JP6100185B2 - Processing method and processing apparatus for used ion exchange resin - Google Patents

Description

  The present invention relates to a processing method and a processing apparatus for used ion exchange resins.

  At nuclear power plants, ion exchange resins are used for cooling water purification and waste liquid treatment. Radioactive substances are contained in the cooling water and waste liquid of nuclear power plants, and used ion exchange resins that adsorb these radioactive substances have relatively high radioactivity. For this reason, it is required to reduce the radioactivity by decomposing the used ion exchange resin that has adsorbed the radioactive substance and to reduce the capacity of the radioactive waste.

  In addition, ion exchange resins are used to detoxify industrial wastewater containing heavy metal elements. Industrial wastewater contains various heavy metal elements, and it is required to reduce the amount of waste when treating used ion exchange resin adsorbing these heavy metal elements as industrial waste.

  In addition, as a method for treating used ion exchange resins, a method of completely mineralizing a resin using supercritical water decomposition, hydrogen peroxide oxidation, or the like has been proposed (for example, see Patent Document 1). However, this method has a problem that a large-scale device is required or a large amount of secondary waste is generated. Further, a method of reducing the volume by disabling the ion exchange group of the used ion exchange resin with an oxidizing agent has been studied (for example, see Patent Document 2). However, this method requires an oxidizing agent or a chemical or an apparatus for neutralizing the waste liquid after the ion exchange group is disabled, and the processing steps and the processing apparatus may be complicated.

JP-A-10-324768 JP 2011-214971 A

  The present invention has been made in order to solve the above-described problems, and it is possible to simplify a treatment process and a treatment apparatus and reduce the amount of secondary waste generated, and a treatment method and treatment of a used ion exchange resin. An object is to provide an apparatus.

One aspect of the method for treating a used ion exchange resin of the present invention is a method for treating a used ion exchange resin for treating a used ion exchange resin adsorbed with a radionuclide or a heavy metal element. Exchange at 80 ° C. or higher and 90 ° C. or lower with an iron compound , hydrogen peroxide and ozone to desorb an ion exchange group which is an adsorption site of the radionuclide or heavy metal element of the used ion exchange resin And a separation step of separating the radionuclide or heavy metal element from the used ion exchange resin from which the radionuclide or heavy metal element has been desorbed.

One aspect of the processing apparatus for a used ion exchange resin of the present invention is a processing apparatus for a used ion exchange resin for processing a used ion exchange resin adsorbed with a radionuclide or a heavy metal element, wherein the used ion exchange resin is used. A decomposition tank containing therein an iron compound , hydrogen peroxide and ozone, and desorbing an ion exchange group which is an adsorption site of the radionuclide or heavy metal element of the ion exchange resin at 80 ° C. or higher and 90 ° C. or lower; A used ion exchange resin storage device for supplying the used ion exchange resin to the decomposition tank; a metal salt supply device for supplying the iron compound to the decomposition tank; and supplying the hydrogen peroxide to the decomposition tank A hydrogen peroxide supply device, an ozone supply device for supplying the ozone to the decomposition tank, and the used ion exchange tree from which the radionuclide or heavy metal element is desorbed. It is provided with the separator which isolate | separates the waste containing fat and the said radionuclide or a heavy metal element, and the volume reduction apparatus which reduces the said waste.

  According to the processing method and processing apparatus of the used ion exchange resin of this invention, a process process and a processing apparatus can be simplified and the generation amount of a secondary waste can be reduced.

The flowchart which shows the processing method of the used ion exchange resin of embodiment. (A) And (b) is a figure for demonstrating the principle of the processing method of the used ion exchange resin which concerns on embodiment. The schematic block diagram which shows the processing apparatus of the used ion exchange resin of embodiment. The graph which shows the relationship between the cobalt detachment | desorption rate and process conditions in an Example. The graph which shows the relationship between the cobalt desorption rate and processing temperature in an Example.

  Hereinafter, embodiments of a processing method and a processing apparatus for used ion exchange resins according to the present invention will be described with reference to the drawings.

  FIG. 1 is a flowchart showing a method of treating a used ion exchange resin according to this embodiment. FIG. 2 is a view for explaining the principle of the processing method of the used ion exchange resin according to the present embodiment.

