Electrolytic refining waste salt purification device, purification system and purification method

Abstract

The invention provides an electrolytic refining waste salt purification device, system and method. The electrolytic refining waste salt purification device comprises a heater, an oxidation precipitation crucible, a filtering hanging basket, an extraction hanging basket and a sealing end cover, the oxidation precipitation crucible is arranged in the heater; the filtering hanging basket is used for containing electrolytic refining waste salt, the filtering hanging basket is arranged in the oxidation precipitation crucible, and first filtering holes are formed in the filtering hanging basket; the extraction hanging basket is used for containing a solid metal extraction agent, the extraction hanging basket is arranged in the oxidation precipitation crucible, and second filtering holes are formed in the extraction hanging basket; and the sealing end cover is arranged at the top opening of the oxidation precipitation crucible. According to the electrolytic refining waste salt purification device, purification system and purification method provided by the invention, the defects that separation means of actinides and rare earth elements in electrolytic refining waste salt in the prior art are mutually independent, steps are dispersed, the process is tedious, the separation selectivity is poor and the salt entrainment rate is high are overcome.

Description

Technical Field

[0001] This invention relates to the field of electrolytic refining waste salt purification technology, and in particular to an electrolytic refining waste salt purification device, purification system and purification method. Background Technology

[0002] In the molten salt electrolytic refining process of spent metal fuel in fast reactors, most of the actinides dissolved at the anode are recovered at the cathode. However, a small amount of actinides remain in the electrolyte, which continuously accumulates fragmented elements such as rare earth and alkaline earth elements over time. When the impurity concentration exceeds the limits of the electrolysis process, the entire furnace of molten salt is deemed waste salt and must be purified before reuse. Therefore, developing efficient and low-entrainment waste salt purification methods is a key step in ensuring a closed-loop cycle for dry reprocessing.

[0003] To address these issues, existing technologies generally employ multi-stage countercurrent liquid metal reduction extraction or oxidation precipitation for separation. The former requires at least four stages of extraction to separate actinides from rare earth elements, resulting in bulky equipment, a large density difference between the two phases, and a tendency for phase stratification, making it difficult to engineer. While the latter can precipitate rare earth elements in one step, it also causes actinide co-precipitation, leading to the loss of valuable elements. Furthermore, the precipitate contains a high amount of molten salt, requiring additional processes such as demolding, cutting, and vacuum distillation to recover the entrained salt. This process is lengthy, energy-intensive, and generates a large amount of radioactive waste, making it difficult to meet the requirements for efficient, compact, and low-consumption reprocessing of fast reactor fuels. Summary of the Invention

[0004] This invention provides an electrolytic refining waste salt purification device, purification system, and purification method to solve the defects of existing technologies in separating actinides and rare earth elements in electrolytic refining waste salt, which are independent of each other, have scattered steps, have lengthy processes, poor separation selectivity, and high salt entrainment rate.

[0005] The first aspect of the present invention provides an electrolytic refining waste salt purification device, comprising: a heater, an oxidation precipitation crucible, a filter basket, an extraction basket, and a sealed end cap.

[0006] The oxidation precipitation crucible is located inside the heater; the filter basket is used to hold electrolytic refining waste salt, and is located inside the oxidation precipitation crucible. The filter basket has a first filter hole to connect the internal space of the filter basket with the oxidation precipitation crucible; the extraction basket is used to hold solid metal extractant, and is located inside the oxidation precipitation crucible. The extraction basket has a second filter hole to connect the internal space of the extraction basket with the oxidation precipitation crucible; the sealing end cap is located at the top opening of the oxidation precipitation crucible.

[0007] According to the electrolytic refining waste salt purification device provided by the present invention, a first filter screen is provided in the filter basket, and a third filter hole is provided on the first filter screen, the diameter of the third filter hole being smaller than the diameter of the first filter hole; and / or, a second filter screen is provided in the extraction basket, and a fourth filter hole is provided on the second filter screen, the diameter of the fourth filter hole being smaller than the diameter of the second filter hole.

[0008] The electrolytic refining waste salt purification apparatus provided by the present invention includes a plurality of the extraction baskets.

[0009] The electrolytic refining waste salt purification apparatus provided by the present invention further includes: a stirring paddle, wherein the stirring end of the stirring paddle is located inside the oxidation precipitation crucible, and is used to stir the molten material inside the oxidation precipitation crucible.

