A high vacuum magnetic field assisted electromigration system and method for purification of uranium metal

Abstract

A kind of high vacuum magnetic field assisted electromigration system and method for uranium metal purification, including glove box, furnace body, vacuum system, argon bottle, furnace body is installed at the top of glove box, and there is anode, cathode in furnace body, tantalum joint is connected and fixed on anode, cathode;While experimental uranium metal is installed between anode, cathode by tantalum joint;And there is magnetic induction coil on the periphery of furnace body, to form magnetic field;Power cabinet is connected anode, cathode, and power supply is carried out;Furnace body is connected vacuum system by pipeline;Argon bottle is connected furnace body.Electromigration method, including S1: experimental uranium metal surface treatment;S2: sample furnace;Experimental uranium metal is clamped in furnace body, and experimental uranium metal is connected by tantalum joint at upper and lower ends;S3: equipment atmosphere replacement;S4: furnace high vacuum extraction;S5: sample heating.

Description

Technical Field

[0001] This invention relates to the field of radioactive metal purification technology, specifically to a high-vacuum magnetic field-assisted electromigration system and method for uranium metal purification. Background Technology

[0002] Solid-state electrotransport (SSE) is a purification technique that uses a DC electric field to drive the directional migration of impurity atoms in a metal. By heating the metal to near its melting point through Joule heating and maintaining it in a solid state, impurities are enriched at the electrode ends, and then the two ends are removed to obtain high-purity metal. This technique has been applied in the purification of high-melting-point metals such as tungsten and molybdenum, as well as some rare earth metals.

[0003] However, this technology faces some technical challenges in the field of radioactive uranium metal purification: uranium has an extremely strong oxygen affinity at high temperatures, and under conventional process vacuum conditions (10⁻⁶), it is difficult to achieve the desired oxygen absorption. -4 Even at 1000 Pa, an oxide layer still forms on the surface of the uranium sample. This oxide layer not only hinders impurity migration but also causes an abnormal increase in sample resistivity, leading to a risk of localized overheating. The melting point of uranium metal is close to the optimal operating temperature range for solid-state electromigration. Traditional processes suffer from a high sample melting rate due to uneven thermal conduction of residual gas in the vacuum system and abrupt changes in localized resistance of the oxide layer. Furthermore, traditional processes lack a closed-loop design specifically for radioactive metals, potentially generating secondary contamination waste.

[0004] The aforementioned problems make it difficult for existing technologies to meet the purity requirements of uranium metal, and are accompanied by sample melting and contamination issues. Therefore, there is an urgent need to develop an innovative process that integrates ultra-high vacuum control, magnetic field-assisted migration, and radioactive containment treatment to overcome the technical barriers to uranium metal electromigration purification.

[0005] This patent is mainly used to address the needs of a uranium metal electromigration purification process, solving key problems such as maintaining ultra-high vacuum, magnetic field-assisted migration, and radioactive encapsulation, overcoming the aforementioned limitations, and achieving the purification of uranium metal. Summary of the Invention

[0006] The purpose of this invention is to provide a high-vacuum magnetic field-assisted electromigration system and method for uranium metal purification, which solves key problems such as maintaining ultra-high vacuum, magnetic field-assisted migration and radioactive encapsulation under ultra-high vacuum conditions, achieving zero waste liquid / solid waste discharge and a total uranium metal impurity removal rate of ≥40%.

[0007] The technical solution of the present invention is as follows: A high-vacuum magnetic field-assisted electromigration system for uranium metal purification includes a glove box, a furnace body, a vacuum system, and an argon cylinder. The furnace body is installed on the top of the glove box, and there are positive and negative electrodes inside the furnace body. Tantalum connectors are fixed to the positive and negative electrodes. The experimental uranium metal is installed between the positive and negative electrodes through the tantalum connectors. A magnetic induction coil is located around the furnace body to form a magnetic field. A power supply cabinet is connected to the positive and negative electrodes to provide power. The furnace body is connected to the vacuum system through pipelines. The argon cylinder is connected to the furnace body.

