WO2015060250A1 - 鉄族金属イオン含有液の処理方法及び処理装置、CoとFeの電着方法及び装置、並びに放射性廃イオン交換樹脂の除染方法および除染装置 - Google Patents
鉄族金属イオン含有液の処理方法及び処理装置、CoとFeの電着方法及び装置、並びに放射性廃イオン交換樹脂の除染方法および除染装置 Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
- C25C1/06—Electrolytic production, recovery or refining of metals by electrolysis of solutions or iron group metals, refractory metals or manganese
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
- G21F9/04—Treating liquids
- G21F9/06—Processing
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
- G21F9/04—Treating liquids
- G21F9/06—Processing
- G21F9/12—Processing by absorption; by adsorption; by ion-exchange
Definitions
- the first invention relates to a method and apparatus for treating an iron group metal ion-containing liquid, and more specifically, from a liquid containing iron group metal ions such as iron (Fe), cobalt (Co), and nickel (Ni).
- the present invention relates to a method and an apparatus for removing water.
- the first invention particularly relates to iron group metals generated from nuclear power plants such as decontamination waste liquid generated in nuclear power plants and eluents obtained by eluting iron group metal ions from ion exchange resins used in nuclear power plants. It is suitably used for the treatment of waste liquid containing ions.
- the second invention relates to a method and apparatus for electrodeposition of Co and Fe, and more particularly to a method and apparatus for simultaneously removing these ions from a liquid containing Co ions and Fe ions by electrodeposition.
- the second invention relates to Co ions and Fe generated from nuclear power plants, such as decontamination waste liquid generated in nuclear power plants, and waste liquid eluting radioactive materials adsorbed on ion exchange resins used in nuclear power plants. It is suitably used for the treatment of waste liquid containing ions.
- the third invention is a decontamination method for efficiently removing radioactive material from waste ion exchange resin containing a cladding mainly composed of iron oxide while adsorbing radioactive material used in nuclear power plants and the like.
- the present invention relates to a decontamination apparatus.
- decontamination waste liquid is generated when radioactive substances are chemically removed from the primary cooling system equipment and piping contaminated with radioactive substances, and from the metal member surfaces of the systems including these.
- These decontamination waste liquids contain iron group metal ions such as Fe, Co or Ni, and also contain a large amount of radioactive substances such as Co-60 (cobalt 60) and Ni-63 (nickel 63).
- the decontamination waste liquid is reused as a decontamination liquid after the ionic components dissolved by the ion exchange resin are removed. For this reason, there exists a problem that the waste of the ion exchange resin containing many radioactive substances generate
- the ion exchange resin used to purify the cooling water system containing radioactive materials by directly touching the fuel rods such as the reactor water purification system (CUW) and the fuel storage pool water purification system (FPC) Therefore, it is stored as a high dose rate waste in a resin tank installed in the power plant. Waste containing these radioactive substances is finally kneaded with a solidification aid such as cement and stabilized, and then buried.
- a solidification aid such as cement and stabilized, and then buried.
- the cost for disposal is different depending on the amount of radioactive material contained, and the higher the concentration of radioactive material, the higher the cost. For this reason, it is economical to reduce the volume of waste with a high dose rate as much as possible and then use it as a solid waste.
- the radioactive substance can be separated from the ion exchange resin as a solid and can be contained in a shielding container.
- Waste ion exchange resin from which radioactive materials have been removed is a low-dose rate waste with low disposal costs, and if the radioactive materials can be removed to a level where incineration of the waste ion exchange resin can be achieved, incineration will significantly Volume reduction can be achieved.
- Patent Document 3 discloses a technique in which sulfuric acid is passed through waste resin, ionic radioactive substances are eluted, radioactive substances are separated from the eluent by diffusion dialysis, and sulfuric acid is circulated and reused.
- Patent Document 4 discloses a waste resin treatment method in which waste resin is immersed in an oxalic acid aqueous solution to dissolve the metal clad on the surface and metal ions adsorbed on the resin are eluted into the oxalic acid aqueous solution. In these cases as well, waste liquid containing radioactive substances is generated, but the solidification process is not covered.
- Patent Document 5 discloses that a decontamination solution in which radioactive cations are dissolved is energized while passing through an electrodeposition cell, and the radioactive cations are converted into radioactive metals.
- a technique for regenerating and reusing a decontamination solution by depositing it on a cathode as particles is disclosed. At that time, the cathode on which radioactive metal particles are deposited is described as pouring catholyte over the entire cathode to desorb the radioactive metal particles.
- Patent Document 5 a decontamination solution in which radioactive cations are dissolved is energized while being directly introduced into the cathode side of the electrodeposition cell, and radioactive cations are deposited on the cathode as radioactive metal particles.
- the catholyte property changes depending on the decontamination solution, the catholyte cannot be adjusted to a liquid property suitable for electrodeposition.
- the decontamination solution is an acidic waste solution
- the radioactive metal component deposited on the cathode surface is dissolved again in the acidic waste solution, so that no precipitation occurs or the deposition rate is significantly reduced.
- the ion exchange resin used to purify the cooling water system containing radioactive materials by directly touching the fuel rods such as the reactor water purification system (CUW) and the fuel storage pool water purification system (FPC) Because it is adsorbed in large quantities, it is stored in a resin tank inside the power plant as radioactive waste with a high dose rate.
- ion-exchange resins are used to remove radioactive substances from primary cooling system equipment and piping contaminated with radioactive substances and the surface of metal parts including these by chemical cleaning.
- Spent ion exchange resin is also stored in the resin tank as high dose rate radioactive waste. Waste containing these radioactive substances is finally kneaded with a solidification aid such as cement and stabilized, and then buried.
- the cost for disposal is different depending on the amount of radioactive material contained, and the higher the concentration of radioactive material, the higher the cost. For this reason, it is economical to reduce the volume of waste with a high dose rate as much as possible and then use it as a solid waste. Specifically, it is desirable in terms of volume reduction if the radioactive substance can be separated from the ion exchange resin as a solid and can be contained in a shielding container. Waste ion exchange resin from which radioactive materials have been removed is a low-dose rate waste with low disposal costs, and if the radioactive materials can be removed to a level where incineration of the waste ion exchange resin can be achieved, incineration will significantly Volume reduction can be achieved.
- the volume of radioactive waste can be significantly reduced.
- the radioactive ash is concentrated in the incinerated ash, resulting in a high dose of incinerated ash. If the radioactive material can be completely removed from the waste resin, the incineration ash can be prevented from becoming a high dose, and the volume can be reduced by incineration. Therefore, various technologies for removing the radioactive material from the waste resin have been studied. Yes.
- the high-dose waste resin used in the reactor water purification system and the fuel storage pool water purification system adsorbs radioactive material ions and is mixed with cladding containing iron oxide as the main component. Since the clad also contains a radioactive substance, it is necessary to remove the clad from the waste resin at the same time in order to completely remove the radioactive substance from the waste resin.
- the chemical form of the clad contained in the waste resin mainly includes magnetite (Fe 3 O 4 ) and hematite ( ⁇ -Fe 2 O 3 ).
- Patent Document 6 discloses that sulfuric acid is passed through an eluent filled with waste resin, ionized radioactive substances are eluted, and radioactive substances are separated from the eluent by diffusion dialysis.
- a technique for recycling and recycling sulfuric acid is disclosed. As described above, in the method in which unwarmed sulfuric acid at room temperature is passed through the waste resin, it is difficult to dissolve the hardly soluble hematite ( ⁇ -Fe 2 O 3 ), and the clad is removed from the waste resin. The problem is that radioactive materials remain because they cannot.
- iron that efficiently deposits and removes iron group metal ions from the liquid without being affected by the liquid properties of the iron group metal ion-containing liquid It is an object of the present invention to provide a processing method and a processing apparatus for a Group metal ion-containing liquid.
- the second invention is an electrodeposition for efficiently removing Co and Fe from the liquid by making the liquid property suitable for the electrodeposition of Co and Fe in the electrodeposition treatment of the liquid containing Co ions and Fe ions. It is an object to provide a method and an apparatus.
- 3rd invention is the decontamination method and decontamination apparatus which reduce the dose of waste ion exchange resin to a very low level by removing the radioactive radioactive substance in waste ion exchange resin, and melt
- the inventors have introduced an iron group metal ion-containing liquid into an anode chamber of an electrodeposition tank in which an anode chamber having an anode and a cathode chamber having a cathode are separated by a cation exchange membrane, and the catholyte is introduced into the cathode chamber.
- the gist of the first invention is as follows.
- An anode chamber having an anode and a cathode chamber having a cathode are separated by a cation exchange membrane, an iron group metal ion-containing liquid is introduced into the anode chamber, a catholyte is introduced into the cathode chamber, By energizing between the anode and the cathode, the iron group metal ions in the liquid in the anode chamber permeate through the cation exchange membrane and move into the liquid in the cathode chamber, and the iron group metal is placed on the cathode.
- Electrodeposition tank having an anode chamber with an anode, a cathode chamber with a cathode, a cation exchange membrane separating the anode chamber and the cathode chamber, and energization means for energizing between the anode and the cathode And a liquid passing means for passing the iron group metal ion-containing liquid into the anode chamber, and a liquid passing means for passing the catholyte through the cathode chamber, and by energizing between the anode and the cathode.
- the anode chamber for introducing the iron group metal ion-containing liquid and the cathode chamber for depositing the iron group metal are separated by the cation exchange membrane. Electrodeposition of iron group metals can be performed efficiently without being affected. In particular, when the iron group metal ion-containing liquid is an acid waste liquid, the iron group metal electrodeposited on the cathode is dissolved in the conventional method, or the electrodeposition rate of the iron group metal is significantly reduced. According to the invention, even if the acid waste liquid is introduced into the anode chamber, the cathode chamber can be made into a condition suitable for electrodeposition.
- the present inventors solve the above-mentioned problems by making the electrodeposition liquid system contain one or more additives selected from dicarboxylic acids having a specific structure and salts thereof and tricarboxylic acids and salts thereof. As a result, the second invention was completed.
- the gist of the second invention is as follows.
- An anode and a cathode are immersed in a liquid containing Co ions and Fe ions, and a dicarboxylic acid represented by the following formula (1) and a salt thereof and one or more additives selected from a tricarboxylic acid and a salt thereof.
- X 1 , X 2 and X 3 each independently represent H or OH
- X 4 and X 5 each independently represent H, OH or COOM 3
- M 1 , M 2 and M 3 Each independently represents H, a monovalent alkali metal or ammonium ion
- a, b and c each independently represents an integer of 0 or 1.
- X 4 and X 5 do not become COOM 3 at the same time.
- An anode chamber having an anode and a cathode chamber having a cathode are separated by a cation exchange membrane, a liquid containing Co ions and Fe ions is introduced into the anode chamber, and the following formula (1) is introduced into the cathode chamber.
