CN111874935B - Preparation method of large-particle calcium carbonate - Google Patents
Preparation method of large-particle calcium carbonate Download PDFInfo
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- CN111874935B CN111874935B CN202010830098.9A CN202010830098A CN111874935B CN 111874935 B CN111874935 B CN 111874935B CN 202010830098 A CN202010830098 A CN 202010830098A CN 111874935 B CN111874935 B CN 111874935B
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/18—Carbonates
- C01F11/181—Preparation of calcium carbonate by carbonation of aqueous solutions and characterised by control of the carbonation conditions
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/18—Carbonates
- C01F11/185—After-treatment, e.g. grinding, purification, conversion of crystal morphology
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The invention discloses a preparation method of large-particle calcium carbonate, which comprises the following steps: preparing calcium hydroxide slurry, primarily carbonizing, secondarily carbonizing, repeatedly carbonizing again, thickening the slurry, carbonizing for the third time, preparing finished calcium carbonate slurry, centrifugally dewatering, drying, depolymerizing and crushing. According to the invention, the calcium hydroxide raw slurry is fully and completely prepared into primary calcium carbonate slurry by repeating the secondary carbonization, then the concentration of the slurry is increased by partially thickening the slurry to separate out crystal nuclei, and the slurry with the separated out crystal nuclei is fed back to the carbonization tank for further carbonization, so that the particles of the finally prepared calcium carbonate powder can reach more than 30 microns, and the requirements of related fields on large-particle calcium carbonate are met. The invention has the advantage of preparing the large-particle calcium carbonate.
Description
Technical Field
The invention relates to the field of calcium carbonate preparation, in particular to a preparation method of large-particle calcium carbonate.
Background
The light calcium carbonate powder is widely applied in the industrial field, but in some fields such as the medical field, large-particle calcium carbonate powder is needed to control the specific surface area of the calcium carbonate components and reduce the water absorption rate of the calcium carbonate so as to meet the special requirements of some preparation production.
However, the single crystal particles of light calcium carbonate produced by the conventional carbonization method are generally between 50 nanometers and 5 micrometers, and the requirement of large particles cannot be met.
Therefore, the existing carbonization method for preparing light calcium carbonate has the problem that large-particle calcium carbonate cannot be prepared.
Disclosure of Invention
The invention aims to provide a preparation method of large-particle calcium carbonate. The invention has the advantage of preparing large-particle calcium carbonate.
The technical scheme of the invention is as follows:
the preparation method of the large-particle calcium carbonate comprises the following steps: A. preparing calcium hydroxide slurry;
B. preliminary carbonization;
C. secondary carbonization;
D. and (3) repeating secondary carbonization: c, repeating the step C until the material level in the carbonization tank reaches 100 percent;
E. thickening slurry: taking a certain amount of slurry from the carbonization tank into a thickening tank, thickening the slurry, removing a dilute phase part containing crystal nuclei, and returning the residual concentrated phase part in the thickening tank into the carbonization tank;
F. and (3) third carbonization: adding the calcium hydroxide slurry into a carbonization tank, returning the material level in the carbonization tank to 100%, introducing carbon dioxide gas and stirring to reduce the pH value of the material in the carbonization tank to 7-8;
G. preparing finished calcium carbonate slurry;
H. dehydrating and drying;
I. depolymerizing and crushing.
The preparation method of the large-particle calcium carbonate is characterized by comprising the following steps: the preparation of the calcium hydroxide slurry in the step A comprises the following specific contents:
mixing and stirring calcium oxide and hot water to prepare calcium hydroxide crude slurry, and removing impurities from the calcium hydroxide crude slurry to obtain the calcium hydroxide slurry.
The preparation method of the large-particle calcium carbonate is characterized by comprising the following steps: the preliminary carbonization in the step B comprises the following specific contents:
adding the calcium hydroxide slurry into a carbonization tank until the material level in the carbonization tank reaches 20-50%, introducing carbon dioxide gas and stirring until the pH value of the material in the carbonization tank is reduced to 7-8.
The preparation method of the large-particle calcium carbonate is characterized by comprising the following steps: step C, secondary carbonization, which comprises the following specific contents:
and (3) continuously adding the calcium hydroxide slurry into the carbonization tank until the pH value of the materials in the carbonization tank reaches 13 or above, introducing carbon dioxide gas, and uniformly stirring until the pH value of the materials in the carbonization tank is reduced to 7-8.
