Large-particle-size high-purity precipitated calcium carbonate and synthesis method thereof

Abstract

The invention belongs to the technical field of inorganic material preparation, and relates to large-particle-size high-purity precipitated calcium carbonate and a synthesis method thereof. The synthesis method of the large-particle-size high-purity precipitated calcium carbonate comprises the following steps: preparing a calcium salt solution with the concentration of 0.4-4.0 mol / L; preparing a carbonate solution with the concentration of 0.8 to 3.2 mol / L; adding 0.3-3 m < 3 > of pure water into the synthesis kettle; heating the calcium salt solution to 10-70 DEG C, heating the carbonate solution to 10-30 DEG C, and continuously injecting into a synthesis kettle while stirring to obtain calcium carbonate slurry; the flow of the calcium salt solution is 0.16-4.0 m < 3 > / h; the flow of the carbonate solution is 0.08-5.0 m < 3 > / h; the stirring speed is 24 to 85 rpm; the reaction temperature is 10-55 DEG C; and filtering, washing and drying the calcium carbonate slurry to obtain large-particle-size high-purity precipitated calcium carbonate. The large-particle-size high-purity calcium carbonate with the particle size of 20-115 microns can be prepared only by adjusting parameters such as the concentration, the pH value, the temperature, the flow rate, the stirring rate and the reaction temperature of synthetic reaction materials, and the requirements of the fields such as preparation of optical glass and high-purity calcium salt for the particle size of the high-purity calcium carbonate are met.

Description

Technical Field

[0001] The invention belongs to the technical field of inorganic material preparation, and in particular relates to large-particle high-purity precipitated calcium carbonate and a synthesis method thereof. Background Art

[0002] High-purity calcium carbonate is widely used in electronic ceramics, pharmaceutical raw materials, cosmetics, optical glass, fluorescent materials, experimental aids, and intermediates for the preparation of high-purity calcium salts. However, in traditional manufacturing, high-purity calcium carbonate is a vague concept. For example, when the iron impurity content is controlled to be lower and the calcium carbonate content reaches more than 98%, some people call it high-purity calcium carbonate. But in the field of high-end material applications, this is far from meeting the high-purity standard.

[0003] At present, the common high-purity calcium carbonate preparation process is to mix calcium chloride solution and soluble carbonate to react, and the particle size of the prepared calcium carbonate is mostly below 40μm and difficult to exceed 60μm. This limits its application in the field of optical glass and high-purity calcium salt preparation.

[0004] The Chinese invention patent application with publication number CN115231601A discloses a method for preparing large-particle calcium carbonate particles for injection. Although the method can synthesize large-particle calcium carbonate with a particle size of 25 to 100 μm, a macromolecular nucleating agent needs to be added in the preparation process. The addition of the nucleating agent may affect the impurity content of the calcium carbonate product, thereby affecting the application of the calcium carbonate product.

[0005] Therefore, there is an urgent need to develop a novel method for synthesizing large-particle-size high-purity precipitated calcium carbonate in this field. Summary of the invention

[0006] In view of the defects of the prior art, the present invention provides a large-particle-size high-purity precipitated calcium carbonate and a synthesis method thereof.

[0007] The present invention is achieved through the following technical solutions:

[0008] A method for synthesizing large-particle-size high-purity precipitated calcium carbonate comprises:

[0009] (1) dissolving a water-soluble calcium salt in pure water to obtain a calcium salt solution with a concentration of 0.4 to 4.0 mol / L;

[0010] (2) dissolving a water-soluble carbonate in pure water to obtain a carbonate solution having a concentration of 0.8 to 3.2 mol / L;

[0011] (3) Add 0.3-3 m 3 Pure water, start stirring, stirring speed is 24~85rpm;

[0012] (4) heating the calcium salt solution to 10-70° C. and the carbonate solution to 10-30° C., and then continuously injecting the solution into the synthesis reactor under stirring to react and obtain calcium carbonate slurry;

[0013] Wherein, the flow rate of the calcium salt solution is 0.16~4.0m 3 / h; the flow rate of the carbonate solution is 0.08~5.0m 3 / h; the stirring rate is 24-85rpm; the reaction temperature is 10-55°C;

[0014] (5) The calcium carbonate slurry is filtered, washed and dried to obtain large-particle-size high-purity precipitated calcium carbonate.

