JP3089110B2 - Method for producing calcium carbonate fine particle dispersion - Google Patents

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 precipitated calcium carbonate which is fine, has little secondary aggregation, and has good dispersibility.

[0002]

2. Description of the Related Art At present, a carbon dioxide method is widely used as an industrial production method of precipitated calcium carbonate. In the carbon dioxide method, natural limestone is calcined to obtain quicklime (calcium oxide), and the quicklime is reacted with water to obtain lime milk (a suspension of calcium hydroxide in water). This is a method of obtaining calcium carbonate by conducting carbon dioxide gas generated when limestone is calcined and causing it to react. The calcium carbonate produced in this way is
Depending on the size of the primary particles, or in order to further improve the physical properties at the time of compounding, rubber, plastic, paper, paint, etc. by surface-treating various inorganic or organic surface treatment agents on the particle surface It is widely used in large quantities. However, the precipitated calcium carbonate produced by the carbon dioxide method originally has a strong cohesive force between particles,
A large number of primary particles are aggregated to form a large secondary aggregate. Among them, those having a primary particle diameter of 0.2 μm or less have a particularly strong cohesive force, and even if a large amount of energy is used, the initial primary particle diameter is large. It has been considered impossible to eliminate secondary aggregates while maintaining the following.

When precipitated calcium carbonate containing a large number of such secondary aggregates is blended into rubber, plastic, paper, paint, etc., the secondary aggregated particles behave like large primary particles, resulting in poor dispersion and strength. Physical properties such as reduction, gloss reduction, and insufficient viscosity are caused, and various compounding effects that are originally expected for fine primary particles cannot be obtained. Similarly, even if a surface treatment with various inorganic or organic surface treatment agents is performed on the precipitated calcium carbonate containing a large number of such secondary aggregates, only the surface of the secondary aggregate particles is treated, and a sufficient effect is obtained. Does not work.

Until now, various methods for dispersing these primary particle aggregates have been reported.
13. As disclosed in JP-A-60-210521, etc., generally, precipitated calcium carbonate which has been subjected to carbonation is once dehydrated with a filter press or the like to obtain a press cake having a solid content of 60% or more, and then polyacrylic acid. A high-concentration aqueous suspension with a dispersant such as sodium, or after drying and pulverization, is again suspended in water using the above-described dispersant to form a high-concentration aqueous suspension having a solid concentration of 60% or more. After that, a method of strongly pulverizing and breaking by a ball mill, a sand grinder mill or the like is adopted.

[0005] However, in such a method, a large amount of energy is unavoidable due to the necessity of once pressing up or drying and powdering as a method for obtaining a high-concentration aqueous suspension. It is not only economically disadvantageous because a large amount of energy is consumed due to having to go through a dispersion water suspension process before wet pulverization with a Keddy mill, Coreless mixer, etc. Excessive pulverization destruction occurs in the pulverization container due to merely mechanical pulverization. Thus, at the same time as the dispersion of the aggregate of calcium carbonate is performed, the primary particles are also destroyed, and as a result, the surface state is very unstable, and there is a possibility that secondary aggregates may be formed again, and the particle size distribution is broad. Only heterogeneous calcium carbonate is obtained.

[0006] Further, particularly in Japanese Patent Application Laid-Open No. Sho 60-210521, the target calcium carbonate is usually light calcium carbonate, and among precipitated calcium carbonate having an average particle diameter of 1 to 5 µm, those having relatively low cohesive force. However, it is said that it is difficult to obtain desired physical properties unless a large amount of energy is consumed as described above. Furthermore, when a surface treatment agent having a dispersing function such as sodium polyacrylate is used in order to obtain a high-concentration aqueous suspension, various disadvantages occur due to the limited use thereof, and the preferred method Hard to say.

