A kind of rod-shaped calcium carbonate and its preparation method and application

Abstract

The present invention provides a rod-shaped calcium carbonate and a preparation method and application thereof. The preparation method comprises the following steps: (1) dissolving a calcium source in deionized water and then adding an acidic solution to mix, thereby obtaining a first mixed solution; (2) adjusting the temperature of the first mixed solution in step (1), adding a weak alkaline solution to adjust the pH, thereby obtaining a second mixed solution; (3) introducing carbon dioxide into the second mixed solution in step (2) to perform a carbonization reaction until the pH of the reaction solution is 7.0 to 7.5, and then aging, filtering, washing and drying to obtain the rod-shaped calcium carbonate. The calcium carbonate prepared by the present invention has a smooth surface, a large aspect ratio, and contains fewer impurities. The preparation process is simple, and it is easy to realize industrialization, and has good application prospects.

Description

Technical Field

[0001] The invention relates to the field of chemical fillers, and in particular to rod-shaped calcium carbonate and a preparation method and application thereof. Background Art

[0002] Calcium carbonate is widely used in industries such as plastics, papermaking, coatings, inks, and daily chemicals. Calcium carbonate is generally used as a filling material, which has the advantages of being non-toxic, low cost, and rich in raw materials. Calcium carbonate is classified according to particle size: micron, submicron, and nanometer, respectively. At the same time, calcium carbonate has a variety of morphologies, such as cubes, spindles, needles, and spheres. Due to the differences in the morphology and size of calcium carbonate, different functionalities are reflected in the application. Whisker-shaped calcium carbonate, as a reinforcing material, can significantly enhance the toughness of the body like fibers, while enhancing the plasticity of the matrix; by changing the particle size, the rheological properties of the material can be improved during the processing. At present, spindle-shaped calcium carbonate is most widely used in the papermaking industry, which can improve the surface gloss of paper. The use of needle-shaped calcium carbonate fillers is conducive to enhancing the overall toughness of the material, improving strength and tearing properties. my country is a country with abundant calcium carbonate resources, but there are still problems in product development such as low product added value, low technical content, single variety, and serious repetitiveness. Most high-end calcium carbonate products still rely on imports, and are in a relatively backward position in the world's calcium carbonate industry.

[0003] At present, most calcium carbonate production processes use the CO2 carbonization method of passing CO2 into a Ca(OH)2 suspension. The calcium carbonate crystal form is regulated by adding a large amount of crystal control agents such as MgCl2 to obtain different morphologies. However, this method is costly and is more likely to contain Mg impurities, making it unsuitable for large-scale production.

[0004] CN 110844930A discloses a method for preparing hollow rod-shaped calcium carbonate, wherein calcium oxide is weighed and dissolved in water to obtain calcium hydroxide slurry, sodium D-gluconate is added to the calcium hydroxide slurry, and then carbon dioxide gas is introduced to obtain product slurry, and the product slurry is filtered and washed to separate and obtain powdered hollow rod-shaped calcium carbonate. However, the process control in the preparation process needs to be further improved, and the particle size of the product needs to be further improved.

[0005] CN 110451545 A discloses a method for preparing rod-shaped calcium carbonate for PE breathable membrane, wherein different morphologies can be obtained by adjusting the carbon dioxide into the CO2 carbonization method of Ca(OH)2 suspension and adding tetrasodium pyrophosphate to realize the carbonization reaction. However, the method has the problem of high cost and is not suitable for large-scale production.

[0006] Therefore, how to prepare a low-cost, large-scale, high-performance rod-shaped sodium carbonate is an important research direction in this field. Summary of the invention

[0007] The object of the present invention is to provide a rod-shaped calcium carbonate and a preparation method and application thereof.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] One of the objects of the present invention is to provide a method for preparing rod-shaped calcium carbonate, the preparation method comprising the following steps:

[0010] (1) dissolving a calcium source in deionized water and then adding an acidic solution to mix the mixture to obtain a first mixed solution;

[0011] (2) adjusting the temperature of the first mixed solution in step (1), and then adding a weak alkaline solution to adjust the pH to obtain a second mixed solution;

[0012] (3) introducing carbon dioxide into the second mixed solution of step (2) to carry out carbonization reaction until the pH value of the reaction solution is 7.0 to 7.5, aging, filtering, washing and drying to obtain the rod-shaped calcium carbonate.

