Method for preparing low-carbon cement by using inactivated solid waste-based calcium-based CO2 adsorbent

Abstract

The invention belongs to the technical field of cement building materials, and discloses a method for preparing low-carbon cement by using an inactivated solid waste-based calcium-based CO2 adsorbent, which comprises the following steps: S1, determining the component requirement of a target cement clinker, weighing a certain amount of inactivated solid waste-based calcium-based CO2 adsorbent, and calculating the ratio of each raw material to obtain a raw material; s2, mixing, crushing and drying the raw materials obtained in the step S1 to obtain a raw material; s3, calcining and quenching the raw material obtained in the step S2 to obtain clinker; s4, after cooling is completed, the clinker obtained in the step S3, common clinker and an admixture are mixed, crushing and grinding are conducted, and finally the low-carbon cement is obtained. According to the method, traditional solid waste with unstable chemical components is replaced with the inactivated solid waste-based calcium-based CO2 adsorbent with stable chemical components, so that the raw material composition certainty in cement raw material proportioning is realized, the stability and controllability of low-carbon cement production are favorably improved, and large-scale and continuous production is facilitated.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of cement building materials, and more specifically relates to a method for preparing low-carbon cement from deactivated solid waste-based calcium-based CO2 adsorbent. BACKGROUND Cement, as an important building material, is widely used in the fields of construction, road, bridge, etc., but the carbon dioxide emissions in its production process have caused serious negative impacts on the environment. In order to address this challenge, the cement industry has taken some measures, especially in the aspect of raw material substitution, and has achieved preliminary results. Specifically, by using solid waste such as fly ash, slag, carbide slag, etc. to replace traditional lime and clay raw materials, the recycling of raw materials has been successfully achieved, and this technology has shown certain advantages in saving natural resources and reducing CO2 emissions. The theoretical and technical basis is relatively mature, but there are still some problems. Traditional solid waste is derived from other industrial production processes, and its composition varies greatly. The solid waste produced by different industrial enterprises and different products has different chemical compositions, which makes the effective ingredient content of the solid waste as cement raw material unstable, affecting the continuity and stability of cement production. In addition, the current procurement of solid waste raw materials is mostly in a point-to-point mode, that is, cement plants cooperate with specific industrial enterprises to obtain solid waste raw materials, which makes it difficult to achieve large-scale application and promotion.

[0002] Under this background, the potential of some high-calcium solid waste has begun to attract more attention. In addition to being directly used as cement raw materials, solid waste with high calcium content can also be used to prepare calcium-based CO2 adsorbent for carbon capture and storage (CCUS) in cement plants. This technology not only effectively reduces CO2 emissions in the cement production process, but also absorbs CO2 through adsorption technology, thereby reducing overall carbon emissions. However, as the use of solid waste-based calcium-based adsorbent increases, how to effectively dispose of the deactivated solid waste-based calcium-based adsorbent remains an unsolved problem. The deactivated solid waste-based calcium-based adsorbent has similar composition to cement raw materials, and after a period of calcium recycling and chemical composition adjustment, its microstructure is reconstructed and the components tend to be uniform, which makes the deactivated solid waste-based adsorbent can be used again as raw materials for cement production, and has high resource utilization value. Although "recycling deactivated adsorbent for cement production" is technically feasible and has great potential in emission reduction, there is still a lack of systematic disposal and recycling schemes for this process. This bottleneck is limiting the application of this technology in large-scale cement production.

[0003] Therefore, in view of the above problems, the present application proposes a low-carbon cement production method based on deactivated solid waste-based calcium-based CO2 adsorbent, aiming to realize the resource utilization of deactivated solid waste-based calcium-based CO2 adsorbent, meet the demand of cement manufacturing industry for high-quality solid waste raw material substitution, and provide an innovative solution for carbon reduction in the cement industry. SUMMARY

