High-carbonized active carbon-sequestration cementitious material, and preparation method and application thereof

Abstract

The application discloses a kind of high carbonization active carbon fixation cementing materials, the mineral composition of the cementing material contains: 2CaO·SiO2 20-50wt%, 3CaO·CaF2·2SiO2 20-60wt%, 3CaO·2SiO2 0-20wt% by mass percentage;Preparation method includes low-grade fluorite ore and dry red mud are mixed, grinding, to obtain raw meal powder;The raw meal powder is pressed into tablets, to obtain raw material tablets;The raw material tablets are calcined;Cool to room temperature, the high carbonization active carbon fixation cementing material is obtained;The raw material of the application is all used low-grade ore and industrial solid waste, can large-scale use low-grade ore and industrial solid waste, alleviate the problem of tight mineral resources, greatly reduce the production cost of enterprise;The calcination temperature of the obtained high carbonization active carbon fixation cementing material is 900-1100 DEG C, compared with the sintering temperature 1450 DEG C of traditional Portland cement clinker, is reduced by 550-350 DEG C, significantly reduces the amount of fossil fuel, reduces CO2 emission in production process.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a carbon-fixing cementitious material, its preparation method, and its application. Background Technology

[0002] Cement, as a crucial component of the building materials and construction industry, sees its annual production volume steadily increasing. The main mineral components of cement are C3S, C2S, C3A, and C4AF. Due to its unique mineral composition, the production of each ton of cement clinker typically requires the consumption of a large amount of limestone (~1.25t) and emits a substantial amount of CO2 (~0.85t). The main sources of CO2 emissions are the decomposition of raw materials (~60%), the combustion of fossil fuels (~30%), and electricity consumption during grinding and transportation (~10%). This production characteristic leads to rapid resource depletion and massive greenhouse gas emissions.

[0003] Industrial solid waste refers to solid waste generated during industrial production activities. With the rapid pace of urbanization and modernization, the demand for materials such as metals and building materials is increasing year by year, leading to a corresponding increase in the discharge of industrial solid waste. The large-scale accumulation of industrial solid waste pollutes water bodies and air, seriously threatening the human living environment. However, industrial solid waste has a chemical composition similar to that of carbon-fixing cementitious materials, possessing the potential to be used as raw materials for their preparation. Therefore, the efficient and high-value utilization of industrial solid waste in the production of carbon-fixing cementitious materials is of great significance for green, low-carbon, and sustainable development.

[0004] Carbon-fixed cementitious materials, as an emerging building material, have attracted worldwide attention due to their low calcination temperature (~1200℃), low calcium resource consumption, low CO2 emissions, and ability to absorb large amounts of CO2. By utilizing the ability of silicate minerals to react with CO2, carbon-fixed cementitious materials can form stable carbonate and silica gels. These carbonized products bind together to form a hardened carbonized body, exhibiting excellent mechanical properties. However, the current preparation of carbon-fixed cementitious materials mainly relies on the calcination of siliceous raw materials such as limestone and sandstone. Therefore, further mitigating resource consumption and reducing CO2 emissions has become a crucial challenge. Summary of the Invention

[0005] The purpose of this invention is to provide a high-carbonization active solid carbon cementitious material prepared by low-temperature calcination, its preparation method and application, and to make resource utilization of industrial solid waste and low-grade ore.

[0006] To achieve the above objectives, the following technical solution is adopted: A highly carbonized active solid carbon cementitious material, the mineral composition of which, by mass percentage, contains: 20-50 wt% 2CaO·SiO2, 20-60 wt% 3CaO·CaF2·2SiO2, and 0-20 wt% 3CaO·2SiO2.

[0007] In the optimized scheme, the mineral composition by mass percentage is: 2CaO·SiO2 20-43wt%, 3CaO·CaF2·2SiO2 24-53wt%, and 3CaO·2SiO2 4-16wt%.

[0008] The present invention also provides a method for preparing the aforementioned highly carbonized active solid carbon cementitious material, comprising the following steps: (1) Mix low-grade fluorite ore and dry red mud, grind them to obtain raw material powder; (2) The raw material powder is compressed into tablets to obtain raw material tablets; (3) Calcining the raw material sheets; (4) Cool to room temperature to obtain the highly carbonized active solid carbon cementitious material.

[0009] According to the above scheme, the content of CaF2 in the low-grade fluorite ore is 10wt%-35wt%, and the content of CaO is 20wt%-45wt%.

[0010] According to the above scheme, the SiO2 content in the dried red mud is 10wt%-25wt%.

