JP2003236345A - Method and apparatus for producing alkali-free water glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a desalting chamber during electrodialysis (and) when producing alkali-free water glass which can be suitably used as a ground improvement material by de-alkaliizing water glass by an ion exchange membrane electrodialysis method. Provided is a method and an apparatus capable of performing electrodialysis stably for a long time without generating a precipitate containing silicate as a main component in a concentration chamber. 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 the anode side and the cathode side are separated by an anion exchange membrane and a cation exchange membrane, respectively. The electrodialysis is performed by circulating and supplying water glass to the desalting chamber, using an electrodialysis apparatus in which an anode chamber and a cathode side are alternately formed with a concentration chamber partitioned by a cation exchange membrane and an anion exchange membrane, respectively. In the method for producing alkali-free water glass, the alkali-free water glass is produced while removing precipitates present in the circulated water glass by solid-liquid separation means such as a filter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing dealkalized water glass and a manufacturing apparatus therefor, which are useful as a ground injection material, a building material for which it is preferable to use water glass with a high molar ratio and an adhesive material, and a raw material for silica production. Regarding

[0002]

2. Description of the Related Art In civil engineering work, a chemical solution injection method is used to improve the ground by injecting a ground improvement material from the outside into the ground that may collapse due to excavation, etc., or the ground that is difficult to excavate due to spring water, etc. It is commonly used. There are various known ground improvement materials currently used, but recently, the strength of the solidified material by injection is high and its durability is excellent, and the injection liquid is one liquid and the gel time can be easily adjusted for easy handling. Because of their convenience, silica sol-based ground improvement injection materials, which are mainly composed of water glass, are often used.

However, this silica sol-based ground improvement injecting material contains a large amount of alkali metal salts, which may cause the strength of the obtained solidified body to decrease, and the alkali from the solidified body may increase over time. Alternatively, there is a problem that the salt is liberated or desorbed, and the solidified body shrinks to lower its durability. In order to improve such a defect, a method of removing an alkali content of water glass by an ion exchange resin method has been adopted (JP-A No. 11-279552). However, the dealkalization treatment by the ion-exchange resin method requires regeneration of the resin, so that the dealkalization treatment for a long period of time is impossible, and further, waste liquid for regeneration is discharged or SiO 2 is discharged.
₂ Water glass with high concentration gels in the vicinity of the resin, so there are restrictions on the conditions of use.

Therefore, recently, a method of dealkalizing water glass with an ion exchange membrane electrodialysis apparatus has been adopted (Japanese Patent Laid-Open No. 61-61124). In this method, an electrodialysis tank, a pair of an anode and a cathode respectively disposed on opposite end surfaces inside the tank, and an anion exchange membrane on the most anode side between these positive and negative electrodes and on the most cathode side. Comprises cation and anion exchange membranes in which cation exchange membranes are respectively located and are alternately arranged to form a plurality of compartments. Of these plurality of compartments, the compartment in which the anode and the cathode are located is By filling water and alternately filling water glass and water in the other compartments respectively, and passing an electric current between the positive and negative electrodes, Na ⁺ ions in the water glass are adjacent to each other through the cation exchange membrane. Is permeated and released through the membrane into the water filled in the compartment on one side, and OH ⁻ ions are released through the membrane into the water filled in the adjacent compartment on the other side through the anion exchange membrane, this Thus, the water glass is dealkalized to obtain dealkalized water glass.

[0005]

However, when the above-mentioned method was continuously carried out for a long period of time, it was found that the dealkalizing treatment capacity decreased with the passage of dialysis time. Therefore, the present invention, in a method of dealkalizing water glass by an ion exchange membrane electrodialysis device, to suppress the reduction of dealkalizing capacity, a method capable of stably continuing electrodialysis for a long time, The purpose is to provide.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems. As a result, the dealkalizing capacity decreases with the lapse of dialysis time because the deposit containing silicate as the main component adheres to the desalting chamber and the concentrating chamber, making it difficult to supply the raw material. I found that there is. And, in the case of circulating and supplying the raw material water glass to the desalting chamber, the precipitate deposited in the desalting chamber is present in the circulating water glass, and the precipitate present in the water glass It was found that the removal of the above can suppress the decrease in dealkalizing ability, and the electrodialysis can be continued stably for a long time, and the present invention has been completed.

