JP2002220220A - Method for producing alkali-free water glass solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dealkalized water glass solution which can be suitably used as a soil improvement material by de-alkaliizing a water glass solution by an ion exchange membrane electrodialysis method. Provided is a method capable of performing electrodialysis stably for a long time without causing scale to adhere to the surface of the product. SOLUTION: A cation exchange membrane and an anion exchange membrane are alternately arranged between an anode and a cathode, and a desalination chamber in which an anode side and a cathode side are separated by an anion exchange membrane and a cation exchange membrane, respectively. And an electrodialysis apparatus in which a concentration chamber partitioned on the anode side and the cathode side by a cation exchange membrane and an anion exchange membrane, respectively, is alternately formed, and a water glass solution is supplied to the desalting chamber to perform electrodialysis. In a method for producing a dealkalized water glass solution, a metal ion other than sodium, potassium, lithium, iron, aluminum, and titanium contained in the water glass solution and the concentrate used is 10 p.
Perform electrodialysis at pm or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a dealkalized water glass solution useful as a soil injection agent.

[0002]

2. Description of the Related Art In civil engineering work, a chemical solution injection method for improving a ground by injecting a ground improvement material from the outside into a ground which may be collapsed due to excavation or a ground which is difficult to excavate due to spring water or the like is used. It is widely used.

[0003] Various types of soil improvement materials currently used are known, but a ground injection material mainly composed of water glass is inexpensive and the gel time can be easily adjusted.

Recently, a silica sol-based ground containing water glass as a main component has been developed because the solidified product obtained by injection has a high strength and is excellent in durability, and the injection solution is a single solution, the gel time is easily adjusted, and the handling is easy. Improved injection materials are often used.

[0005] However, the silica sol-based ground improvement injection material contains a large amount of alkali metal salts, and the strength of the solidified body obtained by using the non-alkali-based ground improvement injection material decreases, In addition, there is a problem that the alkali or salt is released or deviates from the compacted body, and the compacted body shrinks to reduce its durability.

In order to improve such disadvantages, a method of removing alkali from water glass by an ion exchange resin method has been adopted (JP-A-11-279552).

However dealkalization treatment by ion exchange resin method is prolonged dealkalization requires a regeneration of the resin is impossible, even higher water glass with or SiO ₂ concentrations that play effluent is discharged Since gelation occurs near the resin, the conditions used are restricted.

Therefore, recently, a method has been adopted in which water glass is dealkalized by an ion exchange membrane method electrodialysis apparatus (Japanese Patent Application Laid-Open No. 11-61124). In the method,
An electrolytic dialysis tank, a pair of anodes and cathodes respectively disposed on opposite end faces inside the tank, an anion exchange membrane on the most anode side between these positive and negative electrodes, and a cation exchange membrane on the most cathode side. The membrane comprises positive and anion exchange membranes, each of which is arranged alternately and so as to form a plurality of compartments, of which the compartments where the anode and the cathode are located are filled with water. At the same time, the other compartments are alternately filled with water as a raw material and water as a concentrate, and a current is passed between the positive and negative electrodes, whereby Na ⁺ ions in the water glass solution undergo cation exchange. The OH ^- ions are permeated and released through the membrane into the water filled in one adjacent compartment through the membrane, and the OH ^- ions are introduced into the water filled in the other adjacent compartment through the anion exchange membrane. Through the membrane Then, the water glass solution is subjected to a dealkalization treatment to obtain a dealkalized water glass solution.

[0009]

However, when the above method was carried out, it was found that as the dialysis time passed, scale adhered to the surface of the ion exchange membrane, and electrodialysis could not be continued.

Accordingly, the present invention provides a method for producing a de-alkali water glass solution by an ion exchange membrane electrodialysis method, in which the scale is prevented from adhering to the surface of the ion exchange membrane and electrodialysis is stably continued for a long time. The aim is to provide a method that is possible.

[0011]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors analyzed the attached scale and studied a method for preventing the attached scale. As a result, the main component of the scale is a silicate containing calcium and magnesium, and the concentration of metal ions other than sodium, potassium, lithium, iron, aluminum, and titanium contained in the water glass solution and the concentrate used is 2 ppm. When supplied in the following manner, it has been found that the generation of scale is suppressed. Further, based on the findings, further investigations revealed that the scale was generated in electrodialysis by sodium, potassium, lithium, iron, aluminum contained in the water glass solution and the concentrated solution.
In addition, when the amount of metal ions other than sodium and the like is greatly reduced to 10 ppm or less, the adhesion of scale is effectively suppressed, and stable continuous operation is performed. The inventors have found that the present invention can be performed, and have completed the present invention.

