Device and method for preparing UF4
By designing a uranium tetrafluoride preparation device combining the characteristics of centrifugal spray drying and horizontal fluorination reactors, uranium tetrafluoride is directly prepared in the same reactor, which solves the problems of large material input and large nuclear safety pressure in the existing process, and achieves safe and efficient preparation of small amounts of high abundance UF4.
Patent Information
- Application Number
- CN202411739979.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-29
- Publication Date
- 2025-04-01
AI Technical Summary
In the existing UF4 preparation process, excessive dry process equipment leads to excessive material investment and serious waste, while the wet process faces huge safety pressure in the nuclear boundary, making it difficult to meet the needs of a small amount of high-abundance UF4 preparation in scientific research projects.
A uranium tetrafluoride preparation device combining centrifugal spray drying and horizontal fluorination reactor was designed. Uranium tetrafluoride was prepared directly in the same reactor through extraction, strip purification, membrane evaporation and concentration, spray drying and fluorination reduction reactions.
It effectively solves the problems of large input of dry process materials and high critical safety pressure of wet process cores in the preparation of small amounts of high abundance UF4, and provides a safe and efficient preparation device and operating process method for scientific research and production.
Smart Images
Figure CN119733453A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of nuclear power, and in particular relates to a device and a method for preparing UF4. Background Art
[0002] The UF4 preparation technologies that have been industrially applied at home and abroad mainly include uranium dioxide hydrofluorination process, uranium hexafluoride hydrogen reduction process, wet uranium dioxide complexation method and uranium hexafluoride hydrolysis catalytic precipitation method. These processes have their own advantages, but in actual production and scientific research practice, it is often necessary to prepare a small amount of high-abundance UF4. The above-mentioned dry process equipment is too large, resulting in excessive material input and material waste, and the wet process faces huge nuclear safety pressure. Therefore, it is necessary to develop a small-scale UF4 preparation device to meet the needs of small-scale UF4 preparation in scientific research projects. Summary of the invention
[0003] In order to overcome the problems existing in the related art, a device and method for preparing UF4 are provided.
[0004] According to one aspect of an embodiment of the present disclosure, there is provided a device for preparing UF4, the device comprising: a nozzle, a dryer, a separator, a reactor, a heating body and a discharge port;
[0005] After the uranyl nitrate solution is extracted and stripped for purification, it is evaporated and concentrated by a membrane evaporator to obtain a uranyl nitrate liquid. The uranyl nitrate liquid is delivered to a nozzle by a metering pump, preheated at the nozzle, atomized by nitrogen, and then sprayed into a dryer. After being dried in the dryer to form uranyl nitrate crystals, it is driven by a spiral feed port and delivered to a reactor.
[0006] The heating body is wrapped around the outside of the reactor and is used to heat the reactor at a preset temperature. Ammonium fluoride gas, as a fluorination reduction medium, enters the reactor after being preheated to a specified temperature. Uranyl nitrate crystals are reduced to form uranium dioxide in the reactor and are fluorinated to form uranium tetrafluoride. The product uranium tetrafluoride is delivered to the product packaging chamber through the discharge port on the side wall of the reactor by a spiral with a cooling jacket and loaded into the product container.
[0007] In a possible implementation, the separator is connected to the dryer and the reactor respectively, and nitrogen, excess hydrogen fluoride, ammonia, gases generated by the reaction and uranium fluoride powder entrained by water vapor escape, are filtered through a sintered stainless steel microporous filter in a diffusion cyclone separator, and then washed in a washing tower and discharged into the atmosphere, and the washing liquid is sent to recover uranium.
[0008] In a possible implementation, the fluorination reducing medium further includes any one of ammonium bifluoride, a mixed gas of hydrogen fluoride and ammonia, and a mixed gas of ammonium fluoride and hydrogen.
