A method for end purification and centrifugal separation of crude uranium hexafluoride in a full dry method uranium purification conversion process

Abstract

This invention discloses a method for end-stage purification and centrifugal separation of crude uranium hexafluoride in a dry uranium purification and conversion process, relating to the field of natural uranium purification and conversion technology in the nuclear fuel cycle. The method includes the following steps: S1: Gasifying crude uranium hexafluoride to form a gaseous material; S2: Feeding the gaseous material into a centrifuge, causing light impurities to accumulate towards the center and uranium hexafluoride to accumulate towards the outer edge; S3: Collecting the light impurity-enriched phase and the purified uranium hexafluoride-enriched phase from the light phase outlet at the center and the heavy phase outlet at the outer edge, respectively. This invention achieves efficient separation of fluoride impurities from uranium hexafluoride at the end of the process, ensuring that the purified uranium hexafluoride meets the technical requirements for natural uranium hexafluoride, by feeding the gasified crude uranium hexafluoride into a centrifuge and utilizing the molecular weight difference between uranium hexafluoride and fluoride impurities in the centrifugal force field. The light impurities accumulate towards the center and the uranium hexafluoride accumulates towards the outer edge, and these are collected from the light phase outlet at the center and the heavy phase outlet at the outer edge, respectively.

Description

Technical Field

[0001] This invention relates to the field of natural uranium purification and conversion technology in the nuclear fuel cycle, specifically to a method for end-stage purification and centrifugal separation of crude uranium hexafluoride in a fully dry uranium purification and conversion process. Background Technology

[0002] Traditional uranium purification and conversion production lines have a long process. Before preparing uranium hexafluoride, uranium oxides undergo deep purification processes such as dissolution, extraction, back-extraction, calcination, hydrofluorination, and fluorination. Therefore, the final uranium hexafluoride produced has a low impurity content and its purity can meet the requirements of GB / T13375-2017 "Technical Conditions for Natural Uranium Hexafluoride".

[0003] With the development of the new generation of all-dry uranium purification and conversion technology, uranium hexafluoride is produced by directly denitrifying uranium oxide, hydrofluorinating, and fluorinating. This process greatly simplifies the process, reduces waste, and improves production efficiency. However, this process eliminates the multi-stage purification process of uranium oxide at the front end, resulting in excessive impurities in the uranium hexafluoride obtained directly after fluorination. According to the impurity standard of uranium octoxide in the national standard "Uranium Ore Concentrate" (GB / T10268-2008), the impurities in the crude uranium hexafluoride product are mainly fluoride impurities of vanadium and molybdenum, and the overall impurity content is low (around 1.5%), which cannot meet the ppm level requirements of "Technical Conditions for Natural Uranium Hexafluoride" (GB / T13375-2017).

[0004] Traditional separation methods, such as cryogenic distillation and chemisorption, suffer from problems such as long processes and severe equipment corrosion, and are ineffective at removing low-content impurities, making deep impurity removal difficult. Gas centrifugation has a narrow application in traditional chemical industries, and its technology is mainly used for regulating uranium isotope abundance in the nuclear industry. Currently, there is no complete gas-phase centrifugation purification process for the synergistic removal of multiple fluoride impurities from crude uranium hexafluoride in the next-generation all-dry uranium purification and conversion process.

[0005] Therefore, this invention provides a gas-phase centrifugal separation method that achieves efficient fractionation of Mo and V in uranium hexafluoride at the end, solving the problem of excessive impurities in the all-dry process. Summary of the Invention

[0006] This invention provides a method for the end-stage purification and centrifugal separation of crude uranium hexafluoride in a fully dry uranium purification and conversion process. The method involves vaporizing crude uranium hexafluoride and feeding it into a centrifuge. In the centrifugal force field, the molecular weight difference between uranium hexafluoride and fluoride impurities causes lighter impurities to accumulate towards the center and uranium hexafluoride to accumulate towards the outer edge. The impurities are then collected from the light phase outlet at the center and the heavy phase outlet at the outer edge, respectively. This method solves the technical problem in the fully dry uranium purification and conversion process where the elimination of multiple purification stages at the front end leads to excessive fluoride impurities in crude uranium hexafluoride, failing to meet the technical requirements for natural uranium hexafluoride.

[0007] To address the aforementioned technical problems, embodiments of the present invention provide a method for the end-stage purification and centrifugal separation of crude uranium hexafluoride in a fully dry uranium purification and conversion process, comprising the following steps: S1: Crude uranium hexafluoride is vaporized to form a stable gaseous material; S2: The gaseous material is fed into a centrifuge. Under the action of centrifugal force, the molecular weight difference between uranium hexafluoride and fluoride impurities is used to enrich the light impurities towards the axis and the uranium hexafluoride towards the outer edge. S3: Extract the light impurity enriched phase and the purified uranium hexafluoride enriched phase from the light phase outlet at the axial center and the heavy phase outlet at the outer edge, respectively.

[0008] As an optional implementation, the impurities in the crude uranium hexafluoride include molybdenum fluoride and / or vanadium fluoride. Preferably, the molybdenum content is ≤0.4% (MoF6 ≤0.88%), the vanadium content is ≤0.4% (VF5 ≤1.15%), and the total impurity content is 1-2%.