That is, according to the present invention, a cation exchange membrane and an anion exchange membrane are alternately arranged between an anode and a cathode, and the anode side and the cathode side are separated by an anion exchange membrane and a cation exchange membrane, respectively. Using an electrodialysis apparatus in which a concentrated desalting chamber, and an enrichment chamber in which an anode side and a cathode side are separated by a cation exchange membrane and an anion exchange membrane, respectively, are alternately formed, a water glass solution is supplied to the desalination chamber. In a method for producing a dealkalized water glass solution by supplying a concentrated solution composed of an aqueous solution of an electrolyte to the concentrating chamber and producing a dealkalized water glass solution, sodium, potassium, lithium contained in the water glass solution and the concentrated solution used, A method for producing a dealkalized water glass solution, characterized in that the ion concentration of metals other than iron, aluminum and titanium is 10 ppm or less.

[0013] Among the metal ions other than sodium, potassium, lithium, iron, aluminum and titanium, calcium ions and magnesium ions are liable to be scaled due to their low solubility when silicate is formed. It is preferable to use a water glass solution and a concentrated solution having a total concentration of calcium ions and magnesium ions of 10 ppm or less, particularly 2 ppm or less.

According to the production method of the present invention, electrodialysis can be continued continuously for a long time and stably, and it is possible to efficiently produce a dealkalized water glass solution.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In the production method of the present invention, the concentration of each metal ion other than sodium, potassium, lithium, iron, aluminum and titanium contained in a water glass solution and a concentrated solution to be used is reduced to 10 ppm or less. Other than this, there is no particular difference from the conventional method of desalting a water glass aqueous solution by electrodialysis.

That is, as an electrodialysis apparatus, for example, a cation exchange membrane (hereinafter also referred to as a CE membrane) and an anion exchange between an anode and a cathode as disclosed in Japanese Patent Application Laid-Open No. 11-61124. Film (hereinafter also referred to as AE film)
Are alternately positioned, and the anode side is an anion exchange membrane (AE membrane)
And a concentrator separated by a cation exchange membrane (CE membrane) on the cathode side and by a cation exchange membrane (CE membrane) on the anode side and by an anion exchange membrane (AE membrane) on the cathode side. An electrodialyzer with alternating chambers can be used without any restrictions.

As for the electrodes and the respective ion exchange membranes required for constituting the above-mentioned apparatus, those used in the conventional electrodialysis apparatus are not particularly limited and used.

That is, as the anode and the cathode used in the present invention, electrodes used in the electrochemical industry such as water electrolysis and salt electrolysis are used without limitation. For example, as the anode material, nickel, iron, lead, titanium, platinum, graphite, etc.,
As the cathode material, nickel, iron, stainless steel, platinum, titanium and the like are preferably used.

The anion exchange membrane (AE) used in the present invention
The membrane is not particularly limited as long as it is a membrane having selective anion permeability made of a resin to which an anion exchange group is bonded, and a known anion exchange membrane can be used. As the anion exchange group,
Functional groups that can be positively charged in an aqueous solution can be employed without particular limitation. Specific examples include primary to tertiary amino groups, pyridyl groups, quaternary ammonium bases, quaternary pyridinium bases, and mixtures of these ion exchange groups. The AE membrane can be used regardless of whether it is a polymerization type, a condensation type, a homogeneous type, a heterogeneous type, etc. Further, the presence or absence of a reinforcing material used for reinforcement and the material of the resin to which the ion exchange group is bonded (Usually, a hydrocarbon resin or a fluorine resin is used) is not particularly limited. In the production method of the present invention, since an alkaline solution such as a water glass solution and a sodium hydroxide solution is used, it is desirable to use an alkali-resistant AE film.

The cation exchange membrane (CE) used in the present invention
The membrane is not particularly limited as long as it is a membrane having cation selective permeability composed of a resin to which cation exchange groups are bonded, and a known cation exchange membrane can be used. As the cation exchange group, a functional group that can be negatively charged in an aqueous solution can be employed without particular limitation. Specific examples include a sulfonic acid group, a carboxylic acid group, a phosphonic acid group, a sulfate group, a phosphate group, and a mixture of these ion exchange groups. As the CE membrane, it can be used regardless of whether it is a polymerization type, a condensation type, a homogeneous type, a heterogeneous type, etc. Further, the presence or absence of a reinforcing material used for reinforcement, and the material of the resin to which the ion exchange group is bonded (Usually, a hydrocarbon resin or a fluorine resin is used) is not particularly limited.
In the production method of the present invention, since an alkaline solution such as a water glass solution and a sodium hydroxide solution is used, it is preferable to use an alkali-resistant CE film.