Japanese Patent Application Laid-Open No. 59-69425 discloses a method for producing precipitated calcium carbonate having good dispersibility by adding a small amount of a strontium salt or a barium salt in a carbonation step of adjusting calcium carbonate by a carbon dioxide gas method. A method has been proposed. According to this method, although precipitated calcium carbonate having good dispersibility can be adjusted,
In the calcium carbonate obtained by the method, strontium salts or barium salts added in the carbonation step are mixed, and it is difficult to remove these strontium salts and barium salts by an economically advantageous method. It is expected that inconveniences will occur depending on the intended use.

[0008]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention overcomes the drawbacks of conventional methods for dispersing precipitated calcium carbonate, particularly fine calcium carbonate, and provides an economically advantageous method of dispersing calcium carbonate. It is intended to provide a production method for obtaining calcium.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, in performing wet grinding, a calcium carbonate aqueous suspension before grinding was prepared so as to satisfy specific conditions. Then, the ratio of the alkali substance, which is considered to be the cause of the formation of secondary aggregates, to the solid content of calcium carbonate is reduced, and the surface is inactivated by removing the alkali substance from the surface of the primary particles. The present inventors have found that it is possible to easily obtain fine and well-dispersed precipitated calcium carbonate without adding a third component which can be an impurity in the aqueous calcium carbonate suspension without preventing coagulation, and completed the present invention. Was.

That is, according to the present invention, when wet-milling precipitated calcium carbonate obtained by passing carbon dioxide gas through lime milk, calcium carbonate aqueous solution previously concentrated so as to satisfy the following conditions a, b and c is used. A method for producing a dispersion of fine particles of calcium carbonate, characterized by using a suspension. a. PH (A) at the end of the carbonation reaction satisfies the following equation: Equation 8.0 ≦ A ≦ 10.0 (measured value at 25 ° C.) b. The pH (B) of the aqueous calcium carbonate solution obtained by stirring and / or allowing the aqueous suspension of calcium carbonate obtained by the above a to simultaneously satisfy the following expression: Expression 10.5 ≦ B (25 (Measured value at ° C) Formula BA ≧ 1.0 c. Concentrating the solid content concentration (C%) of the aqueous calcium carbonate suspension obtained in b above to a solid content concentration (D%) that simultaneously satisfies the following formula. Formula 1.2C ≦ D Formula 15 ≦ D ≦ 30

In the present invention, quicklime used for preparing milk of lime is not particularly limited, but the activity of each quicklime is made as uniform as possible in the limestone firing step, and the alkali substance after the carbonation reaction is completed. In order to make the dissolution rate of the limestone from the secondary aggregates uniform, the size of the limestone to be calcined is preferably 10 mm or less. Also, although the activity of quicklime used is not particularly limited,
In order to increase the elution rate of the alkaline substance from the secondary aggregate after completion of the carbonation reaction, it is preferable to use quicklime having an activity of 60 or more. The method for measuring the activity of quicklime in the present invention is as follows. (Measurement method of quick lime activity) (i) 50 l of deionized water at 40 ° C in a 1 liter beaker.
Add 0 ml and add 2-3 drops of phenolphthalein solution while stirring with a stirrer. (Ii) 10 g of quicklime roughly crushed to a diameter of 2 to 5 mm is put into the beaker at a time, and at the same time, time measurement is started with a stopwatch. (Iii) After 1 minute, 4N-HCl is continuously added dropwise so as to keep the solution slightly reddish. (Iv) Record the amount of 4N-HCl dripped every minute, and use the total amount (unit ml) of 4N-HCl dripped until 10 minutes after quick lime is charged as the activity. Further, in order to increase the elution rate of the alkaline substance from the secondary aggregate after the carbonation reaction, the concentration of the chloride ion in the water that hinders the elution is set at 20.
It is preferable that the content be 0 ppm or less.

