JPH1043710A - Method and device for treating waste containing metal oxide and material to be oxidized - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reproduce nitric acid in a catholyte in an electrolytic oxidation means and to keep the concentration by removing water. SOLUTION: Nitric acid is reproduced by supplying a nitric acid solution of the catholyte containing a reduction product of nitric acid and silver ion to a 1st electrolyte section 10 of an electrolytic dialysis concentrating means composed of 4 sections divided respectively by an anode 9 and a cation exchange membrane 8, the cation exchange membrane 8 and an anion exchange membrane 11, the anion exchange membrane 11 and a cation exchange membrane 13, the anion exchange membrane 13 and a cathode 15 to form a chemical species of silver in 2-valent state and at the same time, water is transferred to a 2nd electrolyte section 12 to generate nitric acid to use to dissolve a metal oxide. A sodium nitrate aq. solution is supplied in a 3rd lectrolyte section and a sodium hydroxide aq. solution is generated in a 4rd electrolyte section. Then, the reproduction and the concentration of nitric acid are simultaneously executed without producing a waste gas and a waste water with small power consumption.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating waste containing metal oxides and oxidizable materials, and more particularly to a metal oxide material constituting nuclear fuel material, fission products, incinerated ash and the like. TECHNICAL FIELD The present invention relates to a metal oxide and a waste treatment method including a oxidizable substance, which are suitable for the treatment of a waste substance containing an organic substance or an oxidizable substance at the same time as carbon, and a treatment apparatus therefor.

[0002]

2. Description of the Related Art JP-A-58-176133, "Method of Electrolytic Dissolution of Plutonium Dioxide and Neptunium Dioxide"
Is, Ce, Ag, allowed to exist at a certain concentration while playing electrolytically at least one oxidizing agent comprising a compound which is soluble in aqueous nitric acid solution consisting of Co or Am, PuO contained in PuO ₂ or a nuclear fuel ₂ / NpO ₂ is dissolved in an aqueous nitric acid solution and recovered.

[0003] KOKOKU 5-45000 discloses "plutonium recovery method of the solid waste" is contacted with nitric acid containing soluble Ag ²⁺ compound waste concentration at 2-8M, Ag ²⁺ Plutonium Is oxidized and dissolved in nitric acid. The contact between the waste and nitric acid is performed in an electrolytic cell including an anode and a cathode, and an electrode is applied with a potential for continuously generating Ag ²⁺ for oxidizing plutonium contained in the waste.

[0004] KOKOKU 5-45157 discloses "plutonium oxide and or dissolution method and dissolving apparatus oxide neptunium" is put PuO ₂ / NpO ₂ to be dissolved in a nitric acid solution of 2-8M, by adding AgO PuO ₂ / NpO ₂ is oxidized and dissolved. AgO / (PuO ₂ or Np
O ₂ ) ratio is 3.5-4. The device shall consist of two or more vertical tubes. It has two tubes for circulating the solid-liquid mixture between the first tube and the second tube.

Japanese Unexamined Patent Publication No. Sho 64-30689, "Waste Disposal Method and Apparatus" is particularly applicable to wastes based on organic matter, and is a primary oxidizing species in a nitric acid aqueous solution at about 50 ° C. Ag ²⁺ is electrochemically generated, and the waste is decomposed by the second oxidizing species generated by the interaction between the primary oxidizing species and the electrolytic solution. Ag ⁺ produced by the decomposition of waste is electrochemically regenerated to Ag ²⁺ .

M. Fleischmann, D. Precha, A. Raffinsky, The
Kinetics of the Silver (I) / Silver (II) Couple at a Platinum Electrode in Perchloric and Nitrick Acids, Journal of Applied Electrochemistry, Vol. 1, 1971, pp. 1-7 ( M. Fleischman, D. Pletcher, A. Rafinski, The kineti
cs of the silver (I) / silver (II) coupleat a plati
num electrode in perchloric and nitric acids, Jour
nal of Applied Electrochemistry, 1 (1971) 1-
7) is a silver species (Ag (II)) which is in a divalent state by electrolytic oxidation of a 3M aqueous solution of silver nitrate with a platinum electrode.
And the oxidation reaction between Ag (II) in the electrolytic solution and inorganic and organic substances in the electrolytic bath or in the external reaction solution. The conventional examples of regenerating the oxidizing agent by the above-described electrolysis (described in each gazette) are based on the cited document (1), which is a known example, regardless of whether or not cited.

[0007] Only the invention described in JP-A-64-30689 requires a large amount of oxidizing agent to be regenerated by electrolysis in order to oxidatively decompose organic-based waste in the anode chamber of the electrolytic cell. This provides a means for regenerating the catholyte solution, which will contain nitrous oxide and nitrogen oxides in the cathodic compartment and reduce the concentration of nitric acid. For this reason, the invention described in this publication has a configuration in which the aqueous solution is heated to regenerate the aqueous solution, is caused to flow down the packed tower, and a gas containing oxygen is blown. A nitric acid solution containing nitrous acid and an oxide of nitrogen and a gas containing steam and oxygen generated by heating the solution are brought into contact in a packed column to regenerate nitric acid and an oxide of nitrogen into nitric acid.

[0008]

The silver species in a divalent oxidation state are brought into contact with each other while being electrochemically regenerated.
In the method of oxidatively decomposing waste containing oxidizable substances, not only when the waste is based on organic substances, but generally when oxidizable substances are contained, a large amount of divalent oxidation state in the electrolytic cell It is necessary to regenerate the silver species at which the anodic reaction has a formal potential as follows: The lower the Ag ⁺ concentration and the higher the potential of the anode, the more easily the second-stage reaction occurs.

Ag ⁺ = Ag ²⁺ + e 1.98 V H ₂ O = １ ／ O ₂ + 2H ⁺ + 2e 1.70 V In the anolyte, the following is performed between Ag ²⁺ and a nitric acid aqueous solution as a solvent. In the anolyte compartment, the electrochemical reaction decomposes water into oxygen and hydrogen ions, and transfers hydrogen ions to the catholyte compartment.

HNO ₃ + Ag ²⁺ = AgNO ₃ ⁺ + H ⁺² AgNO ₃ ⁺ + H ₂ O = ₂ Ag ⁺ + 1 / 2O ₂ + 2H ⁺ +2
NO ₃ ~ In response to the reaction in the anolyte, the following reaction in the catholyte depends on the concentration of hydrogen ions and the cathode potential, the concentration of hydrogen ions is low, and the potential of the cathode is low The lower reaction takes place.

[0011] ^{_{NO 3 ~ + 5H + + 4e}} = 1 / 2N 2 O + 5 / 2H 2 O 1.11V NO 2 ~ + 2H + + e = NO + H 2 O 0.98V NO 3 ~ + 4H + + 3e = NO + 2H 2 O 0.96V NO 3 ~ + 3H ⁺ + 2e = HNO ₂ + H ₂ O 0.93V NO ₃ ~ + 8H ⁺ + 6e = NH ₄ ⁺ + 2H ₂ O 0.86V 2NO ₃ ~ + 4H ⁺ + 2e = N ₂ O ₄ + 2H ₂ O 0.80V Ag ⁺ + e = conventional methods in ^{Ag 0.80V H + + e = 1} / 2H 2 0.00V Sho 64-30689 discloses is to play the oxide nitrite and nitrogen in nitric acid. Since the reaction occurring at this time is a reverse reaction of the above-described reaction in the cathode chamber liquid, it is possible to regenerate nitric acid and simultaneously consume water to regenerate a highly concentrated nitric acid solution. However, in the catholyte solution, if the substance that carries charges from the anode is H ₃ O ⁺ ions, one molecule of water is increasing due to the transfer of one Faraday's charge, and the charge is changed to another metal element. It is known that a greater amount of water will increase if transported with cations. The conventional method disclosed in JP-A-64-30689 removes only water molecules involved in the regeneration of nitric acid. Therefore, there is a problem that water in the cathode compartment liquid increases and the nitric acid concentration decreases during operation of the electrolytic cell. Was.

An object of the present invention is to regenerate nitric acid and nitrogen oxides in a nitric acid aqueous solution, which is a catholyte solution of an electrolytic oxidizing means, for generating and regenerating divalent silver species in a valence state. At the same time, the water in the nitric acid aqueous solution, which is the catholyte solution, can be removed to keep the nitric acid concentration in the catholyte solution high.
An object of the present invention is to provide a method for treating waste containing a metal oxide and an oxidizable substance.

Another object of the present invention is to provide a method for converting a metal oxide, which is an oxidizable substance, into a nitrate without reducing nitric acid to nitric oxide in the anode chamber liquid of the electrolytic oxidizing means. It is an object of the present invention to provide a method for treating waste containing waste and oxidizable substances.

Another object of the present invention is to provide a metal oxide and a metal oxide which can be almost entirely regenerated to nitric acid without releasing nitric oxide as a gas from a nitric acid aqueous solution which is a catholyte solution of the electrolytic oxidizing means. An object of the present invention is to provide a method for treating waste containing an oxidizing substance. Another object of the present invention is to regenerate the catholyte solution of the electrolytic oxidizing means into nitric acid, and convert the catholyte solution containing metal ions generated by the electrolytic dialysis concentrating means in the course of concentration to a catholyte solution of the electrolytic oxidizing means. Wastewater containing a metal oxide and an oxidizable substance, which can be supplied to an anolyte chamber via a chamber and supply nitric acid for converting a metal oxide into a nitrate in the anolyte chamber. And an apparatus therefor.

Another object of the present invention is to recover sodium hydroxide produced in the fourth electrolytic solution chamber of the electrolytic dialysis concentrating means, neutralize it by mixing it with nitric acid, and convert the electrolytic dialysis condensate into an aqueous sodium nitrate solution. It is an object of the present invention to provide a method and an apparatus for treating waste containing metal oxides and oxidizable substances, which can be supplied to a third electrolytic solution chamber.

Another object of the present invention is to provide an electrodialysis and desalting means, wherein sodium nitrate diluted in a third electrolytic solution chamber of the electrolytic dialysis concentrating means is converted into a concentrated liquid and a diluting liquid by an electrodialysis desalting means, and By refluxing into the liquid chamber and discharging the diluent, the amount of sodium nitrate to be discharged can be significantly reduced and at the same time the power consumption of the electrodialysis concentrating means can be reduced. It is an object of the present invention to provide a method and apparatus for treating waste containing waste.