- X 1 , X 2 and X 3 each independently represent H or OH
- X 4 and X 5 each independently represent H, OH or COOM 3
- M 1 , M 2 and M 3 Each independently represents H, a monovalent alkali metal or ammonium ion
- a, b and c each independently represents an integer of 0 or 1.
- X 4 and X 5 do not become COOM 3 at the same time.
- An electrodeposition tank holding a liquid containing Co ions and Fe ions, and one or more additives selected from dicarboxylic acids represented by the following formula (1) and salts thereof, and tricarboxylic acids and salts thereof; And an anode and a cathode provided in the liquid in the electrodeposition tank, and an energizing means for energizing between the anode and the cathode.
- Co and Fe electrodeposition apparatus characterized by depositing Fe and Fe.
- X 1 , X 2 and X 3 each independently represent H or OH
- X 4 and X 5 each independently represent H, OH or COOM 3
- M 1 , M 2 and M 3 Each independently represents H, a monovalent alkali metal or ammonium ion
- a, b and c each independently represents an integer of 0 or 1.
- X 4 and X 5 do not become COOM 3 at the same time.
- An electrodeposition chamber having an anode chamber having an anode, a cathode chamber having a cathode, a cation exchange membrane separating the anode chamber and the cathode chamber, and energization means for energizing between the anode and the cathode And a means for passing a liquid containing Co ions and Fe ions through the anode chamber; a dicarboxylic acid represented by the following formula (1); and a salt thereof; a tricarboxylic acid and a salt thereof; Liquid passing means for passing a liquid containing one or more additives, and supplying electricity between the anode and the cathode to convert Co ions and Fe ions in the liquid in the anode chamber to the cation exchange membrane.
- a Co and Fe electrodeposition apparatus wherein Co and Fe are allowed to pass through and move into the liquid in the cathode chamber to deposit Co and Fe on the cathode.
- X 1 , X 2 and X 3 each independently represent H or OH
- X 4 and X 5 each independently represent H, OH or COOM 3
- M 1 , M 2 and M 3 Each independently represents H, a monovalent alkali metal or ammonium ion, and a, b and c each independently represents an integer of 0 or 1.
- X 4 and X 5 do not become COOM 3 at the same time.
- ⁇ Effect of the second invention> when a waste liquid containing Co ions and Fe ions is energized to deposit Co and Fe on the cathode, a dicarboxylic acid having a specific structure and a salt thereof and a tricarboxylic acid and a salt thereof are selected.
- the liquid property can be made suitable for electrodeposition. Suspended substances with poor sedimentation can be generated or non-conductive precipitates can be generated. Co and Fe can be efficiently electrodeposited and removed at the same time without causing the problem that the energization process cannot be continued due to precipitation.
- the gist of the third invention is as follows.
- a radioactive ion is adsorbed in a waste ion-exchange resin by adsorbing a radioactive substance and contacting an acid heated to 60 ° C. or higher with a waste ion-exchange resin containing a clad composed mainly of iron oxide.
- a method for decontaminating radioactive waste ion exchange resin comprising a step of decontaminating a substance and dissolving and removing the clad.
- an anode chamber in which an anode is installed and a cathode chamber in which a cathode is installed are separated by a cation exchange membrane, and the acid waste liquid is introduced into the anode chamber, and the anode chamber
- the ionic radioactive material in the acid waste liquid permeates through the cation exchange membrane, moves to the cathode chamber, and is electrodeposited on the cathode
- a radioactive ion is adsorbed in the waste ion-exchange resin by adsorbing a radioactive substance and contacting an acid heated to 60 ° C. or higher with a waste ion-exchange resin containing a clad composed mainly of iron oxide.
- a radioactive waste ion exchange resin decontamination apparatus comprising a decontamination means for dissolving and removing a substance and dissolving and removing the clad, the decontamination means comprising a packed tower filled with the waste ion exchange resin, An introduction pipe for introducing the heated acid into the packed tower, a heating means provided in the introduction pipe, and a discharge pipe for discharging the acid waste liquid containing ionic radioactive substances from the packed tower. Characterized decontamination equipment for radioactive waste ion exchange resin.
- An electrodeposition tank having an anode and a cathode, a means for energizing the anode and the cathode, a means for introducing the acid waste liquid into the electrodeposition tank, and a treatment liquid in the electrodeposition tank Means to circulate upstream, and by conducting electricity between the anode and cathode, the ionic radioactive material in the acid waste solution is electrodeposited on the cathode, and the ionic radioactive material is removed from the acid waste solution.
- the decontamination apparatus for radioactive waste ion exchange resin according to [8], wherein the treatment liquid obtained by removing the ionic radioactive substance is reused by the decontamination means.
- the electrodeposition tank includes an anode chamber in which an anode is installed, a cathode chamber in which a cathode is installed, and a cation exchange membrane that separates the anode chamber and the cathode chamber.
- anode chamber in which an anode is installed
- a cathode chamber in which a cathode is installed
- a cation exchange membrane that separates the anode chamber and the cathode chamber.
- the radioactive metal ions adsorbed on the cation exchange resin of the waste ion exchange resin are ion-exchanged with H + ions.
- the clad containing hematite mixed in the waste ion exchange resin can also be efficiently dissolved and removed.
- an acid waste solution containing radioactive metal ions discharged from this decontamination process and iron ions that are dissolved in the clad is introduced into an electrodeposition tank provided with an anode and a cathode, and electricity is passed between the anode and the cathode.
- radioactive metal ions and iron ions can be simultaneously electrodeposited on the cathode and removed, and the electrodeposition treatment liquid can be reused for the decontamination treatment of the waste ion exchange resin.
- decontamination of the waste ion exchange resin and removal of radioactive substances from the acid waste liquid are continued. It is possible to process a large amount of waste ion exchange resin.
- the third invention it is possible to obtain a waste ion exchange resin whose radiation dose is reduced to an extremely low level, and the treated waste ion exchange resin can be incinerated.
- the capacity can be reduced to 1/100 to 1/200.
- Example 21 It is a graph which shows the electrodeposition result by the diammonium citrate alone of Example 18. It is a graph which shows the electrodeposition result by triammonium citrate alone of Example 19. It is a graph which shows the electrodeposition result by triammonium citrate alone of Example 20. 6 is a graph showing the electrodeposition results of triammonium citrate alone in Example 21. 4 is a graph showing the cation exchange membrane permeation test result of Example 22. It is a graph which shows the cation exchange membrane permeation test result (eluent) of Example 23. It is a graph which shows the cation exchange membrane permeation test result (electrodeposition liquid) of Example 23. It is a graph which shows the result of Example 24. 6 is a graph showing the electrodeposition test results of Comparative Experimental Example 2. 7 is a graph showing the electrodeposition test results of Experimental Examples 3 to 9 and Comparative Experimental Example 6.
- FIG. 1 is a system diagram showing an example of an embodiment of a treatment apparatus for an iron group metal ion-containing liquid according to the first invention.
- an anode chamber 2A having an anode 2 in an electrodeposition tank 1 and a cathode chamber 3A having a cathode 3 are separated by a cation exchange membrane 5, and an iron group metal ion is placed in the anode chamber 2A.
- the contained liquid is passed, the catholyte is passed through the cathode chamber 3A, and the anode 2 and the cathode 3 are energized to allow the iron group metal ions in the liquid in the anode chamber 2A to pass through the cation exchange membrane 5.
- the iron group metal is deposited on the cathode 3 by being moved into the liquid in the cathode chamber 3A.
- reference numeral 10 denotes an iron group metal ion-containing liquid storage tank.
- the pump P 1 introduces an iron group metal ion-containing liquid into the anode chamber 2 ⁇ / b> A through the pipe 11, and discharges the iron group metal ion through the pipe 12.
- a circulation system for returning to the contained liquid storage tank 10 is formed.
- 20 is a catholyte tank, a pump P 2 via the pipe 21 by introducing a catholyte to the cathode compartment 3A, the circulatory system back to the catholyte reservoir 20 to discharge fluid through the pipe 22 is formed.
- the waste liquid is introduced directly into the bath in which the cathode is immersed, if the waste liquid is strongly acidic with a pH of less than 2, particularly less than pH 1, the pH is not appropriately adjusted with alkali. There arises a problem that the iron group metal electrodeposited on the cathode is redissolved or electrodeposition itself does not occur.
- the waste liquid may be a strongly acidic liquid having the above pH. The iron group metal can be well removed by electrodeposition.
- the iron group metal ion concentration is about 0.1 to 10,000 mg / L, particularly about 1 to 1000 mg / L. Even low-concentration waste liquids can be treated efficiently.
- the pH of the catholyte used in the first invention is preferably 1 to 9, and more preferably 2 to 8. If the pH of the catholyte is too low, re-dissolution of the iron group metal electrodeposited on the cathode may occur, and the electrodeposition rate may decrease. When the pH of the catholyte is too high, iron group metal hydroxides are likely to be generated as suspended substances in the solution. For this reason, when the pH of the catholyte is out of the above range, it is preferable to appropriately adjust the pH with an alkali or an acid.
- a complexing agent (hereinafter sometimes referred to as an additive) suitable for electrodeposition of iron group metal ions to the catholyte.
- Examples of the additive include dicarboxylic acid having two carboxyl groups in the molecule and a salt thereof (hereinafter sometimes referred to as “dicarboxylic acid (salt)”), tricarboxylic acid having three carboxyl groups in the molecule, and Those selected from salts thereof (hereinafter sometimes referred to as “tricarboxylic acid (salt)”) are preferred. These may use only 1 type and may mix and use 2 or more types. Dicarboxylic acids (salts) and tricarboxylic acids (salts) suppress the generation of suspended substances during electrodeposition due to their chelating effects, and have an excellent effect in improving the electrodeposition effect.
- a monocarboxylic acid having one carboxyl group in the molecule has a weak binding force with an iron group metal ion, and generates a suspended substance composed of an iron group metal hydroxide in the liquid. This causes the problem of non-uniform electrodeposition.
- the binding force with the iron group metal ion is too strong, the iron group metal is retained in the liquid, and the rate of electrodeposition is significantly reduced. Occurs.
- dicarboxylic acid (salt) and tricarboxylic acid (salt) are particularly preferable in that suspended substances are hardly generated and electrodeposition proceeds rapidly.
- the dicarboxylic acid (salt) or tricarboxylic acid (salt) represented by the following formula (1) has 1 to 3 carbon atoms between the carboxyl groups in the molecule, and is derived from its shape. Thus, it is presumed that an appropriate binding force can be obtained with the iron group metal ion.
- X 1 , X 2 and X 3 each independently represent H or OH
- X 4 and X 5 each independently represent H, OH or COOM 3
- M 1 , M 2 and M 3 Each independently represents H, a monovalent alkali metal or ammonium ion
- a, b and c each independently represents an integer of 0 or 1.
- X 4 and X 5 do not become COOM 3 at the same time.