[0015] In the above-mentioned method for synthesizing large-particle high-purity precipitated calcium carbonate, the water-soluble calcium salt includes one or more of calcium chloride and calcium nitrate.

[0016] In the above-mentioned method for synthesizing large-particle high-purity precipitated calcium carbonate, the water-soluble carbonate includes one or more of ammonium carbonate and sodium carbonate.

[0017] In the above-mentioned method for synthesizing large-particle high-purity precipitated calcium carbonate, the pH regulator is one or more of hydrochloric acid, nitric acid, ammonia water, and calcium hydroxide.

[0018] In the above-mentioned method for synthesizing large-particle high-purity precipitated calcium carbonate, the concentration of the calcium salt solution is 1.5-2.5 mol / L and the pH is 3-11; the concentration of the carbonate solution is 1.5-2.5 mol / L.

[0019] In the above-mentioned method for synthesizing large-particle high-purity precipitated calcium carbonate, the amount of pure water added to the synthesis kettle is 1.0 to 2.0 m 3 , the stirring rate is 40-65rpm.

[0020] In the above-mentioned method for synthesizing large-particle high-purity precipitated calcium carbonate, in step (4), the heating temperature of the calcium salt solution is 30-50°C; the heating temperature of the carbonate solution is 16-24°C.

[0021] In the above-mentioned method for synthesizing large-particle high-purity precipitated calcium carbonate, in step (4), the flow rate of the calcium salt solution is 1.2 to 2.0 m 3 / h; the flow rate of the carbonate solution is 1.5 to 3.0m 3 / h; the stirring rate is 40-65rpm; the reaction temperature is 25-40°C.

[0022] A large-particle-size high-purity precipitated calcium carbonate is prepared by the above-mentioned synthesis method.

[0023] The above-mentioned large-particle high-purity precipitated calcium carbonate is characterized in that the particle size of the precipitated calcium carbonate is 20 to 115 μm.

[0024] The technical solution of the present invention has the following beneficial effects:

[0025] The present invention can prepare high-purity calcium carbonate with a large particle size / ultra-large particle size and a particle size of 20 to 115 μm by adjusting parameters such as the concentration, pH, temperature, flow rate, stirring rate, reaction temperature and the like of the synthesis reaction materials without adding a macromolecular nucleating agent, thereby meeting the particle size requirements of high-purity calcium carbonate in the fields of optical glass and high-purity calcium salt preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the following detailed description of the preferred embodiment.The drawings are only for the purpose of illustrating the preferred embodiments and are not to be construed as limiting the invention.

[0027] Figure 1 This is a particle size distribution diagram of calcium carbonate particles prepared in Example 1;

[0028] Figure 2 This is a particle size distribution diagram of calcium carbonate particles prepared in Example 2;

[0029] Figure 3 This is a particle size distribution diagram of calcium carbonate particles prepared in Example 3;

[0030] Figure 4 This is a particle size distribution diagram of calcium carbonate particles prepared in Example 4;

[0031] Figure 5 This is the particle size distribution diagram of the calcium carbonate particles prepared in Example 5. DETAILED DESCRIPTION

[0032] In order to fully understand the purpose, features and effects of the present invention, the present invention is described in detail through the following specific embodiments. Except for the following contents, the process method of the present invention adopts conventional methods or devices in the art. Unless otherwise specified, the following terms have the meanings commonly understood by those skilled in the art.

[0033] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0034] Specifically, the method for synthesizing large-particle-size high-purity precipitated calcium carbonate provided by the present invention comprises the following steps:

[0035] Prepare calcium salt solution

[0036] The water-soluble calcium salt is dissolved in pure water to obtain a calcium salt solution with a concentration of 0.4 to 4.0 mol / L.

[0037] In some preferred embodiments, a pH regulator is selectively added to the calcium salt solution to adjust the pH to 3-11.