[0010] The electrolytic refining waste salt purification device provided by the present invention further includes: a sampler, wherein the sampler is inserted through the sealed end cap so that the sampling end of the sampler is located inside the oxidation precipitation crucible, for sampling and processing the material in the oxidation precipitation crucible.

[0011] The electrolytic refining waste salt purification apparatus provided by the present invention further includes: a crucible basket, wherein the oxidation precipitation crucible is disposed in the crucible basket.

[0012] The electrolytic refining waste salt purification device provided by the present invention further includes: a leak-proof sleeve, wherein the leak-proof sleeve is disposed inside the heater, and the oxidation precipitation crucible is disposed inside the leak-proof sleeve.

[0013] According to the electrolytic refining waste salt purification apparatus provided by the present invention, the oxidation precipitation crucible is made of graphite material; and / or, the filter basket is made of stainless steel material; and / or, the extraction basket is made of stainless steel material.

[0014] A second aspect of the present invention provides an electrolytic refining waste salt purification system, comprising: an electrolytic refining waste salt purification device, a glove box, and a hoisting assembly.

[0015] The lifting assembly is used to lift at least one of the following: oxidation precipitation crucible, filter basket, extraction basket, sealing end cap, and crucible basket. The lifting assembly is located inside the glove box.

[0016] The third aspect of the present invention provides a method for purifying waste salt from electrolytic refining, implemented based on an electrolytic refining waste salt purification system, comprising the following steps.

[0017] Place the filter basket in the oxidation precipitation crucible, and add the first set weight of electrolytic refining waste salt into the filter basket.

[0018] Cover with the sealed end cap, start the heater, and heat the electrolytic refining waste salt at the first set temperature until it is completely melted.

[0019] Remove the sealed end cap, and use the lifting assembly to place the extraction basket containing the solid metal extractant into the oxidation precipitation crucible, so that the extraction basket is immersed in the molten salt, and then replace the sealed end cap.

[0020] Start the agitator and maintain the first set speed to keep the molten salt in continuous contact with the solid metal extractant until the concentration of actinides in the molten salt drops to the first set content.

[0021] Stop stirring, remove the sealed end cap, and use the lifting assembly to remove the extraction basket to complete the recovery of actinides.

[0022] Add an oxidizing precipitant to the oxidizing precipitant crucible until the amount of oxidizing precipitant added reaches the second set weight.

[0023] Replace the sealing end cap, start the agitator, and maintain the second set speed until the rare earth element concentration in the molten salt drops to the second set content.

[0024] Stop stirring and use the hoisting assembly to lift the filter basket to the set height, so that the bottom of the filter basket is higher than the molten salt surface, for static filtration.

[0025] After the molten salt has completely flowed into the oxidation precipitation crucible through the first filter hole and the first filter screen, heating is stopped, and the crucible is cooled to room temperature to obtain purified salt ingots.

[0026] The electrolytic refining waste salt purification device provided by this invention integrates a heater, an oxidation precipitation crucible, an extraction basket, a filter basket, and a sealed end cap into the same sealed space. It can first complete the reduction extraction of actinides in the molten salt state using the extraction basket and remove the whole thing. Then, in the same oxidation precipitation crucible, the filter basket is switched to perform rare earth oxidation precipitation. After precipitation, the filter basket can be directly lifted to achieve efficient solid-liquid separation of precipitate and molten salt, and significantly reduce the amount of molten salt entrained. It solves the problems of existing technologies such as large size of multi-stage countercurrent extraction equipment, high risk of phase separation, large loss of actinides co-precipitation in oxidation precipitation method, and the need for subsequent demolding, cutting, and vacuum distillation to recover entrained salt, resulting in a long process, high energy consumption, and large amount of radioactive waste.

[0027] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is one of the schematic diagrams of the electrolytic refining waste salt purification device provided in the embodiments of the present invention.

[0030] Figure 2 This is the second schematic diagram of the electrolytic refining waste salt purification device provided in the embodiment of the present invention.

[0031] Figure 3 This is a schematic diagram of the filter basket in the electrolytic refining waste salt purification device provided in an embodiment of the present invention.

[0032] Figure 4 This is a schematic diagram of the extraction basket in the electrolytic refining waste salt purification device provided in an embodiment of the present invention.

[0033] Figure 5 This is one of the schematic diagrams of the electrolytic refining waste salt purification system provided in the embodiments of the present invention.