In the electrodialysis apparatus used in the present invention, an AE membrane and a CE membrane are alternately arranged between an anode and a cathode which are arranged so as to face each other, so that the AE membrane and the anode side are respectively AE membranes. And a CE membrane (that is, the AE membrane is on the anode side and the CE membrane is on the cathode side), and the anode and cathode sides are adjacent to the desalination chamber, respectively. (Ie, the membrane on the anode side is a CE membrane, and the membrane on the cathode side is an AE membrane).
And a concentration chamber (which is a membrane). Hereinafter, the configuration of the electrodialysis apparatus used in the present invention will be specifically described using the electrodialysis apparatus 1 shown in FIG. In the electrodialysis apparatus 1 shown in FIG. 1, a CE membrane 5 is arranged between an anode 2 and a cathode 3 which are arranged so as to face each other in order from the anode side.
And the AE membrane 4 are alternately arranged so that the most cathode side becomes the CE membrane 5, thereby forming an anode chamber 6, a cathode chamber 7, a desalination chamber 8, and a concentration chamber 9.

Here, the desalting chamber means that when an aqueous solution of a salt is supplied to the chamber during electrodialysis, anions derived from the salt permeate and diffuse through the AE membrane on the anode side,
This means a room in which cations derived from salts diffuse through the CE membrane on the cathode side, and as a result, the salt concentration in the room is reduced. Further, in the concentration chamber, the salt-derived anions and cations supplied from the AE membrane and the CE membrane to the adjacent desalination chambers respectively when the electrodialysis was performed in the same manner permeate through each membrane and flow in. Means a room where the salt concentration in the room increases. Therefore, in the production method of the present invention,
A raw water glass aqueous solution is supplied to the desalting chamber, and a concentrated solution comprising an aqueous electrolyte solution such as an aqueous sodium hydroxide solution is supplied to the concentrating chamber to perform electrodialysis. The existing Na ⁺ ions permeate through the CE membrane and diffuse through the CE membrane to the adjacent concentration chamber, and the OH ⁻ ions also present in the water glass solution permeate through the AE membrane and pass through the AE membrane. And diffused into the adjacent concentrating chamber, and as a result, a water glass aqueous solution having a reduced alkali concentration in the water glass solution can be obtained. At this time, in the concentration chamber, Na diffused from the desalination chambers on both sides is used.
^{The +} ions OH ^- ions are confined, and an aqueous sodium hydroxide solution having an increased concentration is obtained.

FIG. 1 shows a case in which a plurality of desalting chambers and a plurality of concentrating chambers are respectively formed.
It may be. However, in the case of performing on an industrial scale, from the viewpoint of production efficiency, the arrangement of the membranes in the electrodialyzer is anode-CE membrane- (AE membrane-CE membrane) _n -cathode (where n is It is preferable that n is 5 to 200 when the number of repetitions of the arrangement of the AE film and the CE film. In particular, a so-called filter press type structure is provided in which the respective membranes are arranged so as to be in the preferable range of n described above through a chamber frame having a cutout portion at the center for forming each chamber and tightened from both ends. Is preferred.

Each chamber is provided with a spacer for securing a flow path and a distribution plate for evenly distributing the liquid. The shape of the spacer and the distribution plate is as follows.
Although not particularly limited, it is preferable to use a structure having an effect of preventing scale generation and capable of easily removing scale even if it occurs, for example, a tunnel type structure.

In the production method of the present invention, electrodialysis is performed by supplying a water glass solution as a raw material to the above-mentioned desalting chamber. At this time, sodium contained in the water glass solution used and the concentrated solution are used. It is necessary to keep the concentration of metal ions other than potassium, lithium, iron, aluminum and titanium at 10 ppm or less. Sodium, potassium, lithium,
Concentration of metal ions other than iron, aluminum and titanium is 10p
When the pressure is higher than pm, scale deposition occurs with the elapse of operation time and this adheres to the ion-exchange membrane surface, making it difficult to supply raw materials or increasing membrane resistance in a relatively short period of time, resulting in long-term stability. Operation is not possible. From the viewpoint of scale generation prevention effect, sodium, potassium, lithium, iron, aluminum, contained in the water glass solution and the concentrated solution,
Preferably, the concentration of each metal ion other than titanium and titanium is 2 ppm or less, or the total concentration is 10 ppm or less. Further, the total concentration of calcium ions and magnesium ions, which is particularly likely to cause scale generation, is 10 pp.
m or less, more preferably 2 ppm or less.