  The processing target of the present embodiment is a used ion exchange resin used for purification of cooling water, waste liquid processing, or industrial wastewater processing at a nuclear power plant, for example. In the processing method and processing apparatus for the used ion exchange resin of this embodiment, in order to reduce the radiation dose of the used ion exchange resin, the radioactive substance (radionuclide) captured by the used ion exchange resin is removed. Alternatively, in order to reduce the amount of waste, heavy metal elements captured by the used ion exchange resin are removed.

  Specifically, in the ion exchange group elimination step S1 shown in FIG. 1, the radioactive material (radionuclide) or heavy metal element of the used ion exchange resin 100 using the metal salt 1, hydrogen peroxide 2 and ozone 3 is used. The ion exchange group which is the adsorption site is removed from the skeleton of the ion exchange resin. By allowing a small amount of metal salt 1 to coexist in the liquid phase in which hydrogen peroxide 2 and ozone 3 are dissolved, a hydroxy radical is generated, and the generated hydroxy radical is a functional group on which a radioactive substance (radionuclide) or heavy metal element is adsorbed. From the skeleton of the ion exchange resin.

  As shown in FIG. 2A, a radionuclide (or heavy metal element, the same applies hereinafter) 102 is adsorbed on the ion exchange group 101 of the used ion exchange resin (cation exchange resin) 100. Examples of such a radionuclide 102 include cobalt (Co-60) that provides a high dose rate to the used ion exchange resin 100.

In the ion exchange group elimination step (S1 in FIG. 1), this used ion exchange resin 100 is mixed with a metal salt 1, hydrogen peroxide 2 and ozone 3 in a liquid phase, for example, an aqueous solution, to form a radionuclide 102. In FIG. 2A, a cation exchange resin is shown as an example. As the used ion exchange resin 100, a cation exchange resin, Either an anion exchange resin or a mixed bed thereof may be used.

As the metal salt 1, a metal compound that reacts with the hydrogen peroxide 2 to generate a hydroxy radical is used. The metal salt 1 is not particularly limited as long as it is a metal compound that reacts with hydrogen peroxide 2 to generate a hydroxy radical, but is preferably an iron compound, and since it easily generates a hydroxy radical, for example, iron chloride ( It is preferred to use II). The iron compound is also suitable because it is abundant in the environment in which the ion exchange resin is used, such as sludge generated in the reactor water. In this case, the concentration of hydrogen peroxide 2 is a concentration at which ion exchange groups can be eliminated. For example, a mixture containing metal salt 1, hydrogen peroxide 2, ozone 3, and used ion exchange resin 100 is used. The total amount is about 3% by mass or less. The supply amount of the ozone 3 is not particularly limited as long as the ion exchange group can be eliminated, and is set to, for example, about 50 g / m ³ .

  Further, from the point of promoting the generation of hydroxy radicals, the treatment temperature in the ion exchange group elimination step S1 is preferably normal temperature (25 ° C.) or higher and 90 ° C. or lower, more preferably 60 ° C. or higher and 90 ° C. or lower. It is preferably about 80 ° C. The treatment time depends on the amount of used ion exchange resin 100 to be treated and the amount of adsorbed radionuclide 102, but is about 1 hour or more.

  In the ion exchange group desorption step S1, by using the metal salt 1, hydrogen peroxide 2 and ozone 3, the ion exchange group desorption performance can be improved without pressurization or decompression. Further, excellent ion exchange group elimination performance can be obtained without adding an acid or base as a pH adjuster for adjusting the pH of the treatment liquid. Therefore, it is possible to simplify a processing process and a processing apparatus.

  In this way, in the ion exchange group elimination step S1, it becomes possible to detach the radioactive substance (radionuclide) from the used ion exchange resin 100, and the used ion exchange resin 100 is made to be a low radioactive ion exchange resin (treatment). Used ion exchange resin 103).

  The treated ion exchange resin 103 that has undergone the ion exchange group elimination step S1 is in a state in which the radionuclide 102 has been released together with the ion exchange groups 101, as shown in FIG.

  Then, after desorption of the ion exchange group 101, in the solid-liquid separation step S2 shown in FIG. 1, the waste liquid 4 containing the radionuclide 102 desorbed from the used ion exchange resin 100 and the treated ion exchange after desorption of the radionuclide 102 are performed. The resin (ion exchange resin skeleton) 103 is separated.

