Process for preparing nano calcium carbonate based on carbonization method

Abstract

The invention discloses a process for preparing nano calcium carbonate based on a carbonization method, which comprises the following steps: S1, mixing calcium hydroxide emulsion with hydrogen peroxide, and then spraying into a reactor in a mist form; introducing and adding a mixed gas of carbon dioxide and nitrogen into the reactor under high pressure to form a nanoscale three-dimensional airflow net, mixing the nanoscale three-dimensional airflow net with the calcium hydroxide emulsion, carrying out carbonization reaction, and then carrying out high-strength shearing to obtain calcium carbonate slurry; s2, firstly adding fatty acid into the calcium carbonate slurry, uniformly mixing, then adding magnesium sulfate, and uniformly mixing to obtain modified calcium carbonate; s3, the modified calcium carbonate is subjected to centrifugal separation, drying and smashing, and the nano calcium carbonate powder is obtained. The method has the characteristics of large gas-liquid contact area, short carbonization time, uniform and stable finished product and good dispersity.

Description

Technical Field

[0001] This invention relates to a production process for nano-calcium carbonate, and more particularly to a process for preparing nano-calcium carbonate based on the carbonation method. Background Technology

[0002] Nano-calcium carbonate is an ultrafine calcium carbonate powder with a stable particle size in the range of 1-100 nanometers. It possesses characteristics such as small size effect, high specific surface area, and high surface activity, which can significantly improve the mechanical properties of materials. Currently, methods for preparing nano-calcium carbonate include carbonation, metathesis, emulsion, and electrochemical methods. Among these, carbonation is the most commonly used method. Its process flow is as follows: high-quality limestone is calcined to produce quicklime (CaO) and kiln gas (CO2). The quicklime is then treated and reacted with water in a lime-slaked tank to produce lime milk (Ca(OH)2). After refining, the lime milk is reacted with CO2 in a carbonation device. Through crystal form regulators and process control, a nano-calcium carbonate suspension is obtained. Surface modifiers (such as coupling agents) can be added to the prepared nano-calcium carbonate suspension for surface activation modification. Then, through processes such as filtration, drying, pulverization, grading, and packaging, the nano-calcium carbonate product is obtained.

[0003] Carbonation reactions include intermittent bubbling carbonation and continuous spray carbonation. Intermittent bubbling carbonation involves cooling lime slurry (5-8 Baume degree) to below 25°C using a chiller, pumping it into a carbonation tower, and directly introducing carbon dioxide gas from the bottom of the tower to bubble and carry out the carbonation reaction. Nano-sized calcium carbonate is prepared by controlling process conditions such as reaction temperature, concentration, gas-liquid ratio, and additives. While this method requires low equipment investment and is simple to operate, it suffers from high energy consumption, poor gas-liquid contact, long carbonation time, difficulty in process control, wide particle size distribution, and inhomogeneous crystal structure.

[0004] Continuous spray carbonation involves introducing kiln gas containing carbon dioxide from the bottom of the tower, which then flows counter-currently into contact with lime slurry sprayed at the top of the tower in droplet size, thus initiating the carbonation reaction. While this method offers high efficiency and easy particle size control in the production of nano-calcium carbonate, it suffers from drawbacks such as high equipment investment, long carbonation time, and less than ideal dispersion of the finished product. Summary of the Invention

[0005] The purpose of this invention is to provide a process for preparing nano-calcium carbonate based on carbonation. This invention features a large gas-liquid contact area, short carbonation time, and a uniform, stable, and well-dispersible finished product.

