Device and method for treating and recycling uranium-containing fluorinated residues

Abstract

The invention discloses a device and method for treating and recycling uranium-containing fluorinated residues, the device comprises a plasma source, a reaction cavity and a material boat, plasma is generated in the plasma source and conveyed into the reaction cavity, the material boat is placed in the reaction cavity, and the uranium-containing fluorinated residues are located in the material boat. The recycling method comprises the following steps that S1, the blocky uranium-containing fluorinated residues are crushed, ground and then dried; s2, fluorine plasma is generated in the plasma source, and continuous generation of the fluorine plasma is maintained; s3, the generated fluorine plasma enters the reaction cavity and makes contact with uranium-containing fluorinated residue powder in the material boat, and uranium hexafluoride is generated; and S4, the generated uranium hexafluoride is collected. The device disclosed by the invention is compact, simple in structure and easy to operate, and effectively avoids the influence of a complex ion generation environment on a fluorination reaction process.

Description

Technical Field

[0001] This invention relates to the field of uranium-containing residue treatment technology, and specifically to an apparatus and method for treating and recovering uranium-containing fluorinated residues. Background Technology

[0002] The process of converting natural uranium into uranium hexafluoride using a fluorination reactor generates a large amount of uranium-containing fluorinated residue. Theoretical analysis and actual measurements show that the main components of the fluorinated residue are uranium intermediates, including UF5, U2F9, and U4F17. It also contains fluorides containing metallic impurities such as Fe, Cu, and Ni, making its composition complex and difficult to handle. Due to the relatively small domestic uranium hexafluoride production capacity in the early stages, the amount of uranium-containing fluorinated residue generated was also relatively small, and it was mostly handled through sealed temporary storage in containers. Systematic research on uranium recovery technology from the fluorinated residue was not conducted. With the rapid development of my country's nuclear industry, uranium hexafluoride production capacity has greatly increased, and the amount of uranium-containing fluorinated residue generated has also increased accordingly. The large accumulation of uranium-containing fluorinated residue not only results in a significant waste of nuclear materials but also poses certain environmental risks. Therefore, the recovery of uranium from the fluorinated residue can improve the utilization rate of uranium resources and reduce the cost of temporary storage and maintenance of the fluorinated residue, thereby improving economic efficiency and alleviating environmental pressure.

[0003] Currently, the main process for treating uranium-containing fluorinated residues abroad is the dry recovery process. This involves crushing the solid fluorinated residue and then using it as part of the fluorination feed to continue the fluorination reaction and recover the uranium. Dry recovery processes have the advantages of short process length and low secondary waste generation, but the resulting ash residue is difficult to remove and crush. With the widespread application of plasma technology in various fields, especially in industrial manufacturing and the electronics and semiconductor industries, plasma technology utilizes the high reactivity of ions for material processing and energy conversion. Focusing on the nuclear field, plasma technology can be used not only for nuclear waste treatment but also for fluorination reactions in dry reprocessing. For example, fluoride ions generated by the ionization of fluorine gas have higher reactivity than fluorine gas itself, and their participation in the fluorination reaction of uranium-containing fluorinated residues offers unique advantages over traditional methods, such as lower energy consumption and higher efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide an apparatus and method for the treatment and recovery of uranium-containing fluorinated residues, utilizing plasma technology to recover uranium from the residues.

[0005] The technical solution of the present invention is as follows: an apparatus for the treatment and recovery of uranium-containing fluorinated residue includes a plasma source, a reaction chamber, and a material boat. Plasma is generated in the plasma source and transported to the reaction chamber. The material boat is placed in the reaction chamber, and the uranium-containing fluorinated residue is located in the material boat.

[0006] The plasma source is equipped with a cooling circulation system.

