JPH10279726A - Volume reduction of waste ion-exchange resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the process that can reduce the volume of waste ion- exchange resin as much as possible. SOLUTION: This is a process that a resin mixture of cationic ion-exchange resin and anionic ion-exchange resin is reduced in its volume before its disposal. In this process, the cationic ion exchange resin and the anionic ion-exchange resin are separated from each other, the separated anionic ion-exchange resin is supercritically hydroxylated by reaction with an oxidizing agent free from any substance to form salt in the presence of supercritical water, while the separated cationic ion-exchange resin is supercritically hydroxylated by reaction with an oxidizing agent free from any substance to form salt in the presence of supercritical water and the acids formed are neutralized with an alkali agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for separating harmful substances.
Regarding the technology for reducing the volume of the ion-exchange resin used for removal when disposing of the waste, more specifically, supercritical water oxidation (SCW)
The present invention proposes a method suitable for volume reduction by the O) method.

[0002]

2. Description of the Related Art Conventionally, when a harmful substance (hazardous metal, radioactive substance, etc.) is contained in a fluid such as water, separation and removal with an ion exchange resin has been performed. In the condensate system of a nuclear power plant, radioactive substances are contained in cladding and the like that are adsorbed and adhered when condensed water is treated by a condensate desalination device or the like. It is necessary to properly dispose of ion-exchange resins that have adsorbed and attached these harmful substances.For example, ion-exchange resins that have adsorbed radioactive substances are generally sealed in drums using cement or asphalt, etc. There is a method of storing and managing as a solid in a storage facility.

However, this method has a problem that, since a solidifying agent such as cement is used, the volume of the ion exchange resin is unavoidably increased as compared with the original volume.

[0004]

As a solution to the above problem, reducing the volume of the ion exchange resin itself to which harmful substances are adsorbed and adhered leads to a reduction in the amount of the solidifying agent at the same time. Therefore, it is considered to be an effective method.

[0005] However, ion exchange resins are generally hardly decomposable substances, and there are restrictions on the technology used as a technique for reducing the volume of ion exchange resins. In addition, the substances to be treated in the present invention adsorb harmful substances.・ Because of the restriction that they adhere, no suitable method has been proposed in the past.

[0006] For example, direct combustion method, known as physical-chemical treatment method for decomposing a hardly decomposable substance, etc. wet oxidation method, in the former, the NO _X, SO _X although complete decomposition of the ion exchange resin can be In addition to the emission, there is a problem that it is necessary to take measures to prevent harmful substances from being included in the waste gas when releasing the combustion gas to the atmosphere. There is a limit to the decomposition of ion exchange resins.

[0007] In addition to the above, as a decomposition treatment technique for a hardly decomposable substance, a supercritical hydroxylation treatment technique for treating a hardly decomposable substance containing a chlorine compound, a nitrogen compound, a sulfur compound, or the like has attracted attention (for example, Japanese Patent Publication No. H10-26103). 1-38532).

The method using supercritical water oxidation is basically carried out in the apparatus shown in FIG. That is, the fluid containing the decomposition target is supplied from the decomposition target storage tank 200 through the fluid supply pipe 201 to the reaction vessel 20.
2 and an oxidant fluid such as oxygen and supercritical water are supplied and mixed from respective supply pipes 203 and 204 on the way. Thus, the decomposition target is oxidatively decomposed under the supercritical condition of water in the reaction vessel. The generated fluid (decomposition product), which has become water and gas (mainly carbon dioxide gas and some volatile substances) generated by this reaction, is cooled, and the gas decompressed by the decompression mechanism 205 is discharged to the atmosphere through an exhaust pipe 206. Then, the water removes the inorganic substances and the like contained in the water as necessary to remove the condensed water drain pipe 207.
Discharge through. When the decomposition target contains a substance that generates an acid, an alkali is added (injected) from the alkali supply pipe 208 to neutralize the acid, and the salt generated by the neutralization is converted into
Supply pipe 209 is connected to the bottom of vessel type reaction vessel 202.
And then dissolved in the salt transfer water discharged through the discharge pipe 210 and discharged.