That is, in 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 partitioned by the anion exchange membrane and the cation exchange membrane, respectively. Using an electrodialysis device in which the desalting chamber and the concentrating chamber in which the anode side and the cathode side are partitioned by the cation exchange membrane and the anion exchange membrane are alternately formed, water glass is circulated and supplied to the desalination chamber. In the method for producing dealkalized water glass by performing electrodialysis, a method for producing a dealkalized water glass solution is characterized in that precipitates existing in water glass to be circulated are removed.

In the present invention, (a) cation exchange membranes and anion exchange membranes are alternately arranged between the anode and the cathode, and the anode side and the cathode side are anion exchange membranes and cation exchange membranes, respectively. An electrodialysis tank in which a desalting chamber partitioned by a membrane and a concentrating chamber in which the anode side and the cathode side are respectively partitioned by a cation exchange membrane and an anion exchange membrane are formed, and (b) water glass supplied to the desalination chamber Water glass tank for storing water, a water glass supply channel for supplying water glass from the water glass tank to the desalination chamber, and demineralized water for returning water glass desalted in the desalination chamber to the water glass tank A process for producing dealkalized water glass having a water glass circulation path formed by a glass return path, characterized in that deposit removal means is installed in the water glass circulation path. Manufacturing equipment.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the manufacturing method and manufacturing apparatus of the present invention will be described. The production method of the present invention is the same as the conventional desalination method of water glass by electrodialysis except that the precipitates existing in the water glass which is circulated and supplied to the desalination chamber are removed. That is, as an electrodialysis device, a cation exchange membrane (hereinafter, also referred to as "CE membrane") and an anion exchange membrane between an anode and a cathode, as disclosed in, for example, Japanese Patent Laid-Open No. 11-61124. (Hereinafter, also referred to as “AE membrane”) are alternately arranged, and a desalting chamber in which the anode side and the cathode side are partitioned by an anion exchange membrane and a cation exchange membrane, respectively, and the anode side and the cathode side are cations, respectively. An electrodialysis device in which concentration chambers partitioned by an exchange membrane and an anion exchange membrane are alternately formed can be used without any limitation. Further, the electrodes and the respective ion-exchange membranes, which are the members necessary for constructing the device as described above, are those used in the conventional electrodialysis device without any particular limitation. That is, as the anode and cathode used in the present invention, electrodes used in the electrochemical industry such as water electrolysis and salt electrolysis can be used without limitation. For example, nickel, iron, lead, titanium, platinum, graphite, etc. are preferably used as the anode material, and nickel, iron, stainless steel, platinum, titanium, etc. are preferably used as the cathode material.

The anion exchange membrane (AE used in the present invention
The membrane is not particularly limited as long as it is a membrane composed of a resin having an anion exchange group bonded thereto and having an anion selective permeability, and a known anion exchange membrane can be used. As the anion exchange group, a functional group that can be positively charged in an aqueous solution can be used without particular limitation. Specifically, primary to tertiary amino group, pyridyl group, quaternary ammonium base, quaternary pyridinium base,
Furthermore, the thing in which these ion exchange groups were mixed is mentioned. As the AE membrane, it can be used without distinction of polymerization type, condensation type, homogeneous type, heterogeneous type, etc. Furthermore, the presence or absence of a reinforcing material used for reinforcement and the material of the resin to which the ion exchange group is bound. (A hydrocarbon resin or a fluorine resin is usually used) is not particularly limited. In the manufacturing method of the present invention, the liquid used is water glass, an alkaline solution such as an aqueous solution of sodium hydroxide,
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 composed of a resin having a cation exchange group bonded and having a cation selective permeability, 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 adopted without particular limitation. Specific examples thereof include a sulfonic acid group, a carboxylic acid group, a phosphonic acid group, a sulfuric acid ester group, a phosphoric acid ester group, and a mixture of these ion exchange groups. The CE membrane can be used without distinction of polymerization type, condensation type, homogeneous type, heterogeneous type, etc., and 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 bound. (A hydrocarbon resin or a fluorine resin is usually used) is not particularly limited.
In the manufacturing method of the present invention, since the liquid used is an alkaline solution such as water glass or an aqueous solution of sodium hydroxide, it is preferable to use an alkali-resistant CE film.

