JPH03238754A - Manufacture of plate for alkaline storage battery - Google Patents

Abstract

PURPOSE:To reduce the concentration of lead nitrate in waste liquid discharged outside a plant by reducing the aforesaid concentration in a neutralization chamber and at least one of two water washing chambers used at least first for a water washing process via a crystallization method or an electrolytic method. CONSTITUTION:The concentration of lead nitrate in a neutralization chamber A and at least one of two water washing chambers used at least first for a water washing process is lowered via a crystallization method or an electrolytic method. As a result, an amount of lead nitrate deposited on a substrate pulled up from the first water washing chamber can be reduced, and an amount of lead nitrate washed away from the substrate when immersed in the water washing chamber for the next water washing process is reduced. According to the aforesaid process, it is possible to reduce the concentration of lead nitrate such as natrium or potassium in waste liquid discharged outside a plant.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a method for manufacturing electrode plates for alkaline storage batteries, and in particular to a method for reducing the concentration of nitrates such as sodium or potassium in waste liquid discharged outside a factory. This relates to a manufacturing method that can be used.

[Prior Art] In a conventional method for manufacturing electrode plates for alkaline storage batteries, manufacturing is carried out according to the manufacturing process diagram shown in FIG. 4. In the sintering process, a porous nickel sintered substrate is created which is used as an active material holder. Next, in the impregnation step, the sintered substrate is impregnated with nitrate such as nickel or cadmium, and in the neutralization step, this substrate is immersed in a neutralization tank containing an alkaline aqueous solution containing an alkali hydroxide such as sodium hydroxide or potassium hydroxide. The nitrate impregnated into the substrate is changed into an active material such as nickel hydroxide or cadmium hydroxide. In the next water washing step, this substrate is immersed in a water washing tank to wash away substances such as nitrates and alkali hydroxides adhering to the substrate. After that, the substrate is dried by a drying process. A predetermined amount of active material is filled into the sintered substrate by repeating the series of active material filling operations from the impregnation step to the drying step several times. After that, the electrode plate is completed through a chemical conversion process, a water washing process, and a drying process.

In the above-mentioned neutralization step, the nitrate impregnated into the sintered substrate reacts with the alkali hydroxide to become an active material such as nickel hydroxide or cadmium hydroxide. However, when such a reaction occurs, new nitrate as a by-product is also produced at the same time as the active material is produced. For example, when the nitrate to be impregnated in the impregnation step is nickel nitrate and the alkaline aqueous solution in the neutralization tank is a sodium hydroxide aqueous solution, the reaction formula for producing the active material and by-products is as follows.

N1(NO3) 2 +2NaO)1-+N1(OH
) 2 +2NaN03 As shown in the above formula, nickel nitrate [
N1(NO3) 2 ] is sodium hydroxide [NaO
When reacting with nickel hydroxide [Ni H], nickel hydroxide [Ni
(OH) 2 ] is produced, and sodium nitrate [NaN03], which is a nitrate, is produced as a by-product.

The by-product nitrate thus generated in the neutralization step is dissolved and accumulated in the alkaline aqueous solution in the neutralization tank. As the number of times the sintered substrate impregnated with nitrate is immersed in the neutralization tank increases, the concentration of nitrate in the neutralization tank increases, and conversely, the concentration of alkali hydroxide decreases. Normally, when the concentration of the alkaline hydroxide solution in the neutralization tank becomes 10vt% or less, it is disposed of as waste liquid, but even if the alkaline hydroxide waste liquid containing nitrates is neutralized or diluted and discharged into rivers, etc. Nitrate, a nitrogen-containing compound, causes eutrophication of rivers. Therefore, in the past, the nitrate component dissolved in the alkaline aqueous solution in the neutralization tank was removed using a crystallization method or a method that combined a crystallization method and an electrolytic method to reduce the nitrate concentration in the neutralization tank. The nitrate concentration in waste liquid discharged outside the electrode plate manufacturing process was reduced.