The preparation method of the large-particle calcium carbonate is characterized by comprising the following steps: g, preparing the finished product of calcium carbonate slurry, which comprises the following specific contents:
and D, repeatedly executing the step E and the step F until the solid content of the slurry in the carbonization tank reaches 175-400 g/L and the pH value reaches 7-8, stopping introducing carbon dioxide gas and stopping stirring, and removing the finished calcium carbonate slurry.
The preparation method of the large-particle calcium carbonate is characterized by comprising the following steps: and H, dehydrating and drying, which comprises the following specific steps:
h1, centrifugal dehydration: dehydrating the finished calcium carbonate slurry by using a centrifugal machine to form a filter cake;
h2, drying: and drying the filter cake until the moisture content is below 1%.
The preparation method of the large-particle calcium carbonate is characterized by comprising the following steps: the solid content of the calcium hydroxide slurry in the step A is 100 g/L-250 g/L; the temperature of the hot water in the step A is 20-50 ℃; the temperature of the product A1 in the step A is 50-70 ℃.
The preparation method of the large-particle calcium carbonate is characterized by comprising the following steps: and E, enabling the solid content of the concentrated phase part remained in the thickening tank to reach more than 300 g/L.
The preparation method of the large-particle calcium carbonate is characterized by comprising the following steps: the filter cake in the step H1 has the water content of 20-22 percent and the density of 2.3-2.5 g/ml.
Compared with the prior art, the method has the advantages that the calcium hydroxide raw slurry is fully and completely prepared into the primary calcium carbonate slurry in a repeated secondary carbonization mode, then the concentration of the slurry is increased in a partial slurry thickening mode to separate out crystal nuclei, and the slurry with the separated out crystal nuclei is fed back into the carbonization tank to be further carbonized, so that the particles of the finally prepared calcium carbonate powder can reach more than 30 microns, and the requirements of related fields on large-particle calcium carbonate are met.
Therefore, the invention has the advantage of preparing the large-particle calcium carbonate.
Furthermore, the preparation process and the preparation process are improved to a certain extent only on the basis of the original calcium carbonate carbonization method, new calcium carbonate preparation is not required to be purchased, the purchase cost of equipment is saved, and the cost is lower.
The invention limits the process flow and the process parameters, and can stably and efficiently prepare the large-particle calcium carbonate meeting the requirements.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
The invention is further illustrated by the following figures and examples, which are not to be construed as limiting the invention.
Example 1. The preparation method of the large-particle calcium carbonate is shown in figure 1 and comprises the following steps: A. preparing calcium hydroxide slurry;
B. preliminary carbonization;
C. secondary carbonization;
D. and (3) repeating secondary carbonization: c, repeating the step C until the material level in the carbonization tank reaches 100 percent;
E. thickening slurry: taking a certain amount of slurry from the carbonization tank into a thickening tank, thickening the slurry, removing a dilute phase part containing crystal nuclei, and returning the residual concentrated phase part in the thickening tank into the carbonization tank;
F. and (3) third carbonization: adding the calcium hydroxide slurry into a carbonization tank, returning the material level in the carbonization tank to 100%, introducing carbon dioxide gas, and stirring to reduce the pH value of the material in the carbonization tank to 7-8;
G. preparing finished calcium carbonate slurry;
H. dehydrating and drying;
I. depolymerizing and crushing.
The preparation of the calcium hydroxide slurry in the step A comprises the following specific contents:
mixing and stirring calcium oxide and hot water to prepare calcium hydroxide crude slurry, and removing impurities from the calcium hydroxide crude slurry to obtain the calcium hydroxide slurry.
The preliminary carbonization in the step B comprises the following specific contents:
adding the calcium hydroxide slurry into a carbonization tank until the material level in the carbonization tank reaches 20-50%, introducing carbon dioxide gas and stirring until the pH value of the material in the carbonization tank is reduced to 7-8.
Step C, secondary carbonization, which comprises the following specific contents:
and (3) continuously adding the calcium hydroxide slurry into the carbonization tank until the pH value of the materials in the carbonization tank reaches 13 or above, introducing carbon dioxide gas, and uniformly stirring until the pH value of the materials in the carbonization tank is reduced to 7-8.
The preparation of the finished product calcium carbonate slurry in the step G comprises the following specific contents:
and D, repeatedly executing the step E and the step F until the solid content of the slurry in the carbonization tank reaches 175-400 g/L and the pH value reaches 7-8, stopping introducing carbon dioxide gas and stopping stirring, and removing the finished calcium carbonate slurry.
