Nano calcium carbonate activation method

Abstract

The invention relates to the related technical field of nano calcium carbonate activation, and discloses a nano calcium carbonate activation method, which comprises a pretreatment unit, a reaction tank, an activator adding device, a dispersing device and a control system, the pretreatment unit consists of a raw material crushing module and a screening module which are connected in series, and is used for crushing a calcium carbonate raw material into micron-sized particles. Accurate activation control is achieved through modular design, the system comprises a pretreatment unit, a multi-cavity reaction tank, an activating agent gradient adding device and a composite dispersion device, and through staged temperature control and activating agent proportion optimization and in combination with a mechanical-ultrasonic synergistic dispersion technology, the activation efficiency is improved. The nano calcium carbonate is uniformly activated and coated, and the interface bonding is enhanced after stearic acid forms a basic coating layer and a silane coupling agent through a staged activator adding strategy, so that the activation process is stably and orderly carried out.

Description

Technical Field

[0001] The present invention relates to the technical field related to the activation of nano calcium carbonate, and in particular to a method for activating nano calcium carbonate. Background Art

[0002] Activating nano calcium carbonate is a method for making the surface activity of nano calcium carbonate, so as to greatly improve its performance, such as significantly enhancing the effects in terms of dispersibility, compatibility, etc.

[0003] Most of the existing methods for activating nano calcium carbonate, such as traditional dry activation, have the problem of uneven dispersion, resulting in poor activation effect of nano calcium carbonate; while the energy consumption for activating nano calcium carbonate by wet process is high, which is not conducive to cost saving; and the above processes also have problems such as poor coating effect of the activator. In order to solve such problems, a method for activating nano calcium carbonate is proposed. Summary of the Invention

[0004] The present invention provides a method for activating nano calcium carbonate, which solves the problems in the above background art.

[0005] The present invention solves its technical problems by adopting the following technical solutions:

[0006] A nano calcium carbonate activation system includes a pretreatment unit, a reaction tank, an activator adding device, a dispersion device, and a control system;

[0007] The pretreatment unit is composed of a raw material crushing module and a screening module connected in series, and is used for crushing calcium carbonate raw materials into micron-sized particles;

[0008] The reaction tank is provided with an airtight feed port at the top, which is communicated with the outlet of the pretreatment unit, and a spiral stirring paddle and a temperature sensor are installed at the bottom;

[0009] The activator adding device is connected to the liquid injection port on the side wall of the reaction tank through a metering pump, and includes a stearic acid storage tank and a silane coupling agent storage tank arranged in parallel;

[0010] The dispersion device is connected to the outlet of the reaction tank and includes a high-speed shear disperser and an ultrasonic oscillator connected in series in three stages;

[0011] The control system is electrically connected to the temperature sensor, the metering pump and the dispersion device respectively, and is used for dynamically adjusting the activator adding rate and the dispersion intensity.

[0012] Preferably, the screening module of the pretreatment unit adopts a double-layer vibrating screen mesh, the upper layer is a 100-200 mesh stainless steel screen mesh, and the lower layer is an electrostatic adsorption device.

[0013] Preferably, the inner wall of the reaction tank is provided with a polytetrafluoroethylene coating, and the blades of the spiral stirring paddle are staggered at an inclination angle of 45°.

[0014] Preferably, the working cavity of the high-speed shearing disperser is provided with a guide vane, and its rotation direction is set in the reverse direction to the material flow direction.

[0015] A method for activating nano calcium carbonate includes the following steps:

[0016] S1: After pre-treating the calcium carbonate raw material, it is transported to the reaction tank;

[0017] S2: The activator is added in two stages. In the first stage, stearic acid is injected and the temperature is controlled at 60 - 80 °C. In the second stage, a silane coupling agent is injected and the temperature is raised to 90 - 110 °C;

[0018] S3: The activation treatment is completed by synchronous mechanical shearing and ultrasonic oscillation, and the total duration is controlled within 30 - 50 minutes.

[0019] Preferably, in S2, the mass ratio of the two-stage activator is 1:0.3 - 0.6, and the heating rate in the second stage is 2 - 3 °C / min.

[0020] Preferably, in S3, the rotational speed gradient of the high-speed shearing disperser changes. In the initial stage, it is 1000 - 1500 rpm, and in the final stage, it is increased to 2000 - 2500 rpm.

[0021] Preferably, it further includes setting an on-line particle size detector at the outlet of the dispersing device to adjust the working mode of the ultrasonic power in real-time feedback.

[0022] The advantages and positive effects of the present invention are: precise activation control is achieved through modular design, and the system includes a pre-treatment unit, a multi-chamber reaction tank, an activator gradient addition device, and a composite dispersing device. Through staged temperature control and activator ratio optimization, combined with mechanical-ultrasonic synergistic dispersion technology, the purpose of uniform activation and coating layer of nano calcium carbonate is achieved. Moreover, through the staged activator addition strategy, stearic acid first forms a basic coating layer, and the silane coupling agent then enhances the interfacial bonding, thus ensuring the stable and orderly progress of the activation process. Description of the Drawings

[0023] The present invention will be further described below with reference to the drawings and embodiments.