[0038] Optionally, the concentration of the calcium salt solution is 0.4mol / L, 0.5mol / L, 0.6mol / L, 0.7mol / L, 0.8mol / L, 0.9mol / L, 1.0mol / L, 1.1mol / L, 1.2mol / L, 1.3mol / L, 1.4mol / L, 1.5mol / L, 1.6mol / L, 1.7mol / L, 1.8mol / L, 1.9mol / L, 2.0mol / L, 2.1mol / L, 2.2mol / L, 2.3mol / L, 2.4mol / L, 2.5mol / L, 2.6mol / L, 2.7mol / L, 2.8mol / L, 2.9mol / L, 3.0mol / L, 3.1mol / L, 3.2mol / L, 3.3mol / L, 3.4mol / L, 3.5mol / L, 3.6mol / L, 3.7mol / L, 3.8mol / L, 3.9mol / L or 4.0mol / L.

[0039] In some preferred embodiments, the concentration of the calcium salt solution is 1.5 to 2.5 mol / L.

[0040] Optionally, the pH of the calcium salt solution is 3, 4, 5, 6, 7, 8, 9, 10 or 11.

[0041] In some preferred embodiments, the pH of the calcium salt solution is 5-10.

[0042] In some preferred embodiments, the water-soluble calcium salt includes one or more of calcium chloride and calcium nitrate.

[0043] In some preferred embodiments, the pH regulator is one or more of hydrochloric acid, nitric acid, ammonia water, and calcium hydroxide.

[0044] Prepare carbonate solution

[0045] A water-soluble carbonate is dissolved in pure water to obtain a carbonate solution with a concentration of 0.8 to 3.2 mol / L.

[0046] Optionally, the concentration of the carbonate solution is 0.8mol / L, 0.9mol / L, 1.0mol / L, 1.1mol / L, 1.2mol / L, 1.3mol / L, 1.4mol / L, 1.5mol / L, 1.6mol / L, 1.7mol / L, 1.8mol / L, 1.9mol / L, 2.0mol / L, 2.1mol / L, 2.2mol / L, 2.3mol / L, 2.4mol / L, 2.5mol / L, 2.6mol / L, 2.7mol / L, 2.8mol / L, 2.9mol / L, 3.0mol / L, 3.1mol / L or 3.2mol / L.

[0047] In some preferred embodiments, the concentration of the carbonate solution is 1.5 to 2.5 mol / L.

[0048] In some preferred embodiments, the water-soluble carbonate includes one or more of ammonium carbonate and sodium carbonate.

[0049] Preparation of calcium carbonate

[0050] Add 0.3~3m 3 pure water, start stirring, the stirring rate is 24-85rpm; after heating the calcium salt solution to 10-70°C, the carbonate solution is heated to 10-30°C, and then continuously injected into the synthesis kettle under stirring to react to obtain calcium carbonate slurry.

[0051] Wherein, the flow rate of the calcium salt solution is 0.16~4.0m 3 / h; the flow rate of the carbonate solution is 0.08~5m 3 / h; the reaction temperature is 10-55°C.

[0052] Optionally, the amount of pure water added to the synthesis reactor is 0.3m 3 、0.4m 3 、0.5m 3 、0.6m 3 、0.7m 3 、0.8m 3 、0.9m 3 , 1.0m 3 、1.1m 3 , 1.2m 3 、1.3m 3 、1.4m 3 , 1.5m 3 、1.6m 3 、1.7m 3 、1.8m 3 、1.9m3 , 2.0m 3 , 2.1m 3 , 2.2m 3 、2.3m 3 、2.4m 3 , 2.5m 3 、2.6m 3 、2.7m 3 、2.8m 3 、2.9m 3 or 3.0m 3 .

[0053] In some preferred embodiments, the amount of pure water added to the synthesis reactor is 1.0 to 2.0 m 3 .

[0054] Optionally, the stirring rate of the synthesis reactor is 24 rpm, 30 rpm, 35 rpm, 40 rpm, 45 rpm, 50 rpm, 55 rpm, 60 rpm, 65 rpm, 70 rpm, 75 rpm, 80 rpm or 85 rpm.