[0008] The vacuum system includes an ion pump, a molecular pump, and a mechanical pump; the furnace body is connected to the ion pump through a pipeline, and there is a gate valve B on the connecting pipeline; the furnace body is also connected to the mechanical pump and the molecular pump through pipelines, and there are solenoid valves A and gate valves A on the connecting pipelines respectively; the mechanical pump is connected to the molecular pump through a pipeline, and there is a solenoid valve B on the connecting pipeline.

[0009] The anode and cathode are made of oxygen-free copper.

[0010] A high-vacuum magnetic field-assisted electromigration method for uranium metal purification includes the following steps:

[0011] S1: Experimental uranium metal surface treatment;

[0012] S2: Sample loading; The experimental uranium metal is clamped in the furnace body, and the upper and lower ends of the experimental uranium metal are connected by tantalum joints;

[0013] S3: Atmosphere replacement within the equipment; turn on the mechanical pump, open solenoid valve A, wait for the vacuum inside the furnace to reach below 10 Pa, then open solenoid valve B and start the molecular pump to evacuate the furnace to 1×10 Pa. -4 After Pa, stop evacuating and replace the gas inside the furnace with high-purity argon from the argon cylinder.

[0014] S4: High vacuum evacuation inside the furnace; first, turn on the mechanical pump and solenoid valve A. Once the vacuum inside the furnace reaches below 10 Pa, turn on solenoid valve B, start the molecular pump, close solenoid valve A, and open gate valve A until the vacuum inside the furnace reaches 10 Pa. -4 Pa; Open gate valve B, turn on the ion pump, and continue to pump high vacuum;

[0015] S5: The sample is heated and the magnetic field is turned on; the current of the power cabinet is increased to heat the experimental uranium metal, and then the temperature is maintained; the magnetic induction coil around the furnace body is energized to form a magnetic field.

[0016] S6: Keep the experimental uranium metal at a constant temperature;

[0017] S7: Unload the furnace; after the heat preservation is completed, turn off the power cabinet and magnetic field; after cooling down, take out the experimental uranium metal and vacuum seal it to prevent oxidation.

[0018] In S1, test samples are prepared by machining, and the sample specifications are as follows: The uranium metal surface was then sanded, cleaned with alcohol and acetone, and then cleaned with a Hall source to obtain experimental uranium metal 13.

[0019] In S3, the furnace body 8 is evacuated to 1×10 -4 After Pa, stop evacuating; in S4, evacuate to a high vacuum until the vacuum level inside the furnace reaches 10. -6 Pa.

[0020] In S5, the magnetic field strength reaches 0.3T.

[0021] In S5, the experimental uranium metal 13 was heated to a temperature 1.0 to 1.02 times its melting point.

[0022] In S6, the heat preservation time is 150 hours, and a vacuum is continuously applied during the heat preservation process.

[0023] In S7, experimental uranium metal 13 was cut in glove box 1 under an argon atmosphere.

[0024] The significant advantages of this invention are:

[0025] 1. This invention purifies uranium metal through electromigration, producing no byproducts such as waste liquid or solid waste, thus reducing the burden of radioactive waste disposal.

[0026] 2. The entire process of this invention is carried out under ultra-high vacuum, which reduces the oxidation of uranium metal during the experiment; the inert gas protection and sealed packaging of the sample improves the safety of radioactive operations.

[0027] 3. Through a series of electromigration purification processes, the uranium metal impurity removal rate reaches over 40%. Attached Figure Description

[0028] Figure 1 Process flow diagram of this invention;

[0029] Figure 2 Schematic diagram of the system of this invention;

[0030] In the diagram: 1. Glove box; 2. Argon cylinder; 3. Solenoid valve A; 4. Mechanical pump; 5. Solenoid valve B; 6. Molecular pump; 7. Gate valve A; 8. Furnace body; 9. Gate valve B; 10. Ion pump; 11. Anode; 12. Magnetic field; 13. Experimental uranium metal; 14. Tantalum connector; 15. Power cabinet; 16. Cathode. Detailed Implementation

[0031] Many specific details are set forth in the following description to provide a full understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this application; therefore, this application is not limited to the specific embodiments disclosed below.

[0032] The terminology used in one or more embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of one or more embodiments of this application. The singular forms “a,” “the,” and “the” used in one or more embodiments of this application and in the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” used in one or more embodiments of this application refers to and includes any or all possible combinations of one or more associated listed items.