[0006] The technical solution of this invention: a process for preparing nano-calcium carbonate based on carbonation, comprising the following steps: S1. Mix calcium hydroxide emulsion with hydrogen peroxide, then spray the mixture into the reactor as a mist. A mixture of carbon dioxide and nitrogen gas is introduced into the reactor under high pressure, forming a nanoscale three-dimensional gas flow network that mixes with the calcium hydroxide emulsion for a carbonation reaction. This is followed by high-intensity shearing to obtain calcium carbonate slurry. In the initial stage of the carbonation reaction, the carbon dioxide concentration is 30-50%, and the flow rate of the mixed gas is 0.7-2 L / min. When the pH of the calcium hydroxide emulsion is 8-12, the carbon dioxide concentration is 20-30%, and the flow rate of the mixed gas is 0.5-0.7 L / min. When the pH of the calcium hydroxide emulsion reaches 8-10, water, ethanol, and a dispersant are added, with the carbon dioxide concentration at 30-40% and the flow rate of the mixed gas at 0.7-1 L / min, until the pH of the calcium hydroxide emulsion reaches 6.5-7.0. S2. First, add fatty acids to the calcium carbonate slurry and mix well. Then, add magnesium sulfate and mix well to obtain modified calcium carbonate. S3. The modified calcium carbonate is centrifuged, dried, and pulverized to obtain nano-calcium carbonate powder.

[0007] In the aforementioned process for preparing nano-calcium carbonate based on carbonation, the preparation method of calcium hydroxide emulsion is as follows: limestone is calcined at 1000~1100℃, the heating rate is set to 8~15℃ / min, and the holding time is 1~3h to obtain quicklime powder; the quicklime powder is ground, passed through a 200-mesh sieve, filtered, and added to deionized water at 60~90℃ according to a solid-liquid molar ratio of 1:15~30. The mixture is stirred at a constant temperature for 1~3h to obtain a calcium hydroxide emulsion with a mass fraction of 15~20%.

[0008] In the aforementioned process for preparing nano-calcium carbonate based on carbonation, the inlet temperature of the reactor is 15~25℃, the middle section temperature is 25~30℃, and the outlet temperature is 30~40℃.

[0009] In the aforementioned process for preparing nano-calcium carbonate based on carbonation, the gas discharged from the reactor is reintroduced into the reactor, and the slurry discharged from the reactor is reintroduced into the reactor.

[0010] In the aforementioned process for preparing nano-calcium carbonate based on carbonation, the mixed gas in step S1 is mixed with calcium hydroxide emulsion in the form of nanoparticles in the reactor.

[0011] In the aforementioned process for preparing nano-calcium carbonate based on carbonation, the dispersant includes methanol, sodium polyacrylate, or polyvinylpyrrolidone.

[0012] In the aforementioned process for preparing nano-calcium carbonate based on carbonation, the reactor includes a main body. The upper end of the main body is provided with an inlet pipe, an exhaust pipe, and a feed pipe. The exhaust pipe is connected to the inlet pipe and is equipped with a carbon dioxide detector. The inlet pipe is equipped with a first regulating valve, and the feed pipe is equipped with a second regulating valve. The interior of the main body is provided with a first carbonization zone and a second carbonization zone. Multiple outlet pipes connected to the inlet pipe are evenly distributed within the first carbonization zone. Each outlet pipe has evenly distributed micropores, and the exterior of the outlet pipe is covered with a nanoporous membrane. Multiple atomizing nozzles are provided on the feed pipe within the first carbonization zone. A shearing assembly is provided within the second carbonization zone. The lower end of the main body is provided with a discharge pipe connected to the feed pipe, and a pH detector is provided on the discharge pipe.

[0013] In the aforementioned process for preparing nano-calcium carbonate based on carbonation, the shearing assembly includes a horizontally distributed stirring shaft driven by a motor, a stirring blade in the middle of the stirring shaft, turbine shearing disks at both ends of the stirring shaft, and an annularly distributed, upwardly curved arc-shaped baffles on the inner wall of the main body below the stirring shaft. The upper surface of the arc-shaped baffles is provided with several serrated shearing strips, and filter holes are also provided on the arc-shaped baffles.

[0014] In the aforementioned process for preparing nano-calcium carbonate based on carbonation, the stirring blades include a first stirring blade distributed horizontally, and second stirring blades inclined to both sides of the first stirring blade; the shearing blades of the turbine shearing disk are curved, and the bending directions of two adjacent shearing blades are different.