[0009] According to one aspect of an embodiment of the present disclosure, there is provided a method for preparing UF4, the method comprising:
[0010] Step 101, firstly add water and uranium dioxide into a liquid preparation tank, then slowly add industrial nitric acid of a preset concentration to dissolve and prepare a uranyl nitrate solution, filter and put it into a storage tank, and then prepare a uranyl nitrate liquid by liquid membrane evaporation and concentration;
[0011] Step 102, using a metering pump to quantitatively deliver the prepared uranyl nitrate liquid to a pneumatic atomizing nozzle, and spraying it into a dryer through a nitrogen atomizing nozzle that has been stabilized, metered, and preheated. The temperature of the uranyl nitrate liquid is maintained at a preset temperature, and the pipeline is insulated with hot water to prevent the uranyl nitrate from crystallizing. The dried uranyl nitrate falls into a silo;
[0012] Step 103, the uranyl nitrate crystals in the silo enter the reactor through the spiral and the temperature is controlled at a preset temperature. After reaching the required temperature, denitration begins, and hot nitrogen is introduced to remove NO2 from the tail gas;
[0013] Step 104, continue to replace the air in the reactor with nitrogen until the oxygen content of the gas in the reactor is less than 2%; the ammonium fluoride gas used for fluorination reduction is preheated to 550-750° C. and then introduced into the fluidized reactor to start fluidization;
[0014] Step 105, the uranium tetrafluoride produced by fluorination flows into the uranium tetrafluoride silo from the material outlet at the rear of the reactor, and is packaged and sent to the warehouse.
[0015] In a possible implementation, in step 101, the uranium concentration in the uranyl nitrate solution is 600-1500 gU / L, and the acidity of the solution is less than 1 mol / L.
[0016] In a possible implementation, in step 102, the prepared uranyl nitrate liquid is quantitatively delivered to a pneumatic atomizing nozzle by a metering pump, and sprayed into a dryer by a nitrogen atomizing nozzle that has been stabilized, metered, and preheated to 150-300° C. The temperature of the uranyl nitrate liquid is maintained at 80-150° C. The pipeline is insulated with hot water to prevent uranyl nitrate from crystallizing, and the dried uranyl nitrate falls into a silo.
[0017] In a possible implementation, in step 103, the reactor heating temperature is controlled at 350-450°C.
[0018] In a possible implementation, in step 104, the ammonium fluoride gas is preheated to 550-750° C. and then introduced into the fluidized reactor to start fluidization.
[0019] The beneficial effects of the present disclosure are as follows: the present disclosure provides a device and a process method for directly preparing uranium tetrafluoride from uranyl nitrate solution, and designs a uranium tetrafluoride preparation device that combines the characteristics of centrifugal spray drying and a horizontal fluorination reactor for the first time. Uranium tetrafluoride is directly prepared from uranyl nitrate solution in the same reactor through denitration, reduction, and fluorination. This can effectively solve the technical problems of large dry process material input, large wet nuclear critical safety pressure, and low efficiency in the current small amount of high-abundance UF4 preparation process, and provides a safe and efficient preparation device and operating process method for high-abundance materials of several hundred grams to several kilograms in scientific research and production. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 It is a schematic diagram of a device for preparing UF4 according to an exemplary embodiment.
[0021] Figure 2 It is a schematic diagram of a device for preparing UF4 according to an exemplary embodiment.
[0022] In the figure:
[0023] 1. Nozzle; 2. Dryer; 3. Separator; 4. Reactor; 5. Heating body; 6. Discharge port. DETAILED DESCRIPTION
[0024] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.
[0025] Figure 1 is a schematic diagram of a device for preparing UF4 according to an exemplary embodiment, such as Figure 1 As shown, the device includes a nozzle 1, a dryer 2, a separator 3, a reactor 4, a heating body 5 and a discharge port 6.
[0026] After the uranyl nitrate solution is extracted and stripped for purification, it is evaporated and concentrated by a membrane evaporator to obtain a uranyl nitrate liquid (the steam condensate produced by evaporating and concentrating the uranyl nitrate solution by the membrane evaporator can be used to recover uranium). The uranyl nitrate liquid is delivered to the nozzle 1 by a metering pump, is preheated at the nozzle 1, is atomized by nitrogen, and is then sprayed into the dryer 2. After being dried into uranyl nitrate crystals by the dryer 2, it is driven by a spiral feed port and delivered to the reactor 4.
