JP2007070133A - Method for producing particulate silica slurry for cement composition, and particulate silica slurry for the cement composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method capable of obtaining particulate silica slurry for a cement composition free from the precipitation and flocculation of particles in the slurry and having excellent performance, and to provide particulate silica slurry for a cement composition having improved fluidity and strength developability compared with the case where it is jointly used with cement, the case where silica fumes are used in the form of powder and the case where it is only dispersed into water. <P>SOLUTION: Regarding the method for producing particulate silica slurry for a cement composition, raw material silica slurry comprising silica fumes is subjected to wet pulverizing using a pulverizing medium such as a medium stirring type wet pulverizer. In the method, the revolving speed of a rotor in the medium stirring type wet pulverizer is ≥400 RPM and/or the circumferential speed of the medium stirring type wet pulverizer is ≥3 m/s. The silica fumes are composed of amorphous silica comprising ≥80% SiO<SB>2</SB>, and/or are composed of amorphous silica in which the maximum particle diameter of non-primary particles is ≤1 μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is used, for example, as a cement composition, an admixture used for cement paste, mortar and concrete, a filler for filling a crack in a concrete structure or rock, and an injection used for ground improvement. The present invention relates to a method for producing a silica fume-containing fine-particle silica slurry for cement composition containing amorphous silica as a main component and the fine-particle silica slurry for cement composition.

  Conventionally, fine powders mainly composed of amorphous silica such as silica fume have been used mainly as powders and as admixtures for cement compositions, but there are some problems because the powders are ultra fine powders. .

  For example, it may be difficult to handle such as transportation and weighing due to its large bulk specific gravity on the work surface, and it may be difficult to mix uniformly when mixing with materials such as cement on the use surface. It was sometimes difficult to handle.

  As means for solving these problems, there are a method in which powder is granulated in advance (see Patent Document 1), a method in which a dispersant is used in combination with a slurry, and a method in which powder is dispersed in water in advance and used as a slurry. Proposed (see Patent Document 2, Patent Document 3 and Patent Document 4), and a method for reducing the viscosity of the slurry has also been proposed (see Patent Document 5).

  Silica fume, on the other hand, is an ultra-fine powder, but in fact, it is agglomerated due to adhesion between primary particles during production as well as granulated products, and then agglomeration of primary particles due to static electricity and moisture. Accordingly, some of the particles are actually secondary particles of several μm to several hundred μm (see Non-Patent Document 1 and Non-Patent Document 2).

  When silica fume is mixed with water or water combined with a dispersant to form a slurry, some of the particles are dispersed in the form of primary particles, but the particles with strong aggregation remain secondary particles without being dispersed into the primary particles. In addition, depending on the state of the slurry, such as the concentration, pH, and type of dispersant, primary particles once dispersed may become secondary particles in the slurry.

As a solution to this problem, a method of dispersing the slurry by applying a shearing force has been proposed (see Patent Document 6), but there is no specific description of the particle size of the slurry after treatment, and the pulverization effect is not satisfactory. It is clear.
Further, such a pulverizer can disperse to secondary particles of about several microns, but it is said that it is difficult to process the particles to 2 μm or less almost completely.
Therefore, when a silica fume slurry is produced by such a method, in the long term, secondary particles having a large particle size settle in the slurry, and the stability of the slurry as well as the use of the precipitated particles may cause trouble in use. There are concerns.

JP 2001-253741 A JP 61-117143 A JP-A-62-180741 Japanese Patent Laid-Open No. 02-145417 JP 07-257950 A Japanese Patent Laid-Open No. 01-141006 Latest technology and application of concrete admixture, P210 ~ 212, CMC Publishing Guidelines for the design and construction of concrete using silica fume (draft), P63-66, Japan Society of Civil Engineers

  The present invention is, for example, a cement composition, an admixture used for cement paste, mortar, and concrete, a filler for filling a crack in a concrete structure or rock, and an injection material used for ground improvement. As a result of intensive investigations on the silica fume used, it has been found out that a fine silica slurry for cement composition with excellent performance without sedimentation or aggregation of particles in the slurry can be provided by specific wet grinding. .