[0015] In the aforementioned process for preparing nano-calcium carbonate based on carbonation, the main body is provided with a jacket, and independent temperature regulating pipes are provided in the inlet section, middle section and outlet section of the main body inside the jacket. Heating oil or cooling liquid is provided in the temperature regulating pipes.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention mixes calcium hydroxide emulsion with hydrogen peroxide. The tiny oxygen bubbles generated by the decomposition of hydrogen peroxide create disturbance in the solution, preventing the agglomeration of nano-calcium carbonate particles, resulting in finer and more uniform particles and an increased specific surface area. The mixed gas forms a nanoscale gas flow network under high pressure, which contacts the atomized calcium hydroxide emulsion, increasing the gas-liquid contact area, limiting crystal nucleus growth, accelerating the carbonation reaction, and using N2 microbubbles to guide the directional deposition of calcium carbonate at the gas-liquid interface, allowing for full crystal development. Then, high-intensity shear force is used to break up the anisotropic crystal nuclei, promoting spherical agglomeration, resulting in uniform crystal distribution, reducing carbonation dead zones, and obtaining spherical nano-calcium carbonate without the need for crystal form control agents, thus eliminating the need for post-processing with crystal form control agents.

[0017] In the initial stage of the carbonization reaction, the carbon dioxide concentration is 30-50% to provide sufficient carbon source, promote rapid nucleation, and form a large number of tiny crystal nuclei, laying the foundation for subsequent spherical particle growth. The flow rate of the mixed gas is 0.7-2 L / min to enhance gas-liquid mass transfer efficiency, avoid explosive nucleation caused by local supersaturation, shorten the induction period, and increase the reaction rate. When the pH of the calcium hydroxide emulsion is 8-12, the carbon dioxide concentration is 20-30%. Lowering the CO2 concentration can slow down the carbonization rate and avoid particle coarsening or agglomeration due to excessively rapid reaction. The flow rate of the mixed gas is 0.5-0.7 L / min to match the carbonization rate, making crystal growth more uniform and reducing the risk of secondary oxidation. Secondary nucleation interference stabilizes the target crystal form, balances growth kinetics, and yields intermediate products with better monodispersity. When the pH of the calcium hydroxide emulsion reaches 8-10, water, ethanol, and a dispersant are added to dilute the calcium hydroxide, reduce viscosity and liquid-solid interface energy, promote isotropic crystal growth, prevent the agglomeration of formed crystals, improve dispersibility, and reduce particle size distribution width. The carbon dioxide concentration is 30-40%, and the concentration is appropriately increased to complete the carbonization of residual Ca(OH)2. The flow rate of the mixed gas is 0.7-1 L / min until the pH of the calcium hydroxide emulsion reaches 6.5-7.0, so that the final product has a narrow particle size distribution, high sphericity, and good crystal stability. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the reactor structure of the present invention.

[0019] Figure 2 This is a schematic diagram of the air outlet pipe.

[0020] Figure 3 This is a schematic diagram of the arc-shaped baffle.

[0021] Figure 4 This is a schematic diagram of the turbine shear disc.

[0022] The labels in the attached diagram are as follows: 1. Main body; 11. Inlet pipe; 12. Exhaust pipe; 13. Feed pipe; 14. Carbon dioxide detector; 15. First control valve; 16. Second control valve; 17. Discharge pipe; 18. pH detector; 21. First carbonization zone; 22. Outlet pipe; 23. Micropore; 24. Nanoporous membrane; 31. Second carbonization zone; 32. Motor; 33. Stirring shaft; 341. First stirring paddle; 342. Second stirring paddle; 35. Turbine shearing disc; 351. Shearing blade; 36. Arc-shaped baffle; 361. Shearing strip; 362. Filter hole; 41. Jacket; 42. Temperature regulating pipe. Detailed Implementation

[0023] The present invention will be further described below with reference to embodiments, but these embodiments are not intended to limit the scope of the invention.