[0055] In some preferred embodiments, the stirring rate of the synthesis reactor is 40-65 rpm.

[0056] Optionally, the temperature of the calcium salt solution before the reaction is 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C or 70°C.

[0057] In some preferred embodiments, the temperature of the calcium salt solution before the reaction is 30-50°C.

[0058] Optionally, the temperature of the carbonate solution before the reaction is 10°C, 12°C, 14°C, 16°C, 18°C, 20°C, 22°C, 24°C, 26°C, 28°C or 30°C.

[0059] In some preferred embodiments, the temperature of the carbonate solution before the reaction is 16-24°C.

[0060] Optionally, the flow rate of the calcium salt solution is 0.16m 3 / h、0.4m 3 / h、0.8m 3 / h、1.2m 3 / h、1.6m 3 / h, 2.0m 3 / h, 2.5m 3 / h, 2.8m 3 / h, 3.2m 3 / h

[0061] In some preferred embodiments, the flow rate of the calcium salt solution is 1.2 to 2.0 m 3 / h.

[0062] Optionally, the flow rate of the carbonate solution is 0.08m 3 / h、0.2m 3 / h、1.0m 3 / h、1.5m 3 / h、2.0m 3 / h, 2.5m 3 / h, 3.0m 3 / h, 3.5m 3 / h, 4.0m 3 / h

[0063] In some preferred embodiments, the flow rate of the carbonate solution is 1.5 to 3.0 m 3 / h.

[0064] Optionally, the temperature at which the carbonate solution reacts with the calcium salt solution is 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C or 55°C.

[0065] In some preferred embodiments, the temperature at which the carbonate solution reacts with the calcium salt solution is 25-40°C.

[0066] Purification of calcium carbonate

[0067] The calcium carbonate slurry is filtered, washed and dried to obtain large-particle-size high-purity precipitated calcium carbonate.

[0068] In some preferred embodiments, the washing is performed in a washing tank using pure water.

[0069] In some preferred embodiments, the drying is performed in an oven at a temperature of 110-400°C.

[0070] The present invention does not need to add other nucleating agents. Only by adjusting the concentration, pH value and temperature of calcium salt and carbonate, controlling the mixed reaction flow rate, stirring rate and reaction temperature, large-particle / super-large-particle high-purity calcium carbonate with a particle size (D50) of 20 to 115 μm can be obtained.

[0071] The calcium carbonate prepared according to the method of the present invention has high purity, low impurity content, adjustable particle size, and can produce ultra-large particle size calcium carbonate particles with a particle size (D50) exceeding 60 μm.

[0072] Example

[0073] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions. The raw materials used in the following examples are all conventionally purchased.

[0074] Example 1

[0075] 1. Use pure water to prepare calcium chloride aqueous solution with a concentration of 4.0 mol / L. Add a small amount of calcium hydroxide to adjust the pH of the solution to 11.

[0076] 2. Use pure water to prepare an aqueous solution of ammonium carbonate with a concentration of 3.2 mol / L.

[0077] 3. Add 0.3m3 of bottom water (pure water) into the synthesis kettle. 3 , start stirring, and the stirring speed of the synthesis reactor is 85 rpm.

[0078] 4. Control the flow rate of calcium chloride aqueous solution into the synthesis kettle to 3.2m 3 / h, temperature 70℃; ammonium carbonate solution is injected into the synthesis reactor at a flow rate of 4m 3 / h, temperature 30℃; synthesis reactor reaction temperature 55℃.

[0079] 5. After the synthesis reaction is completed, the filter cake is filtered and washed with pure water, and the weight ratio of washing water to calcium carbonate is 6:1. After washing, the calcium carbonate filter cake is transferred to an oven and dried at 400°C for 3 hours to obtain calcium carbonate particles.

[0080] The calcium carbonate particles prepared in Example 1 were subjected to particle size analysis, and the particle size (D50) was 22 μm. The particle size distribution results are shown in Figure 1 .