According to this method, the polarity of water (supercritical water) under the critical conditions of water, that is, the temperature exceeding the critical temperature of 374 ° C. and the critical pressure of 22 MPa, can be controlled by the temperature and the pressure, and the paraffin-type carbonized water can be obtained. It can also dissolve non-polar substances such as hydrogen and benzene, and can be mixed with oxygen and other gases in a single phase at an arbitrary ratio. If the carbon content of the product is several percent, it can be heated to a critical temperature or higher only by the heat of oxidation, so it is extremely excellent in thermal energy, and supercritical organic and harmful organic wastes are almost supercritical. It can be completely decomposed by properly controlling the hydrolysis reaction and thermal decomposition reaction in water, and in particular, it can be processed in a closed system. It is.

[0010] However, in the case of an ion-exchange resin to which a substance that cannot be released to the outside such as a radioactive substance or a harmful metal is adsorbed and adhered, the amount of the generated salt becomes a problem. That is, since the reaction solution containing the radioactive substance or the like must be concentrated and stored, etc., if the amount of the inorganic salt contained in the solution is large, the subsequent concentration and volume reduction cannot be performed sufficiently. Therefore, it is desired that the amount of the neutralizing agent added be as close to the equivalent as possible with respect to the generated acid.

An object of the present invention is to provide a method capable of realizing an optimum treatment by using a supercritical water oxidation treatment when reducing the volume of the used waste ion exchange resin. It is a thing.

Further, in the present invention, in the supercritical water oxidation treatment method adopted for the above treatment, the amount of a neutralizing agent added for neutralizing the generated acid can be reduced as much as possible, so that the amount of waste is reduced as much as possible. The aim is to provide a method that can.

Another object of the present invention is to make it possible to carry out the supercritical water oxidation treatment for reducing the volume of the waste ion exchange resin by the operation as simple as possible.

[0014]

The above object is achieved by the invention described in each claim of the present application.

The invention of the method for reducing the volume of a waste ion exchange resin according to claim 1 is a method for reducing the volume of a mixed ion exchange resin containing a cation exchange resin and an anion exchange resin before disposal. The ion exchange resin from which at least the cation exchange resin has been removed, in the presence of supercritical water,
It is characterized in that supercritical water oxidation is performed by reaction with an oxidizing agent that does not contain a salt-forming substance.

In the above, "removing the cation exchange resin"
This means that the cation exchange resin is contained as little as possible. In other words, the cationic resin generally contains sulfur and generates sulfuric acid with supercritical water oxidation, so neutralization with an alkali is required, but the anion exchange resin is used exhausted from the condensate desalination unit. When the ionic form is the OH type (regeneration type) as described above, a substance that generates an acid is not contained, so that neutralization with an alkali is not necessary. For this reason, supercritical water oxidation can be performed on the remaining ion-exchange resin from which the cation-exchange resin has been removed without performing the neutralization treatment. Such cation exchange resin is removed, for example, when a mixed ion exchange resin containing both resins is back-washed and settled to separate (so-called specific gravity difference separation), a portion where both resins are mixed near the separation surface. It can be performed by an operation of removing the upper anion exchange resin.
Therefore, in the specific gravity difference separation, it means that the mixed region of both resins and the cation exchange resin region are removed.

The term "oxidizing agent not containing a salt-forming substance" refers to an inorganic salt (KCl, NaCl, etc.) associated with decomposition.
Means that an oxidizing agent that does not generate any gas, such as oxygen gas, air, etc., is used as the oxidizing agent. The reason for using such an oxidizing agent is that if a solid oxygen-containing compound such as KClO ₄ or NaClO ₂ is used as the oxidizing agent, a large amount of the above-mentioned inorganic salt is generated, and these salts are contained in the harmful substances. This is because it becomes waste and the volume reduction of the waste becomes insufficient.

