Method and apparatus for processing used ion exchange resins

Abstract

To provide a method for processing used ion exchange resin which generates less secondary wastes and a processor with a simple configuration for processing used ion exchange resin.SOLUTION: The method for processing used ion exchange resin includes the step of applying an atmosphere non-equilibrium plasma to the used ion exchange resin.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a method and apparatus for treating used ion exchange resins.

Background Art

[0002] In nuclear power plants, ion exchange resins are used in purification facilities such as reactor water purification systems and waste liquid treatment systems. The used ion exchange resins used in such purification facilities adsorb radioactive substances and have a high radioactivity concentration, so a safe and inexpensive treatment technology is required. As treatment methods for used ion exchange resins, treatment technologies such as a complete mineralization method using supercritical water, a method of partially separating adsorbed elements, a method using inductively coupled plasma (ICP) or thermal plasma (Patent Document 1, Patent Document 2), etc. have been proposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the complete mineralization method using supercritical water, high temperature and high pressure conditions are required, so there is a problem that a large-scale device is needed. Also, in the method of partially separating adsorbed elements, there is a problem that waste liquid is generated as secondary waste after resin treatment, and the treatment cost becomes high because further treatment is required. Further, in the method using inductively coupled plasma (ICP) or thermal plasma, radioactive nuclides and corrosive gases volatilize due to treatment at high temperature, and exhaust gas treatment is required, resulting in high treatment costs.

[0005] The present invention was made to solve the above-mentioned conventional problems, and its objective is to provide a method and apparatus for processing used ion exchange resins that has a simple apparatus configuration and generates less secondary waste. [Means for solving the problem]

[0006] The method for processing used ion exchange resin according to the embodiment is a method for processing used ion exchange resin, characterized by comprising the step of irradiating the used ion exchange resin with atmospheric pressure non-equilibrium plasma.

[0007] The spent ion exchange resin processing apparatus of the embodiment is a spent ion exchange resin processing apparatus that processes spent ion exchange resin, and is characterized by comprising: an atmospheric pressure non-equilibrium plasma generation mechanism for generating atmospheric pressure non-equilibrium plasma; and an atmospheric pressure non-equilibrium plasma irradiation unit for irradiating the spent ion exchange resin contained therein with the atmospheric pressure non-equilibrium plasma generated by the atmospheric pressure non-equilibrium plasma generation mechanism. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a method and apparatus for processing used ion exchange resins that have a simple apparatus configuration and generate a small amount of secondary waste. [Brief explanation of the drawing]

[0009] [Figure 1] A flowchart showing the processing flow of the treatment method for used ion exchange resin according to the first embodiment. [Figure 2] A schematic diagram showing the general configuration of a processing device for used ion exchange resin according to the first embodiment. [Figure 3] A flowchart showing the processing flow of the treatment method for used ion exchange resin according to the second embodiment. [Figure 4] A flowchart showing the processing flow of the treatment method for used ion exchange resin according to the third embodiment. [Figure 5]A flowchart showing the processing flow of the treatment method for used ion exchange resin according to the fourth embodiment. [Figure 6] This figure schematically shows an example of a sheet-like molded shape for used ion exchange resin according to the fourth embodiment. [Figure 7] This figure shows an example of a used ion exchange resin molded into a sheet shape with an uneven surface according to the fourth embodiment. [Figure 8] This figure schematically shows an example of a pelletized molded shape for used ion exchange resin according to the fourth embodiment. [Figure 9] This figure schematically shows a modified configuration of the processing apparatus for used ion exchange resin shown in Figure 2. [Figure 10] This figure schematically shows a modified configuration of the processing apparatus for used ion exchange resin shown in Figure 9. [Modes for carrying out the invention]

[0010] The following describes a method and apparatus for processing spent ion exchange resin according to the embodiment, with reference to the drawings. In the embodiment described below, we will describe the processing of spent ion exchange resin used in purification equipment such as reactor water purification systems and wastewater treatment systems of nuclear power plants, to which radioactive materials have been adsorbed. However, the same method can be applied to the processing of spent ion exchange resin to which heavy metal elements other than radioactive materials have been adsorbed.

[0011] (First Embodiment) The processing method and processing apparatus for used ion exchange resin according to the first embodiment will be described below with reference to Figures 1 and 2. Figure 1 is a flowchart showing the processing flow of the processing method for used ion exchange resin according to this embodiment, and Figure 2 is a schematic diagram showing the general configuration of the processing apparatus for used ion exchange resin according to this embodiment.