In the electrodialyzer used in the present invention, the AE film and the CE film are alternately arranged between the anode and the cathode arranged so as to face each other, and the AE film is provided on the anode side and the cathode side, respectively. And a deionization chamber partitioned by a CE film (that is, the diaphragm on the anode side is an AE film and the diaphragm on the cathode side is a CE film), and the anode side and the cathode side are respectively CE so as to be adjacent to the deionization chamber. Partitioned by membrane and AE membrane (that is, the diaphragm on the anode side is the CE membrane and the diaphragm on the cathode side is AE
And a concentrating chamber (which is a membrane) is formed.

A typical electrodialysis apparatus used in the present invention is shown in FIG. In the electrodialysis device 1 shown in FIG.
Between the anode 2 and the cathode 3 which are arranged so as to face each other, the CE films 5 and the AE films 4 are alternately arranged in order from the anode side, and the CE film 5 is closest to the cathode side. 6, a cathode chamber 7, a desalting chamber 8 and a concentrating chamber 9 are configured. A spacer for ensuring a flow path and a flow distribution plate for evenly distributing the liquid are provided in each chamber. The shape of these spacers and flow distribution plates is not particularly limited, but a structure having a precipitate generation preventing effect and capable of easily removing even if a precipitate is generated, for example, a tunnel type structure is used. It is preferably used.
Also, each chamber frame is provided with a liquid supply port and a liquid discharge port,
Each liquid supply port and liquid discharge port are connected to the main pipe via branch pipes as necessary.

A water glass supply passage 10 for supplying water glass as a raw material liquid is connected to the desalting chamber 8, and the water glass is continuously or intermittently stored in a water glass storage tank 18.
(The raw material water glass can be supplied to the storage tank through a line (not shown).). Further, the desalting chamber 8 is connected to a product liquid withdrawal path 12 for continuously or intermittently withdrawing all or part of the dealkaline (desalinized) water glass (that is, the product liquid). A part of the demineralized water glass is circulated to the water glass storage tank 18. A water glass circulation path is formed by the water glass supply path 10, the water glass storage tank 18, and the product liquid withdrawal path 12. Precipitates generated in the desalting chamber by electrodialysis flow out into the water glass circulation path along with the water glass circulated. In the water glass supply passage 10 between the water glass storage tank 18 and the electrodialysis tank 1, a water glass filter 2 is provided.
0 is connected to remove precipitates existing in the circulating water glass.

In desalination of water glass by electrodialysis, precipitates are mainly generated in the desalting chamber, but precipitates may also be generated in the concentration chamber. When the concentrated liquid is circulated and used, the precipitate generated in the concentrated chamber flows out from the concentrated chamber to the concentrated liquid circulation path. Therefore, it is preferable to remove the precipitates existing in the circulating concentrated solution in the same manner as the raw material water glass in order to carry out electrodialysis without increasing the membrane voltage.

FIG. 1 shows a mode of removing the deposits in the circulating concentrated liquid. A concentrated liquid containing an aqueous solution of an electrolyte such as sodium hydroxide is supplied to the concentrated chamber 9 through a concentrated liquid supply path 11 to a concentrated liquid storage tank 19 (in the storage tank, a fresh concentrated liquid by a line not shown or diluted water for concentration adjustment). Can be supplied continuously) or intermittently. The concentrate chamber is connected to a concentrate withdrawal path 13 for continuously or intermittently withdrawing all or part of the concentrate with increased salt concentration, and further concentrates part of the concentrate with increased salt concentration. It is circulated to the liquid storage tank 19. A concentrated liquid filter 21 is connected to the concentrated liquid supply path 11 between the concentrated liquid storage tank 19 and the electrodialysis tank 1 to remove precipitates existing in the concentrated liquid.

FIG. 1 shows an example in which the means for removing precipitates existing in the raw material water glass and the concentrated liquid are provided in the water glass supply passage 10 and the concentrated liquid supply passage 11, respectively. May be provided anywhere in the water glass circulation path and the concentrated liquid circulation path, respectively. The anode chamber 6 and the cathode chamber 7 have an anolyte supply path 14 and a catholyte supply path 15, respectively, and an anolyte withdrawal path 16 and a catholyte withdrawal path 1 respectively.
7 is connected so that an electrolytic solution (aqueous solution of electrolyte) as an anolyte solution and a catholyte solution can be supplied at the start of electrolysis, and at the time of operation, an electrolytic solution solution is continuously or intermittently supplied. The liquid with increased alkali concentration can be extracted.

