A method of regenerating a natural uranium extraction agent

Abstract

The application provides a regeneration method of natural uranium extractant. In the regeneration method of the natural uranium extractant, the natural uranium extractant comprises tributyl phosphate and hydrogenated kerosene, and the regeneration method comprises the following steps which are sequentially performed: S1: washing the natural uranium extractant to be regenerated by using a sodium hydroxide solution, and then acidizing by using a nitric acid solution; S2: washing the natural uranium extractant after the washing and acidizing in step S1 by using a sodium carbonate solution, and then acidizing by using a nitric acid solution to obtain the regenerated natural uranium extractant. The regenerated natural uranium extractant obtained by the regeneration method has good selectivity and stability, and the reuse of the natural uranium extractant is realized.

Description

A method for regenerating natural uranium extractant Technical Field

[0001] This invention relates to the field of natural uranium purification technology, and in particular to a method for regenerating natural uranium extractants. Background Technology

[0002] Currently, uranium purification processes typically employ a "wet" extraction method. This process dissolves solid U3O8 to obtain a uranyl nitrate solution, which is then purified through an extraction-washing-back-extraction process to remove impurity elements. The extraction process usually uses tributyl phosphate (TBP)-hydrogenated kerosene as the extractant to extract uranyl nitrate from the uranyl nitrate-nitric acid aqueous solution into the organic phase, while impurity elements remain in the aqueous phase. The back-extraction process typically uses a dilute nitric acid solution to back-extract uranium from the organic phase into the aqueous phase. The organic phase, as the purification carrier for metallic uranium, significantly affects the quality of the purified product.

[0003] However, as the usage time of TBP (as a uranium extractant) and hydrogenated kerosene (as a diluent) in the extractant increases, the extractant undergoes chain scission, polymerization, hydrolysis, nitration, and oxidation reactions under the influence of radiation, high temperature, and chemical reagents. This results in degradation products such as dibutyl phosphate (DBP), monobutyl phosphate (MBP), and dodecyl acid, as well as other impurities. These not only cause trace amounts of uranium to remain in the extractant, leading to a decrease in the yield of metallic uranium, but also reduce the extraction efficiency during the extraction process, increasing the uranium concentration in the raffinate aqueous phase, which in turn reduces the uranium yield. All of these factors limit the service life of the extractant.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a method for regenerating natural uranium extractant. The regenerated natural uranium extractant obtained by this method has good selectivity and stability, and realizes the reuse of natural uranium extractant.

[0006] This invention provides a method for regenerating a natural uranium extractant (also known as an organic phase), the natural uranium extractant comprising tributyl phosphate and hydrogenated kerosene, and the regeneration method comprising the following steps performed in sequence:

[0007] S1: The natural uranium extractant to be regenerated (also known as the lean organic phase) is washed with sodium hydroxide solution, and then acidified with nitric acid solution;

[0008] S2: The natural uranium extractant after washing and acidification in step S1 is washed with sodium carbonate solution, and then acidified with nitric acid solution to obtain regenerated natural uranium extractant (i.e., purified organic phase).

[0009] In this invention, the natural uranium extractant is a conventional uranium extractant in the art, which includes tributyl phosphate and hydrogenated kerosene, wherein tributyl phosphate is used as the extractant and hydrogenated kerosene is used as the diluent; the mass content of tributyl phosphate in the natural uranium extractant is not strictly limited, for example, it can be about 30%.

[0010] During use, natural uranium extractants generate some known and unknown impurities. Known impurities include phosphoric acid, monobutyl phosphate (MBP), dibutyl phosphate (DBP), and trace amounts of uranium. Studies have shown that unknown impurities have a significant impact on the performance of regenerated natural uranium extractants. Existing methods for removing known impurities are not very effective at removing unknown impurities, resulting in poor performance recovery of the regenerated natural uranium extractants.