[0011] According to the above scheme, the low-grade fluorite ore and dried red mud in step (1) are calculated by weight as follows: 30-50 parts of low-grade fluorite ore and 70-50 parts of dried red mud.

[0012] According to the above scheme, the particle size of the raw material powder in step (1) is ≤75μm.

[0013] According to the above scheme, the calcination temperature in step (3) is 900-1100℃ and the calcination time is 1-2 h.

[0014] According to the above scheme, the cooling rate in step (4) is ≥500℃ / min.

[0015] The present invention also provides the application of the above-mentioned highly carbonized active carbon-fixing cementitious material in CO2 fixation.

[0016] The application of the above-mentioned highly carbonized active carbon-fixing cementitious materials in CO2 fixation includes the following steps: (1) Mix the high carbonization active solid carbon cementitious material with water evenly; (2) Press and mold to obtain a molded part; (3) Place the molded part in a CO2 atmosphere for carbonization to obtain a carbonized product.

[0017] Fluorite is the main active mineral component in fluorite deposits, but high-fluorite-content fluorite deposits are scarce, with the majority being low-grade. Low-grade fluorite deposits are often associated with other minerals, including quartz and limestone. The low fluorite content necessitates screening processes, significantly increasing ore utilization costs. This invention is designed specifically for limestone-type low-grade fluorite deposits, where the main mineral components are fluorite and limestone. Since the chemical composition of lanthanum requires a small amount of fluorite, it closely matches the chemical composition of low-grade fluorite deposits, thus enabling large-scale resource utilization of these deposits.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Carbonized products prepared using the high carbonization activity solid carbon cementing material of the present invention have high early carbonization strength, continuous growth in later strength, and large carbon fixation capacity. They can be widely used in outdoor building products, craft products and precast engineering components.

[0019] (2) The raw material powder used to prepare the high carbonization active solid carbon cementitious material of the present invention uses all low-grade ore and industrial solid waste, which can make large-scale use of low-grade ore and industrial solid waste, alleviate the problem of ore resource shortage, and greatly reduce the production cost of enterprises.

[0020] (3) The high carbonization active solid carbon cementitious material of the present invention has a calcination temperature of 900-1100℃, which is 550-350℃ lower than the calcination temperature of 1450℃ of traditional silicate cement clinker, significantly reducing the amount of fossil fuel used and reducing CO2 emissions during the production process.

[0021] (4) The emissions of polluting gases such as carbon dioxide and nitrogen oxides during the production of the high carbonization active solid carbon cement material of the present invention are reduced by more than 40% compared with the production of traditional silicate cement, and it can also absorb and solidify about 15% of carbon dioxide during use. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0023] The low-grade fluorite ore and red mud used in the specific implementation method were obtained from the Siziwang Banner mining area in Inner Mongolia and Jiaozuo, Henan Province, respectively. The chemical composition of the raw materials is shown in Table 1 below: Table 1: Chemical composition of raw materials (wt.%)

[0024] Example 1 The preparation method of the highly carbonized active solid carbon cementitious material in this embodiment includes the following steps: (1) Mix 50 parts of low-grade fluorite ore and 50 parts of red mud thoroughly and grind them to obtain raw material powder (particle size of raw material powder ≤ 75 μm). (2) Weigh a certain amount of raw material powder and put it into the mold. Press it under a pressure of 6 MPa to obtain a raw material sheet with a diameter of 30 mm and a height of 10 mm.

[0025] (3) Calcine the raw material sheets obtained in step (2) at 1000℃ for 2 h; (4) After calcination, the furnace is cooled to room temperature to obtain the high carbonization active solid carbon cementitious material of this embodiment.

[0026] Example 2 The preparation method of the highly carbonized active solid carbon cementitious material in this embodiment includes the following steps: (1) Mix 40 parts of low-grade fluorite ore and 60 parts of red mud thoroughly and grind them to obtain raw material powder (particle size of raw material powder ≤ 75 μm). (2) Weigh a certain amount of raw material powder and put it into the mold. Press it under a pressure of 6 MPa to obtain a raw material sheet with a diameter of 30 mm and a height of 10 mm.

[0027] (3) Calcine the raw material sheets obtained in step (2) at 1000℃ for 2 h; (4) After calcination, the furnace is cooled to room temperature to obtain the high carbonization active solid carbon cementitious material of this embodiment.

[0028] Example 3 The preparation method of the highly carbonized active solid carbon cementitious material in this embodiment includes the following steps: (1) Mix 30 parts of low-grade fluorite ore and 70 parts of red mud thoroughly and grind them to obtain raw material powder (particle size of raw material powder ≤ 75 μm). (2) Weigh a certain amount of raw material powder and put it into the mold. Press it under a pressure of 6 MPa to obtain a raw material sheet with a diameter of 30 mm and a height of 10 mm.