[0034] Figure 6 This is the second schematic diagram of the electrolytic refining waste salt purification system provided in the embodiments of the present invention.

[0035] Figure 7 This is a schematic flowchart of the electrolytic refining waste salt purification method provided in the embodiments of the present invention.

[0036] Figure 8 This is a schematic diagram of the mechanism of the electrolytic refining waste salt purification method provided in the embodiments of the present invention.

[0037] Figure label: 100. Electrolytic refining waste salt purification device; 101. Heater; 102. Oxidation precipitation crucible; 103. Filter basket; 104. Extraction basket; 105. Sealing end cap; 106. Stirring paddle; 107. Sampler; 108. Crucible basket; 109. Leak-proof sleeve; 200. Glove box; 300. Lifting assembly. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0039] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0040] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0041] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0042] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0043] The following is combined Figures 1 to 8 This invention describes the electrolytic refining waste salt purification device, purification system, and purification method provided by the present invention.

[0044] See Figures 1 to 4 As shown, the electrolytic refining waste salt purification device 100 provided in this embodiment of the invention includes: a heater 101, an oxidation precipitation crucible 102, a filter basket 103, an extraction basket 104, and a sealing end cap 105.

[0045] An oxidation precipitation crucible 102 is disposed inside a heater 101; a filter basket 103 is used to hold electrolytic refining waste salt, and is disposed inside the oxidation precipitation crucible 102. The filter basket 103 is provided with a first filter hole to connect the internal space of the filter basket 103 with the oxidation precipitation crucible 102; an extraction basket 104 is used to hold a solid metal extractant, and is disposed inside the oxidation precipitation crucible 102. The extraction basket 104 is provided with a second filter hole to connect the internal space of the extraction basket 104 with the oxidation precipitation crucible 102; a sealing end cap 105 is disposed at the top opening of the oxidation precipitation crucible 102.

[0046] It should be noted that electrolytic refining waste salt refers to decommissioned molten salt from fast reactor spent metal fuel, where most of the actinides have been recovered at the cathode, leaving only a small amount of actinides ions and enrichment in rare earth and alkaline earth fragments. This waste salt requires purification to remove impurities before it can be reused in the electrolysis process. The electrolytic refining waste salt purification device 100 is used to sequentially perform actinides reduction extraction, rare earth oxidation precipitation, and solid-liquid separation on the aforementioned decommissioned molten salt in the same sealed crucible. This allows the purified molten salt to be directly reused in the furnace, while simultaneously recovering valuable actinides metals, achieving waste salt resource utilization and a closed-loop dry process.

[0047] The electrolytic refining waste salt purification device 100 provided by the present invention integrates a heater 101, an oxidation precipitation crucible 102, an extraction basket 104, a filter basket 103, and a sealing end cap 105 into the same sealed space. It can first complete the reduction extraction of actinides in the molten salt state using the extraction basket 104 and remove the whole thing. Then, in the same oxidation precipitation crucible 102, the filter basket 103 is switched to carry out rare earth oxidation precipitation. After precipitation, the filter basket 103 is directly lifted to achieve efficient solid-liquid separation of precipitate and molten salt, and significantly reduce the amount of molten salt entrained. It solves the problems of large size of multi-stage countercurrent extraction equipment, high risk of phase separation, large loss of actinides co-precipitation in oxidation precipitation method, and the need for subsequent demolding, cutting, and vacuum distillation to recover entrained salt, which leads to a long process, high energy consumption, and large amount of radioactive waste in the prior art.

[0048] Specifically, heater 101 is used to program the temperature of oxidation precipitation crucible 102, so that the electrolytic refining waste salt melts in an inert atmosphere and is kept at a constant temperature, providing a molten salt environment for subsequent reactions.

[0049] As an example, in this embodiment, the heater 101 is a resistance wire heating furnace, which can continuously heat up within a specific temperature range (such as 600°C to 700°C) according to a set program and maintain a constant temperature, providing a stable and controllable molten salt environment for the oxidation precipitation crucible 102.

[0050] The oxidation precipitation crucible 102 is used to hold the filter basket 103 or the extraction basket 104 inside the heater 101 and to support the molten waste salt, providing an integrated reaction vessel for extraction, precipitation, and cooling demolding. The oxidation precipitation crucible 102 is preferably made of pyrolytic graphite, which utilizes its high temperature resistance and non-adhesive properties, allowing the salt ingot to be removed as a whole after cooling, avoiding residue.