- Suitable dicarboxylic acids for the first invention include, for example, oxalic acid (ethanedioic acid, HOOC—COOH), malonic acid (propanedioic acid, HOOC—CH 2 —COOH), succinic acid (butanedioic acid, HOOC—CH).
- Examples of the tricarboxylic acid include citric acid (HOOC—CH 2 —COH (COOH) —CH 2 —COOH), 1,2,3-propanetricarboxylic acid, and citric acid is particularly preferable.
- examples of salts of these dicarboxylic acids and tricarboxylic acids include alkali metal salts such as sodium salts and potassium salts, and ammonium salts.
- the iron group metal ion-containing liquid contains a plurality of types of iron group metal ions
- an ammonium salt coexists with dicarboxylic acid (salt) and / or tricarboxylic acid (salt).
- dicarboxylic acid salt
- tricarboxylic acid salt
- an iron group metal ion-containing liquid containing Co and Fe is treated according to the present invention, when no ammonium salt is added, Co is generally faster in electrodeposition than Fe, and the electrodeposition layer of Co An Fe electrodeposition layer is formed on the top, but by adding an ammonium salt, the electrodeposition rates of Co and Fe become substantially equal, and Co and Fe are electrodeposited in an alloy form.
- the electrodeposition rates of Co and Fe are different and electrodeposition is performed by separating the Co layer and the Fe layer, the electrodeposition tends to float or peel off due to the difference in the physical properties of Co and Fe, and continuous electrodeposition processing is performed. There is a risk that it will not be possible.
- ammonium salt may be used as long as it generates ammonium ions in the liquid.
- ammonium chloride, ammonium sulfate, ammonium oxalate, and ammonium citrate are preferable.
- These ammonium salts may be used alone or in combination of two or more.
- ammonium dicarboxylate such as ammonium oxalate or ammonium tricarboxylate such as ammonium citrate
- both ammonium salts and additives can be used, and the generation of suspended substances is suppressed by the chelating effect of dicarboxylic acid and tricarboxylic acid. It is possible to obtain the effect and the effect of adjusting the electrodeposition rate of Co and Fe with one agent.
- the concentration of the additive in the catholyte is not particularly limited, but the catholyte introduced into the cathode chamber with respect to the total molar concentration of iron group metal ions in the iron group metal ion-containing solution introduced into the anode chamber.
- the molar concentration of the additive is preferably 0.1 to 50 times, particularly preferably 0.5 to 10 times.
- the additive is 0.01 to 20% by weight, preferably 0.8.
- An aqueous solution containing 1 to 5% by weight of pH 1 to 9, preferably pH 2 to 8 is used. If the amount of the additive is too small, the effect of inhibiting suspended substances due to the use of the additive cannot be sufficiently obtained. If the amount is too large, the chelate effect becomes too large and the electrodeposition rate decreases.
- the above-mentioned additive is oxidatively decomposed when it comes into contact with the anode of the electrodeposition tank, but the electrodeposition tank is separated from the anode chamber and the cathode chamber by a cation exchange membrane. Since the contained electrodeposition liquid does not come into direct contact with the anode, the additive is not oxidized and consumed wastefully. Therefore, the amount of additive to be replenished to the catholyte may be very small, and the amount of chemical used can be reduced.
- the ammonium salt is preferably used in an amount such that the concentration in the catholyte is 0.01 to 20% by weight, preferably 0.1 to 5% by weight. If the concentration of the ammonium salt is too low, the above effect due to the use of the ammonium salt cannot be sufficiently obtained, and if it is too high, the effect is not improved and the amount of chemicals used increases.
- the electrodeposition conditions are not particularly limited, but the current density is preferably 5 to 600 mA / cm 2 with respect to the cathode area in view of electrodeposition efficiency.
- the iron group metal ion-containing liquid is usually a liquid containing one or more ions of iron, manganese, cobalt and nickel, particularly one or more ions of iron, cobalt and nickel, but other than iron group metals. There is no problem even if other metals are included.
- the first invention relates to radioactive iron group metal ions generated from nuclear power plants, such as decontamination waste liquid generated in nuclear power plants and eluents obtained by eluting iron group metal ions from ion exchange resins used in nuclear power plants. It is suitable for the treatment of contained waste liquids, particularly acid waste liquids having a pH of less than 2. From these waste liquids, iron group metal ions can be efficiently removed and the treatment liquid can be reused.
- the apparatus of FIG. 2 includes an eluent storage tank 30 for storing an eluent obtained by eluting iron group metal ions from a waste ion exchange resin, an elution tank 8 that is a packed tower filled with the waste ion exchange resin 40, and an elution tank.
- An iron group metal ion-containing liquid storage tank 10 which is an acid waste liquid storage tank for storing the acid waste liquid discharged from 8 and an electrodeposition tank 1 into which the acid waste liquid from the iron group metal ion-containing liquid storage tank (acid waste liquid storage tank) 10 is introduced.
- a catholyte storage tank 20 for storing the catholyte supplied to the electrodeposition tank 1.
- the electrodeposition tank 1 is configured such that an anode chamber 2A having an anode 2 and a cathode chamber 3A having a cathode 3 are separated by a cation exchange membrane 5, and an iron group metal ion-containing liquid storage tank (acid waste liquid storage tank) 10
- the acid waste liquid from is passed through the anode chamber 2A, and the catholyte is passed through the cathode chamber 3A.
- 9A and 9B are heat exchangers.
- the elution tank 8 is passed upwardly, and the effluent (acid waste liquid) passes through the pipe 32, and the cation exchange membrane 8 in the electrodeposition tank 4 is deteriorated by the heat exchanger 9B.
- Acid waste iron group metal ion-containing solution storage tank (acid waste liquid storage tank) 10 is pumped P 1 is introduced into the anode chamber 2A of the through pipe 11 electrodeposition tank 1, electrodeposition processing liquid eluent storage tank from the pipe 34 30 and recycled as eluent.
- the catholyte in the catholyte storage tank 20 is introduced into the cathode chamber 3 ⁇ / b> A of the electrodeposition tank 1 through the pipe 21 by the pump P ⁇ b> 2 and returned to the catholyte storage tank 20 through the pipe 22.
- the eluent storage tank 30 is appropriately replenished with acid through a pipe 33, and the catholyte storage tank 20 is replenished with a catholyte through a pipe 23.
- the eluent (acid waste liquid) containing ionic radionuclides and clad dissolved material passes through an iron group metal ion-containing liquid storage tank (acid waste liquid storage tank) 10 and is an anode of the electrodeposition tank 1. It is introduced into the chamber 2A.
- iron group metal ions such as radioactive metal ions in the acid waste liquid and iron ions derived from the clad permeate the cation exchange membrane 5 and move to the cathode chamber 3A. Then, it is electrodeposited on the cathode 3.
- the acid waste liquid treatment liquid from which the iron group metal ions have been removed in the electrodeposition tank 1 is returned to the eluent storage tank 30 and recycled.
- the catholyte in the cathode chamber 3 ⁇ / b > A is circulated between the catholyte storage tank 20 by the pump P ⁇ b > 2, and the reduced amount of the catholyte is circulated and reused while being added to the catholyte storage tank 20.
- an acid eluent heated to 60 ° C. or higher as the eluent used for decontamination of the waste ion exchange resin.
- a heated acid eluent radioactive metal ions adsorbed on the cation exchange resin of the waste ion exchange resin can be eluted and removed by ion exchange with H + ions, and mixed into the waste ion exchange resin. It is possible to efficiently dissolve and remove the clad.
- an aqueous solution of an inorganic acid such as sulfuric acid, hydrochloric acid or nitric acid, or an organic acid such as formic acid, acetic acid or oxalic acid can be used. These acids may be used alone or in combination of two or more. It is preferable to use sulfuric acid and / or oxalic acid which does not volatilize when heated and used and does not correspond to a dangerous substance.
- the acid concentration in the eluent has a suitable concentration depending on the acid used.
- the sulfuric acid concentration is preferably 5 to 40% by weight, more preferably 10 to 30% by weight.
- the oxalic acid concentration is preferably 0.1 to 40% by weight, and more preferably 1 to 20% by weight. If the acid concentration is lower than the above range, the dissolution efficiency of hematite ( ⁇ -Fe 2 O 3 ), which is the main component of the clad, decreases.
- the clad exists in the form of being mixed into the waste ion exchange resin or entering the resin, and its main component is hardly soluble hematite, and it is difficult to dissolve with a low concentration of acid.
- the acid concentration in the eluent is high, the amount of hydrogen generated in the subsequent electrodeposition tank becomes excessive, and the electrodeposition efficiency is lowered.
- the radioactive material is highly concentrated by electrodepositing on the cathode what becomes a metal cation, such as cobalt-60 and nickel-63 contained in the radioactive waste ion exchange resin. can do.
- a metal cation such as cobalt-60 and nickel-63 contained in the radioactive waste ion exchange resin.
- the amount of waste can be reduced to 1/100 to 1/200 capacity.
- the electrodeposition tank 1 is a closed system. However, since hydrogen gas is generated from the cathode, it is preferable to use an open system in which the upper part is opened. When replacing the cathode electrodeposited with metal, the replacement is easier if the upper part of the electrodeposition tank is open.
- the eluent is passed through the elution tank 8 in an upward flow, but may be a downward flow. When the waste ion exchange resin is in the form of a powder, it is preferable to make the flow upward because the differential pressure is likely to increase during liquid flow.
- the acid waste liquid and the catholyte may be passed through the cation exchange membrane 5 in the opposite directions. It is also possible to exchange heat between the eluent introduced into the elution tank 8 and the discharged acid waste liquid.
- Example 2 Results In Example 1, it was possible to remove 19% Co and 10% Fe in the simulated acid waste liquid by energizing for 6 hours, and a black electrodeposit was obtained on the cathode. In Comparative Examples 1 and 2, the removal rate of Co and Fe in the solution was 0% even after the energization for 6 hours, and no electrodeposits were seen on the cathode. From Example 1 and Comparative Examples 1 and 2, it can be seen that the method of electrodeposition by moving metal ions to the cathode chamber via the cation exchange membrane without contacting the strong acid waste solution directly to the cathode is effective.
- Results Table 3 shows the presence or absence of suspended solids before and after energization and the liquid pH.
- FIGS. 3 and 4 show the results of analyzing changes in Co and Fe concentrations in the liquid over time for Reference Examples 1 to 7 and Comparative Reference Examples 2 and 6 having no suspended matter both before and after the energization. From the energization result of 8 hours, it can be seen that in Reference Examples 1 to 7, Co and Fe can be simultaneously electrodeposited over time.
- FIG. 5 showing the change over time of the voltage during the continuous test shows that the voltage does not rise even when the current is continued, and the cathode deposit is conductive. From this test, it was found that the electrodeposition treatment can be performed stably for a long time.
- a dicarboxylic acid having a specific structure and a salt thereof and one or more additives selected from a tricarboxylic acid and a salt thereof used for improving the electrodeposition efficiency will be described.
