Controllable preparation method of calcium carbonate under power plant flue gas-ammonia-calcium system

Abstract

The invention provides a controllable preparation method of calcium carbonate under a flue gas-ammonia-calcium system of a power plant, which comprises the following steps: putting a mixed solution of ammonia water, calcium chloride and ammonium chloride into a reaction container, and adjusting the pH value range of the mixed solution to 9-10; power plant flue gas is cooled after being subjected to dust removal, desulfurization and denitration pretreatment, and is introduced into the bottom of the reaction container; in the process of continuously introducing the flue gas of the power plant into the reaction container, slowly adding a calcium carbonate product control agent solution which comprises chitosan, poly (dimethylaminoethyl methacrylate), D-sodium gluconate, L-glutamic acid and water, and fully reacting; and after the reaction is finished, carrying out solid-liquid separation on the generated calcium carbonate slurry, and drying to obtain the calcite type calcium carbonate. According to the method, nucleation, growth and other links of calcium carbonate can be regulated and controlled, so that the granularity, crystal form and the like of the product are controlled according to requirements, the stability and consistency of the product quality are improved, and the requirements of different application scenes on high-quality calcium carbonate are met.

Description

Technical Field

[0001] The present invention relates to the technical field of calcium carbonate preparation, and in particular to a method for controllably preparing calcium carbonate in a power plant flue gas-ammonia-calcium system. Background Art

[0002] Calcium carbonate, as an important chemical raw material, has a wide range of applications in industrial production, such as being used to manufacture building materials, plastics, rubbers, coatings, etc. Traditional methods for preparing calcium carbonate often rely on pure chemical reagents or specific ore raw materials, and have problems such as high costs and strong resource dependence.

[0003] Power plant flue gas contains a large amount of carbon dioxide (CO 2 ₂). If these carbon dioxides can be effectively captured and utilized to prepare calcium carbonate, it can not only realize the resource utilization of waste gas and reduce carbon emissions, but also provide a new and sustainable path for the preparation of calcium carbonate. Using an ammonia-calcium chloride-ammonium chloride system as the absorbent to mineralize CO 2 ₂ in flue gas to prepare calcium carbonate is a newly emerging method recently. However, the ammonium ions (NH 4 + ₄⁺) in the system will interact with the functional groups on the surface of calcium carbonate. This interaction may change the surface charge distribution and surface energy of calcium carbonate particles. When the charge distribution on the particle surface is uneven or the surface energy decreases, the interactions such as electrostatic attraction or van der Waals force between particles will increase, resulting in agglomeration between particles and making it difficult to meet the precise control requirements for product particle size, crystal form and other indicators. Therefore, there is an urgent need for a method for controllably preparing calcium carbonate using power plant flue gas in an ammonia-calcium system.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for controllably preparing calcium carbonate in a power plant flue gas-ammonia-calcium system, which can effectively control the calcium carbonate preparation process in the power plant flue gas-ammonia-calcium system to obtain high-quality calcium carbonate products.

[0006] In the first aspect of the present invention, there is provided a method for controllably preparing calcium carbonate in a power plant flue gas-ammonia-calcium system, including the following steps:

[0007] S1. Place the mixed solution of ammonia water, calcium chloride and ammonium chloride in a reaction vessel, and adjust the pH value range of the mixed solution to 9-10;

[0008] S2. After the power plant flue gas is pretreated by dust removal, desulfurization and denitrification and cooled down, it is introduced into the bottom of the reaction vessel;

[0009] S3. During the continuous introduction of power plant flue gas into the reaction vessel, slowly add the calcium carbonate product control agent solution, which includes chitosan, dimethylaminoethyl polymethacrylate, D-sodium gluconate, L-glutamic acid, and water, and fully react;

[0010] S4. After the reaction ends, perform solid-liquid separation on the generated calcium carbonate slurry, and calcite-type calcium carbonate is obtained after drying.

[0011] In the calcium carbonate product control agent solution, the specific functions of each component are as follows:

[0012] Chitosan can selectively adsorb on different crystal planes of calcium carbonate crystals, hinder the growth of some crystal planes, thereby changing the relative growth rate of each crystal plane and controlling the crystal shape. Chitosan can modify the surface of calcium carbonate, improve its dispersibility and adhesion on the fiber surface, and improve the application performance of calcium carbonate as a filler. Chitosan has good biocompatibility, which helps to prepare calcium carbonate composites with biological activity.