According to the present invention, the volume of an anion exchange resin containing no substance that generates an acid can be reduced by supercritical water oxidation without requiring the addition of an alkali.

A second aspect of the present invention is a method for reducing the volume of a mixed ion-exchange resin containing a cation-exchange resin and an anion-exchange resin prior to disposal. The ion-exchange resin from which at least the anion-exchange resin has been removed is supercritically hydroxylated by reaction with an oxidizing agent containing no salt-forming substance in the presence of supercritical water, and the generated acid is neutralized with an alkali agent. It is characterized by summing.

In the above, "removing the anion exchange resin"
This means that the anion exchange resin should be mixed as little as possible. However, unlike the cation exchange resin removal treatment in the invention of claim 1, it is necessary to strictly exclude the anion exchange resin from being mixed. It does not do. That is, the commonly used Amberlite
Since a strong acidic cation exchange resin such as (registered trademark) 200C contains a substance that generates an acid, it generates an acid in a supercritical water oxidation treatment, and therefore requires a neutralization treatment by addition of an alkali. In this case, there is basically no problem even if an anion exchange resin that does not require a neutralization treatment is mixed. However, when the mixing amount of the anion exchange resin is unknown, it is necessary to add an alkali in an amount calculated as a cation exchange resin for all of its capacity, and therefore, useless alkali is added. For these reasons, it is desirable to minimize the mixing of the anion exchange resin. The resin in the region where both resins are mixed can be treated by this method. Therefore, in the specific gravity difference separation,
It means that only the anion exchange resin region except the mixed region of both resins is removed.

In the above, examples of the alkali agent for neutralizing the acid include sodium hydroxide, potassium hydroxide, calcium hydroxide, potassium carbonate, calcium carbonate and the like.

According to the present invention, the volume of a cation exchange resin containing a substance that produces a salt can be reduced by supercritical water oxidation efficiently.

A third aspect of the present invention is a method of reducing the volume of a waste ion exchange resin before disposing the ion exchange resin in a mixed state of a cation exchange resin and an anion exchange resin. The separation resin and the anion exchange resin are separated, and the separated anion exchange resin is supercritically hydroxylated by reaction with an oxidizing agent that does not contain a substance that forms a salt in the presence of supercritical water, and the separated cation exchange resin is It is characterized in that supercritical water is supercritically hydroxylated by a reaction with an oxidizing agent containing no substance that forms a salt in the presence of supercritical water, and the generated acid is neutralized with an alkali agent.

In the above configuration, the separation of the two resins is performed in the same manner as described in the first and second aspects, and the mixed portion of the two resins is separated so as to be combined with the cation exchange resin.

According to the present invention, the supercritical hydroxylation treatment of the anion exchange resin and the cation exchange resin can be performed in separate apparatuses, or can be performed by changing the processing procedure using the same apparatus. According to the latter, supercritical water oxidation treatment equipment can be shared, which is advantageous in equipment cost.

A fourth aspect of the present invention is a method for reducing the volume of a waste ion exchange resin before disposing the ion exchange resin in a mixed state of a cation exchange resin and an anion exchange resin. After separating the anion exchange resin and the anion exchange resin, they are mixed uniformly and supplied to the reaction zone where the supercritical water is used to react with an oxidizing agent that does not contain a salt-forming substance to supercritically hydroxylate. And neutralizing the generated acid with an alkali agent.

According to the present invention, since the ion exchange resin is separated and then uniformly mixed and supplied to the reaction zone, the cation exchange resin is not unevenly distributed in the supply fluid but exists at an average concentration. Further, the addition of an alkali agent for neutralizing the generated acid can be supplied in a fixed amount, thereby simplifying the operation.

