JP6102404B2 - Method and equipment for producing silica sol grout - Google Patents

Description

  The present invention relates to a method and equipment for producing silica sol grout that can be used for ground improvement and the like.

  As an injection material (chemical solution) used in the chemical solution injection method, there is a water glass grout that is made to gel by adding a reactive agent such as an acid. However, when this water glass grout is used, the water glass is highly alkaline, so that the ground becomes alkaline with a pH of about 10 to 12, and the ground water on the ground may become alkaline. Moreover, when water glass type grout is used, since water glass which did not gelatinize will elute from the ground, there exists a possibility that durability of an injection | pouring ground may become inadequate.

  Therefore, at present, there is a method (construction method) in which water glass and an acid as a neutralizing agent are mixed to obtain a non-alkaline or acidic silica sol grout, and this silica sol grout is used as an injection material. Although this method uses water glass as a raw material, the silica particles are processed into a sol and then injected into the ground. Therefore, the problem as in the case of using the water glass grout does not occur.

  Further, this silica sol grout has been further improved. For example, an injection material in which polyaluminum chloride (PAC) is added to non-alkaline or acidic silica sol has been proposed (for example, Patent Documents 1 and 2). Etc.). This injection material can adjust the gel time freely, and is said to be very useful. However, although this injection material can freely adjust the gel time, the production process (liquid production process) has the following problems as in the case of silica sol grout before improvement.

  That is, as a method for producing silica sol grout, for example, as shown in (1) of FIG. 3, there is a method of adding diluted water glass Y to diluted acid X while stirring diluted acid X with stirring means 101. . However, this manufacturing method has a problem that when the mixing ratio of the water glass Y to the diluted acid X is increased, stirring by the stirring means 101 becomes difficult. Further, according to this production method, when water glass Y is mixed into diluted acid X, the pH becomes unstable (pH shock), and a partial gel may be generated.

  On the other hand, as a method for producing silica sol grout, for example, as shown in (2) of FIG. 3, there is a method of mixing diluted acid X and diluted water glass Y using a line mixer 102. However, in this manufacturing method, gelation occurs when the mixing ratio of the diluted water glass Y to the diluted acid X is increased. Therefore, the mixing ratio of the diluted water glass Y cannot be increased, and the silica concentration of the obtained silica sol grout cannot be sufficiently increased. In this regard, in recent years, there is a strong demand for improving the strength of the injected ground, and an improvement in the silica concentration is also strongly desired. Therefore, the manufacturing method in which the silica concentration cannot be made sufficiently high has a great weak point. Also in this production method, the pH becomes unstable when the diluted acid X and the diluted water glass Y come into contact with each other in the line mixer 102, and thus a partial gel may be generated.

JP 59-196388 JP 2012-241368 A

  The main problem to be solved by the present invention is to provide a method and equipment for producing silica sol grout that can increase the silica concentration.

The present invention for solving this problem is as follows.
[Invention of Claim 1]
A method for producing a silica sol grout having a silica concentration of 12 to 20 (mass / volume) by mixing water glass and an acid,
Has a storage tank and a line mixer, using a liquid circulation mechanism Kaeeki passage facilities leading to liquid feed path and the other end connected to one end of the line mixer, the acid of the liquid storage tank, the feed Send to the line mixer through the liquid path, after passing through this line mixer, circulate by returning to the liquid reservoir through the liquid return path ,
By sending water glass to the line mixer through a water glass supply path connected to one end of the line mixer, the water glass is mixed in the circulating acid in the line mixer .
A method for producing a silica sol grout characterized by the above.

[Invention of Claim 2]
The flow rate of the water glass to be mixed in the line mixer, a 1 / 0.5 / 10 of the flow rate of the liquid to be sent to the line mixer through the liquid feed path,
The method for producing a silica sol grout according to claim 1.