[0027] The heating body 5 is wrapped around the outside of the reactor 4 and is used to heat the reactor 4 at a preset temperature. The ammonium fluoride gas is used as a fluorination reduction medium and enters the reactor 4 after being preheated to a specified temperature. The uranyl nitrate crystals are reduced to form uranium dioxide in the reactor 4 and fluorinated to form uranium tetrafluoride. The product uranium tetrafluoride is sent into the product packaging chamber through the discharge port 6 on the side wall of the reactor 4 by a spiral with a cooling jacket and loaded into the product container.
[0028] The principle of denitrification reaction is as follows.
[0029]
[0030] The principle of reduction reaction is as follows.
[0031]
[0032] 6UO2F2+4NH3→3UF4+3UO2+2N2
[0033] The principle of fluorination reaction is shown below.
[0034]
[0035] In a possible implementation, the separator 3 is connected to the dryer 2 and the reactor 4 respectively, and the nitrogen, excess hydrogen fluoride, ammonia, gas generated by the reaction and uranium fluoride powder entrained by water vapor escape, are filtered by the sintered stainless steel microporous filter in the diffusion cyclone separator 3, and then washed by the washing tower and discharged into the atmosphere, and the washing liquid is sent to recover uranium. In this way, measures can be taken to recover and recycle the excess ammonium fluoride in the tail gas.
[0036] In a possible implementation, the fluorination reducing medium may be any one of ammonium bifluoride, a mixed gas of hydrogen fluoride and ammonia, and a mixed gas of ammonium fluoride and hydrogen, in addition to ammonium fluoride.
[0037] Figure 2 is a flow chart of a method for preparing UF4 according to an exemplary embodiment. Figure 2 As shown, the method includes the following steps.
[0038] Step 101, first add water and uranium dioxide into a feed liquid preparation tank, then slowly add 98% industrial nitric acid to dissolve and prepare a uranyl nitrate solution, filter it with an 80-mesh stainless steel filter, put it into a storage tank, and then prepare a uranyl nitrate feed liquid by liquid membrane evaporation and concentration. The uranium concentration in the uranyl nitrate feed liquid is 600-1500gU / L, and the acidity of the feed liquid is less than 1mol / L.
[0039] Step 102, the prepared uranyl nitrate liquid is quantitatively fed into a pneumatic atomizing nozzle by a metering pump, and sprayed into a dryer by a high-purity nitrogen atomizing nozzle that has been stabilized, metered, and preheated to 150-300° C. The equipment and valves of the feeding system are insulated with steam, the temperature of the uranyl nitrate liquid is maintained at 80-150° C., and the pipeline is insulated with hot water to prevent the uranyl nitrate from crystallizing. The dried uranyl nitrate falls into the silo.
[0040] Step 103, the uranyl nitrate crystals enter the reactor through a spiral and the temperature is controlled at 350-450°C. After reaching the required temperature, denitration begins, and hot nitrogen is introduced to remove NO2 from the tail gas.
[0041] Step 104, continue to replace the air in the reactor with nitrogen until the oxygen content of the gas in the reactor is less than 2%. The ammonium fluoride gas used for fluorination reduction is preheated to 550-750°C and introduced into the fluidized reactor to start fluidization.
[0042] Step 105, the uranium tetrafluoride produced by fluorination flows into the uranium tetrafluoride silo from the material outlet at the rear of the reactor, and is packaged and sent to the warehouse.
[0043] As an example of this embodiment, in step 101, tap water and uranium trioxide are first added to the liquid preparation tank, and then 65% analytical pure nitric acid is slowly added to dissolve and prepare uranyl nitrate solution. After filtering with a flat filter, it is placed in a storage tank and then concentrated by liquid membrane evaporation to 1000gU / L, and the acidity of the liquid is 1mol / L.
[0044] In step 102, the feed liquid is quantitatively fed into the pneumatic atomizing nozzle by a metering pump, and is sprayed into the dryer by high-purity nitrogen gas that has been stabilized, metered, and preheated to 300°C. The equipment and valves of the feeding system are insulated with steam, the feed liquid temperature is maintained at 120°C, and the pipeline is insulated with hot water to prevent uranyl nitrate from crystallizing. The dried uranyl nitrate falls into the silo.
[0045] In step 103, the uranyl nitrate crystals enter the fluorination reactor through a spiral and the temperature is raised to 450°C. After reaching the required temperature, denitration begins, and hot nitrogen is introduced to remove NO2 from the tail gas.