  The waste liquid 4 containing the radionuclide 102 is treated by, for example, cement solidification after concentration or dilution as necessary. The treated ion exchange resin 103 is treated by cement solidification after volume reduction by incineration or the like.

FIG. 3 is a schematic configuration diagram of a processing apparatus used in the processing method of the present embodiment.
The processing apparatus 10 shown in FIG. 3 includes a decomposition tank 5 in which a used ion exchange resin 100, a metal salt 1, hydrogen peroxide 2, and ozone 3 are housed and reacted. Further, a used ion exchange resin storage tank 6 for storing the used ion exchange resin 100 and supplying it to the decomposition tank 5 is provided.

The processing apparatus 10 includes a metal salt supply device 7 that supplies the metal salt 1 to the decomposition tank 5, a hydrogen peroxide supply device 8 that supplies hydrogen peroxide 2, and an ozone supply device 9 that supplies ozone 3. It has. A solid-liquid separator 11 for separating the waste liquid 4 containing the radionuclide 102 desorbed together with the ion exchange groups 101 of the used ion exchange resin 100 and the treated ion exchange resin 103 is provided at the lower part of the decomposition tank 5. . The solid-liquid separator 11 is composed of a separation filter and the like.
Furthermore, the processing apparatus 10 includes a volume reduction device 12 that concentrates and reduces the volume of the waste liquid 4. The waste liquid 4 is reduced in volume by the volume reduction device 12 and then processed by, for example, cement solidification.

(Examples 1-6)
As an example of a radioactive substance and a heavy metal element, a resin on which cobalt was adsorbed was decomposed, and a test was performed to desorb a functional group on which cobalt was adsorbed.

  As a test resin, a generally used strong acid cation exchange resin was used. First, the test resin was immersed in a cobalt sulfate solution to adsorb cobalt. The amount of cobalt adsorbed on the test resin was calculated by measuring the cobalt concentration in the liquid phase before and after immersion.

The test resin adsorbing cobalt was placed in a decomposition tank, and in Example 1, hydrogen peroxide solution and iron (II) chloride were added and stirred while ozone gas was supplied. The supply amount of ozone gas is 50 g / m ³ , hydrogen peroxide is 2.8% by mass, and iron (II) chloride is iron equivalent to the total amount of the mixture containing iron (II) chloride, hydrogen peroxide, ozone and test resin. To 50 ppm. The liquid phase pH was not adjusted, and the test was conducted at a liquid phase temperature of 80 ° C. and atmospheric pressure, with a reaction time of 1 hour. The cobalt concentration in the liquid phase after the test was measured, and the cobalt desorption rate was determined using the cobalt adsorption amount.

The test resin was treated with 50 g / m ³ ozone only in Example 2. In Example 3, the treatment was performed with only 2.8% by mass of hydrogen peroxide. In Example 4, it was treated only with 50 ppm iron (II) chloride. Example 5 was treated with ozone at the above feed and hydrogen peroxide at the above concentrations. In Example 6, the treatment was performed in the presence of hydrogen peroxide and iron (II) chloride at the above concentrations.

  The results of the above test are shown in Table 1 together with the test conditions. Further, the relationship between the test conditions and the cobalt desorption rate is shown in the graph of FIG. 4 with the cobalt desorption rate as the vertical axis.

  From Table 1 and FIG. 4, when ozone, hydrogen peroxide, and iron (II) chloride were each acted alone, the cobalt desorption rate was less than 0.01%. Further, the desorption rate was less than 0.01% even under the condition where ozone and hydrogen peroxide coexisted. In addition, the desorption rate was 1% under the condition where hydrogen peroxide and iron (II) chloride coexist. On the other hand, when ozone, hydrogen peroxide, and iron (II) chloride were allowed to coexist, a desorption rate of 53% was shown. Thus, it can be seen that the cobalt desorption rate was improved by the coexistence of ozone, hydrogen peroxide, and iron (II) chloride.

(Examples 7 to 10)
Regarding the resin decomposition under conditions using ozone, hydrogen peroxide and iron (II) chloride, the ion exchange group elimination performance when the temperature was changed was investigated. In Examples 7 to 10, tests were performed under the same conditions as in Example 1 except that the temperatures were adjusted to 25 ° C., 60 ° C., 80 ° C., and 90 ° C., and the cobalt desorption rate was measured.