- a dicarboxylic acid having two carboxyl groups in the molecule and a salt thereof (hereinafter sometimes referred to as “dicarboxylic acid (salt)”), and three carboxyl groups in the molecule.
- a tricarboxylic acid and a salt thereof (hereinafter sometimes referred to as “tricarboxylic acid (salt)”) are used. These may use only 1 type and may mix and use 2 or more types.
- the dicarboxylic acid (salt) and the tricarboxylic acid (salt) suppress the generation of suspended substances during the electrodeposition treatment due to the chelating effect, and have an excellent effect in improving the electrodeposition effect.
- monocarboxylic acid having one carboxyl group in the molecule has a weak binding force with Co ions and Fe ions, and a suspended substance composed of Co or Fe hydroxide is generated in the liquid.
- the electrode is not uniformly deposited on the cathode. If a carboxylic acid having four or more carboxyl groups in the molecule is used, the binding force with Co ions and Fe ions is too strong, and Co and Fe are retained in the liquid, and the rate of electrodeposition is significantly reduced. Problems arise.
- a suspended substance is generated during the electrodeposition treatment. It is difficult and electrodeposition proceeds promptly.
- the dicarboxylic acid (salt) or tricarboxylic acid (salt) represented by the formula (1) has 1 to 3 carbon atoms between the most distant carboxyl groups in the molecule, and the shape It is estimated that an appropriate binding force can be obtained between Co ions and Fe ions.
- the dicarboxylic acid (salt) and tricarboxylic acid (salt) suitable for the second invention are the same as the dicarboxylic acid (salt) and tricarboxylic acid (salt) suitable for the first invention.
- an ammonium salt coexists with a dicarboxylic acid (salt) and / or a tricarboxylic acid (salt).
- the electrodeposition rate of Co is usually higher than that of Fe, and an Fe electrodeposition layer is formed on the Co electrodeposition layer.
- an ammonium salt should be added.
- the electrodeposition rates of Co and Fe are substantially equal, and Co and Fe are electrodeposited in an alloy form.
- the electrodeposition rates of Co and Fe are different and electrodeposition is performed by separating the Co layer and the Fe layer, the electrodeposition tends to float or peel off due to the difference in the physical properties of Co and Fe, and continuous electrodeposition processing is performed. There is a risk that it will not be possible.
- the preferred ammonium salt is the same as the preferred ammonium salt in the first invention.
- Ammonium citrate includes monoammonium citrate, diammonium citrate, and triammonium citrate, all of which can be used suitably, but because of the large amount of ammonium in the compound, use triammonium citrate. Is preferred.
- a waste liquid containing Co ions and Fe ions (Co, Fe-containing waste liquid) is introduced into the electrodeposition tank 41, and the above additives are added.
- this additive and an ammonium salt are added and mixed, and electricity is supplied between the anode 42 and the cathode 43 inserted in the liquid by the power source 44, and Co and Fe are simultaneously electrodeposited on the cathode 43.
- the electrodeposition treatment can be performed more suitably.
- the anode chamber 2A provided with the anode 2 of the electrodeposition tank 1 and the cathode chamber 3A provided with the cathode 3 are separated by a cation exchange membrane 5, and Co ions and A waste liquid containing Fe ions (Co, Fe-containing waste liquid) is passed through, and an electrodeposition liquid containing the above-mentioned additive or this additive and an ammonium salt is passed through the cathode chamber 3A.
- Co ions and Fe ions in the liquid in the anode chamber 2A to pass through the cation exchange membrane 5 and move into the liquid in the cathode chamber 3A to deposit Co and Fe on the cathode 3. It is.
- reference numeral 10 denotes a Co, Fe-containing waste liquid storage tank.
- the pump P 1 introduces the Co, Fe-containing waste liquid into the anode chamber 2A via the pipe 11, and discharges the discharged liquid.
- a circulation system that returns to the Co and Fe-containing waste liquid storage tank 10 through the pipe 12 is formed.
- the above additive, or a electrodeposition solution reservoir containing a additive and ammonium salts, the electrodeposition solution through a pipe 21 by the pump P 2 is introduced into the cathode chamber 3A, the discharge liquid pipe 22
- a circulation system that returns to the electrodeposition liquid storage tank 20 is formed.
- the pH of the liquid in which the cathode is immersed is preferably 1 to 9, and more preferably 2 to 8.5. If the pH is too low, re-dissolution of Co or Fe electrodeposited on the cathode may occur, and the electrodeposition rate may decrease. If the pH is too high, Co and Fe hydroxides are likely to be generated as suspended substances in the liquid. When the pH is out of the above range, it is preferable to appropriately adjust the pH with an alkali or an acid.
- the dicarboxylic acid (salt) or tricarboxylic acid (salt) as an additive comes into contact with the anode, it is decomposed by the oxidation reaction of the anode.
- the electrodeposition liquid containing salt) or tricarboxylic acid (salt) does not come into direct contact with the anode, it is possible to prevent the dicarboxylic acid (salt) or tricarboxylic acid (salt) from being oxidized and consumed. is there.
- the electrodeposition tank 1 is a closed system, but it may be an open system with the upper part opened as shown in FIG.
- the electrodeposition tank 1 since hydrogen gas is generated from the cathode, it is preferable to use an open system with the upper part opened.
- the cathode electrodeposited with Co and Fe it is easier to replace the cathode if the upper part of the electrodeposition tank is open.
- the above-mentioned additive is 0.1 to 50 mol times, particularly 0.5 to 10 times the total molar amount of Co and Fe in the liquid in the electrodeposition tank at the start of electrodeposition. It is preferable to add so that it may become mole times.
- the additive in the electrodeposition liquid introduced into the cathode chamber is compared with the total molar concentration of Co and Fe in the Co, Fe-containing waste liquid introduced into the anode chamber.
- the molar concentration is preferably 0.1 to 50 times, particularly preferably 0.5 to 10 times.
- the electrodeposition liquid for example, an aqueous solution having a pH of 1 to 9, preferably 2 to 8.5, containing 0.01 to 20% by weight, preferably 0.1 to 5% by weight of the above-mentioned additive is used.
- the concentration of the ammonium salt in the liquid in the electrodeposition tank is 0.01 to 20% by weight, preferably 0.1 to 5% by weight. It is preferable to use it in an amount. If the concentration of the ammonium salt is too low, the above effect due to the use of the ammonium salt cannot be sufficiently obtained, and if it is too high, the effect is not improved and the amount of chemicals used increases.
- the additive and the ammonium salt may be added so as to satisfy both the preferable addition range of the additive and the preferable addition range of the ammonium salt.
- the electrodeposition conditions are not particularly limited, but the current density is preferably 5 to 600 mA / cm 2 with respect to the cathode area in view of electrodeposition efficiency.
- the Co ion concentration and Fe ion concentration of the liquid containing Co ions and Fe ions to be electrodeposited in the second invention are not particularly limited.
- the second invention is applied to, for example, a liquid containing 0.1 to 5000 mg-Co / L of Co ions, 0.1 to 10,000 mg-Fe / L of Fe ions, and 0.2 to 15000 mg / L in total. be able to.
- the second invention relates to radioactive Co ions and Fe ions generated from nuclear power plants such as decontamination waste liquid generated in nuclear power plants and eluents obtained by eluting metal ions from ion exchange resins used in nuclear power plants. It is suitable for the treatment of the waste liquid containing.
- These waste liquids often contain metal ions other than radioactive Co ions and Fe ions, such as radioactive Ni ions, and even when these metal ions are contained, they can be electrodeposited together with Co and Fe. is there.
- Electrodeposition of Co and Fe in the presence of dicarboxylic acid and tricarboxylic acid 1) Test conditions Using various additives and CoCl 2 and FeCl 3 , 400 mL of an electrodeposition solution having the composition shown in Table 4 was prepared. For those in which no suspended substances were generated, an electrodeposition test was performed using the apparatus of FIG. Energization was performed at 8 hr, 1 A (current density 62.5 mA / cm 2 ). A Pt-plated Ti plate was used for the anode and a Cu plate was used for the cathode.
- Results Table 4 shows the presence or absence of suspended solids before and after energization and the pH of the solution.
- 7 and 8 show the results of analyzing the changes over time in the concentrations of Co and Fe in the liquids of Examples 2 to 8 and Comparative Examples 4 and 8 in which there was no suspended matter both before and after energization. From the energization result of 8 hours, it can be seen that in Examples 2 to 8, Co and Fe could be electrodeposited over time.
- Electrodeposition of Co and Fe with citric acid 1 Test method An energization test was performed under the conditions shown in Table 5 using the apparatus shown in FIG. As the electrodeposition solution, 400 mL was prepared in a 500 mL beaker using CoCl 2, FeCl 3 and citric acid so as to have the composition shown in Table 5. A Pt-plated Ti plate was used for the anode and a Cu plate was used for the cathode.
- Results Table 6 shows the results of the electrodeposition test using citric acid alone, and FIG. 9 shows the changes over time in the concentrations of Co and Fe in the liquid in the current test. It can be seen that the electrodeposition rate of Co and Fe increases as the current density increases for both Co and Fe.
- Electrodeposition test using citric acid and ammonium salt in combination or using ammonium citrate 1 Test method An electrodeposition test was conducted under the conditions shown in Tables 7A and 7B using the apparatus shown in FIG. In Examples 13 to 17, 400 mL was prepared in a 500 mL beaker using CoCl 2 and FeCl 3 and citric acid and / or an ammonium salt shown in Table 7A as the electrodeposition solution, a Pt-plated Ti plate as the anode, For this, a Cu plate was used. In Examples 18 to 21, 400 mL was prepared in a 500 mL beaker using CoSO 4 and Fe 2 (SO 4 ) 3 and ammonium citrate in the addition amounts shown in Table 7B, and the anode was Pt plated. A Ti plate was used and a Cu plate was used for the cathode. For comparison, conditions for electrodeposition with citric acid alone (Example 10 and Example 11 in Table 5) are shown in Table 7A.
- FIG. 11 shows the electrodeposition test results with citric acid alone (Examples 10 and 11)
- FIG. 12 shows the electrodeposition result with citric acid and ammonium oxalate (Example 13) in combination, and citric acid and ammonium chloride in combination.
- the electrodeposition results of (Examples 14 and 15) are shown in FIG. 13, and the electrodeposition results of combined use of citric acid and ammonium sulfate (Example 16) are shown in FIG.
- FIG. 15 shows the electrodeposition results with ammonium oxalate alone (Example 17).
- k is a reaction rate constant (proportional constant when the rate of decrease in concentration is proportional to the concentration), and indicates that the electrodeposition rate is faster as k is larger.
- FIG. 11 shows that, with citric acid alone, the electrodeposition rate of Co is fast, but the electrodeposition of Fe is slow. Therefore, it is considered that in the electrodeposition with citric acid alone, the electrodeposited Fe is formed on the electrodeposited Co.