[Problems to be Solved by the Invention] However, even if the nitrate concentration in the neutralization tank is reduced, when the substrate pulled up from the neutralization tank is immersed in the washing tank, nitrate as a reaction product adhering to the substrate will flow into the washing tank. washed away. Drainage from washing tanks is often discharged directly into rivers, etc. Therefore, there is a limit to reducing the nitrate concentration in wastewater by simply reducing the nitrate concentration in the neutralization tank as in the conventional method.

An object of the present invention is to provide a manufacturing method that can lower the concentration of nitrates such as sodium or potassium in waste liquid discharged outside the factory in the manufacturing process of electrode plates for alkaline storage batteries.

[Means for Solving the Problems] The method of manufacturing an electrode plate for an alkaline storage battery of the present invention includes immersing a substrate impregnated with nitrate in a neutralization tank containing an aqueous alkali hydroxide solution to turn the nitrate into an active material. The invention of claim 1 is characterized in that the substrate is immersed in at least two washing tanks and then washed with water to produce an electrode plate for an alkaline storage battery. In the invention of claim 2, the electrode plate for an alkaline storage battery is characterized by reducing the nitrate concentration in the washing tank in which water washing is performed at least first by a crystallization method or an electrolytic method. In the invention of claim 3, wherein the alkaline storage battery electrode plate is characterized in that the washing tank is a washing tank that does not substantially drain water, the nitrate concentration of the alkaline aqueous solution in the neutralization tank is reduced by a crystallization method. First, the nitrate concentration in the washing tank where water washing is performed is reduced by diaphragm electrolysis.

In the invention according to claim 4, the diaphragm electrolysis method is carried out using a diaphragm electrolysis device that includes an anode chamber, a stock solution chamber, and a cathode chamber, and each chamber is separated only by an anion exchange membrane.

Furthermore, the invention of claim 5 includes a diaphragm electrolyzer comprising an anode chamber, a stock solution chamber, and a cathode chamber, each of which is separated only by an anion exchange membrane, and an anode chamber, a stock solution chamber, and a cathode chamber. Then, the diaphragm electrolysis method is performed using a composite device in which the above-mentioned diaphragm electrolysis devices are combined in series, each chamber being separated only by a cation exchange membrane.

[Function] As in the invention of claim 1, when the nitrate concentration in the neutralization tank and at least the first washing tank of the at least two washing tanks is reduced, the nitrate concentration in the neutralization tank and at least the first washing tank of the at least two washing tanks is reduced. The amount of nitrate solution that adheres to the substrate being pulled up can be reduced.

Therefore, when the substrate pulled up from the neutralization tank is first immersed in the washing tank where water washing is performed, the amount of nitrate washed off from the substrate into the washing tank is reduced. Furthermore, since the nitrate concentration of the washing liquid in this washing tank is reduced by crystallization or electrolysis, it is possible to reduce the amount of nitrate that adheres to the substrate pulled out of the washing tank. The amount of nitrate that is washed off the substrate into the wash tank when the substrate is immersed in the wash tank where the next water wash is performed is significantly reduced. Therefore, even if the waste liquid discharged from these washing tanks is discharged outside the factory, the concentration of nitrates such as sodium or potassium in the waste liquid is reduced.

As in the invention of claim 2, if the washing tank for reducing the nitrate concentration is a washing tank that does not substantially drain water (hereinafter referred to as washing tank A), the waste liquid discharged outside the factory is washed in the washing tank A. The only waste water is from another washing tank (hereinafter referred to as washing tank B) in which the substrates that have completed the process are immersed. Since the nitrate is recovered in the washing tank A, the amount of nitrate adhering to the substrate immersed in the washing tank B is reduced.

Therefore, water can be drained from the washing tank B.

Furthermore, since the crystallization method makes use of differences in solubility, it has a limited ability to reduce nitrate concentration compared to the diaphragm electrolysis method, but it can crystallize large amounts of nitrate using small equipment and with low power consumption. On the other hand, although the diaphragm electrolysis method can separate and remove nitrate into ions even from dilute concentrations compared to the crystallization method, it requires Power consumption is high, and the area of the dialysis membrane must be increased, resulting in an increase in the size of the device. The nitrate concentration in the neutralization tank is higher than the nitrate concentration in the washing tank where water washing is performed first.