The "separation" in the above configuration is the same as in the first and second aspects, and the "uniform mixing" refers to averaging the concentration of the cation exchange resin.
The method of uniform mixing may be such that the mixture is supplied to the reaction area after being uniformly mixed in a mixing tank or the like, or the amount of the separated anion exchange resin storage tank and the cation exchange resin storage tank is controlled, and A uniform mixture may be supplied to the reaction zone via a line mixer or the like. The uniform ratio may be an appropriate ratio such as 1: 2, 2: 1 or the like in addition to the case where both resins are 1: 1.

A fifth aspect of the present invention is characterized in that, in the fourth aspect of the present invention, the homogeneously mixed ion exchange resin is continuously supplied at a constant supply rate to the reaction zone of supercritical water oxidation.

In the above description, "constant supply amount" means to make the supply amount per unit time constant. However, the present invention is not limited to this, and the addition amount of the alkali agent may be variably controlled according to the change in the supply amount of the resin.

According to the present invention, the control of the addition of an alkali agent for neutralization is further facilitated.

According to a sixth aspect of the present invention, in each of the above-mentioned inventions, the ion exchange resin is pulverized.

According to the present invention, by reducing the particle size of the ion exchange resin, the operation of supplying the fluid in the slurry state to the reaction zone can be performed more smoothly.

According to a seventh aspect of the present invention, in each of the above-mentioned inventions, the ion exchange resin to be disposed of is an ion exchange resin used in a nuclear power plant.

According to the present invention, the volume of the ion exchange resin which is radioactive waste can be significantly reduced.

The invention of the apparatus for reducing the volume of waste ion exchange resin according to claim 8 is a separation apparatus for separating a cation exchange resin and an anion exchange resin in a mixed state, and a method for uniformly separating both ion exchange resins at a predetermined ratio. A mixing device for mixing, and the resulting homogeneously mixed ion exchange resin is supercritically hydroxylated by reacting the homogeneously mixed ion exchange resin with an oxidizing agent not containing a substance that forms a salt in the presence of supercritical water. A supercritical water oxidation apparatus and a continuous supply apparatus of a fluid to be decomposed, which continuously supplies the homogeneous mixed ion exchange resin in a constant amount to the supercritical water oxidation apparatus.

As the “separation device” in the above configuration,
For example, there can be mentioned a device for performing a specific gravity difference separation by backwashing and settling. The "predetermined ratio" means, for example, that the ratio of the cation exchange resin to the anion exchange resin is 1: 1 or the like. Generally, the ratio is the ratio of the mixing ratio when used as the mixed ion exchange resin. Is often better.

As the “mixing device” in the above configuration,
Examples thereof include a mixing tank having stirring blades and the like for mixing in advance, and an apparatus for mixing a line mixer or the like while sending both resins by a predetermined amount from an anion exchange resin storage tank and a cation exchange resin storage tank.

According to the present invention, the supply fluid in which the cation exchange resin is mixed at an average concentration without uneven distribution can be supplied to the reaction zone. For example, the addition of an alkali agent for neutralizing the generated acid can be kept constant. A simple operation that can be supplied in a quantity can be performed.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail based on embodiments shown in the drawings.

Embodiment 1 FIG. 1 shows an apparatus used for carrying out a method for separating a used mixed ion exchange resin discharged from a condensate desalination apparatus into a cation exchange resin and an anion exchange resin and performing a supercritical water oxidation treatment. This is an outline of the above.

In FIG. 1, reference numeral 1 denotes a treated (decomposed) resin storage tank for receiving a used mixed ion-exchange resin in a condensate system of a nuclear power plant, for example. It is provided so that the resin can be transferred by a feed pump (not shown).

Separated water is supplied from the lower part of the tank 31 of the separation apparatus through the separation water supply pipe 32 and the separated water discharge pipe 33 of the upper part of the tank 31 is transferred to the separation apparatus 3.
An operation is performed to generate an upward flow in the tank 31 by discharging the resin, and to separate the resin using the specific gravity difference between the cation exchange resin and the anion exchange resin. And after stopping the water flow after the separation water flow for a certain period of time and allowing it to settle,
In the tank 31 of the separation device 3, a resin having a low specific gravity (anion exchange resin layer: A) and a resin having a high specific gravity (cateon exchange resin layer K) are separated in an upper layer portion, and both resins are located in an intermediate position. Are separated from each other in the mixed layer M.