[0024] Example: The process for preparing nano-calcium carbonate based on the carbonation method includes the following steps: S1. Calcinate limestone at 1000~1100℃, set the heating rate to 8~15℃ / min, and the holding time to 1~3h to obtain quicklime powder; grind the quicklime powder, pass it through a 200-mesh sieve, filter it, and add it to deionized water at 60~90℃ according to a solid-liquid molar ratio of 1:15~30. Stir at a constant temperature for 1~3h to obtain a calcium hydroxide emulsion with a mass fraction of 15~20%. S2. Mix calcium hydroxide emulsion with hydrogen peroxide and then spray it into the reactor in a mist. A mixture of carbon dioxide and nitrogen gas is introduced into the reactor under high pressure to form a nanoscale three-dimensional airflow network that mixes with the calcium hydroxide emulsion. Then, high-intensity shearing is performed to fully carry out the carbonation reaction and obtain calcium carbonate slurry. The tiny oxygen bubbles generated by the decomposition of hydrogen peroxide create disturbances in the solution, preventing the agglomeration of nano-calcium carbonate particles, resulting in finer and more uniform particles and an increased specific surface area. The mixed gas forms a nanoscale gas flow network that contacts the atomized calcium hydroxide emulsion, increasing the gas-liquid contact area, limiting crystal nucleus growth, accelerating the carbonation reaction, and using N2 microbubbles to guide the directional deposition of calcium carbonate at the gas-liquid interface, allowing for full crystal development. Then, the anisotropic crystal nuclei are broken by high-intensity shear force, promoting spherical agglomeration, resulting in uniform crystal distribution, reducing carbonation dead zones, and obtaining spherical nano-calcium carbonate without the need for crystal form control agents, thus eliminating the need for post-processing with crystal form control agents.

[0025] In the initial stage of the carbonization reaction, the carbon dioxide concentration is 30-50% to provide sufficient carbon source, promote rapid nucleation, and form a large number of tiny crystal nuclei, laying the foundation for subsequent spherical particle growth. The flow rate of the mixed gas is 0.7-2 L / min to enhance gas-liquid mass transfer efficiency, avoid explosive nucleation caused by local supersaturation, shorten the induction period, and increase the reaction rate. When the pH of the calcium hydroxide emulsion is 8-12, the carbon dioxide concentration is 20-30%. Lowering the CO2 concentration can slow down the carbonization rate and avoid particle coarsening or agglomeration due to excessively rapid reaction. The flow rate of the mixed gas is 0.5-0.7 L / min to match the carbonization rate, making crystal growth more uniform and reducing the risk of secondary oxidation. Secondary nucleation interference stabilizes the target crystal form, balances growth kinetics, and yields intermediate products with better monodispersity. When the pH of the calcium hydroxide emulsion reaches 8-10, water, ethanol, and a dispersant are added to dilute the calcium hydroxide, reduce viscosity and liquid-solid interface energy, promote isotropic crystal growth, prevent the agglomeration of formed crystals, improve dispersibility, and reduce particle size distribution width. The carbon dioxide concentration is 30-40%, and the concentration is appropriately increased to complete the carbonization of residual Ca(OH)2. The flow rate of the mixed gas is 0.7-1 L / min until the pH of the calcium hydroxide emulsion reaches 6.5-7.0, so that the final product has a narrow particle size distribution, high sphericity, and good crystal stability.

[0026] The reactor has an inlet temperature of 15-25℃, a middle section temperature of 25-30℃, and an outlet temperature of 30-40℃. Adjusting the temperature of different sections allows the carbonization process to proceed under segmented temperature control, utilizing the heat of the carbonization reaction. At the low inlet temperature (15-25℃), the solubility of Ca(OH)₂ decreases, prolonging the nucleation induction period and promoting the formation of small, uniform crystal nuclei. In the middle section, the temperature is raised to 25-30℃ to accelerate CO₂ mass transfer, achieving crystal size uniformity. At the outlet temperature, the temperature is raised to 30-40℃ to increase the residual carbonization rate of Ca(OH)₂, which is beneficial for the surface reconstruction of spherical particles.

