Multi-element fluorinated molten salt uranium recovery device and method

Abstract

The invention provides a multi-element fluorinated molten salt uranium recovery device and method.The device comprises a gas pretreatment unit, a bubbling reaction unit, a product collection unit and a tail gas treatment unit which are sequentially connected through gas pipelines; by means of the device and method, a whole set of multi-element fluorinated molten salt uranium recovery and highly toxic and highly corrosive tail gas treatment can be safely and efficiently completed, and technical support and safety guarantee are provided for recovery of uranium in multi-element fluorinated waste molten salt generated in the operation process of a fourth-generation liquid thorium-based molten salt reactor. According to the device disclosed by the invention, the gas preheater, the gas distributor, the baffle plate, the two-stage cooling jacket and other corollary equipment are creatively arranged, so that full proceeding of a fluorination reaction and thorough condensation of uranium hexafluoride gas can be ensured, and the collection efficiency of uranium hexafluoride is improved to the greatest extent. In addition, by arranging a kettle cover water cooling ring, a detachable gas inlet pipe and other components, the convenience and safety of the multi-element fluorinated molten salt uranium recovery operation are further improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of radioactive waste treatment, and particularly relates to a multi-element fluorinated molten salt uranium recovery device and method. BACKGROUND

[0002] The molten salt reactor is an important fuel reactor type of the fourth generation reactor, which is a liquid fuel reactor formed by melting nuclear fuel in a liquid fluoride salt coolant. At this time, the liquid fluoride salt is used as both a coolant and a carrier of nuclear fuel. When the coolant flows out of the reactor core, online or offline separation of isotopes can be achieved by using dry separation technology. Dry separation technology can be divided into volatilization method and metallurgical method according to different technical principles, and fluorination volatilization method is the most commonly used and most fully researched volatilization method in the volatilization method. As an important technology in dry separation technology, fluorination volatilization technology converts low-valence uranium fluoride into high-valence fluoride UF6 by fluorine gas, and realizes the separation and recovery of uranium by using the low boiling point and easy volatilization characteristics of UF6. Therefore, uranium recovery by fluorination volatilization technology on the molten salt system is expected to realize the nuclear fuel cycle of the molten salt reactor. The fluorination reaction device can be completed by fluorination reactor, but the fluorination reactor used in the prior art generally has the problems of salt cooling leading to blockage of the gas inlet pipe after the reaction is completed, and the gas inlet pipe is fixed in the solidified molten salt and is difficult to take out. Moreover, there is no report on a complete set of special multi-element fluorinated molten salt uranium recovery device in the prior art. In order to realize the recovery of uranium in the multi-element fluorinated waste molten salt generated in the operation process of the liquid thorium-based molten salt reactor, it is urgent to propose a multi-element fluorinated molten salt uranium recovery device, which not only includes the main reaction device part, but also includes the front-end gas pretreatment unit, the rear-end reaction product collection unit and the tail gas treatment unit, so as to efficiently complete the recovery of uranium in the multi-element fluorinated molten salt and the treatment of the remaining reaction gas. SUMMARY

[0003] In order to solve the above technical problems, the application provides a multi-element fluorinated molten salt uranium recovery device and method, which can realize the recovery of uranium in the multi-element fluorinated molten salt generated in the operation process of the liquid thorium-based molten salt reactor and the treatment of the remaining gas.

[0004] In a first aspect, the application discloses a multi-element fluorinated molten salt uranium recovery device, which comprises a gas pretreatment unit, a bubbling reaction unit, a product collection unit and a tail gas treatment unit connected in sequence through a gas pipeline. The gas pretreatment unit comprises a gas preheater and a gas controller. The bubbling reaction unit comprises a heating furnace, a cover, a reaction container and a first cooling liquid circulating machine. The product collection unit comprises a cylindrical sleeve, a product collection tank and a second cooling liquid circulating machine. The tail gas treatment unit comprises a charcoal combustion furnace and an alkali absorption tank.

[0005] Further, the gas preheater is used to heat the reaction gas introduced into the bubble reaction unit; the gas controller includes a flow meter and a gas valve for controlling the flow and start-stop of the reaction gas introduced into the bubble reaction unit.