[0029] (3) Calcine the raw material sheets obtained in step (2) at 1000℃ for 2 h; (4) After calcination, the furnace is cooled to room temperature to obtain the high carbonization active solid carbon cementitious material of this embodiment.

[0030] Example 4 The preparation method of the highly carbonized active solid carbon cementitious material in this embodiment includes the following steps: (1) Mix 40 parts of low-grade fluorite ore and 60 parts of red mud thoroughly and grind them to obtain raw material powder (particle size of raw material powder ≤ 75 μm). (2) Weigh a certain amount of raw material powder and put it into the mold. Press it under a pressure of 6 MPa to obtain a raw material sheet with a diameter of 30 mm and a height of 10 mm.

[0031] (3) Calcine the raw material sheets obtained after step (2) at 900℃ for 2 h; (4) After calcination, the furnace is cooled to room temperature to obtain the high carbonization active solid carbon cementitious material of this embodiment.

[0032] Example 5 The preparation method of the highly carbonized active solid carbon cementitious material in this embodiment includes the following steps: (1) Mix 40 parts of low-grade fluorite ore and 60 parts of red mud thoroughly and grind them to obtain raw material powder (particle size of raw material powder ≤ 75 μm). (2) Weigh a certain amount of raw material powder and put it into the mold. Press it under a pressure of 6 MPa to obtain a raw material sheet with a diameter of 30 mm and a height of 10 mm.

[0033] (3) Calcine the raw material sheets obtained in step (2) at 1100℃ for 2 h; (4) After calcination, the furnace is cooled to room temperature to obtain the high carbonization active solid carbon cementitious material of this embodiment.

[0034] Comparative Example 1 The only difference between this comparative example and Example 1 is that the mass fractions of low-grade fluorite ore and red mud in step (1) are 20 parts and 80 parts, respectively; the rest are the same as in Example 1.

[0035] Comparative Example 2 The only difference between this comparative example and Example 1 is that the mass fractions of low-grade fluorite ore and red mud in step (1) are 60 parts and 40 parts, respectively; the rest are the same as in Example 1.

[0036] Comparative Example 3 The only difference between this comparative example and Example 4 is that the calcination temperature is 800℃; all other aspects are the same as in Example 4.

[0037] Comparative Example 4 The only difference between this comparative example and Example 4 is that the calcination temperature is 1200℃; all other aspects are the same as in Example 4.

[0038] Application Examples The carbon-fixing cementitious materials obtained in the above examples and comparative examples were applied to the preparation of carbonized products: (1) The highly carbonized active solid carbon cementitious material is mixed evenly with 10% water to obtain a wet mixture; (2) Place the wet mixture in a 20×20×50mm slab. 3 In the mold, it is pressed under a pressure of 10MPa to obtain a 20×20×20mm shape. 3 The sample; (3) The sample was placed in a carbonization kettle and carbonized for 24 hours to obtain a carbonized product, wherein the carbonization pressure was 0.5 MPa and the carbonization temperature was 25℃.

[0039] Phase analysis was performed on the carbon-fixed cementitious materials obtained in the comparative examples and embodiments. The carbon-fixed cementitious materials were ground until all powder could pass through a 200-mesh sieve, and the resulting powder was subjected to XRD testing. The tests were conducted at 40 kV and 200 mA. The test range was 10-70°, the scan rate was 10° / min, and the Rietveld full-spectrum fitting method was used for quantitative analysis.

[0040] Carbon fixation content was analyzed in the carbonized products obtained in the comparative examples and embodiments. All carbonized products were ground until all powder could pass through a 200-mesh sieve, and approximately 20 mg of powder was weighed for TGA testing. The test range was 50-1000℃, with a heating rate of 10℃ / min. The carbon fixation content was calculated as follows:

[0041] Among them, w 400℃ w is the weight of the sample at 400℃. 850℃ This is the weight of the sample at 850℃.

[0042] The compressive strength of the carbonized products obtained in the comparative examples and embodiments was tested using YAW. The compressive strength was tested using a 300 / 20 microcomputer-controlled compression testing machine at a loading rate of 1 mm / min. The average compressive strength of three specimens was calculated. Examples 1-6 were subjected to XRD, thermogravimetric analysis, and mechanical property tests. The test results are shown in Table 2.