Therefore, as in the invention of claim 3, if the nitrate concentration of the alkaline aqueous solution in the neutralization tank is reduced by the crystallization method, and at least the nitrate concentration in the washing tank where water washing is performed first is reduced by the diaphragm electrolysis method. , low power consumption and simple equipment make it possible to reduce operating costs and significantly reduce the nitrate concentration of the waste liquid discharged outside the factory.

When the nitrate concentration in the washing tank is reduced by using a diaphragm electrolyzer in which the anode chamber, stock solution chamber, and cathode chamber are separated only by an anion exchange membrane as in the invention of claim 4, the water containing nitrate ions is reduced. The liquid flows only in the stock solution chamber, and the electrode plate placed in the cathode chamber does not come into direct contact with the washing liquid. Therefore, nitrate ions are not reduced on the cathode plate and reaction intermediates are not produced, and corrosion of the cathode plate can be prevented. Furthermore, even if a reaction intermediate were to be produced in the cathode chamber, the presence of the ion exchange membrane prevents the reaction intermediate from being mixed into the washing liquid in the stock solution chamber.

According to the invention of claim 5, a diaphragm electrolyzer is provided with an anode chamber, an undiluted solution chamber, and a cathode chamber, and each of the chambers is separated only by an anion exchange membrane, and an anode chamber, an undiluted solution chamber, and a cathode chamber. Therefore, if a composite device is used in which a diaphragm electrolyzer in which each chamber is separated only by a cation exchange membrane is combined in series, nitrate ions are recovered in the diaphragm electrolyzer equipped with an anion exchange membrane, and nitrate ions are collected in the diaphragm electrolyzer equipped with an anion exchange membrane. There is an advantage that the nitrate concentration in the washing liquid can be reliably reduced by recovering alkali ions using a diaphragm electrolyzer equipped with an ion exchange membrane, and the pH of the washing liquid can be appropriately controlled.

[Example] An example of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a manufacturing process diagram of an electrode plate for an alkaline storage battery in one embodiment of the present invention. In this example, the water washing process is performed twice. Hereinafter, the order in which the electrode plate substrate is immersed will be referred to as a primary rinsing process and a secondary rinsing process, and the rinsing tank in which the substrate is immersed in each rinsing process will be described as a primary rinsing tank and a secondary rinsing tank. The steps in this example are the same as the conventional example shown in Figure 4, except that the number of washing steps is increased by one and the nitrate concentration is reduced in the first washing step, so the common steps are as follows. The explanation will be omitted. A method for reducing the nitrate concentration in the neutralization step and the primary water washing step will be outlined below, and then its details will be explained in detail.

First, as in the prior art, in this embodiment, the nitrate concentration in the alkaline hydroxide solution in the neutralization tank is lowered by crystallization. After completing the neutralization process in the neutralization tank, the substrate is immersed in a primary washing tank to thoroughly wash away nitrates adhering to the substrate. 1
The secondary rinsing tank is a rinsing tank in which water is not substantially drained, and in this embodiment, the nitrate concentration in the rinsing liquid in the primary rinsing tank is reduced by diaphragm electrolysis.

Next, the substrate that has undergone the primary water washing step is immersed in a secondary water washing tank to which fresh water is supplied at a flow rate of 10β/min. According to this embodiment, it is possible to suppress the nitrate concentration in the waste water discharged from the secondary washing tank to a considerably low level.