[0006] Further, the reaction container is externally sleeved with a heating furnace for heating the reaction container; the reaction container and the kettle cover are extruded and sealed by a fluorine rubber ring, and a water cooling ring is arranged between the reaction container and the kettle cover for reducing the temperature of the fluorine rubber ring; a detachable bubble gas inlet pipe and a gas outlet are arranged on the kettle cover, the bubble gas inlet pipe extends into the reaction container to guide the reaction gas into the reaction container, and the reacted gas overflows from the gas outlet; a gas distributor is arranged at the bottom end of the bubble gas inlet pipe.

[0007] Further, the outside of the gas pipeline connected to the gas outlet on the kettle cover is externally sleeved with a first cooling jacket for reducing the temperature of the gas overflowing from the reaction container; the first cooling liquid circulating machine is used to deliver cooling water to the first cooling jacket and the water cooling ring.

[0008] Further, the top of the cylindrical sleeve is provided with a gas inlet and a gas outlet, the gas enters the cylindrical sleeve from the gas inlet, falls into the product collection tank movably connected to the bottom of the cylindrical sleeve after being condensed into solid in the cylindrical sleeve, and the remaining tail gas overflows from the gas outlet; a second cooling jacket is arranged outside the cylindrical sleeve, and the second cooling liquid circulating machine is used to deliver cooling liquid to the second cooling jacket to condense the gas product flowing in the cylindrical sleeve; a baffle is arranged inside the cylindrical sleeve, and the gas inlet and the gas outlet are respectively located on the two sides of the baffle to realize U-shaped flow of the gas in the cylindrical sleeve to ensure sufficient condensation.

[0009] Further, two valves are arranged at the connection between the cylindrical sleeve and the product collection tank to seal the cylindrical sleeve and the product collection tank respectively to ensure that the cylindrical sleeve and the product collection tank remain sealed after being separated.

[0010] Further, the charcoal combustion furnace includes a furnace body, a charcoal placer located inside the furnace body, and an ash tank connected to the bottom of the furnace body; the bottom of the furnace body is provided with a gas inlet, and the top of the furnace body is provided with a gas outlet, the tail gas enters the furnace body through the gas inlet and overflows from the furnace body through the gas outlet; the upper part of the furnace body is provided with a charcoal feeding port for feeding charcoal into the furnace body, and the charcoal falls to the charcoal placer after entering the furnace body; the charcoal placer is located between the gas inlet and the gas outlet; and the ash tank is used to collect the charcoal ash generated by the reaction of the tail gas and the charcoal.

[0011] Further, the alkali liquid absorption tank is formed by connecting multiple absorption tanks in series, and the tail gas is sequentially absorbed by the alkali liquid in the multiple absorption tanks and then discharged from the alkali liquid absorption tank.

[0012] Secondly, this invention also discloses a method for recovering uranium from multi-component fluoride molten salt, comprising the following steps: The multi-component fluorinated molten salt is heated to a liquid state inside a sealed reaction vessel. A mixture of fluorine gas and inert gas, or a mixture of nitrogen trifluoride gas and inert gas, is heated to a temperature higher than the melting point of the multi-component fluoride molten salt and then introduced into the reaction vessel in a bubbling manner to react with uranium tetrafluoride in the multi-component fluoride molten salt to generate uranium hexafluoride. The product, uranium hexafluoride, is released as a gas from the reaction vessel along with the tail gas and enters the product collection unit. In the product collection unit, the tail gas is cooled until the uranium hexafluoride gas sublimates into a solid, and the solid uranium hexafluoride is collected, thus completing the recovery of uranium from the multi-component fluoride molten salt.

[0013] Furthermore, the remaining tail gas after uranium recovery is treated by guiding it to a charcoal combustion furnace. The unreacted residual fluorine gas in the tail gas reacts with the charcoal to generate carbon tetrafluoride, thereby removing the fluorine gas from the tail gas.

[0014] This application provides a multi-component fluorinated molten salt uranium recovery apparatus and method for recovering uranium from multi-component fluorinated molten salt generated during the operation of a liquid thorium-based molten salt reactor, and for effectively treating the remaining gas. Compared with the prior art, this application has at least the following advantages: (1) This application proposes for the first time a complete device and method for the recovery of uranium from multi-component fluorinated molten salt. The device of this application includes not only the main reaction device, but also the front-end gas pretreatment unit, the back-end reaction product collection unit and the tail gas treatment unit. It can safely and efficiently complete the recovery of uranium from multi-component fluorinated molten salt and the treatment of highly toxic and corrosive tail gas, providing technical support for the recovery of uranium from multi-component fluorinated waste molten salt generated during the operation of the fourth-generation liquid thorium-based molten salt reactor.