[0004] In order to overcome the above defects of the prior art or improve the technical problems, the present application provides a method for preparing low-carbon cement by using deactivated solid waste-based calcium-based CO2 adsorbent, which aims to introduce the deactivated solid waste-based calcium-based CO2 adsorbent into the cement raw material batching, and solves the technical problems of disposing the deactivated solid waste-based calcium-based CO2 adsorbent and producing low-carbon cement without generating additional processes.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a method for preparing low-carbon cement by using deactivated solid waste-based calcium-based CO2 adsorbent is provided, which comprises the following steps: S1: determining the target cement clinker composition requirements, weighing a certain amount of deactivated solid waste-based calcium-based CO2 adsorbent, adding lime material, clay material and corrective agent to the deactivated solid waste-based calcium-based CO2 adsorbent, calculating the ratio of each raw material, and obtaining the raw material; S2: mixing, crushing and drying the raw material obtained in step S1 to obtain the raw material; S3: calcining and quenching the raw material obtained in step S2 to obtain the clinker; S4: after cooling, uniformly mixing the clinker obtained in step S3 with ordinary clinker and blending agent, and crushing and grinding to obtain low-carbon cement; the composition of the ordinary clinker includes 50-70% tricalcium silicate, 15-30% dicalcium silicate, 5-10% tricalcium aluminate and 5-15% tetracalcium aluminoferrite.

[0006] Preferably, in step S1, the lime material is selected as calcium carbonate, the clay material is selected as silicon dioxide, and the corrective agent is selected as aluminum oxide, iron oxide and magnesium oxide, and the mixture composition ratio is: calcium carbonate 66%, silicon dioxide 22.4%, aluminum oxide 5.8%, iron oxide 3.8% and magnesium oxide 2%.

[0007] Preferably, in step S2, the raw material is crushed and powdered by a crusher so that the raw material can smoothly pass through a 0.1mm sieve, and then is placed in a 150-200℃ furnace for drying for 1.5-2h to obtain the raw material.

[0008] Preferably, in step S3, the calcination method is: placing the raw material into a high-temperature furnace for calcination, heating to 500℃, maintaining for 1-1.5h; heating to 950℃, maintaining for 1-1.5h; heating to 1400℃, maintaining for 1.5-2h.

[0009] Preferably, in step S3, the quenching method is: taking out the clinker before the furnace temperature drops to 1300℃, and cooling by directly blowing with a high-power fan to room temperature within 5-10min.

[0010] Preferably, in step S4, the blending agent is set as one or more of gypsum, blast furnace slag and fly ash.

[0011] In step S4, the material is broken by a crusher, and the particle size of the broken clinker is not greater than 3 mm, and then the ball mill is used for grinding.

[0012] Preferably, in step S4, the rotation speed of the ball mill is 400 r / min, the ball-to-material ratio is 2:1, the ball milling time is 1.5 h, the selected grinding ball diameter is 3 mm and 10 mm, and the ratio of the two is 4:1; after the ball milling is completed, the grinding balls are screened, and the low-carbon cement is collected.

[0013] Overall, compared with the prior art, the method for preparing low-carbon cement from deactivated solid waste-based calcium-based CO2 adsorbent provided by the application mainly has the following beneficial effects: 1. The deactivated solid waste-based calcium-based CO2 adsorbent with stable chemical composition is used to replace the traditional solid waste (such as fly ash, carbide slag, etc.) with unstable chemical composition, so that the raw material composition certainty in the cement raw material batching is realized. This replacement helps to improve the stability and controllability of low-carbon cement production, and facilitates large-scale and continuous production. Compared with the current mode of point-to-point procurement of solid waste raw materials by cement plants and specific industrial enterprises, the deactivated adsorbent with uniform composition has better market circulation ability and large-scale application prospect.

[0014] 2. The application provides an effective deactivated solid waste-based calcium-based CO2 adsorbent disposal scheme, which is perfectly connected with low-carbon cement production, and uses the uniformity of the composition after calcium cycle and chemical composition adjustment to make it as a raw material for cement production, thereby realizing the resource recycling of solid waste, reducing resource waste, and providing an innovative solution for carbon reduction in the cement industry.

[0015] 3. The application does not add any additional process steps in the cement production process, but directly replaces the solid waste raw material with the deactivated solid waste-based calcium-based CO2 adsorbent in the existing raw material preparation link. This way not only simplifies the production process, but also efficiently realizes the disposal and resource utilization of the deactivated solid waste, reduces the production cost, and improves the production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a low-carbon cement production method based on deactivated solid waste-based calcium-based CO2 adsorbent according to the application; Figure 2 is a clinker after calcination according to the application; Figure 3 is a low-carbon cement after grinding according to the application; Figure 4 is the XRD results of examples 1-3 and control example 1 according to the application. DETAILED DESCRIPTION

[0017] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0018] The present application will be further described in detail below with reference to the drawings.