The water glass solution used in the production method of the present invention is an aqueous solution of an alkali silicate obtained by melting silicon dioxide and an alkali, wherein the concentration of each metal ion other than sodium is 10 ppm or less. The water glass having a high silica (SiO ₂ ) concentration is diluted with water from which metal ions other than alkali metal ions have been removed so that the silica (SiO ₂ ) concentration is 3 to 8 watts.
It is preferable to use those adjusted to t%, especially 5 to 7 wt%. As the water glass having a high silica (SiO ₂ ) concentration, JIS standard No. 3 water glass (silica concentration: 28 to 30% by weight) is preferably used because it is industrially available. The concentration of metal ions other than sodium, potassium, lithium, iron, aluminum, and titanium contained in the JIS No. 3 water glass varies depending on the product, but the concentration is usually 50 ppm or less. By diluting 5 times or more with water not containing, a water glass aqueous solution having a desired concentration can be obtained. In addition, since the composition of the commercially available JIS standard No. 3 water glass has been analyzed and its composition has been clarified, sodium, potassium, lithium, iron, aluminum,
It is preferable to obtain and use those having a low concentration of metal ions other than titanium.

The method for preparing the water used for the above-mentioned dilution is not particularly limited. In general, tap water is prepared by a known deionization method such as an ion exchange resin method, a reverse osmosis membrane method, a distillation method, and an electrodialysis method. It can be easily adjusted by removing metal ions other than alkali metal ions. For example, raw water such as tap water may be supplied to a resin tower filled with a sodium-type ion exchange resin, and metal ions such as calcium and magnesium contained in the raw water may be replaced with sodium ions. At this time, if the continuous operation is performed, the ion exchange capacity of the ion exchange resin decreases with time, so it is preferable to appropriately perform a regeneration treatment. The regeneration treatment may be performed by introducing salt water (such as saline) into the ion exchange resin from a salt water tank provided separately from the resin tower to regenerate the resin.

The concentrated liquid used in the production method of the present invention is an aqueous solution of an electrolyte having a metal ion concentration other than sodium, potassium, lithium, iron, aluminum and titanium of 1%.
It is not particularly limited as long as it is 0 ppm or less,
A waste liquid consisting of a concentrated aqueous alkali hydroxide solution by-produced during production can be effectively used, and the concentrated aqueous alkali hydroxide solution is sodium, potassium, from the viewpoint of increasing production efficiency.
It is preferable to use those prepared by diluting with water from which metal ions other than lithium, iron, aluminum and titanium have been removed. As the dilution water, the same dilution water as described above may be used.

Hereinafter, the procedure including electrodialysis conditions and the like will be described in detail by taking as an example a case where a dealkalized water glass solution is continuously produced by the above system.

In the electrodialysis apparatus 1 shown in FIG. 1, as described above, the anion exchange membranes 4 and the cation exchange membranes 5 are alternately arranged between the anode 2 and the cathode 3, and the anode compartment 6 , A cathode chamber 7, a desalting chamber 8, and a concentrating chamber 9. Each chamber frame is provided with a liquid supply port and a liquid discharge port, and each liquid supply port and the liquid discharge port are connected to a main pipe via a branch pipe as necessary. Further, it is general to provide a spacer having a flow distribution function for keeping the thickness of the chamber frame uniform and making the flow of the supplied liquid uniform within the chamber frame.