[0024] Figure 1 It is a schematic flow structure diagram of the activation system in the present invention.

[0025] The marks in the drawings are described separately as follows:

[0026] 1. Pre-treatment unit; 11. Raw material crushing module; 12. Screening module;

[0027] 2. Reaction tank; 21. Airtight feeding port; 22. Outlet of pretreatment unit; 23. Screw agitator; 24. Temperature sensor;

[0028] 3. Activator adding device; 31. Dosing pump; 32. Stearic acid storage tank; 33. Silane coupling agent storage tank;

[0029] 4. Dispersion device; 41. High-speed shear disperser; 42. Ultrasonic oscillator;

[0030] 5. Control system. Detailed implementation mode

[0031] Now, the present invention will be further described in detail with reference to the accompanying drawings. These drawings are all simplified schematic diagrams, only illustrating the basic structure of the present invention in a schematic manner, so they only show the components related to the present invention.

[0032] The following further details the embodiments of the present invention with reference to the accompanying drawings:

[0033] Refer to Figure 1 As shown, the activation of nano calcium carbonate is a method for surface activation of nano calcium carbonate to greatly improve its performance, such as significantly enhancing the effects in terms of dispersibility, compatibility, etc.

[0034] Most existing methods for activating nano calcium carbonate, such as traditional dry activation, have the problem of uneven dispersion, resulting in poor activation effect of nano calcium carbonate; while the energy consumption for activating nano calcium carbonate through wet process is high, which is not conducive to cost saving; and the above processes also have problems such as poor coating effect of the activator. To solve such problems, a nano calcium carbonate activation system is proposed, including a pretreatment unit 1, a reaction tank 2, an activator adding device 3, a dispersion device 4, and a control system 5;

[0035] The pretreatment unit 1 is composed of a raw material crushing module 11 and a screening module 12 connected in series, and is used for crushing calcium carbonate raw materials into micron-sized particles;

[0036] The reaction tank 2 is provided with an airtight feeding port 21 at the top, which is communicated with the outlet of the pretreatment unit 1, and a screw agitator 23 and a temperature sensor 24 are installed at the bottom;

[0037] The activator adding device 3 is connected to the liquid injection port on the side wall of the reaction tank 2 through a dosing pump 31, and includes a stearic acid storage tank 32 and a silane coupling agent storage tank 33 arranged in parallel;

[0038] The dispersion device 4 is connected to the outlet of the reaction tank 2, and includes a high-speed shear disperser 41 and an ultrasonic oscillator 42 connected in series in three stages;

[0039] The control system 5 is electrically connected to the temperature sensor 24, the metering pump 31, and the dispersion device 4 respectively, and is used to dynamically adjust the addition rate of the activator and the dispersion intensity; precise activation control is achieved through modular design, and the system includes a pretreatment unit 1, a multi-chamber reaction tank 2, an activator gradient addition device, and a composite dispersion device 4. Through staged temperature control and activator ratio optimization, combined with mechanical-ultrasonic synergistic dispersion technology, the purpose of uniform activation of nano-calcium carbonate and a coating layer is achieved. Moreover, through a staged activator addition strategy, stearic acid first forms a basic coating layer, and the silane coupling agent then enhances the interfacial bonding, thereby ensuring the stable and orderly progress of the activation process.

[0040] It should be noted that the screening module 12 of the above-mentioned pretreatment unit 1 adopts a double-layer vibrating screen mesh. The upper layer is a 100-200 mesh stainless steel screen mesh, and the lower layer is an electrostatic adsorption device; through the setting of the double-layer vibrating screen mesh, the best pre-treatment effect on nano-calcium carbonate can be achieved.

[0041] Moreover, the specific treatment process is as follows: The heavy calcium carbonate lumps are put into the pretreatment unit 1, crushed by a double-roll crusher and then enter the vibrating screening module 12. The particles with a size of ≥150 meshes on the screen are returned for re-crushing, and the materials under the screen are removed of metal debris through an electrostatic adsorption plate, and finally the pre-treated raw materials with D90 ≤ 50 μm are obtained.

[0042] Furthermore, in this embodiment, the entire activation process is divided into two stages, and the specific steps of the activation method are as follows:

[0043] S1: The calcium carbonate raw materials are transported to the reaction tank 2 after pretreatment;

[0044] S2: The activator is added in two stages. In the first stage, stearic acid is injected and the temperature is controlled at 60 - 80 °C. In the second stage, the silane coupling agent is injected and the temperature is raised to 90 - 110 °C;

[0045] S3: The activation treatment is completed through synchronous mechanical shearing and ultrasonic oscillation, and the total duration is controlled within 30 - 50 minutes.