- both Co and Fe can be rapidly electrodeposited with one agent by oxalic acid and ammonium ions which are dicarboxylic acids.
- FIG. 20 shows the changes over time in the Co and Fe concentrations on the eluent side and electrodeposition liquid side in Example 22.
- 21 and 22 show the changes over time in the Co and Fe concentrations on the eluent side and electrodeposition liquid side in Example 23, respectively.
- Example 22 and Example 23 were prepared by adding 2 hydrochloric acid (1: 1 mixture of 35% hydrochloric acid and pure water) and 2 nitric acid (1: 1 mixture of 60% nitric acid and pure water), respectively.
- 2 hydrochloric acid 1: 1 mixture of 35% hydrochloric acid and pure water
- 2 nitric acid 1: 1 mixture of 60% nitric acid and pure water
- the amount of electrodeposition was measured with an atomic absorption photometer after completely dissolving with the solution mixed in step 3
- the amount of increase in Co and Fe in the electrodeposition solution was calculated from the amount of decrease in Co and Fe in the eluent. Since it was in agreement with the subtracted amount, it was confirmed that Co ions and Fe ions in the eluent permeated the cation exchange membrane and were electrodeposited on the cathode.
- an acid hereinafter sometimes referred to as an eluent
- a waste ion exchange resin that adsorbs a radioactive substance and includes a clad mainly composed of iron oxide.
- the contact is made to elute and remove the ionic radioactive material in the waste ion exchange resin, and the clad is dissolved and removed.
- the radioactive waste ion exchange resin to be decontaminated adsorbs a radioactive substance that becomes a cation in the eluent and is oxidized like a radioactive metal component such as cobalt-60 and nickel-63.
- a radioactive metal component such as cobalt-60 and nickel-63.
- a clad composed mainly of iron.
- iron oxide as a main component means that iron oxide is contained in the cladding in an amount of 50% by weight or more.
- the amount of radioactive material adsorbed on the waste ion exchange resin and the clad content There is no particular limitation on the amount of radioactive material adsorbed on the waste ion exchange resin and the clad content.
- an aqueous solution of an inorganic acid such as sulfuric acid, hydrochloric acid or nitric acid, or an organic acid such as formic acid, acetic acid or oxalic acid can be used.
- an inorganic acid such as sulfuric acid, hydrochloric acid or nitric acid, or an organic acid such as formic acid, acetic acid or oxalic acid
- organic acid such as formic acid, acetic acid or oxalic acid
- sulfuric acid and / or oxalic acid which hardly evaporates when heated to 60 ° C. or higher and does not fall under hazardous materials.
- the acid concentration in the eluent has a suitable concentration depending on the acid used.
- the sulfuric acid concentration is preferably 5 to 40% by weight, more preferably 10 to 30% by weight.
- the oxalic acid concentration is preferably 0.1 to 40% by weight, and more preferably 1 to 20% by weight. If the acid concentration is lower than the above range, the dissolution efficiency of hematite ( ⁇ -Fe 2 O 3 ), which is the main component of the clad, decreases. That is, the clad is present in a form mixed in or entering the waste ion exchange resin, the main component of which is hardly soluble hematite, and it is difficult to dissolve with a low concentration of acid. If the acid concentration in the eluent is high, the amount of hydrogen generated in the subsequent electrodeposition process becomes excessive, and the electrodeposition efficiency decreases.
- the eluent is heated to 60 ° C. or higher, preferably 70 to 120 ° C., more preferably 80 to 100 ° C. If this temperature is too low, the dissolution efficiency of the clad is poor, and if it is too high, water evaporation and acid volatilization become excessive, which is not preferable in terms of work.
- the method for contacting the heated eluent with the waste ion exchange resin is not particularly limited, and may be a batch type in which the waste ion exchange resin is charged into the eluent and stirred, as shown in FIG.
- a flow-through type in which the eluent is passed through a packed column filled with waste ion exchange resin may be used.
- the contact time between the eluent and the waste ion exchange resin is preferably about 0.5 to 24 hours, and particularly preferably about 2 to 12 hours.
- the flow rate is preferably about 0.2 to 10 hr ⁇ 1 with respect to the packed column volume.
- the ionic radioactive material adsorbed on the waste ion exchange resin is eluted and the clad mixed in the waste ion exchange resin is dissolved to contain an eluent (hereinafter referred to as acid waste liquid).
- acid waste liquid an eluent
- the above-mentioned apparatus shown in FIG. 2 is suitable as an apparatus for decontaminating waste ion-exchange resin and reusing the acid waste liquid obtained by the decontamination process by electrodeposition.
- the apparatus of FIG. 2 includes an eluent storage tank 30 that stores an eluent, an elution tank 8 that is a packed tower filled with a waste ion exchange resin 40, and an acid waste liquid storage tank that stores an acid waste liquid discharged from the elution tank 8. 10, an electrodeposition tank 1 into which the acid waste liquid from the acid waste liquid storage tank 10 is introduced, and a storage tank 20 for storing the electrodeposition liquid (catholyte) supplied to the electrodeposition tank 1.
- the electrodeposition tank 1 has a structure in which an anode chamber 2A having an anode 2 and a cathode chamber 3A having a cathode 3 are separated by a cation exchange membrane 5, and an acid waste liquid is passed through the anode chamber 2A, and electrodeposition is performed.
- the liquid (catholyte) is passed through the cathode chamber 3A.
- 9A and 9B are heat exchangers. Any means may be used as long as the heat exchanger 9A can be heated and the heat exchanger 9B can be cooled, and an electric heater can be used as the heat exchanger 9A.
- the effluent (acid waste liquid) passes through the pipe 32, and the heat exchanger 9B reduces the deterioration of the cation exchange membrane 5 in the electrodeposition tank 1 to a temperature lower than 60 ° C., for example, 10 ° C. or higher and lower than 60 ° C.
- Acid waste acid waste liquid storage tank 10 by the pump P 1 is introduced into the anode chamber 2A of the through pipe 11 electrodeposition tank 1, electrodeposition processing liquid is circulated in the eluent reservoir 30 from the pipe 34, re as eluent Used.
- the electrodeposition liquid (catholyte) in the storage tank 20 is introduced into the cathode chamber 3 ⁇ / b> A of the electrodeposition tank 1 through the pipe 21 by the pump P 2 and returned to the storage tank 20 through the pipe 22.
- the eluent storage tank 30 is appropriately replenished with acid from the pipe 33, and the reservoir 20 is appropriately replenished with the electrodeposition liquid (catholyte) from the pipe 23.
- the ionic radioactive material adsorbed on the waste ion exchange resin 40 is eluted and removed. Then, the clad mixed in the waste ion exchange resin 40 or entering the resin particles is dissolved and removed.
- an eluent (acid waste liquid) containing ionic radioactive material and clad dissolved material is introduced into the anode chamber 2A of the electrodeposition tank (electrodeposition cell) 1 through the acid waste liquid storage tank 10. Is done.
- the radioactive metal ions in the acid waste liquid and the iron ions derived from the cladding permeate the cation exchange membrane 5 and move to the cathode chamber 3 ⁇ / b> A. Is electrodeposited.
- the acid waste liquid treatment liquid from which radioactive metal ions and iron ions have been removed in the electrodeposition tank 1 is returned to the eluent storage tank 30 and recycled.
- the electrodeposition liquid in the cathode chamber 3 ⁇ / b > A is circulated between the storage tank 20 by the pump P ⁇ b > 2 and is circulated and reused while the reduced amount of the electrodeposition liquid is added to the storage tank 20.
- the electrodeposition solution includes dicarboxylic acid having two carboxyl groups in the molecule and a salt thereof (hereinafter sometimes referred to as “dicarboxylic acid (salt)”), and three carboxyl groups in the molecule. It is preferable to use an aqueous solution containing one or more additives selected from tricarboxylic acids having a salt and salts thereof (hereinafter sometimes referred to as “tricarboxylic acids (salts)”).
- Dicarboxylic acid (salt) and tricarboxylic acid (salt) suppress the generation of suspended substances during electrodeposition due to their chelating effect, and have an excellent effect in improving the electrodeposition effect.
- a radioactive metal ion such as Co-60 (the radioactive material is not limited to Co-60 at all.
- the bonding force with Fe ions from the clad is weak, and a suspended substance composed of Co or Fe hydroxide is generated in the liquid, or the electrode is not uniformly electrodeposited on the cathode.
- the binding force with Co ions and Fe ions is too strong, and Co and Fe are retained in the liquid, and the rate of electrodeposition is significantly reduced. Problems arise.
- dicarboxylic acid (salt) and tricarboxylic acid (salt) are preferable in that suspended substances are hardly generated and electrodeposition proceeds rapidly.
- the dicarboxylic acid (salt) or tricarboxylic acid (salt) represented by the formula (1) has 1 to 3 carbon atoms between the carboxyl groups in the molecule, and is derived from its shape. Thus, it is estimated that an appropriate binding force can be obtained between Co ions and Fe ions.
- the dicarboxylic acid (salt) and tricarboxylic acid (salt) suitable for the third invention are the same as the dicarboxylic acid (salt) and tricarboxylic acid (salt) suitable for the first invention.
- an ammonium salt is preferably present together with a dicarboxylic acid (salt) and / or a tricarboxylic acid (salt).
- the electrodeposition rate of Co is usually higher than that of Fe, and an Fe electrodeposition layer is formed on the Co electrodeposition layer.
- an ammonium salt should be added.
- the electrodeposition rates of Co and Fe are substantially equal, and Co and Fe are electrodeposited in an alloy form. If the electrodeposition rates of Co and Fe are different and electrodeposition is performed separately for the Co layer and the Fe layer, the electrodeposit tends to float or peel off, and there is a possibility that continuous electrodeposition processing cannot be performed.
- the preferred ammonium salt is the same as the preferred ammonium salt in the first invention.
- the pH of the electrodeposition solution is preferably 1 to 9, and more preferably 2 to 8.5. If the pH of the electrodeposition solution is too low, Co or Fe electrodeposited on the cathode may be redissolved, and the electrodeposition rate may be reduced. If the pH of the electrodeposition solution is too high, Co and Fe hydroxides are likely to be generated as suspended substances in the solution.
- the pH of the electrodeposition liquid is out of the above range, it is preferable to adjust the pH appropriately with an alkali or an acid.
- the acid used for pH adjustment it is preferable to use the same dicarboxylic acid and / or tricarboxylic acid as the above-mentioned additive in the electrodeposition liquid.
- an aqueous solution containing 0.01 to 20% by weight, preferably 0.1 to 5% by weight of the above-mentioned additive, and having a pH of 1 to 9, preferably 2 to 8.5 is used.
- the amount of the additive in the electrodeposition solution is too small, the effect of suppressing suspended substances due to the use of the additive cannot be sufficiently obtained, and if too much, the chelating effect becomes too large and the electrodeposition rate is too high. descend.