Separated upper layer of anion exchange resin A
Is transferred to and stored in the anion exchange resin storage tank 4 via the anion resin transfer pipe 34, and in this example, the resin in the middle mixed layer M is transferred to the resin storage tank 1 via the return pipe 35.
The remaining cation exchange resin K is transferred to the cation exchange resin storage tank 5 via the transfer pipe 36 and stored therein. 21,331,321,331,341,35
Reference numerals 1 and 361 denote on-off switching valves which are opened when necessary.

In this example, the resin of the intermediate mixed layer M is returned to the resin storage tank 1 to be treated. However, the resin of the mixed layer M and the resin of the cation exchange resin layer K are combined together in the cation exchange resin storage tank. 5 may be transferred.

The structure of the separator 3 and the operation of separation described above are based on, for example, a highly reliable system conventionally used in an ion-exchange resin regeneration unit of a condensate and desalination unit of a power plant. Can be configured.

Each of the cation exchange resin and the anion exchange resin separated as described above,
Alternatively, the resin supply pipe 7 to be treated is uniformly mixed at a certain ratio.
Is supplied to the reaction vessel 8 of the supercritical water oxidation apparatus through the above, and the supercritical water oxidation treatment is performed. Hereinafter, the supercritical water oxidation treatment performed on the separated ion exchange resin will be described by dividing into several patterns.

(1) Supercritical Water Treatment of Anion Exchange Resin Alone In this example, an anion exchange resin (cation exchange resin) having a particle size of generally about 0.3 to 0.5 mm stored in an anion exchange resin storage tank 4 is used. Is suspended in a predetermined amount of water to form a slurry, and is supplied from a supply pipe 41 and an on-off valve 42 to a reaction vessel 8 for performing a supercritical water oxidation reaction via a resin supply pipe 7 to be treated. The resin may be pulverized into finer particles before or after storage in the tank 4 using a device for pulverizing and crushing the same (the same applies to the cation exchange resin).

In the supercritical water oxidation reaction of this example, since the resin to be treated is an OH-type anion exchange resin, no inorganic acid is generated even if it is decomposed, so that injection of an alkali agent for acid neutralization is not required. . Also, even if the anion exchange resin adsorbs salts such as chloride ions and generates an acid with the decomposition treatment, the anion exchange resin used in the condensate system is of the chloride ion type. Since the salt type is usually extremely small, the amount of generated acid is also small, so that injection of an alkali agent for acid neutralization is substantially unnecessary.
If the amount of adsorbed chloride ions of the anion exchange resin is abnormally large due to, for example, a special situation at the time of use (seawater leak or the like), an appropriate amount of neutralizing alkali agent may be used in the same manner as described in (2) below, if necessary. May be added.

In this embodiment, an oxidizing agent required for the oxidation reaction is supplied from an oxidizing agent supply pipe 81. As described above, it is essential that the oxidizing agent used in this case does not include a substance that generates a salt, and for example, air, oxygen gas, and the like are preferable.

In the present embodiment, the resin fluid to be treated and the oxidizing agent are previously mixed in the middle of the resin supply pipe 7 to be treated. However, the present invention is not limited to this. May be supplied to the reaction vessel 8. In this example, the supercritical water as the reaction solvent is described as an example obtained by heating the water in which the resin is suspended to a temperature higher than the supercritical temperature. Appropriate necessary heating means and high-pressure means (both not shown), which can be constituted by using, are provided, but are not limited thereto, and separately prepared supercritical water is supplied to the reaction vessel 8 or the resin supply pipe 7 to be treated.
May be introduced. 42, 52, 71, 10
Reference numerals 1,111, 811 and 821 denote on-off switching valves which are opened when necessary.