  The results are shown in Table 2 together with the test conditions. FIG. 5 shows the relationship between the test conditions and the cobalt desorption rate, with the cobalt desorption rate as the vertical axis.

  The desorption reaction became active as the temperature increased from 25 ° C., reaching 0.04% at 60 ° C. and 53% at 80 ° C., and the cobalt desorption rate decreased to 5% at 90 ° C. This is because although the amount of hydroxy radicals generated increases as the temperature rises, there is an optimum temperature for the generation of hydroxy radicals. Ozone, hydrogen peroxide, and iron (II) chloride can be obtained at approximately 80 ° C. When coexisting, the ion exchange resin was decomposed, and the functional group to which cobalt was adsorbed was efficiently eliminated.

  In the above test, the use of iron (II) chloride, hydrogen peroxide, and ozone improves the cobalt desorption rate without adding chemicals for pH adjustment. Therefore, according to the processing method of the present embodiment, it is not necessary to add a chemical agent for the decomposition treatment of the ion exchange resin, and the processing steps can be simplified. Further, the treatment is performed under atmospheric pressure, and the cobalt desorption rate is improved. Therefore, according to the processing method of the present embodiment, a device for adjusting the pressure is unnecessary, and the processing apparatus can be simplified. In this example, the test was carried out using cobalt. However, since the decomposition principle is a functional group elimination reaction, not only cobalt but also the used ion exchange resin adsorbed with radionuclides or heavy metal elements can be decomposed. Is possible.

  Thus, according to the processing method and processing apparatus of the used ion exchange resin of embodiment, a processing process and a processing apparatus can be simplified and the generation amount of a secondary waste can be reduced.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Metal salt, 2 ... Hydrogen peroxide, 3 ... Ozone, 4 ... Waste liquid, 5 ... Decomposition tank, 6 ... Ion exchange resin storage tank, 7 ... Metal salt supply apparatus, 8 ... Hydrogen peroxide supply apparatus, 9 ... Ozone Supply device, 10 ... treatment device, 11 ... solid-liquid separator, 12 ... volume reduction device, 100 ... ion exchange resin, 101 ... ion exchange group, 102 ... radionuclide, 103 ... treated ion exchange resin (ion exchange resin skeleton) ), S1 ... ion exchange group elimination step, S2 ... solid-liquid separation step.

Claims (5)

A method of treating a used ion exchange resin for treating a used ion exchange resin adsorbed with a radionuclide or a heavy metal element,
The used ion exchange resin is brought into contact with an iron compound , hydrogen peroxide, and ozone at 80 ° C. or more and 90 ° C. or less, and the ion exchange group that is the adsorption site of the radionuclide or heavy metal element of the used ion exchange resin. An ion exchange group elimination step for eliminating
A method for treating a used ion exchange resin, comprising: the used ion exchange resin from which the radionuclide or heavy metal element is desorbed and a separation step for separating the radionuclide or heavy metal element. In the ion exchange group elimination step, a hydroxy radical is generated by coexistence of the iron compound, the hydrogen peroxide and the ozone, and the ion exchange group is eliminated by the hydroxy radical. A method for treating a used ion exchange resin according to Item 1. The method for treating a used ion exchange resin according to claim 1 or 2 , wherein an acid or a base as a pH adjusting agent is not added in the ion exchange group elimination step. The used ion exchange resin treatment method according to any one of claims 1 to 3 , wherein the ion exchange group elimination step is performed under atmospheric pressure. A processing apparatus for used ion exchange resins for treating used ion exchange resins adsorbed with radionuclides or heavy metal elements,
The spent ion exchange resin, iron compound , hydrogen peroxide and ozone are housed inside, and the ion exchange group which is an adsorption site of the radionuclide or heavy metal element of the ion exchange resin at 80 ° C. or more and 90 ° C. or less. A decomposition tank for desorption,
A used ion exchange resin storage device for supplying the used ion exchange resin to the decomposition tank;
A metal salt supply device for supplying the iron compound to the decomposition tank;
A hydrogen peroxide supply device for supplying the hydrogen peroxide to the decomposition tank;
An ozone supply device for supplying the ozone to the decomposition tank;
A separator for separating the spent ion-exchange resin from which the radionuclide or heavy metal element is desorbed and the waste containing the radionuclide or heavy metal element;
A treatment apparatus for used ion exchange resin, comprising a volume reduction device for reducing the volume of waste.

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