[0081] Example 2

[0082] 1. Use pure water to prepare calcium nitrate aqueous solution with a concentration of 0.4 mol / L. Add a small amount of nitric acid to adjust the pH of the solution to 3.

[0083] 2. Use pure water to prepare a sodium carbonate aqueous solution with a concentration of 0.8 mol / L.

[0084] 3. Add 3 ml of bottom water (pure water) into the synthesis kettle. 3 , start stirring, and the stirring speed of the synthesis reactor is 24 rpm.

[0085] 4. Control the flow rate of calcium nitrate aqueous solution into the synthesis kettle to 0.16m 3 / h, temperature 10℃; sodium carbonate solution is injected into the synthesis reactor at a flow rate of 0.08m 3 / h, temperature 10℃; synthesis reactor reaction temperature 10℃.

[0086] 5. After the synthesis reaction is completed, the filter cake is filtered and washed with pure water, and the weight ratio of washing water to calcium carbonate is 6:1. After washing, the calcium carbonate filter cake is transferred to an oven and dried at 400°C for 3 hours to obtain calcium carbonate particles.

[0087] The calcium carbonate particles prepared in Example 2 were subjected to particle size analysis, and the particle size (D50) was 114 μm. The particle size distribution results are shown in Figure 2 .

[0088] Example 3

[0089] 1. Use pure water to prepare calcium nitrate aqueous solution, where the concentration of calcium nitrate aqueous solution is 2.5 mol / L, and add a small amount of ammonia water to adjust the solution pH to 7.

[0090] 2. Use pure water to prepare an ammonium carbonate aqueous solution with a concentration of 2.0 mol / L.

[0091] 3. Add 1.6 ml of bottom water (pure water) into the synthesis kettle. 3 , start stirring, and the stirring speed of the synthesis reactor is 55 rpm.

[0092] 4. Control the flow rate of calcium nitrate aqueous solution into the synthesis kettle at 2m 3 / h, temperature 35℃; ammonium carbonate solution is injected into the synthesis reactor at a flow rate of 2.5m 3 / h, temperature 20℃; synthesis reactor reaction temperature 30℃.

[0093] 5. After the synthesis reaction is completed, the filter cake is filtered and washed with pure water, and the weight ratio of washing water to calcium carbonate is 6:1. After washing, the calcium carbonate filter cake is transferred to an oven and dried at 110°C for 12 hours to obtain calcium carbonate particles with a particle size of 66 μm.

[0094] The particle size analysis of the calcium carbonate particles prepared in Example 3 showed that the particle size (D50) was 66 μm. The particle size distribution results are shown in Figure 3 .

[0095] Example 4

[0096] 1. Use pure water to prepare calcium chloride aqueous solution, where the solution concentration is 0.8 mol / L, and add a small amount of hydrochloric acid to adjust the solution pH to 4.5.

[0097] 2. Use pure water to prepare an ammonium carbonate aqueous solution with a concentration of 1.6 mol / L.

[0098] 3. Add 2.5 ml of bottom water (pure water) into the synthesis kettle. 3 , start stirring, and the stirring speed of the synthesis reactor is 30 rpm.

[0099] 4. Control the flow rate of calcium chloride aqueous solution into the synthesis kettle to 0.4m 3 / h, temperature 20℃; ammonium carbonate solution is injected into the synthesis reactor at a flow rate of 0.2m 3 / h, temperature 20℃; synthesis reactor reaction temperature 20℃.

[0100] 5. After the synthesis reaction is completed, the filter cake is filtered and washed with pure water, and the weight ratio of washing water to calcium carbonate is 6:1. After washing, the calcium carbonate filter cake is transferred to an oven and dried at 180°C for 8 hours to obtain calcium carbonate particles with a particle size of 104 μm.

[0101] The calcium carbonate particles prepared in Example 4 were subjected to particle size analysis, and the particle size (D50) was 104 μm. The particle size distribution results are shown in Figure 4 .

[0102] Example 5

[0103] 1. Use pure water to prepare calcium nitrate aqueous solution, wherein the concentration of calcium nitrate aqueous solution is 1.8 mol / L, and no acid-base regulator is needed. At this time, the pH of the calcium nitrate solution is 5.5.

