Negative carbon type cementing material and preparation method thereof

Abstract

The invention discloses a negative carbon type cementing material, which is prepared from the following ingredients in parts by weight: 50 to 130 parts of vaterite type calcium carbonate, 0.2 to 2.5 parts of magnesium salt, 1.0 to 4.5 parts of strontium salt and 10 to 70 parts of water. The preparation method comprises the following steps: dissolving magnesium salt and strontium salt in water to prepare a mixed solution containing magnesium ions and strontium ions; adding vaterite type calcium carbonate into the mixed solution, and stirring for 1-3 minutes until a slurry state appears; the slurry is poured into a mold to be formed, and the negative carbon type cementing material is obtained through heating and curing; the vaterite type calcium carbonate is prepared by resource utilization of soluble calcium resources in industrial by-products, the gelling characteristic is obtained by directional regulation and control of crystal form transformation, and meanwhile, the negative carbon emission effect is achieved by chemical fixation of CO2; compared with a traditional cementing material, the method has the advantages that recycling of industrial by-products is achieved, meanwhile, CO2 is chemically fixed, the negative carbon emission effect is achieved, and contribution is made to environmental protection.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and in particular relates to a negative carbon type cementitious material and a preparation method thereof. Background Art

[0002] Global climate change poses an unprecedented challenge to human society, among which carbon dioxide emissions are one of the main factors leading to global warming. Among the many sources of CO2 emissions, the building materials industry, especially the production of cement-based cementitious materials, has attracted much attention due to its high energy consumption and high CO2 emissions. According to the International Energy Agency (IEA), CO2 emissions in the cement production process account for about 7% of the world's total emissions, and this problem has prompted scientists and engineers to seek more environmentally friendly alternative materials and technologies.

[0003] In order to respond to climate change and reduce carbon emissions, the international community has taken a series of measures. However, existing carbon reduction technologies, such as biological carbon sinks, mineral carbonation, and chemical absorption, although they theoretically provide ways to reduce CO2 emissions, have many limitations in practical applications. These technologies are often accompanied by high costs, technical complexity, uncertainty in long-term stability, and possible negative environmental impacts. In addition, these technologies lack direct economic benefits and are difficult to be widely promoted and applied in the market.

[0004] At the same time, the reuse of industrial by-products provides a new way to reduce environmental pollution and improve resource utilization efficiency. Industrial by-products, such as carbide slag, limestone residue and coal combustion by-products, contain soluble calcium and can theoretically be used as raw materials for cementitious materials. The reuse of these by-products can not only reduce environmental pollution, but also reduce dependence on natural resources. However, the direct use of these by-products faces many challenges in actual operation, including high processing costs, high technical difficulties, low utilization efficiency, and the possible introduction of new environmental risks, such as heavy metal pollution and harmful gas emissions.

[0005] With the growing demand for low-carbon and environmentally friendly materials, the development of a new type of cementitious material that is both environmentally friendly and has excellent performance is of great significance to promoting the green transformation of the building materials industry. Summary of the invention

[0006] The purpose of the present invention is to provide a new type of negative carbon type cementitious material and a preparation method thereof, to make use of soluble calcium resources in industrial by-products to prepare vaterite type calcium carbonate, to obtain cementitious properties by directional control of crystal transformation, and to achieve the effect of negative carbon emission by chemically fixing CO2.

[0007] In order to achieve the above purpose, the technical solutions adopted are as follows:

[0008] A negative carbon type gelling material, the composition of which is as follows by weight:

[0009] 50-130 parts of vaterite-type calcium carbonate, 0.2-2.5 parts of magnesium salt, 1.0-4.5 parts of strontium salt, and 10-70 parts of water.

[0010] According to the above scheme, the magnesium salt is one or a mixture of MgCl2 and Mg(NO3)2.

[0011] According to the above scheme, the strontium salt is one or a mixture of SrCl2 and Sr(NO3)2.

[0012] According to the above scheme, the vaterite type calcium carbonate is prepared in the following manner:

[0013] Utilize NH4 + The solution dissolves the soluble calcium in the industrial by-products, and after filtration, a calcium ion-rich solution is obtained;

[0014] The CO2-containing tail gas is passed into a calcium ion-rich solution by a bubbling method to obtain a suspension containing calcium carbonate precipitate;

[0015] The vaterite-type calcium carbonate was obtained by suction filtration and drying.