- the ammonium salt in the electrodeposition solution is 0.01 to 20% by weight, preferably 0.1 to 5% by weight. If the concentration of the ammonium salt in the electrodeposition solution is too low, the above-described effect due to the use of the ammonium salt cannot be obtained sufficiently, and if it is too high, the effect is not improved and the amount of chemical used is wasted.
- the electrodeposition conditions are not particularly limited, but the current density is preferably 5 to 600 A / cm 2 with respect to the cathode area in view of electrodeposition efficiency.
- FIG. 2 shows an example of a decontamination apparatus suitable for the implementation of the third invention, and the decontamination apparatus of the third invention is not limited to the illustrated one.
- the eluent is passed through the elution tank 8 in an upward flow, but it may be a downward flow.
- the waste ion exchange resin is in the form of a powder, it is preferable to make the flow upward because the differential pressure is likely to increase during liquid flow.
- the acid waste solution and the electrodeposition solution may be passed through the cation exchange membrane 5 in the opposite directions. It is also possible to exchange heat between the eluent introduced into the elution tank 8 and the discharged acid waste liquid.
- the electrodeposition tank 1 is a closed system, but since hydrogen gas is generated from the cathode, it is preferable to use an open system with the top open. When replacing the cathode electrodeposited with metal, the replacement is easier if the upper part of the electrodeposition tank is open.
- the third invention relates to a waste ion exchange resin used for purification of water systems directly touching fuel rods, such as a reactor water purification system and a fuel storage pool water purification system, and a primary cooling system contaminated with radioactive substances in a nuclear power plant.
- Adsorb ionic radioactive materials such as waste ion exchange resin used for the treatment of decontamination waste liquid discharged when radioactive materials are chemically removed from the surface of equipment, pipes, and metal parts of systems containing them At the same time, it is effectively applied to waste ion exchange resin containing a clad composed mainly of iron oxide.
- Example 1 500 mL of an eluent (aqueous solution) having an acid concentration and pH shown in Table 9 was prepared, and 1 g of a simulated clad (manufactured by High-Purity Chemical Laboratory, ⁇ -Fe 2 O 3 , manufacturer's nominal diameter 1 ⁇ m) was placed in the eluent. The dissolution test was conducted at the liquid temperature and dissolution time shown in Table 9. The Fe (cladding) dissolution rate was examined from the Fe concentration in the eluent, and the results are shown in Table 9.
- a simulated clad manufactured by High-Purity Chemical Laboratory, ⁇ -Fe 2 O 3 , manufacturer's nominal diameter 1 ⁇ m
- Example 24 The mixed resin adsorbing Co was dissolved in an aqueous solution in which 96 mg of cobalt (II) chloride hexahydrate was dissolved, and the powdered H-type cation exchange resin (manufactured by Mitsubishi Chemical Corporation, exchange capacity: 5.1 meq / g, particle size) 10-200 ⁇ m: 95%) and powdered OH type anion exchange resin (Mitsubishi Chemical Corporation, exchange capacity 4.1 meq / g, particle size 0-100 ⁇ m: 74%, 10-250 ⁇ m: 93%). It was prepared by mixing 0 g at a time and stirring for 12 hr.
- cobalt (II) chloride hexahydrate was dissolved in an aqueous solution in which 96 mg of cobalt (II) chloride hexahydrate was dissolved, and the powdered H-type cation exchange resin (manufactured by Mitsubishi Chemical Corporation, exchange capacity: 5.1 meq / g, particle size)
- Co and Fe in the simulated acid waste solution after 6 hours of energization were measured with an atomic absorption photometer. As a result of energization for 6 hours, 19% of Co and 10% of Fe in the simulated acid waste solution could be removed and A kimono was obtained.
- the metal ions were moved to the cathode chamber through the cation exchange membrane without bringing the strongly acidic waste liquid into direct contact with the cathode, so that the electrodeposition could be efficiently performed.
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Abstract
Description
これらの放射性物質を含む廃棄物は、最終的にセメント等の固化助材と混練して安定化した後に、埋設処分される。埋設処分する際の費用は、内包する放射性物質の量で異なり、放射性物質濃度が高いほど高額となる。このため、高線量率の廃棄物はできるだけ減容した後に、固化体の埋設廃棄物とすることが経済的である。具体的には、イオン交換樹脂から放射性物質を固形物として分離し、遮蔽容器内に封じ込めることができれば、減容化の面で望ましい。放射性物質が除去された廃イオン交換樹脂は、処分費用が安価な低線量率の廃棄物であり、さらに、廃イオン交換樹脂を焼却可能なレベルまで放射性物質を除去できれば、焼却処理により、大幅な減容が達成できる。
本発明者らは、陽極を備えた陽極室と陰極を備えた陰極室とをカチオン交換膜で隔離した電着槽の陽極室に鉄族金属イオン含有液を導入し、陰極室に陰極液を導入して、陽極と陰極間に通電することにより、陽極室内の液中の鉄族金属イオンを陰極室内の陰極液中に移動させて陰極上に鉄族金属を析出させるようにすることにより、鉄族金属イオン含有液の液性状に左右されることなく、適切な電着条件にて鉄族金属を電着除去することができることが分かり、第1発明を完成させた。
第1発明によれば、鉄族金属イオン含有液を導入する陽極室と、鉄族金属を析出させる陰極室をカチオン交換膜で隔離していることから、鉄族金属イオン含有液の液性状に左右されることなく、効率良く鉄族金属の電着が可能である。特に、鉄族金属イオン含有液が、酸廃液である場合、従来法では陰極に電着する鉄族金属が溶解してしまったり、鉄族金属の電着速度が著しく低下したりするが、本発明によれば、陽極室に酸廃液が導入されても、陰極室を電着に適した条件とすることができる。
本発明者らは、電着液系内に、特定の構造をとるジカルボン酸及びその塩並びにトリカルボン酸及びその塩から選ばれる1種以上の添加剤を存在させることにより、上記課題を解決することができることが分かり、第2発明を完成させた。
M1OOC-(CHX1)a-(NH)b-(CX2X4)c-CX3X5-COOM2
…(1)
式(1)中、X1,X2,X3は各々独立にH又はOHを表し、X4,X5は各々独立にH、OH又はCOOM3を表し、M1,M2,M3は各々独立にH、1価のアルカリ金属又はアンモニウムイオンを表し、a,b,cは各々独立に0又は1の整数を表す。ただし、式(1)において、X4とX5は同時にCOOM3となることはない。