[0046] It should be noted that the activation in the first stage is as follows: The pre-treated raw materials are injected into the reaction tank 2 through an airtight feed port, the spiral stirring paddle 23 is started to run at a speed of 200 rpm, the stearic acid solution is injected through the metering pump 31 at a rate of 5 mL / min, and at the same time, the temperature of the material is stabilized at 75 ± 2 °C through jacket heating for 40 minutes; through the above treatment, effective prevention of material sticking to the wall can be achieved, and the staggered stirring paddle blade design forms a three-dimensional eddy current, enabling the activator to fully contact the particles.

[0047] It should also be noted that the above-mentioned second-stage activation process is as follows: heating up to 105°C at a rate of 2.5°C / min, switching to the silane coupling agent storage tank 33, adjusting the injection rate to 3 mL / min, simultaneously increasing the stirring speed to 350 rpm, maintaining the temperature fluctuation range ≤ ±1°C, and realizing zero-contact switching of the activator through the above structure to avoid cross-contamination.

[0048] Furthermore, pump the activated slurry into the dispersion device 4. First, break the aggregates through the coarse dispersion impeller (1500 rpm) of the high-speed shear disperser 41, then refine the particles with the medium shear impeller (2200 rpm), and finally, the fine grinding disc (2500 rpm) and the 28 kHz ultrasonic oscillator 42 act synchronously for 20 minutes. Through the synergistic effect of the three-stage shear gradient and the ultrasonic cavitation effect, the difference in the coating layer thickness on the surface of the nanoparticles is controlled within the range of ±2 nm.

[0049] It is worth mentioning that an online laser particle size analyzer can also be installed at the outlet of the dispersion device 4 to detect the D50 value in real time and feedback to adjust the ultrasonic power. When D50 > 100 nm, the power is automatically increased by 10% until the set threshold is reached.

[0050] It should be emphasized that the embodiments described in the present invention are illustrative rather than restrictive. Therefore, the present invention is not limited to the embodiments described in the specific embodiments. Any other embodiments obtained by those skilled in the art based on the technical solutions of the present invention also fall within the scope of protection of the present invention.

Claims

1. A nano calcium carbonate activation system, characterized in that: It includes a pretreatment unit (1), a reaction tank (2), an activator addition device (3), a dispersion device (4), and a control system (5); The pretreatment unit (1) is composed of a raw material crushing module (11) and a screening module (12) connected in series, and is used to crush the calcium carbonate raw material into micron-sized particles; The reaction tank (2) is provided with an airtight feed port (21) at the top, which is communicated with the outlet of the pretreatment unit (1), and a spiral agitator (23) and a temperature sensor (24) are installed at the bottom; The activator addition device (3) is connected to the liquid injection port on the side wall of the reaction tank (2) through a metering pump (31), and includes a stearic acid storage tank (32) and a silane coupling agent storage tank (33) arranged in parallel; The dispersion device (4) is connected to the outlet of the reaction tank (2), and includes a high-speed shear disperser (41) and an ultrasonic oscillator (42) connected in series in three stages; The control system (5) is electrically connected to the temperature sensor (24), the metering pump (31), and the dispersion device (4) respectively, and is used to dynamically adjust the activator addition rate and the dispersion intensity.

2. The nano calcium carbonate activation system according to claim 1, wherein: The screening module (12) of the pretreatment unit (1) adopts a double-layer vibrating screen mesh. The upper layer is a 100-200 mesh stainless steel screen mesh, and the lower layer is an electrostatic adsorption device.

3. The nano calcium carbonate activation system according to claim 1, wherein: The inner wall of the reaction tank (2) is provided with a polytetrafluoroethylene coating, and the blades of the spiral agitator (23) are staggered at an inclination angle of 45°.

4. A nano-calcium carbonate activation system according to claim 1, characterized in that: The working cavity of the high-speed shear disperser (41) is internally provided with guide vanes, and its rotation direction is set in the reverse direction to the material flow direction.

5. A method for activating nano-calcium carbonate based on the system of any one of claims 1-4, characterized in that: It includes the following steps: S1: The calcium carbonate raw material is pretreated and then transported to the reaction tank (2); S2: The activator is added in two stages. In the first stage, stearic acid is injected and the temperature is controlled at 60-80 °C. In the second stage, the silane coupling agent is injected and the temperature is raised to 90-110 °C; S3: The activation treatment is completed through synchronous mechanical shearing and ultrasonic oscillation, and the total duration is controlled within 30-50 minutes.

6. The method for activating nano calcium carbonate according to claim 5, characterized in that: In S2, the mass ratio of the two-stage activator is 1:0.3-0.6, and the heating rate in the second stage is 2-3 °C / min.

7. A method for activating nano calcium carbonate according to claim 5, characterized in that: In S3, the rotational speed gradient of the high-speed shear disperser (41) changes. The initial stage is 1000-1500 rpm, and it is increased to 2000-2500 rpm at the final stage.

8. A method for activating nano calcium carbonate according to claim 5, characterized in that: It also includes setting an on-line particle size detector at the outlet of the dispersion device (4) to provide real-time feedback for adjusting the ultrasonic power working mode.

Images