Next, a method for reducing the nitrate concentration in the neutralization tank and the primary washing tank will be explained in more detail. First, in the neutralization tank, a crystallizer is attached to the neutralization tank, which cools the solution drawn from the neutralization tank using a cooling means, crystallizes the nitrate, and recovers the nitrate. Circulate through the device to reduce nitrate concentrations. Upon cooling, the nitrates contained in the alkaline hydroxide solution precipitate due to the difference in solubility with respect to temperature. When the solution in the neutralization tank is a sodium hydroxide solution, the setting conditions of the crystallizer are set to cooling temperature 1.
The temperature is 0±5℃, and the circulation volume of the solution circulating in the device is 2m.
It has been experimentally found that relatively good results can be obtained by setting the temperature to 3 and the circulation flow rate to 10 (/min).Temperature: 80
A crystallizer that satisfies the above setting conditions was attached to a neutralization tank containing a sodium hydroxide solution with a concentration of 25 wt% at ±5°C, and when the sodium nitrate concentration in the neutralization tank was lowered, sodium nitrate crystallized. The amount of analysis was 40.5 kg/hr. In addition, the sodium nitrate concentration in the neutralization tank is 200±2
It was maintained at 0g/J2 (80±5°C). The sodium nitrate concentration in the neutralization tank when a crystallizer is not installed is 40
0±50 g/β (80±5° C.), indicating that the sodium nitrate concentration is maintained at a fairly low concentration using the crystallization method.

Next, a method for reducing the concentration of nitrates in the primary washing tank will be explained. In this embodiment, a filtration device and a diaphragm electrolyzer are attached to the primary washing tank, and the washing liquid in the primary washing tank is circulated between these devices. In order to prevent clogging of the ion exchange membrane used in the diaphragm electrolyzer, a washing liquid is first introduced into a filtration device to remove particles such as heavy metal compounds contained in the washing liquid. The filtered alkaline aqueous solution is caused to flow into the diaphragm electrolyzer, and nitrate ions and sodium ions are separated by electrolysis. FIG. 2 is an example of a novel diaphragm electrolysis device that can be used in this example.

In FIG. 2, reference numeral 1 denotes an electrolytic cell, and this electrolytic cell is divided into cathode chambers 5, 9, stock solution chambers 6, 8, and anode chamber 7 by ion exchange membranes 2a to 2d consisting only of anion exchange membranes. A stainless steel cathode plate 10.1 is provided in the cathode chambers 5 and 9.
2 are arranged respectively, and the chamber is filled with an alkaline hydroxide solution of a predetermined concentration. A platinum-plated titanium anode plate 11 is placed in the anode chamber 7, and the chamber is filled with a nitric acid solution of a predetermined concentration.

Hereinafter, an example will be explained in which the nitrate is sodium nitrate. The filtered washing liquid flows into the stock solution chambers 6 and 8 from the stock solution inlets 3b and 3d, respectively.

When a predetermined amount of current flows through the cathode plates 10, 12 and the anode plate 11, the sodium nitrate in the washing liquid in the stock solution chambers 6, 8 is decomposed into sodium ions and nitric acid ions. Further, the sodium hydroxide in the cathode chamber 5.9 is decomposed into sodium ions and hydroxide ions. Nitrate ions in the stock solution chambers 6 and 8 pass through the anion exchange membranes 2b and 2c, enter the anode chamber 7, and become nitric acid in the anode chamber 7. Further, the hydroxide ions in the cathode chamber 5.9 pass through the anion exchange membranes 2a and 2d and pass through the stock solution chamber 6.9.
8 and combines with sodium ions in the stock solution chambers 6 and 8 to become sodium hydroxide. The generated water containing sodium hydroxide is discharged from the raw solution discharge ports 4b and 4d. The discharged water is returned to the primary washing tank for reuse. When electrolysis is performed in this device, the movement of nitrate ions in the stock solution chambers 6 and 8 to the cathode chamber is suppressed by the action of the electric field and the separation of the cathode and stock solution chambers.

Further, the movement of sodium ions in the stock solution chambers 6 and 8 to the cathode chamber is suppressed by the anion exchange membranes 2a and 2d. Furthermore, in the cathode chamber 5.9, in order to keep the concentration of sodium hydroxide in the chamber constant, a catholyte inlet 3 is provided.
Water is injected from ports a and 3e, and a sodium hydroxide solution of a certain concentration is discharged from catholyte outlets 4a and 4e. On the other hand, in the anode chamber 7, water is injected from the anolyte inlet 3c to keep the nitrate concentration in the room constant.
A constant concentration of nitric acid solution is discharged from the

