CN109911924B

CN109911924B - Process for preparing calcium carbonate particles

Info

Publication number: CN109911924B
Application number: CN201711362572.4A
Authority: CN
Inventors: 张名惠; 柳万霞; 陈瑞燕; 徐恒文
Original assignee: TAIWAN CEMENT CORP; Industrial Technology Research Institute ITRI
Current assignee: TAIWAN CEMENT CORP; Industrial Technology Research Institute ITRI
Priority date: 2017-12-13
Filing date: 2017-12-18
Publication date: 2021-10-01
Anticipated expiration: 2037-12-18
Also published as: CN109911924A; TW201927696A; TWI636957B

Abstract

A method of preparing calcium carbonate particles comprising: feeding a calcium source and a carbon source at a concentration of 0.00015 mol/liter to 0.1 mol/liter to a hypergravity rotating disk reactor having rotating disks, mixing the calcium source and the carbon source at a speed of 1,000rpm to 5,000rpm to form a calcium carbonate slurry; and separating the liquid and the calcium carbonate particles from the calcium carbonate slurry, wherein the crystal morphology of the calcium carbonate particles comprises petal-shaped, chain-shaped or cubic shapes.

Description

Process for preparing calcium carbonate particles

Technical Field

The present disclosure relates to a method for preparing calcium carbonate particles, and more particularly, to a method for preparing calcium carbonate particles with different crystal appearances.

Background

Calcium carbonate of different crystal appearances has different uses and is applied to different industries. For example, calcium carbonate with a rosette crystal morphology can be used in the paper industry and the rubber, plastic and coating industries, wherein the paper industry has applications of providing whiteness, brightness, opacity, bulkiness, ink absorbency, and the like; in the rubber, plastic and coating industries, the coating has the functions of improving the porosity, oil absorption and hydrophilicity, water retention, comprehensive physical and mechanical properties and the like of the coating; prismatic calcium carbonate is useful in the paper industry and has utility in providing opacity, strength, and bulk; the acicular calcium carbonate can be used in magazine paper, rubber and plastic industries, wherein the acicular calcium carbonate has the purposes of improving the glossiness of the paper, the coverage rate of fibers and the like in the application of the magazine paper; in the rubber and plastic industry, the rubber reinforcing material has the functions of improving the rubber reinforcing effect, improving the impact resistance and bending strength of plastics and the like; the superfine chain calcium carbonate can be used in rubber, plastic, paper, paint and other industries, has the functions of improving the dispersibility of the rubber, the plastic, the paper and the paint, improving the activity of the fracture point of natural rubber, ensuring that the superfine chain calcium carbonate has better bonding capacity with a matrix, improving the reinforcing effect of synthetic rubber, serving as a reinforcing filler, partially replacing carbon black or white carbon black, and further reducing the production cost and other purposes; the spherical calcium carbonate can be used in rubber, paper making, printing ink, plastics and other industries, and has the functions of improving the dispersibility, the specific surface area, the coating and filling performances, improving the glossiness, the whiteness, the fluidity, the printing performance and the like; and the flaky calcium carbonate can be used in industries such as papermaking and coating, and has the purposes of improving ink absorption capacity, whiteness, printability, smoothness, glossiness, resistivity, elastic coefficient and the like.

As described above, calcium carbonate based on different crystal morphologies can be applied to different industries, and thus, calcium carbonate is required in a very large amount in the industry. For example, the demand for plastic calcium carbonate in china is greater than 100 million tons per year, and in the paper industry, the demand for calcium carbonate is greater than 300 million tons per year; the capacity of Taiwan plastics company in calcium carbonate is about 25 ten thousand tons per year; and the capacity of calcium carbonate produced by Speciality Minerals in the united states is 4000 ten thousand tons per year.

From the above, it is very important to prepare calcium carbonate with different crystal appearances in industry. The prior art uses different methods to control the crystal morphology of calcium carbonate, for example, increasing the reaction temperature for producing calcium carbonate, adding additives to the reaction solution, reverse microemulsion methods using a non-aqueous solvent such as methanol or using a surfactant, etc.; however, these methods have several disadvantages, for example, heating increases the manufacturing cost of calcium carbonate; the residue of the additive affects the purity and mechanical properties of the calcium carbonate product; and the use of a non-aqueous solvent and a surfactant increases the production cost of calcium carbonate, reduces the reaction rate, and causes environmental pollution, etc.