[0011] Through extensive research, the inventors have discovered that washing natural uranium extractant with sodium carbonate solution can remove some degradation products and trace amounts of uranium. The mechanism may include: sodium carbonate reacts with monobutyl phosphate and dibutyl phosphate to form water-soluble substances, while uranium undergoes a complexation reaction to form tricarbonate complexes, which are then dissolved in water and removed. Simultaneously, the main function of acid washing is to acidify the solvent, reducing the extraction of nitric acid by TBP after the organic phase recycles into the extraction system, maintaining the acidity of the system, ensuring the acidity requirements of subsequent processes, and allowing for continued normal operation. It also removes some radioactive substances from the organic phase after alkaline washing and destroys emulsions. More importantly, washing with sodium hydroxide solution first can effectively remove unknown impurities that traditional methods cannot handle. Combined with the subsequent sodium carbonate solution washing step, this maximizes the removal of impurities such as metallic uranium, further improving the purification effect and ensuring the performance recovery of the regenerated natural uranium extractant.

[0012] The following are some of the reaction equations that may be involved in sodium hydroxide washing:

[0013] (C4H9O)3PO+NaOH→(C4H9O)2POONa+C4H9OH (1)

[0014] (C4H9O)2PONa+NaOH→(C4H9O)POONa2+C4H9OH (2)

[0015] (C4H9O)POONa2+NaOH→Na3PO4+C4H9OH (3)

[0016] The following are some of the reaction equations that may be involved in the acid washing process with nitric acid solution:

[0017] NaOH + HNO3 → NaNO3 + H2O (4)

[0018] HNO3 + TBP → HNO3·TBP (5)

[0019] The following are some of the reaction equations that may be involved in the washing with sodium carbonate solution after acid rinsing:

[0020] (C4H9)H2PO4+Na2CO3→(C4H9)Na2PO4+H2O+CO2(6)

[0021] 2(C4H9)2HPO4+Na2CO3→(C4H9)Na2PO4+H2O+CO2(7)

[0022] UO2(NO3)2+3Na2CO3→Na4UO2(CO3)3+2NaNO3(8)

[0023] The reaction equations that may be involved in the final nitric acid solution pickling process are the same as those in (4) and (5).

[0024] In this invention, the sodium hydroxide solution has a mass content of 2-3%; the sodium carbonate solution has a mass content of 4-6%; and the nitric acid solution has a concentration of 1.5-2.5 mol / L. These concentrations are beneficial for reducing the loss of the organic phase during the purification process.

[0025] In this invention, washing and acidification are carried out in a pulsed extraction column. The two phases are in countercurrent contact within the extraction column, and the pulses increase the contact area between the two phases, thereby accelerating mass transfer efficiency.

[0026] Specifically, the washing process includes: feeding a natural uranium extractant into a pulse extraction column, simultaneously feeding a sodium hydroxide solution or a sodium carbonate solution into the pulse extraction column, mixing, and then allowing the mixture to stand for separation.

[0027] Acidification involves feeding the washed natural uranium extractant into a pulse extraction column, simultaneously feeding a nitric acid solution into the pulse extraction column, mixing, and then allowing it to stand for separation.

[0028] The flow rate of the natural uranium extractant entering the pulse extraction column is 7.5-8.5 m³. 3 The flow rate of sodium hydroxide solution, sodium carbonate solution, or nitric acid solution entering the pulse extraction column is 0.75-0.85 m³ / h. 3 / h.

[0029] Furthermore, the mixing is carried out under the conditions of a pulse frequency of 55-65 r / min and a gas source pressure of 0.11-0.13 MPa; in addition, the mixing time can be controlled to be 50-70 min and the settling and separation time to be 1-2 h.

[0030] This invention combines the practical production of natural uranium extraction and purification processes. Using sodium hydroxide, sodium carbonate, and nitric acid as organic phase purifying agents, a regeneration method for natural uranium extractant is designed. This reduces the uranium content in the regenerated natural uranium extractant to below 100 mg / L, and the uranium content in the regenerated natural uranium extractant is 0.5%-1% of the original content. Furthermore, known and unknown impurities in the natural uranium extractant do not affect its performance after the above regeneration treatment, allowing the regenerated natural uranium extractant to maintain good performance stably for a long period. This saves production costs, enables the reuse of the organic phase, reduces the pressure of tank storage, lowers the safety risks and management costs of the organic phase storage process, and ensures the stable operation of the oil removal process of the purification process's back-extraction solution, reducing operational risks and promoting cost reduction and efficiency improvement in the natural uranium purification production line. Attached Figure Description

[0031] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 is a process flow diagram of a method for regenerating natural uranium extractant according to one embodiment;