[0016] According to the above scheme, the NH4 + The solution is one of NH4Cl, NH4NO3, CH3COONH4 or any mixture thereof, wherein NH4 + The concentration is 0.2~3.8mol / L.

[0017] According to the above scheme, the industrial by-product is carbide slag, wherein the CaO content is ≥60wt%.

[0018] According to the above scheme, the NH4 + The mass ratio of the solution to the industrial by-product is 5-40.

[0019] According to the above scheme, the CO2-containing tail gas is industrial flue gas, in which the CO2 concentration is 10vt% to 37vt%.

[0020] The preparation method of the negative carbon type gelling material comprises the following steps:

[0021] (1) dissolving a magnesium salt and a strontium salt in water to prepare a mixed solution containing magnesium ions and strontium ions;

[0022] (2) adding aragonite calcium carbonate to the mixed solution and stirring for 1 to 3 minutes until a slurry state is formed;

[0023] (3) The slurry is poured into a mold to form the slurry, and then the slurry is cured by heating to obtain a negative carbon type cementitious material.

[0024] According to the above scheme, the curing process includes: steam curing at 50-90°C for 1-8 hours, demoulding, and drying at 90-130°C for 8-20 hours.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention directionally controls the transformation of vaterite to aragonite by adding magnesium salt into the system, and the formed needle-rod-shaped aragonite crystals overlap each other so that the system gains strength. In addition, since strontium carbonate and aragonitic calcium carbonate have highly consistent crystal structures, strontium atoms can occupy some calcium atom sites in aragonite to form solid solution during the crystal transformation process, so that the system gains higher strength.

[0027] Compared with traditional cementitious materials, the present invention not only realizes the resource utilization of industrial by-products, but also achieves the effect of negative carbon emissions through chemical fixation of CO2, thus contributing to environmental protection.

[0028] The preparation method of the present invention not only helps to reduce dependence on natural resources, but also has the potential to be applied in various fields, including building materials, environmental protection, energy storage, etc. due to its environmental friendliness and cost-effectiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 : XRD patterns of each component before and after carbonization.

[0030] Figure 2 : XRD diagram of the test blocks after molding of Examples 1-4.

[0031] Figure 3 : XRD diagram of the test block after comparative molding. DETAILED DESCRIPTION

[0032] The following examples further illustrate the technical solution of the present invention, but are not intended to limit the scope of protection of the present invention.

[0033] A specific embodiment provides a vaterite-type calcium carbonate:

[0034] Vaterite calcium carbonate: Carbide slag is selected as an industrial by-product, and its CaO content is 70.18%. A 2 mol / L NH4Cl solution is prepared, and calcium ions are extracted at a mass ratio of 20. The calcium ion-rich solution obtained after filtration is carbonized by bubbling method, wherein the CO2 concentration is 20%, and the reaction is stopped after the solution pH = 7. The suspension is filtered, and the filter residue is dried to obtain vaterite calcium carbonate. Figure 1 Figure 3 is the XRD diagram of each component before and after carbonization. It can be seen from the figure that after the carbide slag is extracted, the diffraction peak of calcium hydroxide disappears, and only some calcium ions in the calcite have not been dissolved. The calcium carbonate obtained after carbonization is a high-purity vaterite-type calcium carbonate.

[0035] The raw materials and amounts of Examples 1-4 and Comparative Examples are shown in Table 1.

[0036] Table 1

[0037] Vaterite calcium carbonate; g <![CDATA[MgCl2;g]]> <![CDATA[SrCl2;g]]> Water; g Example 1 100 0.2 1.7 43.8 Example 2 100 0.5 1.1 43.4 Example 3 93 0.7 1.8 42.5 Example 4 96 0.8 2.8 41.4 Comparative Example 1 93 0 0 42.8 Comparative Example 2 93 0.7 0 43.0

[0038] The preparation process of the negative carbon type gelling material in the specific embodiment is as follows:

[0039] Dissolve magnesium salt and strontium salt in water to prepare a mixed solution containing magnesium ions and strontium ions; add vaterite-type calcium carbonate into a stirring pot and stir, and add the above mixed solution and stir for 3 minutes until a slurry state appears; pour the slurry into a mold, vibrate and defoam, and form a 20×20×20mm test block. After forming, place it at 90℃ for steam curing for 4 hours and then demold it. Place the test block in a 105℃ oven and dry it for 8 hours before conducting a compressive strength test.