[0051] The filter basket 103 is used to hold electrolytic refining waste salt in the initial stage, and after the precipitation reaction, the molten salt is lifted to flow back to the oxidation precipitation crucible 102 through the first filter hole, while rare earth oxides are retained in the basket, thus achieving solid-liquid separation. The filter basket 103 is preferably made of stainless steel, which can maintain structural strength and corrosion resistance in the high-temperature molten salt environment, avoid contaminating the molten salt, and extend its service life.

[0052] On the filter basket 103, the pore size of the first filter hole can be adjusted according to the molten salt viscosity and the target precipitate particle size, so as to balance rapid salt discharge and effective precipitate retention.

[0053] The extraction basket 104 is used to hold the solid metal extractant during the molten salt stage, allowing the molten salt to freely enter and exit the basket through the second filter hole, completing the reduction extraction of actinides. It can be removed as a whole after the reaction, achieving the initial separation of actinides from rare earth elements. Similarly, the extraction basket 104 is preferably made of stainless steel, which can withstand the chemical corrosion of high-temperature molten salt and metal extractant, maintaining structural integrity and preventing contamination.

[0054] On the extraction basket 104, the pore size of the second filter hole can be set according to the particle size of the metal extractant and the size of the reduction product to allow the molten salt to pass through smoothly and prevent the extractant or the generated actinide metal particles from leaking out.

[0055] In some embodiments, a detachable stainless steel interface may be provided at the top port of the extraction basket 104 for opening or closing the extraction basket 104.

[0056] It should be noted that the metal extractant is used to undergo a displacement reduction reaction with actinide ions in the molten salt, causing the actinide elements to deposit in a metallic state within the extraction basket 104, without introducing new impurity ions into the system, thereby achieving selective recovery of valuable actinides. For example, lanthanum, cerium, or lanthanum-cerium alloy particles can be used as the metal extractant, as their reduction potential is higher than that of actinide ions. They can reduce uranium, plutonium, etc., to metals (actinide metals) in the molten salt and retain them within the extraction basket 104. Furthermore, after entering the molten salt in ionic form, they can be subsequently removed by oxidation precipitation without adding additional impurities.

[0057] The sealing end cap 105 is used to seal the top opening of the oxidation precipitation crucible 102, maintain an inert atmosphere of no water and no oxygen inside the crucible, prevent the molten salt from absorbing moisture and oxidizing, and block the leakage of radioactive aerosols.

[0058] During operation, components such as the oxidation precipitation crucible 102, the filter basket 103, the extraction basket 104, and the sealing end cap 105 can all be picked up, placed, and transferred manually or with the help of simple lifting tools, achieving the complete extraction-precipitation-filtration process without relying on automated mechanisms.

[0059] According to some embodiments of the present invention, a first filter screen (not shown in the figure) is provided in the filter basket 103, and a third filter hole is provided on the first filter screen, the diameter of the third filter hole being smaller than the diameter of the first filter hole; a second filter screen (not shown in the figure) is provided in the extraction basket 104, and a fourth filter hole is provided on the second filter screen, the diameter of the fourth filter hole being smaller than the diameter of the second filter hole.

[0060] By adding a first filter screen with a smaller pore size and a second filter screen with a smaller pore size to the filter basket 103 and the extraction basket 104 respectively, the fine pore layer can be used to intercept the precipitated particles or reduced metal powder for a second time, preventing them from passing through the basket wall with the molten salt flow. This ensures the smooth passage of molten salt while improving the solid-liquid separation accuracy and avoids cross-contamination caused by extractant debris or actinide metal particles entering the crucible.

[0061] Similarly, both the first and second filter screens are preferably made of stainless steel to ensure sufficient mechanical strength and corrosion resistance in a high-temperature molten salt environment, while avoiding the introduction of foreign impurities.

[0062] According to some embodiments of the present invention, the electrolytic refining waste salt purification apparatus 100 includes a plurality of extraction baskets 104.

[0063] By simultaneously setting multiple extraction baskets 104, multiple extraction baskets 104 can be placed into the oxidation precipitation crucible 102 at the same time during the extraction process. This increases the effective contact area between the solid metal extractant and the molten salt in a single extraction process, shortens the time required for the reduction extraction of actinides, and reduces the risk of efficiency decline due to the local depletion of extractant in a single basket.