Therefore, it is an urgent problem in the art to develop a low-cost preparation method for improving the purity of the prepared calcium carbonate particles without using an additive such as a morphology controlling agent.

Disclosure of Invention

Drawings

FIG. 1 is a schematic cross-sectional view of a high gravity rotating disk reactor;

FIG. 2 shows petaloid calcium carbonate particles produced in accordance with an embodiment of the present invention;

FIG. 3 shows chain calcium carbonate particles produced by an example of the present invention;

FIG. 4 is a schematic representation of cubic calcium carbonate particles produced in accordance with an embodiment of the present invention; and

FIG. 5 shows the nano calcium carbonate particles prepared in the comparative example of the present invention.

Wherein, the reference numbers:

1 supergravity rotating disc reactor

10 casing

11 rotating disc

12 rotating shaft

13 infusion tube

13a, 13b sub-tubes

14 gas inlet

15 gas outlet

16 fluid outlet.

Detailed Description

The following description of the embodiments of the present invention is provided by way of specific examples, and other advantages and effects of the present invention will become apparent to those skilled in the art from the disclosure herein. The invention is capable of other and different embodiments and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the present invention.

As used in the specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise.

As used in the specification and the appended claims, the term "or" includes "and/or" is used in its sense unless the context clearly dictates otherwise.

The term "crystal morphology" as used herein refers to the appearance of an arrangement of particles; the chain-shaped crystal morphology means that nanoparticles with the length diameter of about 30 nanometers (nm) to 99 nanometers are connected with each other to form a chain-shaped morphology; the petal-shaped appearance is a petal-shaped appearance with the length of about 0.5 to 5 microns; and the cubic morphology is a cubic morphology with a side length of about 0.5 to 5 microns.

The term "nanoparticle" as used herein refers to a particle having a size between 1nm and 100 nm.

The invention provides a preparation method of calcium carbonate particles, which comprises the following steps: feeding a calcium source and a carbon source at a concentration of 0.00015 mol/liter to 0.1 mol/liter to a hypergravity rotating disk reactor having rotating disks, mixing the calcium source and the carbon source at a speed of 1,000rpm to 5,000rpm to form a calcium carbonate slurry; and separating the liquid and the calcium carbonate particles from the calcium carbonate slurry, wherein the crystal morphology of the calcium carbonate particles comprises petal-shaped, chain-shaped or cubic shapes.

Referring to FIG. 1, a schematic cross-sectional view of a high-gravity rotating disk reactor is shown, which is not intended to limit the form or structure of the high-gravity rotating disk reactor used in the present invention.

The high gravity rotating disk reactor 1 has a shell 10; a rotating disk 11 disposed in the housing 10, wherein the radius of the rotating disk 11 is 5 cm to 80 cm; a rotary shaft 12 connected to the rotary plate 11; an infusion tube 13 communicating with the rotary disk 11; a gas inlet 14, a gas outlet 15 and a fluid outlet 16 provided in the housing 10, wherein the liquid transport tube 13 may include two

sub-tubes

13a, 13 b. The calcium carbonate particles provided by the invention are prepared by feeding a calcium source with the concentration of 0.00015 mol/liter to 0.1 mol/liter to a rotating disc 11 through a liquid conveying pipe 13, rotating the rotating disc 11 at the rotating speed of 1,000rpm to 5,000rpm through a rotating shaft 12 of a supergravity rotating disc reactor 1, and enabling the calcium source to form a liquid film with the average thickness of 0.005 cm to 0.1 cm on the rotating disc 11; in addition, a carbon source is fed to the rotating disk 11 through a liquid transport tube 13 or a gas inlet 14, and the calcium source and the carbon source are mixed to form a calcium carbonate slurry.