[0007] One side of the plasma source is the gas supply end, and the other side is the plasma extraction end. There is a dielectric barrier discharge window on each side of the gas supply end, and the two dielectric barrier discharge windows are connected to the positive and negative electrodes respectively. The gas supply end is connected to the gas supply end face matching section, and the plasma extraction end is connected to the plasma extraction end face matching section. There is a vacuum arc ignition cavity between the gas supply end face matching section and the plasma extraction end face matching section. Ferrite is wrapped around the outside of the vacuum arc ignition cavity, and the plasma extraction end is connected to the entrance of the reaction cavity.

[0008] There are two vacuum arc ignition cavities, one on the left and one on the right. Each vacuum arc ignition cavity has three turns of ferrite wound around it, for a total of six ferrite pieces. The two ferrite pieces on the left and right are grouped together and connected to the positive and negative electrodes respectively to discharge, thereby generating plasma in the vacuum arc ignition cavity.

[0009] The outer end of the ferrite body is secured with a long straight tie rod.

[0010] The vacuum arc ignition cavity 6 is a six-segment cavity, each corresponding to a ferrite block, and is insulated.

[0011] The material boat is located in the fluorination reaction zone inside the reaction chamber. One end of the material boat is equipped with a support leg made of Monel400 material, and the tilt angle is 15.5°.

[0012] The surface of the reaction chamber is fitted with multiple flange-type interfaces for installing a pressure monitoring system and a viewing window, which is made of sapphire.

[0013] A method for treating and recovering uranium-containing fluoride residues includes the following steps:

[0014] S1: Crush, grind, and dry the blocky uranium-containing fluoride residue;

[0015] S2: Fluorine plasma is generated within the plasma source, and the continuous generation of fluorine plasma is maintained.

[0016] S3: The generated fluorine plasma enters the reaction chamber and comes into contact with the uranium-containing fluoride residue powder in the material boat to produce uranium hexafluoride;

[0017] S4: Collect the generated uranium hexafluoride.

[0018] In step S2, the entire device is first evacuated and replaced with argon gas through the gas supply end; then argon and fluorine gas are introduced through the gas supply end, followed by arc ignition discharge, and the inlet flow rates of argon and fluorine gas are adjusted respectively to finally form a stable fluorine plasma.

[0019] The significant advantage of this invention lies in its applicability to the fluorination treatment of uranium-containing fluorination residues. The device employs a modular design, resulting in a compact, simple, and easy-to-operate system. The plasma source utilizes a combination of dielectric barrier (DBD) and inductively coupled plasma (ICP) to ensure high-efficiency plasma discharge. The independent design of the reaction chamber separates the plasma generation zone from the fluorination reaction zone, effectively avoiding the influence of the complex ion generation environment on the fluorination process. Furthermore, the sloping elliptical material boat design meets practical application requirements, maximizing both the material distribution area and the ion contact area, thus significantly improving reaction efficiency.

[0020] This method is applicable to the fluorination residue generated during the preparation of uranium hexafluoride in traditional high-temperature fluorination reactors. It combines plasma technology with the fluorination reaction, utilizing the stronger reactivity of fluoride ions to recover uranium from the residue. This method offers advantages such as a short process flow, high fluorination rate, and low reaction temperature. Furthermore, the effective recovery of uranium from the fluorination residue improves the utilization efficiency of uranium resources, reduces environmental pressure, and yields significant economic benefits. Attached Figure Description

[0021] Figure 1 Schematic diagram of plasma source;

[0022] Figure 2 Schematic diagram of plasma source;

[0023] Figure 3 Half-section front view of a plasma source;

[0024] Figure 4 Schematic diagram of vacuum arc ignition cavity;

[0025] Figure 5 Schematic diagram of the reaction chamber;

[0026] Figure 6 Schematic diagram of a feeding boat.

[0027] The markings in the diagram and their corresponding component names are as follows:

[0028] 1 is the gas supply end, 2 is the gas supply end face matching section, 3 is ferrite, 4 is the plasma extraction end, 5 is the plasma extraction end face matching section, 6 is the vacuum arc ignition cavity, 7 is the dielectric barrier discharge window; 11 is the plasma source, 12 is the reaction cavity, and 13 is the material boat. Detailed Implementation

[0029] Many specific details are set forth in the following description to provide a full understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this application; therefore, this application is not limited to the specific embodiments disclosed below.

