JP4574517B2 - Method for producing vaterite disk-like calcium carbonate - Google Patents

Description

The present invention relates to a method for producing calcium carbonate having a disk shape. More specifically, the present invention relates to a method for efficiently producing calcium carbonate in the form of a vaterite disk having a monodispersed and controlled particle size containing almost no impurities in a short time and with a simple operation. It is.

The carbon dioxide method is widely adopted as an industrial production method for calcium carbonate. The production process by this production method includes the calcination of limestone, the digestion and carbonation process, the foreign matter removal process, the cleaning of limestone calcined exhaust gas, and the petrified emulsion. The process of introduction into the system is necessary, and complicated processes and devices are necessary. Moreover, there is a problem of impurities mixed in from limestone, and its use is limited to industrial products or foods. In order to expand the use, it is necessary to go through a process for purifying lime milk that removes impurities from limestone, which complicates the process and apparatus for that purpose and has the disadvantage of increasing manufacturing costs.
On the other hand, a solution method is also known as a method for producing calcium carbonate, and this solution method has the advantage of eliminating impurities, simplifying the production apparatus, and reducing the production cost. However, the shape of calcium carbonate produced by the solution method that has been proposed so far is almost spherical and has limited applications.

As a conventional method for producing calcium carbonate having a plate shape and an oval shape, the following has been proposed .
( 1 ). Journal of Gypsum Lime Society, “Gypsum and Lime” No. 196 (hereinafter referred to as Non-Patent Document 1) proposes a method of carbonating hexagonal plate-like calcium hydroxide at high temperature with carbon dioxide gas.
( 2 ). JP 61-219717 (hereinafter, referred to as Patent Document 1) is a "hexagonal plate form was basic calcium of more than 200 ° C. carbonate temperature, the carbonated in contact with carbon dioxide hexagonal plate-like calcium carbonate "Manufacturing method" has been proposed .
( 3 ). Japanese Patent Laid-Open No. 11-314915 (hereinafter referred to as Patent Document 2) states that “a carbon dioxide gas is introduced into a methanol suspension containing a specific amount of quicklime and / or slaked lime and a specific amount of water and specified during the carbonation reaction. At this point, the temperature in the reaction system is adjusted to a specific temperature, and the carbonation reaction is performed by specifying the time for the conductivity in the reaction system to reach a specific value from the start of the carbonation reaction. Has been proposed .
( 4 ). Patent No. 3362239 (hereinafter referred to as Patent Document 3) states that “a carbonation reaction is carried out in the presence of an organic amine compound under the condition of introducing basic carbon carbonate into hexagonal plate form by introducing carbon dioxide into lime milk. "how to synthesize disk-shaped calcium carbonate it has been proposed by.
( 5 ). JP 1-108117 (hereinafter, referred to as Patent Document 4), the "method of manufacturing vaterite-type spherical calcium carbonate calcium ion solution and carbonate ion solution is mixed and stirred" is proposed.

Japanese Patent Laid-Open No. 61-219717 JP 11-314915 A Japanese Patent No. 3362239 Japanese Patent Laid-Open No. 1-108117 N. Yasue, Yoshiaki Tsuchida, Kenichi Tanaka, Yasuo Arai, Heat carbonation of hexagonal plate-like calcium hydroxide and properties of carbonate, gypsum and lime, Japan, Gypsum Lime Society, 1986, No. 196,121

However, Non-Patent Document 1 and Patent Document 1, calcium and basic calcium carbonate hydroxide hexagonal plate-like solid form by contacting the reaction with carbon dioxide gas, for generating a hexagonal plate-like calcium carbonate is carbonated It requires a large amount of heat energy, and further requires a long time for carbonation, resulting in high costs and not suitable for industrial production. Furthermore, the form of calcium carbonate produced is plate-like, which is different from the disk-like form of the present invention.
In addition , the production method of Patent Document 2 is a method of adding a large amount of alcohol to lime milk and carbonating with carbon dioxide gas, which increases the cost of equipment and costs for alcohol recovery, and at the same time, impurities in lime milk derived from limestone This makes it unsuitable for the Japanese Pharmacopoeia and food additive standards and is not suitable for industrial production. Furthermore, the form of calcium carbonate to be produced is spherical or elliptical, and is different from the disk-like form of the present invention.
In addition , the production method of Patent Document 3 performs carbonation under the conditions for producing hexagonal plate-like basic calcium carbonate when carbon dioxide gas is introduced into lime milk, and adds an amine compound when producing hexagonal plate-like basic calcium carbonate. Since the amine compound is adsorbed on the calcium carbonate surface, it becomes unsuitable for the Japanese Pharmacopoeia and food additive standards, and the range of use is limited. Furthermore, the form of calcium carbonate produced is plate-like, which is different from the disk-like form of the present invention.
Furthermore , although the production method of Patent Document 4 is a reaction of a soluble calcium salt and a soluble carbonate, it is a vaterite type crystal because of rapid mixing, but the particle form is spherical and is different from the present invention.