And H, dehydrating and drying, which comprises the following specific steps:
h1, centrifugal dehydration: dehydrating the finished calcium carbonate slurry by using a centrifugal machine to form a filter cake;
h2, drying: and drying the filter cake until the moisture content is below 1%.
The solid content of the calcium hydroxide slurry in the step A is 100 g/L-250 g/L; the temperature of the hot water in the step A is 20-50 ℃; the temperature of the product A1 in the step A is 50-70 ℃.
And E, enabling the solid content of the concentrated phase part remained in the thickening tank to reach more than 300 g/L.
The filter cake in the step H1 has the water content of 20-22 percent and the density of 2.3-2.5 g/ml.
Example 2. The preparation method of the large-particle calcium carbonate, as shown in figure 1, comprises the following steps: A. preparing calcium hydroxide slurry;
B. preliminary carbonization;
C. secondary carbonization;
D. and (3) repeating secondary carbonization: c, repeating the step C until the material level in the carbonization tank reaches 100 percent;
E. thickening slurry: taking a certain amount of slurry from the carbonization tank into a thickening tank, thickening the slurry, removing a dilute phase part containing crystal nuclei, and returning the residual concentrated phase part in the thickening tank into the carbonization tank;
F. and (3) third carbonization: adding the calcium hydroxide slurry into a carbonization tank, returning the material level in the carbonization tank to 100%, introducing carbon dioxide gas, and stirring to reduce the pH value of the material in the carbonization tank to 7;
G. preparing finished calcium carbonate slurry;
H. dehydrating and drying;
I. depolymerizing and crushing.
The preparation of the calcium hydroxide slurry in the step A comprises the following specific contents:
mixing and stirring calcium oxide and hot water to prepare calcium hydroxide crude slurry, and removing impurities from the calcium hydroxide crude slurry to obtain the calcium hydroxide slurry.
The preliminary carbonization in the step B comprises the following specific contents:
adding the calcium hydroxide slurry into a carbonization tank until the material level in the carbonization tank reaches 20-50%, introducing carbon dioxide gas and stirring until the pH value of the material in the carbonization tank is reduced to 7.
Step C, secondary carbonization, which comprises the following specific contents:
and (3) continuously adding the calcium hydroxide slurry into the carbonization tank until the pH value of the materials in the carbonization tank reaches 13 or above, introducing carbon dioxide gas, and uniformly stirring until the pH value of the materials in the carbonization tank is reduced to 7.
The preparation of the finished product calcium carbonate slurry in the step G comprises the following specific contents:
and D, repeatedly executing the step E and the step F until the solid content of the slurry in the carbonization tank reaches 350 g/L-400 g/L and the pH value reaches 7, stopping introducing carbon dioxide gas and stopping stirring, and removing the finished calcium carbonate slurry.
And H, dehydrating and drying, which comprises the following specific steps:
h1, centrifugal dehydration: dehydrating the finished calcium carbonate slurry by using a centrifugal machine to form a filter cake;
h2, drying: drying the filter cake until the water content is below 0.5 percent.
The solid content of the calcium hydroxide slurry in the step A is 150 g/L-250 g/L; the temperature of the hot water in the step A is 20-50 ℃; the temperature of the product A1 in the step A is 50-70 ℃.
And E, enabling the solid content of the concentrated phase part remained in the thickening tank to reach more than 400 g/L.
The filter cake in the step H1 has the water content of 20-22 percent and the density of 2.3-2.5 g/ml.
Claims (7)
1. The preparation method of the large-particle calcium carbonate is characterized by comprising the following steps:
A. preparing calcium hydroxide slurry;
B. preliminary carbonization;
C. secondary carbonization;
D. and (3) repeating secondary carbonization: c, repeating the step C until the material level in the carbonization tank reaches 100 percent;
E. thickening slurry: taking a certain amount of slurry from the carbonization tank into a thickening tank, thickening the slurry, removing a dilute phase part containing crystal nuclei, and returning the residual concentrated phase part in the thickening tank into the carbonization tank; the solid content of the concentrated phase part left in the thickening tank reaches more than 300 g/L;
F. and (3) carbonization for the third time: adding the calcium hydroxide slurry into a carbonization tank, returning the material level in the carbonization tank to 100%, introducing carbon dioxide gas, and stirring to reduce the pH value of the material in the carbonization tank to 7-8;
G. e, preparing finished calcium carbonate slurry, namely repeatedly executing the step E and the step F until the solid content of the slurry in the carbonization tank reaches 175-400 g/L and the pH value reaches 7-8, stopping introducing carbon dioxide gas and stopping stirring, and removing the finished calcium carbonate slurry;
H. dehydrating and drying;
I. depolymerizing and crushing.
2. The method of preparing large granular calcium carbonate according to claim 1, wherein: the preparation of the calcium hydroxide slurry in the step A comprises the following specific contents:
mixing and stirring calcium oxide and water to prepare calcium hydroxide crude slurry, and removing impurities from the calcium hydroxide crude slurry to obtain the calcium hydroxide slurry.