[0033] Figure 2 is a schematic diagram of the operation process of a pulse extraction column according to one embodiment. Detailed Implementation

[0034] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0035] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0036] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] Referring to Figures 1 and 2, this embodiment regenerates the used natural uranium extractant, which includes tributyl phosphate and hydrogenated kerosene, with the tributyl phosphate content being 30% by mass. The regeneration steps are as follows:

[0039] 1. Washing with sodium hydroxide:

[0040] Prepare a 2.5% sodium hydroxide solution (i.e., the purifying agent) in the purifying agent storage tank, and prepare the organic phase to be purified (i.e., the natural uranium extractant to be regenerated) in the organic phase storage tank.

[0041] The pulse frequency of the pulse extraction column was adjusted to 60 r / min, and the gas source pressure was 0.12 MPa. The organic phase (natural uranium extractant to be regenerated) was introduced at an 8m... 3 A flow rate of / h is introduced into the pulse extraction column, while the purging agent (2.5% sodium hydroxide solution) is introduced at a rate of 0.8m. 3 The flow rate is countercurrently fed into the pulse extraction column at a rate of / h. After the pulse extraction column is filled with liquid, the two-phase feed is stopped. The two phases are mixed in the pulse extraction column for 1 hour. After mixing, the column is allowed to stand for 1.5 hours. After the two phases are separated in the pulse extraction column, the aqueous phase containing impurities is discharged from the bottom to the waste liquid storage tank. Only the organic phase remains in the pulse extraction column. The organic phase is then discharged to the purified organic phase storage tank.

[0042] 2. Acidification:

[0043] Prepare a 2 mol / L nitric acid solution (i.e., the purifying agent) in the purifying agent storage tank, and prepare the purified organic phase (i.e., the natural uranium extractant washed with sodium hydroxide in step 1) in the organic phase storage tank. The pulse frequency of the pulse extraction column is 60 r / min, the gas source pressure is 0.12 MPa, and the organic phase is extracted at an 8 m... 3 A flow rate of / h is introduced into the pulse extraction column, while the purifying agent (2 mol / L nitric acid solution) is introduced at a flow rate of 0.8m. 3 A flow rate of / h is introduced into the pulse extraction column. After the pulse extraction column is filled with liquid, the two-phase feed is stopped. The two phases are mixed in the pulse extraction column for 1 hour. After the mixing is completed, the column is allowed to stand for 1.5 hours. After the two phases are separated in the pulse extraction column, the aqueous phase containing impurities is discharged from the bottom to the waste liquid storage tank. Only the organic phase remains in the pulse extraction column. The organic phase is then discharged to the purified organic phase storage tank.

[0044] 3. Two sodium carbonate washes:

[0045] A 5% sodium carbonate solution (i.e., the purifying agent) is prepared in the purifying agent storage tank, and the purified organic phase (i.e., the natural uranium extractant after acidification in step 2) is prepared in the organic phase storage tank. The pulse frequency of the pulse extraction column is 60 r / min, the gas source pressure is 0.12 MPa, and the organic phase is prepared at an 8m... 3 A flow rate of / h is introduced into the pulse extraction column, while the purifying agent (5% sodium carbonate solution) is introduced at a flow rate of 0.8m. 3 A flow rate of / h is introduced into the pulse extraction column. After the pulse extraction column is filled with liquid, the two-phase feed is stopped. The two phases are mixed in the pulse extraction column for 1 hour. After the mixing is completed, the column is allowed to stand for 1.5 hours. After the two phases are separated in the pulse extraction column, the aqueous phase containing impurities is discharged from the bottom to the waste liquid storage tank. Only the organic phase remains in the pulse extraction column. The organic phase is then discharged to the purified organic phase storage tank.

[0046] After one complete sodium carbonate wash as described above, the organic phase is washed again with sodium carbonate using the same method described above, thus completing two sodium carbonate washes.