M1OOC-(CHX1)a-(NH)b-(CX2X4)c-CX3X5-COOM2
…(1)
式(1)中、X1,X2,X3は各々独立にH又はOHを表し、X4,X5は各々独立にH、OH又はCOOM3を表し、M1,M2,M3は各々独立にH、1価のアルカリ金属又はアンモニウムイオンを表し、a,b,cは各々独立に0又は1の整数を表す。ただし、式(1)において、X4とX5は同時にCOOM3となることはない。
M1OOC-(CHX1)a-(NH)b-(CX2X4)c-CX3X5-COOM2
…(1)
式(1)中、X1,X2,X3は各々独立にH又はOHを表し、X4,X5は各々独立にH、OH又はCOOM3を表し、M1,M2,M3は各々独立にH、1価のアルカリ金属又はアンモニウムイオンを表し、a,b,cは各々独立に0又は1の整数を表す。ただし、式(1)において、X4とX5は同時にCOOM3となることはない。
M1OOC-(CHX1)a-(NH)b-(CX2X4)c-CX3X5-COOM2
…(1)
式(1)中、X1,X2,X3は各々独立にH又はOHを表し、X4,X5は各々独立にH、OH又はCOOM3を表し、M1,M2,M3は各々独立にH、1価のアルカリ金属又はアンモニウムイオンを表し、a,b,cは各々独立に0又は1の整数を表す。ただし、式(1)において、X4とX5は同時にCOOM3となることはない。
第2発明によれば、CoイオンとFeイオンを含む廃液に通電して、陰極上にCoとFeを電着させるにあたって、特定の構造をとるジカルボン酸及びその塩並びにトリカルボン酸及びその塩から選ばれる1種以上の添加剤を液中に共存させることにより、液性状を電着に適したものとすることができ、沈降性の悪い懸濁物質が発生したり、導電性のない析出物が析出して通電処理を継続できなくなるといった問題を引き起こすことなく、CoとFeを同時に効率良く電着させて除去することが可能となる。
本発明者らは、所定温度に加温された酸を用いることにより、廃イオン交換樹脂中のイオン状放射性物質を溶離除去すると共に、クラッドをも溶解除去することができること、この除染処理で得られた酸廃液は、電着処理して循環再利用できることが分かり、第3発明を完成させた。
第3発明によれば、廃イオン交換樹脂に60℃以上に加温した酸を接触させるため、廃イオン交換樹脂のカチオン交換樹脂に吸着している放射性金属イオンをH+イオンとイオン交換して溶離除去できるとともに、廃イオン交換樹脂中に混入しているヘマタイトを含むクラッドをも効率良く溶解除去することができる。
以下に図面を参照して第1発明の実施の形態を詳細に説明する。
…(1)
式(1)中、X1,X2,X3は各々独立にH又はOHを表し、X4,X5は各々独立にH、OH又はCOOM3を表し、M1,M2,M3は各々独立にH、1価のアルカリ金属又はアンモニウムイオンを表し、a,b,cは各々独立に0又は1の整数を表す。ただし、式(1)において、X4とX5は同時にCOOM3となることはない。
第1発明は、原子力発電所において発生する除染廃液や、原子力発電所で使用されたイオン交換樹脂から鉄族金属イオンを溶離させた溶離液といった、原子力発電所等から生じる放射性鉄族金属イオン含有廃液、とりわけ、pHが2未満の酸廃液の処理に好適であり、これらの廃液から、鉄族金属イオンを効率的に除去して処理液を再利用することができる。
溶離液貯槽30には適宜酸が配管33より補給され、陰極液貯槽20には配管23より陰極液が補給される。
陰極室3A内の陰極液は、ポンプP2により陰極液貯槽20との間を循環させ、陰極液の減少分を陰極液貯槽20に添加しつつ循環再利用する。
図1,2の装置では、電着槽1は閉鎖系となっているが、陰極から水素ガスが発生するため、上部を開放した開放系とするのが好ましい。金属が電着した陰極を交換する際にも、電着槽の上部が開放されていた方が交換が容易となる。図2において、溶離液は、溶離槽8に上向流で通液されているが、下向流であってもよい。廃イオン交換樹脂が粉末状である場合には、通液の際に差圧上昇しやすいため、上向流とすることが好ましい。電着槽1において、酸廃液と陰極液とはカチオン交換膜5を介して逆方向に通液されてもよい。溶離槽8に導入される溶離液と排出される酸廃液とを熱交換することも可能である。
以下に実施例を挙げて第1発明をより具体的に説明する。
1)試験条件
<実施例1>
CoCl2及びFeCl3と硫酸を水に溶解させて表1に示す性状の模擬酸廃液を調製した。クエン酸を水に溶解させて表1に示す性状の模擬電着液(陰極液)を調製した。図1の装置を用いて、Co、Feの電着試験を行った。電着条件は表1の通りである。陽極はPtメッキTi板、陰極はCu板を使用した。6hr通電後の模擬酸廃液中のCo及びFeを原子吸光光度計にて測定した。
表2に示す性状の模擬酸廃液を400mL調製して500mLビーカーに入れ、この中に陰極(Cu板)と陽極(PtメッキTi板)を挿入して通電を行った。カチオン交換膜は使用しなかった。電着条件は表2の通りである。6hr後の模擬酸廃液中のCo及びFeを原子吸光光度計にて測定した。
実施例1においては、6hrの通電により、模擬酸廃液中のCoが19%、Feが10%除去でき、陰極に黒色の電着物が得られた。比較例1、2では、通電6hr後も液中のCoとFeの除去率は0%であり、陰極に電着物は見られなかった。実施例1及び比較例1、2より、強酸廃液を直接陰極に接触させることなく、カチオン交換膜を介して金属イオンを陰極室に移動させて電着させる方法が有効であることがわかる。
1)試験条件
CoCl2及びFeCl3と表3に示す添加剤を用いて、表3に示す組成の液を400mL調製し、懸濁物質が発生しなかったものについて、比較例1と同様に電着試験を行った。通電は8hr行った。
表3に通電前後での懸濁物質の発生の有無と液pHを示した。
通電前後の両方において懸濁物質がない参考例1~7、比較参考例2,6について、液中のCoとFeの濃度の経時変化を解析した結果を図3、4に示す。8hrの通電結果から、参考例1~7は、経時的にCo及びFeを同時電着できていることがわかる。
電着を継続的に行うことができれば、電極単位面積当たりの電着量を大きくすることが可能となり、廃棄物量の低減につながる。そのため、Co、Feを補充しながら長時間の連続電着が可能かを確認した。
1)試験方法
CoCl2及びFeCl3とクエン酸を用いて、100mg-Co/L、100mg-Fe/L、クエン酸3,350mg/L(CoとFeの合計モル量に対して5モル倍)、pH2.2の液を500mLビーカーに400mLを調製し、比較例1と同様の条件にて電着試験を開始し、2hrごとに固体塩化物のCoとFeを50mg/L相当分ずつ追加添加して、長時間の電着試験を行った。
2)結果と考察
通電により、陰極には黒色の電着物が付着した。連続試験時の電圧の経時変化を示す図5より、通電を継続しても電圧は上昇しておらず、陰極の析出物は導電性であることがわかる。本試験により、長時間安定して電着処理できることがわかった。
以下に第2発明の実施の形態を詳細に説明する。
以下に実施例を挙げて第2発明をより具体的に説明する。
1)試験条件
各種の添加剤とCoCl2及びFeCl3を用いて、表4に示す組成の電着液400mLを調製し、懸濁物質が発生しなかったものについて、図6の装置を用いて、電着試験を行った。通電は8hr、1A(電流密度62.5mA/cm2)で行った。陽極にはPtメッキTi板を、陰極にはCu板を使用した。
表4に通電前後での懸濁物質の発生の有無と液pHを示した。
通電前後の両方において懸濁物質がない実施例2~8、比較例4,8の電着液について、液中のCoとFeの濃度の経時変化を解析した結果を図7、8に示す。8hrの通電結果から、実施例2~8においては、経時的にCo及びFeを電着できていることがわかる。
1)試験方法
図6に示す装置を用い、表5に示す条件で通電試験を行った。電着液はCoCl2及びFeCl3とクエン酸を用いて、表5に示す組成となるように500mLビーカーに400mLを調製した。陽極にはPtメッキTi板を、陰極にはCu板を使用した。
表6にクエン酸単独での電着試験結果を、図9に通電試験における液中CoとFeの濃度の経時変化を示す。Co、Feともに電流密度を上げるほどCo、Feの電着速度が速くなることがわかる。
電着を継続的に行うことができれば、電極単位面積当たりの電着量を大きくすることが可能となり、廃棄物量の低減につながる。そのため、Co、Feを補充しながら長時間の連続電着が可能かを確認した。
1)試験方法
表5の実施例10と同じ条件にて電着試験を開始し、2hrごとに固体塩化物のCoとFeを50mg/L相当分ずつ追加添加して、長時間の電着試験を行った。その他の条件は実施例10と同じ条件である。
2)結果と考察
通電により、陰極には黒色の電着物が付着した。連続試験時の電圧の経時変化を示す図10より、通電を継続しても電圧は上昇しておらず、陰極の析出物は導電性であることがわかる。本試験により、長時間安定して電着処理できることがわかった。
1)試験方法
図6に示す装置を用い、表7A,7Bの条件にて電着試験を行った。
実施例13~17では、電着液はCoCl2及びFeCl3とクエン酸及び/又は表7Aに示すアンモニウム塩を用いて、500mLビーカーに400mLを調製し、陽極にはPtメッキTi板を、陰極にはCu板を使用した。実施例18~21では、電着液はCoSO4及びFe2(SO4)3と、クエン酸アンモニウムを表7Bに示す添加量で用いて、500mLビーカーに400mLを調製し、陽極にはPtメッキTi板を、陰極にはCu板を使用した。比較のため、クエン酸単独での電着条件(表5の実施例10と実施例11)を表7Aに付記した。
電着液をクエン酸水溶液、溶離液を硫酸水溶液とした場合に、通電によりCo、Feがカチオン交換膜を透過することを確認した。
1)試験方法
カチオン交換膜を配した図1に示す電着装置を用いて、通電試験を行った(実施例22、実施例23)。試験条件を表8に示す。
図20に実施例22における溶離液側と電着液側のCoとFe濃度の経時変化を示す。図21,22に実施例23における溶離液側と電着液側のCoとFe濃度の経時変化をそれぞれ示す。
以下に第3発明の実施の形態を詳細に説明する。
以下に実験例及び実施例を挙げて第3発明をより具体的に説明する。
表9に示す酸濃度及びpHの溶離液(水溶液)を500mL調製し、この溶離液中に模擬クラッド(高純度化学研究所製、α-Fe2O3、メーカー公称径1μm)1gを入れ、表9に示す液温及び溶解時間で溶解試験を行った。
溶離液中のFe濃度から、Fe(クラッド)溶解率を調べ、結果を表9に示した。
Coを吸着した混合樹脂は、塩化コバルト(II)6水和物96mgを溶解した水溶液に、粉末状H形カチオン交換樹脂(三菱化学(株)社製、交換容量:5.1meq/g、粒度10-200μm:95%)と粉末状OH形アニオン交換樹脂(三菱化学(株)社製、交換容量4.1meq/g、粒度0-100μm:74%、10-250μm:93%)を40.0gずつ混合し、12hr攪拌することにより調製した。12hr後に上澄水中のCo濃度を原子吸光光度計にて測定した結果、検出下限値以下であったことから、Coイオンのほぼ全量がイオン交換樹脂に吸着されたことが確認された。前記混合樹脂に模擬クラッドとしての鉄酸化物(高純度化学研究所製、α-Fe2O3、メーカー公称径1μm)4.0gを添加して混合したものを模擬廃樹脂とした。その後、この模擬廃樹脂を90℃に加温した10重量%硫酸溶離液(水溶液)1.6L中に投入し、ホットスターラーで加熱攪拌しながら90℃に維持し、溶解挙動を確認した。
10重量%硫酸溶離液に模擬廃樹脂を投入後、所定時間毎に硫酸溶離液を数mLずつ採取し、濾過したサンプル中のFeを原子吸光光度計にて分析すると共に、CoをICP-MSにて分析した。
その結果、Feについては、図23に示すとおり、添加した模擬クラッド中のFe量のほぼ100%が硫酸溶離液中に溶解しており、模擬クラッド溶解後にカチオン交換樹脂への再吸着も起こっていないことが分かった。2時間以降で溶解率が100%を超えているのは、加温による溶離液中の水の蒸発のためである。Coについては、添加した塩化コバルト中のCo量のほぼ100%が硫酸溶離液中に溶離しており、樹脂から良好にCoイオンを溶離できていることが確認できた。