Another object of the present invention is to provide a method and apparatus for treating waste containing metal oxides and oxidizable substances, which does not generate flammable hydrogen gas and consumes little energy. It is in.

[0018]

The feature of the present invention, which achieves the above object, is that the electrolytic oxidizing means contains nitrous acid and nitrogen oxides and silver or other metal ions, and the content of water is increased. The catholyte solution, which is an aqueous nitric acid solution, is supplied to the anode of the electrolytic dialysis concentrating means and the first electrolyte solution compartment defined by the first cation exchange membrane. Oxidize the material to recover nitric acid,
Further, since water is removed along with the hydrogen ions through the first cation exchange membrane, the aqueous nitric acid solution is concentrated.

A feature of the second aspect of the present invention that achieves the above object is to perform oxidative dissolution of a metal oxide composed of an oxidizable substance with nitric acid in the presence of a silver species in a divalent valence state. Another object of the present invention is to prevent the generation of nitric oxide, which is a reduction product of nitric acid.

In order to achieve the above object, a feature of the present invention is that the reduced product of nitric acid is transferred from the circulating liquid tank of the electrolytic oxidation means into which the catholyte solution flows into the first electrolytic solution chamber of the electrolytic dialysis concentrating means. The aqueous nitric acid solution is supplied, and the catholyte solution flowing out of the cathode chamber of the electrolytic oxidizing means is directly supplied to the first electrolytic solution chamber of the electrodialysis / concentrating means without mixing with the aqueous nitric acid solution in the circulation tank, By supplying a larger amount of electricity than the amount of electricity consumed in the reduction of the aqueous nitric acid solution in the cathode chamber of the electrolytic oxidizing means in the first electrolytic solution chamber of the electrolytic dialysis concentrating means, the first electrolytic chamber of the electrolytic dialytic concentrating means is provided. The purpose of the present invention is to supply an aqueous nitric acid solution from which nitric acid has been regenerated and water has been removed from the circulating liquid tank into which the liquid flows, into the catholyte chamber of the electrolytic oxidation means.

A feature of the invention according to claim 4 which achieves the above object relates to the solubility of nitric oxide, which is a reduction product of nitric acid, in water, wherein the concentration of nitrogen oxide in the catholyte of the electrolytic oxidizing means is 5 minutes of the solubility. By controlling the amount of electrolytic electricity and the amount of liquid supplied to the cathode chamber in association with each other so as to be 1 or less, the rate of regeneration of nitric oxide to nitric acid is increased to 80% or more, and the regeneration of nitric acid reduction products to nitric acid is performed. The rate is to be at least 80% or more.

A feature of the invention of claim 5 that achieves the above object is that, in the first electrolytic solution chamber of the electrolytic dialysis concentrating means, a silver species in a divalent valence state is generated, and the oxidizing power of the species is generated. Another object of the present invention is to reduce the amount of electricity consumed by the electrolytic dialysis concentrating means by causing a reduction product of nitric acid in an electrolytic solution to occur not only in an oxidation reaction due to contact with an electrode but also in a liquid phase. A feature of the invention of claim 6 that achieves the above object is that silver is in a divalent valence state from supplying the effluent of the first electrolyte chamber to the catholyte chamber of the electrolytic oxidizing means and flowing out. A sufficient amount of silver species in the divalent valence state for the presence of the species is generated in the first electrolyte chamber of the electrodialysis concentrating means, so that the silver species in the catholyte chamber of the electrolytic oxidation means are generated. The object is to prevent the generation of nitric acid reduction products.

According to a seventh aspect of the present invention which achieves the above object, the concentration of nitric acid in the second electrolytic solution of the electrolytic dialysis concentrating means can reach 10M, and the concentration of the first nitric acid in the first electrolytic solution can be increased. The anolyte circulates through the cation exchange membrane through the catholyte circulation tank of the electrolytic oxidizing means, wherein the second electrolytic chamber solution adjusted to a nitric acid concentration of 10 M or less based on the presence of metal ions. It is to supply to a tank for dissolving a metal oxide and producing a nitrate solution of a metal.

[0024] A feature of the invention of claim 8 that achieves the above object is that it is produced in a fourth electrolyte chamber of the electrolytic dialysis concentrating means.
An aqueous sodium hydroxide solution having a concentration of 10 M or less is collected, neutralized with nitric acid to generate an aqueous sodium nitrate solution, and supplied to the third electrolytic solution chamber of the electrodialysis / concentration means.

According to a ninth aspect of the present invention which achieves the above object, an electrolytic solution having a reduced sodium nitrate concentration in the third electrolytic solution chamber of the electrolytic dialysis concentrating means is treated by an electrodialysis desalting means, and the concentrated liquid is removed. Refluxing into the third electrolyte chamber and discharging the diluent.

The features of the present invention according to claims 10 and 11 for achieving the above object are apparatuses for embodying the features of the invention according to claims 1 to 9.

A feature of the twelfth aspect of the present invention that achieves the above object is that the fourth electrolytic solution chamber of the electrolytic dialysis concentrating means comprises:
An object of the present invention is to prevent generation of hydrogen during electrolysis by using an electrode that transmits air as a cathode.

The first aspect of the present invention is to provide nitric acid, nitrogen oxide and water, which are reduction products of nitric acid electrochemically generated in the catholyte compartment of the electrolytic oxidizing means, in one of the electrolytic solution chambers of the electrolytic dialysis concentrating means. Among them, it has an effect of electrochemically oxidizing and bonding to regenerate nitric acid and further removing water by electrochemical action.

A specific example of the first aspect of the present invention will be described below.

The steady electrochemical reaction that takes place using platinum as the anode in the anolyte compartment of the electrolytic oxidizing means is the generation of silver species in a divalent oxidation state, the concentration of nitric acid, the concentration of silver ions, Dependent on the current density (anodic potential) is accompanied by the production of oxygen. The electrochemical reaction that takes place using platinum as the cathode in the catholyte compartment of the electrolytic oxidation means depends on the nitric acid concentration and the current density (cathode potential), and the product is more complicated. However, when the electrolytic nitric acid concentration of the electrolytic oxidizing means is 4 M to 8 M, the current density is 0.1 A / cm ^{2 to} 0.5 A / cm ^2.
It has been empirically known that 70% of the reduced nitric acid molecules would be nitric oxide (NO). If the remainder were to be nitrous acid (HNO ₂ ), 1.7 grams of water would be produced with the reduction reaction. In this case, 2.7 Faraday of electricity is required for reducing 1 gram molecule of nitric acid. In order for 2.7 Faraday's quantity of electricity to flow between the electrodes, 2.7 grams of molecular hydrogen ions need to carry charge, and 2.7 grams of water move from the anolyte compartment to the catholyte compartment. . Therefore, if one gram molecule of nitric acid (63 g) is reduced and lost in the catholyte compartment, a total of 4.4 gram molecules (79.2 g) of water will increase, and as the electrolysis proceeds. The nitric acid concentration will decrease rapidly. When the concentration of nitric acid decreases, a reaction having a low oxidation-reduction potential occurs, so that the electrolytic voltage of the electrolytic oxidation means increases, and unsafe substances such as ammonia and hydrogen are generated in the catholyte compartment.

When the catholyte solution of the electrolytic oxidizing means is supplied to the first electrolytic solution chamber of the electrolytic dialysis concentrating means in which a potential difference equal to or higher than the oxidation-reduction potential of nitrogen monoxide (0.96 V) is applied to the anode, Then, nitric oxide and nitrous acid are oxidized to nitric acid, and if the oxidation efficiency is ideal, one gram molecule (63 g) of nitric acid is generated for every 2.7 Faraday electricity, and 1.7 gram molecule of water is generated. (30.6 g). As a result of the electrodialysis, 2.7 g molecules of water (48.6 g) move from the first electrolyte chamber to the second electrolyte chamber, and consequently, 1 g molecule of nitric acid in the first electrolyte chamber. Each time is produced, 4.4 grams of molecules (79.2 g) of water are lost and the aqueous nitric acid solution will increase in concentration.

According to the second aspect of the present invention, not only is the formation of a salt by combining with nitric acid to lower the concentration, but also the reduction of the concentration of nitric acid by reducing nitric acid to produce a nitrogen oxide. In connection with the decomposition treatment, waste is added to a nitric acid aqueous solution containing a silver species (Ag (II)) in a divalent valence state, and nitrogen oxides are not generated while regenerating Ag (II) by electrolysis. And has an operation effect based on the operation of extracting the treatment liquid containing nitrate.

A specific example of the second aspect of the present invention will be described below.

Compounds of the element that can have higher valence states tend to be oxidized by nitric acid to compounds of higher valence state elements, and nitric acid tends to be reduced to lower valence state compounds of nitrogen. This reaction has a high nitric acid concentration,
The higher the temperature, the faster it progresses. On the other hand, many metal oxides combine with nitric acid to form nitrate and water, and dissolve in water. In order to achieve the purpose of dissolving metal oxides in nitric acid and separating them from waste to treat them, the reduction of nitric acid and the loss as nitric oxide not only increases the amount of nitric acid used but also It is necessary to remove nitric oxide from exhaust gas.

According to a second aspect of the present invention, waste containing an oxidizable substance is added to an aqueous nitric acid solution containing silver species in a divalent state, which is carried out in an anolyte circulation tank of electrolytic oxidation means. Then, oxidation of the oxidizable substance is performed by silver species in a divalent valence state, and nitric acid is consumed only for nitrate generation. An embodiment of the present invention provides a batch feed of waste containing metal oxides and oxidizable materials, regeneration by electrolysis of silver species in a divalent state, and silver nitrate and other metal nitrates. It is preferable that the extraction of the aqueous nitric acid solution containing and the replenishment of the aqueous nitric acid solution containing silver nitrate commensurate with the extraction are performed continuously.

According to a third aspect of the present invention, the catholyte is supplied to the first electrolytic solution chamber of the electrodialyzing and concentrating means by preventing the reduction product of nitric acid generated in the catholyte chamber of the electrolytic oxidation means from accumulating in the catholyte. By this time, it has the effect of preventing the transfer of nitric oxide among the reduction products of nitric acid to the gas phase.

A specific example of the third aspect of the present invention will be described below.