[0033] It should be understood that although the terms first, second, etc., may be used to describe various information in one or more embodiments of this application, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, first may also be referred to as second without departing from the scope of one or more embodiments of this application, and similarly, second may also be referred to as first.

[0034] The specific technical content of the present invention will now be described with reference to the accompanying drawings;

[0035] like Figure 2 As shown, a high-vacuum magnetic field-assisted electromigration system for uranium metal purification includes a furnace body 8, which is connected to an ion pump 10 via a pipeline, and a gate valve B9 is provided on the connecting pipeline; the furnace body 8 is also connected to a mechanical pump 4 and a molecular pump 6 via pipelines, and a solenoid valve A3 and a gate valve A7 are provided on the connecting pipelines respectively; the mechanical pump 4 is connected to the molecular pump 6 via a pipeline, and a solenoid valve B5 is provided on the connecting pipeline.

[0036] The furnace body 8 is installed on top of the glove box 1, and the furnace body 8 contains an anode 11 and a cathode 16. The tantalum connector 14 is fixed to the anode 11 and cathode 16 by bolts. The experimental uranium metal 13 is installed between the anode 11 and cathode 16 through the tantalum connector 14. The furnace body 8 has a magnetic induction coil on its outer periphery, thereby forming a magnetic field 12. The power supply cabinet 15 is connected to the anode 11 and cathode 16 to provide power.

[0037] Preferably, the anode 11 and cathode 16 are made of oxygen-free copper;

[0038] It also includes argon cylinder 2, which is connected to furnace body 8 to provide high-purity argon gas to the interior of furnace body 8.

[0039] A high-vacuum magnetic field-assisted electromigration method for uranium metal purification includes the following steps:

[0040] (1) Surface treatment of the sample to be purified;

[0041] Test samples were prepared by machining, and the sample specifications were as follows: The uranium metal surface was then sanded to remove the oxide layer. The sample surface was cleaned with alcohol and acetone, followed by a Hall effect source cleaning to completely remove the oxide layer. This yielded the experimental uranium metal 13.

[0042] (2) Sample loading into the furnace;

[0043] The experimental uranium metal 13 is vertically clamped inside the furnace body 8, and the upper and lower ends of the experimental uranium metal 13 are connected by tantalum joints 14.

[0044] (3) Atmosphere replacement inside the equipment

[0045] After the furnace is loaded, the gas inside the furnace is replaced with high-purity argon gas, and the gas is repeatedly purged three times; the purity of the high-purity argon gas is 99.999%.

[0046] Specifically, after the furnace loading is completed, mechanical pump 4 is turned on, solenoid valve A3 is opened, and when the vacuum inside the furnace body 8 reaches below 10 Pa, solenoid valve B5 is opened, and molecular pump 6 is started to evacuate the furnace body 8 to 1×10 Pa. -4 After Pa, stop evacuation and replace the gas in furnace body 8 with high-purity argon gas from argon cylinder 2. Repeat the evacuation and purging process 3 times. The purity of the high-purity argon gas is 99.999%.

[0047] (4) High vacuum in the furnace

[0048] After the atmosphere replacement is completed, vacuuming begins until the vacuum level inside the furnace body reaches 10. -6 Pa;

[0049] Specifically, first turn on mechanical pump 4, then open solenoid valve A3. Once the vacuum inside the furnace reaches below 10 Pa, open solenoid valve B5, start molecular pump 6, close solenoid valve A3, and open gate valve A7 until the vacuum inside the furnace body 8 reaches 10 Pa. -4 Pa; Open gate valve B9, turn on ion pump 10, and continue pumping high vacuum until the vacuum level reaches 10. -6 Pa;

[0050] (5) Heat the sample and turn on the magnetic field;

[0051] The current in the power supply cabinet 15 is slowly increased until the experimental uranium metal 13 reaches a heating temperature of 1050℃-1150℃, at which point the temperature is maintained. Magnetic induction coils are energized around the outer perimeter of the furnace body 8, thus creating a magnetic field 12.

[0052] Preferably, the magnetic field strength of magnetic field 12 reaches 0.3T.