[Invention of Claim 3]
At the stage where the silica concentration in the liquid storage tank has increased to a predetermined value, the liquid in the liquid storage tank starts to be extracted while the acid is circulated. Add
A method for producing a silica sol grout according to claim 1 or 2.

[Invention of Claim 4]
The addition of the acid is performed on the liquid feeding path .
The method for producing a silica sol grout according to claim 3.

[Invention of Claim 5]
Withdrawing the liquid from the return path ,
A method for producing a silica sol grout according to claim 3 or claim 4.

[Invention of Claim 6]
A facility for producing silica sol grout having a silica concentration of 12 to 20 (mass / volume) by mixing water glass and acid,
It has a storage tank and a line mixer, wherein Ri Kaeeki path leading to the liquid feed path and the other end connected to one end of the line mixer Sonawa, the acid of the liquid storage tank, said through said liquid feed path A liquid circulation mechanism that is sent to a line mixer and then circulated by returning to the liquid storage tank through the liquid return path after passing through the line mixer ;
An acid supply means for supplying an acid to the liquid storage tank , and a water glass supply path connected to one end of the line mixer and supplying water glass to the line mixer , the water glass supply path When the water glass is sent to the line mixer through, the water glass is mixed into the circulating acid in the line mixer .
A production facility for silica sol grout characterized by the above.

  According to the present invention, a silica sol grout production method and production equipment capable of increasing the silica concentration are provided.

It is a manufacturing equipment flow figure of silica sol grout concerning this form. It is a modification of the manufacturing equipment flowchart of the silica sol grout which concerns on this form. It is a manufacturing equipment flow diagram of the conventional silica sol grout.

Next, an embodiment of the present invention will be described.
The silica sol grout production facility of this embodiment is a facility for producing non-alkaline or acidic silica sol grout by mixing water glass and acid, and circulating acid (liquid) or liquid obtained by mixing water glass with this acid. It has a liquid circulation mechanism.

  As shown in FIG. 1, this liquid circulation mechanism has a liquid storage tank 11 and a liquid mixing means, in the illustrated example, a line mixer 2, and a liquid feeding means for sending the liquid in the liquid storage tank 11 to the line mixer 2. In the illustrated example, a liquid return path 21 and liquid return means for returning the liquid from the line mixer 2 into the liquid storage tank 11 are provided, and in the illustrated example, a liquid return path 1 is provided.

  In addition, the manufacturing equipment is provided with water glass supply means for supplying water glass Y to the line mixer 2. This water glass supply means has a water glass storage tank 12 and a water glass supply path 22, and the water glass Y in the water glass storage tank 12 is sent to the line mixer 2 through the water glass supply path 22. .

  In producing the silica sol grout using this production facility, if necessary, the acid X is supplied to the liquid storage tank 11 using an acid supply means (not shown) and the acid X is stored in the liquid storage tank 11. Keep it. The acid X is sent to the line mixer 2 through the liquid feeding path 21, passed through the line mixer 2, and then circulated by returning it to the liquid storage tank 11 through the liquid returning path 1. This circulation can be performed using a circulation pump (not shown).

  The water glass Y is mixed in the circulating acid X in the line mixer 2. The mixing of the water glass Y is performed through the water glass supply path 22. According to such a mixing method of the acid X and the water glass Y, since the water glass Y is gradually mixed with the circulating acid X, there is little pH shock. Therefore, the final mixing ratio of the water glass Y can be increased, and the silica concentration of the obtained silica sol grout can be sufficiently increased.

  The flow rate of the water glass Y mixed in the line mixer 2 is preferably 1 / 0.5 to 1/10 of the flow rate of the liquid sent to the line mixer 2 through the liquid feed path 21, and 1/1 to 1 / 10 is more preferable, and 1/3 to 1/10 is particularly preferable. If the mixing ratio of water glass Y exceeds 1 / 0.5, a partial gel may be generated, and this partial gel may cause clogging of the liquid return path 1 in particular. On the other hand, when the mixing ratio of the water glass Y is too low, there is no possibility that a partial gel is produced, but the working efficiency is deteriorated. Further, since the silica sol in the solution having a high acid concentration is unstable, the gelation time is shortened and there is no possibility that a partial gel is formed, but the entire solution may be gelled.