As described above, the electrolytic reduction product of nitric acid is 7%.
It is believed that 0% is nitric oxide and 30% is nitrous acid. Nitric oxide can be added at room temperature to about 5
Dissolve 0 ml / l (2.2 mM). At atmospheric pressure, if the concentration of nitric oxide in water is 50 ml / l (2.2 mM), it will be released into the gas phase. Nitrite decomposes into nitric oxide and nitrogen dioxide by a heterogeneous reaction when the concentration increases,
Nitrogen dioxide is dissolved again in water to produce nitric acid and nitrous acid, but nitric oxide is released into the gas phase. When a nitric acid aqueous solution containing nitric oxide is supplied to the first electrolytic solution chamber of the electrolytic dialysis concentrating means, and nitric oxide dissolved in the nitric acid aqueous solution is oxidized to nitric acid, and the concentration of nitric oxide decreases, Nitric oxide in the gas phase can partially dissolve and contribute to the oxidation reaction, but nitric oxide remaining in the gas phase cannot be oxidized electrochemically.

According to a third aspect of the present invention, the nitric acid aqueous solution containing nitric oxide and nitrous acid which has flowed out of the catholyte compartment of the electrolytic oxidizing means is not returned to the catholyte circulation tank, but the first electrolytic dialysis concentrating means is used. It is supplied to the electrolyte circulation tank,
This is achieved by supplying a nitric acid aqueous solution having a reduced concentration of nitric oxide and nitrous acid flowing out of the electrolytic solution chamber to the catholyte circulation tank. Furthermore, the amount of electricity loaded in the first electrolytic solution chamber of the electrolytic dialysis concentrating means is sufficiently larger than the amount of electricity consumed to reduce nitric acid in the catholyte compartment of the electrolytic oxidation means,
Since the aqueous nitric acid solution supplied to the catholyte compartment of the electrolytic oxidizing means contains no reduction product of nitric acid, the amount of nitric oxide that cannot be oxidized can be reduced.

According to a fourth aspect of the present invention, the concentration of nitric oxide dissolved in the aqueous nitric acid solution flowing out of the catholyte compartment of the electrolytic oxidizing means and supplied to the first electrolytic compartment of the electrolytic dialysis concentrating means is kept low. Thus, it has an effect of oxidizing as much as possible without regenerating nitric oxide into the gaseous phase and regenerating it into nitric acid.

A specific example of the fourth aspect of the present invention will be described below.

One atmosphere of nitric oxide is added to water 1 at room temperature by approximately 50
Dissolve ml / l (2.2 mM). At atmospheric pressure, if the concentration of nitric oxide in water is 50 ml / l (0.22 mM), 50% of the generated nitric oxide will remain in water in an equilibrium state and become 50%. As mentioned above, it consumes 2.7 Faraday's electricity and reduces 1 gram molecule of nitric acid to produce 0.7 gram molecule of nitric oxide.
In order to produce 0.045 milligrams of nitric oxide, 0.0017 Faraday of electricity is consumed,
It corresponds to 4.65 mAh / l. Therefore, when a current of 1 A flows through the electrolytic oxidizing means, in order for the concentration of nitric oxide to be 0.045 mM or less at the liquid outlet of the catholyte chamber, the catholyte outflow amount is 215 l / h ( 3.6 l / m
in) or more is required. In this case, the concentration of nitrous acid is 0.019 mM.

Similarly, if the concentration of nitric oxide in water at atmospheric pressure is 10 ml / l (0.45 mM), 80% of the produced nitric oxide will remain in water in an equilibrium state. When a current of 1 A flows through the electrolytic oxidation means, the concentration of nitric oxide is 0.45 at the liquid outlet of the catholyte compartment.
mM, the outflow of catholyte is 21.5 l
/ H (0.36 l / min) or more is required. In this case, the concentration of nitrous acid is 0.19 mM.

The invention of claim 5 relates to a method for increasing the efficiency of the oxidation reaction of the reduction product of nitric acid in the electrolytic dialysis concentrating means, wherein silver ions added to the anolyte of the electrolytic oxidizing means accompany electrolysis. The liquid has a function and an effect based on a phenomenon in which silver ions are contained in the catholyte by moving to the catholyte compartment.

A specific example of the fifth aspect of the present invention will be described below.

When the silver ion concentration in the anolyte of the electrolytic oxidizing means was kept at 0.1 M, 1.5 milligrams of silver ions were converted from the anolyte to the catholyte by electrolytic oxidation using 1 Faraday of electricity. moved. When the concentration of metal ions other than silver in the anolyte was 0.5 M, 7.5 milligrams of metal ions were transferred from the anolyte to the catholyte by an amount of electricity of 1 Faraday. In this case, empirically, the amount of water transferred from the anolyte to the catholyte was 2.6 g molecule (46.8 g) per 1 Faraday quantity of electricity. Therefore,
The silver ion concentration in the water that migrates from the anolyte to the catholyte is 3
When the operation of the electrolytic oxidizing means is continued, the silver ion concentration in the catholyte increases, but does not exceed 30 mM. When the electrodialysis / concentration means is operated, a larger amount of water is removed from the aqueous nitric acid solution in the first electrolytic solution chamber than the water that increases in the catholyte compartment of the electrolytic oxidation means, but the removed water is converted into the second electrolytic solution. This is because it is included and returned to the catholyte. Metal ions other than silver contained in the anolyte of the electrolytic oxidizing means also move to the catholyte and increase depending on the concentration in the anolyte.

The nitric acid aqueous solution supplied to the first electrolytic solution chamber of the electrolytic dialysis concentrating means contains silver ions along with nitrous acid, nitrogen oxides, etc., and the concentration of silver ions is reduced to the concentration of nitric acid reduction products. Higher, and if the potential of the anode is sufficiently high, the silver ions will be in a divalent valence state on the anode (Ag
(II)). Ag diffused away from the electrode
(II) reacts rapidly with the reduction product of nitric acid to regenerate nitric acid and return to Ag ⁺ . Since silver ions act catalytically and proceed not only on the electrode but also in the electrolytic solution, the regeneration efficiency of nitric acid by oxidation of reduction products of nitric acid is significantly increased, and the concentration of nitric oxide in the aqueous nitric acid solution is reduced. Thus, nitric oxide in the gas phase dissolves in the aqueous nitric acid solution, and the amount of nitric oxide released without being oxidized decreases.

The invention of claim 6 relates to a method for suppressing the generation of nitric acid reduction products in the catholyte compartment of the electrolytic oxidizing means and for regenerating nitric acid more effectively. Ag (I)
It is based on increasing the amount of Ag (II) generated in the first electrolytic solution chamber of the electrodialysis concentrating means so that I) remains.

A specific example of the invention according to claim 6 will be described below.

Although Ag (II) reacts with water and is reduced to Ag ⁺ in an aqueous nitric acid solution even when no oxidizable substance is present, the reaction rate is proportional to the square of the Ag (II) concentration. , Ag ⁺
It is known that the concentration is inversely proportional to the square of the hydrogen ion concentration. Therefore, it is impossible to convert all Ag ⁺ present in the nitric acid aqueous solution to Ag (II). According to Reference (1), nitric acid is 3M and the Ag ⁺ concentration is 0.1%.
The limit of the Ag (II) concentration that can be generated with a realistic current efficiency (60%) by electrolytic oxidation
About 40% of the g ⁺ concentration.

In the catholyte compartment of the electrolytic oxidizing means, an equivalent amount of A is equivalent to the reduction product of nitric acid generated when Ag (II) is not present.
In addition to g (II), it reacts with the aqueous nitric acid solution from the first electrolytic solution chamber of the electrolytic dialysis concentrating means to the catholyte chamber of the electrolytic oxidizing means via the circulating liquid tank and flows out of the catholyte chamber. If the amount of Ag (II) is generated at least in excess of the amount that disappears, Ag (II) will be contained in the aqueous nitric acid solution flowing out of the catholyte compartment.

Ag supplied to the catholyte compartment of the electrolytic oxidation means
Part of (II) exchanges electrons with the cathode and contributes to the flow of electric charge, suppresses the reduction reaction of nitric acid, and is reduced to Ag ⁺ , and part of the reduction of nitric acid partially generated in the catholyte It reacts directly with the substance and oxidizes, regenerating nitric acid and reducing it to Ag ⁺ .
The oxidation reaction rate of nitrous acid and nitric oxide in aqueous solution by Ag (II) is very high, and the concentration of nitrous acid and nitric oxide becomes negligibly small as long as Ag (II) remains.

When 0.36 liter of the electrolytic solution flows per ampere of the current flowing through the cathode of the electrolytic oxidizing means, the concentration of nitric oxide generated in the catholyte compartment is 0.56 m
M and nitrite was 0.19 mM, so Ag
The equivalent concentration of (II) is 2.1 mM. Ag (II) contained in the aqueous nitric acid solution supplied to the catholyte compartment of the electrolytic oxidation means
If the concentration of is not less than 2.1 mM, not only nitrous acid but also nitric oxide will not be produced in the catholyte compartment of the electrolytic oxidation means. If the concentration of Ag (II) can be increased, the flow rate of the catholyte can be reduced.

[0054] limiting current density when Ag ⁺ is electrochemically oxidized on the electrode Ag (II) is proportional to the Ag ⁺ concentration. When electrolysis is performed at a current density exceeding the limit current density, the amount of electricity consumed for oxygen generation increases and current efficiency decreases.
To generate Ag (II) with a constant current efficiency, Ag ⁺
If the concentration is low, it is necessary to increase the electrode area and electrolytic oxidation at a low current density. In order to keep the anode area of the electrolytic dialysis concentrating means within a practical range, the Ag in the first electrolytic solution is required.
It is desirable that the ⁺ concentration be higher than 20 mM.

The invention of claim 7 relates to the nitric acid aqueous solution generated in the second electrolytic solution chamber of the electrolytic dialysis concentrating means.
This is based on the presence of nitrate ions that migrate from the electrolyte through the anion exchange membrane to the second electrolyte and metal ions that migrate from the first electrolyte through the first cation exchange membrane to the second electrolyte.

A specific example of the seventh aspect of the present invention will be described below.