[0030] The terminology used in one or more embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of one or more embodiments of this application. The singular forms “a,” “the,” and “the” used in one or more embodiments of this application and in the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” used in one or more embodiments of this application refers to and includes any or all possible combinations of one or more associated listed items.

[0031] It should be understood that although the terms first, second, etc., may be used to describe various information in one or more embodiments of this application, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, first may also be referred to as second without departing from the scope of one or more embodiments of this application, and similarly, second may also be referred to as first.

[0032] The specific technical content of the present invention will now be described with reference to the accompanying drawings;

[0033] An apparatus for treating and recovering uranium-containing fluoride residue includes a plasma source 11, a reaction chamber 12, and a material boat 13. Plasma is generated in the plasma source 11 and transported into the reaction chamber 12. The material boat 13 is placed inside the reaction chamber 12, and the uranium-containing fluoride residue is located within the material boat 13. The plasma reacts with the uranium-containing fluoride residue to recover uranium hexafluoride generated from the uranium-containing fluoride residue.

[0034] Specifically, the plasma source 11 is equipped with a cooling circulation system for cooling. This system is installed at the power circuit board, where heat generation is highest, and at both ends of the plasma source, utilizing a circulating water tank to drive the flow of liquid within the cooling device. Testing has shown that the plasma device maintains a temperature below 30°C throughout operation, ensuring long-term stable operation.

[0035] Specifically, the generated uranium hexafluoride is collected using a two-stage cold trap connected in series.

[0036] like Figure 1 , 2 As shown in Figure 3, the plasma source 11 has a gas supply end 1 on one side and a plasma extraction end 4 on the other side. There is a dielectric barrier discharge window 7 on each side of the gas supply end 1, and the two dielectric barrier discharge windows 7 are connected to the positive and negative electrodes respectively, forming a circuit. The gas supply end 1 is connected to the gas supply end face matching section 2, and the plasma extraction end 4 is connected to the plasma extraction end face matching section 5. There is a vacuum arc ignition cavity 6 between the gas supply end face matching section 2 and the plasma extraction end face matching section 5. Ferrite 3 is wound around the outside of the vacuum arc ignition cavity 6.

[0037] Specifically, there are two vacuum arc-starting cavities 6, one on the left and one on the right. Each vacuum arc-starting cavity 6 has three turns of ferrite 3 wound around it, for a total of six ferrite pieces. The two ferrite pieces 3 on the left and right are grouped together and connected to the positive and negative electrodes respectively to discharge, thereby generating plasma in the vacuum arc-starting cavity 6.

[0038] Specifically, the outer end of ferrite 3 is secured with a long straight tie rod.

[0039] like Figure 4 As shown, the vacuum arc-starting cavity 6 has a circular loop structure. To prevent the cavity from forming an induced current loop in the alternating magnetic field, the vacuum arc-starting cavity 6 is designed as a six-segment cavity, corresponding to six ferrite blocks, and is insulated. The cavity connection interfaces are designed with concave and convex shapes for easy connection and assembly. All edges of the internal cavities are designed with rounded transitions to reduce losses during plasma transport. Because F ions and F atoms in the plasma have strong oxidizing properties, the cavity interior needs to undergo anodizing treatment to form a dense ceramic layer to prevent the oxidation effect of F ions and F atoms on the cavity.

[0040] The plasma extraction terminal 4 is connected to the inlet of the reaction chamber 12;

[0041] like Figure 5 As shown, the reaction chamber 12 is a cylindrical structure with a diameter of 100mm. Multiple flange-type interfaces are installed on its surface for installing pressure monitoring systems and viewing windows. Considering the complex composition of the atmosphere inside the chamber, the viewing windows are made of sapphire material.