[0015] (2) This application preheats the reaction gas to the melting point temperature of the multi-component fluorinated molten salt by passing the reaction gas through a gas preheater before introducing the reaction gas into the reaction vessel, thereby reducing the heat loss of the unpreheated reaction gas after entering the reaction vessel, avoiding the temperature drop of the multi-component fluorinated molten salt, which would lead to an increase in viscosity and thus affect the occurrence of the fluorination reaction and the uranium recovery effect, and ensuring the full progress of the fluorination reaction to the maximum extent.

[0016] (3) This application provides a first cooling jacket outside the gas pipeline at the gas outlet of the reaction vessel and a second cooling jacket outside the cylindrical sleeve. The two-stage cooling system can ensure that the uranium hexafluoride gas is completely condensed into a solid in the product collection unit, thereby maximizing the collection efficiency of uranium hexafluoride.

[0017] (4) By setting a gas distributor at the bottom of the bubbling inlet pipe, this application can maximize the contact area between the reaction gas and the multi-component fluorinated molten salt, ensure the full progress of the fluorination reaction, and improve the recovery efficiency of uranium hexafluoride.

[0018] (5) This application creatively sets a water-cooling ring between the reaction vessel and the lid, which can effectively extend the service life of the sealing material under high temperature conditions, thereby ensuring the overall sealing performance of the device and ensuring the safety of the multi-component fluorinated molten salt uranium recovery operation.

[0019] (6) The bubbling gas inlet pipe on the reactor lid of this application is set as a detachable gas inlet pipe. The fixed gas inlet pipe of the existing reaction vessel is creatively adjusted to a detachable gas inlet pipe. After the multi-component fluoride molten salt uranium recovery reaction is completed, the gas inlet pipe is disassembled and raised above the liquid molten salt in advance while the molten salt is in a liquid state. This avoids the gas inlet pipe being solidified in the molten salt after the molten salt cools down, and avoids the subsequent reactor lid being difficult to open and disassemble, as well as the gas inlet pipe being blocked. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the multi-component fluorinated molten salt uranium recovery device of the present invention.

[0022] Reference numerals: 1. Gas preheater; 2. Mass flow meter; 3. Gas valve; 4. Heating furnace; 5. Kettle cover; 6. Reaction vessel; 7. Cylindrical sleeve; 8. Product collection tank; 9. Charcoal combustion furnace; 10. Alkali absorption tank; 11. Bubbling gas inlet pipe; 12. Gas distributor; 13. First cooling jacket; 14. Second cooling jacket; 15. Baffle; 16. Valve; 17. Valve; 18. Furnace body; 19. Charcoal holder; 20. Ash jar; 21. Charcoal feeding port. Detailed Implementation

[0023] The technical solutions of the embodiments of this application 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 application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0024] Unless otherwise specified, the preferred embodiments of the present invention can be freely combined as needed. Those skilled in the art will understand that the data and various parameters described in the embodiments are merely exemplary and do not constitute a limitation of the present invention. The devices used in the following embodiments are all devices known in the art, and all devices used in the present invention can be obtained commercially.

[0025] Example 1 This invention provides a multi-component fluoride molten salt uranium recovery device, comprising a gas pretreatment unit, a bubbling reaction unit, a product collection unit, and a tail gas treatment unit connected in sequence via gas pipelines; The gas pretreatment unit includes a gas preheater 1 and a gas controller; The bubbling reaction unit includes a heating furnace 4, a kettle lid 5, a reaction vessel 6, and a first coolant circulator; The product collection unit includes a cylindrical sleeve 7, a product collection tank 8, and a second coolant circulator; The exhaust gas treatment unit includes a charcoal combustion furnace 9 and an alkaline absorption tank 10.