When the concentration of the aqueous solution of sodium nitrate in the third electrolytic solution chamber of the electrodialyzing / concentrating means is 1M, 1 gram molecule of nitric acid migrates from the third electrolytic solution chamber through the anion exchange membrane to the second electrolytic solution chamber. It is known that 1.5 grams of water migrates with the ions, and 2.2 grams of water migrates from the first electrolyte chamber to the second electrolyte chamber without metal ions. If 0.18M metal ions are contained in the catholyte of the electrolytic oxidizing means supplied to the first electrolytic solution chamber, 1 gram is transferred from the third electrolytic solution chamber to the second electrolytic solution chamber through an anion exchange membrane. 3.0 milligram molecules of metal ions and 3.1 grams of water (55.8 g) migrated from the first electrolyte chamber to the second electrolyte chamber along with the molecular nitrate ions.
As a result, the aqueous nitric acid solution generated in the second electrolyte chamber contains 1 gram molecule (63.0 g) of nitric acid and 4.6 gram molecule of water (82.
8g), with a volume of 115.2 ml and a concentration of 8.6 M
Was 43.2%, which corresponds to Metal ion concentration is 54
mM. The production of the aqueous nitric acid solution in the second electrolytic solution chamber contains at least 0.45 gram molecule of nitric acid per Faraday of electricity consumed by the electrolytic oxidizing means, and has a volume of 51.8 ml.

Assuming that the waste contains an oxidizable substance corresponding to one gram molecule of electron exchange and a metal oxide which forms a salt with one gram molecule of nitrate ion, the oxidizable substance is oxidized by electrolytic oxidation means. If one Faraday of electricity is required to oxidize the toxic material, one gram molecule of nitric acid is additionally required to convert the metal oxide to nitrate.

According to the third aspect of the present invention, the amount of electricity required by the electrolytic dialysis concentrating means is at least 2 Faraday for one Faraday of the amount of electricity required by the electrolytic oxidizing means. Is at least 1.7 Faraday. In the electrodialysis / concentration means according to the invention of claim 7, the amount of nitric acid newly generated per 1 Faraday of electricity is 0.45 g molecule. Thus, when one Faraday of electricity is consumed by the electrolytic oxidation means, the amount of nitric acid newly generated by the electrolytic dialysis concentration means is at least 0.8 to 0.9 gram molecules.

In the invention of claim 7, the aqueous nitric acid solution newly generated in the second electrolytic solution chamber of the electrolytic dialysis concentrating means is supplied to the catholyte circulation tank of the electrolytic oxidation means, and the overflow of the catholyte circulation tank is: If necessary, it is mixed with a specific amount of a nitric acid aqueous solution having a specific concentration and supplied to an anolyte circulation tank, and the overflow liquid in the anolyte circulation tank is discharged to a specific treatment step. By this operation, even if the treatment of the waste containing the metal oxidizing substance and the oxidizable substance is continuously performed, the nitric acid concentration and the metal ion concentration in the anolyte and the catholyte of the electrolytic oxidizing means are constant and required. Maintained at a sufficient level.

[0061] The invention of claim 8 relates to a characteristic operation management method of the third electrolyte chamber and the fourth electrolyte chamber of the electrodialysis concentrating means.

A specific example of the eighth aspect of the present invention will be described below.

The number of water molecules passing through the cation exchange membrane, which separates the third electrolytic solution chamber and the fourth electrolytic solution chamber of the electrolytic dialysis concentrating means, along with Na ions, depends on the concentration of sodium nitrate in the third electrolytic solution chamber. Change in a different way. If the concentration of sodium nitrate in the third electrolyte chamber is maintained at 0.5 to 1.0M,
For every gram molecule of Na ion, 5 gram molecules of water increase in the fourth electrolyte chamber, so that the fourth electrolyte has a concentration of 10
It becomes 30.8% sodium hydroxide aqueous solution corresponding to M.
This aqueous sodium hydroxide solution can be neutralized with nitric acid to obtain an aqueous sodium nitrate solution, which can be supplied to the third electrolytic solution chamber of the electrodialysis and concentration means. The higher the concentration of sodium nitrate supplied to the third electrolytic solution chamber of the electrodialyzing / concentrating means, the smaller the amount of sodium nitrate aqueous solution overflowing from the circulating tank for the third electrolytic solution and the smaller the amount of sodium nitrate released, Desirable for mass balance. If the concentration of nitric acid for neutralizing a 10 M aqueous sodium hydroxide solution, which is the fourth electrolytic solution of the electrodialysis / concentration means, is 6.0 M or more, the concentration of the aqueous sodium nitrate solution becomes 3.5 M or more. is there.

The lower the concentration of sodium nitrate in the third electrolytic solution of the electrodialyzing / concentrating means, the lower the amount of sodium nitrate released. However, the electric resistance of the third electrolytic solution chamber is proportional to the concentration of sodium nitrate. Even when the sodium concentration is 1M, it occupies about 15% of the entire resistance of the electrodialysis / concentration means, and when the concentration becomes 0.5M, the total electric resistance increases by 15%. It is not desirable from the viewpoint of reducing the power consumed for driving.

According to a ninth aspect of the present invention, sodium nitrate discharged from the third electrolytic solution chamber of the electrolytic dialysis concentrating means is recovered and refluxed to the third electrolytic solution chamber to reduce the amount of sodium nitrate discharged to the outside. And using known electrodialysis means.

A specific example of the ninth aspect of the present invention will be described below.

By alternately arranging a plurality of cation exchange membranes and a plurality of anion exchange membranes, a known electrodialysis means in which a diluent chamber and a concentrate chamber are alternately arranged is used. Supplied a 1 M aqueous solution of sodium nitrate, performed electrodialysis, and adjusted the concentration of sodium nitrate in the diluent to 0.1 M.
And making the concentration of sodium nitrate in the concentrate at least 3.5 M is possible at a current efficiency of 80% or more.

When the concentration of sodium nitrate in the third electrolytic solution of the electrodialysis / concentration means is reduced to 0.1 M, the power consumption of the electrodialysis / concentration means increases to 229%. On the other hand, while the sodium nitrate concentration of the third electrolytic solution of the electrodialysis / concentration means is maintained at 1M and the sodium nitrate concentration of the discharged water is reduced to 0.1M by the electrodialysis means, the electric energy required for the electrodialysis / concentration is Only 10% of the power consumption of the vehicle.

A tenth aspect of the present invention is a metal oxide which embodies the first, second, third, fourth, fifth, seventh, eighth, and ninth aspects of the present invention. And a waste treatment device containing oxidizable substances.

According to the eleventh aspect of the present invention, there is provided a method for treating a waste containing a metal oxide and an oxidizable substance according to the first, second, sixth, seventh and ninth aspects of the present invention. Device. A twelfth aspect of the present invention is to supply air by using the cathode of the electrolytic dialysis concentrating means as a gas diffusible electrode. The effects of the invention of claim 11 have the effects of claims 1 to 10 and do not generate hydrogen in the fourth electrolytic solution which is an aqueous sodium hydroxide solution, so that the risk is reduced and at the same time the electrodialysis is performed. The energy consumption of the concentration means is reduced.

Specifically, instead of a plate-like cathode such as platinum, an electrode material in which platinum is adhered to a porous carbon fiber material is bonded to an electrode holding material made of a wire mesh such as silver or nickel to form an electrode. By bringing one surface of the electrode to which negative electrolysis is loaded into contact with the electrolytic solution and the other surface into contact with air or oxygen, oxygen diffuses inside the electrode and combines with hydrogen at the contact surface with the electrolytic solution to form water. And does not generate hydrogen gas. Since the energy consumption for generating hydrogen from the platinum cathode is reduced, the potential difference between the electrodes of the electrolytic cell, which depends on the load current density, is reduced.

[0072]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) An apparatus for treating waste containing a metal oxide and an oxidizable substance according to a preferred embodiment of the present invention will be described below with reference to FIG.

This embodiment has an electrolytic oxidation means 1 and an electrolytic dialysis concentration means 2. The electrolytic oxidation means 1 has an anolyte compartment 4 and a catholyte compartment 5 separated by a diaphragm 3. Anolyte compartment 4
The anode 6 installed inside is made of platinum-plated titanium. The cathode 7 provided in the catholyte compartment 5 is made of platinum-plated titanium.

The electrolytic dialysis concentrating means 2 comprises a first electrolytic solution chamber 10 partitioned by an anode 8 made of platinum-plated titanium and a first cation exchange membrane 9, and an anion exchange membrane. The second electrolyte chamber 12 divided by the membrane 11, the third electrolyte chamber 12 divided by the anion exchange membrane 11 and the second cation exchange membrane 13
It has an electrolyte solution chamber 14, a second cation exchange membrane 13, and a fourth electrolyte solution chamber 16 defined by a cathode 15 made of platinum-plated titanium. The first cation exchange membrane 9 is a perfluorosulfonate-based strongly acidic type, the anion exchange membrane 11 is a strongly basic type with low hydrogen ion diffusion, and the second cation exchange membrane 13 is a first cation exchange membrane 13. It is the same material as the ion exchange membrane.

In this embodiment, the catholyte supplied from the catholyte circulation tank 17 to the catholyte chamber 5 by the pipe 18 does not return to the catholyte circulation tank 17 but is transferred to the first electrolyte circulation tank 20 by the pipe 19. The first electrolyte chamber 2 by the pipe 21
And circulates at a constant flow rate to the catholyte circulation tank 17 via the pipe 22. Therefore, all the catholyte flowing out of the catholyte compartment 5 passes through the first electrolyte compartment 10 and is circulated to the catholyte circulation tank 17 via the pipe 22. First
An overflow solution discharge pipe 23 is connected to the electrolyte solution chamber 20, and the overflow solution is supplied to the catholyte circulation tank 17. Catholyte circulation tank 17
Is connected to an oxygen discharge pipe 24, and the first electrolyte circulation tank 20
Is connected to a nitric oxide discharge pipe 25. Catholyte circulation tank 1
An overflow liquid extraction pipe 26 is connected to 7, and the overflow liquid is mixed with a nitric acid aqueous solution supplied from a nitric acid aqueous solution supply pipe 27 and supplied to an anolyte circulation tank 28. The anolyte circulates through the anolyte circulation tank 28, the pipe 29, the anolyte chamber 4, and the pipe 30 at a constant flow rate. An oxygen discharge pipe 31 and an overflow liquid discharge pipe 32 are connected to the anolyte circulation tank 28.