[0013] In the present invention, a certain amount of calcium source is dissolved in water, and after adding acid and fully mixing, calcium ion solutions of different concentrations are obtained. After adjusting the temperature of the solution and then adjusting the pH, carbon dioxide gas is introduced to carry out a carbonization reaction. The whole process is controlled by adjusting the product of different calcium ion and carbonate ion concentrations in the solution to obtain rod-shaped calcium carbonate. When the pH value of the reaction solution drops to 7.0-7.5, the introduction of carbon dioxide is stopped to obtain calcium carbonate slurry. The calcium carbonate slurry is filtered, dried and crushed to obtain rod-shaped calcium carbonate powder.

[0014] As a preferred technical solution of the present invention, the calcium source in step (1) includes calcium hydroxide.

[0015] Preferably, the acidic solution in step (1) is any one of hydrochloric acid, sulfuric acid, nitric acid or an organic acid, or a combination of at least two thereof, wherein typical but non-limiting examples of the combination include: a combination of hydrochloric acid and sulfuric acid, a combination of sulfuric acid and nitric acid, a combination of nitric acid and acetic acid, or a combination of acetic acid and an organic acid, etc.

[0016] Preferably, the organic acid comprises acetic acid.

[0017] Preferably, the H of the acidic solution + The concentration is 17-18 mol / L, wherein the concentration can be 17 mol / L, 17.1 mol / L, 17.2 mol / L, 17.3 mol / L, 17.4 mol / L, 17.5 mol / L, 17.6 mol / L, 17.7 mol / L, 17.8 mol / L, 17.9 mol / L or 18 mol / L, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] As a preferred technical solution of the present invention, the mass ratio of the calcium source and deionized water in step (1) is (0.007-0.02):1, wherein the mass ratio can be 0.007:1, 0.008:1, 0.009:1, 0.01:1, 0.011:1, 0.012:1, 0.013:1, 0.014:1, 0.015:1, 0.016:1, 0.017:1, 0.018:1, 0.019:1 or 0.02:1, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] Preferably, the mass ratio of the calcium source and the acidic solution in step (1) is (0.5-0.7):1, wherein the mass ratio can be 0.5:1, 0.52:1, 0.54:1, 0.56:1, 0.58:1, 0.60:1, 0.62:1, 0.64:1, 0.66:1, 0.68:1 or 0.7:1, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] Preferably, the mass concentration of the calcium source in step (1) is 0.1-3%, wherein the mass concentration can be 0.1%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5% or 3%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] As a preferred technical solution of the present invention, the mixing temperature in step (1) is 25-30°C, wherein the temperature can be 25°C, 26°C, 27°C, 28°C, 29°C or 30°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0022] Preferably, the mixing time in step (1) is 5 to 20 min, wherein the time can be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min or 20 min, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] As a preferred technical solution of the present invention, the weak alkaline solution in step (2) includes aqueous ammonia.

[0024] Preferably, the volume ratio of the weak base and the first mixed solution is (0.02-0.03):1, wherein the volume ratio can be 0.021:1, 0.022:1, 0.023:1, 0.024:1, 0.025:1, 0.026:1, 0.027:1, 0.028:1, 0.029:1 or 0.03:1, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] As a preferred technical solution of the present invention, the temperature adjustment method in step (2) includes water bath heating.