In one embodiment, the calcium source comprises a calcium hydroxide slurry or an aqueous calcium chloride solution, and the calcium source is fed to the high-gravity rotating disk reactor 1 at a flow rate of 0.1 liters/minute to 1.0 liters/minute. More specifically, in one embodiment, the method for preparing calcium carbonate particles further comprises hydrating calcium oxide with water to obtain the calcium hydroxide slurry as the calcium source fed to the high-gravity rotating disc reactor with rotating discs, before feeding the calcium source and the carbon source to the high-gravity rotating disc reactor 1 with rotating discs 11. In one embodiment where the calcium source is a calcium hydroxide slurry, the calcium hydroxide slurry having a concentration of 0.00015 mol/liter to 0.1 mol/liter and a flow rate of 0.1 l/min to 0.35 l/min is fed to a high-gravity rotary disc reactor 1 having a rotary disc 11, and the carbon source fed to the rotary disc 11 is an aqueous solution of carbonic acid having a concentration of 0.005 mol/liter to 0.05 mol/liter and a pH of 3 to 5, and the aqueous solution of carbonic acid is fed to the high-gravity rotary disc reactor 1 at a flow rate of 0.5 l/min to 1.2 l/min, the calcium hydroxide slurry and the aqueous solution of carbonic acid are mixed at a rotation speed of 1,000rpm to 5,000rpm to form a calcium carbonate slurry, and cubic calcium carbonate particles are finally obtained, in this embodiment, after the calcium source and the carbon source are fed to the rotary disc 11 through

sub-tubes

13a, 13b, respectively, are initially mixed with each other to form a liquid film of calcium carbonate slurry.

In addition, to obtain the carbonated aqueous solution, the method for preparing calcium carbonate particles of the present invention may further comprise bubbling carbon dioxide gas in water to obtain the carbonated aqueous solution before feeding the calcium source and the carbon source to the high-gravity rotating disk reactor 1 having the rotating disk 11.

In the method for producing calcium carbonate particles of the present invention, in addition to using an aqueous carbonic acid solution as a carbon source, the carbon source may be carbon dioxide, a mixed gas containing carbon dioxide, or an aqueous solution of a carbonate salt. In addition, by controlling the phase or flow rate of the supplied carbon source, the crystal morphology of the resulting calcium carbonate particles can be changed.

In one embodiment, the carbon source is carbon dioxide, and the carbon dioxide is fed into the high-gravity rotating disk reactor 1 through a gas inlet 14, and the reaction residual gas is discharged through a gas outlet 15, wherein the carbon dioxide flow rate is 0.2L/min to 3.0L/min. If the carbon source is a mixed gas containing carbon dioxide, the concentration of the carbon dioxide is 10% to less than 100% by volume of the total mixed gas, and the flow rate of the mixed gas fed into the high-gravity rotating disk reactor 1 is 0.2 l/min to 50 l/min.

In a specific embodiment using carbon dioxide or a mixed gas containing carbon dioxide as a carbon source, the flow rate of the carbon dioxide may be 0.2 l/min to 1.2 l/min to obtain calcium carbonate particles as nanoparticles having a long diameter of 30 nm to 99 nm, the nanoparticles being arranged in a chain shape. When the flow rate of the carbon dioxide is adjusted to 1.3 l/min to 3.0 l/min, petaloid calcium carbonate particles can be obtained.

The calcium carbonate particles according to the present invention are produced by mixing the aforementioned calcium source and carbon source at various concentrations and flow rates at normal temperature, for example, 15 ℃ to 35 ℃ to form a calcium carbonate slurry, then passing the calcium carbonate slurry through the fluid outlet 16, and separating the liquid and the calcium carbonate particles from the calcium carbonate slurry by filtration or centrifugation to obtain calcium carbonate particles of different crystal morphologies, and the calcium carbonate slurry does not contain a crystal morphology controlling agent because the crystal morphology controlling agent is not used in the present invention. Therefore, the preparation method of the calcium carbonate particles can save energy cost and avoid influencing the purity and the mechanical property of the calcium carbonate particles due to additive residues. Furthermore, according to the preparation method of the calcium carbonate particles, the problems that the nucleation speed is too high and the crystal shape cannot be controlled due to the supergravity rotating disc reactor can be solved.

Example 1: preparation of petaloid calcium carbonate particles

0.0446 mol of calcium oxide is put into 1 liter of deionized water, and calcium hydroxide slurry is formed by stirring and mixing; the calcium hydroxide slurry and carbon dioxide gas were fed at flow rates of 0.25 l/min and 2 l/min, respectively, into a supergravity rotating disk reactor having a rotating disk at a rotation speed of 2,000rpm to form a liquid film having an average thickness of 0.03 cm on the rotating disk, and the carbon dioxide gas was mixed with the calcium hydroxide slurry on the rotating disk to form a calcium carbonate slurry. The calcium carbonate slurry was filtered to separate solid and liquid to obtain petaloid calcium carbonate particles as shown in fig. 2. The purity of the obtained petaloid calcium carbonate particles was about 95.3% as measured by thermogravimetric analysis and had a size of about 0.5 to 5 microns in length as observed by an electron microscope.