Here, the desalting chamber means that when an aqueous salt solution is supplied to the chamber during electrodialysis, anions derived from the salt permeate and diffuse through the AE membrane on the anode side.
It means a chamber in which a cation derived from a salt permeates and diffuses through the CE film on the cathode side, and as a result, the salt concentration in the chamber decreases. In addition, the concentration chamber means that when electrodialysis is performed in the same manner, salt-derived anions and cations supplied from the AE membrane and the CE membrane to the adjacent desalting chambers permeate through the membranes, respectively. Means a chamber in which the salt concentration in the chamber increases.

Therefore, in the production method of the present invention, the raw water glass is supplied to the desalting chamber, and the concentrated liquid containing the electrolytic aqueous solution such as the alkaline hydroxide aqueous solution is supplied to the concentrating chamber to perform electrodialysis. Alkali metal ions such as Na ⁺ ions existing in the water glass supplied to the desalting chamber penetrate the CE film and diffuse into the adjacent concentrating chamber through the CE film, and also exist in the water glass. OH
^- ions are diffused into concentrating chamber passes through the AE film adjacent to each other via the AE film, resulting in alkali concentration of water in the glass can be obtained water glass drops. At this time, in the concentration chamber, Na ⁺ that has diffused from the desalting chambers on both sides is
Alkali metal ions such as ions and OH ⁻ ions are confined, and an alkali hydroxide aqueous solution having an increased concentration is obtained.

FIG. 1 shows a plurality of demineralizing chambers and concentrating chambers, each having one chamber.
May be However, in the case of carrying out on an industrial scale, from the viewpoint of production efficiency, the arrangement of the membranes in the electrodialyzer is as follows: anode-CE membrane- (AE membrane-CE membrane) _n -cathode (where n is It is preferable that n is 5 to 200 when the number is the repetition number of the arrangement of the AE film and the CE film. In particular, a so-called filter press type structure in which the respective membranes are arranged so as to be in the above-mentioned preferable range of n through a chamber frame having a notch for forming each chamber in the center and tightened from both ends Is preferred.

The method of desalting water glass using such an apparatus is not particularly different from the conventional method, and for example, the following method can be used. That is, when performing electrodialysis, first, the anolyte, the catholyte, and the concentrate, which consist of an aqueous solution of an electrolyte such as sodium hydroxide, are supplied to the anode chamber, the cathode chamber, and the concentrating chamber, respectively, and the desalting chamber is further fed with water. Water glass to be glass may be supplied, and then a voltage may be applied between the anode and the cathode to start electrodialysis.

At this time, the water glass used as a raw material is not particularly limited as long as it is an aqueous solution of an alkali metal silicate obtained by melting silicon dioxide and an alkali, but high silica (SiO ₂ ) is used because of easy preparation. water glass concentration is diluted with water, silica (SiO ₂₎ concentration of 3～8Wt%, it is preferable to particularly use those prepared in 5-7 wt-%.
As the water glass having a high silica (SiO ₂ ) concentration, it is preferable to use JIS standard No. 3 water glass (silica concentration 28 to 30 wt%) because it is industrially available. Also,
As the anolyte solution, the catholyte solution, and an aqueous solution of an electrolyte to be a concentrated solution, a 0.1 to 2 (mol / L) sodium hydroxide solution is generally used.

During electrodialysis, water glass or a concentrated liquid may be continuously or intermittently supplied, and desalted water glass or a concentrated liquid having an increased concentration may be continuously or intermittently withdrawn. At this time, in order to prevent an increase in the electric resistance of each ion exchange membrane, it is preferable to perform electrodialysis while stirring the solution in each chamber. As a means for stirring, it is preferable to circulate each liquid, and for that purpose, a storage tank is provided outside each chamber for each type of liquid, and a pump or the like is used between each chamber and the external storage tank. It is preferable to circulate the liquid. By adopting such a method, it becomes easy to control the desalted state of the dealkalized water glass of the product.