[0009] As an optional implementation, the gasification in S1 includes heating crude uranium hexafluoride to 50-80°C and controlling the pressure to 0.1-0.3 MPa, so that uranium hexafluoride and its fluoride impurities are in a stable gas phase.

[0010] Specifically, the core purpose of this temperature and pressure is to ensure that uranium hexafluoride and its impurities remain in a stable gaseous phase throughout the process, avoiding liquid / solid phase deposition. At 0.1 MPa and 50°C, uranium hexafluoride sublimation is guaranteed; lower temperatures lead to unstable solid-phase sublimation. Temperatures below 80°C prevent corrosion of the equipment, while excessively high temperatures can cause trace decomposition of uranium hexafluoride. Pressures between 0.1 and 0.3 MPa are crucial; too low a pressure leads to gaseous instability and the potential for liquid / solid production, while too high a pressure increases equipment costs. This embodiment of the invention ensures that uranium hexafluoride and its fluoride impurities remain in a stable and homogeneous gaseous phase, preventing liquid phase formation and solid deposition.

[0011] As an optional implementation, before feeding the gaseous material into the centrifuge in S2, a pressure-stabilizing injection step is also included. The pressure-stabilizing injection step includes buffering and stabilizing the vaporized gaseous material to control the injection pressure to be lower than the vaporization pressure, and controlling the feed flow rate through a mass flow meter.

[0012] As an optional implementation, in the pressure stabilization injection step, the pressure after buffer stabilization is controlled between 0.08 MPa and 0.25 MPa.

[0013] Specifically, at this pressure, the buffer pressure can be kept slightly lower than the vaporization pressure to facilitate stable gas flow. Too low a pressure leads to gas phase instability, making the material prone to sublimation or condensation; too high a pressure causes interference with the rotor flow field when entering the centrifuge, affecting subsequent internal stability. In this embodiment of the invention, the feed flow rate is controlled by a mass flow meter (the specific feed rate directly depends on the selected centrifuge rotor size and designed throughput) to maintain a uniform and stable flow field within the centrifuge rotor.

[0014] As an optional implementation, the centrifuge chamber jacket temperature control in S2 is 50-80°C, the internal operating pressure is 0.05-0.2MPa, the centrifuge speed is 6000-15000r / min, and the entire process is maintained in a gas phase state.

[0015] Specifically, in this embodiment of the invention, the temperature and pressure settings are optimal control parameters to ensure that the entire gas phase is maintained, while the pressure is slightly lower than the injection pressure to maintain the gas flow direction. This is because parameters that are too low will lead to unstable gas phase conditions, while parameters that are too high will increase the requirements on the equipment without significantly improving separation efficiency.

[0016] In this embodiment of the invention, a pressurized gas phase is maintained throughout the process. Under the action of a centrifugal force field, the centrifuge speed is controlled between 6000 and 15000 r / min. The principle is as follows: In a centrifugal force field, components of different molecular weights are distributed radially. According to the radial distribution law, components with smaller molecular weights tend to accumulate towards the center (low-pressure zone), while components with larger molecular weights tend to accumulate towards the outer wall. If the centrifugal speed is too low, the centrifugal force field is insufficient, the separation factor is too small, and molecular diffusion cannot be effectively overcome, resulting in low removal efficiency of light components. High centrifugal speeds lead to a sharp increase in energy consumption, causing mechanical stability problems such as excessive stress and intensified vibration.

[0017] In this embodiment of the invention, fluoride impurities of Mo and V with smaller molecular weights are enriched towards the axis, while UF6 with larger molecular weights is enriched towards the outer edge.

[0018] As an optional implementation, S3 includes installing regulating valves and flow meters on the light phase outlet and heavy phase outlet pipelines respectively, and controlling the split ratio of light phase volume flow rate to total feed volume flow rate to be 0.2 to 0.6 by adjusting the opening of the two outlet valves.

[0019] As an optional implementation, S2 includes controlling the average residence time of the gaseous material in the centrifuge to be 1 to 3 minutes by adjusting the feed volume flow rate.

[0020] Preferably, in this embodiment of the invention, the centrifuge adopts a dual-path independent extraction structure with a central light phase outlet and an outer heavy phase outlet. The central outlet is used to extract the light impurity enriched phase, and the outer outlet is used to extract the purified uranium hexafluoride enriched phase.

[0021] The material outlet control method is as follows: regulating valves and flow meters are installed on the light phase outlet and heavy phase outlet pipelines respectively; by adjusting the opening of the two outlet valves, the output flow ratio of the light phase and heavy phase is controlled, and the flow ratio is adjusted in real time according to the split ratio θ = light phase volume flow rate / total feed volume flow rate, so that the flow ratio is stabilized in the range of 0.2 to 0.6.