The reaction vessel 8 of this embodiment has a vertical cylinder type vessel structure called a vessel type, and contains a resin to be treated, an oxidizing agent, and supercritical water from the upper center of the reaction vessel 8 through a nozzle. The fluid is continuously blown, causing a supercritical water oxidation reaction in the vessel, and the oxidatively decomposed fluid (water, gas)
Is discharged out of the reaction vessel 8 through the discharge pipe 9 connected to the upper side.

As described above, the anion exchange resin, which is the resin to be treated (substance to be decomposed), supplied to the reaction vessel 8 is oxidatively decomposed in the presence of supercritical water and decomposed into water and gas. The cooled fluid is decompressed by the decompression mechanism 91 after being cooled in the middle of the discharge pipe 9, separated into condensed water and gas, the gas is discharged out of the system through the exhaust pipe 10, and the condensed water is discharged through the condensed water discharge pipe 11 through the system. It is discharged outside.

In the supercritical water oxidation treatment of this example, an anion exchange resin containing no acid-generating substance can be oxidatively decomposed by a simple operation control without adding a neutralizing agent.

(2) Supercritical water oxidation treatment of cation exchange resin alone In this example, the cation exchange resin stored in the cation exchange resin storage tank 5 is treated with a predetermined amount of water in the same manner as in the above example (1). Suspended and made into slurry, supply pipe 51, on-off valve 52
The case where the supercritical water oxidation treatment is performed by supplying the reaction vessel 8 to the reaction vessel 8 through the resin supply pipe 7 to be treated will be described.

In the case of this example, the resin to be treated is a cation exchange resin (for example, Amberlite 200C (described above)) containing a substance that generates an inorganic acid by a decomposition reaction.
This is different from the above (1) in that an alkali agent is supplied from an alkali supply pipe 82 to neutralize sulfuric acid generated by decomposition in order to prevent corrosion in the reaction vessel 8 and the subsequent pipes and the like. In addition, the configuration and operation required for the device to be used are different from the above example (1) in accordance with this difference. The other points except for this are the same as the above-mentioned example (1).

The difference between the above example (1) and the configuration and operation required for the apparatus will be described below.
The operation of supplying water below the supercritical temperature, which is salt transfer water, from the salt transfer water supply pipe 83 and discharging it from the salt discharge pipe 84 to the bottom of the vessel-type reaction vessel 8 used in the above step is performed. The configuration is adopted.
That is, these constitutions are to supply the inorganic salt precipitated in the reaction vessel 8 to the reaction vessel 8 by neutralizing the inorganic acid generated in this example (2) in which the cation exchange resin is supercritically hydroxylated. It is dissolved in water below the critical temperature (functionally water for transporting salt) and discharged. According to the configuration of the present example, the inorganic salt having a large specific gravity generated by the supercritical water oxidation reaction in the vessel-type reaction vessel 8 falls from the apparatus structure into the salt transfer water below the reaction vessel 8 and is dissolved. As a result, apart from the pipeline for sending the generated fluid (water, gas) from the reaction vessel 8 to the subsequent stage, highly adherent salts which are likely to block the pipeline can be separated and removed from the system. In addition, continuous decomposition treatment of the cation exchange resin can be achieved.

The addition position of the alkali agent for neutralizing the acid generated in the supercritical hydroxylation reaction is not necessarily limited to the starting end side where the resin to be treated is supplied to the reaction vessel 8. Any position may be used as long as it can prevent acid corrosion of the reaction vessel 8 or the subsequent piping.

(3) Supercritical water oxidation treatment in which anion exchange resin and cation exchange resin are uniformly mixed In this case, the cation exchange resin and the anion exchange resin are uniformly mixed at a fixed ratio. The water is supplied to the supercritical water oxidation apparatus 3 via the resin supply pipe 7 while being treated.