[0027] The gas discharged from the reactor is reintroduced into the reactor for recycling, reducing waste gas emissions; the slurry discharged from the reactor is also reintroduced into the reactor for repeated processing, improving reaction efficiency and reducing resource waste.

[0028] The dispersant includes methanol, sodium polyacrylate, or polyvinylpyrrolidone.

[0029] S3. First, add fatty acids to the calcium carbonate slurry and mix evenly. Then, add magnesium sulfate and mix evenly to obtain modified calcium carbonate. The added fatty acids, including stearic acid and oleic acid, can change the hydrophilic and hydrophobic properties of the particle surface and effectively prevent the adhesion between particles due to collision. The addition of magnesium sulfate increases the charge on the surface of the calcium carbonate particles, improves the stability of the stearic acid coating layer, and the adsorbed divalent ions are easy to form bonds with fatty acids, thereby increasing the adsorption amount and adsorption strength of fatty acids on the particle surface.

[0030] S4. The modified calcium carbonate is centrifuged, dried, and pulverized to obtain nano-calcium carbonate powder.

[0031] like Figure 1 and Figure 2 As shown, the reactor includes a main body 1. The upper end of the main body 1 is provided with an inlet pipe 11, an exhaust pipe 12, and a feed pipe 13. The exhaust pipe 12 is connected to the inlet pipe 11 and is equipped with a carbon dioxide detector 14. The inlet pipe 11 is equipped with a first regulating valve 15, and the feed pipe 13 is equipped with a second regulating valve 16. The interior of the main body 1 is provided with a first carbonization zone 21 and a second carbonization zone 31. Multiple outlet pipes 22 connected to the inlet pipe 11 are evenly distributed in the first carbonization zone 21. Each outlet pipe 22 is evenly distributed with micropores 23. The exterior of the outlet pipe 22 is covered with a nanoporous membrane 24. Multiple atomizing nozzles are provided on the feed pipe 13 located in the first carbonization zone 21. A shearing component is provided in the second carbonization zone 31. The lower end of the main body 1 is provided with an outlet pipe 17, which is connected to the feed pipe 13. A pH detector 18 is provided on the outlet pipe 17.

[0032] In the first carbonization zone 21, the mixed gas, through the outlet pipe 22 and the nanoporous membrane 24, improves the distribution of carbon dioxide, forming a nanoscale three-dimensional gas flow network, increasing the gas-liquid contact area, and achieving thorough micro-mixing with the calcium hydroxide slurry. This reduces carbonization dead zones, accelerates the carbonization reaction, and improves carbonization uniformity and nucleation rate. In the second carbonization zone 31, the mixed gas and calcium hydroxide slurry are also subjected to vigorous mixing and pulverization by a shearing component, resulting in a high degree of mixing of the gas, liquid, and solid phases. Furthermore, the gas is fed from the top of the reactor, resulting in a high concentration of carbon dioxide at the top and a low concentration at the bottom, which matches the decreasing concentration of calcium hydroxide. This is beneficial for the formation of a large number of calcium carbonate crystal nuclei in the early stage of carbonization, limiting crystal growth and promoting the ultrafine and nano-sized particles.

[0033] The gas discharged from the reactor is reused by entering the inlet pipe 11 through the exhaust pipe 12, and the slurry discharged from the reactor is recycled through the discharge pipe 17 into the feed pipe 13 for repeated processing. This helps to reduce the ineffective emission of CO2 and improve the uniform growth of calcium carbonate particles and the regularity of crystal morphology.

[0034] The concentration of carbon dioxide in the exhaust gas is detected by carbon dioxide detector 14, and the pH value is detected in real time by pH detector 18, so as to better regulate the concentration and flow rate of carbon dioxide.