[0026] The gas preheater 1 described in this invention is used to heat the reaction gas introduced into the bubbling reaction unit. The maximum operating temperature of the gas preheater 1 should be greater than the melting temperature of the multi-component fluorinated molten salt in the reaction vessel 6. For the multi-component fluorinated waste molten salt generated during the operation of the liquid thorium-based molten salt reactor, the maximum operating temperature of the gas preheater 1 can reach 800℃, and the allowable gas flow rate is 0~5L / min. This invention preheats the reaction gas to the melting point temperature of the multi-component fluorinated molten salt by passing it through the gas preheater, which can significantly reduce the heat loss of the unpreheated reaction gas after it enters the reaction vessel, and avoid the temperature drop of the multi-component fluorinated molten salt leading to an increase in viscosity, thereby affecting the fluorination reaction and uranium recovery. The gas controller includes a flow meter 2 and a gas valve 3, used to control the flow rate and start / stop of the reaction gas introduced into the bubbling reaction unit. Depending on the type of reaction gas used, multiple inlet pipelines can be set up, and multiple sets of flow meters and gas valves can be configured. For example, the reaction gas used in this invention is a mixture of fluorine gas and inert gas, or a mixture of nitrogen trifluoride gas and inert gas. Therefore, this invention can be equipped with two inlet pipelines, each with a mass flow meter and a gas valve.

[0027] The reaction vessel 6 of this invention is externally fitted with a heating furnace 4 for heating the reaction vessel 6. The heating method of the heating furnace can be resistance heating, and the maximum heating temperature should be greater than the melting temperature of the multi-component fluorinated molten salt inside the reaction vessel 6. For the multi-component fluorinated waste molten salt generated during the operation of the liquid thorium-based molten salt reactor, the maximum heating temperature of the heating furnace 4 can reach 800℃. The reaction vessel 6 and the vessel cover 5 are sealed by compression with fluororubber rings. A water-cooling ring is provided between the reaction vessel 6 and the vessel cover 5 to reduce the temperature of the fluororubber ring and prevent high-temperature aging of the fluororubber ring. The water-cooling ring can effectively extend the service life of the fluororubber ring under high-temperature conditions, thereby ensuring the overall sealing performance of the bubbling reaction unit and ensuring the safety of the multi-component fluorinated molten salt uranium recovery operation. The vessel cover 5 is provided with a detachable bubbling gas inlet pipe 11 and a gas outlet. The bubbling gas inlet pipe 11 extends into the reaction vessel 6 to guide the reaction gas into the reaction vessel 6, and the gas after the reaction overflows from the gas outlet.

[0028] This invention creatively transforms the conventional fixed gas inlet pipe on the reactor lid into a detachable gas inlet pipe, greatly facilitating actual recovery operations. After the uranium recovery reaction of the multi-component fluoride molten salt is completed, the bubbling gas inlet pipe can be disassembled and pulled above the liquid molten salt in advance, thus preventing the gas inlet pipe from solidifying inside the molten salt after cooling. This avoids difficulties in opening and disassembling the reactor lid and prevents gas inlet pipe blockage. A gas distributor 12 is provided at the bottom of the bubbling gas inlet pipe 11, which maximizes the contact area between the reaction gas and the molten multi-component fluoride molten salt, ensuring a complete fluorination reaction and improving the recovery efficiency of uranium hexafluoride. Furthermore, temperature and pressure sensors can be installed on the reactor lid 5 to monitor the temperature and pressure inside the reaction vessel 6. To prevent overheating due to equipment malfunctions, an over-temperature feedback interlock module can be equipped on the heating furnace 4, automatically cutting off power in case of overheating to prevent equipment overheating.

[0029] This invention features a first cooling jacket 13 fitted around the gas pipeline connecting to the gas outlet on the reactor lid 5. This jacket reduces the temperature of the gas overflowing from the reaction vessel 6. A first coolant circulator can supply cooling water to the cooling jacket 13 on the gas outlet pipeline above the reactor lid and to the water-cooling ring at the top of the reaction vessel 6 via a three-way valve. By installing the first cooling jacket 13 outside the gas pipeline at the gas outlet of the reaction vessel 6, this invention ensures that uranium hexafluoride gas is completely condensed into a solid in the subsequent product collection unit, thereby maximizing the collection efficiency of uranium hexafluoride. The reaction vessel 6 used in this invention is preferably made of a material resistant to corrosive gases such as fluorine and hydrogen fluoride, including but not limited to metals such as Inconel 625 and Hastelloy.