In this example, as in the above example (2),
Since the resin to be treated (a mixture of an anion exchange resin and a cation exchange resin) contains an organic substance that decomposes to generate an inorganic acid, an alkali agent for acid neutralization is supplied from the alkali agent supply pipe 82 to prevent corrosion of the reaction vessel. Supply. The configuration and operation required for the other devices are the same as in (2) above.

Since the amount of the anion exchange resin mixed in the cation exchange resin is known, the amount of the alkali as a neutralizing agent may be added in accordance with the cation exchange resin. Disappears.

According to the first embodiment described in the above (1) to (3), the anion exchange resin and the cation exchange resin are each made independent by supercritical water oxidation treatment suitable for each, so that the nuclear power plant The volume of the ion exchange resin generated as a result of the use can be appropriately reduced, which is extremely useful in treating a substance containing a radioactive substance.

In this example, the case where a vessel type reaction vessel is used as the supercritical water oxidation treatment apparatus has been described. However, the treatment method of the present invention is not limited to the type of the reaction vessel, and may be, for example, a pipe type. It can also be applied to supercritical water oxidation using a so-called reaction vessel.

Embodiment 2 In the present embodiment shown in FIG. 2, when the ion exchange resin containing the cation exchange resin is subjected to the supercritical water oxidation treatment in the above Embodiment 1 (the above (2) and (3)), This shows an example suitable for further reducing and suppressing the generation amount.

For example, when the waste ion exchange resin is a mixture of regenerated and salt type cation exchange resins and anion exchange resins, the state of the mixture is accurately grasped, and an alkali as a neutralizing agent is added in advance. It is difficult. In this case, it is generally necessary to add a large amount of the neutralizing agent because it is necessary to avoid a risk that the durability of the device may be deteriorated by acid due to insufficient neutralization, or that the discharge pipe may be blocked. However, unlike the oxidative decomposition treatment of general flame-retardant organic substances, in the treatment of ion-exchange resin to which radioactive substances and harmful metals targeted by the present invention are adsorbed and adhered, the neutralizing agent is simply used. Increasing the amount of addition has another problem that detracts from the purpose of reducing the volume of waste.

Therefore, in the present embodiment, a pH meter 842 is installed in the line of the salt transfer water discharge pipe 84 of the supercritical water oxidation apparatus, and the pH of the salt transfer water is measured. The addition amount is controlled by feeding back to the drive control of the injection pump 822.
Other configurations are the same as those in FIG.

Thus, even if the amount of the alkaline agent required for acid neutralization changes, the amount of addition can be changed to follow the change, thereby suppressing the amount of salt generated.

[0068]

As described above, according to the inventions of the present application, it is possible to reduce the volume of a used waste ion exchange resin to which a radioactive substance or a harmful metal is adsorbed and adhered while minimizing salt formation. Thus, there is an effect that the amount of waste finally solidified and stored can be reduced.

According to the fourth and fifth aspects of the present invention,
Since the amount of the neutralizing agent to be added for neutralizing the acid generated by the supercritical water oxidation treatment can be added in a constant amount, the operation is simplified.

[Brief description of the drawings]

FIG. 1 is a flow chart showing an outline of a configuration of a volume reduction device according to a first embodiment of a waste ion exchange resin used for carrying out the method invention of the present application.

FIG. 2 is a flow chart showing a part of a configuration outline of a volume reduction device according to a second embodiment of the waste ion exchange resin used to carry out the method invention of the present application.