The second electrolytic solution, which is an aqueous solution of nitric acid, circulates through the second electrolytic solution circulating tank 33, the pipe 34, the second electrolytic solution chamber 12, and the pipe 35 at a constant flow rate. An overflow discharge pipe 36 is connected to the second electrolyte circulation tank 33, and the overflow is supplied to the catholyte circulation tank 17. The third electrolyte chamber 14 and the third electrolyte circulation tank 37 are connected by a pipe 38 and a pipe 39. The third electrolyte, which is an aqueous solution of sodium nitrate, is supplied to the third electrolyte circulation tank 3
7, circulate the pipe 38, the third electrolyte chamber 14, and the pipe 39 at a constant flow rate. A sodium nitrate aqueous solution supply pipe 40 and an overflow liquid extraction pipe 41 are connected to the third electrolyte circulation tank 37. The fourth electrolyte chamber 16 and the fourth electrolyte circulation tank 42 are connected by a pipe 43 and a pipe 44. The fourth electrolyte, which is an aqueous solution of sodium hydroxide, circulates through the fourth electrolyte circulation tank 42, the pipe 43, the fourth electrolyte chamber 16, and the pipe 44 at a constant flow rate. An overflow liquid extraction pipe 45 and a hydrogen discharge pipe 46 are connected to the fourth electrolyte circulation tank 42.

The uranyl nitrate having a concentration of 0.5M and 0.5%
A nitric acid aqueous solution containing 1 M silver nitrate is circulated between the anolyte circulation tank 26 of the electrolytic oxidizing means 1 and the anolyte chamber 4 to perform electrolysis.
Silver species in a divalent state (Ag
(II)) was produced, and waste containing 304 g of uranium dioxide was loaded into the anolyte circulation tank 26. Uranium dioxide is a metal oxide that dissolves in nitric acid to produce uranyl nitrate and is also an oxidizable substance, and electron exchange of 2 gram molecules per gram molecule participates in oxidation. Uranium dioxide was completely dissolved after electrolysis with an electric quantity of 2.7 Faraday. In this example, the catholyte contained no silver and the total metal concentration was 0.06M. A 4 M aqueous solution of sodium nitrate was supplied to the third electrolytic solution chamber 14 of the electrodialysis / concentration means to perform electrolysis so that the sodium nitrate concentration was maintained at 0.5 M. In the anolyte of electrolytic oxidizing means 1, 403 g of uranium dioxide produce 2.25 grams of molecular nitric acid (141.8 g) to produce uranyl nitrate.
g) was consumed, producing 20.3 g of water. In the anolyte compartment, 0.45 Faraday, which is an excess amount of the 2.7 Faraday consumed electricity other than the 2.25 Faraday consumed in the electron exchange reaction, is directly or Ag (I) on the anode.
Involved in the generation of oxygen indirectly via I), 4 g of water
Has been consumed. In addition, 135 g of water was moved to the catholyte along with hydrogen ions and metal ions moving to the catholyte in the course of electrolytic oxidation. Therefore, the amount of water reduced in the anolyte compartment 4 during electrolytic oxidation was 118.7 g.

In the catholyte, 1 gram molecule of nitric acid is reduced to 0.7 gram molecule of nitric oxide and 0.3 gram molecule of nitric oxide while the electrolysis is performed by 2.7 Faraday electricity by the electrolytic oxidation means. Gram molecules of nitrous acid and 1.7 grams of water
(30.6 g). Therefore, the amount of water increased in the catholyte compartment 5 during electrolytic oxidation was 165.6 g. The catholyte that has flowed out of the catholyte compartment 5 while the electrolysis is being carried out by the electrolytic oxidation means with the amount of 2.7 Faraday electricity passes through the first electrolytic solution circulating tank 20 of the electrodialysis / concentration means 2 to the first electrolyte solution. Electrolyte was supplied to the electrolyte solution chamber 10 and electrolysis was performed at an electric quantity of 5.4 Faraday. During the electrolysis, the circulating flow rate of the catholyte was kept constant at 0.36 liters per ampere of the electrolytic current of the electrolytic oxidizing means, and the integrated circulation amount was 1,563 liters. In the first electrolytic solution chamber 10 of the electrodialyzing / concentrating means 2, a silver species (Ag (II)) in a divalent valence state
Does not exist, and the nitrogen oxide discharge pipe 2 of the first electrolyte circulation tank 20
From 5 the nitric oxide (NO
x) was found. The catholyte is the first of the electrodialysis concentration means 2
While passing through the electrolyte chamber 10, 0.3 grams of nitrous acid, 0.5 grams of nitric oxide and 1.3 grams of water (23.4g) from 0.8 grams of nitric acid were added. As a result, 1.6 g of molecular oxygen was found from the oxygen discharge tube 24 of the catholyte circulation tank 17. While the catholyte of the electrolytic oxidation means is passing through the first electrolyte chamber of the electrodialysis concentrating means, 6.1 grams of molecular water (10
9.8 g) moved, and when returning to the catholyte circulation tank, the amount of water had increased by 32.4 g.

The second electrolytic solution chamber 12 of the electrodialysis / concentration means contains 2.43 g molecule of nitric acid (153.1 g) and 9.7 g molecule of water (175.4 g) and has a concentration of 46.6% (95.4 g). .5
M) nitric acid aqueous solution is generated and supplied to the catholyte circulation tank 17 as an overflow of the second electrolyte circulation tank 33, and the overflow of the catholyte circulation tank 17 is 697.6 g of nitric acid and 1677.3 g of nitric acid A concentration of 29.4% (5.5) containing water and 38.3 g of silver nitrate.
M) with a new nitric acid aqueous solution,
As a result, the overflow liquid in the anolyte circulation tank 28 is 38.
3 g silver nitrate, 443.6 g uranyl nitrate, 708.
2.25 liters of the effluent of the anode circulation tank 26 containing 8 g of nitric acid and 1734.0 g of water were filled in the effluent discharge pipe 32.
Was discharged from. The concentration of the dissolved substance was 0.1 M for silver nitrate,
Uranyl nitrate was 0.5M and nitric acid was 5.0M.

In the third electrolytic solution chamber 14 of the electrodialyzing / concentrating means 2, 219.8 g of sodium nitrate and 573.7 g of sodium nitrate were used.
Of water, containing 4.0 M of sodium nitrate, giving 5.4 Faraday of electricity and losing 2.43 g of molecules of sodium nitrate (206.6 g), at the same time 15.
8 grams of molecular water (284.3 g) is lost, 13.2 g
Sodium nitrate and 289.4 g of water, at a concentration of 0.3.
A 6 M aqueous solution of sodium nitrate was discharged from the overflow drain pipe 45. The utilization of sodium nitrate was 93.6%.

In the fourth electrolytic solution chamber 16 of the electrodialyzing / concentrating means 2, an electric quantity of 5.4 Faraday is given, and
43 grams of molecular sodium hydroxide (97.2 g) and 1
2.15 grams of molecular water (218.7 g), containing 30.8% (10.2 M) in concentration, yielding an overflow drain 45
And 2.7 grams of molecular hydrogen gas evolved from the hydrogen exhaust tube 46.

According to the present embodiment, the following effects can be obtained.

(1) Ag (I) is contained in the anolyte of the electrolytic oxidation means.
Since the waste containing the oxidizable metal oxide is loaded after the generation of I), no nitrogen oxide is generated from the anolyte, and there is no need to treat the exhaust gas.

(2) Nitric acid, nitric oxide and water, which are reduction products of nitric acid contained in the catholyte of the electrolytic oxidizing means, were regenerated to 80% nitric acid and could be used for oxidizing oxidizable substances.

(3) Nitrogen oxide released from the catholyte of the electrolytic oxidizing means was reduced to 20%, which facilitated off-gas cleaning.

(4) The water which has migrated from the anode chamber of the electrolytic oxidation means and increased in the cathode chamber due to electrolysis is removed in the first electrolytic solution chamber of the electrodialysis / concentration means so that the nitric acid concentration does not decrease. The generation of hydrogen and ammonia was prevented in the cathode compartment.

(5) Nitric acid was generated and recovered in the second electrolytic solution chamber with the water removed from the first electrolytic solution chamber of the electrodialysis concentrating means, and could be used for dissolving the metal oxide.

(6) By-product waste liquid contaminated with metal contained in waste is not generated, and waste treatment waste liquid is limited to one type.

(7) The sodium nitrate discharged from the electrodialysis concentrating means was discharged at a diluted concentration without being contaminated by the metal element contained in the waste, and the loss rate was 6%.

(Embodiment 2) An apparatus for treating waste containing a metal oxide and an oxidizable substance according to another embodiment of the present invention will be described below with reference to FIG.

The apparatus of this embodiment is provided with an electrodialysis desalting means 47 in addition to the electrolytic oxidation means 1 and the electrodialysis concentration means 2 of the first embodiment.

In the electrodialysis desalting means 47, a plurality of cation exchange membranes 50 and a plurality of anion exchange membranes 51 are alternately arranged between an anode 48 and a cathode 49. It has a diluent chamber 52 formed between the cathode side of the ion exchange membrane 51 and a concentrated chamber 53 formed between the cathode side of the cation exchange membrane 50 and the anode side of the anion exchange membrane 51. The ion exchange membrane is a strong acid cation exchange membrane and a strongly basic anion exchange membrane, both of which are standard membranes for electrodialysis. The diluent chamber 52 and the concentrate chamber 53 are arranged alternately. Each of the diluent chambers 52 is connected to a diluent circulation tank 56 via piping 54 and 55. The diluent circulates at a constant flow rate through the diluent circulation tank 56, the pipe 54, the diluent chamber 52, and the pipe 55. Each of the concentrate chambers 53 is provided with a pipe 57 and 5
At 8, it is connected to the concentrate circulation tank 59. The overflow discharge pipe 41 of the third electrolyte circulation tank 37 is connected to the diluent supply pipe 60. The concentrated overflow liquid discharge pipe 61 is connected to the concentrated liquid circulation tank 59. The concentrated overflow drain pipe 61 is connected to the third electrolyte supply pipe 40 of the electrodialysis / concentration means 2. Dilution overflow liquid discharge pipe 6
2 is connected to the diluent circulation tank 56 to discharge the diluent to the outside.