3. The method of preparing large granular calcium carbonate according to claim 1, wherein: the preliminary carbonization in the step B comprises the following specific contents:
adding the calcium hydroxide slurry into a carbonization tank until the material level in the carbonization tank reaches 20-50%, introducing carbon dioxide gas and stirring until the pH value of the material in the carbonization tank is reduced to 7-8.
4. The method of preparing large granular calcium carbonate according to claim 1, wherein: step C, secondary carbonization, which comprises the following specific contents:
and (3) continuously adding the calcium hydroxide slurry into the carbonization tank until the pH value of the material in the carbonization tank reaches 13 or above, introducing carbon dioxide gas and uniformly stirring until the pH value of the material in the carbonization tank is reduced to 7-8.
5. The method of preparing large granular calcium carbonate according to claim 1, wherein: and H, dehydrating and drying, which comprises the following specific steps:
h1, centrifugal dehydration: dehydrating the finished calcium carbonate slurry by using a centrifugal machine to form a filter cake;
h2, drying: and drying the filter cake until the moisture content is below 1%.
6. The method of preparing large granular calcium carbonate according to claim 2, wherein: the solid content of the calcium hydroxide slurry in the step A is 100 g/L-250 g/L; the water in the step A is hot water with the temperature of 20-50 ℃.
7. The method of preparing large granular calcium carbonate according to claim 5, wherein: the filter cake in the step H1 has the water content of 20-22 percent and the density of 2.3-2.5 g/ml.
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| CN115215339B (en) * | 2022-05-30 | 2023-10-10 | 湖北工业大学 | Method for preparing calcium carbonate carbonization crystal nucleus from carbide slag and carrying out solid waste and carbon fixation |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102659160A (en) * | 2012-05-02 | 2012-09-12 | 浙江省建德市正发碳酸钙有限公司 | Method for preparing low alkalinity calcium carbonate |
| CN102702795A (en) * | 2012-05-02 | 2012-10-03 | 石家庄市三兴钙业有限公司 | Preparation method of special nano calcium carbonate for polyurethane adhesives |
| CN103011226A (en) * | 2012-12-07 | 2013-04-03 | 池州凯尔特纳米科技有限公司 | Method for preparing nano calcium carbonate through nucleation and growth step by step |
| CN107416884A (en) * | 2017-09-30 | 2017-12-01 | 广西华洋矿源材料有限公司 | A kind of production method of high-quality superfine light calcium carbonate |
| CN110540226A (en) * | 2019-10-07 | 2019-12-06 | 浙江省建德市正发药业有限公司 | preparation method of high-density calcium carbonate powder |
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| CA2268614C (en) * | 1996-10-14 | 2007-03-27 | Fp-Pigments Oy | Precipitated calcium carbonate and method for the production thereof |
| JP4194288B2 (en) * | 2002-03-29 | 2008-12-10 | 日本製紙株式会社 | Method for producing calcium carbonate |
| CN109796632B (en) * | 2019-01-07 | 2020-11-17 | 卢氏国嵩莱纳米科技有限公司 | Preparation method of high-whiteness precipitated calcium carbonate with core-shell structure |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102659160A (en) * | 2012-05-02 | 2012-09-12 | 浙江省建德市正发碳酸钙有限公司 | Method for preparing low alkalinity calcium carbonate |
| CN102702795A (en) * | 2012-05-02 | 2012-10-03 | 石家庄市三兴钙业有限公司 | Preparation method of special nano calcium carbonate for polyurethane adhesives |
| CN103011226A (en) * | 2012-12-07 | 2013-04-03 | 池州凯尔特纳米科技有限公司 | Method for preparing nano calcium carbonate through nucleation and growth step by step |
| CN107416884A (en) * | 2017-09-30 | 2017-12-01 | 广西华洋矿源材料有限公司 | A kind of production method of high-quality superfine light calcium carbonate |
| CN110540226A (en) * | 2019-10-07 | 2019-12-06 | 浙江省建德市正发药业有限公司 | preparation method of high-density calcium carbonate powder |
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