When the diaphragm electrolyzer equipped with the anion exchange membrane shown in FIG. 2 is used, alkali ions cannot be recovered from the washing liquid. Therefore, after a certain period of time, the pH in the washing liquid increases and it becomes necessary to replace the washing liquid. Therefore, if a diaphragm electrolysis device in which the anion exchange membrane of the device shown in Figure 2 is replaced with a cation exchange membrane is connected in series to a diaphragm electrolysis device equipped with an anion exchange membrane, alkali ions can be recovered from the washing liquid. The pH of the washing liquid can be controlled appropriately. A device equipped with an anion exchange membrane,
An example will be described in which a composite device is used in which a device equipped with a cation exchange membrane is combined in series. The explanation of the device equipped with an anion exchange membrane is omitted as it is as explained above.Here, the device equipped with a cation exchange membrane is designated by the reference numerals in Figure 2, and the nitrate is replaced with sodium nitrate. This will be explained using a case as an example. In this composite device, the stock solution outlet of the device equipped with the anion exchange membrane is directly connected to the stock solution inlet of the device equipped with the cation exchange membrane. Therefore, the stock solution chambers 6 and 8 of the device equipped with a cation exchange membrane contain a small amount of nitrate that could not be decomposed and removed by the device equipped with an anion exchange membrane, as well as the sodium hydroxide produced in the device. A washing liquid containing water is flowing in. The sodium ions decomposed in the stock solution chambers 6 and 8 are transferred to the cation exchange membrane 2a.
, 2d and enters the cathode chamber 5.9, where it becomes sodium hydroxide and is recovered. Further, nitric acid in the anode chamber 7 is decomposed into hydrogen ions and nitrate ions, and the hydrogen ions are transferred to the cation exchange membrane 2b.

2C, enters the stock solution chamber 6.8, and combines with hydroxyl ions in the stock solution chamber to become water. The water produced in the stock solution chamber is
Together with the washing liquid, there is an undiluted solution outlet 4b.

It is discharged from 4d. The discharged washing liquid is returned to the hot water washing tank for reuse. When electrolysis is performed in a device equipped with a cation exchange membrane, the movement of nitrate ions in the stock solution chamber 6.8 to the cathode chamber is suppressed by the action of the electric field and the cation exchange membranes 2a and 2d. No reaction intermediates are produced on the cathode plate. Further, similar to the device equipped with an anion exchange membrane, a catholyte inlet 3a is provided to keep the concentration of sodium hydroxide in the cathode chambers 5 and 9 constant.

Water is injected from 3e, and a sodium hydroxide solution of a certain concentration is discharged from catholyte outflow ports 4a and 4e. On the other hand, in the anode chamber 7, water is injected from the anolyte inlet 3C to keep the nitric acid concentration in the room constant, and a nitric acid solution with a constant concentration is discharged from the anolyte outlet 4C.

In a composite device configured in this manner, the side diaphragm electrolyzer may be operated at all times, but even if there is sodium hydroxide in the washing liquid, there will be no particular problem with washing as long as the amount does not increase to a certain extent. .

Therefore, in order to increase operational efficiency, the diaphragm electrolyzer equipped with a cation exchange membrane is operated when the pH concentration of the washing liquid exceeds a predetermined value, and the operation is stopped when the pH concentration becomes neutral. The pH concentration of the washing liquid may be appropriately controlled. Therefore, the nitrate concentration in the primary washing tank was reduced using a composite device designed to operate a diaphragm electrolyzer equipped with a cation exchange membrane only when the pH of the washing liquid reached 13 or higher. The experimental data is shown below. - For example, the washing liquid circulation rate is 2J2/min.

A primary washing tank with a sodium hydroxide concentration of 1.2wj%, a nitrate concentration of Q, and a 9wj% concentration was prepared using a composite device in which the current density was set to IOA/dm2 and the membrane area of the ion exchange membrane was set to 53dm2. I tried lowering the nitrate concentration in the washing fluid. When operated for 10 days under these set conditions, 2.5 kg/day of nitrate ions could be separated and removed. This result shows that the device operates with a high dialysis current efficiency of about 80%. Furthermore, when a device with twice the capacity of the combined device was manufactured and operated under the same conditions, it was possible to separate and remove nitrate ions dissolved in the primary washing tank at a rate of about 4.5 kg/day. This result shows that the amount of nitrate ions dissolved in the primary washing tank is approximately 1.
This shows that 00% removal was possible.