The present invention is a method for producing a fine particle silica slurry for cement composition obtained by wet pulverizing a raw silica slurry containing silica fume using a pulverizing medium, which is also wet pulverized by a medium stirring wet pulverizer. A method for producing a fine particle silica slurry for a cement composition, wherein the rotational speed of a rotor of a medium stirring wet pulverizer is 400 RPM or higher and / or a peripheral speed of the medium stirring wet pulverizer is 3 m / S or higher. A method for producing a fine particle silica slurry for a composition, wherein the average particle size of a grinding medium is 2 mm or less, and a method for producing a fine particle silica slurry for a cement composition, wherein the silica fume contains 80% or more of SiO _2. In the method for producing a fine particle silica slurry for a cement composition, which is amorphous silica and / or amorphous silica whose non-primary particles have a maximum particle size of 1 μm or less. The fine particle silica slurry for cement composition produced by the method for producing fine particle silica slurry for cement composition, wherein 80% or more of silica fume is 1.0 μm or less, and the maximum particle size of silica fume is 2.0 μm or less. The fine particle silica slurry for cement composition, the fine particle silica slurry for cement composition having a silica fume of 20 to 65%, and the fine particle silica slurry for cement composition having a pH of 3 to 9.

By the production method of the present invention, a fine particle silica slurry for a cement composition having excellent performance without sedimentation or aggregation of particles in the slurry can be obtained.
The obtained fine particle silica slurry for cement composition is a fine particle silica slurry having a specific particle size or less. When used in combination with cement, the silica fine particle is used in a flow as compared with the case where silica fume is used in powder form or simply dispersed in water. And strength development are improved.
Moreover, when using as an injection material, the outstanding permeability is obtained.

  Unless otherwise specified, parts and% in the present invention are shown on a mass basis.

Silica fume (hereinafter referred to as SF) used in the present invention is a by-product generated from an electric furnace in the process of producing metallic silicon, ferrosilicon, or zirconia, and is an ultrafine powder mainly composed of amorphous silica. If it is, it will not specifically limit.
The composition of SF is preferably 80% or more, more preferably 85% or more of the SiO ₂ component in all components. If the SiO ₂ component is less than 80%, the cohesiveness becomes strong and slurrying may be difficult.
Further, the maximum particle size of SF is preferably 1.0 μm or less, and more preferably 0.8 μm or less. If it exceeds 1.0 μm, the quality may not be stable, and improvement in fluidity and strength may not be obtained.
Since SF is usually a granulated product as well as a powdered product, some of the particles are secondary particles of several μm to several hundred μm due to agglomeration. .

  In the present invention, SF is dispersed in a solvent to obtain a raw material silica slurry, and wet pulverized using a pulverizing medium to prepare a fine particle silica slurry for cement composition (hereinafter referred to as a fine particle slurry) containing SF.

The solvent in which the SF is dispersed is usually water, but can be replaced with alcohol such as ethanol up to several percent.
The amount of the solvent used is preferably about 55 to 400 parts with respect to 100 parts of SF.

  In the fine particle slurry of the present invention, fine particles can be obtained by pulverization with water alone. However, when the concentration is high, in order to improve the pumpability of the raw silica slurry, the stability of the fine particle slurry is maintained after pulverization. Therefore, it is preferable to use a pH adjuster or dispersant that lowers the viscosity.

Examples of pH adjusters include inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid, citric acid, malic acid, tartaric acid, and organic acids such as gluconic acid or sodium salts and potassium salts thereof. Organic acids are preferred.
The amount of the pH adjuster used is preferably 2.0 parts or less and more preferably 1.0 part or less with respect to 100 parts of SF.

As the dispersant, any dispersant such as lignin sulfonate, oxycarboxylate, naphthalene sulfonate formalin condensate, polycarboxylate, aromatic amino sulfonate, and cellulose derivative can be used. is there.
The amount of the dispersant used is preferably 0.3 to 2.0 parts with respect to 100 parts of SF.

  As the wet pulverizing apparatus used in the present invention, a medium stirring pulverizer is preferable.

The medium agitation type pulverizer is a pulverizer in which a pulverization medium such as a ball is placed in a container, and the pulverization is performed by transmitting force to the pulverization medium by an agitation mechanism (hereinafter referred to as a rotor) installed in the container. And classified into a stirring tank type pulverizer, a flow tube type pulverizer, an annular pulverizer, a tower type pulverizer, and the like.
Among the stirring pulverizers, there are a product name “Attritor” manufactured by Mitsui Mining Co., Ltd. and a product name “Sand Grinder” manufactured by Imex Co., Ltd.・ Product name “Dyno mill” manufactured by Bakkofen AG, product name “Ultra Visco Mill” manufactured by IMEX, product name “Super Apex Mill” manufactured by Kotobuki Giken Kogyo Co., Ltd., product name “OB Mill” manufactured by Turbo Kogyo Co., Ltd. There are the product name “SC Mill” and the product name “Star Mill” manufactured by Ashizawa Finetech Co., Ltd. As the circular crusher, the product name “Diamond Fine Mill” manufactured by Mitsubishi Heavy Industries, Ltd. Pearl mill "etc.
Of these, a circulation pipe type crusher having excellent crushing performance is preferable.