[0026] Preferably, the temperature in step (2) is adjusted to control the temperature at 20-90°C, wherein the temperature can be 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C or 90°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] Preferably, the pH in step (2) is 9.0-11.0, wherein the pH can be 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10.0, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9 or 11.0, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] As a preferred technical solution of the present invention, the volume concentration of carbon dioxide in step (3) is 20-100%, wherein the concentration can be 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] Preferably, in step (3), the gas flow rate of the carbon dioxide introduced into the second mixed liquid is 5 to 50 ml / min, wherein the gas flow rate can be 5 ml / min, 10 ml / min, 15 ml / min, 20 ml / min, 25 ml / min, 30 ml / min, 35 ml / min, 40 ml / min, 45 ml / min or 50 ml / min, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0030] Preferably, the carbon dioxide in step (3) and the initial CO3 in the second mixed liquid 2- / Ca 2+The molar concentration ratio is 0.002 to 0.03, wherein the ratio may be 0.002, 0.005, 0.01, 0.015, 0.02, 0.025 or 0.03, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] As a preferred technical solution of the present invention, the temperature of the carbonization reaction in step (3) is 70-90°C, wherein the temperature can be 70°C, 72°C, 74°C, 76°C, 78°C, 80°C, 82°C, 84°C, 86°C, 88°C or 90°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] Preferably, the time of the carbonization reaction in step (3) is 100 to 180 min, wherein the time may be 100 min, 110 min, 120 min, 130 min, 140 min, 150 min, 160 min, 170 min or 180 min, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0033] A second object of the present invention is to provide a rod-shaped calcium carbonate, wherein the rod-shaped calcium carbonate is prepared by the preparation method described in one of the objects.

[0034] The particle size of the rod-shaped calcium carbonate is less than 1 μm, wherein the particle size can be 0.01 μm, 0.05 μm, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm or 0.9 μm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] The aspect ratio of the rod-shaped calcium carbonate is 10 to 25, wherein the aspect ratio can be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] The third object of the present invention is to provide an application of the rod-shaped calcium carbonate as described in the second object, characterized in that the rod-shaped calcium carbonate is used in the field of chemical fillers.

[0037] The field of chemical fillers in the present invention includes papermaking, rubber, dyes and other chemical filler fields.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The calcium carbonate prepared by the invention has a smooth surface, a large aspect ratio, and contains fewer impurities. The preparation process is simple, and industrialization is easy to achieve, thereby having good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 1 is a microstructure diagram of rod-shaped calcium carbonate in Example 1 of the present invention.

[0041] Figure 2 1 is a microstructure diagram of rod-shaped calcium carbonate in Example 4 of the present invention.

[0042] Figure 3 It is a microstructure diagram of rod-shaped calcium carbonate in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0043] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0044] Example 1

[0045] The present embodiment provides a method for preparing rod-shaped calcium carbonate, comprising the following steps:

[0046] (1) dissolving 2.93 g of calcium hydroxide in 400 ml of deionized water, and then adding glacial acetic acid to mix the mixture so that the concentration of calcium ions is 0.1 mol / L, thereby obtaining a first mixed solution;

[0047] (2) heating the first mixed solution in step (1) to 90° C. in a water bath, and then adding ammonia water to adjust the pH to 10.0 to obtain a second mixed solution;

[0048] (3) Add 10 ml / min of carbon dioxide (CO3) into the second mixed solution of step (2). 2- / Ca 2+ The molar concentration ratio is 0.003) and carbonization reaction is carried out until the pH of the reaction solution reaches 7.2, and then aging, filtering, washing and drying are performed to obtain rod-shaped calcium carbonate.

[0049] The microstructure of the rod-shaped calcium carbonate in this embodiment is shown in FIG. Figure 1 shown.

[0050] Example 2

[0051] The present embodiment provides a method for preparing rod-shaped calcium carbonate, comprising the following steps:

[0052] (1) dissolving 2.93 g of calcium hydroxide in 400 ml of deionized water, and then adding glacial acetic acid to mix the mixture so that the concentration of calcium ions is 0.1 mol / L, thereby obtaining a first mixed solution;

[0053] (2) heating the first mixed solution in step (1) to 55° C. in a water bath, and then adding ammonia water to adjust the pH to 9.0 to obtain a second mixed solution;

[0054] (3) Add 5 ml / min of carbon dioxide (CO3) into the second mixed solution of step (2). 2- / Ca 2+ The molar concentration ratio is 0.002) and carbonization reaction is carried out until the pH of the reaction solution reaches 7.0, and then aging, filtering, washing and drying are performed to obtain rod-shaped calcium carbonate.