[0030] In the product collection unit of this invention, the cylindrical sleeve 7 has an inlet and an outlet at its top. Gas enters the cylindrical sleeve 7 through the inlet, condenses into a solid inside the sleeve, and falls into the product collection tank 8, which is movably connected to the bottom of the sleeve 7. Remaining exhaust gas overflows through the outlet. A second cooling jacket 14 is provided outside the cylindrical sleeve 7. A second coolant circulator is used to supply coolant to the second cooling jacket 14 to condense the gaseous products flowing inside the cylindrical sleeve 7. A baffle 15 is provided inside the cylindrical sleeve 7. The inlet and outlet are located on opposite sides of the baffle 15. The baffle 15 allows the gas inside the cylindrical sleeve to flow around the baffle in a U-shape, thereby allowing the product gas to stay in the cylindrical sleeve 7 for a longer time and to undergo a longer heat exchange with the second cooling jacket 14. This ensures that the product gas can be completely condensed into a solid inside the cylindrical sleeve 7, thus maximizing the collection efficiency of uranium hexafluoride. The cylindrical sleeve 7 and the product collection tank 8 of the present invention can be connected by a quick-connect flange. Two valves 16 and 17 are provided at the connection between the cylindrical sleeve 7 and the product collection tank 8, which are used to seal the cylindrical sleeve 7 and the product collection tank 8 respectively, so as to ensure that the cylindrical sleeve 7 and the product collection tank 8 can remain sealed after separation.

[0031] In the charcoal combustion furnace 9 of the present invention, the charcoal combustion furnace 9 includes a furnace body 18, a charcoal holder 19 located inside the furnace body 18, and an ash container 20 connected to the bottom of the furnace body 18. The furnace body 18 has an air inlet at the bottom and an air outlet at the top. Exhaust gas enters the furnace body 18 through the air inlet and overflows from the furnace body 18 through the air outlet. A charcoal feeding port 21 is provided at the upper part of the furnace body 18 for feeding charcoal into the furnace body 18. After entering the furnace body 18, the charcoal falls and settles on the charcoal holder 19, which is located between the air inlet and the air outlet, thereby reacting chemically with the fluorine gas in the flowing exhaust gas. The ash container 20 is located below the air inlet to collect the charcoal ash produced by the reaction between the exhaust gas and the charcoal. For convenient observation of the charcoal state, a reaction observation port can also be provided on the furnace body 18. To prevent the exothermic reaction from burning through the charcoal holder 19, the charcoal holder can be composed of multiple hollow tubes arranged together, and preferably, cooling water is circulated through the hollow tubes to prevent the charcoal holder 19 from overheating. To enhance the alkali absorption effect, the alkali absorption tank 10 of the present invention can be composed of multiple absorption tanks connected in series to form a multi-stage absorption tank. The alkali solution in the absorption tank includes, but is not limited to, potassium carbonate, sodium carbonate, potassium hydroxide, and sodium hydroxide solutions, as long as it can absorb acidic gases such as fluorine gas. The exhaust gas is discharged from the alkali absorption tank after being absorbed by the alkali solution in the multi-stage absorption tank in sequence.

[0032] Therefore, this invention designs a complete device for the recovery of uranium from multi-component fluorinated molten salt. The device includes not only the main reaction unit, but also a front-end gas pretreatment unit, a back-end reaction product collection unit, and a tail gas treatment unit. It can safely and efficiently complete the recovery of uranium from multi-component fluorinated molten salt and the treatment of residual reaction gases, providing technical support for the recovery of uranium from multi-component fluorinated waste molten salt generated during the operation of fourth-generation liquid thorium-based molten salt reactors.