[0064] When the electrolytic refining waste salt purification device 100 includes multiple extraction baskets 104, the number of baskets can be determined comprehensively based on the molten salt volume, the initial actinide concentration and the target recovery rate, so as to balance the extraction efficiency and the utilization rate of the crucible space.

[0065] See Figure 1 and Figure 2As shown, according to some embodiments of the present invention, the electrolytic refining waste salt purification device 100 further includes: a stirring paddle 106, the stirring end of which is located inside the oxidation precipitation crucible 102, for stirring the molten material inside the oxidation precipitation crucible 102.

[0066] By incorporating the stirring paddle 106, the convection between the molten salt and the solid metal extractant can be accelerated during the extraction stage, shortening the diffusion path of actinide ions and increasing the reduction extraction rate. Furthermore, during the precipitation stage, the oxidizing precipitant and molten salt can be uniformly mixed, avoiding localized supersaturation or rare earth oxide agglomeration, thereby improving precipitation efficiency and particle uniformity.

[0067] Specifically, the outer end of the stirring paddle 106 passes through the sealing end cap 105 and is configured to be connected to the rotary drive component. Its stirring end extends into the molten salt, which can achieve continuous or intermittent stirring while maintaining an inert atmosphere. The speed is adjustable to meet the shear strength requirements of different stages of extraction and precipitation.

[0068] See Figure 1 and Figure 2 As shown, according to some embodiments of the present invention, the electrolytic refining waste salt purification device 100 further includes: a sampler 107, which is disposed through the sealed end cap 105 so that the sampling end of the sampler 107 is located inside the oxidation precipitation crucible 102, for sampling and processing the material in the oxidation precipitation crucible 102.

[0069] By setting up the sampler 107, a small amount of molten salt sample can be extracted while keeping the sealed end cap 105 closed, and the changes in the concentration of actinide or rare earth elements can be monitored in real time. This provides a basis for judging the extraction endpoint and precipitation endpoint, and avoids the risk of inert atmosphere destruction and radioactive aerosol leakage caused by opening the end cap for sampling.

[0070] Understandably, the length of the sampler 107 must ensure that its sampling end is below the lowest liquid level of the agitator 106 and does not interfere with the agitator 106 and the basket, so as to ensure that a representative molten salt sample is obtained and to ensure safe operation.

[0071] See Figure 2 As shown, according to some embodiments of the present invention, the electrolytic refining waste salt purification device 100 further includes: a crucible basket 108, and an oxidation precipitation crucible 102 disposed in the crucible basket 108.

[0072] By setting up the crucible basket 108, the entire crucible can be transported and lifted without directly contacting the outer wall of the oxidation precipitation crucible 102, avoiding collisions between the hot crucible and other parts inside the glove box 200. At the same time, it is convenient to remove the entire crucible out of the heating zone for cooling and demolding after extraction or precipitation, improving operational safety and reducing the impact of heat radiation on personnel and surrounding equipment.

[0073] The crucible basket 108 is preferably made of stainless steel to ensure sufficient mechanical strength and corrosion resistance under high temperature conditions, while avoiding contamination of the molten salt or reaction system.

[0074] See Figure 1 and Figure 2 As shown, according to some embodiments of the present invention, the electrolytic refining waste salt purification device 100 further includes: a leak-proof sleeve 109, which is disposed inside the heater 101, and an oxidation precipitation crucible 102 is disposed inside the leak-proof sleeve 109.

[0075] By setting up a leak-proof sleeve 109, a secondary containment barrier can be formed outside the oxidation precipitation crucible 102. Even if the crucible cracks or molten salt overflows, the molten salt can be confined inside the sleeve, preventing it from flowing directly into the heater 101 or the bottom of the glove box 200, reducing the risk of equipment contamination and facilitating subsequent cleaning and maintenance.

[0076] The leak-proof sleeve 109 is preferably made of stainless steel to withstand high-temperature molten salt corrosion and ensure structural integrity, while also being easy to disassemble, clean, and reuse.

[0077] The electrolytic refining waste salt purification system provided by the present invention is described below. The electrolytic refining waste salt purification system described below can be referred to in correspondence with the electrolytic refining waste salt purification device 100 described above.