Uranyl nitrate having a concentration of 0.5M and 0.5%
A nitric acid aqueous solution containing 1 M silver nitrate is circulated between the anolyte circulation tank 17 of the electrolytic oxidizing means 1 and the anolyte chamber 4 to perform electrolysis.
Silver species in a divalent state (Ag
(II)) was produced, and waste containing 304 g of uranium dioxide was loaded into the anolyte circulation tank 28. Uranium dioxide is a metal oxide that dissolves in nitric acid to produce uranyl nitrate and is also an oxidizable substance, and electron exchange of 2 gram molecules per gram molecule participates in oxidation. Uranium dioxide was completely dissolved after electrolysis with an electric quantity of 2.7 Faraday. In this example, the silver concentration of the catholyte was 0.01M and the total metal concentration was 0.06M. A 4 M aqueous solution of sodium nitrate was supplied to the third electrolytic solution chamber 14 of the electrodialysis / concentration means 2 to perform electrolysis so that the sodium nitrate concentration was maintained at 1.0 M. In the anolyte of the electrolytic oxidation means 1, 403 g of uranium dioxide consumed 2.25 g molecule of nitric acid (141.8 g) to produce uranyl nitrate, and 20.3 g of water was produced. In the anolyte compartment, of the 2.7 Faraday consumed electricity, the excess electricity consumption of 0.45 Faraday other than 2.25 Faraday consumed in the electron exchange reaction was directly on the anode or via Ag (II). 4 g of water is consumed indirectly in connection with the generation of oxygen. In addition, 135 g of water was moved to the catholyte along with hydrogen ions and metal ions moving to the catholyte in the course of electrolytic oxidation. Therefore, the amount of water reduced in the anolyte compartment 4 during electrolytic oxidation was 118.7 g.

[0094] While electrolysis is being carried out with 2.7 Faraday's electricity by means of electrolytic oxidation, 1 gram molecule of nitric acid is reduced in the catholyte to 0.7 gram molecule of nitric oxide and 0.3 gram molecule of nitric oxide. Gram molecule of nitrous acid and 1.7 gram molecule of water (30.6 g). Therefore, the amount of water increased in the catholyte compartment 5 during electrolytic oxidation was 165.6 g.

While the electrolysis is being performed with 2.7 Faraday electricity by the electrolytic oxidizing means, the catholyte flowing out of the catholyte chamber 17 is supplied to the first electrolytic solution circulating tank 20 of the electrodialyzing / concentrating means 2.
, And supplied to the first electrolytic solution chamber 10 to perform electrolysis with an electric quantity of 5.0 Faraday. During the electrolysis, the circulating flow rate of the catholyte is kept constant at 0.36 liters per ampere of the electrolytic current of the electrolytic oxidizing means, and the integrated circulation amount is 156.
It was 3 liters. Ag (II) was slightly colored in the effluent of the catholyte compartment 17 of the electrolytic oxidation means 1, and high concentration of Ag (II) was present in the catholyte circulation tank 17. Nitrogen oxide (NOx) did not exist from the nitrogen oxide discharge pipe 25 of the first electrolytic solution circulation tank 20. While the catholyte passes through the first electrolyte compartment of the electrodialysis concentrating means, 0.3 grams of nitrous acid, 0.7 grams of nitric oxide and 1.7 grams of water (30.6 g) are added. Thus, 1.0 g molecule of nitric acid was regenerated, and 1.1 g molecule oxygen was found from the oxygen discharge tube 24 of the catholyte circulation tank 17. While the catholyte of the electrolytic oxidizing means is passing through the first electrolytic solution chamber of the electrolytic dialysis concentrating means, 5.7 gram molecules of water (101.7 g) move to the second electrolytic solution chamber. Upon returning to the tank, the amount of water had increased by 33.3 g.

In the second electrolytic solution chamber 33 of the electrodialyzing / concentrating means 2, the concentration containing 2.25 g molecule of nitric acid (141.8 g) and 9.1 g molecule of water (163.4 g) is 46.5% (9 .
6M) nitric acid aqueous solution is generated and supplied to the catholyte circulation tank 17 as an overflow of the second electrolyte circulation tank 33. The overflow of the catholyte circulation tank 17 contains 708.9 g of nitric acid and 1689.3 g of nitric acid. The concentration containing water and 38.3 g of silver nitrate is 29.6% (5.
4M) with an aqueous nitric acid solution
As a result, the overflow liquid in the anolyte circulation tank is 38.3.
g of silver nitrate, 443.6 g of uranyl nitrate, 708.8
g of nitric acid and 1734.0 g of water
2.25 liters of the effluent of No. 8 were discharged. The concentrations of the dissolved substances were 0.1M for silver nitrate, 0.5M for uranyl nitrate,
Nitric acid was 5.0M.

In the third electrolytic solution chamber 14 of the electrodialyzing / concentrating means 2, 217.4 g of sodium nitrate and 563.5 g of sodium nitrate were added.
A concentration of 4.0 M sodium nitrate, containing 5.0 Faraday of electricity, losing 2.25 grams of molecular nitrate (191.3 g);
At the same time, 14.6 g of molecular water (263.3 g) was lost, and a 1.0 M aqueous sodium nitrate solution containing 26.1 g of sodium nitrate and 300.2 g of water was discharged from the third electrolyte circulation tank 37. After being discharged through the overflow liquid discharge pipe 41, the sodium nitrate concentration of the electrodialysis desalting means 2 is set to 0.1.
It was supplied to a diluent circulation tank 56 maintained at 1M.

While the electrolytic oxidizing means is operating at 2.7 Faraday's electricity, it corresponds to 92% of 26.1 g of sodium nitrate supplied to the electrodialysis desalting means 2.
An aqueous solution of sodium nitrate having a concentration of 4.0 M containing 1 g of sodium nitrate and 62.9 g of water is generated in the concentrated solution chamber 53, and is discharged from the concentrated solution circulating tank 59 via the overflow solution discharge pipe 61 to the third electrolytic cell. The liquid was supplied to the liquid circulation tank 37. A 0.1 M aqueous sodium nitrate solution containing 2 g of sodium nitrate and 237.3 g of water was discharged from the dilute overflow discharge pipe 62. The utilization rate of sodium nitrate supplied to the third electrolytic solution chamber 37 was 99%.

In the fourth electrolytic solution chamber 16 of the electrodialyzing / concentrating means 2, an aqueous solution of sodium hydroxide having a concentration of 30.8% (10.2M) containing 90.0 g of sodium hydroxide and 202.5 g of water is provided. This produced 2.5 grams of molecular hydrogen gas from the hydrogen discharge tube 46. This aqueous sodium hydroxide solution was neutralized by mixing with a 33.9% (6.5 M) aqueous nitric acid solution containing 141.8 g of nitric acid and 276.3 g of water, and 191.3 g of sodium nitrate and 499 g of water. An aqueous sodium nitrate solution having a concentration of 27.7% (4.0 M) containing 0.1 g of water was prepared, and 2 g of sodium nitrate was added thereto.
The electrolyte was recovered. According to this embodiment, the effects (1) to (6) obtained in the first embodiment and the following effects are further obtained.

(1) Nitrite and nitrogen oxides generated by reduction of nitric acid in the catholyte of the electrolytic oxidation means can be mostly consumed to regenerate nitric acid.

(2) The current consumption associated with the regeneration of nitric acid is reduced in the electrodialysis concentration means.

(3) Nitrogen oxides are not generated from the first electrolytic solution circulation tank of the electrodialysis concentrating means, and there is no need for exhaust gas treatment.

(4) By combining the electrodialysis desalting means, the power consumption of the electrodialysis concentrating means could be reduced, and the loss of sodium nitrate supplied to the third electrolyte chamber could be reduced to 1% or less. .

(5) A concentrated aqueous sodium hydroxide solution is recovered from the fourth electrolytic solution chamber of the electrodialyzing / concentrating means, and mixed with nitric acid to neutralize the aqueous solution to be supplied to the third electrolytic solution chamber. Could be prepared.

(Embodiment 3) An apparatus for treating waste containing a metal oxide and an oxidizable substance according to another embodiment of the present invention will be described below with reference to FIG.

In the processing apparatus shown in FIG. 3 of the present embodiment, the cathode 63 of the electrolytic dialysis concentrator 2 in the processing apparatus shown in FIG. 2 uses an electrode material obtained by attaching platinum to a porous carbon fiber material from a metal mesh such as silver or nickel. By contacting one surface of the electrode, which is negatively charged, with the electrolyte, and contacting the other surface with air or oxygen, oxygen diffuses inside the electrode to form a contact with the electrolyte. An air diffusion cathode 63 which has an action of generating water by combining with hydrogen at the contact surface, to which an air supply pipe 64 and an air discharge pipe 65 are connected.

In the processing apparatus shown in FIG. 3 of this embodiment, the first electrolytic solution circulating tank 20 of the processing apparatus shown in FIG. 2 is omitted, and the pipe 21 connects the catholyte circulating tank 17 and the first electrolytic solution chamber 10. I have. Further, the concentrate circulation tank 59 of the electrodialysis desalting means 47 of the processing apparatus of FIG. 2 is deleted, the pipe 57 is replaced with a pipe 67, connected to the third electrolyte circulation tank 37, and the pipe 58 is connected to the pipe 66. It is replaced and connected to the third electrolyte circulation tank 37.

In this embodiment, an aqueous nitric acid solution containing uranyl nitrate having a concentration of 0.5 M and silver nitrate having a concentration of 0.1 M is applied between the anolyte circulation tank 28 and the anolyte chamber 4 of the electrolytic oxidizing means 1 as in the second embodiment. And electrolysis is performed to generate silver species (Ag (II)) in a divalent valence state in the anolyte, and the anolyte circulation tank 28 is loaded with 304 g of waste containing uranium dioxide. did. Uranium dioxide is a metal oxide that dissolves in nitric acid to produce uranyl nitrate and is also an oxidizable substance, and electron exchange of 2 gram molecules per gram molecule participates in oxidation. Uranium dioxide was completely dissolved after electrolysis with an electric quantity of 2.7 Faraday. In this example, the silver concentration of the catholyte was 0.03M and the total metal concentration was 0.18M. A 4 M aqueous sodium nitrate solution is supplied to the third electrolytic solution chamber 14 of the electrodialysis / concentration means 2 to perform electrolysis, and the sodium nitrate concentration becomes 1.0 M.
To be kept. In the anolyte of electrolytic oxidation means 1
403 g of uranium dioxide consumes 2.25 g molecule of nitric acid (141.8 g) to produce uranyl nitrate, and 20.3 g
Of water formed. In the anolyte compartment, of the 2.7 Faraday electricity consumed, 0.45 Faraday, which is the excess electricity consumed in addition to the 2.25 Faraday consumed in the electron exchange reaction, either directly on the anode or via Ag (II). 4 g of water is consumed indirectly in connection with the generation of oxygen. In addition, 135 g of water was moved to the catholyte along with hydrogen ions and metal ions moving to the catholyte in the course of electrolytic oxidation.
Therefore, the amount of water reduced in the anolyte compartment 4 during electrolytic oxidation is 1
The weight was 18.7 g.