[0033] Example 2 This invention provides a method for recovering uranium from multi-component fluoride molten salts, comprising the following steps: The crucible containing the multi-component fluorinated molten salt is placed inside the reaction vessel 6. The lid 5 and the reaction vessel 6 are sealed by a fluororubber ring compression and bolts. Preferably, the entire device can be purged with dry inert gas to remove air and water from the reaction device. Turn on the heating furnace 4 and heat the multi-component fluorinated molten salt in the sealed reaction vessel 6 to ensure that the multi-component fluorinated molten salt is in a liquid state; the heating temperature and holding time should be sufficient to ensure that the multi-component fluorinated molten salt is in a liquid state. Preferably, the heating temperature of the multi-component fluorinated molten salt is 400~750℃ and the heating holding time is 1~5h. The reaction gas, either a fluorine / inert gas mixture or a nitrogen trifluoride / inert gas mixture, is heated to a temperature higher than the melting point of the multi-component fluoride molten salt by a gas preheater 1, and then introduced into the reaction vessel 6 in a bubbling manner to react with uranium tetrafluoride in the multi-component fluoride molten salt to generate uranium hexafluoride; similarly, the heating temperature can reach the melting temperature of the multi-component fluoride molten salt. Preferably, the reaction gas is preheated to 400~750°C by a gas preheater. The product uranium hexafluoride is discharged from the reaction vessel 6 in gaseous form along with the tail gas and enters the product collection unit. Before entering the product collection unit, the tail gas is cooled for the first time by heat exchange through the first cooling jacket 13 outside the gas pipeline of the gas outlet of the reaction vessel 6. The tail gas temperature is preferably reduced to 50~150℃. After the exhaust gas enters the product collection unit, it undergoes heat exchange in the second cooling jacket 14 outside the cylindrical sleeve 7, which condenses the uranium hexafluoride gas in the exhaust gas into a solid and falls into the product collection tank 8 at the bottom of the cylindrical sleeve 7. After the fluorination reaction in reaction vessel 6 is completed, purge the entire apparatus with inert gas along the gas path until the highly toxic and corrosive gases are completely removed from reaction vessel 6 and cylindrical sleeve 7. Close gas preheater 1 and furnace 4, and disassemble and lift the bubbling inlet pipe 11 above the liquid molten salt. Close the two valves 16 and 17 at the connection between cylindrical sleeve 7 and product collection tank 8, disassemble the quick-connect flange, and remove the product collection tank 8 containing solid uranium hexafluoride in a sealed state. At this time, cylindrical sleeve 7 also remains sealed, completing the recovery of uranium from the multi-component fluorinated molten salt.

[0034] Under the purging action of inert gas, the tail gas is guided to the charcoal combustion furnace 9 to treat the remaining tail gas after uranium recovery. After entering the charcoal combustion furnace 9, the unreacted residual fluorine gas in the tail gas reacts chemically with the charcoal on the charcoal holder 19 in the furnace body 18 to generate carbon tetrafluoride, thus removing the fluorine gas from the tail gas. The charcoal ash falls into the ash container 20 at the bottom of the furnace body 18. After the remaining tail gas treatment is completed, the tail gas reacting with the charcoal is guided to the multi-stage alkaline absorption tank 10 connected in series. The remaining corrosive gases in the tail gas react chemically with the alkaline solution in the multi-stage alkaline absorption tank 10 in sequence, further absorbing the corrosive tail gas. At this point, all tail gas treatment processes are completed, and the treated tail gas is discharged into the atmosphere. The inert gas valve is closed, purging is stopped, and the ash container 20 is removed from below the furnace body 18 in a sealed state, completing the multi-component fluoride molten salt uranium recovery and tail gas treatment.

[0035] In summary, this invention creatively proposes a complete device and method for recovering uranium from multi-component fluorinated molten salts. The device includes not only the main reaction unit but also a front-end gas pretreatment unit, a back-end reaction product collection unit, and a tail gas treatment unit. Using this device and method, uranium recovery from multi-component fluorinated molten salts and the treatment of highly toxic and corrosive tail gases can be achieved safely and efficiently, providing technical support and safety assurance for the recovery of uranium from multi-component fluorinated waste molten salts generated during the operation of fourth-generation liquid thorium-based molten salt reactors. This invention, through the creative design of a gas preheater, gas distributor, baffles, and a two-stage cooling jacket, ensures the full progress of the fluorination reaction and the complete condensation of uranium hexafluoride gas, thereby maximizing the collection efficiency of uranium hexafluoride. Furthermore, the invention further improves the convenience and safety of uranium recovery operations from multi-component fluorinated molten salts by incorporating components such as a water-cooled ring on the reactor lid and a detachable gas inlet pipe.

[0036] The materials and equipment used in this invention are all commercially available. The above description is only a preferred embodiment of the present invention and is not intended to limit the 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.

Claims

1. A multi-component fluoride molten salt uranium recovery device, characterized in that, It includes a gas pretreatment unit, a bubbling reaction unit, a product collection unit, and an exhaust gas treatment unit, which are connected in sequence via gas pipelines. The gas pretreatment unit includes a gas preheater and a gas controller; The bubbling reaction unit includes a heating furnace, a kettle lid, a reaction vessel, and a first coolant circulator; The product collection unit includes a cylindrical sleeve, a product collection tank, and a second coolant circulator; The exhaust gas treatment unit includes a charcoal combustion furnace and an alkaline absorption tank.

2. The multi-component fluoride molten salt uranium recovery device according to claim 1, characterized in that, The gas preheater is used to heat the reaction gas introduced into the bubbling reaction unit; the gas controller includes a flow meter and a gas valve, used to control the flow rate and start / stop of the reaction gas introduced into the bubbling reaction unit.