[0022] The volumetric flow rate of crude uranium hexafluoride gaseous feed is precisely controlled by a mass flow meter. Combined with the effective separation chamber volume, temperature and operating pressure of the centrifuge, the average residence time of the gaseous material in the centrifugal force field is calculated and controlled. The residence time is shortened by increasing the feed flow rate and extended by decreasing the feed flow rate. The average residence time is stably controlled between 1 and 3 minutes to ensure that the material achieves sufficient radial separation in the centrifuge, while avoiding excessive residence time that would lead to a decrease in production efficiency.

[0023] As an optional implementation, the purified uranium hexafluoride enriched phase in S3 is collected after being cooled and solidified by a condenser, and the light impurity enriched phase is discharged harmlessly after being condensed, recovered, and rinsed with alkaline solution.

[0024] Preferably, the purified uranium hexafluoride gas phase enters the condenser, cools down to 10-30°C, sublimates and solidifies, and is stored in the product storage tank. The light phase tail gas is condensed and recovered, and then subjected to multi-stage alkaline scrubbing to achieve harmless discharge.

[0025] As an alternative implementation method, multi-stage centrifuge cascade separation is employed to meet different purity requirements.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) In this embodiment of the invention, crude uranium hexafluoride is gasified to form a stable gaseous material and then fed into a centrifuge. Under the action of centrifugal force, the molecular weight difference between uranium hexafluoride and fluoride impurities is utilized to enrich light impurities towards the axis and uranium hexafluoride towards the outer edge. The light impurity enriched phase and the purified uranium hexafluoride enriched phase are respectively collected from the light phase outlet at the axis and the heavy phase outlet at the outer edge. Thus, without changing the main process flow of the all-dry uranium purification and conversion, the efficient separation of fluoride impurities and uranium hexafluoride in crude uranium hexafluoride is achieved at the end, so that the purified uranium hexafluoride meets the technical requirements for impurity content of natural uranium hexafluoride.

[0027] (2) In this embodiment of the invention, the vaporized gaseous material is buffered and stabilized to make the injection pressure lower than the vaporization pressure, and the feed flow rate is precisely controlled by a mass flow meter before being sent into a centrifuge. In the gas phase centrifuge field with a chamber jacket temperature of 50-80℃, an internal operating pressure of 0.05-0.2MPa, and a rotation speed of 6000-15000r / min, the molecular weight difference between uranium hexafluoride and fluoride impurities is used to enrich the light impurities towards the axis and the uranium hexafluoride towards the outer edge. At the same time, regulating valves and flow meters are respectively installed on the light phase outlet and the heavy phase outlet pipeline. By adjusting the opening of the two outlet valves, the split ratio of the light phase volume flow rate to the total feed volume flow rate is controlled within the range of 0.2-0.6. In conjunction with the adjustment of the feed volume flow rate, the average residence time of the gaseous material in the centrifuge is stabilized at 1-3min. After the material undergoes sufficient radial separation in a centrifugal force field, the light impurity-enriched phase and the purified uranium hexafluoride-enriched phase are collected from the light phase outlet at the center and the heavy phase outlet at the outer edge, respectively. This allows for the maintenance of a uniform and stable flow field within the centrifuge rotor through pressure-stabilized injection. The coordinated control of temperature, pressure, and rotational speed ensures a gaseous state throughout the process and enhances the separation factor. Precise matching of the split ratio and residence time achieves an optimized balance between impurity removal efficiency and production efficiency. Deep purification of crude uranium hexafluoride is completed under full gas phase conditions, avoiding equipment corrosion and flow field disturbance problems caused by liquid phase deposition. The purified uranium hexafluoride meets the impurity content requirements of natural uranium hexafluoride technology, and the process is stable with low equipment corrosion risk. It can be flexibly expanded to construct multi-stage cascade separation systems to adapt to different production scenarios based on product purity requirements.

[0028] (3) The crude uranium hexafluoride is heated to 50-80℃ and pressurized to 0.1-0.3MPa for vaporization, so that uranium hexafluoride and its fluoride impurities are in a stable and homogeneous gas phase. The vaporized gas phase material is then buffered and pressure-stabilized to control the injection pressure to 0.08-0.25MPa. The feed flow rate is controlled by a mass flow meter and then sent to a centrifuge. In a centrifugal force field with a temperature of 50-80℃ in the chamber jacket, an internal operating pressure of 0.05-0.2MPa, and a rotation speed of 6000-15000r / min, the molecular weight difference between uranium hexafluoride and molybdenum fluoride and / or vanadium fluoride is utilized to enrich the smaller molecular weight molybdenum and vanadium fluoride impurities towards the axis and the larger molecular weight uranium hexafluoride towards the outer edge. The light impurity enriched phase and the purified uranium hexafluoride enriched phase are collected from the light phase outlet at the axis and the heavy phase outlet at the outer edge, respectively. The purified uranium hexafluoride enriched phase is cooled to 10-30℃ in a condenser, solidified, and then stored in a product storage tank. The light impurity enriched phase is condensed and recovered, and then discharged harmlessly after multi-stage alkaline rinsing. Thus, the material is kept in a stable gas phase throughout the process by precise control of vaporization temperature and pressure, avoiding the formation of liquid phase and solid deposition. The gas flow direction is kept stable by reasonable setting of the injection pressure, and interference with the rotor flow field is prevented. In view of the characteristics of high molybdenum and vanadium fluoride impurities in crude uranium hexafluoride in the all-dry process, with an overall impurity content of about 1.5%, the process achieves one-time synergistic removal of multi-component impurities, and completes the deep removal of low-content impurities that are difficult to achieve by conventional distillation and ordinary separation methods. The purified uranium hexafluoride meets the ppm level index requirements. At the same time, the all-gas phase operation significantly reduces the risk of equipment corrosion, and the tail gas is discharged harmlessly after multi-stage treatment.