During electrolysis with 2.7 Faraday's electricity by the electrolytic oxidation means, 1 gram molecule of nitric acid is reduced in the catholyte to 0.7 gram molecule of nitric oxide and 0.3 gram molecule of nitric oxide. Gram molecules of nitrous acid and 1.7 grams of water
(30.6 g). Therefore, the amount of water increased in the catholyte compartment 5 during electrolytic oxidation was 165.6 g. The catholyte which flowed out of the catholyte compartment 17 while the electrolysis was being carried out by 2.7 Faraday electricity by the electrolytic oxidizing means was passed through the first electrolytic solution circulating tank 10 of the electrolytic dialysis concentrating means 2 and the catholyte was discharged. The mixture was returned to the circulation tank 17 and electrolysis was performed with an amount of 4.6 Faraday electricity. During the electrolysis, the circulating flow rate of the catholyte was kept constant at 0.2 liters per ampere of the electrolytic current of the electrolytic oxidizing means, and the integrated circulation amount was 868 liters.
Ag in the effluent of the catholyte compartment 5 of the electrolytic oxidation means 1 is slightly
Coloring of (II) was observed, and high concentration of Ag (II) was present in the catholyte circulation tank 17. While the catholyte passes through the first electrolyte compartment of the electrodialysis concentrating means, 0.3 grams of nitrous acid, 0.7 grams of nitric oxide and 1.7 grams of water (30.6 g) are added. From the nitric acid of the catholyte circulation tank 17 was regenerated to 1.0 g molecule of nitric acid.
From No. 4, 0.95 gram molecules of oxygen were found. While the catholyte of the electrolytic oxidizing means 1 passes through the first electrolytic solution chamber 10 of the electrolytic dialysis concentrating means 2, 6.4 gram molecules of water (115.1 g) move to the second electrolytic solution chamber. When returning to the catholyte circulation tank 17, the amount of water had increased by 19.9 g.

In the second electrolytic solution chamber 12 of the electrodialyzing / concentrating means 2, the concentration containing 2.07 g molecule of nitric acid (130.4 g) and 9.5 g molecule of water (171.1 g) is 43.3% (83.3%). .
7M), is supplied to the catholyte circulation tank 17 as an overflow of the second electrolyte circulation tank 33, and the overflow of the catholyte circulation tank 17 is supplied from the nitric acid aqueous supply pipe 27. As a result of mixing with a fresh nitric acid aqueous solution having a concentration of 30.0% (5.6 M) containing 720.2 g of nitric acid and 1681.6 g of water and supplying the mixed solution to the anolyte circulation tank 28, the anolyte circulation tank 28 was produced.
2.25 liters containing 38.3 g of silver nitrate, 443.6 g of uranyl nitrate, 708.8 g of nitric acid and 1734.0 g of water were discharged. The concentrations of the dissolved substances were 0.1 M for silver nitrate, 0.5 M for uranyl nitrate, and 5.5 M for nitric acid.
OM. Third electrolyte chamber 1 of electrodialysis concentration means 2
In step 4, 200.0 g of sodium nitrate and 522.
A supply of 4.0 M sodium nitrate containing 1 g of water was provided, giving a charge of 4.6 Faraday and 2.0
Seven grams of molecules of sodium nitrate (176.0 g) are lost, while at the same time 13.5 grams of water (242.2 g) are lost, containing 24.0 g of sodium nitrate and 279.9 g of water. A 0.0M aqueous solution of sodium nitrate is discharged from the third electrolyte circulation tank 37 through the overflow discharge pipe 41, and the sodium nitrate concentration of the electrodialysis and desalting means 47 is reduced to 0.0.
It was supplied to a diluent circulation tank 56 maintained at 1M.

While the electrolytic oxidizing means 1 is operated at an electric quantity of 2.7 Faraday, it corresponds to 92% of 24.0 g of sodium nitrate supplied to the electrodialysis desalting means 47.
2.1 g of sodium nitrate and 57.9 g of water were transferred from the third electrolytic solution circulating tank 37 to an aqueous solution of sodium nitrate circulating at a constant flow rate through the pipe 67, the concentrate chamber 53, and the pipe 66. The diluent was a 0.1 M aqueous sodium nitrate solution containing 2 g of sodium nitrate and 222.0 g of water. The utilization rate of sodium nitrate supplied to the third electrolytic solution chamber was 99%.

In the fourth electrolytic solution chamber 16 of the electrodialyzing / concentrating means 2, an aqueous solution of sodium hydroxide having a concentration of 26.7% (8.6M) containing 82.8 g of sodium hydroxide and 227.7 g of water is contained. As a result, no hydrogen gas was generated in the fourth electrolytic solution chamber 42. This aqueous sodium hydroxide solution was added to 13
Contains 0.4 g nitric acid and 194.3 g water, at a concentration of 40.2
% (8.0 M) aqueous nitric acid and neutralized.
An aqueous solution of sodium nitrate having a concentration of 27.7% (4.0 M) containing 0 g of sodium nitrate and 459.3 g of water was prepared, and 2 g of sodium nitrate was added to collect a third electrolytic solution.

In this embodiment, the effects obtained in the first embodiment (1) to (6) and the second embodiment (1) to (5) can be obtained, and further, the following effects can be obtained.

(1) The concentration of silver contained in the catholyte of the electrolytic oxidizing means is increased, the amount of Ag (II) generated in the first electrolytic solution chamber of the electrolytic dialysis / concentration means is increased, and Ag (II) is introduced into the catholyte chamber. Due to the presence, even if the flow rate of the catholyte is reduced in the catholyte compartment, nitric oxide is not generated as a gas, and the current efficiency related to the oxidation of the reduction product of nitric acid is increased.

(2) No hydrogen is generated in the fourth electrolytic solution chamber of the electrodialyzing / concentrating means, and there is no need to treat exhaust gas.

(3) Since the cathode is polarized by oxygen in the fourth electrolytic solution chamber of the electrodialyzing / concentrating means and the potential becomes higher than that of the hydrogen generating electrode, the electrode voltage of the electrodialyzing / concentrating means can be low, and the consumption is reduced. Power is reduced.

(4) Since oxygen gas generated from the catholyte circulation tank of the electrolytic oxidizing means can be introduced and used, there is no need for exhaust gas treatment.

(5) The piping related to the first electrolytic solution circulating tank and the concentrated solution circulating tank can be eliminated, and the apparatus can be simplified.

[0119]

According to the first aspect of the present invention, nitric acid, nitric oxide, and water, which are reduction products of nitric acid, contained in the catholyte of the electrolytic oxidizing means are regenerated into nitric acid at a high yield to obtain oxidizable substances. At the same time that it can be used to oxidize substances, water that moves from the anolyte to the catholyte is removed from the catholyte by electrolytic oxidation means to keep the nitric acid concentration high, and undesired side reactions such as the generation of hydrogen and ammonia in the catholyte Was effectively prevented.

According to the second aspect of the present invention, the effects of the first aspect of the present invention are obtained, and nitrogen oxides are produced when the oxidizable metal oxide is dissolved in the anolyte of the electrolytic oxidizing means. No need to treat exhaust gas.

According to the third aspect of the present invention, the effect of the first aspect of the present invention is produced, and the reduction product of nitric acid does not accumulate in the catholyte of the electrolytic oxidizing means. Can be regenerated to nitric acid.

According to the fourth aspect of the present invention, the effect of the first aspect of the present invention is produced, and the amount of nitric oxide which is transferred to the gas phase among the reduction products of nitric acid contained in the catholyte of the electrolytic oxidation means is reduced. be able to.

According to the fifth aspect of the present invention, the effect of the first aspect of the present invention is produced, and the amount of nitric oxide which is transferred to the gas phase among the reduction products of nitric acid contained in the catholyte of the electrolytic oxidation means is further reduced. And the current consumption required for nitric acid regeneration is reduced.

According to the invention of claim 6, it is possible to suppress the generation of the amount of nitric oxide among the reduction products of nitric acid contained in the catholyte of the electrolytic oxidation means, and it is possible to reduce the flow rate of the catholyte. Thus, the current consumption required for the regeneration of nitric acid is further reduced.

According to the seventh aspect of the present invention, the effects of the first aspect of the present invention are obtained, and an aqueous nitric acid solution containing metal ions contained in the waste is supplied to the catholyte chamber and the anolyte chamber of the electrolytic oxidation means. By supplying, it is possible to replenish nitric acid which needs to be added to convert the metal oxide into nitrate.

According to the invention of claim 8, the effect of the invention of claim 1 is produced, and the concentrated aqueous solution of sodium hydroxide is recovered from the fourth electrolytic solution chamber of the electrodialyzing / concentrating means.
By mixing and neutralizing with nitric acid, an aqueous solution of sodium nitrate to be supplied to the third electrolytic solution chamber could be prepared.

According to the ninth aspect of the present invention, the effect of the first aspect of the present invention is obtained, and the power consumption of the electrodialysis concentrating means can be reduced by combining the electrodialysis desalting means. The loss of the supplied sodium nitrate could be reduced.

According to the tenth aspect, the effects of the first, second, third, fourth, seventh, eighth, and ninth aspects of the invention are produced, and particularly, the effects of the tenth aspect are achieved. 5
The effect of the invention of the present invention can be embodied.

According to the eleventh aspect, the effects of the first, second, seventh, eighth, or ninth aspects are produced, and in particular, the effect of the sixth aspect is realized. And the configuration of the apparatus can be simplified.

According to the twelfth aspect of the present invention, the effect of the first aspect of the present invention is obtained, and no hydrogen is generated in the fourth electrolytic solution chamber of the electrolytic dialysis concentrating means, so that it is not necessary to treat the exhaust gas. Since the cathode is polarized with oxygen in the fourth electrolytic solution chamber of the electrodialyzing / concentrating means and has a higher potential than that of the hydrogen generating electrode, the electrode voltage of the electrodialyzing / concentrating means can be low, and the power consumption is reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an apparatus for treating waste containing a metal oxide and an oxidizable substance according to a preferred embodiment of the present invention.

FIG. 2 is a configuration diagram of a waste treatment apparatus including a metal oxide and an oxidizable substance according to another embodiment of the present invention.