[0042] like Figure 6 As shown, the material boat 13 is located in the fluorination reaction zone within the reaction chamber 12. The entire material boat 13 is made of Monel 400. One end of the material boat 13 is equipped with a support leg to maximize the tilt angle while preventing material slippage due to excessive tilt. Based on the height of the support leg and the tilt angle, the length of the material boat 13 is calculated using sine trigonometric functions. Combined with the elliptical design of the material boat, the final design of the reaction material boat is as follows: Figure 6 As shown, the long diameter of the material boat is 300mm, the short diameter is 100mm, the support leg height is 80mm, and the inclination angle of the material boat is 15.5°.

[0043] A method for treating and recovering uranium-containing fluoride residues includes the following steps:

[0044] S1: Material Pretreatment Scheme: Due to the limitations of traditional uranium hexafluoride preparation equipment and process conditions, the uranium-containing fluoride residue that adheres to the inner wall of the reactor after the reaction is mostly in block form after processing. This prevents the uranium encased inside from directly participating in the fluorination reaction, necessitating material pretreatment. Therefore, the blocky uranium-containing fluoride residue needs to be crushed and further refined into powder through grinding to ensure that the uranium element inside the residue is fully exposed. The ground uranium-containing fluoride residue is then dried to remove any moisture present inside the residue.

[0045] S2: Plasma is generated in plasma source 11, and then an induction coil is added to maintain the continuous generation of plasma.

[0046] The specific procedure is as follows: First, the entire device is evacuated, and then argon gas is introduced through gas supply end 1 to remove impurities. Argon and fluorine gas are introduced through gas supply end 1, then the power is turned on, the power parameters and gas flow rate are adjusted, and arc discharge is initiated. After successful argon ionization, the gas flow rates of argon and fluorine are adjusted separately to ultimately form a stable fluorine plasma. Throughout the ionization process, an ion monitoring device is used to monitor the plasma density to guide the adjustment of discharge parameters and ensure that the plasma density generated by the excitation is maximized.

[0047] S3: The generated fluorine plasma enters the reaction chamber 12. Since the reaction chamber 12 has a certain length, the plasma has a certain transport distance. Therefore, the fluorination reaction zone in the reaction chamber 12 is separated from the plasma generation zone, avoiding the influence of the complex environment of the plasma generation zone on the fluorination reaction. The fluorine plasma generated by the ion source is carried by the gas to the fluorination reaction zone, where it comes into contact with the fluorination residue powder in the boat 13, thereby undergoing a fluorination reaction to produce uranium hexafluoride.

[0048] S4: Based on the physicochemical properties of uranium hexafluoride, a freezing method is used to collect the uranium hexafluoride produced by fluorination. Before the fluorination reaction begins, the cold trap is cooled by liquid nitrogen. The cold trap is arranged in a two-stage series configuration. The first-stage cold trap collects most of the uranium hexafluoride, and the second-stage cold trap acts as a backup trap to cool and collect the uranium hexafluoride that escapes from the first-stage cold trap.

[0049] S5: Because fluorine gas is used in the fluorination reaction, the exhaust gas passes through two-stage sodium fluoride traps to adsorb any trace products that may be generated, two-stage charcoal traps to burn off excess fluorine gas, and complexing liquid to wash off unburned gas. Each stage is treated individually to ensure safe exhaust gas emissions.

[0050] The method for plasma fluorination treatment of uranium-containing fluorinated residues described in this invention involves pre-treating the lumpy material by pulverizing and drying it, ionizing the mixed gas and maintaining stable plasma through a plasma excitation system, adjusting parameters such as gas flow rate, gas ratio, and output power during the process, and monitoring plasma density using a microwave diagnostic device. A fluorination reaction system brings the plasma into contact with the fluorinated residues, initiating a fluorination reaction. A cold trap collection system collects the uranium hexafluoride produced during fluorination by freezing. A tail gas treatment system treats the reaction waste gas. In summary, by utilizing plasma in the fluorination reaction and adjusting various parameters, the method ultimately achieves the recovery of uranium from uranium-containing fluorinated residues.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0052] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0053] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0054] The preferred embodiments disclosed above are merely illustrative of this application. The optional embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this application. These embodiments are selected and specifically described in this application to better explain the principles and practical applications of this application, thereby enabling those skilled in the art to better understand and utilize this application.