[0029] (4) In this embodiment of the invention, crude uranium hexafluoride is vaporized to form a stable gaseous material and then fed into a centrifuge. In the centrifugal force field, the molecular weight difference between uranium hexafluoride and fluoride impurities is used to enrich the light impurities towards the axis and the uranium hexafluoride towards the outer edge. By adjusting the feed volume flow rate, the average residence time of the gaseous material in the centrifuge is controlled to be 1-3 min. A multi-stage centrifuge cascade separation method is adopted so that the material can obtain sufficient radial separation in the centrifugal force field and then the light impurity enriched phase and the purified uranium hexafluoride enriched phase are collected from the light phase outlet at the axis and the heavy phase outlet at the outer edge, respectively. Thus, by optimizing the residence time control, the material can obtain sufficient radial separation in the centrifuge while avoiding the production efficiency decrease due to excessive residence time. The flexible construction of the multi-stage cascade separation system can meet the purity index requirements of different products. It can not only meet the needs of small-scale test verification but also realize industrial scale-up production. The purified uranium hexafluoride meets the index requirements of impurity content of natural uranium hexafluoride technology. Moreover, the technical route is feasible, flexible in expansion, and has excellent engineering extensibility. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0031] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known materials or methods have not been specifically described in order to avoid obscuring the invention.

[0032] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described herein, as well as the features of those different embodiments or examples.

[0033] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0034] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0035] This invention addresses the challenges of a new generation of all-dry uranium purification and conversion processes, characterized by a lack of front-end purification and high levels of uranium hexafluoride (UF6) impurities. It provides a method for the final purification and centrifugal separation of crude UF6 during this process (UF6 molar mass is 352, significantly greater than MoF6 (210) and VF5 (146). Under centrifugal force, the molecular weight difference creates a distinct radial distribution, with lighter impurities accumulating towards the axis and UF6 accumulating towards the outer wall). Through pressurized gasification, stable-pressure feeding, centrifugal separation, two-phase staged extraction, condensation recovery, and tail gas treatment, efficient purification of UF6 is achieved. Specifically, this includes the following: (1) Pressurized gasification The prepared crude uranium hexafluoride is heated to 50–80°C and the pressure is controlled at 0.1–0.3 MPa to ensure that uranium hexafluoride and its fluoride impurities are in a stable and homogeneous gas phase, thus avoiding the formation of liquid phase and solid deposition.

[0036] The main impurities in the crude uranium hexafluoride are molybdenum fluoride and / or vanadium fluoride, with a total impurity content of approximately 1-2%.

[0037] (2) Pressure-stabilized feeding The vaporized gaseous material is buffered and stabilized, and the injection pressure is controlled at 0.08-0.25 MPa. The injection pressure is kept slightly lower than the vaporization pressure. The feed flow rate is controlled by a mass flow meter to make the flow field inside the centrifuge rotor uniform and stable.

[0038] (3) Centrifugal separation The pressurized gaseous material is fed into a centrifuge. The temperature of the centrifuge chamber jacket is controlled at 50-80℃, the internal operating pressure is 0.05-0.2MPa, and the centrifuge speed is controlled at 6000-15000r / min, maintaining the gaseous state throughout the process. Under the influence of centrifugal force, taking advantage of the molecular weight difference between uranium hexafluoride and fluoride impurities, the fluoride impurities with smaller molecular weights are enriched towards the axis, while the uranium hexafluoride impurities with larger molecular weights are enriched towards the outer edge.

[0039] (4) Two-phase classification The centrifuge adopts a dual-path independent extraction structure with a light phase outlet at the center and a heavy phase outlet at the outer edge; A regulating valve and a flow meter are installed on the light phase outlet and heavy phase outlet pipelines respectively. By adjusting the opening of the two outlet valves, the split ratio of the light phase volume flow rate to the total feed volume flow rate is controlled to be 0.2 to 0.6. The feed volume flow rate is precisely controlled by a mass flow meter to keep the average residence time of gaseous materials in the centrifuge within 1 to 3 minutes. After the material undergoes sufficient radial separation in the centrifugal force field, the light impurity enriched phase is discharged from the light phase outlet at the center, and the purified uranium hexafluoride enriched phase is discharged from the heavy phase outlet at the outer edge.

[0040] (5) Condensation collection The purified uranium hexafluoride-enriched phase is fed into a condenser, cooled to 10–30°C, sublimated and solidified, and then stored in a product storage tank.

[0041] (6) Exhaust gas treatment The light impurity-enriched phase is recovered by condensation and then washed with alkaline solution in multiple stages to achieve harmless discharge.