[0012] As shown in Figure 1, in this embodiment, used ion exchange resin 101, which has been ion-exchanged with radioactive material, is irradiated with atmospheric pressure non-equilibrium plasma 102. This atmospheric pressure non-equilibrium plasma is a plasma in which only the electron temperature is high (for example, tens of thousands of degrees Celsius or higher), while the ion temperature and gas temperature are at room temperature. It can be generated by applying electrical energy in a gas atmosphere such as air. In this case, for example, plasmas such as glow discharge plasma, barrier discharge plasma, arc discharge plasma, high-frequency induction plasma, and corona plasma can be used.

[0013] As shown in Figure 2, the treatment apparatus for used ion exchange resin consists of a used ion exchange resin storage tank 1, an atmospheric pressure non-equilibrium plasma generator 3, an atmospheric pressure non-equilibrium plasma irradiation unit 4, a residue recovery unit 5, an exhaust gas treatment apparatus 6, and a transfer line 2 connecting the used ion exchange resin storage tank 1, the atmospheric pressure non-equilibrium plasma irradiation unit 4, and the residue recovery unit 5. The transfer line 2 consists of a transport mechanism that physically transports the used ion exchange resin 101 and its residue, such as a screw conveyor or a belt conveyor.

[0014] The used ion exchange resin is transferred from the used ion exchange resin storage tank 1 to the atmospheric pressure non-equilibrium plasma irradiation unit 4 via the transfer line 2. There, it is irradiated with atmospheric pressure non-equilibrium plasma generated by the atmospheric pressure non-equilibrium plasma generator 3. In the atmospheric pressure non-equilibrium plasma generator 3, a predetermined gas, such as air or a gas with other gases added to it, is flowed. This excites gas molecules such as oxygen contained in the gas, generating active species such as ozone and hydroxyl radicals, and the used ion exchange resin 101 comes into contact with these active species contained in the gas.

[0015] Therefore, as shown in Figure 1, the used ion exchange resin 101 is separated into used ion exchange resin residue 103 and decomposition gas 104 by irradiation with atmospheric pressure non-equilibrium plasma 102 for a predetermined time. The used ion exchange resin residue 103 is transferred to the residue recovery unit 5 via the transfer line 2 shown in Figure 2 and disposed of. On the other hand, the decomposition gas 104 is recovered by the exhaust gas treatment device 6 and rendered harmless.

[0016] In the atmospheric pressure non-equilibrium plasma irradiation 102 of the used ion exchange resin 101 described above, active species such as ozone and hydroxyl radicals described above act, and the carbon bonds and the bonds of the ion exchange groups constituting the used ion exchange resin 101 are broken. An ion exchange group and a radioactive substance are desorbed from the used ion exchange resin 101, and carbon dioxide and the like are generated as gas components.

[0017] As described above, according to the first embodiment, it is possible to use a device with a simple configuration without using a device that requires high temperature, high pressure, and high vacuum, and the atmospheric pressure non-equilibrium plasma irradiation 102 is performed on the used ion exchange resin 101, and an ion exchange group and a radioactive substance are desorbed from the used ion exchange resin 101, and the volume reduction or the radiation dose of the used ion exchange resin 101 can be reduced.

[0018] In general, the resin of the used ion exchange resin 101 has a strong bond, and when trying to reduce the volume by compression, there is a limit to the volume reduction due to the springback of the resin. However, by cutting the bond of the resin by the atmospheric pressure non-equilibrium plasma irradiation 102, the springback of the resin can be suppressed, and the volume reduction of the waste by compression becomes easy. Further, when the radioactive substance is separated by the cutting of the bond, the radiation dose of the used ion exchange resin residue 103 decreases, and the treatment cost can be reduced. In some cases, the used ion exchange resin residue 103 can also be separated into a residue with high radioactivity and a residue with low radioactivity and disposed of separately.

[0019] (Second Embodiment) Hereinafter, a method for treating a used ion exchange resin according to the second embodiment will be described with reference to FIG. 3. FIG. 3 is a flowchart showing the processing flow of the method for treating a used ion exchange resin according to the present embodiment.

[0020] As shown in Figure 3, in this embodiment, before irradiating the used ion exchange resin 101 with atmospheric pressure non-equilibrium plasma 102, a pulverization treatment 105 is performed to pulverize the used ion exchange resin 101 to a size of, for example, several hundred microns or less. As a method for pulverizing the used ion exchange resin, for example, an emulsification method, or a method using a rod mill, ball mill, vibrating rod mill, vibrating ball mill, etc., can be used.

[0021] As described above, in this embodiment, by performing the pulverization process 105, the particle size of the used ion exchange resin 101 is reduced, and its surface area is increased. This allows the atmospheric pressure non-equilibrium plasma to be applied more efficiently, thereby improving the efficiency of the process.