Claims

1. An apparatus for the treatment and recovery of uranium-containing fluoride residues, characterized in that: It includes a plasma source (11), a reaction chamber (12), and a material boat (13). The plasma source (11) generates plasma and delivers it to the reaction chamber (12). The material boat (13) is placed in the reaction chamber (12), and the uranium-containing fluorinated residue is located in the material boat (13).

2. The apparatus for treating and recovering uranium-containing fluoride residue according to claim 1, characterized in that: The plasma source (11) is equipped with a cooling circulation system.

3. The apparatus for treating and recovering uranium-containing fluoride residue according to claim 1, characterized in that: One side of the plasma source (11) is the gas supply end (1), and the other side is the plasma extraction end (4). There is a dielectric barrier discharge window (7) on each side of the gas supply end (1), and the two dielectric barrier discharge windows (7) are connected to the positive and negative electrodes respectively. The gas supply end (1) is connected to the gas supply end face matching section (2), and the plasma extraction end (4) is connected to the plasma extraction end face matching section (5). There is a vacuum arc ignition cavity (6) between the gas supply end face matching section (2) and the plasma extraction end face matching section (5). Ferrite (3) is wrapped around the outside of the vacuum arc ignition cavity (6). The plasma extraction end (4) is connected to the entrance of the reaction cavity (12).

4. The apparatus for treating and recovering uranium-containing fluoride residue according to claim 3, characterized in that: There are two vacuum arc ignition cavities (6) on the left and right sides, and each vacuum arc ignition cavity (6) is wrapped with three turns of ferrite (3), for a total of six ferrites. The two ferrites (3) on the left and right sides are a group, connected to the positive and negative electrodes respectively, and discharge to generate plasma in the vacuum arc ignition cavity (6).

5. The apparatus for treating and recovering uranium-containing fluoride residue according to claim 3, characterized in that: The outer end of the ferrite (3) is fixed by a long straight tie rod.

6. The apparatus for treating and recovering uranium-containing fluoride residue according to claim 4, characterized in that: The vacuum arc ignition cavity (6) is a six-segment cavity, each corresponding to a ferrite block, and is insulated.

7. The apparatus for treating and recovering uranium-containing fluoride residue according to claim 6, characterized in that: The material boat (13) is located in the fluorination reaction zone inside the reaction chamber (12). One end of the material boat (13) is equipped with a support leg. The material is Monel400 and the tilt angle is 15.5°.

8. The apparatus for treating and recovering uranium-containing fluoride residue according to claim 7, characterized in that: Multiple flange-type interfaces are installed on the surface of the reaction chamber (12) for installing a pressure monitoring system and a viewing window, which is made of sapphire.

9. A method for treating and recovering uranium-containing fluoride residue, characterized in that: Includes the following steps: S1: Crush, grind, and dry the blocky uranium-containing fluoride residue; S2: Fluorine plasma is generated in the plasma source (11) and the continuous generation of fluorine plasma is maintained. S3: The generated fluorine plasma enters the reaction chamber (12) and comes into contact with the uranium-containing fluoride residue powder in the material boat (13) to produce uranium hexafluoride; S4: Collect the generated uranium hexafluoride.

10. The method for treating and recovering uranium-containing fluoride residue according to claim 9, characterized in that: In S2, the entire device is first evacuated and replaced with argon gas through the gas supply end (1); then argon and fluorine gas are introduced through the gas supply end (1), followed by arc discharge. The inlet flow rates of argon and fluorine gas are adjusted respectively, and finally a stable fluorine plasma is formed.

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