[0042] It should be noted that, in the embodiments of the present invention, a multi-stage cascade separation system can be constructed by using multi-stage centrifuges in series to meet the needs of different production scenarios, based on the product purity index requirements.

[0043] This invention specifically addresses the problem of increased uranium hexafluoride impurities due to the lack of a purification process at the front end of uranium purification and conversion. It achieves end-stage purification of uranium hexafluoride without altering the main process flow. Furthermore, depending on the content of impurity elements in the uranium oxide feedstock, it can achieve synergistic removal of vanadium and molybdenum fluorides in a single step, demonstrating greater adaptability to mixed fluoride impurities that are difficult to handle using traditional methods.

[0044] The gas centrifugation method of this invention relies on the ultra-high speed centrifugal field to finely sieve components of different molecular weights. Even when the background impurity content of the raw material is low, it can still achieve high-precision fractional separation of impurities and main components by means of molecular weight difference. It can achieve deep removal of low-content impurities that is difficult to achieve by conventional distillation and ordinary separation methods. It has irreplaceable fine separation advantages in the high-purity preparation of low-impurity materials.

[0045] The embodiments of this invention fully verified the feasibility of the impurity removal process through centrifugal separation experiments; the entire process operates in the gas phase, with no liquid phase deposition, resulting in low equipment corrosion risk and stable operation. In engineering applications, multi-stage cascade separation systems can be flexibly constructed according to product purity requirements, meeting both small-scale experimental verification needs and adapting to industrial-scale production scenarios, demonstrating excellent adaptability and engineering scalability.

[0046] To better demonstrate the significant effects of the embodiments of the present invention, specific experimental examples will be conducted below for verification.

[0047] Example 1: This embodiment of the invention provides a method for the end-stage purification and centrifugal separation of crude uranium hexafluoride in a completely dry uranium purification and conversion process, including the following: (1) Pressurized gasification The prepared crude uranium hexafluoride was heated to 60°C and the pressure was controlled at 0.15 MPa to ensure that the uranium hexafluoride and its fluoride impurities were in a stable and homogeneous gas phase, thus avoiding the formation of liquid phase and solid deposition.

[0048] The crude uranium hexafluoride contains 0.48 wt% MoF6, 1.03 wt% VF5, and 98.41 wt% UF6, with the remaining 0.08 wt% being the total amount of trace impurities that meet the standards.

[0049] (2) Pressure-stabilized feeding The vaporized gaseous material is buffered and stabilized, and the injection pressure is controlled at 0.12 MPa. The injection pressure is kept slightly lower than the vaporization pressure. The feed flow rate is controlled by a mass flow meter to make the flow field inside the centrifuge rotor uniform and stable.

[0050] (3) Centrifugal separation The pressurized gaseous material is fed into a centrifuge. The temperature of the centrifuge chamber jacket is controlled at 60°C, the internal operating pressure is 0.1MPa, and the centrifuge speed is controlled at 8000r / min. The gaseous state is maintained throughout the process. Under the influence of centrifugal force, taking advantage of the molecular weight difference between uranium hexafluoride and fluoride impurities, the fluoride impurities with smaller molecular weights are enriched towards the axis, while the uranium hexafluoride impurities with larger molecular weights are enriched towards the outer edge.

[0051] (4) Two-phase classification The centrifuge adopts a dual-path independent extraction structure with a light phase outlet at the center and a heavy phase outlet at the outer edge; A regulating valve and a flow meter are installed on the light phase outlet and heavy phase outlet pipelines respectively. By adjusting the opening of the two outlet valves, the flow ratio of the light phase volume flow rate to the total feed volume flow rate is controlled to be 0.4. The feed volume flow rate is precisely controlled by a mass flow meter to keep the average residence time of gaseous materials in the centrifuge within 2 minutes. After the material undergoes sufficient radial separation in the centrifugal force field, the light impurity enriched phase is discharged from the light phase outlet at the center, and the purified uranium hexafluoride enriched phase is discharged from the heavy phase outlet at the outer edge.

[0052] (5) Condensation collection The purified uranium hexafluoride-enriched phase is introduced into a condenser, cooled to 20°C, sublimated and solidified, and then stored in a product storage tank.

[0053] (6) Exhaust gas treatment The light impurity-enriched phase is recovered by condensation and then washed with alkaline solution in multiple stages to achieve harmless discharge.

[0054] The test results are shown in Table 1 below. Determination of molybdenum (Mo) in uranium hexafluoride: GB / T13700-1992 Spectrophotometric method; Determination of vanadium (V) in uranium hexafluoride: GB / T13699-1992 Spectrophotometric method; Determination of uranium (U) in uranium hexafluoride: GB / T14501.6-2008 "Analytical methods for uranium hexafluoride - Part 6: Determination of uranium".

[0055]

[0056] Example 2: This embodiment of the invention provides a method for the end-stage purification and centrifugal separation of crude uranium hexafluoride in a completely dry uranium purification and conversion process, including the following: (1) Pressurized gasification The prepared crude uranium hexafluoride was heated to 65°C and the pressure was controlled at 0.12 MPa to ensure that the uranium hexafluoride and its fluoride impurities were in a stable and homogeneous gas phase, thus avoiding the formation of liquid phase and solid deposition.