In the stirring pulverizer, the pulverization medium to be used is not particularly limited, but the average particle size is preferably 2 mm or less, more preferably 0.01 to 2.0 mm, and most preferably 0.05 to 1.0 mm. If it exceeds 2.0 mm, pulverization may be difficult due to difficulty in pulverization.
The filling amount of the grinding medium in the container is not particularly limited, but is preferably 50 to 95% by volume, more preferably 70 to 90% by volume of the volume of the container. Outside this range, the pulverization efficiency may decrease.
The material of the grinding medium is not particularly limited, and alumina ceramics such as alumina, zirconia, silicon nitride, and silicon carbide are usually used.

  The ability of the rotor for stirring the pulverization medium of the stirring pulverizer to be used varies depending on the type, but the rotational speed is preferably 400 RPM or more, more preferably 400 to 4,500 RPM, and most preferably 1,500 to 3,500 RPM. If it is less than 400 RPM, the crushing effect may not be obtained.

  The circumferential speed of the rotor is preferably 3 to 35 m / S, more preferably 10 to 30 m / S. If it is less than 3 m / S, the pulverizing effect may be reduced, and SF particles of 2 μm or more may remain.

  In the present invention, 80% or more of the particle size of SF in the fine particle slurry is preferably 1.0 μm or less, and the maximum particle size is preferably 2.0 μm or less.

  80% or more of the particle size of SF in the fine particle slurry is preferably 1.0 μm or less. When the number of particles exceeding 1.0 μm increases, sedimentation occurs, and it may be difficult to stabilize the fine particle slurry.

  Further, the maximum particle size of SF in the fine particle slurry is preferably 2.0 μm or less. If it exceeds 2.0 μm, it may be difficult to stabilize the fine particle slurry.

  The concentration of SF in the raw material silica slurry is preferably 20 to 65%, more preferably 30 to 50%. If it is less than 20%, the amount of water increases, resulting in a decrease in production efficiency, cost, and economical in terms of transportation. If it exceeds 65%, the viscosity of the slurry increases and the particles become finer during grinding. In addition to the deterioration of the efficiency, clogging troubles may occur when the raw silica slurry is pumped or crushed.

  The pH of the fine particle slurry is preferably 3-9. If the pH is less than 3, there is a risk of corroding equipment that is strongly acidic, and if the pH exceeds 9, the particles may aggregate and the viscosity of the slurry may increase or gel.

  Hereinafter, although an example and a comparative example are given and the contents are explained in detail, the present invention is not limited to these.

Experimental example 1
An equal amount of SF and water was mixed, and sulfuric acid was used in combination to adjust the pH to 5 to 6, followed by stirring with a hand mixer for 5 minutes to prepare a raw material silica slurry. The particle size distribution of SF in the raw silica slurry is shown in FIG.
Using the hose pump, the prepared raw material silica slurry is transported to a medium stirring wet pulverizer, a product name `` Super Apex Mill '' manufactured by Kotobuki Kogyo Co., Ltd. 80% of the container of the medium stirring type wet pulverizer was filled, and wet pulverization was performed at the number of rotations of the rotor shown in Table 1 to prepare a fine particle silica slurry. The concentration of SF in the fine particle slurry was 50%. The particle size distribution of SF in the fine particle slurry is shown in FIG.
The viscosity and pH of the fine particle silica slurry immediately after production, the particle size of 1 μm or less, the ratio of the particle size exceeding 1 μm on the particle size of 1 μm, and the particle size distribution of the maximum particle size were measured. The results are also shown in Table 1.

<Materials used>
SF: Commercially available product, SiO ₂ 93%, non-primary particles of amorphous silica with a maximum diameter of 0.8 μm, density 2.29 g / cm ³ , BET specific surface area 19 m ² / g, average particle size 67.0 μm
Water: Tap water

<Measurement method>
Viscosity: Measure fine particle slurry with B-type rotational viscometer at 20 ° C. and rotor speed 20 RPM. PH: Measure fine particle slurry with pH meter D-51 manufactured by HORIBA. Particle size distribution: Laser diffraction manufactured by HORIBA. / Measured using a scattering type particle size distribution measuring instrument trade name “LA-910W”. As a pretreatment for measurement, ultrasonic dispersion is not used.