[0047] 4. Acidification:

[0048] Prepare a 2 mol / L nitric acid solution (i.e., the purifying agent) in the purifying agent storage tank, and prepare the purified organic phase (i.e., the natural uranium extractant after two sodium carbonate washes in step 3) in the organic phase storage tank. The pulse frequency of the pulse extraction column is 60 r / min, the gas source pressure is 0.12 MPa, and the organic phase is prepared at an 8 m... 3 A flow rate of / h is introduced into the pulse extraction column, while the purifying agent (2 mol / L nitric acid solution) is introduced at a flow rate of 0.8m. 3 A flow rate of / h is introduced into the pulse extraction column. After the pulse extraction column is filled with liquid, the two-phase feed is stopped. The two phases are mixed in the pulse extraction column for 1 hour. After mixing, the column is allowed to stand for 1.5 hours. After the two phases are separated in the pulse extraction column, the aqueous phase containing impurities is discharged from the bottom to the waste liquid storage tank. Only the organic phase remains in the pulse extraction column. The organic phase is then discharged to the purified organic phase storage tank to obtain the regenerated natural uranium extractant.

[0049] The uranium content in the regenerated natural uranium extractant was tested, and the results showed that the uranium content in the regenerated natural uranium extractant was 0.5% of the uranium content in the natural uranium extractant before regeneration.

[0050] Example 2

[0051] The natural uranium extractant to be regenerated in this embodiment is the same as in Example 1; the regeneration steps are as follows:

[0052] 1. Washing with sodium hydroxide:

[0053] Prepare a 2% sodium hydroxide solution (i.e., the purifying agent) in the purifying agent storage tank, and prepare the organic phase to be purified (i.e., the natural uranium extractant to be regenerated) in the organic phase storage tank.

[0054] The pulse frequency of the pulse extraction column was adjusted to 65 r / min, and the gas source pressure was 0.11 MPa. The organic phase (natural uranium extractant to be regenerated) was introduced at a flow rate of 7.5 m. 3 A flow rate of / h is introduced into the pulse extraction column, while the purging agent (2% sodium hydroxide solution) is introduced at a rate of 0.75m. 3 The flow rate is countercurrently fed into the pulse extraction column at a rate of / h. After the pulse extraction column is filled with liquid, the two phases are stopped. The two phases are mixed in the pulse extraction column for 50 minutes. After mixing, the column is allowed to stand for 1 hour. After the two phases are separated in the pulse extraction column, the aqueous phase containing impurities is discharged from the bottom to the waste liquid storage tank. Only the organic phase remains in the pulse extraction column. The organic phase is then discharged to the purified organic phase storage tank.

[0055] 2. Acidification:

[0056] A 1.5 mol / L nitric acid solution (i.e., the purifying agent) was prepared in the purifying agent storage tank, and the purified organic phase (i.e., the natural uranium extractant washed with sodium hydroxide in step 1) was prepared in the organic phase storage tank. The pulse frequency of the pulse extraction column was 65 r / min, the gas source pressure was 0.11 MPa, and the organic phase was prepared at a flow rate of 7.5 m. 3 A flow rate of / h is introduced into the pulse extraction column, while the purifying agent (1.5 mol / L nitric acid solution) is introduced at a flow rate of 0.75m. 3 A flow rate of / h is introduced into the pulse extraction column. After the pulse extraction column is filled with liquid, the two-phase feed is stopped. The two phases are mixed in the pulse extraction column for 50 minutes. After mixing, the column is allowed to stand for 1 hour. After the two phases are separated in the pulse extraction column, the aqueous phase containing impurities is discharged from the bottom to the waste liquid storage tank. Only the organic phase remains in the pulse extraction column. The organic phase is then discharged to the purified organic phase storage tank.

[0057] 3. Two sodium carbonate washes:

[0058] A 6% sodium carbonate solution (i.e., the purifying agent) was prepared in the purifying agent storage tank, and the purified organic phase (i.e., the natural uranium extractant after acidification in step 2) was prepared in the organic phase storage tank. The pulse frequency of the pulse extraction column was 65 r / min, the gas source pressure was 0.11 MPa, and the organic phase was prepared at a flow rate of 7.5 m. 3 A flow rate of / h is introduced into the pulse extraction column, while the purifying agent (6% sodium carbonate solution) is introduced at a flow rate of 0.75m. 3A flow rate of / h is introduced into the pulse extraction column. After the pulse extraction column is filled with liquid, the two-phase feed is stopped. The two phases are mixed in the pulse extraction column for 50 minutes. After mixing, the column is allowed to stand for 1 hour. After the two phases are separated in the pulse extraction column, the aqueous phase containing impurities is discharged from the bottom to the waste liquid storage tank. Only the organic phase remains in the pulse extraction column. The organic phase is then discharged to the purified organic phase storage tank.