FIG. 3 is a configuration diagram of an apparatus for treating waste containing a metal oxide and an oxidizable substance according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... electrolytic oxidation means, 2 ... electrolytic dialysis concentrating means, 4 ... anolyte chamber, 5 ... catholyte chamber, 6 ... anode, 9 ... 1st cation exchange membrane, 10 ... 1st electrolyte chamber, 11 ... anion Exchange membrane, 12
... second electrolyte chamber, 13 ... second cation exchange membrane, 14 ... third electrolyte chamber, 15 ... cathode, 16 ... fourth electrolyte chamber, 47 ...
Electrodialysis desalting means, 52: diluent chamber, 53: concentrate chamber.

Claims (12)

[Claims] An anolyte containing nitric acid and a waste containing an oxidizable substance are brought into contact with each other, oxidized and treated using silver species in a divalent valence state as a medium, and reduced in an electrolyte. The silver ions in the monovalent valence state generated by the method are one of the waste treatment methods for regenerating silver species in the divalent valence state in the anolyte of the electrolytic oxidation means. Cathode compartment liquid of the electrolytic oxidation means, which is a nitric acid aqueous solution containing nitrogen oxides and a part of silver and other metal ions present in the anolyte, and having an increased water content,
A first electrolyte compartment partitioned by an anode and a first cation exchange membrane,
A second electrolyte compartment partitioned by the first cation exchange membrane and the anion exchange membrane, a third electrolyte compartment partitioned by the anion exchange membrane and the second cation exchange membrane, and the second cation exchange The first electrolytic solution is supplied to the first electrolytic solution chamber of the electrolytic dialysis / concentration means, which is composed of a fourth electrolytic solution chamber defined by a membrane and a cathode, and an aqueous sodium nitrate solution is supplied to the third electrolytic solution chamber.
An aqueous nitric acid solution is circulated in the electrolytic solution chamber, an aqueous sodium hydroxide solution is circulated in the fourth electrolytic solution chamber to perform electrodialysis, and nitrous acid dissolved in the aqueous nitric acid solution supplied to the first electrolytic solution chamber is used. Nitrogen oxide is oxidized by a potential difference on the anode to regenerate nitric acid, and water is removed from the first electrolytic solution chamber along with hydrogen ions and metal ions that carry charges from the first electrolytic solution chamber to the second electrolytic solution chamber.
A method for treating waste containing a metal oxide and an oxidizable substance, wherein the nitric acid concentration in an aqueous nitric acid solution is increased by removing through a cation exchange membrane and refluxed to the cathode chamber of the electrolytic oxidizing means. . 2. A waste material containing a metal oxide and an oxidizable substance is supplied to an anolyte circulating tank of the electrolytic oxidizing means to which a nitric acid aqueous solution containing a silver species in a divalent valence state is supplied. 2. The metal according to claim 1, wherein the oxidizable substance is oxidized by the action of silver species in a divalent state regenerated by electrolysis and the soluble metal oxide is treated as a nitrate. A method for treating waste containing oxides and oxidizable substances. 3. The electrolytic oxidizing means is supplied with a liquid from the cathode chamber through a circulating tank into which an effluent from the first electrolytic solution chamber of the electrolytic dialysis / concentrating means flows. The supply of the solution is made from a circulating tank into which the catholyte solution of the electrolytic oxidizing means flows, and the amount of electricity added to the first electrolytic solution of the electrolytic dialysis concentrating means is added to the catholyte solution of the electrolytic oxidizing means. The method for treating waste containing a metal oxide and an oxidizable substance according to claim 1, wherein the amount is larger than an amount of electricity. 4. A flow rate of an electrolytic solution supplied to or circulated to the cathode chamber liquid chamber of the electrolytic oxidizing means is at least per one ampere of a current flowing through the electrolytic oxidizing means.
4. The method for treating waste containing a metal oxide and an oxidizable substance according to claim 3, wherein the rate is 0.36 l / min. 5. The electrolytic solution supplied from the catholyte chamber of the electrolytic oxidizing means to the first electrolytic chamber of the electrolytic dialysis concentrating means contains silver ions at a concentration of at least 0.01 M or more. A potential of at least 2.0 V is applied to the anode of the electrodialysis desalting means as compared with the hydrogen standard electrode,
5. The metal oxide according to claim 4, wherein the dialysate is electrodialyzed by applying an excessive amount of electricity so as to generate a silver species in a divalent state in the first electrolytic solution. A method for treating waste containing oxidizing substances. 6. An electrolytic solution supplied from the catholyte chamber of the electrolytic oxidizing means to the first electrolytic chamber of the electrolytic dialysis concentrating means contains silver ions at a concentration of at least 0.02 M or more. A potential of at least 2.0 V is applied to the anode of the electrodialysis desalting means as compared with the hydrogen standard electrode,
Until the first electrolytic solution is supplied to the catholyte compartment of the electrolytic oxidizing means and flows out of the catholyte compartment, an excess amount of electricity is added so that silver species in a divalent state remain. 4. The method for treating waste containing a metal oxide and an oxidizable substance according to claim 3, wherein the waste is electrodialyzed. 7. An electrolysis while supplying water to said second electrolytic solution chamber of said electrolytic dialysis concentrating means, and said second electrolytic solution chamber passes through said first cation exchange membrane from said first electrolytic solution chamber. Supplying a second electrolytic solution having a concentration adjusted to 10 M or less to a circulating liquid tank for supplying an electrolytic solution to the catholyte chamber of the electrolytic oxidizing means, wherein The effluent of the tank is mixed with an aqueous nitric acid solution containing silver nitrate to supply metal oxide to nitrate and supplied to a circulating liquid tank for supplying an electrolytic solution to the anolyte chamber. Item 6. A method for treating waste containing the metal oxide and the oxidizable substance according to Item 1. 8. An aqueous solution of nitric acid is added to an aqueous solution of sodium hydroxide produced in the fourth electrolytic solution chamber of the electrolytic dialysis / concentrating means to neutralize the aqueous solution to form an aqueous sodium nitrate solution. 0.5M to 1.
The method for treating waste containing a metal oxide and an oxidizable substance according to claim 1, wherein the concentration is maintained at a constant concentration of 0M. 9. The electrodialysis desalination means in which a plurality of cation exchange membranes and a plurality of anion exchange membranes are alternately arranged, whereby a diluent chamber and a concentrate chamber are alternately arranged therebetween. An aqueous solution of sodium nitrate of the third electrolytic solution of the electrolytic dialysis / concentration means having a reduced concentration of sodium nitrate is supplied to the diluent solution chamber, and the salt concentration of the diluent is adjusted to 0.1 M.
The concentration is reduced to below and discharged to the outside. On the other hand, the salt concentration of the concentrated solution generated from the concentrated solution chamber is set to 3.5M or more, and the dialysis is performed in addition to the third electrolytic solution guided to the third electrolytic solution chamber. The method for treating waste containing a metal oxide and an oxidizable substance according to claim 1, wherein the waste is provided. 10. An electrolytic oxidizing means comprising an anolyte compartment, a catholyte compartment and a diaphragm separating them, a first electrolyte compartment and a second electrolyte compartment.
An electrolytic dialysis salt decomposition means comprising an electrolytic solution chamber, a third electrolytic solution chamber, a fourth electrolytic solution chamber and an ion exchange membrane for isolating them, and a diluent chamber and a concentrate chamber comprising a number of ion exchange membranes. A circulating fluid tank for receiving an aqueous nitric acid solution containing nitrous acid and nitric oxide from the catholyte compartment and supplying the nitric acid aqueous solution to the first electrolytic compartment; a pipe; Nitric acid is regenerated from the liquid chamber,
A circulating liquid tank for receiving the aqueous nitric acid solution from which water has been removed and supplying the liquid to the cathode chamber liquid chamber; and a pipe. A path for supplying the circulating tank; and a path for mixing the overflow of the catholyte circulating tank with an aqueous nitric acid solution containing silver nitrate and supplying the mixture to the anolyte circulating tank. A path for discharging the flowing liquid to a specific treatment step; and a path for supplying an overflow of the circulating tank for the third electrolytic solution to the circulating liquid tank for the diluting liquid of the electrodialysis desalting means. A path for supplying the overflow of the concentrated liquid circulation tank to the third electrolyte circulation tank of the electrolytic dialysis concentrating means; and a path for discharging the overflow of the diluted liquid circulation tank. An apparatus for treating waste containing a metal oxide and an oxidizable substance. 11. An electrolytic oxidizing means comprising an anolyte compartment, a catholyte compartment and a diaphragm separating them, a first electrolyte compartment and a second electrolyte compartment.
An electrolytic dialysis salt decomposition means comprising an electrolytic solution chamber, a third electrolytic solution chamber, a fourth electrolytic solution chamber and an ion exchange membrane for isolating them, and a diluent chamber and a concentrate chamber comprising a number of ion exchange membranes. It receives an aqueous nitric acid solution containing a high concentration of silver species in a divalent valence state, which is electrolytically generated in the first electrolytic solution chamber, and is supplied to the catholyte chamber. And a common catholyte circulation tank and respective pipes for receiving a nitric acid aqueous solution in which the silver species in a divalent valence state is reduced in the catholyte compartment and supplying the same to the first electrolyte compartment, A channel for supplying the overflow of the second electrolyte circulation tank to the catholyte circulation tank of the electrolytic oxidizing means; mixing the overflow of the catholyte circulation tank with a nitric acid aqueous solution containing silver nitrate; A path for supplying the anolyte circulation tank is provided; A path for discharging the overflow of the third electrolytic solution circulating tank to the circulating liquid tank of the diluting solution of the electrodialysis desalting means. (3) An aqueous solution of sodium nitrate whose concentration has been reduced by electrodialysis is received in the electrolytic solution chamber, and supplied to the concentrated solution chamber of the electrodialysis desalting means. A metal oxide, comprising: a common third electrolytic solution circulation tank for receiving and supplying the third electrolytic solution chamber and respective pipes; and a path for discharging an overflow from the diluent circulation tank. And waste treatment equipment containing oxidizable substances. 12. The method according to claim 1, wherein said cathode of said electrolytic dialysis concentrating means is a gas diffusive electrode, and supplies air to the back side of the electrode surface in contact with said fourth electrolytic solution which is an aqueous solution of sodium hydroxide. 1. A method for treating waste containing the metal oxide and the oxidizable substance.