[0043] Table 2 Performance test results of highly carbonized active solid carbon cementitious materials

[0044] XRD, thermogravimetric analysis, and mechanical property tests were performed on comparative examples 1-5, and the test results are shown in Table 3.

[0045] Table 3 Performance test results of highly carbonized active carbon-fixing cementitious materials

[0046] Table 2 shows that red mud and low-grade fluorite ore can react at suitable temperatures to form lanceolate (3CaO·CaF2·2SiO2), dicalcium silicate, and tricalcium disilicate. The presence of fluorite in low-grade fluorite ore can significantly reduce the calcination temperature of highly carbonized active carbon-fixing cementitious materials. The ratio of red mud to low-grade fluorite ore significantly affects the mineral composition of highly carbonized active carbon-fixing cementitious materials. With the increase of the proportion of red mud, the content of calcium silicate minerals in highly carbonized active carbon-fixing cementitious materials gradually increases, while the content of lanceolate decreases. Different minerals exhibit obvious differences in carbonization activity; with the increase of the proportion of calcium silicate minerals, the carbon fixation capacity and mechanical properties of the samples increase.

[0047] Table 3 shows that the proportion of raw materials significantly affects the mineral composition of highly carbonized active carbon-fixing cementitious materials. When the red mud content is high, the fluorite content in the raw meal is low, making it difficult to achieve the low calcination temperature characteristic of highly carbonized active carbon-fixing cementitious materials. Conversely, when the red mud content is low, it cannot provide sufficient SiO2 for the highly carbonized active carbon-fixing cementitious materials, making it difficult to form silicate minerals. On the other hand, a lower calcination temperature makes it difficult for silicate minerals to form, while a higher calcination temperature will cause the clinker to melt, harming production.

[0048] In summary, within the scope defined by this invention, using red mud and low-grade fluorite ore as raw materials, it is possible to calcine highly carbonized, active solid carbon cementitious materials mainly composed of lanceolate, dicalcium silicate, and tricalcium disilicate minerals. Furthermore, the carbonized products exhibit high strength and can be used directly without additional curing. This invention enables large-scale utilization of red mud and low-grade fluorite ore, alleviating current demand for calcium and silicate resources. Simultaneously, its lower calcination temperature, compared to the traditional silicate cement calcination process, reduces energy consumption and CO2 emissions.

Claims

1. A highly carbonized active solidified carbon cementitious material, characterized in that... The mineral composition of the cementitious material, by mass percentage, contains: 20-50 wt% 2CaO·SiO2, 20-60 wt% 3CaO·CaF2·2SiO2, and 0-20 wt% 3CaO·2SiO2.

2. A highly carbonized active solidified carbon cementitious material, characterized in that... The mineral composition of the cementitious material, by mass percentage, contains: 20-43 wt% 2CaO·SiO2, 24-53 wt% 3CaO·CaF2·2SiO2, and 4-16 wt% 3CaO·2SiO2.

3. The method for preparing the highly carbonized active solid carbon cementitious material according to claim 1 or 2, characterized in that... Includes the following steps: (1) Mix low-grade fluorite ore and dry red mud, grind them to obtain raw material powder; (2) The raw material powder is compressed into tablets to obtain raw material tablets; (3) Calcining the raw material sheets; (4) Cool to room temperature to obtain the highly carbonized active solid carbon cementitious material.

4. The preparation method of the highly carbonized active solid carbon cementitious material as described in claim 3, characterized in that... The low-grade fluorite ore contains 10wt%-35wt% CaF2 and 20wt%-45wt% CaO.

5. The preparation method of the highly carbonized active solid carbon cementitious material as described in claim 3, characterized in that... The SiO2 content in the dried red mud is 10wt%-25wt%.

6. The preparation method of the highly carbonized active solid carbon cementitious material as described in claim 3, characterized in that... In step (1), the low-grade fluorite ore and dried red mud are in the following weight parts: 30-50 parts of low-grade fluorite ore and 70-50 parts of dried red mud.

7. The preparation method of the highly carbonized active solid carbon cementitious material as described in claim 3, characterized in that... The particle size of the raw material powder mentioned in step (1) is ≤75μm.

8. The preparation method of the highly carbonized active solid carbon cementitious material as described in claim 3, characterized in that... In step (3), the calcination temperature is 900-1100℃ and the calcination time is 1-2 h.

9. The preparation method of the highly carbonized active solid carbon cementitious material as described in claim 3, characterized in that... The cooling rate in step (4) is ≥500℃ / min.

10. The application of the highly carbonized active carbon-fixing cementitious material according to claim 1 or 2 in CO2 fixation.

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