  The present invention aims to dramatically expand the uses, and in industrial use, the dispersibility is improved and the physical properties are improved from the plate-like form due to the improvement of conventional processing steps and the increased usage. The purpose is to control the particle size of the calcium carbonate, which is improved and has a compounding effect.

Further, the present invention does not use a large amount of heat energy for the carbonation reaction, and further does not use an organic solvent such as alcohol, so that it does not require equipment and operation costs for recovering the organic solvent, resulting in high costs. In addition, it is suitable for industrial production with an inexpensive manufacturing method, and since no organic amine compound is added as an additive, there is no adsorption of the organic amine compound to the produced calcium carbonate, and the soluble calcium salt as a raw material. Since soluble carbonates and high-purity carbonates are easily available from the market at low cost, the obtained calcium carbonate is compatible with Japanese Pharmacopoeia and food additive standards. the method facing the aqueous solution for the industrial production of to drop the reaction, it is an object to synthesize a vaterite-type disc-shaped calcium carbonate.
In addition , the present invention is a monodispersed, vaterite-type disk-like calcium carbonate that can be used in a wide range of fields with a controlled particle size in a short time, with simple equipment and operation, efficiently and economically. The object is to provide an industrially advantageous process.

As a result of diligent research, the present inventor has made use of the advantage of the simplicity of the solution method in order to achieve the above-mentioned problem, and the soluble calcium salt is soluble carbonate or soluble carbonate is dissolved in the temperature condition and the dropping rate. A novel disk-shaped vaterite-type calcium carbonate production method has been realized by performing a carbonation reaction under control.
The soluble calcium salt of the present invention includes calcium chloride, calcium bromide, calcium iodide, calcium nitrate, calcium nitrite, calcium formate, calcium acetate, calcium ascorbate, calcium lactate, calcium citrate, and calcium gluconate. If it is soluble, it may be used alone or in combination of two or more.
The soluble carbonate may be used alone or in combination of two or more, as long as it is soluble in sodium carbonate, potassium carbonate or ammonium carbonate water.
In the present invention, the concentration of each soluble calcium salt and soluble carbonate is 0.1 to 1 mol / L, preferably 0.3 to 0.7 mol / L, and the reaction temperature is 5 to 50 ° C., preferably Is preferably 20 to 45, and the dropping time is 0.1 to 10 hours, preferably 0.5 to 4 hours, more preferably 0.5 to 2 hours .
The method for producing the vaterite-type disk-like calcium carbonate of the present invention is characterized in that a soluble calcium salt aqueous solution is dropped into a soluble carbonate aqueous solution or a soluble carbonate aqueous solution is dropped into a soluble calcium salt aqueous solution. The particle diameter of the calcium carbonate to be produced is 1-20 μm and vaterite-type calcium carbonate having a disk shape.

In the present invention, when the solution concentration is less than 0.1 mol / L, since the concentration of the produced calcium carbonate is low, it takes time for filtration and drying, resulting in poor productivity and not industrial. On the other hand, when the solution concentration exceeds 1 mol / L, the reaction becomes non-uniform and the production of calcite type cubic calcium carbonate increases, resulting in a mixture of vaterite disk-like calcium carbonate and calcite type cubic calcium carbonate. A homogeneous reaction product is obtained.
Furthermore, when the dropping time is less than 0.1 hour, it becomes the same as the mixing reaction, and the generation of spherical particles increases and becomes non-uniform. On the other hand, when the dropping time exceeds 10 hours, the production of calcite cubic calcium carbonate increases and becomes non-uniform.

As described above, the method for producing calcium carbonate according to the present invention can be obtained by reacting a soluble carbonate aqueous solution with a soluble calcium salt aqueous solution or a soluble calcium salt aqueous solution with a soluble carbonate aqueous solution at a constant concentration, reaction temperature and dropping time. Thus, the vaterite type disk-like calcium carbonate can be generated.
The method for producing calcium carbonate according to the present invention does not require special heat energy as compared with the hexagonal plate-like, disc-like or oval spherical calcium carbonate production methods that have been announced so far. the organic solvent of the organic solvent recovery costs and special recovery unit in order not to use is not required, and the higher the added pure calcium carbonate for unnecessary organic amine compound is a special additives, furthermore The produced vaterite disk-like calcium carbonate is monodispersed and the particle size is controlled, so that its application is dramatically expanded and can be used in a wide range of business fields.
Moreover, the vaterite disk-like calcium carbonate production method of the present invention is an efficient, economical and industrially advantageous production method because the applicable production apparatus is simple and the operation is simple.