Example 2: preparation of calcium carbonate particles arranged in a chain

0.0446 mol of calcium oxide is put into 1 liter of deionized water, and calcium hydroxide slurry is formed by stirring and mixing; the calcium hydroxide slurry and carbon dioxide gas were fed at flow rates of 0.25 l/min and 1 l/min, respectively, into a supergravity rotating disk reactor having a rotating disk at a rotation speed of 2,000rpm, so that the calcium hydroxide slurry formed a liquid film having an average thickness of 0.03 cm on the rotating disk, and the carbon dioxide gas was mixed with the calcium hydroxide slurry on the rotating disk to form a calcium carbonate slurry. The calcium carbonate slurry was filtered to separate solid and liquid, to obtain calcium carbonate particles arranged in a chain as shown in fig. 3. The obtained chain-like arranged calcium carbonate particles have a purity of about 96.7% and have nanoparticles having a major diameter of about 30 nm to 99 nm.

Example 3: preparation of cubic calcium carbonate particles

0.0446 mol of calcium oxide is put into 1 liter of deionized water, and calcium hydroxide slurry is formed by stirring and mixing; carbon dioxide was also injected into the water using an aerator to form a carbonated aqueous solution of pH 3.8. The calcium hydroxide slurry and the aqueous carbonated solution were fed at flow rates of 0.25 l/min and 0.75 l/min, respectively, into a high-gravity rotating disc reactor having rotating discs at a rotation speed of 2,000rpm, and the calcium hydroxide slurry and the aqueous carbonated solution were mixed on the rotating discs to form a calcium carbonate slurry. The calcium carbonate slurry was filtered to obtain cubic calcium carbonate particles as shown in fig. 4. The cubic calcium carbonate particles obtained have a purity of about 97.7% and have a size of about 0.5 to 5 microns on a side.

Comparative example 1: preparation of nano calcium carbonate particles

Adding 0.178 mol of calcium oxide into 1 liter of deionized water, and stirring and mixing to form calcium hydroxide slurry; feeding the calcium hydroxide slurry and carbon dioxide gas into a supergravity rotating disc reactor with a rotating disc at a rotating speed of 2,000rpm at flow rates of 1.1 liter/min and 2 liters/min, respectively, so that the calcium hydroxide slurry forms a liquid film with an average thickness of 0.055 cm to 0.067 cm on the rotating disc, and the carbon dioxide gas is mixed with the calcium hydroxide slurry on the rotating disc to form the calcium carbonate slurry. The calcium carbonate slurry was filtered to separate solid and liquid to obtain nano calcium carbonate particles as shown in fig. 5.

Comparing examples 1 to 3 and comparative example 1, calcium carbonate particles of different crystal morphologies according to the present invention were prepared by mixing a calcium hydroxide slurry obtained by hydration reaction using a low concentration of calcium source at a normal temperature, for example, 15 ℃ to 35 ℃, with a carbon source through a super-gravity rotating disc reactor, and obtaining calcium carbonate particles of different crystal morphologies, such as petal-shaped, chain-shaped, or cubic-shaped, with high purity in a continuous production manner by adjusting the flow rates of the calcium source and the carbon source and the rotation speed of the rotating disc without adding any additives, such as a morphology controlling agent, an unsaturated fatty acid, or a dispersing agent. In addition, in the preparation method of calcium carbonate particles with different crystal appearances, calcium oxide used as a calcium source can be taken from a product obtained after limestone is calcined, and carbon dioxide used as a carbon source can be recycled from air, so that the preparation method not only provides a low-cost preparation method, but also achieves the effects of protecting earth resources and reducing environmental pollution by recycling wastes. In addition, the invention avoids influencing the purity of calcium carbonate particles and the mechanical property thereof due to additive residues.