[0013] Due to the presence of hydrophilic and hydrophobic groups in its molecular structure, dimethylaminoethyl polymethacrylate can be used as a dispersant for calcium carbonate to improve its dispersion stability in the solution. Dimethylaminoethyl polymethacrylate can also affect the crystal growth habit by selectively adsorbing on specific crystal planes of calcium carbonate crystals, thereby controlling the morphology of calcium carbonate.

[0014] D-sodium gluconate can inhibit the heterogeneous growth of crystals and control the crystal growth direction by adsorbing on specific crystal planes of calcium carbonate crystal nuclei, thereby stabilizing the crystal form of calcium carbonate. D-sodium gluconate can also be used as a dispersant for calcium carbonate to improve its dispersion performance in the solution. During the precipitation process of calcium carbonate, D-sodium gluconate plays a templating role to guide the growth of calcium carbonate crystals and form calcium carbonate particles with a specific morphology.

[0015] L-glutamic acid can affect the nucleation and growth process of calcium carbonate crystals by binding with calcium ions, thereby changing the morphology of calcium carbonate. L-glutamic acid helps to simulate the biomineralization process and helps to prepare calcium carbonate with biological activity.

[0016] Preferably, in step S1, the molar ratio of ammonium ions to calcium ions in the mixed solution of ammonia water, calcium chloride, and ammonium chloride is controlled at 2.0 - 2.6.

[0017] Preferably, in step S1, ammonia water, calcium hydroxide, or hydrochloric acid is used to adjust the pH value of the mixed solution.

[0018] Preferably, in step S2, the concentration of CO 2 in the power plant flue gas is 8 - 15%, and the particulate matter is less than 10 mg / m 3, sulfur dioxide is less than 25 mg / m 3 , nitrogen oxide concentration is less than 50 mg / m 3 .

[0019] Preferably, in step S2, the flue gas from the power plant is cooled to 20 - 30 °C after pretreatment of dust removal, desulfurization, and denitrification.

[0020] Preferably, in step S3, the mass ratio of chitosan, dimethylaminoethyl polymethacrylate, D - sodium gluconate, L - glutamic acid, and water is 1:(0.1 - 0.3):(2 - 2.5):(0.6 - 0.8):(95.4 - 96.3).

[0021] Preferably, in step S3, the calcium carbonate product control agent solution is added at a flow rate of 0.5 - 1.5 ml / min.

[0022] Preferably, in step S4, the solid - liquid separation is carried out by centrifugation, and the drying is carried out by drum drying, and the drying temperature is 100 - 110 °C.

[0023] Preferably, in step S4, the particle size D50 of the calcite - type calcium carbonate is 10 - 20 microns.

[0024] In the second aspect of the present invention, a calcite - type calcium carbonate is provided, which is prepared by the controllable preparation method of calcium carbonate in the above - mentioned power plant flue gas - ammonia - calcium system.

[0025] The present invention has at least the following beneficial effects:

[0026] The technical solution of the present invention provides a calcium hydroxide system different from the traditional calcium carbonate preparation under the condition of low - concentration CO in the power plant flue gas 2 . In the system with ammonia and calcium salt, by precisely configuring the pH value of the mixed solution, reasonably designing the flue gas pretreatment and introduction method, and skillfully using the calcium carbonate product control agent solution, the key links such as nucleation and growth of calcium carbonate can be effectively regulated, so that the properties such as particle size and crystal form of the final product can be accurately controlled according to the expected requirements, greatly improving the stability and consistency of the product quality, and meeting the requirements for high - quality calcium carbonate in different application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0028] Figure 1 Flow chart of the controllable preparation method of calcium carbonate in the power plant flue gas-ammonia-calcium system provided by the present invention;

[0029] Figure 2 XRD spectrum of calcite-type calcium carbonate crystal provided by the present invention. Detailed implementation manners

[0030] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0031] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary implementation manners according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form also includes the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] Embodiment