[0059] After one complete sodium carbonate wash as described above, the organic phase is washed again with sodium carbonate using the same method described above, thus completing two sodium carbonate washes.

[0060] 4. Acidification:

[0061] A 1.5 mol / L nitric acid solution (i.e., the purifying agent) was prepared in the purifying agent storage tank, and the purified organic phase (i.e., the natural uranium extractant after two sodium carbonate washes in step 3) was prepared in the organic phase storage tank. The pulse frequency of the pulse extraction column was 65 r / min, the gas source pressure was 0.11 MPa, and the organic phase was prepared at a flow rate of 7.5 m. 3 A flow rate of / h is introduced into the pulse extraction column, while the purifying agent (1.5 mol / L nitric acid solution) is introduced at a flow rate of 0.75m. 3 A flow rate of / h is introduced into the pulse extraction column. After the pulse extraction column is filled with liquid, the two-phase feed is stopped. The two phases are mixed in the pulse extraction column for 50 minutes. After mixing, the column is allowed to stand for 1 hour. After the two phases are separated in the pulse extraction column, the aqueous phase containing impurities is discharged from the bottom to the waste liquid storage tank. Only the organic phase remains in the pulse extraction column. The organic phase is then discharged to the purified organic phase storage tank to obtain the regenerated natural uranium extractant.

[0062] The uranium content in the regenerated natural uranium extractant was tested, and the results showed that the uranium content in the regenerated natural uranium extractant was 0.8% of the uranium content in the natural uranium extractant before regeneration.

[0063] Example 3

[0064] The natural uranium extractant to be regenerated in this embodiment is the same as in Example 1; the regeneration steps are as follows:

[0065] 1. Washing with sodium hydroxide:

[0066] Prepare a 3% sodium hydroxide solution (i.e., the purifying agent) in the purifying agent storage tank, and prepare the organic phase to be purified (i.e., the natural uranium extractant to be regenerated) in the organic phase storage tank.

[0067] The pulse frequency of the pulse extraction column was adjusted to 55 r / min, and the gas source pressure was 0.13 MPa. The organic phase (natural uranium extractant to be regenerated) was introduced at an 8.5 m... 3 A flow rate of / h is introduced into the pulse extraction column, while the purging agent (3% sodium hydroxide solution) is introduced at a rate of 0.85m. 3The flow rate is countercurrently fed into the pulse extraction column at a rate of / h. After the pulse extraction column is filled with liquid, the two-phase feed is stopped. The two phases are mixed in the pulse extraction column for 70 minutes. After mixing, the column is allowed to stand for 2 hours. After the two phases are separated in the pulse extraction column, the aqueous phase containing impurities is discharged from the bottom to the waste liquid storage tank. Only the organic phase remains in the pulse extraction column. The organic phase is then discharged to the purified organic phase storage tank.

[0068] 2. Acidification:

[0069] A 2.5 mol / L nitric acid solution (i.e., the purifying agent) was prepared in the purifying agent storage tank, and the purified organic phase (i.e., the natural uranium extractant washed with sodium hydroxide in step 1) was prepared in the organic phase storage tank. The pulse frequency of the pulse extraction column was 55 r / min, the gas source pressure was 0.13 MPa, and the organic phase was prepared at a flow rate of 8.5 m. 3 A flow rate of / h is introduced into the pulse extraction column, while the purifying agent (2.5 mol / L nitric acid solution) is introduced at a flow rate of 0.85m. 3 A flow rate of / h is introduced into the pulse extraction column. After the pulse extraction column is filled with liquid, the two-phase feed is stopped. The two phases are mixed in the pulse extraction column for 70 minutes. After mixing, the column is allowed to stand for 2 hours. After the two phases are separated in the pulse extraction column, the aqueous phase containing impurities is discharged from the bottom to the waste liquid storage tank. Only the organic phase remains in the pulse extraction column. The organic phase is then discharged to the purified organic phase storage tank.