Experimental example 2
The test was performed in the same manner as in Experimental Example 1 except that wet pulverization was performed at the peripheral speed of the rotor shown in Table 2. The results are also shown in Table 2.

Experimental example 3
The test was carried out in the same manner as in Experimental Example 1 except that the rotation speed of the rotor was 2,000 RPM, the peripheral speed of the rotor was 16.7 m / S, and the zirconia grinding media shown in Table 3 were used. The results are also shown in Table 3.

Experimental Example 4
The experiment was performed in the same manner as in Experimental Example 1 except that the rotor rotation speed was 2,000 RPM, the rotor peripheral speed was 16.7 m / S, and the raw material silica slurry having the SF concentration shown in Table 4 was used. The results are also shown in Table 4.

Experimental Example 5
The test was performed in the same manner as in Experimental Example 1 except that the rotation speed of the rotor was 2,000 RPM, the peripheral speed of the rotor was 16.7 m / S, the pH of the raw silica slurry was as shown in Table 5, and the viscosity and pH were measured. The results are also shown in Table 5.

Experimental Example 6
Fine particles as in Experimental Example 1 except that the rotor speed was 2,000 RPM, the rotor peripheral speed was 16.7 m / S, the pH of the raw silica slurry was 8, and the SF concentration in the raw silica slurry was 50%. A slurry was prepared. The pH of the fine particle slurry was:
50% fine particle slurry 200 kg, cement 1,000 kg, fine aggregate 1,250 kg, high strength admixture 20 kg, high-performance AE water reducing agent 16.8 kg, and water and water reducing agent in the fine particle slurry A mortar was prepared with an amount of water of 230 kg, a water binder ratio of 20.5%, which is the ratio of water and cement, a high-strength admixture, and SF. The flow and compressive strength were measured. The results are also shown in Table 6.

<Materials used>
Cement: Ordinary Portland cement fine aggregate: Ferronickel slag fine aggregate high-strength admixture: Anhydrous gypsum-based commercial product High-performance AE water reducing agent: Polycarboxylic acid-based, commercial product

<Measurement method>
Flow: Conforms to JIS R 5201 Compressive strength: Conforms to JIS R 5201, measured at 28 days of age

  According to the present invention, it is widely used in civil engineering fields such as admixtures used for cement paste, grout, mortar and concrete, and fillers for filling concrete structures and rock cracks or injecting materials used for ground improvement. Applicable.

FIG. 1 shows the particle size distribution measurement result of SF in the raw silica slurry. FIG. 2 shows the measurement result of the particle size distribution of SF in the fine particle slurry.

Claims (11)

  A method for producing a fine particle silica slurry for a cement composition obtained by wet-grinding a raw material silica slurry containing silica fume using a grinding medium.   The manufacturing method of the fine-particle silica slurry for cement compositions of Claim 1 which wet-grinds the raw material silica slurry containing a silica fume with a medium stirring wet pulverizer.   The method for producing a fine particle silica slurry for a cement composition according to claim 2, wherein the rotation speed of the rotor of the medium stirring wet pulverizer is 400 RPM or more.   The method for producing a fine particle silica slurry for a cement composition according to claim 2 or 3, wherein the peripheral speed of the rotor of the medium stirring wet pulverizer is 3 m / S or more.   The method for producing a fine particle silica slurry for a cement composition according to any one of claims 1 to 4, wherein an average particle diameter of the grinding medium is 2 mm or less. Silica fume, the production method of the particulate silica slurry cement composition according to any one of claims 1 to claim 5 is an amorphous silica comprising the SiO ₂ more than 80%.   The method for producing a fine particle silica slurry for a cement composition according to any one of claims 1 to 6, wherein the silica fume is amorphous silica whose non-primary particles have a maximum particle size of 1 µm or less.   The fine particle silica slurry for cement compositions manufactured by the manufacturing method of the fine particle silica slurry for cement compositions as described in any one of Claims 1-7.   The fine particle silica slurry for cement composition according to claim 8, wherein 80% or more of the silica fume is 1.0 µm or less and the maximum particle size of the silica fume is 2.0 µm or less.   The fine-particle silica slurry for cement composition according to claim 8 or 9, wherein the silica fume is 20 to 65%.   The fine particle silica slurry for cement composition according to any one of claims 8 to 10, which has a pH of 3 to 9.

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