[0034] As Figure 1 shown, prepare 2 L of a mixed solution of ammonia water, calcium chloride and ammonium chloride (wherein 3.68 g of ammonium chloride, 1.84 mol / l of ammonia, and 6.94 g of calcium chloride), and the molar ratio of ammonium ion to calcium ion is 2.2; place the mixed solution in a bubbling tower mineralization reaction vessel, and adjust the pH value of the solution to 9.5 by ammonia water / hydrochloric acid. Introduce the power plant flue gas that has been pretreated by dust removal, desulfurization, denitrification and other operations and cooled to 25°C into the bottom of the above-mentioned mineralization reaction vessel, and CO in the flue gas 2The concentration is 10%. The flue gas is evenly dispersed in the mixed reaction solution by an aeration head, and the gas velocity is 120 L / h (the decarbonized flue gas enters the subsequent treatment process or is discharged). 0.03 L of a calcium carbonate product control agent solution is prepared, and the mass ratio of chitosan, poly(dimethylaminoethyl methacrylate) (PDMEAMA), D-sodium gluconate, L-glutamic acid, and water is 1:0.2:2:0.7:96.1; during the continuous introduction of the power plant flue gas into the reaction solution, the calcium carbonate product control agent solution is slowly added at a flow rate of 0.5 ml / min to ensure sufficient contact with the reaction substances. The generated calcium carbonate slurry is centrifuged for solid-liquid separation, and after drying at 105 °C, calcite-type calcium carbonate products are obtained. The particle size distribution is shown in Table 1, and the XRD pattern of the calcium carbonate crystal form is as Figure 2 shown.

[0035] Table 1 Particle Size Distribution Table of Calcium Carbonate

[0036] Cumulative particle size distribution D10 D50 D90 D97 Particle size / µm 6.58 14.53 25.01 26.43

[0037] Comparative Example 1

[0038] This comparative example is basically the same as the example, except that: in this comparative example, the calcium carbonate product control agent solution is not added.

[0039] The results show that: compared with the example, the calcium carbonate obtained in this comparative example is inferior in terms of particle size, crystal form, etc., and the overall quality of the product is lower.

[0040] Comparative Example 2

[0041] This comparative example is basically the same as the example, except that: in this comparative example, the calcium carbonate product control agent solution includes: chitosan, poly(dimethylaminoethyl methacrylate), D-sodium gluconate, and water.

[0042] The results show that: compared with the example, the quality of the calcium carbonate obtained in this comparative example is slightly lower than that of the calcium carbonate in the example in terms of particle size, crystal form, etc.; compared with Comparative Example 1, the quality of the calcium carbonate obtained in this comparative example has been improved in terms of particle size, crystal form, etc.

[0043] Comparative Example 3

[0044] This comparative example is basically the same as the example, except that: in this comparative example, the calcium carbonate product control agent solution includes: the calcium carbonate product control agent solution includes: chitosan, poly(dimethylaminoethyl methacrylate), L-glutamic acid, and water.

[0045] The results show that: compared with the example, the quality of the calcium carbonate obtained in this comparative example is slightly lower than that of the calcium carbonate in the example in terms of particle size, crystal form, etc.; compared with Comparative Example 1, the quality of the calcium carbonate obtained in this comparative example has been improved in terms of particle size, crystal form, etc.

[0046] Comparative Example 4

[0047] This comparative example is basically the same as the example, except that: in this comparative example, the calcium carbonate product control agent solution includes: the calcium carbonate product control agent solution includes: chitosan, D-sodium gluconate, L-glutamic acid and water.

[0048] The results show that: compared with the example, the quality of the calcium carbonate obtained in this comparative example is slightly lower than that of the calcium carbonate in the example in terms of particle size, crystal form, etc.; compared with Comparative Example 1, the quality of the calcium carbonate obtained in this comparative example has been improved in terms of particle size, crystal form, etc.

[0049] Comparative Example 5

[0050] This comparative example is basically the same as the example, except that: in this comparative example, the calcium carbonate product control agent solution includes: the calcium carbonate product control agent solution includes: dimethylaminoethyl polymethacrylate, D-sodium gluconate, L-glutamic acid and water.