[0078] See Figure 5 and Figure 6 As shown, the electrolytic refining waste salt purification system provided in this embodiment of the invention includes: an electrolytic refining waste salt purification device 100, a glove box 200, and a hoisting assembly 300.

[0079] The lifting assembly 300 is used to lift at least one of the oxidation precipitation crucible 102, the filter basket 103, the extraction basket 104, the sealing end cap 105, and the crucible basket 108, and the lifting assembly 300 is located inside the glove box 200.

[0080] The electrolytic refining waste salt purification system provided by this invention, by employing the electrolytic refining waste salt purification device 100 as described in any of the preceding embodiments, can first complete the reduction extraction of actinides in the molten salt state using the extraction basket 104 and remove the entire substance. Then, in the same oxidation precipitation crucible 102, the filter basket 103 is switched to perform rare earth oxidation precipitation. After precipitation, the filter basket 103 is directly lifted to achieve efficient solid-liquid separation of the precipitate and molten salt, and significantly reduce the amount of molten salt entrained. This solves the problems of large size of multi-stage countercurrent extraction equipment, high risk of phase separation, large loss of actinides in the oxidation precipitation method, and the need for subsequent demolding, cutting, and vacuum distillation to recover entrained salt, which leads to a lengthy process, high energy consumption, and large amount of radioactive waste in the prior art.

[0081] Specifically, the electrolytic refining waste salt purification device 100 is used to sequentially complete the insertion and removal of the extraction basket 104 and the lifting and static filtration of the filter basket 103 under the protection of the inert atmosphere provided by the glove box 200, with the help of the hoisting assembly 300. This realizes the closed-loop recovery of actinide, removal of rare earth elements and demolding of salt ingots for decommissioned molten salt, ensuring that radioactive materials do not leak and simplifying the transfer steps.

[0082] See Figure 5 and Figure 6 As shown, as an example, the top of the electrolytic refining waste salt purification device 100 is connected to the circular interface on the bottom plate of the glove box 200 via a flange.

[0083] It should be noted that in the electrolytic refining waste salt purification system, there is at least one electrolytic refining waste salt purification device 100. For example, in this embodiment, the electrolytic refining waste salt purification system includes two electrolytic refining waste salt purification devices 100.

[0084] The glove box 200 provides a closed inert gas environment for the electrolytic refining waste salt purification unit 100 to prevent the molten salt from absorbing moisture and oxidizing, and to prevent the leakage of radioactive aerosols. At the same time, it allows operators to safely complete operations such as loading, sampling, basket replacement and crucible transfer through the glove opening.

[0085] The hoisting assembly 300 is used to lift and move the oxidation precipitation crucible 102, filter basket 103, extraction basket 104, sealing end cap 105 and crucible basket 108 within the inert atmosphere of the glove box 200, and to ensure that the sequential switching of each component between the extraction, precipitation and filtration processes is accurate and reliable.

[0086] As an example, in this embodiment, the lifting assembly 300 includes an adjustable lifting mechanism and multiple linear modules. The adjustable lifting mechanism allows for fine-tuning to accommodate different operational heights, while the linear modules are mounted below the crucible tray to control the lifting and lowering of the oxide precipitation sealing end cap 105 bracket, sampler 107, and camera bracket. Furthermore, a pipeline integration mounting plate is included to integrate and secure related pipeline connections, ensuring that the entire lifting assembly 300 can achieve precise lifting and positioning of all components within the oxide precipitation crucible 102.

[0087] In some embodiments, the electrolytic refining waste salt purification system also includes a camera (not shown in the figure).

[0088] The camera and sampler 107 can share the same location. When not sampling, the camera can be used to monitor the completion of sedimentation and determine whether to stop filtration.

[0089] See Figure 7 and Figure 8As shown, the electrolytic refining waste salt purification method provided in this embodiment of the invention is implemented based on an electrolytic refining waste salt purification system and includes the following steps.

[0090] S710. Place the filter basket 103 into the oxidation precipitation crucible 102, and add a first set weight of electrolytic refining waste salt into the filter basket 103.

[0091] S720. Cover the sealing end cap 105, start the heater 101, and heat the electrolytic refining waste salt at the first set temperature until it is completely melted.

[0092] S730, Remove the sealing end cap 105, and use the lifting assembly 300 to place the extraction basket 104 containing the solid metal extractant into the oxidation precipitation crucible 102, so that the extraction basket 104 is immersed in the molten salt, and then cover the sealing end cap 105 again.