FIG. 3 is a flowchart showing an outline of the configuration of a conventional supercritical water oxidation apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Resin tank to be processed 2 ... Transfer pipe 21 ... Open / close switching valve 3 ... Separator 31 ... Tank 32 ... Separated water supply pipe 321 ... Open / close switching valve 33 ... Separated water discharge pipe 331 Open / close switching valve 34 Anion exchange resin transfer pipe 341 Open / close switching valve 35 Return pipe 351 Open / close switching valve 36 Cation exchange resin transfer pipe 361: Open / close switching valve 4 ... Anion exchange resin storage tank 41 ... Supply pipe 42 ... Open / close switching valve 5 ... Cation exchange resin storage tank 51 ... Supply pipe 52 ... Open / close switching Valve 7: Resin to be treated supply pipe 71: Open / close switching valve 8: Reaction vessel (supercritical water oxidation device) 81: Oxidant supply pipe 811: Open / close switching valve 82: Alkaline Supply pipe 821: open / close switching valve 822: pump 3 ... Salt transfer water supply pipe 831 ... Open / close switching valve 84 ... Salt transfer water discharge pipe 841 ... Open / close switching valve 842 ... pH meter 9 ... Drain pipe 10 ... Exhaust pipe 101: open / close switching valve 11: condensed water discharge pipe 111: open / close switching valve

Claims (8)

[Claims] 1. A method for reducing the volume of a mixed ion-exchange resin containing a cation-exchange resin and an anion-exchange resin before disposal, wherein the ion-exchange resin from which at least the cation-exchange resin is removed is supercritical A method for reducing the volume of a waste ion exchange resin, wherein supercritical water oxidation is carried out in the presence of water by reaction with an oxidizing agent which does not contain a salt-forming substance. 2. A method for reducing the volume of an ion-exchange resin in a mixed state containing a cation-exchange resin and an anion-exchange resin before disposal, wherein the ion-exchange resin from which at least the anion-exchange resin has been removed is supercritical. Supercritical water oxidation by reaction with an oxidizing agent that does not contain a salt-forming substance in the presence of water, and neutralizing the generated acid with an alkali agent reduces the volume of waste ion exchange resin. Method. 3. A method for reducing the volume of an ion-exchange resin in a mixed state of a cation-exchange resin and an anion-exchange resin before discarding the same, wherein the cation-exchange resin and the anion-exchange resin are separated, and the separated anion-exchange resin is separated. Is supercritically hydroxylated by reaction with an oxidizing agent that does not contain a substance that produces a salt in the presence of supercritical water, and the separated cation exchange resin contains a substance that produces a salt in the presence of supercritical water. A method for reducing the volume of a waste ion exchange resin, comprising supercritically hydroxylating by reaction with a non-oxidizing agent and neutralizing the generated acid with an alkali agent. 4. A method for reducing the volume of an ion-exchange resin in a mixed state of a cation-exchange resin and an anion-exchange resin before discarding, wherein the cation-exchange resin and the anion-exchange resin are separated and then uniformly mixed. In the presence of supercritical water, the reaction with an oxidizing agent not containing a salt-forming substance is supplied to a reaction zone for supercritical water oxidation, and the generated acid is neutralized with an alkali agent. How to reduce the volume of waste ion exchange resin. 5. The method for reducing the volume of a waste ion-exchange resin according to claim 4, wherein the homogeneously mixed ion-exchange resin is continuously supplied in a constant supply amount to a reaction zone for supercritical water oxidation. 6. The method according to claim 1, wherein
A method for reducing the volume of waste ion-exchange resin, which comprises crushing the ion-exchange resin. 7. The method according to claim 1, wherein
A method for reducing the volume of a waste ion exchange resin, wherein the ion exchange resin to be disposed of is an ion exchange resin used in a nuclear power plant. 8. A separation device for separating a cation exchange resin and an anion exchange resin in a mixed state, a mixing device for uniformly mixing both separated ion exchange resins at a predetermined ratio, and a uniform ion exchange resin obtained. A supercritical water oxidation device that supercritically waters the homogeneously mixed ion exchange resin by reacting with an oxidizing agent that does not contain a substance that produces a salt in the presence of supercritical water; and A continuous supply device for a fluid to be decomposed, which continuously supplies a fixed amount of a mixed ion exchange resin, and a volume reduction device for a waste ion exchange resin.