[0046] In step 104, the air in the reactor is continuously replaced with nitrogen until the oxygen content of the gas in the reactor is less than 2%. The ammonium fluoride gas used for fluorination reduction is preheated to 650°C and introduced into the fluidized reactor to start fluidization.
[0047] In step 105, the uranium tetrafluoride produced by fluorination flows into the uranium tetrafluoride silo from the material outlet at the rear of the reactor and is packaged and sent to the warehouse.
[0048] As another example of this embodiment, in step 101, tap water and uranium trisilicon disulfide powder are first added to the feed liquid preparation tank, and then 65% analytical pure nitric acid is slowly added to dissolve and prepare uranyl nitrate solution. After filtering with a flat filter, the filter residue is collected and stored in a warehouse, and the filtrate is placed in a storage tank, and then concentrated by liquid membrane evaporation to 900gU / L, and the feed liquid acidity is 1mol / L.
[0049] In step 102, the feed liquid is quantitatively fed into the pneumatic atomizing nozzle by a metering pump, and is sprayed into the dryer by high-purity nitrogen gas that has been stabilized, metered, and preheated to 300°C. The equipment and valves of the feeding system are insulated with steam, the feed liquid temperature is maintained at 120°C, and the pipeline is insulated with hot water to prevent uranyl nitrate from crystallizing. The dried uranyl nitrate falls into the silo.
[0050] In step 103, the uranyl nitrate crystals enter the fluorination reactor through a spiral and the temperature is raised to 4000°C. After reaching the required temperature, denitration begins, and hot nitrogen is introduced to remove NO2 from the tail gas.
[0051] In step 104, the air in the reactor is continuously replaced with nitrogen until the oxygen content of the gas in the reactor is less than 2%. The ammonium fluoride gas used for fluorination reduction is preheated to 650°C and introduced into the fluidized reactor to start fluidization.
[0052] In step 105, the uranium tetrafluoride produced by fluorination flows into the uranium tetrafluoride silo from the material outlet at the rear of the reactor and is packaged and sent to the warehouse.
[0053] In one application example, the processing of depleted uranium products produces a large amount of intermediate materials such as smelting slag and turnings, which need to be recycled.
[0054] The smelting slag and turnings are placed in an oxidation furnace for high-temperature oxidation to convert into uranium trioxide. This type of uranium trioxide is placed in a dissolving tank and added with deionized water at a ratio of 1:1 to make a slurry. Stirring is started, and 65% nitric acid is slowly added to dissolve. After the dissolution is completed, it is filtered. The filtered liquid is placed in a storage tank and transported to a centrifugal extraction system through a metering pump. At the same time, TBP-sulfonated kerosene is introduced for extraction, and then dilute nitric acid is introduced for stripping. The stripping solution is placed in an evaporator for concentration, and the stripping solution is concentrated to 800g / l. An appropriate amount of nitrogen is introduced from the nozzle and the bottom of the reactor, and the water ring vacuum pump is started to pump the reactor into negative pressure. Uranium tetrafluoride base material is pre-added to the fluidized reactor and slowly added from the top of the reactor. After meeting the requirements, the water ring pump is stopped. Continue to replace the air in the reactor with nitrogen until the oxygen content of the gas in the reactor is less than 2%. The fluidized reactor begins to heat up to 450℃; ammonium fluoride is placed in the heater and begins to heat to 600℃, and the internal pressure is controlled at 0.25MPa. The concentrated uranium nitrate is quantitatively delivered to the pneumatic atomizing nozzle by a metering pump, and then sprayed into the fluidized reactor by high-purity nitrogen gas that has been stabilized, metered, and preheated to 130°C. The equipment and valves of the feeding system are insulated with steam, and the pipelines are insulated with hot water to prevent the crystallization of uranyl nitrate. At the same time, ammonium fluoride gas is introduced for fluidized fluorination reaction. The tail gas is filtered through a sintered nickel tube filter, and the ammonium fluoride is condensed through a condensing device, and a certain amount is accumulated to return to the process for use; other tail gases such as N2, NO2, etc. are discharged after being treated by the tail gas treatment system. After the fluorination reaction is completed, the uranium tetrafluoride is discharged from the discharge port and barreled for sampling.