  In addition, although the liquid sent to the line mixer 2 through the liquid sending path 21 is initially the acid X, the liquid circulated by mixing of the water glass Y in this step is a mixed solution (reaction of the acid X and the water glass Y). Therefore, it becomes a mixed solution from the middle.

  Various improvements can be added to the above manufacturing equipment. Accordingly, for example, as shown in FIG. 2, when the silica concentration of the liquid in the liquid storage tank 11 has increased to a predetermined value, the liquid (the mixed liquid) in the liquid storage tank 11 is extracted through the drainage passage 23. It is preferable to start. The extracted liquid has a silica concentration increased to a predetermined value, and can be used as it is or after appropriately performing necessary treatment as a silica sol grout as an injection material.

  Here, the “predetermined value” of the silica concentration is a desired silica concentration of the obtained silica sol grout and can be, for example, 12 to 20 (mass / volume)%. If the predetermined value (silica concentration) exceeds 20%, partial gel may be generated in the liquid return path 1. On the other hand, when the predetermined value is less than 12%, the superiority of the present method over the conventional method becomes insufficient.

  On the other hand, when the liquid in the liquid storage tank 11 is withdrawn as described above, the acid X necessary for producing a silica sol grout of the same amount as that of the liquid to be withdrawn, that is, the volume of the liquid to be withdrawn It is added in the liquid storage tank 11. By adding this acid X, it is possible to continuously produce silica grout.

  The addition of the acid X can be performed using, for example, an acid supply unit having the acid storage tank 13 and the acid supply path 24. When using this acid supply means, the acid X stored in the acid storage tank 13 is supplied into the liquid storage tank 11 through the acid supply path 24. However, the acid X in the acid storage tank 13 can be sent (supplied) to the liquid supply path 21 instead of the liquid storage tank 11. According to this method, the supplied acid X can be prevented from being extracted from the liquid storage tank 11 before being mixed with the water glass Y. In addition, the acid X can be sent to the liquid feeding path 21 through the communication path 25, for example.

  On the other hand, in order to prevent the acid X from being extracted from the liquid storage tank 11 before being mixed with the water glass Y, the liquid (mixed liquid) is passed from the liquid return path 1 through the second drain path 26. ) Can be considered.

[Water glass]
Examples of the water glass include sodium silicate (XNa ₂ O · YSiO ₂ ) equivalent to JIS 1408, that is, JIS No. 1, No. 3, No. 3 water glass, and a high molar ratio of 4 or more by dissolving silicon. One type or two or more types can be selected and used from water glass having a ratio, water glass having a high molar ratio by dealkalization, and the like.

In this embodiment, water glass containing an alkali metal other than sodium, for example, potassium or lithium as a component can also be used. JIS No. 3 water glass is a water glass composed of SiO ₂ (28 to 30% by mass), Na ₂ O (9 to 10% by mass) and water (remainder), and has a molar ratio of 2.8 to 3.33. It is. In addition, when shortening the gel time of a silica sol grout (injection material), it is preferable to use water glass having a molar ratio of 4.5 or more.

  The water glass is preferably diluted with water prior to mixing with the neutralizing acid. If the water glass is diluted with water, gelation of the water glass when mixed with an acid can be more reliably prevented. The dilution with water is preferably performed so that the silica concentration is 25 (mass / volume)% or less, and more preferably 15 to 20 (mass / volume)%.

[Acid as neutralizer]
Since the acid dissociation constants of hydrosilicic acid (H ₂ SiO ₂ (OH) ₂ ) are pKa1 = 9.86 and pKa2 = 13.1, the acid dissociation constant of the acid mixed with water glass is 9. It is preferred to use 86 or less acids. Examples of the acid having an acid dissociation constant of 9.86 or less include sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, formic acid, citric acid, and the like. However, sulfuric acid is preferably mixed from the viewpoint of cost, and hydrochloric acid is preferably mixed from the viewpoint of stability.