[0055] Example 3

[0056] The present embodiment provides a method for preparing rod-shaped calcium carbonate, comprising the following steps:

[0057] (1) dissolving 2.93 g of calcium hydroxide in 400 ml of deionized water, and then adding glacial acetic acid to mix the mixture so that the concentration of calcium ions is 0.1 mol / L, thereby obtaining a first mixed solution;

[0058] (2) heating the first mixed solution in step (1) to 20° C. in a water bath, and then adding ammonia water to adjust the pH to 11.0 to obtain a second mixed solution;

[0059] (3) Add 50 ml / min of carbon dioxide (CO3) into the second mixed solution of step (2). 2- / Ca 2+ The molar concentration ratio is 0.03) and carbonization reaction is carried out until the pH of the reaction solution reaches 7.5, and then aging, filtering, washing and drying are performed to obtain rod-shaped calcium carbonate.

[0060] Example 4

[0061] The present embodiment provides a method for preparing rod-shaped calcium carbonate, comprising the following steps:

[0062] (1) dissolving 1.86 g of calcium hydroxide in 400 ml of deionized water, and then adding glacial acetic acid and mixing, so that the concentration of calcium ions is 0.05 mol / L, to obtain a first mixed solution;

[0063] (2) heating the first mixed solution in step (1) to 90° C. in a water bath, and then adding ammonia water to adjust the pH to 10.0 to obtain a second mixed solution;

[0064] (3) Add 50 ml / min of carbon dioxide (CO3) into the second mixed solution of step (2). 2- / Ca 2+ The molar concentration ratio is 0.006) and carbonization reaction is carried out until the pH of the reaction solution reaches 7.2, and then aging, filtering, washing and drying are performed to obtain rod-shaped calcium carbonate.

[0065] The microstructure of the rod-shaped calcium carbonate in this embodiment is shown in FIG. Figure 2 shown.

[0066] Example 5

[0067] In this embodiment, except that the step (2) of adding ammonia water to adjust the pH to 10.0 is replaced by adding ammonia water to adjust the pH to 8.5, other conditions are the same as those in embodiment 1.

[0068] Example 6

[0069] In this embodiment, except that the step (2) of adding ammonia water to adjust the pH to 10.0 is replaced by adding ammonia water to adjust the pH to 11.5, other conditions are the same as those in embodiment 1.

[0070] Example 7

[0071] In this embodiment, in addition to step (3), CO3 2- / Ca 2+ Except that the ratio of 0.003 is replaced by 0.001, other conditions are the same as those in Example 1.

[0072] Example 8

[0073] In this embodiment, in addition to step (3), CO3 2- / Ca 2+ Except that the ratio of 0.003 is replaced by 0.06, other conditions are the same as those in Example 1.

[0074] Comparative Example 1

[0075] This comparative example provides a method for preparing rod-shaped calcium carbonate, comprising the following steps:

[0076] (1) dissolving 0.879 g of calcium hydroxide in 400 ml of deionized water and mixing the mixture so that the concentration of calcium ions is 0.01 mol / L to obtain a first mixed solution;

[0077] (2) heating the first mixed solution in step (1) to 90° C. in a water bath, and then adding ammonia water to adjust the pH to 10.0 to obtain a second mixed solution;

[0078] (3) Add 10 ml / min of carbon dioxide (CO3) into the second mixed solution of step (2). 2- / Ca 2+ The molar ratio of the reaction mixture is 0.03) and carbonization reaction is carried out until the pH of the reaction solution reaches 7.2, followed by aging, filtration, washing and drying to obtain rod-shaped calcium carbonate.

[0079] The microstructure of the rod-shaped calcium carbonate in this comparative example is shown in FIG. Figure 3 shown.

[0080] The rod-shaped calcium carbonate in Examples 1-8 and Comparative Example 1 was tested for sample particle size, aspect ratio and impurities. The test results are shown in Table 1.

[0081] Among them, the particle size of the samples was tested by scanning electron microscopy (SEM);

[0082] The aspect ratio of the samples was tested using a scanning electron microscope (SEM);

[0083] The impurity rate of the samples was tested using an X-ray diffractometer and an X-ray fluorescence spectrometer.

[0084] Table 1

[0085]

[0086]

[0087] It can be seen from the above table that the rod-shaped calcium carbonate in Examples 1-4 has a lower particle size, a larger aspect ratio and a lower impurity rate.

