase was washed with 0.3 mol / L N,N,N',N'-tetramethyl diglycolamide nitric acid solution, the nitric acid concentration in the washing solution was 0.5 mol / L, and the phase ratio (aqueous phase / organic phase) was 2; the phase was shaken in a 25°C constant temperature water bath shaker for 10 minutes, and the shaker shaking frequency was 200 times / min; the phase was separated by centrifugation, the centrifuge speed was 3000r / min, and the centrifugation was performed for 2 minutes; the organic phase was collected, and the recovery rate of the organic phase was calculated; and 2 mL of the aqueous phase was taken, diluted, and the lanthanide ion concentration was analyzed by ICP-MS. According to calculations, the washing rate of N,N,N',N'-tetramethyl diglycolamide for lanthanide elements is greater than 99.60%, and the recovery rate of the organic phase after washing is 95%, which can be directly used for lanthanum and actinium co-extraction in the extraction stage.

[0056] Components not described in detail in this embodiment are all existing components that can be purchased through public channels.

[0057] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for regenerating the waste organic phase in the lanthanum-actinium separation process, specifically for the waste organic phase regeneration operation unit in the LACOS process (see Figure 1), optimizing the waste organic phase regeneration reagent NaOH solution in the original process to a nitric acid solution of glutaramide. It is characterized in that: The following steps are involved: S1: prepare oxyglutaramide solution with set acidity; S2: The reagent prepared in S1 is used as a washing liquid, mixed with the waste organic phase according to a set ratio, stirred at a set temperature, centrifuged to separate the phases, and the washing waste liquid and the washed organic phase are collected; Then the content of lanthanide elements in the washing waste liquid was determined, the content of lanthanide elements in the organic phase after washing was calculated, and the regeneration effect of the waste organic phase was evaluated.

2. The method for regenerating a waste organic phase in a lanthanum-actinium separation process according to claim 1, characterized in that: In the structural formula of oxyglutaramide used in S1, R 1 , R 2 , R 3 and R 4 is a straight chain alkyl or a branched chain alkyl, the number of carbon atoms in the alkyl is ≤ 4, and R 1 , R 2 , R 3 and R 4 It cannot be a C4 alkyl group at the same time.

3. The method for regenerating a waste organic phase in a lanthanum-actinium separation process according to claim 1, characterized in that: In S1, the concentration of oxyglutaramide is 0.05-1.0 mol / L, and the acidity of the washing liquid is 0.01-1.0 mol / L.

4. The method for regenerating a waste organic phase in a lanthanum-actinium separation process according to claim 1, characterized in that: In S2, the waste organic phase comprises: an extractant, a co-extractant, a diluent, and lanthanide elements.

5. The method for regenerating a waste organic phase in a lanthanum-actinium separation process according to claim 4, characterized in that: The extractant is T2EHDGA or TODGA, the synergistic extractant is HDEHP or HEH[EHP], and the diluent is kerosene or n-dodecane.

6. A method for regenerating a waste organic phase in a lanthanum-actinium separation process according to claim 4, characterized in that: The lanthanide element type is one or more of the lanthanide elements La-Lu, and the content of the lanthanide elements is 0.01-5.0 g / L.

7. The method for regenerating a waste organic phase in a lanthanum-actinium separation process according to claim 1, characterized in that: The reagent prepared in S1 has a ratio of 1.0-3.0 to the waste organic phase.

8. The method for regenerating a waste organic phase in a lanthanum-actinium separation process according to claim 1, characterized in that: In S2, the washing temperature is from room temperature to 60°C.

9. The method for regenerating a waste organic phase in a lanthanum-actinium separation process according to claim 1, characterized in that: The oxyglutaramide is N,N,N',N'-tetraethyl diglycolamide or N,N,N',N'-tetramethyl diglycolamide.

10. The method for regenerating a waste organic phase in a lanthanum-actinium separation process according to claim 1, characterized in that: In S2, the stirring time is 10 min, the phases are separated by centrifugation, the centrifugal speed is 3000 r / min, and the centrifugal time is 2 min.

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