The current density during electrodialysis is not particularly limited, but generally exceeds 0 A / dm ² and 10 A / dm ^2.
dm ² or less, it is preferable 5A / dm ² or less, especially beyond the 0A / dm ^2. Usually, when electrodialysis is carried out by such a method and desalination of water glass is carried out for a long time, precipitates mainly composed of silicate are gradually generated in the desalting chamber and the concentrating chamber. Supply becomes difficult, and it becomes difficult to continue desalination.

In the production method of the present invention, electrodialysis is carried out while removing the above-mentioned precipitates causing such a phenomenon by any solid-liquid separation means. In the present invention, the method for removing the precipitate is not particularly limited, but generally, a known filter such as a cartridge filter or a bag filter can be used to remove the precipitate existing in the water glass. Further, the pore size of the filter used for removing the precipitate is preferably as small as possible so as not to adversely affect the lifting of the liquid supply pump and the pressure resistance of the piping and the like. Therefore, the pore size of the filter in the present invention is 1 μm to 100 μm, and particularly 1 μm to 20.
It is preferable to use a micrometer type.

[0026]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Example 1 The raw water glass was desalted using the apparatus shown in FIG. Tokuyama electrodialyzer (TS with specifications shown in Table 1
2-10 type), JIS No. 3 water glass is diluted with water to obtain a SiO ₂ content of 4.6 wt% (Na ₂ O concentration of 1.4).
Water glass adjusted to 5 wt%) is supplied to the desalting chamber, and sodium hydroxide aqueous solution adjusted to 0.5 (mol / L) by diluting sodium hydroxide with water is supplied to the concentration chamber to perform desalting treatment. Was done. At this time, a cartridge filter having a pore diameter of 10 μm was installed in the water glass supply passage and the concentrated liquid supply passage. In the first electrodialysis by the above apparatus using a new ion exchange membrane, the average current density when treated until the Na ₂ O concentration of ₂ L of water glass as the raw material solution becomes 0.49 wt% is 1.4 (A / Dm ² ) and the time required for dealkalization was 52 minutes. Table 2 shows the liquid composition and electrodialysis performance before and after electrodialysis.

After the above-mentioned first electrodialysis, the same operation was repeated, and after a total of 300 hours of energization, 2 L of water glass was used as the water glass for 52 minutes to measure the electrodialysis performance. . Table 3 shows the liquid composition and electrodialysis performance before and after electrodialysis. The average current density at this time was 1.4 (A / dm ² ), confirming that the electrodialysis performance did not deteriorate. After completion of dialysis, the electrodialysis tank was disassembled and the inside was observed, but no precipitate was observed.

[Table 1]

[Table 2]

[Table 3]

Example 2 Raw water glass was desalted using the apparatus shown in FIG. Tokuyama electrodialyzer (TS with specifications shown in Table 1
2-10 type), JIS No. 3 water glass is diluted with water to obtain a SiO ₂ content of 4.6 wt% (Na ₂ O concentration of 1.4).
Water glass adjusted to 5 wt%) is supplied to the desalting chamber, and sodium hydroxide aqueous solution adjusted to 0.5 (mol / L) by diluting sodium hydroxide with water is supplied to the concentration chamber to perform desalting treatment. Was done. At this time, a cartridge filter having a pore diameter of 100 μm was installed in the water glass supply passage and the concentrated liquid supply passage. In the first electrodialysis with the above equipment using a new ion exchange membrane, ₂ L of water glass Na ₂ O
The average current density when treated until the concentration reached 0.49 wt% was 1.4 (A / dm ² ), and the time required for dealkalization was 52 minutes. Table 2 shows the liquid composition and electrodialysis performance before and after electrodialysis.

After the above-mentioned first electrodialysis, the same operation was repeated, energizing for a total of 250 hours, and then energizing for 70 minutes using 2 L of water glass aqueous solution as water glass to measure the electrodialysis performance. did. Table 4 shows the liquid composition and electrodialysis performance before and after electrodialysis. The average current density at this time was 1.0 (A / dm ² ), and it was confirmed that the electrodialysis performance was lowered. After the completion of dialysis, the electrodialysis tank was disassembled and the inside was observed. As a result, precipitates were found in some of the desalting chambers.