  The acid as the neutralizing agent is preferably diluted with water prior to mixing with water glass. When the acid is diluted with water, the heat of hydration of the acid when mixed with water glass is reduced, and gelation of the water glass can be more reliably prevented. The dilution with water is preferably performed so that the acid concentration is 20 to 70 (mass)%, and more preferably 30 to 60 (mass)%.

Next, examples of the present invention will be described.
Using the silica sol grout production facility shown in FIG. 1, a test for mixing acid and water glass was conducted. As the acid X stored in the liquid storage tank 11, diluted sulfuric acid obtained by mixing 75% sulfuric acid and water was used. Moreover, as water glass Y stored in the water glass storage tank 12 and supplied to the line mixer 2, No. 5 water glass (SiO ₂ (26 mass%), Na ₂ O (7.2 mass%)), water, Diluted water glass mixed with was used. The test results are shown in Table 1.

  From this test result, if the flow rate of the water glass Y mixed in the line mixer 2 is 1 / 0.5 to 1/10 of the flow rate of the liquid (X, X + Y) sent to the line mixer 2, the silica concentration is high. Even if the acid X and the water glass Y flow rate (linear velocity) is slow, it has been found that partial gels can be more reliably prevented.

  INDUSTRIAL APPLICABILITY The present invention can be applied as a silica sol grout production method and production equipment that can be used for ground improvement and the like.

  DESCRIPTION OF SYMBOLS 1 ... Liquid return path, 2 ... Line mixer, 11 ... Liquid storage tank, 12 ... Water glass storage tank, 13 ... Acid storage tank, 21 ... Liquid feed path, X ... Acid, Y ... Water glass.

Claims (6)

A method for producing a silica sol grout having a silica concentration of 12 to 20 (mass / volume) by mixing water glass and an acid,
Has a storage tank and a line mixer, using a liquid circulation mechanism Kaeeki passage facilities leading to liquid feed path and the other end connected to one end of the line mixer, the acid of the liquid storage tank, the feed Send to the line mixer through the liquid path, after passing through this line mixer, circulate by returning to the liquid reservoir through the liquid return path ,
By sending water glass to the line mixer through a water glass supply path connected to one end of the line mixer, the water glass is mixed in the circulating acid in the line mixer .
A method for producing a silica sol grout characterized by the above. The flow rate of the water glass to be mixed in the line mixer, a 1 / 0.5 / 10 of the flow rate of the liquid to be sent to the line mixer through the liquid feed path,
The method for producing a silica sol grout according to claim 1. At the stage where the silica concentration in the liquid storage tank has increased to a predetermined value, the liquid in the liquid storage tank starts to be extracted while the acid is circulated. Add
A method for producing a silica sol grout according to claim 1 or 2. The addition of the acid is performed on the liquid feeding path .
The method for producing a silica sol grout according to claim 3. Withdrawing the liquid from the return path ,
A method for producing a silica sol grout according to claim 3 or claim 4. A facility for producing silica sol grout having a silica concentration of 12 to 20 (mass / volume) by mixing water glass and acid,
It has a storage tank and a line mixer, wherein Ri Kaeeki path leading to the liquid feed path and the other end connected to one end of the line mixer Sonawa, the acid of the liquid storage tank, said through said liquid feed path A liquid circulation mechanism that is sent to a line mixer and then circulated by returning to the liquid storage tank through the liquid return path after passing through the line mixer ;
An acid supply means for supplying an acid to the liquid storage tank , and a water glass supply path connected to one end of the line mixer and supplying water glass to the line mixer , the water glass supply path When the water glass is sent to the line mixer through, the water glass is mixed into the circulating acid in the line mixer .
A production facility for silica sol grout characterized by the above.

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