A source liquid supply passage 10 for supplying an aqueous solution of water glass as a source liquid is connected to the desalting chamber 8 so that the source liquid is continuously or intermittently supplied to the source liquid tank 18.
It can be supplied from. In the raw material liquid tank 18, the concentrated water glass supplied from the concentrated water glass tank 23 in the raw material liquid preparation tank 24 is mixed with soft water 2, which is water from which metal ions other than alkali metal ions have been removed.
The raw material liquid prepared by diluting and mixing with the soft water supplied from the soft water tank 22 storing the liquid 2 is supplied continuously or intermittently, and a part of the product liquid extracted from the electrodialysis tank is continuously supplied. It can be supplied periodically or intermittently. The soft water stored in the soft water tank 22 can be prepared by treating raw water (for example, tap water) 20 in an ion exchange resin tower 21. Further, an aqueous solution of sodium hydroxide, which is a concentrated solution, can be supplied to the concentration chamber 9 continuously or intermittently from a concentrated solution tank 19 through a concentrated solution supply passage 11. A part of the concentrated solution having the increased salt concentration is continuously or intermittently supplied from the electrodialysis tank to the concentrated liquid tank 19 and continuously or intermittently supplied from the soft water tank 22 to the appropriate concentration. Can be prepared. Further, a product liquid extraction passage 1 for continuously or intermittently extracting a part of the product liquid which is the “dealkalized raw material liquid” is provided in the desalting chamber 8.
2 are connected. Further, a concentrated liquid extraction passage 13 for continuously or intermittently extracting a part of the concentrated liquid having an increased salt concentration is connected to the concentration chamber. In addition, anode room 2
The anolyte supply path 14 and the catholyte supply path 15, and the anolyte extraction path 16 and the catholyte extraction path 17 are connected to the cathode chamber 3 and the cathode chamber 3, respectively. In addition to being able to supply, at the time of operation, water or an aqueous alkali solution is supplied continuously or intermittently so that a liquid having an increased alkali metal concentration can be extracted.

When performing electrodialysis, first, an anolyte, a catholyte, a raw material solution, and a concentrate are supplied to the anode chamber 6, the cathode chamber 7, the deionization chamber hydrogen 8, and the concentration chamber 9, respectively. Next, a voltage is applied between the anode and the cathode to start electrodialysis. The current density at this time is not particularly limited, but is generally 0 to 10 A / dm ² , particularly preferably 0 to 5 A / dm ² . During the electrodialysis, the raw material liquid and the concentrated liquid are supplied continuously or intermittently using the above-mentioned respective flow paths, and the desalted raw material liquid and the concentrated liquid having an increased salt concentration are continuously or intermittently supplied. You just have to pull it out. At this time, it is preferable to perform electrodialysis while stirring the solution in each chamber in order to prevent an increase in the electric resistance of each ion exchange membrane. As the means for stirring, it is preferable to circulate each liquid.For that purpose, a tank is provided for each type of liquid outside each chamber, and a pump or the like is used between each chamber and the external tank. It is preferred that the liquid is circulated. By adopting such a method, it is easy to control the desalting state of the product alkali-free water glass.

Although the mode of performing electrodialysis continuously or intermittently has been described above, electrodialysis can be performed in batches.

[0034]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 A water glass having the same basic structure as shown in FIG. 1 and having the specifications shown in Table 1 and manufactured by Tokuyama Corporation (TS2-10) was used. The solution was diluted with ion-exchanged water to supply a water glass solution having a SiO ₂ content adjusted to 6 wt% to a desalting chamber, and sodium hydroxide was diluted with ion-exchanged water to 0.5 (mol / L). The adjusted sodium hydroxide solution was supplied to a concentration chamber to perform a desalting treatment. However, the above electrodialysis conditions were performed until the conditions shown in Table 3 were obtained by batch processing under the starting conditions shown in Table 2. Table 4 shows the composition of the product solution (de-alkali solution) and the concentrate before and after dialysis. As shown in Table 4, the concentrations of calcium and magnesium contained in the dealkalized solution and the concentrated solution were 1.0 ppm and 0.8 ppm, and the total was 1.8 ppm. In addition, metal ions other than calcium, magnesium, sodium, potassium, lithium, iron, aluminum, and titanium were not detected, and 0 pp
m. The average current density during operation was 2.0 A /
dm ² , and the time required for dealkalization was 40 minutes. Further, after the operation, the dialysis tank was disassembled and inspected, but no scale was observed on the surface of the ion exchange membrane.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

[0039]

[Table 4]

Example 2 The procedure of Example 1 was repeated, except that a mixed solution of tap water and ion-exchanged water was used instead of ion-exchanged water when preparing the desalted solution and the concentrated solution. Electrodialysis. However, the above electrodialysis conditions were performed until the conditions shown in Table 3 were obtained by batch processing under the starting conditions shown in Table 2. Table 5 shows the composition of the dealkalized solution and the concentrated solution before and after dialysis. Here, the calcium and magnesium concentrations contained in the dealkalized solution and the concentrated solution were 6 pp
m and 2 ppm. Also, zinc is 0.1pp
m and copper were contained at 0.02 ppm. Metal ions other than calcium, magnesium, zinc, copper, sodium, potassium, lithium, iron, aluminum and titanium were not detected and were 0 ppm. The average current density during operation was 1.95 A / dm ² , and the time required for dealkalization was 42 minutes. After the operation, the dialysis tank was dismantled and inspected.
No scale was observed on the ion exchange membrane surface.