3. The multi-component fluoride molten salt uranium recovery device according to claim 1, characterized in that, The reaction vessel is fitted with a heating furnace for heating the reaction vessel; the reaction vessel and the vessel lid are sealed by compression with a fluororubber ring, and a water-cooling ring is provided between the reaction vessel and the vessel lid to reduce the temperature of the fluororubber ring; the vessel lid is provided with a detachable bubbling gas inlet pipe and a gas outlet, the bubbling gas inlet pipe extends into the reaction vessel to guide the reaction gas into the reaction vessel, and the gas after the reaction overflows from the gas outlet; a gas distributor is provided at the bottom end of the bubbling gas inlet pipe.

4. The multi-component fluoride molten salt uranium recovery device according to claim 3, characterized in that, A first cooling jacket is fitted around the gas pipeline connecting to the gas outlet on the vessel lid to reduce the temperature of the gas overflowing from the reaction vessel; the first coolant circulator is used to supply cooling water to the first cooling jacket and the water cooling ring.

5. The multi-component fluoride molten salt uranium recovery device according to claim 1, characterized in that, The cylindrical sleeve is provided with an air inlet and an air outlet at the top. Gas enters the cylindrical sleeve from the air inlet, and after being condensed into a solid inside the cylindrical sleeve, it falls into a product collection tank that is movably connected to the bottom of the cylindrical sleeve. The remaining tail gas overflows from the air outlet. A second cooling jacket is provided outside the cylindrical sleeve. The second coolant circulator is used to deliver coolant to the second cooling jacket to condense the gas products flowing inside the cylindrical sleeve. A baffle is provided inside the cylindrical sleeve. The air inlet and air outlet are located on both sides of the baffle to realize the U-shaped flow of gas inside the cylindrical sleeve to ensure sufficient condensation.

6. The multi-component fluorinated molten salt uranium recovery device according to claim 5, characterized in that, Two valves are installed at the connection between the cylindrical sleeve and the product collection tank, which are used to seal the cylindrical sleeve and the product collection tank respectively, so as to ensure that the cylindrical sleeve and the product collection tank remain sealed after separation.

7. The multi-component fluoride molten salt uranium recovery device according to claim 1, characterized in that, The charcoal combustion furnace includes a furnace body, a charcoal holder located inside the furnace body, and an ash container connected to the bottom of the furnace body. The furnace body has an air inlet at the bottom and an air outlet at the top. Exhaust gas enters the furnace body through the air inlet and overflows from the furnace body through the air outlet. The upper part of the furnace body has a charcoal feeding port for feeding charcoal into the furnace body. After entering the furnace body, the charcoal falls into the charcoal holder. The charcoal holder is located between the air inlet and the air outlet. The ash container is used to collect the charcoal ash produced by the reaction of exhaust gas and charcoal.

8. The multi-component fluoride molten salt uranium recovery device according to claim 1, characterized in that, The alkaline absorption tank is composed of multiple absorption tanks connected in series. The exhaust gas is absorbed by the alkaline solution in the multiple absorption tanks in sequence and then discharged from the alkaline absorption tank.

9. A method for recovering uranium from multi-component fluorinated molten salt, characterized in that, The method includes the following steps: The multi-component fluorinated molten salt is heated to a liquid state inside a sealed reaction vessel. A mixture of fluorine gas and inert gas, or a mixture of nitrogen trifluoride gas and inert gas, is heated to a temperature higher than the melting point of the multi-component fluoride molten salt and then introduced into the reaction vessel in a bubbling manner to react with uranium tetrafluoride in the multi-component fluoride molten salt to generate uranium hexafluoride. The product, uranium hexafluoride, is released as a gas from the reaction vessel along with the tail gas and enters the product collection unit. In the product collection unit, the tail gas is cooled until the uranium hexafluoride gas sublimates into a solid, and the solid uranium hexafluoride is collected, thus completing the recovery of uranium from the multi-component fluoride molten salt.

10. The method for recovering uranium from multi-component fluorinated molten salts according to claim 9, characterized in that, The residual tail gas after uranium recovery is treated by directing it to a charcoal combustion furnace. Unreacted residual fluorine in the tail gas reacts with the charcoal to generate carbon tetrafluoride, thereby removing the fluorine from the tail gas.

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