[0057] The crude uranium hexafluoride contains 0.5 wt% MoF6, 0.97 wt% VF5, and 98.45 wt% UF6, with the remaining 0.08 wt% being the total amount of trace impurities that meet the standards.

[0058] (2) Pressure-stabilized feeding The vaporized gaseous material is buffered and stabilized, and the injection pressure is controlled at 0.1 MPa. The injection pressure is kept slightly lower than the vaporization pressure. The feed flow rate is controlled by a mass flow meter to make the flow field inside the centrifuge rotor uniform and stable.

[0059] (3) Centrifugal separation The pressurized gaseous material is fed into a centrifuge. The temperature of the centrifuge chamber jacket is controlled at 55℃, the internal operating pressure is 0.08MPa, and the centrifuge speed is controlled at 10000r / min. The gaseous state is maintained throughout the process. Under the influence of centrifugal force, taking advantage of the molecular weight difference between uranium hexafluoride and fluoride impurities, the fluoride impurities with smaller molecular weights are enriched towards the axis, while the uranium hexafluoride impurities with larger molecular weights are enriched towards the outer edge.

[0060] (4) Two-phase classification The centrifuge adopts a dual-path independent extraction structure with a light phase outlet at the center and a heavy phase outlet at the outer edge; A regulating valve and a flow meter are installed on the light phase outlet and heavy phase outlet pipelines respectively. By adjusting the opening of the two outlet valves, the flow ratio of the light phase volume flow rate to the total feed volume flow rate is controlled to be 0.5. The feed volume flow rate is precisely controlled by a mass flow meter to keep the average residence time of gaseous materials in the centrifuge within 3 minutes. After the material undergoes sufficient radial separation in the centrifugal force field, the light impurity enriched phase is discharged from the light phase outlet at the center, and the purified uranium hexafluoride enriched phase is discharged from the heavy phase outlet at the outer edge.

[0061] (5) Condensation collection The purified uranium hexafluoride-enriched phase is introduced into a condenser, cooled to 20°C, sublimated and solidified, and then stored in a product storage tank.

[0062] (6) Exhaust gas treatment The light impurity-enriched phase is recovered by condensation and then washed with alkaline solution in multiple stages to achieve harmless discharge.

[0063] The test results are shown in Table 2 below:

[0064] Example 3: This embodiment of the invention provides a method for the end-stage purification and centrifugal separation of crude uranium hexafluoride in a completely dry uranium purification and conversion process, including the following: (1) Pressurized gasification The prepared crude uranium hexafluoride was heated to 50°C and the pressure was controlled at 0.1 MPa to ensure that the uranium hexafluoride and its fluoride impurities were in a stable and homogeneous gas phase, thus avoiding the formation of liquid phase and solid deposition.

[0065] The crude uranium hexafluoride contains 0.48 wt% MoF6, 1.03 wt% VF5, and 98.41 wt% UF6, with the remaining 0.08 wt% being the total amount of trace impurities that meet the standards.

[0066] (2) Pressure-stabilized feeding The vaporized gaseous material is buffered and stabilized, and the injection pressure is controlled at 0.08 MPa. The injection pressure is kept slightly lower than the vaporization pressure. The feed flow rate is controlled by a mass flow meter to make the flow field inside the centrifuge rotor uniform and stable.

[0067] (3) Centrifugal separation The pressurized gaseous material is fed into a centrifuge. The temperature of the centrifuge chamber jacket is controlled at 50°C, the internal operating pressure is 0.05MPa, and the centrifuge speed is controlled at 6000r / min. The gaseous state is maintained throughout the process. Under the influence of centrifugal force, taking advantage of the molecular weight difference between uranium hexafluoride and fluoride impurities, the fluoride impurities with smaller molecular weights are enriched towards the axis, while the uranium hexafluoride impurities with larger molecular weights are enriched towards the outer edge.

[0068] (4) Two-phase classification The centrifuge adopts a dual-path independent extraction structure with a light phase outlet at the center and a heavy phase outlet at the outer edge; A regulating valve and a flow meter are installed on the light phase outlet and heavy phase outlet pipelines respectively. By adjusting the opening of the two outlet valves, the flow ratio of the light phase volume flow rate to the total feed volume flow rate is controlled to be 0.2. The feed volume flow rate is precisely controlled by a mass flow meter to keep the average residence time of gaseous materials in the centrifuge within 1 minute. After the material undergoes sufficient radial separation in the centrifugal force field, the light impurity enriched phase is discharged from the light phase outlet at the center, and the purified uranium hexafluoride enriched phase is discharged from the heavy phase outlet at the outer edge.

[0069] The test results are shown in Table 3 below:

[0070] Example 4: This embodiment of the invention provides a method for the end-stage purification and centrifugal separation of crude uranium hexafluoride in a completely dry uranium purification and conversion process, including the following: (1) Pressurized gasification The prepared crude uranium hexafluoride was heated to 80°C and the pressure was controlled at 0.3 MPa to ensure that the uranium hexafluoride and its fluoride impurities were in a stable and homogeneous gas phase, thus avoiding the formation of liquid phase and solid deposition.