[0051] The results show that: compared with the example, the quality of the calcium carbonate obtained in this comparative example is slightly lower than that of the calcium carbonate in the example in terms of particle size, crystal form, etc.; compared with Comparative Example 1, the quality of the calcium carbonate obtained in this comparative example has been improved in terms of particle size, crystal form, etc.

[0052] In summary, the present invention provides a calcium hydroxide system different from the traditional calcium carbonate preparation under the condition of low-concentration CO in power plant flue gas 2 Under the condition of, in a system with ammonia and calcium salt, by precisely configuring the pH value of the mixed solution, reasonably designing the flue gas pretreatment and inlet mode, and skillfully using the calcium carbonate product control agent solution, the key links such as nucleation and growth of calcium carbonate can be effectively regulated, so that the properties such as particle size and crystal form of the final product can be accurately controlled according to the expected requirements, greatly improving the stability and consistency of the product quality and meeting the requirements for high-quality calcium carbonate in different application scenarios.

[0053] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A controllable preparation method of calcium carbonate in a power plant flue gas-ammonia-calcium system, characterized in that: The following steps are involved: S1, placing a mixed solution of ammonia water, calcium chloride and ammonium chloride in a reaction vessel, and adjusting the pH value of the mixed solution to a range of 9-10; S2, the flue gas from the power plant is cooled after being pre-treated with dust removal, desulfurization and denitrification, and then introduced into the bottom of the reaction vessel; S3. While the flue gas from the power plant is continuously introduced into the reaction vessel, a calcium carbonate product control agent solution is slowly added, wherein the calcium carbonate product control agent solution comprises chitosan, polydimethylaminoethyl methacrylate, sodium D-gluconate, L-glutamic acid and water, and the reaction is fully carried out; S4. After the reaction is completed, the generated calcium carbonate slurry is subjected to solid-liquid separation and dried to obtain calcite calcium carbonate.

2. The controllable preparation method of calcium carbonate in the power plant flue gas-ammonia-calcium system according to claim 1, characterized in that: In step S1, the molar ratio of ammonium ions to calcium ions in the mixed solution of ammonia water, calcium chloride and ammonium chloride is controlled to be 2.0 to 2.

6.

3. The controllable preparation method of calcium carbonate in the power plant flue gas-ammonia-calcium system according to claim 1, characterized in that: In step S1, ammonia water, calcium hydroxide or hydrochloric acid is used to adjust the pH value of the mixed solution.

4. The controllable preparation method of calcium carbonate in the power plant flue gas-ammonia-calcium system according to claim 1, characterized in that: In step S2, the concentration of CO2 in the flue gas of the power plant is 8-15%, and the particulate matter is less than 10 mg / m 3 , sulfur dioxide is less than 25mg / m 3 , nitrogen oxide concentration is less than 50mg / m 3 .

5. The controllable preparation method of calcium carbonate in the power plant flue gas-ammonia-calcium system according to claim 1, characterized in that: In step S2, the flue gas from the power plant is cooled to 20-30°C after being pre-treated with dust removal, desulfurization and denitrification.

6. The controllable preparation method of calcium carbonate in the power plant flue gas-ammonia-calcium system according to claim 1, characterized in that: In step S3, the mass ratio of chitosan, polydimethylaminoethyl methacrylate, sodium D-gluconate, L-glutamic acid and water is 1: (0.1-0.3): (2-2.5): (0.6-0.8): (95.4-96.3).

7. The controllable preparation method of calcium carbonate in the power plant flue gas-ammonia-calcium system according to claim 1, characterized in that: In step S3, the calcium carbonate product control agent solution is added at a flow rate of 0.5-1.5 ml / min.

8. The controllable preparation method of calcium carbonate in the power plant flue gas-ammonia-calcium system according to claim 1, characterized in that: In step S4, the solid-liquid separation is carried out by centrifugation, and the drying is carried out by drum drying at a drying temperature of 100-110°C.

9. The controllable preparation method of calcium carbonate in the power plant flue gas-ammonia-calcium system according to claim 1, characterized in that: In step S4, the particle size D50 of the calcite calcium carbonate is between 10 and 20 microns.

10. A calcite-type calcium carbonate, characterized in that: The calcium carbonate is prepared by the controllable preparation method of calcium carbonate in the power plant flue gas-ammonia-calcium system described in any one of claims 1 to 9.

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