The present invention is capable of other embodiments, and various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method of preparing calcium carbonate particles, comprising:

feeding a calcium source and a carbon source at a concentration of 0.00015 to 0.1 mol/l into a super-gravity rotating disc reactor having rotating discs, mixing the calcium source and the carbon source at 15 to 35 ℃ at a speed of 1,000 to 5,000rpm to form a calcium carbonate slurry, wherein the calcium source is fed into the super-gravity rotating disc reactor at a flow rate of 0.1 to 1.0 l/min, and the calcium carbonate slurry does not contain a morphology control agent; and

separating the liquid and the calcium carbonate particles from the calcium carbonate slurry, wherein the calcium carbonate particles have a crystal morphology comprising petal-like, chain-like, or cubic shapes.

2. The method of producing calcium carbonate particles according to claim 1, wherein the calcium source is fed onto the rotating disk, and the average liquid film thickness is 0.005 cm to 0.1 cm.

3. The method of producing calcium carbonate particles according to claim 1, wherein the calcium source comprises a calcium hydroxide slurry or an aqueous calcium chloride solution.

4. The method of preparing calcium carbonate particles according to claim 3, further comprising hydrating calcium oxide with water to obtain the calcium hydroxide slurry as the calcium source fed to the high-gravity rotating disc reactor with rotating discs, before feeding the calcium source and the carbon source to the high-gravity rotating disc reactor with rotating discs.

5. The method for producing calcium carbonate particles according to claim 1, wherein the carbon source comprises carbon dioxide, a mixed gas containing carbon dioxide, an aqueous solution of carbonic acid, or an aqueous solution of carbonic acid salt.

6. The method of preparing calcium carbonate particles according to claim 5, wherein the carbon source is carbon dioxide and the carbon dioxide is fed to the high-gravity rotating disk reactor at a flow rate of 0.2L/min to 3.0L/min.

7. The method of preparing calcium carbonate particles according to claim 5, wherein the carbon source is a mixed gas containing carbon dioxide, and the concentration of carbon dioxide is 10% to less than 100% based on the total volume of the mixed gas, and the flow rate of the mixed gas fed into the high-gravity rotating disk reactor is 0.2L/min to 50L/min.

8. The method of preparing calcium carbonate particles according to claim 6, wherein the flow rate of the carbon dioxide fed into the high-gravity rotating disk reactor is 0.2L/min to 1.2L/min, and the calcium carbonate particles obtained are nanoparticles having a long diameter of 30 nm to 99 nm, which are arranged in a chain shape.

9. The method for preparing calcium carbonate particles according to claim 7, wherein the flow rate of the mixed gas fed into the high-gravity rotating disk reactor is 0.2L/min to 1.2L/min, and the calcium carbonate particles obtained are nanoparticles having a long diameter of 30 nm to 99 nm, which are arranged in a chain shape.

10. The method of claim 6, wherein the carbon dioxide is fed to the high-gravity rotating disk reactor at a flow rate of 1.3L/min to 3.0L/min, and the calcium carbonate particles are obtained in the shape of petals.

11. The method of claim 7, wherein the flow rate of the mixed gas fed into the high-gravity rotating disk reactor is 1.3L/min to 3.0L/min, and the calcium carbonate particles are obtained in the shape of petals.

12. The method of preparing calcium carbonate particles according to claim 5, wherein the carbon source is an aqueous carbonated solution having a concentration of 0.005 to 0.05 mol/l and a pH of 3 to 5, and the flow rate at which the aqueous carbonated solution is fed to the super-gravity rotating disk reactor is 0.5 to 1.2 l/min.

13. The method of claim 12, wherein the calcium source is fed to the high-gravity rotating disk reactor at a flow rate of 0.1 l/min to 0.35 l/min, and the resulting calcium carbonate particles are in the form of cubes.

14. The method of preparing calcium carbonate particles according to claim 12 or 13, further comprising bubbling carbon dioxide gas in water to obtain the carbonated aqueous solution before feeding the calcium source and the carbon source to the high gravity rotating disc reactor having rotating discs.

15. The process for preparing calcium carbonate particles according to claim 1, wherein the radius of the rotating disk is from 5 cm to 80 cm.

16. The method for producing calcium carbonate particles according to claim 1, wherein the liquid and the calcium carbonate particles are separated from the calcium carbonate slurry by filtration or centrifugation.