There is no particular limitation on the method of obtaining precipitated calcium carbonate by passing carbon dioxide gas through the lime milk, and a conventional method such as a method of passing carbon dioxide gas through lime milk, a method of passing carbon dioxide gas through sprayed lime milk, and the like. According to. Regarding the carbonation reaction conditions, any method such as milk lime concentration, milk lime temperature, carbon dioxide gas concentration, and carbon dioxide gas flow rate can be arbitrarily selected to initiate the carbonation reaction, as long as the desired fine calcium carbonate is obtained. PH (A) at the end of the carbonation reaction is 8.0.
It must be not less than 10.0 and not more than 10.0. If the pH at the end of the carbonation reaction is less than 8.0, the surface of the secondary aggregated particles is firmly covered with calcium carbonate to prevent elution of the alkaline substance, while the pH at the end of the carbonation reaction is 10.0. When it exceeds, the concentration of the remaining alkaline substance surrounding the secondary aggregate is high, and the elution of the alkaline substance is prevented. Then, the aqueous suspension of the obtained fine calcium carbonate is stirred and / or allowed to stand, so that the pH (B) of the aqueous suspension is 10.5 or more and the pH value before and after stirring and / or standing. Is adjusted so that the difference B−A becomes 1.0 or more. PH 1 after stirring and / or standing
If it is less than 0.5, or if the difference BA between the pH values before and after stirring and / or standing is less than 1.0, the elution of the alkaline substance is insufficient, so the following operation is performed. However, calcium carbonate having good dispersibility cannot be obtained.

The aqueous calcium carbonate suspension thus obtained is concentrated to adjust the solid content concentration to 1.2 times or more and 15% or more and 30% or less as compared with that before concentration, and then wet pulverized. Should be performed. If the ratio of the solid content concentration before and after concentration is less than 1.2 times, the reduction ratio of the alkaline substance, which is considered to be a cause of forming secondary aggregates, to the calcium carbonate solid content is insufficient, and the solid content concentration after concentration is low. 15%
If it is less than 30%, the pulverization efficiency is low, which is disadvantageous. If the solid content concentration after concentration exceeds 30%, the viscosity rise due to dispersion of fine particles is large, and subsequent operations become difficult. The pH of aqueous calcium carbonate suspension during wet grinding
Does not need to be particularly defined, but is not less than 10.0 and not more than 11.0
The following is most efficient. When the pH of the aqueous suspension is adjusted to the above range, the pH is adjusted by adding a calcium carbonate aqueous suspension obtained by stirring and / or standing before conducting and / or concentrating carbon dioxide gas. Just do it.

The concentrating equipment to be used does not require a large-scale device such as a filter press, and may employ a suction filter such as an oliever filter or a pressure filter such as a rotary filter. As a method, a concentration method by natural sedimentation may be adopted.
The wet pulverization referred to here is to fill a pulverization chamber with a medium such as glass beads or alumina beads, rotate a disk or a rotor, and pulverize the suspension to be pulverized supplied into the pulverization chamber. And grinding using a device called a sand grinder mill or the like. After the wet pulverization is performed, it can be used at the same pH as it is. However, when there is an adverse effect due to alkali or the like at the time of use, such as a PVC paste sol, a silicone one-part sealing agent, etc., the wet pulverization is performed. The pH of the aqueous calcium carbonate suspension is preferably adjusted to 7.5 or less by passing carbon dioxide gas through. The fine precipitated calcium carbonate used for these means a precipitated calcium carbonate having a primary particle diameter of usually 1.0 μm or less, and the fine and secondary aggregates produced by the present invention have extremely few dispersibility. In the case of precipitated calcium carbonate, it is particularly effective to use those having a primary particle size of 0.2 μm or less, more preferably 0.07 μm or less, which are highly cohesive, compared with other methods. . After the wet pulverization, if necessary, it is supplied to the subsequent steps such as dehydration and drying after the surface treatment with an inorganic or organic surface treating agent which is generally performed or without any treatment. It is possible.