[0093] S740. Start the agitator 106 and maintain the first set speed to keep the molten salt in continuous contact with the solid metal extractant until the concentration of actinides in the molten salt drops to the first set content.

[0094] S750, stop stirring, remove the sealing end cap 105, and use the lifting assembly 300 to remove the extraction basket 104 to complete the recovery of actinides.

[0095] S760. Add an oxidizing precipitant to the oxidizing precipitant crucible 102, so that the amount of oxidizing precipitant added reaches the second set weight.

[0096] S770, Replace the sealing end cap 105, start the agitator 106, and maintain the second set speed until the concentration of rare earth elements in the molten salt drops to the second set content.

[0097] S780. Stop stirring and use the hoisting assembly 300 to lift the filter basket 103 to the set height so that the bottom of the filter basket 103 is higher than the molten salt surface for static filtration.

[0098] S790. After the molten salt has completely flowed into the oxidation precipitation crucible 102 through the first filter hole and the first filter screen, heating is stopped and the mixture is cooled to room temperature to obtain purified salt ingots.

[0099] The electrolytic refining waste salt purification method provided by this invention, under the protection of an inert atmosphere, uses the same oxidation precipitation crucible 102 to sequentially complete the reduction extraction of actinides and the oxidation precipitation of rare earth elements, and then achieves efficient separation of precipitate and molten salt by lifting the filter basket 103. The whole process does not require the transfer of molten salt, which simplifies the operation steps, reduces the amount of molten salt entrainment, improves the recovery rate of actinides and the quality of purified salt, and at the same time reduces energy consumption and the generation of radioactive waste. It solves the problems of complex equipment, long process, loss of actinides and high molten salt entrainment in the prior art.

[0100] The following is a specific example illustrating the method for purifying waste salt from electrolytic refining provided by this invention. (See attached image) Figure 7 and Figure 8 As shown.

[0101] In the high-purity argon atmosphere inside the glove box 200, the heater 101 is fitted onto the outer wall of the oxidation precipitation reactor, the leak-proof sleeve 109 is placed into the reactor cavity, and the polytetrafluoroethylene ring is placed at the reactor opening.

[0102] Then, the oxidation precipitation crucible 102 is placed into the crucible basket 108, and the filter basket 103 is placed inside the oxidation precipitation crucible 102. A first filter screen is set inside the filter basket 103, and 20 kg (first set weight) of LiCl-KCl eutectic salt (electrolytic refining waste salt) containing 1 wt% uranium ions and 0.5 wt% lanthanum ions is added to the filter basket 103.

[0103] After placing the entire crucible basket 108 into the leak-proof sleeve 109 using the hoisting assembly 300 and covering it with the preheating cover, start the heater and heat it to 600°C to 700°C (the first set temperature) to completely melt the salt.

[0104] Remove the preheating cover and fix the extraction basket 104, which is equipped with a second filter and contains 120g of lanthanum metal particles (solid metal extractant), to the integrated oxidation precipitation sealing end cap 105. At the same time, assemble the stirring paddle 106 and the sampler 107, move the sealing end cap 105 above the crucible and seal it, so that the extraction basket 104 is immersed in molten salt. Stir at the set speed, and take samples to monitor the uranium ion concentration during the process. When the uranium ion concentration is ≤0.05wt% (first set content), stop stirring and lift out the extraction basket 104 to complete the recovery of actinide metals.

[0105] Then, 100g of lithium oxide (oxidation precipitant) is added to the molten salt. The sealing end cap 105 is reinstalled and the interface between the filter basket 103 and the sealing end cap 105 is fixed. Stirring continues and samples are taken to monitor the lanthanum concentration. When the lanthanum concentration drops to 0.01wt% (second set content), stirring is stopped. The sealing end cap 105 and the filter basket 103 are raised above the molten salt surface for static filtration. After all the molten salt flows back to the oxidation precipitation crucible 102, heating is stopped. The purified LiCl-KCl salt ingot can be completely removed by cooling to room temperature.

[0106] In some embodiments, the method for purifying waste salt from electrolytic refining can also be implemented as follows.

[0107] The filter basket 103 and extraction basket 104 are simultaneously hung on the sealed end cap 105 and operated together. When the filter basket 103 and extraction basket 104 are placed in the molten salt, only the solid metal extractant (such as lanthanum metal) is placed in the extraction basket 104. After the actinide metals in the molten salt are extracted, the extraction basket 104 is lifted and removed first. Then, an oxidant is added to the filter basket 103. After precipitation is complete, the oxidizing filter basket 103 is then lifted.