[0088] Compared with Example 1, in Examples 5-6, too high or too low pH of the solution during the reaction process will also have an adverse effect on the aspect ratio of the rod-shaped calcium carbonate.

[0089] Compared with Example 1, when CO3 2- / Ca 2+ When the ratio of CO3 increases within the range, the aspect ratio of the obtained rod-shaped calcium carbonate gradually decreases, and the purity of the rod-shaped calcium carbonate also decreases. 2- / Ca 2+ When the ratio exceeds the range, rod-shaped calcium carbonate is difficult to generate, and most of them are cubic calcium carbonate with an extremely low aspect ratio.

[0090] In comparative example 1, glacial acetic acid was not added in step (1), and CO3 2- / Ca 2+ As the proportion increases, the impurity rate increases.

[0091] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing rod-shaped calcium carbonate, characterized in that: The preparation method comprises the following steps: (1) dissolving a calcium source in deionized water and then adding an acidic solution to mix the mixture to obtain a first mixed solution; The calcium source includes calcium hydroxide; (2) adjusting the temperature of the first mixed solution in step (1), and then adding a weak alkaline solution to adjust the pH to 9.0-11.0 to obtain a second mixed solution; (3) introducing carbon dioxide into the second mixed solution of step (2) to carry out a carbonization reaction until the pH of the reaction solution is 7.0 to 7.5, and then aging, filtering, washing and drying to obtain the rod-shaped calcium carbonate; The initial CO3 in the carbon dioxide and the second mixed liquid 2- / Ca 2+ The molar concentration ratio is 0.002 to 0.

03.

2. The preparation method according to claim 1, characterized in that: The acidic solution in step (1) is any one of hydrochloric acid, sulfuric acid, nitric acid or an organic acid, or a combination of at least two thereof.

3. The preparation method according to claim 2, characterized in that: The organic acid includes acetic acid.

4. The preparation method according to claim 1, characterized in that: The acidic solution H + The concentration is 17~18mol / L.

5. The preparation method according to claim 1, characterized in that: The mass ratio of the calcium source to deionized water in step (1) is (0.007-0.02):

1.

6. The preparation method according to claim 1, characterized in that: The mass ratio of the calcium source to the acidic solution in step (1) is (0.5-0.7):

1.

7. The preparation method according to claim 1, characterized in that: The mass concentration of the calcium source in step (1) is 0.1-3%.

8. The preparation method according to claim 1, characterized in that: The mixing temperature in step (1) is 25-30°C.

9. The preparation method according to claim 1, characterized in that: The mixing time in step (1) is 5 to 20 minutes.

10. The preparation method according to claim 1, characterized in that: The weak alkaline solution in step (2) includes aqueous ammonia.

11. The preparation method according to claim 1, characterized in that: The volume ratio of the weak alkaline solution to the first mixed solution is (0.02-0.03):

1.

12. The preparation method according to claim 1, characterized in that: The temperature adjustment method in step (2) includes water bath heating.

13. The preparation method according to claim 1, characterized in that: The temperature in step (2) is adjusted to control the temperature at 20-90°C.

14. The preparation method according to claim 1, characterized in that: The volume concentration of the carbon dioxide in step (3) is 20 to 100%.

15. The preparation method according to claim 1, characterized in that: In step (3), the gas flow rate of the carbon dioxide introduced into the second mixed liquid is 5 to 50 ml / min.

16. The preparation method according to claim 1, characterized in that: The temperature of the carbonization reaction in step (3) is 70-90°C.

17. The preparation method according to claim 1, characterized in that: The carbonization reaction time in step (3) is 100 to 180 minutes.

18. A rod-shaped calcium carbonate, characterized in that: The rod-shaped calcium carbonate is prepared by the preparation method described in any one of claims 1-17.

19. The rod-shaped calcium carbonate according to claim 18, characterized in that: The particle size of the rod-shaped calcium carbonate is less than 1 μm.

20. The rod-shaped calcium carbonate according to claim 18, characterized in that: The aspect ratio of the rod-shaped calcium carbonate is 10-25.

21. A use of the rod-shaped calcium carbonate as claimed in claim 18, characterized in that: The rod-shaped calcium carbonate is used in the field of chemical fillers.

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