[0035] Therefore, the reactor of the present invention combines micro-mixing and macro-mixing to mix carbon dioxide and calcium hydroxide slurry, thereby accelerating the reaction rate and allowing for repeated recycling, improving the controllability of process conditions and the sufficiency of the reaction, and ensuring the uniformity and completeness of the product.

[0036] like Figure 1 and Figure 3 As shown, the shearing assembly includes a horizontally distributed stirring shaft 33 driven by a motor 32. The stirring shaft 33 has stirring blades in the middle and turbine shearing disks 35 at both ends. The inner wall of the main body 1 below the stirring shaft 33 has annularly distributed upward curved arc baffles 36. The upper surface of the arc baffles 36 has several serrated shearing strips 361, and the arc baffles 36 also have filter holes 362.

[0037] In the second carbonization zone 31, the combination of the stirring impeller, turbine shear disk 35, and arc-shaped baffle 36 enables radial and axial shear strengthening of the slurry, breaks down anisotropic crystal nuclei, and maximizes the turbulence of the slurry. Simultaneously, the downward-precipitating, incompletely carbonized calcium hydroxide is thrown towards the first carbonization zone 21 by the centrifugal force of the stirring impeller and turbine shear disk 35, where it is thoroughly mixed and carbonized again with high-concentration carbon dioxide, improving carbonization efficiency and shortening carbonization time. Furthermore, the annularly distributed arc-shaped baffle 36 also serves a guiding function.

[0038] The stirring blades include a horizontally distributed first stirring blade 341, and second stirring blades 342 inclined to both sides of the first stirring blade 341; as shown Figure 4 As shown, the shear blades 351 of the turbine shear disk 35 are curved, and the curvature directions of adjacent shear blades 351 are different. The first stirring impeller 341 and the second stirring impeller 342 generate thrust in different directions, pushing the slurry towards the arc-shaped baffle 36 and the turbine shear disk 35 respectively to enhance the shearing effect; the adjacent curved shear blades 351 can increase the turbulence of the slurry, thereby increasing the mixing degree of carbon dioxide and calcium hydroxide slurry and the degree of carbonization reaction.

[0039] The main body 1 is provided with a jacket 41. Inside the jacket 41, independent temperature regulating pipes 42 are respectively located at the inlet section, middle section, and outlet section of the main body 1. The temperature regulating pipes 42 are filled with heating oil or cooling liquid. The temperature regulating pipes 42 at different locations heat or cool different parts of the reactor in stages, so as to better control the temperature of each section and each reaction stage in the reactor, thereby better controlling the carbonization reaction process.

[0040] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Those skilled in the art can modify the technical solutions described in the above embodiments, or make equivalent substitutions for some of the technical features; and all such modifications and substitutions should fall within the protection scope of the appended claims of the present invention.

Claims

1. A process for preparing nano-calcium carbonate based on carbonation, characterized in that: Includes the following steps: S1. Mix calcium hydroxide emulsion with hydrogen peroxide, then spray the mixture into the reactor as a mist. A mixture of carbon dioxide and nitrogen gas is introduced into the reactor under high pressure, forming a nanoscale three-dimensional gas flow network that mixes with the calcium hydroxide emulsion for a carbonation reaction. This is followed by high-intensity shearing to obtain calcium carbonate slurry. In the initial stage of the carbonation reaction, the carbon dioxide concentration is 30-50%, and the flow rate of the mixed gas is 0.7-2 L / min. When the pH of the calcium hydroxide emulsion is 8-12, the carbon dioxide concentration is 20-30%, and the flow rate of the mixed gas is 0.5-0.7 L / min. When the pH of the calcium hydroxide emulsion reaches 8-10, water, ethanol, and a dispersant are added, with the carbon dioxide concentration at 30-40% and the flow rate of the mixed gas at 0.7-1 L / min, until the pH of the calcium hydroxide emulsion reaches 6.5-7.