[0108] 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 of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for purifying waste salt from electrolytic refining, characterized in that, include: heater; An oxidation precipitation crucible is disposed inside the heater; A filter basket is used to hold electrolytic refining waste salt. The filter basket is located inside the oxidation precipitation crucible. The filter basket is provided with a first filter hole to connect the internal space of the filter basket with the oxidation precipitation crucible. An extraction basket is used to hold a solid metal extractant. The extraction basket is placed inside the oxidation precipitation crucible. The extraction basket is provided with a second filter hole to connect the internal space of the extraction basket with the oxidation precipitation crucible. A sealing end cap is provided at the top opening of the oxidation precipitation crucible.

2. The electrolytic refining waste salt purification device according to claim 1, characterized in that, The filter basket is equipped with a first filter screen, and the first filter screen is equipped with a third filter hole, the diameter of the third filter hole being smaller than the diameter of the first filter hole. And / or, the extraction basket is provided with a second filter screen, the second filter screen is provided with a fourth filter hole, the diameter of the fourth filter hole is smaller than the diameter of the second filter hole.

3. The electrolytic refining waste salt purification device according to claim 1, characterized in that, It includes multiple extraction baskets.

4. The electrolytic refining waste salt purification device according to claim 1, characterized in that, Also includes: A stirring paddle, the stirring end of which is located inside the oxidation precipitation crucible, is used to stir the molten material inside the oxidation precipitation crucible.

5. The electrolytic refining waste salt purification device according to claim 1, characterized in that, Also includes: A sampler is inserted through the sealed end cap so that the sampling end of the sampler is located inside the oxidation precipitation crucible, for sampling and processing the material in the oxidation precipitation crucible.

6. The electrolytic refining waste salt purification device according to claim 1, characterized in that, Also includes: A crucible basket, wherein the oxidation precipitation crucible is disposed in the crucible basket.

7. The electrolytic refining waste salt purification device according to claim 1, characterized in that, Also includes: A leak-proof sleeve is provided inside the heater, and the oxidation precipitation crucible is provided inside the leak-proof sleeve.

8. The electrolytic refining waste salt purification apparatus according to any one of claims 1 to 7, characterized in that, The oxidation precipitation crucible is made of graphite material; And / or, the filter basket is made of stainless steel; And / or, the extraction basket is made of stainless steel.

9. A purification system for waste salt from electrolytic refining, characterized in that, include: The electrolytic refining waste salt purification apparatus as described in any one of claims 1 to 8; Glove box; A hoisting assembly for hoisting at least one of an oxidation precipitation crucible, a filter basket, an extraction basket, a sealing end cap, and a crucible basket, wherein the hoisting assembly is located inside the glove box.

10. A method for purifying waste salt from electrolytic refining, characterized in that, Based on the electrolytic refining waste salt purification system as described in claim 9, including: Place the filter basket in the oxidation precipitation crucible, and add the first set weight of electrolytic refining waste salt into the filter basket; Cover the sealed end cap, start the heater, and heat the electrolytic refining waste salt at the first set temperature until it is completely melted; Remove the sealed end cap, and use the lifting assembly to place the extraction basket containing the solid metal extractant into the oxidation precipitation crucible, so that the extraction basket is immersed in the molten salt, and then replace the sealed end cap. Start the agitator and maintain the first set speed to keep the molten salt in continuous contact with the solid metal extractant until the concentration of actinides in the molten salt drops to the first set content; Stop stirring, remove the sealed end cap, and use the lifting assembly to remove the extraction basket to complete the recovery of actinides; Add an oxidizing precipitant into the oxidizing precipitant crucible until the amount of oxidizing precipitant added reaches the second set weight; Replace the sealing end cap, start the stirring paddle, and maintain the second set speed until the concentration of rare earth elements in the molten salt drops to the second set content; Stop stirring and use the hoisting assembly to lift the filter basket to the set height, so that the bottom of the filter basket is higher than the molten salt surface, for static filtration; After the molten salt has completely flowed into the oxidation precipitation crucible through the first filter hole and the first filter screen, heating is stopped, and the crucible is cooled to room temperature to obtain purified salt ingots.

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