[0022] (Third embodiment) The processing method for used ion exchange resin according to the third embodiment will be described below with reference to Figure 4. Figure 4 is a flowchart showing the processing flow of the processing method for used ion exchange resin according to this embodiment.

[0023] As shown in Figure 4, in this embodiment, before the used ion exchange resin 101 is subjected to atmospheric pressure non-equilibrium plasma irradiation 102, the used ion exchange resin 101, which has been pulverized by the pulverization process 105, is subjected to an impregnation process 106 in which a liquid is impregnated into the used ion exchange resin 101. In this impregnation process 106, for example, water, hydrogen peroxide solution, etc., can be used as the liquid to impregnate.

[0024] As described above, in this embodiment, by performing an impregnation treatment 106 in which a liquid is impregnated into the used ion exchange resin 101 whose particle size has been finened by the pulverization treatment 105, when atmospheric pressure non-equilibrium plasma irradiation 102 is performed, active species such as molecules constituting the impregnated liquid are generated on the surface of the used ion exchange resin 101. As a result, the generated active species efficiently contribute to the bond cleavage of the used ion exchange resin 101, thereby improving the efficiency of the treatment.

[0025] (Fourth Embodiment) The treatment method for used ion exchange resin according to the fourth embodiment will be described below with reference to Figure 5. Figure 5 is a flowchart showing the treatment flow of the treatment method for used ion exchange resin according to this embodiment.

[0026] As shown in Figure 5, in this embodiment, before irradiating the used ion exchange resin 101 with atmospheric pressure non-equilibrium plasma 102, a molding process 107 is performed to mold the used ion exchange resin 101 into a predetermined shape, for example, into a sheet shape as shown in Figure 6.

[0027] The used ion exchange resin 101 to be molded may also be granulated by a pulverization process 105. The thickness of the molded sheet is preferably 1 mm or less, and more preferably 0.1 mm or less.

[0028] In atmospheric pressure non-equilibrium plasma, the required inter-electrode distance and the range of active species generation differ depending on the type of gas used, so the sheet thickness can be set according to the type of gas used. Furthermore, heating and fusion can be performed during molding. The sheet-shaped used ion exchange resin can be transported to the atmospheric pressure non-equilibrium plasma irradiation section 4 by a belt conveyor or similar means. The sheet-shaped used ion exchange resin can also be used as a dielectric for barrier discharge. In this case, the efficiency of exposure to the plasma increases, and the processing time can be shortened. The dielectric can be combined with glass or other materials, and its shape is not limited to a sheet.

[0029] The molded form of the used ion exchange resin in this embodiment can be modified as follows. Figure 7 shows an example of molding in which a mold or the like is used when molding into a sheet shape to create irregularities on the surface and increase the surface area to which atmospheric pressure non-equilibrium plasma is irradiated. Figure 8 shows an example of molding the used ion exchange resin into a pellet shape. Molding can also be performed by pressurization, and water may be added to improve processability, or polymers that decompose in plasma treatment, such as PVA (polyvinyl alcohol), CMC (calximethylcellulose), gelatin, or dextrin may be added as binders.

[0030] As described above, in this embodiment, by molding the used ion exchange resin 101, the scattering of the used ion exchange resin 101 by the gas flow of the atmospheric pressure non-equilibrium plasma is suppressed. This suppresses the adhesion of the used ion exchange resin 101 to the electrode surface of the atmospheric pressure non-equilibrium plasma generator 3, etc. Furthermore, fluctuations in irradiation time and irradiation distance are suppressed, and processing of the used ion exchange resin 101 under uniform conditions is possible, making it possible to process under constant conditions without changing the irradiation time or irradiation distance.

[0031] Next, a modified example of the used ion exchange resin processing apparatus shown in Figure 2 will be described with reference to Figures 9 and 10. In Figures 9 and 10, parts corresponding to the used ion exchange resin processing apparatus shown in Figure 2 are denoted by the same reference numerals, and redundant explanations are omitted.

[0032] Figure 9 is a schematic diagram showing the general configuration of a modified example of a spent ion exchange resin processing apparatus. As shown in Figure 9, this spent ion exchange resin processing apparatus is equipped with a temperature control mechanism 7 in the atmospheric pressure non-equilibrium plasma irradiation section 4, allowing the temperature of the atmospheric pressure non-equilibrium plasma irradiation section 4 to be controlled.

[0033] The controlled temperature of the atmospheric pressure non-equilibrium plasma irradiation section 4 by this temperature control mechanism 7 is preferably several hundred degrees Celsius, for example, around 300 degrees Celsius. Even when a high temperature is used, it is preferable that it is below the melting point of a compound of Cs-137, a highly volatile radionuclide, which is 600 degrees Celsius. Furthermore, as shown in Figure 10, the system can also be configured to include a radiation dose monitoring section 8.