[0053] (6) Sample insulation

[0054] The experimental uranium metal 13 was kept at a constant temperature, and temperature changes were carefully observed and the power was adjusted in a timely manner to avoid the uranium metal 13 melting due to excessive power-temperature rise. A vacuum was continuously applied during the temperature holding process. The sample was kept at a constant temperature for 150 hours.

[0055] (7) Remove from oven

[0056] After the heat preservation process is completed, the power supply cabinet 15 and magnetic field 12 are turned off. After cooling down, the experimental uranium metal 13 is taken out and promptly vacuum-sealed to prevent oxidation, and placed in a glove box. The experimental uranium metal 13 is cut in an argon glove box, and the cutting waste is stored in a container.

[0057] In the above method, the temperature of the uranium metal rod is slightly higher than its melting point. Because uranium remains solid during electromigration at its melting point, the temperature is 0.9 to 1.02 times its melting point, preferably 1.0 to 1.02 times its melting point. After a period of time, uranium metal with high purity can be obtained.

[0058] Example 1: Purification of uranium metal under different vacuum conditions

[0059] Metallic uranium was made into a rod with a diameter of 5 mm and a length of 150 mm, and then subjected to a vacuum of 10... -6 The uranium metal was treated with solid-state electromigration at 1150℃ for 50 hours, after which the carbon and total impurity contents decreased from 780 ppm and 830 ppm to 540 ppm and 590 ppm, respectively, with removal rates of 30.8% and 28.9%.

[0060] Comparative Example 1

[0061] Metallic uranium was made into a rod with a diameter of 5 mm and a length of 150 mm, and then subjected to a vacuum of 10... -4 The uranium metal was kept at 1150℃ for 50 hours under the conditions of Pa. After solid-state electromigration treatment, the C and total impurity contents in the uranium metal decreased from 730 ppm and 800 ppm to 550 ppm and 650 ppm, respectively, with removal rates of 24.7% and 18.8%.

[0062] Example 2: Purification of uranium metal under different magnetic field conditions

[0063] Metallic uranium was made into a rod with a diameter of 5 mm and a length of 150 mm, and then subjected to a vacuum of 10... -6The uranium metal was kept at 1150℃ and 0.3T for 150 hours under the following conditions: Pa, temperature, and magnetic field. After solid-state electromigration treatment, the contents of C, Fe, and total impurities in the uranium metal decreased from 580ppm, 150ppm, and 780ppm to 300ppm, 80ppm, and 450ppm, respectively, with removal rates of 48.3%, 46.7%, and 42.3%.

[0064] Comparative Example 2

[0065] Metallic uranium was made into a rod with a diameter of 5 mm and a length of 150 mm, and then subjected to a vacuum of 10... -6 The solid-state electromigration treatment was carried out at 1150℃ for 150 hours. After the treatment, the contents of C, Fe and total impurities in uranium metal decreased from 650ppm, 170ppm and 850ppm to 410ppm, 110ppm and 670ppm, respectively, with removal rates of 32%, 35.3% and 22.8%.

[0066] The results of the two sets of comparative experiments above show that, compared with conventional solid-state electromigration methods, the purification of uranium metal under the high-vacuum magnetic field-assisted conditions of this invention achieves better purification results under the same conditions, and the contents of C, Fe, and total impurities can be reduced by at least 40%.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0068] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0069] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0070] The preferred embodiments disclosed above are merely illustrative of this application. The optional embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this application. These embodiments are selected and specifically described in this application to better explain the principles and practical applications of this application, thereby enabling those skilled in the art to better understand and utilize this application.

Claims

1. A high-vacuum magnetic field-assisted electromigration system for uranium metal purification, characterized in that: The system includes a glove box (1), a furnace body (8), a vacuum system, and an argon cylinder (2). The furnace body (8) is installed on top of the glove box (1), and the furnace body (8) contains an anode (11) and a cathode (16). A tantalum connector (14) is connected and fixed to the anode (11) and cathode (16). The experimental uranium metal (13) is installed between the anode (11) and cathode (16) through the tantalum connector (14). The furnace body (8) has a magnetic induction coil on its outer periphery, thereby forming a magnetic field (12). The power cabinet (15) is connected to the anode (11) and cathode (16) to provide power. The furnace body (8) is connected to the vacuum system through a pipeline. The argon cylinder (2) is connected to the furnace body (8).