CoCl2及びFeCl3と硫酸を水に溶解させて表10に示す性状の模擬酸廃液を調製し、また、クエン酸を水に溶解させて表10に示す性状の模擬電着液(陰極液)を調製して、図1の装置を用いて、Co、Feの電着試験を行った。図1中、12は、電着処理液を酸廃液貯槽10に戻す配管である。電着条件は表10の通りである。陽極はPtメッキTi板、陰極はCu板を使用した。
この電着装置では、強酸性の廃液を直接陰極に接触させることなく、カチオン交換膜を介して金属イオンを陰極室に移動させて、効率的に電着させることができた。
各種の添加剤とCoCl2及びFeCl3を用いて、表11に示す組成の電着液400mLを調製し、懸濁物質が発生しなかったものについて、図6の装置を用いて、電着試験を行った。通電は8hr、1A(電流密度62.5mA/cm2)で行った。陽極にはPtメッキTi板を、陰極にはCu板を使用した。
表11に通電前後での懸濁物質の発生の有無と液pHを示した。通電前後の両方において懸濁物質がない実験例3~9、比較実験例2,6の電着液について、液中のCoとFeの濃度の経時変化を解析した結果を図24、25に示す。8hrの通電結果から、実験例3~9においては、経時的にCo及びFeを電着できていることがわかる。
本出願は、2013年10月24日付で出願された日本特許出願2013-221320、2013年10月24日付で出願された日本特許出願2013-221321、2013年10月24日付で出願された日本特許出願2013-221322及び2014年3月7日付で出願された日本特許出願2014-045235に基づいており、その全体が引用により援用される。
Claims (33)
- 陽極を備えた陽極室と陰極を備えた陰極室とをカチオン交換膜で隔離し、該陽極室に鉄族金属イオン含有液を導入し、該陰極室に陰極液を導入し、該陽極と該陰極間に通電することにより、該陽極室内の液中の鉄族金属イオンを該カチオン交換膜を透過させて該陰極室内の液中に移動させ、該陰極上に該鉄族金属を析出させることを特徴とする鉄族金属イオン含有液の処理方法。
- 前記鉄族金属は、鉄、コバルト、及びニッケルから選ばれる1種以上であることを特徴とする請求項1に記載の鉄族金属イオン含有液の処理方法。
- 前記鉄族金属イオン含有液は、pH2未満の酸廃液であることを特徴とする請求項1又は2に記載の鉄族金属イオン含有液の処理方法。
- 前記陰極液は、ジカルボン酸及びその塩並びにトリカルボン酸及びその塩から選ばれる1種以上の添加剤を含むことを特徴とする請求項1乃至3のいずれか1項に記載の鉄族金属イオン含有液の処理方法。
- 陽極を備えた陽極室と、陰極を備えた陰極室と、該陽極室と陰極室とを隔離するカチオン交換膜とを有する電着槽と、該陽極及び陰極間に通電する通電手段と、該陽極室に鉄族金属イオン含有液を通液する通液手段と、該陰極室に陰極液を通液する通液手段とを有し、該陽極と該陰極間に通電することにより、該陽極室内の液中の鉄族金属イオンを該カチオン交換膜を透過させて該陰極室内の液中に移動させ、該陰極上に該鉄族金属を析出させることを特徴とする鉄族金属イオン含有液の処理装置。
- 前記鉄族金属は、鉄、コバルト、及びニッケルから選ばれる1種以上であることを特徴とする請求項5に記載の鉄族金属イオン含有液の処理装置。
- 前記鉄族金属イオン含有液は、pH2未満の酸廃液であることを特徴とする請求項5又は6に記載の鉄族金属イオン含有液の処理装置。
- 前記陰極液は、ジカルボン酸及びその塩、並びにトリカルボン酸及びその塩から選ばれる1種以上の添加剤を含むことを特徴とする請求項5乃至7のいずれか1項に記載の鉄族金属イオン含有液の処理装置。
- Coイオン及びFeイオンと、下記式(1)で表されるジカルボン酸及びその塩並びにトリカルボン酸及びその塩から選ばれる1種以上の添加剤とを含む液に陽極と陰極を浸漬し、該陽極と陰極に通電することにより、該陰極上にCo及びFeを析出させることを特徴とするCoとFeの電着方法。
M1OOC-(CHX1)a-(NH)b-(CX2X4)c-CX3X5-COOM2 …(1)
式(1)中、X1,X2,X3は各々独立にH又はOHを表し、X4,X5は各々独立にH、OH又はCOOM3を表し、M1,M2,M3は各々独立にH、1価のアルカリ金属又はアンモニウムイオンを表し、a,b,cは各々独立に0又は1の整数を表す。ただし、式(1)において、X4とX5は同時にCOOM3となることはない。 - 陽極を備えた陽極室と陰極を備えた陰極室とをカチオン交換膜で隔離し、該陽極室にCoイオン及びFeイオンを含む液を導入し、該陰極室に下記式(1)で表されるジカルボン酸及びその塩並びにトリカルボン酸及びその塩から選ばれる1種以上の添加剤を含む液を導入し、該陽極と該陰極間に通電することにより、該陽極室内の液中のCoイオン及びFeイオンを該カチオン交換膜を透過させて該陰極室内の液中に移動させ、該陰極上にCo及びFeを析出させることを特徴とするCoとFeの電着方法。
M1OOC-(CHX1)a-(NH)b-(CX2X4)c-CX3X5-COOM2 …(1)
式(1)中、X1,X2,X3は各々独立にH又はOHを表し、X4,X5は各々独立にH、OH又はCOOM3を表し、M1,M2,M3は各々独立にH、1価のアルカリ金属又はアンモニウムイオンを表し、a,b,cは各々独立に0又は1の整数を表す。ただし、式(1)において、X4とX5は同時にCOOM3となることはない。 - 前記ジカルボン酸が、マロン酸、コハク酸、リンゴ酸、酒石酸及びイミノ二酢酸から選ばれる1種以上であることを特徴とする請求項9又は10に記載のCoとFeの電着方法。
- 前記トリカルボン酸が、クエン酸であることを特徴とする請求項9乃至11のいずれか1項に記載のCoとFeの電着方法。
- 前記添加剤を含む液が、アンモニウム塩を含むことを特徴とする請求項9乃至12のいずれか1項に記載のCoとFeの電着方法。
- 前記アンモニウム塩が塩化アンモニウム、硫酸アンモニウム及びシュウ酸アンモニウムから選ばれる1種以上であることを特徴とする請求項13に記載のCoとFeの電着方法。
- 前記トリカルボン酸が、クエン酸アンモニウムであることを特徴とする請求項13に記載のCoとFeの電着方法。
- Coイオン及びFeイオンと、下記式(1)で表されるジカルボン酸及びその塩並びにトリカルボン酸及びその塩から選ばれる1種以上の添加剤とを含む液を保持する電着槽と、該電着槽内の該液中に設けられた陽極及び陰極と、該陽極及び陰極間に通電する通電手段とを有し、該陽極及び陰極間に通電することにより、該陰極上にCo及びFeを析出させることを特徴とするCoとFeの電着装置。
M1OOC-(CHX1)a-(NH)b-(CX2X4)c-CX3X5-COOM2 …(1)
式(1)中、X1,X2,X3は各々独立にH又はOHを表し、X4,X5は各々独立にH、OH又はCOOM3を表し、M1,M2,M3は各々独立にH、1価のアルカリ金属又はアンモニウムイオンを表し、a,b,cは各々独立に0又は1の整数を表す。ただし、式(1)において、X4とX5は同時にCOOM3となることはない。 - 陽極を備えた陽極室と、陰極を備えた陰極室と、該陽極室と陰極室とを隔離するカチオン交換膜とを有する電着槽と、該陽極及び陰極間に通電する通電手段と、該陽極室にCoイオン及びFeイオンを含む液を通液する通液手段と、該陰極室に下記式(1)で表されるジカルボン酸及びその塩並びにトリカルボン酸及びその塩から選ばれる1種以上の添加剤を含む液を通液する通液手段とを有し、該陽極と該陰極間に通電することにより、該陽極室内の液中のCoイオン及びFeイオンを該カチオン交換膜を透過させて該陰極室内の液中に移動させ、該陰極上にCo及びFeを析出させることを特徴とするCoとFeの電着装置。
M1OOC-(CHX1)a-(NH)b-(CX2X4)c-CX3X5-COOM2 …(1)
式(1)中、X1,X2,X3は各々独立にH又はOHを表し、X4,X5は各々独立にH、OH又はCOOM3を表し、M1,M2,M3は各々独立にH、1価のアルカリ金属又はアンモニウムイオンを表し、a,b,cは各々独立に0又は1の整数を表す。ただし、式(1)において、X4とX5は同時にCOOM3となることはない。 - 前記ジカルボン酸が、マロン酸、コハク酸、リンゴ酸、酒石酸及びイミノ二酢酸から選ばれる1種以上であることを特徴とする請求項16又は17に記載のCoとFeの電着装置。
- 前記トリカルボン酸が、クエン酸であることを特徴とする請求項16乃至18のいずれか1項に記載のCoとFeの電着装置。
- 前記添加剤を含む液が、アンモニウム塩を含むことを特徴とする請求項16乃至19のいずれか1項に記載のCoとFeの電着装置。
- 前記アンモニウム塩が塩化アンモニウム、硫酸アンモニウム及びシュウ酸アンモニウムから選ばれる1種以上であることを特徴とする請求項20に記載のCoとFeの電着装置。
- 前記トリカルボン酸が、クエン酸アンモニウム塩であることを特徴とする請求項20に記載のCoとFeの電着装置。
- 放射性物質を吸着すると共に、酸化鉄を主成分とするクラッドを含む廃イオン交換樹脂に、60℃以上に加温した酸を接触させて、該廃イオン交換樹脂中のイオン状の放射性物質を溶離除去するとともに、該クラッドを溶解除去する除染工程を含むことを特徴とする放射性廃イオン交換樹脂の除染方法。
- 前記酸は、硫酸および/又はシュウ酸であることを特徴とする請求項23に記載の放射性廃イオン交換樹脂の除染方法。
- 前記酸は、5~40重量%の硫酸溶液および/又は0.1~40重量%のシュウ酸溶液であることを特徴とする請求項23又は24に記載の放射性廃イオン交換樹脂の除染方法。
- 前記放射性物質はコバルト-60を含むことを特徴とする請求項23乃至25のいずれか1項に記載の放射性廃イオン交換樹脂の除染方法。
- 前記除染工程から排出されるイオン状放射性物質を含む酸廃液を、陽極と陰極を有する電着槽に導入し、該陽極と陰極間に通電することにより、該酸廃液中のイオン状放射性物質を陰極上に電着させて、該酸廃液からイオン状放射性物質を除去する電着工程と、該電着工程で、該イオン状放射性物質を除去して得られた処理液を前記除染工程に循環して再利用する循環工程とを含むことを特徴とする請求項23乃至26のいずれか1項に記載の放射性廃イオン交換樹脂の除染方法。
- 前記電着槽は、陽極が設置された陽極室と、陰極が設置された陰極室とが、カチオン交換膜により隔てられており、前記酸廃液は該陽極室に導入され、該陽極と陰極間に通電することにより、該酸廃液中のイオン状放射性物質が該カチオン交換膜を透過して該陰極室に移動し、該陰極上に電着されることを特徴とする請求項27に記載の放射性廃イオン交換樹脂の除染方法。
- 前記陰極上に、コバルト-60と、前記クラッドの溶解物である鉄が電着されることを特徴とする請求項27又は28に記載の放射性廃イオン交換樹脂の除染方法。
- 放射性物質を吸着すると共に、酸化鉄を主成分とするクラッドを含む廃イオン交換樹脂に、60℃以上に加温した酸を接触させて、該廃イオン交換樹脂中のイオン状の放射性物質を溶離除去するとともに、該クラッドを溶解除去する除染手段を含む放射性廃イオン交換樹脂の除染装置であって、該除染手段は、前記廃イオン交換樹脂が充填される充填塔と、該充填塔に前記加温した酸を導入する導入配管と、該導入配管に設けられた加温手段と、該充填塔からイオン状放射性物質を含む酸廃液を排出する排出配管とを備えることを特徴とする放射性廃イオン交換樹脂の除染装置。
- 陽極と陰極を有する電着槽と、該陽極と陰極に通電する手段と、該電着槽に前記酸廃液を導入する手段と、該電着槽の処理液を前記加温手段の上流側に循環する手段とを有し、該陽極と陰極間に通電することにより、該酸廃液中のイオン状放射性物質を陰極上に電着させて、該酸廃液からイオン状放射性物質を除去し、該イオン状放射性物質を除去して得られた処理液が前記除染手段で再利用されることを特徴とする請求項30に記載の放射性廃イオン交換樹脂の除染装置。
- 前記電着槽は、陽極が設置された陽極室と、陰極が設置された陰極室と、該陽極室と陰極室とを隔離するカチオン交換膜とを有し、前記酸廃液は該陽極室に導入され、該陽極と陰極間に通電することにより、該酸廃液中のイオン状放射性物質が該カチオン交換膜を透過して該陰極室に移動し、該陰極上に電着されることを特徴とする請求項31に記載の放射性廃イオン交換樹脂の除染装置。
- 前記陰極上に、コバルト-60と、前記クラッドの溶解物である鉄が電着されることを特徴とする請求項31又は32に記載の放射性廃イオン交換樹脂の除染装置。
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