[0071] The crude uranium hexafluoride contains 0.48 wt% MoF6, 1.03 wt% VF5, and 98.41 wt% UF6, with the remaining 0.08 wt% being the total amount of trace impurities that meet the standards.

[0072] (2) Pressure-stabilized feeding The vaporized gaseous material is buffered and stabilized, and the injection pressure is controlled at 0.25 MPa. The injection pressure is kept slightly lower than the vaporization pressure. The feed flow rate is controlled by a mass flow meter to make the flow field inside the centrifuge rotor uniform and stable.

[0073] (3) Centrifugal separation The pressurized gaseous material is fed into a centrifuge. The temperature of the centrifuge chamber jacket is controlled at 80℃, the internal operating pressure is 0.2MPa, and the centrifuge speed is controlled at 15000r / min. The gaseous state is maintained throughout the process. Under the influence of centrifugal force, taking advantage of the molecular weight difference between uranium hexafluoride and fluoride impurities, the fluoride impurities with smaller molecular weights are enriched towards the axis, while the uranium hexafluoride impurities with larger molecular weights are enriched towards the outer edge.

[0074] (4) Two-phase classification The centrifuge adopts a dual-path independent extraction structure with a light phase outlet at the center and a heavy phase outlet at the outer edge; A regulating valve and a flow meter are installed on the light phase outlet and heavy phase outlet pipelines respectively. By adjusting the opening of the two outlet valves, the flow ratio of the light phase volume flow rate to the total feed volume flow rate is controlled to be 0.6. The feed volume flow rate is precisely controlled by a mass flow meter to keep the average residence time of gaseous materials in the centrifuge within 3 minutes. After the material undergoes sufficient radial separation in the centrifugal force field, the light impurity enriched phase is discharged from the light phase outlet at the center, and the purified uranium hexafluoride enriched phase is discharged from the heavy phase outlet at the outer edge.

[0075] The test results are shown in Table 4 below:

[0076] Example 5: This embodiment of the invention provides a method for end-stage purification and centrifugal separation of crude uranium hexafluoride in a fully dry uranium purification and conversion process. The crude uranium hexafluoride contains 0.48 wt% MoF6, 1.03 wt% VF5, and 98.41 wt% UF6, with the remaining 0.08 wt% being the total amount of trace impurities that meet the standards. This includes the following: (1) Pressurized gasification The prepared crude uranium hexafluoride was heated to 60°C and the pressure was controlled at 0.12 MPa to ensure that the uranium hexafluoride and its fluoride impurities were in a stable and homogeneous gas phase, thus avoiding the formation of liquid phase and solid deposition.

[0077] (2) Pressure-stabilized feeding The vaporized gaseous material is buffered and stabilized, and the injection pressure is controlled at 0.12 MPa. The injection pressure is kept slightly lower than the vaporization pressure. The feed flow rate is controlled by a mass flow meter to make the flow field inside the centrifuge rotor uniform and stable.

[0078] (3) Centrifugal separation The pressurized gaseous material is fed into a centrifuge. The temperature of the centrifuge chamber jacket is controlled at 60°C, the internal operating pressure is 0.1MPa, and the centrifuge speed is controlled at 8000r / min. The gaseous state is maintained throughout the process. Under the influence of centrifugal force, taking advantage of the molecular weight difference between uranium hexafluoride and fluoride impurities, the fluoride impurities with smaller molecular weights are enriched towards the axis, while the uranium hexafluoride impurities with larger molecular weights are enriched towards the outer edge.

[0079] (4) Two-phase classification The centrifuge adopts a dual-path independent extraction structure with a light phase outlet at the center and a heavy phase outlet at the outer edge; A regulating valve and a flow meter are installed on the light phase outlet and heavy phase outlet pipelines respectively. By adjusting the opening of the two outlet valves, the flow ratio of the light phase volume flow rate to the total feed volume flow rate is controlled to be 0.4. The feed volume flow rate is precisely controlled by a mass flow meter to keep the average residence time of gaseous materials in the centrifuge within 2 minutes. After the material undergoes sufficient radial separation in the centrifugal force field, the light impurity enriched phase is discharged from the light phase outlet at the center, and the purified uranium hexafluoride enriched phase is discharged from the heavy phase outlet at the outer edge.

[0080] (5) Condensation collection The purified uranium hexafluoride-enriched phase is introduced into a condenser, cooled to 20°C, sublimated and solidified, and then stored in a product storage tank.

[0081] (6) Repeat centrifugation twice. After a single centrifugation, the heavy components at the heavy phase outlet are collected and used as feed material. The experiment is repeated twice according to steps (1)-(5), and the heavy phase outlet is analyzed each time.

[0082] (7) Exhaust gas treatment The light impurity-enriched phase is recovered by condensation and then washed with alkaline solution in multiple stages to achieve harmless discharge.