[0070] 3. Two sodium carbonate washes:

[0071] A 4% sodium carbonate solution (i.e., the purifying agent) was prepared in the purifying agent storage tank, and the purified organic phase (i.e., the natural uranium extractant after acidification in step 2) was prepared in the organic phase storage tank. The pulse frequency of the pulse extraction column was 55 r / min, the gas source pressure was 0.13 MPa, and the organic phase was prepared at a flow rate of 8.5 m. 3 A flow rate of / h is introduced into the pulse extraction column, while the purging agent (4% sodium carbonate solution) is introduced at a flow rate of 0.85m. 3 A flow rate of / h is introduced into the pulse extraction column. After the pulse extraction column is filled with liquid, the two-phase feed is stopped. The two phases are mixed in the pulse extraction column for 70 minutes. After mixing, the column is allowed to stand for 2 hours. After the two phases are separated in the pulse extraction column, the aqueous phase containing impurities is discharged from the bottom to the waste liquid storage tank. Only the organic phase remains in the pulse extraction column. The organic phase is then discharged to the purified organic phase storage tank.

[0072] After one complete sodium carbonate wash as described above, the organic phase is washed again with sodium carbonate using the same method described above, thus completing two sodium carbonate washes.

[0073] 4. Acidification:

[0074] A 2.5 mol / L nitric acid solution (i.e., the purifying agent) was prepared in the purifying agent storage tank, and the purified organic phase (i.e., the natural uranium extractant after two sodium carbonate washes in step 3) was prepared in the organic phase storage tank. The pulse frequency of the pulse extraction column was 55 r / min, the gas source pressure was 0.13 MPa, and the organic phase was prepared at a flow rate of 8.5 m. 3 A flow rate of / h is introduced into the pulse extraction column, while the purifying agent (2.5 mol / L nitric acid solution) is introduced at a flow rate of 0.85m. 3 A flow rate of / h is introduced into the pulse extraction column. After the pulse extraction column is filled with liquid, the two-phase feed is stopped. The two phases are mixed in the pulse extraction column for 70 minutes. After mixing, the column is allowed to stand for 2 hours. After the two phases are separated in the pulse extraction column, the aqueous phase containing impurities is discharged from the bottom to the waste liquid storage tank. Only the organic phase remains in the pulse extraction column. The organic phase is then discharged to the purified organic phase storage tank to obtain the regenerated natural uranium extractant.

[0075] The uranium content in the regenerated natural uranium extractant was tested, and the results showed that the uranium content in the regenerated natural uranium extractant was 1.0% of the uranium content in the natural uranium extractant before regeneration.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for regenerating a natural uranium extractant, characterized in that, The natural uranium extractant includes tributyl phosphate and hydrogenated kerosene. The regeneration method includes the following steps in sequence: S1: Washing the natural uranium extractant to be regenerated with sodium hydroxide solution, followed by acidification with nitric acid solution; S2: Washing the natural uranium extractant after washing and acidification in step S1 with sodium carbonate solution, followed by acidification with nitric acid solution to obtain regenerated natural uranium extractant; wherein the mass content of sodium hydroxide solution is 2-3%; the mass content of sodium carbonate solution is 4-6%; and the concentration of nitric acid solution is 1.5-2.5 mol / L; washing and acidification are carried out in a pulse extraction column; washing includes: feeding the natural uranium extractant into the pulse extraction column, simultaneously feeding the sodium hydroxide solution or sodium carbonate solution into the pulse extraction column, mixing, and then allowing it to stand for separation; acidification includes: feeding the washed natural uranium extractant into the pulse extraction column, simultaneously feeding the nitric acid solution into the pulse extraction column, mixing, and then allowing it to stand for separation; wherein the flow rate of the natural uranium extractant entering the pulse extraction column is 7.5-8.5 m. 3 The flow rate of sodium hydroxide solution, sodium carbonate solution, or nitric acid solution entering the pulse extraction column is 0.75-0.85 m³ / h. 3 The mixing is carried out at a pulse frequency of 55-65 r / min and a gas source pressure of 0.11-0.13 MPa, with the mixing time controlled at 50-70 min and the settling and separation time at 1-2 h.

2. The regeneration method according to claim 1, characterized in that, The uranium content in the recycled natural uranium extractant is below 100 mg / L.

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