[0034] As described above, when the atmospheric pressure non-equilibrium plasma irradiation unit 4 is equipped with a temperature control mechanism 7, heating the atmospheric pressure non-equilibrium plasma irradiation unit 4 improves the migration speed of the plasma-generated active species. This accelerates the oxidation reaction of the used ion exchange resin, thereby improving the processing speed. Furthermore, by enabling the monitoring of radiation levels in the radiation dose monitoring unit 8, safe processing can be carried out.

[0035] Although several embodiments of the present invention have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0036] 1... Used ion exchange resin storage tank, 2... Transfer line, 3... Atmospheric pressure non-equilibrium plasma generator, 4... Atmospheric pressure non-equilibrium plasma irradiation unit, 5... Residue recovery unit, 6... Exhaust gas treatment device, 7... Temperature control mechanism, 8... Radiation dose monitoring unit, 101... Used ion exchange resin, 102... Atmospheric pressure non-equilibrium plasma irradiation, 103... Used ion exchange resin residue, 104... Decomposition gas, 105... Grinding treatment, 106... Impregnation treatment, 107... Molding treatment.

Claims

1. A method for processing used ion exchange resins, A method for processing used ion exchange resin, characterized by comprising an atmospheric pressure non-equilibrium plasma irradiation step of irradiating the used ion exchange resin with atmospheric pressure non-equilibrium plasma generated from a gas containing air.

2. The method for processing used ion exchange resin according to claim 1, characterized in that, prior to the atmospheric pressure non-equilibrium plasma irradiation step, the used ion exchange resin is subjected to a pulverization step to finely granulate it.

3. The method for processing used ion exchange resin according to claim 2, characterized in that an impregnation process is performed between the pulverization process and the atmospheric pressure non-equilibrium plasma irradiation process, in which a predetermined liquid is impregnated into the granulated used ion exchange resin.

4. The method for processing used ion exchange resin according to claim 1 or 2, characterized in that, prior to the atmospheric pressure non-equilibrium plasma irradiation step, the used ion exchange resin is molded into a predetermined shape.

5. The method for processing used ion exchange resin according to claim 4, characterized in that, in the molding process, the used ion exchange resin is molded into a sheet shape or a sheet shape having irregularities on its surface.

6. The method for processing a used ion exchange resin according to Claim 1, characterized in that the atmospheric pressure non-equilibrium plasma irradiation step involves irradiating the used ion exchange resin with the atmospheric pressure non-equilibrium plasma to break the carbon bonds and ion exchange group bonds constituting the used ion exchange resin.

7. A processing apparatus for used ion exchange resins, which processes used ion exchange resins, A mechanism for generating atmospheric pressure non-equilibrium plasma, An atmospheric pressure non-equilibrium plasma irradiation unit that irradiates the used ion exchange resin contained inside with the atmospheric pressure non-equilibrium plasma generated from a gas containing air by the atmospheric pressure non-equilibrium plasma generation mechanism, A processing apparatus for used ion exchange resin, characterized by comprising the following:

8. A used ion exchange resin storage tank for containing the used ion exchange resin, A transfer line for transferring the used ion exchange resin from the used ion exchange resin storage tank to the atmospheric pressure non-equilibrium plasma irradiation unit, A residue recovery unit for containing used ion exchange resin residue generated in the atmospheric pressure non-equilibrium plasma irradiation unit, An exhaust gas treatment mechanism for treating the decomposition gas generated in the atmospheric pressure non-equilibrium plasma irradiation section, The apparatus for used ion exchange resin according to claim 7, characterized by comprising the above.

9. The apparatus for used ion exchange resin according to claim 7 or 8, characterized in that, in the atmospheric pressure non-equilibrium plasma generation mechanism, used ion exchange resin molded into a predetermined shape is used as a dielectric for barrier discharge.

10. The apparatus for used ion exchange resin according to claim 7 or 8, characterized in that the atmospheric pressure non-equilibrium plasma irradiation section has a temperature control mechanism.

11. The apparatus for used ion exchange resin according to claim 10, characterized in that the atmospheric pressure non-equilibrium plasma irradiation section has a radiation dose monitoring section.

12. The apparatus for processing used ion exchange resin according to claim 7, characterized in that the atmospheric pressure non-equilibrium plasma irradiation unit irradiates the used ion exchange resin with the atmospheric pressure non-equilibrium plasma to break the carbon bonds and ion exchange group bonds constituting the used ion exchange resin.

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