[0041]

[Table 5]

Comparative Example 1 In Example 1, when preparing the desalted solution and the concentrated solution,
Except for using tap water instead of ion exchange water,
Electrodialysis was performed in the same manner as in Example 1. However, the above
The analysis conditions were as follows:
The process was performed until the conditions shown in FIG. In addition, before and after dialysis
Table 6 shows the composition of the alkaline solution and the concentrated solution. Where
Calcium contained in alkaline solution and concentrate
The magnesium concentration was 20 ppm and 5 pp, respectively.
m. In addition, zinc is 0.2 ppm and copper is 0.05
ppm was contained. Calcium, magnesium, sub
Lead, copper, sodium, potassium, lithium, iron, al
No metal ions other than titanium and titanium are detected.
there were. The average current density during operation is 1.5 A / dm.
^TwoThe time required for dealkalization was 50 minutes. Further
In addition, as a result of dismantling inspection of the dialysis tank after operation, calcium
And magnesium-based scale ion exchange
It adhered to the film surface.

[0043]

[Table 6]

[0044]

According to the production method of the present invention, the water glass solution is dealkalized by an ion exchange membrane electrodialysis method to produce a dealkalized water glass solution which can be suitably used as a ground improvement material. Generation of scale containing calcium and magnesium as main components on the surface of the ion exchange membrane can be effectively suppressed. For this reason, it is possible to stably perform electrodialysis continuously for a long time.

Therefore, for example, in a method of producing dealkalized water glass on site and using it as a ground improvement material, the advantage of applying the production method of the present invention particularly when the method has a long term of construction is as follows. large.

[Brief description of the drawings]

FIG. 1 is a schematic view of a typical electrodialysis apparatus that can be used in the production method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electrodialysis apparatus 2 ... Anode 3 ... Cathode 4 ... Anion exchange membrane 5 ... Cation exchange membrane 6 ... Anode chamber 7 ... Cathode chamber 8 ... Desorption Salt room 9 ・ ・ ・ Concentration room 10 ・ ・ Material liquid supply path 11 ・ ・ Concentrate supply path 12 ・ ・ Production liquid discharge path 13 ・ ・ Concentrate discharge path 14 ・ ・ Anolyte supply path 15 ・ ・ Cathode supply path 16. Anolyte extraction path 17. Catholyte extraction path 18. Raw material liquid tank 19. Concentrate liquid tank 20. Raw water 21. Ion exchange resin tower 22. Soft water tank 23. Rich water glass tank 24. ..Material liquid preparation tank

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // E02D 3/12 101 E02D 3/12 101 C04B 111: 10 C04B 111: 10 C09K 103: 00 C09K 103: 00 F term (reference) 2D040 AA01 AA04 AB01 CA02 4D006 GA17 HA47 JA41A JA42A JA43A JA44A MA03 MA13 MA14 MB12 MC73 MC74 MC75 MC77 MC78 PB70 PC80 4G012 PB06 PC01 4G072 AA28 BB14 CC01 GG03 HH21 MM14 PP13 U30 CC

Claims (2)

[Claims] 1. A desalination wherein a cation exchange membrane and an anion exchange membrane are alternately arranged between an anode and a cathode, and the anode side and the cathode side are separated by an anion exchange membrane and a cation exchange membrane, respectively. A water glass solution is supplied to the desalting chamber by using an electrodialysis apparatus in which a chamber, and an enrichment chamber in which an anode side and a cathode side are separated by a cation exchange membrane and an anion exchange membrane, respectively, are alternately formed. In a method for producing a dealkalized water glass solution by supplying a concentrated solution comprising an aqueous solution of an electrolyte to perform electrodialysis, sodium, potassium, lithium contained in the water glass solution and the concentrated solution used,
Increase the ion concentration of metals other than iron, aluminum, and titanium to 10
A method for producing a dealkalized water glass solution, characterized in that the concentration is not more than ppm. 2. The method according to claim 1, wherein a water glass solution and a concentrated solution having a total concentration of calcium ions and magnesium ions of 10 ppm or less are used.