[0083] The test results are shown in Table 5 below:

[0084] As can be seen from Tables 1 and 2, when molybdenum ≤ 0.4% (MoF6 ≤ 0.88%), vanadium ≤ 0.4% (VF5 ≤ 1.15%), and the total impurity content is 1-2%, the purification and centrifugation methods of the embodiments of the present invention can achieve good purification and separation effects.

[0085] As shown in Tables 1, 3, and 4, after heating and vaporizing crude uranium hexafluoride to form a stable gaseous material, it is fed into a centrifuge. In the centrifugal force field, the molecular weight difference between uranium hexafluoride and fluoride impurities is utilized to enrich the lighter impurities towards the axis and the uranium hexafluoride towards the outer edge. The light impurity-enriched phase and the purified uranium hexafluoride-enriched phase are respectively collected from the light phase outlet at the axis and the heavy phase outlet at the outer edge. Thus, without changing the main process flow of the all-dry uranium purification and conversion, the efficient separation of fluoride impurities and uranium hexafluoride from crude uranium hexafluoride is achieved at the end.

[0086] As shown in Table 5, increasing the number of centrifugation cycles can continuously reduce impurities in crude uranium hexafluoride, ultimately ensuring that the purified uranium hexafluoride meets the impurity content requirements of the natural uranium hexafluoride technical specifications. The process conditions in Example 1 demonstrate superior uranium hexafluoride purification, achieving the optimal balance between energy consumption and separation efficiency. This verifies that process parameters must be controlled within a reasonable range to achieve synergistic optimization of separation efficiency, production energy consumption, and equipment stability; otherwise, insufficient separation or reduced economic efficiency may result.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for the end purification of crude hexafluorouranium in a full dry process uranium purification conversion process, centrifugation, characterized in that, Includes the following steps: S1: Crude uranium hexafluoride is vaporized to form a gaseous material; S2: The gaseous material is fed into a centrifuge. Under the action of centrifugal force, the molecular weight difference between uranium hexafluoride and fluoride impurities is used to enrich the light impurities towards the axis and the uranium hexafluoride towards the outer edge. S3: Extract the light impurity enriched phase and the purified uranium hexafluoride enriched phase from the light phase outlet at the axial center and the heavy phase outlet at the outer edge, respectively.

2. A method for the end purification and centrifugal separation of crude hexafluorouranium in a full dry process uranium purification conversion process according to claim 1, characterized in that, Impurities in the crude uranium hexafluoride include molybdenum fluoride and / or vanadium fluoride.

3. A method for the end purification and centrifugal separation of crude hexafluorouranium in a full dry process uranium purification conversion process according to claim 2, characterized in that, The gasification described in S1 involves heating crude uranium hexafluoride to 50–80°C and controlling the pressure to 0.1–0.3 MPa, so that uranium hexafluoride and its fluoride impurities are in a stable gas phase.

4. A method for end-stage purification and centrifugal separation of crude uranium hexafluoride in a dry uranium purification and conversion process according to any one of claims 1-3, characterized in that, Before the gaseous material is fed into the centrifuge in S2, a pressure-stabilized injection step is also included. The pressure-stabilized injection step includes buffering and stabilizing the vaporized gaseous material to control the injection pressure to be lower than the vaporization pressure, and controlling the feed flow rate through a mass flow meter.

5. A method for the end purification and centrifugal separation of crude hexafluorouranium in a full dry process uranium purification conversion process according to claim 4, characterized in that, In the pressure stabilization injection step, the pressure after buffer stabilization is controlled at 0.08 to 0.25 MPa.

6. A method for the end purification and centrifugal separation of crude uranium hexafluoride in a full dry process uranium purification conversion process according to claim 5, characterized in that, The centrifuge chamber jacket temperature control in S2 is 50-80℃, the internal operating pressure is 0.05-0.2MPa, the centrifuge speed is 6000-15000r / min, and it is maintained in a gas phase state throughout the process.

7. A method for the end purification and centrifugal separation of crude uranium hexafluoride in a full dry process uranium purification conversion process according to claim 6, characterized in that, S3 includes regulating valves and flow meters installed on the light phase outlet and heavy phase outlet pipelines respectively. By adjusting the opening of the two outlet valves, the flow ratio of the light phase volumetric flow rate to the total feed volumetric flow rate is controlled to be 0.2 to 0.

6.

8. A method for the end purification and centrifugal separation of crude hexafluorouranium in a full dry process uranium purification conversion process according to claim 1, characterized by, S2 includes controlling the average residence time of gaseous materials in the centrifuge to 1-3 minutes by adjusting the feed volume flow rate.

9. The method for end-stage purification and centrifugal separation of crude uranium hexafluoride in a dry uranium purification and conversion process according to claim 1, characterized in that, The purified uranium hexafluoride enriched phase described in S3 is collected after being cooled and solidified by a condenser. The light impurity enriched phase is then recovered by condensation, washed with alkaline solution, and discharged harmlessly.

10. The method for end-stage purification and centrifugal separation of crude uranium hexafluoride in a dry uranium purification and conversion process according to claim 1, characterized in that, This includes using multi-stage centrifuge cascade separation to meet different purity requirements.

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