When the nitrate concentration in the washing tank is reduced using the diaphragm electrolyzer of this example, reaction intermediates are generated on the cathode plate during electrolysis because the exchange membrane separates the anode chamber, stock solution chamber, and cathode chamber. Corrosion of the electrodes and mixing of reaction intermediates into the washing liquid can be prevented.

Further, washing can be performed without replacing the washing liquid in the washing tank which does not drain water.

FIG. 3 shows another diaphragm electrolyzer that can be used in embodiments of the invention. Since the structure of this device is well known, it will be briefly explained below. In FIG. 3, 13 is an electrolytic cell, and the electrolytic cell 13 is divided into a cathode chamber 15 and an anode chamber 16 by an anion exchange membrane 14. Cathode chamber 15
A cathode plate 17 is disposed in the chamber, and an anode plate 18 is disposed in the anode chamber 16.
is installed. The washing liquid after filtration is sent to the catholyte inlet 19
It flows into the cathode chamber 15 from there and is returned to the primary washing tank from the outlet 20. Since a predetermined amount of current is passed through the anode plate 18 and the cathode plate 17, nitrates in the washing liquid in the cathode chamber 15 are decomposed by electrolysis.

If the nitrate is sodium nitrate, the sodium nitrate is decomposed into sodium ions and nitrate ions, and the nitrate ions pass through the anion exchange membrane 14 and enter the anode chamber 16, where they become nitric acid. Further, the sodium ions in the cathode chamber 15 turn into sodium hydroxide, and the washing liquid containing sodium nitrate is discharged from the catholyte outlet 20. The discharged washing liquid is returned to the washing tank. Also, anode chamber 1
6, water is injected from the anolyte inlet 21 to prevent the nitric acid concentration from increasing, and nitric acid with a constant concentration is discharged from the anolyte outlet 22. The discharged nitric acid dissolves metals such as nickel and cadmium to form nitrates, which can be reused in the impregnation process.

In this diaphragm electrolyzer, since the cathode is disposed in the washing liquid containing nitrate ions, the nitrate ions are reduced at the cathode and a reaction intermediate (NH20H) is generated. Therefore, compared to the diaphragm electrolyzer shown in FIG. 2, corrosion of the cathode and mixing of reaction intermediates into the washing solution cannot be ignored.

In the above example, two washing steps were provided, and the nitrate concentration in the washing tank in the first washing step was reduced by diaphragm electrolysis, but the method for reducing the nitrate concentration and the number of washing tanks for reducing the nitrate concentration are Optional.

[Effect of the invention] According to the invention of claim 1, when the concentration of nitrate is reduced in the neutralization tank and at least in the first washing tank of at least two washing tanks, the nitrate concentration is reduced from the neutralization tank. In addition to reducing the amount of nitrate adhering to the substrate being washed, the amount of nitrate washed away into the first washing tank can be reduced. Therefore, according to the present invention, the amount of nitrogen-containing compounds in the waste liquid can be reduced compared to the conventional method, and even if the waste water is discharged as it is, eutrophication of rivers can be suppressed.

Further, as in the invention of claim 2, if the washing tank for reducing the nitrate concentration is a washing tank that does not substantially drain water, the waste liquid discharged outside the factory will be used to clean the substrates that have been washed in the first washing tank. Since only the wastewater is discharged from the immersion washing tank, the amount of nitrogen-containing compounds in the wastewater discharged into rivers, etc. is small, and eutrophication of rivers can be reliably prevented.

Furthermore, as in the invention of claim 3, the nitrate concentration of the alkaline aqueous solution in the neutralization tank is reduced by a crystallization method, and the nitrate concentration in the washing tank in which water washing is performed at least first is reduced by a diaphragm electrolysis method. , the nitrate concentration in the first flushing tank can be significantly reduced with lower operating costs.