As described above, by preparing an aqueous calcium carbonate suspension before performing wet grinding according to the present invention,
There is no need to consume a large amount of energy to obtain a high-concentration aqueous suspension before wet milling, and even in wet milling at a low solids concentration, which has been economically disadvantageous in the prior art, a short time, e.g. With a residence time of less than a minute, and also with a low share, for example the peripheral speed of the disk or rotor 15
m / sec or less can be sufficiently dispersed in one pulverization treatment, and further, there is no re-agglomeration due to activation of the particle surface, breakage of primary particles, A fine particle dispersion having a uniform distribution and good dispersibility can be obtained. In addition, calcium carbonate prepared according to the present invention has a very good dispersibility compared to conventional calcium carbonate powder even when powdered by dehydration and drying,
Even after surface treatment with various surface treatment agents, it is used for various industrial applications such as rubber, plastic, paper, and paint, and exhibits good physical properties.

[0016]

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. Example 1 A limestone of 1 to 5 mm was fired in an electric furnace to obtain an activity of 80.
By hydrating the quicklime with water having a chloride ion concentration of 30 ppm, 100 liters of lime milk having a specific gravity of 1.055 and a temperature of 8 ° C was prepared. A furnace gas having a carbon dioxide gas concentration of 27% by weight (hereinafter abbreviated as carbon dioxide gas) was passed through the lime milk at a flow rate of 20,000 liters / hour to carry out a carbonation reaction. An aqueous suspension of calcium carbonate by weight was obtained. As a result of observation of this calcium carbonate with an electron microscope, the primary particle diameter was 0.1 mm.
It was 05 μm calcium carbonate. Then at 25 ° C 5
Stirring at 25 ° C.
When the pH reached 10.7, it was allowed to stand, and after 5 hours, the supernatant was removed to obtain a calcium carbonate aqueous suspension concentrated to a solid concentration of 20% by weight. Its pH at 25 ° C. was 10.9. The concentrated calcium carbonate aqueous suspension was subjected to a disk peripheral speed of 12 using a wet grinder Dynomill pilot type (manufactured by WAB).
The wet pulverization was performed under the pulverization conditions of m / sec, an apparent filling amount of the media (0.8 mm diameter glass beads) of 80%, and a residence time of 10 minutes. Table 1 shows the particle size distribution measurement results of the calcium carbonate in the aqueous suspension obtained in the present example by a centrifugal sedimentation type particle size distribution analyzer SA-CP3 (manufactured by Shimadzu Corporation). From the measurement results of the particle size distribution, it is confirmed that the calcium carbonate in the aqueous suspension obtained in this example has extremely good dispersibility.

Example 2 A specific gravity of 1.070 and a temperature of 1 were obtained in the same manner as in Example 1.
100 liters of lime milk at 5 ° C. was prepared. Carbon dioxide gas having a carbon dioxide concentration of 21% by weight was passed through the lime milk at a flow rate of 10,000 liters / hour to carry out a carbonation reaction, and a water suspension of calcium carbonate having a pH of 9.8 at 25 ° C. and a solids concentration of 15% by weight was carried out. A suspension was obtained. As a result of observation with an electron microscope, this calcium carbonate was a calcium carbonate having a primary particle size of 0.15 μm. Thereafter, the suspension was allowed to stand at 30 ° C. for 24 hours, and when the pH of the aqueous calcium carbonate suspension at 25 ° C. reached 11.3, 25% by weight using an Oliver filter was used.
To obtain a concentrated aqueous calcium carbonate suspension. Its pH at 25 ° C. was 11.5. The concentrated aqueous calcium carbonate suspension was wet-pulverized in the same manner as in Example 1. Table 1 shows the particle size distribution measurement results of the calcium carbonate in the aqueous suspension obtained in the present example by a centrifugal sedimentation type particle size distribution analyzer SA-CP3 (manufactured by Shimadzu Corporation). From the measurement results of the particle size distribution, it is confirmed that the calcium carbonate in the aqueous suspension obtained in this example has extremely good dispersibility.