2. The high-vacuum magnetic field-assisted electromigration system for uranium metal purification according to claim 1, characterized in that: The vacuum system includes an ion pump (10), a molecular pump (6), and a mechanical pump (4); the furnace body (8) is connected to the ion pump (10) through a pipeline, and there is a gate valve B (9) on the connecting pipeline; the furnace body (8) is also connected to the mechanical pump (4) and the molecular pump (6) through pipelines, and there are solenoid valves A (3) and gate valves A (7) on the connecting pipelines respectively; the mechanical pump (4) is connected to the molecular pump (6) through a pipeline, and there is a solenoid valve B (5) on the connecting pipeline.

3. The high-vacuum magnetic field-assisted electromigration system for uranium metal purification according to claim 1, characterized in that: The anode (11) and cathode (16) are made of oxygen-free copper.

4. A high-vacuum magnetic field-assisted electromigration method for uranium metal purification, using the system described in claim 2, characterized in that: Includes the following steps: S1: Surface treatment of experimental uranium metal (13); S2: Sample loading; The experimental uranium metal (13) is clamped in the furnace body (8), and the upper and lower ends of the experimental uranium metal (13) are connected by tantalum connectors (14); S3: Atmosphere replacement within the equipment; Turn on the mechanical pump (4), open the solenoid valve A (3), wait until the vacuum inside the furnace body (8) reaches below 10 Pa, open the solenoid valve B (5), start the molecular pump (6), and evacuate the furnace body (8) to 1×10 Pa. -4 After Pa, stop evacuating and replace the gas in the furnace body (8) with high-purity argon gas from the argon cylinder (2); S4: Evacuate the furnace to a high vacuum; first turn on the mechanical pump (4), then turn on the solenoid valve A (3). Once the vacuum inside the furnace (8) reaches below 10 Pa, turn on the solenoid valve B (5), start the molecular pump (6), close the solenoid valve A (3), and open the gate valve A (7) until the vacuum inside the furnace (8) reaches 10 Pa. -4 Pa; Open gate valve B (9), turn on ion pump (10), and continue to pump high vacuum; S5: The sample is heated and the magnetic field is turned on; the current of the power cabinet (15) is increased to heat the experimental uranium metal (13), and then the heat is maintained; the magnetic induction coil around the furnace body (8) is energized to form a magnetic field (12). S6: Insulate the experimental uranium metal (13) at a constant temperature; S7: Remove from the furnace; after the heat preservation is completed, turn off the power cabinet (15) and magnetic field (12); after cooling down, take out the experimental uranium metal (13) and vacuum seal it to avoid oxidation.

5. The high-vacuum magnetic field-assisted electromigration method for uranium metal purification according to claim 4, characterized in that: In S1, the test sample was prepared by machining. The sample size was φ5×150mm. Then, the uranium metal surface was polished with sandpaper, and the sample surface was cleaned with alcohol and acetone. Finally, the sample surface was cleaned with a Hall source to obtain the experimental uranium metal (13).

6. The high-vacuum magnetic field-assisted electromigration method for uranium metal purification according to claim 4, characterized in that: In S3, the furnace body (8) is evacuated to 1×10 -4 After Pa, stop evacuating; in S4, evacuate to a high vacuum until the vacuum level inside the furnace body (8) reaches 10. -6 Pa.

7. The high-vacuum magnetic field-assisted electromigration method for uranium metal purification according to claim 4, characterized in that: In S5, the magnetic field (12) strength reaches 0.3T.

8. The high-vacuum magnetic field-assisted electromigration method for uranium metal purification according to claim 4, characterized in that: In S5, the experimental uranium metal (13) was heated to a temperature 1.0 to 1.02 times its melting point.

9. The high-vacuum magnetic field-assisted electromigration method for uranium metal purification according to claim 4, characterized in that: In S6, the heat preservation time is 150 hours, and a vacuum is continuously applied during the heat preservation process.

10. The high-vacuum magnetic field-assisted electromigration method for uranium metal purification according to claim 4, characterized in that: In S7, the experimental uranium metal (13) was cut in a glove box (1) under an argon atmosphere.

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