0. S2. First, add fatty acids to the calcium carbonate slurry and mix well. Then, add magnesium sulfate and mix well to obtain modified calcium carbonate. S3. The modified calcium carbonate is centrifuged, dried, and pulverized to obtain nano-calcium carbonate powder.

2. The process for preparing nano-calcium carbonate based on carbonation according to claim 1, characterized in that: The preparation method of calcium hydroxide emulsion is as follows: limestone is calcined at 1000~1100℃, the heating rate is set at 8~15℃ / min, and the holding time is 1~3h to obtain quicklime powder; the quicklime powder is ground, passed through a 200-mesh sieve, filtered, and added to deionized water at 60~90℃ at a solid-liquid molar ratio of 1:15~30 and stirred at a constant temperature for 1~3h to obtain calcium hydroxide emulsion with a mass fraction of 15~20%.

3. The process for preparing nano-calcium carbonate based on carbonation according to claim 1, characterized in that: The inlet temperature of the reactor is 15~25℃, the middle section temperature is 25~30℃, and the outlet temperature is 30~40℃.

4. The process for preparing nano-calcium carbonate based on carbonation according to claim 1, characterized in that: The gas discharged from the reactor is reintroduced into the reactor, and the slurry discharged from the reactor is also reintroduced into the reactor.

5. The process for preparing nano-calcium carbonate based on carbonation according to claim 1, characterized in that: In step S1, the mixed gas is mixed with calcium hydroxide emulsion in the form of nanoparticles in the reactor.

6. The process for preparing nano-calcium carbonate based on carbonation according to claim 1, characterized in that: The dispersant includes methanol, sodium polyacrylate, or polyvinylpyrrolidone.

7. The process for preparing nano-calcium carbonate based on carbonation according to claim 1, characterized in that: The reactor includes a main body (1), with an inlet pipe (11), an exhaust pipe (12), and a feed pipe (13) at the upper end of the main body (1). The exhaust pipe (12) is connected to the inlet pipe (11), and a carbon dioxide detector (14) is installed on the exhaust pipe (12). A first control valve (15) is installed on the inlet pipe (11), and a second control valve (16) is installed on the feed pipe (13). The interior of the main body (1) is provided with a first carbonization zone (21) and a second carbonization zone (31). The first carbonization zone (21) is uniformly divided into... The main body (1) has multiple outlet pipes (22) connected to the inlet pipe (11). Each outlet pipe (22) has micropores (23) evenly distributed on it. The outlet pipe (22) is covered with a nanoporous membrane (24). The feed pipe (13) is equipped with multiple atomizing nozzles in the first carbonization zone (21). The second carbonization zone (31) is equipped with a shearing component. The lower end of the main body (1) is equipped with an outlet pipe (17), which is connected to the feed pipe (13). The outlet pipe (17) is equipped with a pH detector (18).

8. The process for preparing nano-calcium carbonate based on carbonation according to claim 1, characterized in that: The shearing assembly includes a horizontally distributed stirring shaft (33) driven by a motor (32). The stirring shaft (33) has stirring blades in the middle and turbine shearing discs (35) at both ends. The inner wall of the main body (1) below the stirring shaft (33) has annularly distributed upward curved baffles (36). The upper surface of the curved baffles (36) has several serrated shearing strips (361). The curved baffles (36) also have filter holes (362).

9. The process for preparing nano-calcium carbonate based on carbonation according to claim 1, characterized in that: The stirring blades include a first stirring blade (341) distributed horizontally, and a second stirring blade (342) inclined to both sides of the first stirring blade (341); the shear blades (351) of the turbine shear disk (35) are curved, and the bending directions of two adjacent shear blades (351) are different.

10. The process for preparing nano-calcium carbonate based on carbonation according to claim 1, characterized in that: The main body (1) is provided with a jacket (41) on the outside. The jacket (41) is provided with independent temperature regulating pipes (42) in the inlet section, middle section and outlet section of the main body (1). The temperature regulating pipes (42) are provided with heating oil or coolant.

Images