Example 3 A carbonation reaction was carried out in the same manner as in Example 1 except that calcined limestone having an activity of 50 was obtained by calcining in an electric furnace using limestone of 12 to 15 mm. pH 9.0
Thus, an aqueous suspension of calcium carbonate having a solid concentration of 12% by weight was obtained. As a result of observation with an electron microscope, this calcium carbonate was a calcium carbonate having a primary particle size of 0.04 μm. After stirring at 35 ° C. for 12 hours, when the pH of the aqueous calcium carbonate suspension at 25 ° C. reached 10.5,
An aqueous calcium carbonate suspension concentrated to 21% by weight was obtained using an Oliver filter. Its pH at 25 ° C. was 10.5. The concentrated calcium carbonate aqueous suspension was treated with a wet grinder Dynomill pilot type (manufactured by WAB) at a peripheral speed of a disk of 15 m / sec, an apparent filling amount of media (glass beads of 0.8 mm diameter) of 80%, and a residence time of 15%. Wet pulverization under pulverization conditions of minutes. Table 1 shows the particle size distribution measurement results of the calcium carbonate in the aqueous suspension obtained in the present example by a centrifugal sedimentation type particle size distribution analyzer SA-CP3 (manufactured by Shimadzu Corporation). From the measurement results of the particle size distribution, it is confirmed that the calcium carbonate in the aqueous suspension obtained in this example has extremely good dispersibility.

Example 4 The aqueous calcium carbonate suspension obtained by the carbonation reaction described in Example 1 was stirred at 25 ° C. for 12 hours to adjust the pH of the aqueous calcium carbonate suspension at 25 ° C. to 11.8. At that point, an aqueous calcium carbonate suspension concentrated to 18% by weight was obtained by using an Oliver filter. 25 ℃
Was 12.1 in pH. By passing carbon dioxide gas through the aqueous calcium carbonate suspension again, a concentrated aqueous calcium carbonate suspension having a pH of 10.3 at 25 ° C. was obtained. The concentrated calcium carbonate aqueous suspension was subjected to a wet crusher Dynomill pilot type (manufactured by WAB) using a disk peripheral speed of 12 m / sec, a media (0.8 mm diameter glass bead) filling amount of 80%, and a residence time of 5%. Wet pulverization under pulverization conditions of minutes. Table 1 shows the particle size distribution measurement results of the calcium carbonate in the aqueous suspension obtained in the present example by a centrifugal sedimentation type particle size distribution analyzer SA-CP3 (manufactured by Shimadzu Corporation). From the measurement results of the particle size distribution, it is confirmed that the calcium carbonate in the aqueous suspension obtained in this example has extremely good dispersibility.

Comparative Example 1 An aqueous calcium carbonate suspension having a primary particle diameter of 0.05 μm and a solid concentration of 12% by weight was prepared in the same manner as in Example 1 except that the pH at the end of the carbonation reaction was changed to 7.2. A liquid was obtained.
It has a pH at 25 ° C. after standing for 5 days of 8.
However, the supernatant was removed to obtain a 20% by weight aqueous calcium carbonate suspension. The concentrated aqueous calcium carbonate suspension was wet-pulverized in the same manner as in Example 1. Table 2 shows the results of measuring the particle size distribution of the calcium carbonate in the aqueous suspension obtained in this comparative example using a centrifugal sedimentation type particle size distribution analyzer SA-CP3 (manufactured by Shimadzu Corporation). From the measurement result of the particle size distribution, it is confirmed that the calcium carbonate in the aqueous suspension obtained in the present comparative example is poor in dispersibility as compared with Example 1.

Comparative Example 2 The aqueous calcium carbonate suspension (12% by weight) having a pH of 10.7 at 25 ° C. obtained in Example 1 was used without concentration, and wet-pulverized in the same manner as in Example 1. . Table 2 shows the results of measuring the particle size distribution of the calcium carbonate in the aqueous suspension obtained in this comparative example using a centrifugal sedimentation type particle size distribution analyzer SA-CP3 (manufactured by Shimadzu Corporation). From the measurement result of the particle size distribution, it is confirmed that the calcium carbonate in the aqueous suspension obtained in the present comparative example is poor in dispersibility as compared with Example 1.