[0104] 2. Use pure water to prepare a 2.0 mol / L sodium carbonate aqueous solution.

[0105] 3. Add 1.5 ml of bottom water (pure water) into the synthesis kettle. 3 , start stirring, and the stirring speed of the synthesis reactor is 40 rpm.

[0106] 4. Control the flow rate of calcium nitrate aqueous solution into the synthesis kettle to 1.0m 3 / h, temperature 30℃; sodium carbonate solution is injected into the synthesis reactor at a flow rate of 0.9m 3 / h, temperature 20℃; synthesis reactor reaction temperature 26℃.

[0107] 5. After the synthesis reaction is completed, the filter cake is filtered and washed with pure water, and the weight ratio of washing water to calcium carbonate is 6:1. After washing, the calcium carbonate filter cake is transferred to an oven and dried at 220°C for 8 hours to obtain calcium carbonate particles with a particle size of 91 μm.

[0108] The calcium carbonate particles prepared in Example 5 were subjected to particle size analysis, and the particle size (D50) was 91 μm. The particle size distribution results are shown in Figure 5 .

[0109] The present invention has been disclosed above with preferred embodiments, but those skilled in the art should understand that these embodiments are only used to describe the present invention and should not be understood as limiting the scope of the present invention. It should be noted that all changes and substitutions equivalent to these embodiments should be deemed to be included in the scope of the claims of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined in the claims.

Claims

1. A method for synthesizing large-particle-size high-purity precipitated calcium carbonate, characterized in that: include: (1) dissolving a water-soluble calcium salt in pure water to obtain a calcium salt solution with a concentration of 0.4 to 4.0 mol / L; (2) dissolving a water-soluble carbonate in pure water to obtain a carbonate solution having a concentration of 0.8 to 3.2 mol / L; (3) Add 0.3-3 m 3 Pure water, start stirring, stirring speed is 24~85rpm; (4) heating the calcium salt solution to 10-70° C. and the carbonate solution to 10-30° C., and then continuously injecting the solution into the synthesis reactor under stirring to react and obtain calcium carbonate slurry; Wherein, the flow rate of the calcium salt solution is 0.16~4.0m 3 / h; the flow rate of the carbonate solution is 0.08~5.0m 3 / h; the stirring rate is 24-85rpm; the reaction temperature is 10-55°C; (5) The calcium carbonate slurry is filtered, washed and dried to obtain large-particle-size high-purity precipitated calcium carbonate.

2. The synthesis method according to claim 1, characterized in that The water-soluble calcium salt includes one or more of calcium chloride and calcium nitrate.

3. The synthesis method according to claim 1, characterized in that The water-soluble carbonate includes one or more of ammonium carbonate and sodium carbonate.

4. The synthesis method according to claim 1, characterized in that The pH regulator is one or more of hydrochloric acid, nitric acid, ammonia water, and calcium hydroxide.

5. The synthesis method according to claim 1, characterized in that The concentration of the calcium salt solution is 1.5-2.5 mol / L and the pH is 3-11; the concentration of the carbonate solution is 1.5-2.5 mol / L.

6. The synthesis method according to claim 1, characterized in that The amount of pure water added to the synthesis kettle is 1.0-2.0 m 3 , the stirring rate is 40-65rpm.

7. The synthesis method according to claim 1, characterized in that In step (4), the heating temperature of the calcium salt solution is 30-50°C; the heating temperature of the carbonate solution is 16-24°C.

8. The synthesis method according to claim 1, characterized in that In step (4), the flow rate of the calcium salt solution is 1.2 to 2.0 m 3 / h; the flow rate of the carbonate solution is 1.5 to 3.0m 3 / h; the stirring rate is 40-65rpm; the reaction temperature is 25-40°C.

9. A large-particle high-purity precipitated calcium carbonate, characterized in that: The compound is prepared by the synthesis method according to any one of claims 1 to 8.

10. The large-particle high-purity precipitated calcium carbonate according to claim 9, characterized in that: The particle size of the precipitated calcium carbonate is 20 to 115 μm.

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