Furthermore, when the nitrate concentration in the washing tank is reduced using a diaphragm electrolyzer in which the anode chamber, stock solution chamber, and cathode chamber are separated only by an anion exchange membrane as in the invention of claim 4, the reaction is intermediated at the cathode plate. No substances are generated, and corrosion of the cathode plate can be prevented.

Furthermore, as in the invention of claim 5, there is provided a diaphragm electrolyzer comprising an anode chamber, an undiluted solution chamber and a cathode chamber, each of which is separated only by an anion exchange membrane, and an anode chamber, an undiluted solution chamber and a cathode chamber. By using a composite device in which the above-mentioned chambers are combined in series with a diaphragm electrolyzer in which each chamber is separated only by a cation exchange membrane, alkali ions can be recovered to reliably reduce the nitrate concentration in the washing liquid. Moreover, there is an advantage that the pH of the washing liquid can be appropriately controlled. Therefore, even if this rinsing liquid is returned to the rinsing tank in which rinsing is first performed, electrode plates for alkaline storage batteries can be manufactured over a long period of time.

[Brief explanation of drawings]

Fig. 1 is a manufacturing process diagram of a method for producing electrode plates for alkaline storage batteries showing an embodiment of the present invention, Fig. 2 is a schematic configuration diagram of an example of a diaphragm electrolyzer used in the embodiment, and Fig. 3 is an embodiment. FIG. 4 is a schematic diagram of another diaphragm electrolyzer used in the present invention, and FIG. 4 is a manufacturing process diagram of a conventional method for manufacturing electrode plates for alkaline storage batteries. 1... Electrolytic layer, 2a to 2d... Ion exchange membrane, 3a
. 3e...Cathode solution inlet, 3b, 3d...Natural solution inlet, 3c...Anolyte inlet, 4a, 4e...Cathode solution outlet, 4b, 4d...Natural solution outlet, 4c ...Anolyte outflow port, 5.9...Cathode chamber, 6.8...Standard solution chamber, 7
... Anode chamber, 10.12... Cathode plate, 11... Anode plate, 13... Electrolyte layer, 14... Anion exchange membrane,
15...Cathode chamber, 16°...Anode chamber, 17...Cathode plate, 18...Anode plate, 19...Catholyte inlet, 20
...Catholyte outflow port, 21...Anolyte inflow port, 22.
...Anolyte outflow port. Figure 1

Claims (5)

[Claims] (1) The substrate impregnated with nitrate is immersed in a neutralization tank containing an aqueous alkali hydroxide solution to turn the nitrate into an active material, and then the substrate is immersed in at least two water washing tanks to be washed with water and alkali In the method of manufacturing electrode plates for storage batteries, the nitrate concentration in the neutralization tank and in at least the first washing tank of the at least two washing tanks is reduced by using a crystallization method or an electrolytic method. A method of manufacturing an electrode plate for an alkaline storage battery, characterized by: (2) The method for producing an electrode plate for an alkaline storage battery according to claim 1, wherein the washing tank for reducing the nitrate concentration is a washing tank that does not substantially drain water. (3) A claim characterized in that the nitrate concentration in the neutralization tank is reduced by a crystallization method, and the nitrate concentration in the washing tank in which water washing is performed at least first is reduced by using a diaphragm electrolysis method. Item 2. A method for producing an electrode plate for an alkaline storage battery according to item 1 or 2. (4) A claim characterized in that the diaphragm electrolysis method is carried out using a diaphragm electrolysis device that is equipped with an anode chamber, a stock solution chamber, and a cathode chamber, and each of the chambers is separated only by an anion exchange membrane. Item 3. A method for producing an electrode plate for an alkaline storage battery according to item 3. (5) The diaphragm electrolysis method includes a diaphragm electrolysis device that is equipped with an anode chamber, a stock solution chamber, and a cathode chamber, each of which is separated only by an anion exchange membrane; The electrode plate for an alkaline storage battery according to claim 3, characterized in that the electrode plate for an alkaline storage battery is carried out using a composite device in which a diaphragm electrolyzer and a diaphragm electrolyzer in which each chamber is separated only by a cation exchange membrane are combined in series. manufacturing method.