Comparative Example 3 An aqueous calcium carbonate suspension obtained by the same carbonation reaction as in Example 2 was stirred at 25 ° C. for 3 hours, and the pH of the aqueous calcium carbonate suspension at 25 ° C. was 10.5. , A 25% by weight aqueous calcium carbonate suspension was obtained using an Oliver filter. 25 ℃
Was 10.7. The concentrated aqueous calcium carbonate suspension was wet-pulverized in the same manner as in Example 1. Table 2 shows the results of measuring the particle size distribution of the calcium carbonate in the aqueous suspension obtained in this comparative example using a centrifugal sedimentation type particle size distribution analyzer SA-CP3 (manufactured by Shimadzu Corporation). From the measurement results of the particle size distribution, it is confirmed that the calcium carbonate in the aqueous suspension obtained in the present comparative example has poor dispersibility as compared with Example 2.

Comparative Example 4 The aqueous calcium carbonate suspension having a pH of 11.3 and a solid concentration of 15% by weight obtained at 25 ° C. obtained in Example 2 was mixed with a 55% by weight press cake using a filter press. did. Since this product has no fluidity as it is and it is difficult to wet-pulverize it, 1.2% by weight of sodium polyacrylate is added to the solid content of calcium carbonate, and the mixture is stirred by a dissolver type disperser for 3 hours. After that, fluidity was maintained, and then wet pulverization was performed in the same manner as in Examples 1 and 2. The pH at 25 ° C before grinding was 1
0.5. Centrifugal sedimentation type particle size distribution analyzer SA-CP3 for calcium carbonate in the aqueous suspension obtained in this comparative example
Table 2 shows the results of the particle size distribution measurement by Shimadzu Corporation. From the measurement results of the particle size distribution, it is confirmed that the calcium carbonate in the aqueous suspension obtained in the present comparative example has poor dispersibility as compared with Example 2.

In Tables 1 and 2, A to E represent the following numerical values. A: pH value at 25 ° C. at the end of carbonation reaction B: pH value at 25 ° C. after stirring and / or standing of the obtained aqueous calcium carbonate suspension C: Calcium carbonate obtained by carbonation reaction Solid content concentration of water suspension (% by weight) D: Solid content concentration of concentrated calcium carbonate aqueous suspension (% by weight) E: 25 ° C. of concentrated calcium carbonate aqueous suspension to be wet-milled D25, D50, and D75 in Tables 1 and 2 indicate particle diameters of 25% by weight, 50% by weight, and 75% by weight, respectively, calculated from the coarse particle side in the particle size distribution measurement results.

[0025]

[Table 1]

[0026]

[Table 2]

APPLICATION EXAMPLE 1 The aqueous calcium carbonate suspension obtained in Examples 1 and 4 and Comparative Examples 1 and 2, and the aqueous calcium carbonate suspension obtained in Example 1 are further fed with carbon dioxide gas. By 2
After treating the fatty acid soda at 4.0% by weight with respect to a solution having a pH of 7.0 at 5 ° C. (abbreviated as Example 1 → pH 7), the solution was dehydrated with a filter press, and each of calcium carbonate was dried and pulverized. A powder was obtained. Using these five types of powders, a vinyl chloride paste sol was prepared according to the following formulation, and its viscosity and storage stability were examined. Table 3 shows the results. From the results shown in Table 3, the powder prepared using the aqueous calcium carbonate suspension of the example as a raw material has higher viscosity and thixotropic (T) than the calcium carbonate powder of the comparative example.
I value), confirming that the dispersibility is extremely good. Further, from Example 1 to pH 7, the storage stability was extremely good because the removal of the alkaline substance was almost completely performed. (Blend) Vinyl chloride paste resin (Zeon 121, manufactured by Nippon Zeon Co., Ltd.) 100 parts by weight DOP 100 parts by weight Polyamide (Henkel DSX140E, manufactured by Henkel Hakusui) 10 parts by weight Solvent (ester and hydrocarbon) 5 parts by weight 70 parts by weight of calcium carbonate sample