[0055] The embodiments of the present disclosure have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.
Claims
1. A device for preparing UF4, characterized in that: The device comprises: a nozzle, a dryer, a separator, a reactor, a heating body and a discharge port; After the uranyl nitrate solution is extracted and stripped for purification, it is evaporated and concentrated by a membrane evaporator to obtain a uranyl nitrate liquid. The uranyl nitrate liquid is delivered to a nozzle by a metering pump, preheated at the nozzle, atomized by nitrogen, and then sprayed into a dryer. After being dried in the dryer to form uranyl nitrate crystals, it is driven by a spiral feed port and delivered to a reactor. The heating body is wrapped around the outside of the reactor and is used to heat the reactor at a preset temperature. Ammonium fluoride gas, as a fluorination reduction medium, enters the reactor after being preheated to a specified temperature. Uranyl nitrate crystals are reduced to form uranium dioxide in the reactor and are fluorinated to form uranium tetrafluoride. The product uranium tetrafluoride is delivered to the product packaging chamber through the discharge port on the side wall of the reactor by a spiral with a cooling jacket and loaded into the product container.
2. The device according to claim 1, characterized in that The separator is connected to the dryer and the reactor respectively. Nitrogen, excess hydrogen fluoride, ammonia, gases generated by the reaction and uranium fluoride powder entrained by water vapor escape, are filtered through the sintered stainless steel microporous filter in the diffusion cyclone separator, then washed in the washing tower and discharged into the atmosphere. The washing liquid is sent to recover uranium.
3. The device according to claim 1, characterized in that The fluoridation reducing medium also includes any one of ammonium bifluoride, a mixed gas of hydrogen fluoride and ammonia, and a mixed gas of ammonium fluoride and hydrogen.
4. A method for preparing UF4, characterized in that: The method comprises: Step 101, firstly add water and uranium dioxide into a liquid preparation tank, then slowly add industrial nitric acid of a preset concentration to dissolve and prepare a uranyl nitrate solution, filter and put it into a storage tank, and then prepare a uranyl nitrate liquid by liquid membrane evaporation and concentration; Step 102, using a metering pump to quantitatively deliver the prepared uranyl nitrate liquid to a pneumatic atomizing nozzle, and spraying it into a dryer through a nitrogen atomizing nozzle that has been stabilized, metered, and preheated. The temperature of the uranyl nitrate liquid is maintained at a preset temperature, and the pipeline is insulated with hot water to prevent the uranyl nitrate from crystallizing. The dried uranyl nitrate falls into a silo; Step 103, the uranyl nitrate crystals in the silo enter the reactor through the spiral and the temperature is controlled at a preset temperature. After reaching the required temperature, denitration begins, and hot nitrogen is introduced to remove NO2 from the tail gas; Step 104, continue to replace the air in the reactor with nitrogen until the oxygen content of the gas in the reactor is less than 2%; the ammonium fluoride gas used for fluorination reduction is preheated to 550-750° C. and then introduced into the fluidized reactor to start fluidization; Step 105, the uranium tetrafluoride produced by fluorination flows into the uranium tetrafluoride silo from the material outlet at the rear of the reactor, and is packaged and sent to the warehouse.
5. The method according to claim 4, characterized in that In step 101, the uranium concentration in the uranyl nitrate solution is 600-1500 gU / L, and the acidity of the solution is less than 1 mol / L.
6. The method according to claim 4, characterized in that In step 102, the prepared uranyl nitrate liquid is quantitatively delivered to a pneumatic atomizing nozzle by a metering pump, and sprayed into a dryer by a nitrogen atomizing nozzle that has been stabilized, metered, and preheated to 150-300° C. The temperature of the uranyl nitrate liquid is maintained at 80-150° C. The pipeline is insulated with hot water to prevent the uranyl nitrate from crystallizing, and the dried uranyl nitrate falls into a silo.
7. The method according to claim 4, characterized in that In step 103, the reactor heating temperature is controlled at 350-450°C.
8. The method according to claim 4, characterized in that In step 104, the ammonium fluoride gas is preheated to 550-750° C. and introduced into the fluidized reactor to start fluidization.