[0040] The strength results of each embodiment and comparative example are shown in Table 2. The phase composition of the test blocks obtained in Examples 1-4 is shown in Figure 2 The XRD pattern of the comparative sample after molding is shown in the attached Figure 3 shown.

[0041] Table 2

[0042]

[0043] It is worth noting that since no Mg was added in Comparative Example 1 2+ , it partially self-powdered after curing and drying, so no strength test was performed, and the XRD results also showed that it was completely composed of calcite ( Figure 3 ), add Mg 2+ After (Comparative Example 2), the product was basically completely transformed into aragonite and the test block showed a certain mechanical strength, which means that Mg 2+ It is indeed a necessary condition for the transformation of vaterite to aragonite. For the embodiment, firstly, the aragonite crystal form accounts for more than 90% of the product, and the strength of the test block can reach 20MPa, which means that only by transforming vaterite to aragonite crystal form can better gelling properties and mechanical strength be obtained; secondly, according to the phase composition, it can be known that ( Figure 2 ), the formation of aragonite depends on the Mg in the system 2+ concentration. Too low a concentration will lead to the formation of calcite in the system. Finally, Sr 2+ The increase in concentration significantly improved the compressive strength of the system, which may be due to the fact that the strontium carbonate and aragonite crystal structures are highly similar, and the Sr atoms produce isostructural substitution to achieve crystal strengthening.

[0044] The above embodiments are only examples for explanation and are not any limitation to the implementation methods. For those skilled in the art, any equivalent modification and substitution of the present invention is also within the protection scope of the claims of the present invention.

Claims

1. A negative carbon type gelling material, characterized in that The composition is calculated by weight as follows: 50-130 parts of vaterite-type calcium carbonate, 0.2-2.5 parts of magnesium salt, 1.0-4.5 parts of strontium salt, and 10-70 parts of water.

2. The negative carbon type gelling material according to claim 1, characterized in that The magnesium salt is one or a mixture of MgCl2 and Mg(NO3)2.

3. The negative carbon type gelling material according to claim 1, characterized in that The strontium salt is one or a mixture of SrCl2 and Sr(NO3)2.

4. The negative carbon type gelling material according to claim 1, characterized in that Described vaterite type calcium carbonate is prepared in the following manner: Utilize NH4 + The solution dissolves the soluble calcium in the industrial by-products, and after filtration, a calcium ion-rich solution is obtained; The CO2-containing tail gas is passed into a calcium ion-rich solution by a bubbling method to obtain a suspension containing calcium carbonate precipitate; The vaterite-type calcium carbonate was obtained by suction filtration and drying.

5. The negative carbon type gelling material according to claim 4, characterized in that The NH4 + The solution is one of NH4Cl, NH4NO3, CH3COONH4 or any mixture thereof, wherein NH4 + The concentration is 0.2~3.8mol / L.

6. The negative carbon type gelling material according to claim 4, characterized in that The industrial by-product is carbide slag, wherein the CaO content is ≥ 60wt%.

7. The negative carbon type gelling material according to claim 4, characterized in that The NH4 + The mass ratio of the solution to the industrial by-product is 5-40.

8. The negative carbon type gelling material according to claim 4, characterized in that The CO2-containing tail gas is industrial flue gas, wherein the CO2 concentration is 10vt% to 37vt%.

9. The method for preparing the negative carbon type gelling material according to claim 1, characterized in that The following steps are involved: (1) dissolving a magnesium salt and a strontium salt in water to prepare a mixed solution containing magnesium ions and strontium ions; (2) adding aragonite calcium carbonate to the mixed solution and stirring for 1 to 3 minutes until a slurry state is formed; (3) The slurry is poured into a mold to form the slurry, and then the slurry is cured by heating to obtain a negative carbon type cementitious material.

10. The method for preparing the negative carbon type gelling material according to claim 9, characterized in that The curing process comprises: steam curing at 50-90° C. for 1-8 hours, demoulding, and drying at 90-130° C. for 8-20 hours.

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