[0028]

[Table 3]

Application Example 2 The aqueous suspension of calcium carbonate obtained in Example 2 and Comparative Examples 3 and 4 was subjected to surface treatment with 3.0% by weight of fatty acid soda, and then dehydrated with a filter press to form a dry powder. As a result, a powder of calcium carbonate was obtained. Using these three kinds of powder, an acrylic resin paint is created with the following composition,
The gloss and the dispersibility (dispersion time until the dispersion particle size according to JIS K5400 becomes 10 μm or less) were examined. Table 4 shows the results. From the results in Table 4, the powder prepared using the aqueous calcium carbonate suspension of Example as a raw material
Compared with the calcium carbonate powder of the comparative example, it shows higher gloss and dispersibility, and is confirmed to be extremely good. (Blend) Acrylic resin 48.1 parts by weight Titanium white 20.9 parts by weight Calcium carbonate sample 10.2 parts by weight Thinner 20.8 parts by weight

[0030]

[Table 4]

[0030]

As described above, according to the present invention, precipitated calcium carbonate which is fine, has little secondary agglomeration, and has good dispersibility is industrially advantageously provided.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C01F 11/18

Claims (8)

(57) [Claims] When the precipitated calcium carbonate obtained by passing carbon dioxide gas through lime milk is wet-pulverized, the following a,
A method for producing a calcium carbonate fine particle dispersion, comprising using a calcium carbonate aqueous suspension which has been previously concentrated so as to satisfy each of the conditions b and c: a. PH (A) at the end of the carbonation reaction satisfies the following equation: Equation 8.0 ≦ A ≦ 10.0 (measured value at 25 ° C.) b. The pH (B) of the aqueous calcium carbonate solution obtained by stirring and / or allowing the aqueous suspension of calcium carbonate obtained by the above a to simultaneously satisfy the following expression: Expression 10.5 ≦ B (25 (Measured value at ° C) Formula BA ≧ 1.0 c. Concentrating the solid content concentration (C%) of the aqueous calcium carbonate suspension obtained in b above to a solid content concentration (D%) that simultaneously satisfies the following formula. Formula 1.2C ≦ D Formula 15 ≦ D ≦ 30 2. The method for producing a calcium carbonate fine particle dispersion according to claim 1, wherein the size of the limestone charged into the firing furnace when producing quicklime as a raw material of lime milk is 10 mm or less. 3. The activity of quicklime used is 60 ml (4N).
-HCl) or more. 4. The method for producing a calcium carbonate fine particle dispersion according to claim 1, wherein the chlorine ion concentration of water used for obtaining lime milk by hydrating quicklime is 200 ppm or less. 5. The method for producing a calcium carbonate fine particle dispersion according to claim 1, wherein the primary particle diameter of the precipitated calcium carbonate to be wet-pulverized is 0.2 μm or less. 6. pH of the aqueous calcium carbonate suspension after concentration
The method for producing a calcium carbonate fine particle dispersion according to claim 1, wherein (E) is prepared within the range of the following formula: Formula 10.0 ≦ E ≦ 11.0 (measured value at 25 ° C.) 7. pH of the aqueous calcium carbonate suspension after concentration
7. The method for producing a fine calcium carbonate dispersion according to claim 6, wherein (E) is prepared by passing carbon dioxide gas through and / or adding a calcium carbonate aqueous suspension obtained according to the condition (b) before wet grinding. Method. 8. An aqueous suspension of calcium carbonate after wet grinding.
The method for producing a calcium carbonate fine particle dispersion according to claim 1, wherein the pH is adjusted to 7.5 or less (measured value at 25 ° C) by passing carbon dioxide gas through.