The present invention is a method for producing a vaterite-type disk-like calcium carbonate, characterized in that a soluble carbonate aqueous solution or a soluble calcium salt aqueous solution is dropped into a soluble calcium salt aqueous solution or a soluble carbonate aqueous solution to perform a carbonation reaction.
An aqueous solution of a highly pure water-soluble calcium salt and / or hydrate thereof is prepared at a concentration of 0.1 to 1 mol / L, preferably 0.3 to 0.7 mol / L. Separately, an aqueous solution having a concentration of 0.1 to 1 mol / L, preferably 0.3 to 0.7 mol / L, of a high-purity water-soluble carbonate and / or hydrate thereof is prepared.
If the solution concentration is less than 0.1 mol / L, a large amount of cubic calcium carbonate is produced, and at the same time, the concentration of calcium carbonate is low, so that it takes time for filtration and drying, resulting in poor productivity and not industrial. On the other hand , when the solution concentration is less than 0.1 mol / L, the concentration of the produced calcium carbonate is low, so it takes time for filtration and drying, resulting in poor productivity and not industrial. When the solution concentration exceeds 1 mol / L, the reaction becomes heterogeneous and the production of calcite-type cubic calcium carbonate increases, resulting in a mixture of vaterite disk-like calcium carbonate and calcite-type cubic calcium carbonate. Product. At this time, the molar ratio of calcium ion to carbonate ion is preferably 1: 1, and if the molar ratio is different, unreacted calcium ion or carbonate ion remains in the solution, and the effective resources are discarded. Not.

  When the dropping time is 0.5 to 2 hours and the dropping time is less than 0.1 hour, the production of vaterite-type spherical particles is increased in the same manner as the mixing reaction. A mixture is formed and becomes non-uniform. In addition, when the dropping time exceeds 4 hours, the generation of calcite-type cubic calcium carbonate is gradually increased, and a mixture of vaterite-type disk-like calcium carbonate and calcite-type cubic calcium carbonate is formed, resulting in spread of non-uniformity. When the dropping time exceeds 10 hours, calcite-type cubic calcium carbonate is mainly produced.

  The reaction temperature is in the range of 5 to 50 ° C., buterite type disk-like calcium carbonate is produced, but the reaction temperature is optimally 30 to 45 ° C. The produced vaterite type disk-like calcium carbonate has a particle diameter of 1 to 20 μm. The vaterite content by X-ray diffraction is 90% or more. When the reaction temperature is 50 ° C. or higher, the production of aragonite needle-like or columnar calcium carbonate increases, resulting in a non-uniform product. When the temperature is 20 ° C. or less, aggregates of the vaterite type disk-like calcium carbonate increase. However, when stirring is performed using ultrasonic waves, the vaterite content is 60% or more even when the reaction temperature is 20 ° C. or less. Generate. When the reaction temperature is less than 5 ° C., almost no vaterite-type disk-like calcium carbonate is produced, and it is not economical because a large amount of heat energy is used for cooling.

The use of calcium salts or carbonates that are sparingly or insoluble in water, or the use of either calcium salts or carbonates with soluble salts and the other with sparingly soluble or insoluble salts, the reaction does not go well, but a vaterite type Discotic calcium carbonate is not produced.
Hereinafter, although an example and a comparative example of the present invention explain, the present invention is not limited at all by these.

7.36 g of reagent-grade calcium chloride dihydrate is dissolved in 200 ml of warm water at 40 ° C. Reagent-grade sodium carbonate 5.30 g was dissolved in 100 ml, and this solution was continuously added dropwise over 1 hour while stirring the calcium chloride solution. After completion of dropping, the mixture was filtered, washed with water, and then dried at 110 ° C. for 12 hours. The result of measuring the powder X diffraction of this dry solid is shown in FIG. As a result of analyzing the spectrum, the content rate of vaterite was 92%. The results of observation with a scanning electron microscope are shown in FIG. It was a circular plate-shaped crystals of particle size 5~10μm from a photograph. As a result of chemical analysis, the content of calcium carbonate was 99.9% or more.
[Comparative Example 1]

  The same procedure as in Example 1 was repeated except that the sodium carbonate solution was stirred and mixed with the calcium chloride solution within 1 minute. As a result of measuring the powder X diffraction of the obtained dry solid, the content rate of vaterite was 90%. The results of scanning electron microscope observation are shown in FIG. The particle size was 2-4 μm spherical vaterite and cubic calcite. As a result of chemical analysis, the content of calcium carbonate was 99.9% or more.