[Table 4]

Comparative Example 1 Water glass was electrodialyzed in the same manner as in Example 1 except that no filters were installed in the water glass supply passage and the concentrate supply passage. In the first electrodialysis, ₂ L of water glass, which is water glass, has a Na ₂ O concentration of 0.49 wt%
Average current density is 1.4 (A /
dm ² ) and the time required for dealkalization was 52 minutes. Liquid composition and electrodialysis performance before and after electrodialysis are shown in Table 2.
Shown in. After the first electrodialysis, the same operation was repeated, and after energizing for a total of 250 hours, 2 L of water glass was used as water glass for 104 minutes to measure electrodialysis performance. Table 5 shows the liquid composition before and after electrodialysis and the electrodialysis performance. The average current density at this time was 0.7 (A / dm ² ), and it was confirmed that the electrodialysis performance was lowered. After the completion of dialysis, the electrodialysis tank was disassembled and the inside was observed. As a result, precipitates were found in some of the desalting chambers.

[Table 5]

[0031]

According to the production method of the present invention, water glass is dealkalized by an ion exchange membrane electrodialysis method, and it is preferable to use water glass with a high molar ratio as a ground improvement material and for building materials and adhesives. Effectively suppresses the formation of silicate-based precipitates in the desalting chamber (and the concentrating chamber) during electrodialysis during the production of dealkalized water glass that can be used as a raw material for silica production. can do. For this reason, it becomes possible to stably and continuously perform electrodialysis.

[Brief description of drawings]

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

[Explanation of symbols] 1 ... Electrodialysis device 2 ... Anode 3 ... Cathode 4 ... Anion exchange membrane 5 ... Cation exchange membrane 6 ... Anode chamber 7 ... Cathode chamber 8 ... Desalination chamber 9: Concentration room 10. Water glass supply channel 11. Concentrated liquid supply path 12 ... 13 ... Concentrated liquid withdrawal path 14 ... Anolyte supply path 15 ... Cathode supply path 16 ... Anode discharge path 17 ... Cathode drainage path 18. Water glass storage tank 19 ... Concentrated liquid storage tank 20 ... Water glass filter 21 .. Concentrated liquid filter

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) E02D 3/12 101 C09K 103: 00 // C09K 103: 00 B01D 35/02 A (72) Inventor Ryuji Takeshita 1-1 Mikagecho, Tokuyama City, Yamaguchi Prefecture, Tokuyama Co., Ltd. (72) Inventor, Kyoji Miyahara 2-4, 9-2, Mindan, Chiyoda-ku, Tokyo Toso Sangyo Co., Ltd. (72) Tetsuji Kintaka 2-4, 9-2 Minamidandan, Chiyoda-ku, Tokyo F-term in Toso Sangyo Co., Ltd. (reference) 2D040 AA04 AA06 CB03 4D006 GA17 HA47 JA41A JA42A JA43A JA44A KA02 KB14 MA13 MA14 MB12 PB70 PC80 4D064 BA21 4G072 AA50 GG03 MM03 MM04 HH21 PP13 UU07 4H026 CA03 CC04 CC06

Claims (2)

[Claims] 1. A desalination in which 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 partitioned by the anion exchange membrane and the cation exchange membrane, respectively. Chamber, and an electrodialysis device in which the anode side and the cathode side were alternately formed with a concentration chamber partitioned by a cation exchange membrane and an anion exchange membrane, respectively, and water glass was circulated and supplied to the desalting chamber for electrodialysis. A method for producing a dealkalized water glass, comprising removing deposits present in the water glass to be circulated and supplied. 2. (a) A cation exchange membrane and an anion exchange membrane are alternately arranged between the anode and the cathode, and the anode side and the cathode side are partitioned by the anion exchange membrane and the cation exchange membrane, respectively. To store a desalting chamber, and an electrodialysis tank having a concentrating chamber whose anode side and cathode side are partitioned by a cation exchange membrane and an anion exchange membrane, respectively, and (b) to store water glass supplied to the desalting chamber. Water glass storage tank, a water glass supply passage for supplying water glass from the water glass storage tank to the desalination chamber, and a desalination water glass return passage for returning water glass desalted in the desalination chamber to the water glass storage tank. An apparatus for producing dealkalized water glass, comprising: a formed water glass circulation path, wherein a deposit removing means is installed in the water glass circulation path.