The reaction temperature was 15 ° C., and the same procedure as in Example 1 was performed except that an ultrasonic stirrer was used for stirring. As a result of measuring powder X diffraction of the obtained dry solid, vaterite and calcite were mixed, and the content rate of vaterite was 94%. As a result of observation with a scanning electron microscope, the particle diameter was a disk-shaped form having a diameter of 3 to 6 μm. As a result of chemical analysis, the content of calcium carbonate was 99.9% or more.
[Comparative Example 2]

  Example 1 was repeated except that the reaction temperature was 15 ° C. As a result of measuring the powder X diffraction of the obtained dry solid, the content rate of the vaterite was 92%. As a result of observation with a scanning electron microscope, a disk-like form having a primary particle diameter of 1 to 10 μm aggregated to form an aggregated state of 10 to 15 μm. As a result of chemical analysis, the content of calcium carbonate was 99.9% or more.

  The same procedure as in Example 1 was conducted except that 3.68 g of calcium chloride dihydrate and 5.90 g of calcium nitrate tetrahydrate were dissolved in 200 ml of warm water at 40 ° C. As a result of measuring the powder X diffraction of the obtained dry solid, the content rate of vaterite was 94%. As a result of observation with a scanning electron microscope, the particle diameter was a disk-shaped form having a diameter of 3 to 6 μm. As a result of chemical analysis, the content of calcium carbonate was 99.9% or more.

11.04 g of reagent-grade calcium chloride dihydrate is dissolved in 200 ml of warm water at 30 ° C. Reagent-grade sodium carbonate (10.37 g) was dissolved in 100 ml, and this solution was continuously added dropwise over 1 hour while stirring the calcium chloride solution. After completion of dropping, the mixture was filtered, washed with water, and then dried at 110 ° C. for 12 hours. As a result of measuring the powder X diffraction of this dry solid, the content rate of the vaterite was 90%. Scanning electron microscopic observation of the results was a circular plate-shaped crystals of particle size 4-8 [mu] m. As a result of chemical analysis, the content of calcium carbonate was 99.9% or more.
[Comparative Example 3]

  The same procedure as in Example 1 was conducted except that the reaction temperature was 70 ° C. As a result of measuring the diffraction of the powder of the obtained dry solid, diffraction was found to be mainly composed of vaterite, a small amount of vaterite and calcite were recognized, and the content of aragonite was 91%. As a result of observation with a scanning electron microscope, The particle size was a mixture of needles, columns, cubes, and disks having a diameter of 1 to 10 μm.

The same procedure as in Example 1 was performed except that the dropping time was 4 hours. As a result, a 77% content of the vaterite, scanning electron microscopy results, the particle size was circular plate-like 8 to 15 m.

(Example 1) which is an X-ray-diffraction figure of vaterite type disk-like calcium carbonate. FIG. 2 is a scanning electron micrograph showing the particle structure of vaterite-type disk-like calcium carbonate (Example 1). FIG. 2 is a scanning electron micrograph showing the particle structure of vaterite-type spherical calcium carbonate and calcite-type cubic calcium carbonate (Comparative Example 1).

Claims (4)

Soluble calcium salt aqueous solution or a soluble carbonate salt solution, a soluble carbonate salt aqueous solution or a soluble calcium salt solution, each concentration of 0.1-1 mol / L, the dropping time was 0.5-4 hours, a further, A method for producing a vaterite-type disk-like calcium carbonate, characterized in that the reaction temperature is dropped at 5 to 50 ° C. to cause a carbonation reaction. The vaterite type according to claim 1 , wherein at least one selected from sodium carbonate, potassium carbonate or ammonium carbonate as a soluble carbonate and at least one selected from calcium chloride, calcium nitrate or calcium lactate as a soluble calcium salt are reacted. A method for producing discotic calcium carbonate. The method for producing a vaterite disk-shaped calcium carbonate according to claim 1 or 2 , wherein a soluble calcium salt aqueous solution is dropped into the soluble carbonate aqueous solution , or a soluble carbonate aqueous solution is dropped into the soluble calcium salt aqueous solution. The method for producing a vaterite disk-like calcium carbonate according to claim 1 , wherein the particle diameter of the vaterite disk-like calcium carbonate is 1 to 20 µm.