[0019] The following examples will prepare several low-carbon cements with different proportions of inactive solid waste-based calcium-based CO2 adsorbents mixed in raw materials, detect their two key performances of strength and free calcium oxide content, and compare them with the PO42.5 cement produced by replacing raw materials with fly ash on the market, to illustrate the implementation method and implementation effect of the present application. In the following examples, the chemical raw materials are commercially available, and the instruments used are commercially available unless otherwise specified. The operation and detection methods not specifically stated are the standard methods specified in the industry.

[0020] In the following examples, the chemical composition (in terms of oxides) of the inactive solid waste-based calcium-based CO2 adsorbent and the prepared clinker is shown in Table 1.

[0021]

[0022] Example 1 The preparation process of the present application is shown in Figure 1 This example 1 will prepare a low-carbon cement with 5% of raw materials replaced by inactive solid waste-based calcium-based CO2 adsorbent. The total weight of the raw materials is 2881g, of which: inactive solid waste-based calcium-based CO2 adsorbent 100g, limestone 2229g, quartz sand 436g, aluminum oxide 106g, iron oxide 74.5g, and magnesium oxide 35.5g.

[0023] Mix the raw materials, crush them with a crusher for 2 minutes to obtain powdered raw materials. Screen them with a 0.1mm round hole screen, and only a small amount of granular raw materials is retained. Collect the powder under the screen, and then place it in a 200℃ oven for 1.5h to obtain powdered raw materials. Put the raw materials into a high-temperature furnace and follow the set program: heat up to 500℃ for 1h, keep the temperature for 1.5h; heat up to 950℃ for 1h, keep the temperature for 1.5h; heat up to 1400℃ for 1h, keep the temperature for 2h to calcine.

[0024] After calcination is completed, the high-temperature furnace automatically powers off and cools down according to the set program. Before the furnace temperature drops to 1300℃, quickly take out the clinker, which is in a red-hot state at this time. Cool it down to room temperature by blowing it directly with a fan, as shown in Figure 2 The clinker is black and lumpy at this time.

[0025] The clinker is put into a crusher for 3 minutes, at which time the clinker is crushed into black gray powder, and there is a small part of 1-2 mm small pieces. Then, the clinker is put into a ball mill together with the admixture such as slag powder, fly ash, etc. for grinding, the rotation speed of the ball mill is 400 r / min, the ball-material ratio is 2:1, the ball milling time is 1.5 h, the selected grinding balls have a diameter of 3 mm and 10 mm, and the ratio of the two is 4:1. After the ball milling is completed, the grinding balls are screened, and the low-carbon cement is collected, which is in the form of gray fine powder, as shown in Figure 3 .

[0026] The low-carbon cement obtained in Example 1 is detected by XRD mineral phase analysis, which shows that the main mineral phase components are dicalcium silicate and tricalcium silicate. At the same time, the free calcium oxide content, the compressive strength and the flexural strength are detected, and the results are as follows: the free calcium oxide content is 1.38%, the 3d compressive strength is 18.1 MPa, the 28d compressive strength is 49.4 MPa, the 3d flexural strength is 4.5 MPa, and the 28d flexural strength is 8.2 MPa.

[0027] Example 2 The preparation process of the present application is shown in Figure 1 . In this Example 2, the low-carbon cement is prepared by replacing 10% of the raw materials with the deactivated solid waste-based calcium-based CO2 adsorbent. The total weight of the raw materials is 2724 g, of which: the deactivated solid waste-based calcium-based CO2 adsorbent is 200 g, the limestone is 2100 g, the quartz sand is 424 g, the aluminum oxide is 96 g, the iron oxide is 73 g, and the magnesium oxide is 31 g.

[0028] The raw materials are mixed and crushed by a crusher for 2 minutes to obtain a powder-like raw material. The powder-like raw material is screened by a 0.1 mm round hole screen, and only a small amount of granular raw material is screened. The powder under the screen is collected and then placed in a 200℃ oven for 1.5 h to obtain a powder-like raw material. The raw material is placed in a high-temperature furnace and calcined according to the set program: heated to 500℃ for 1 h, kept for 1.5 h; heated to 950℃ for 1 h, kept for 1.5 h; heated to 1400℃ for 1 h, and kept for 2 h.

[0029] After the calcination is completed, the high-temperature furnace is automatically powered off and cooled according to the set program. Before the furnace temperature drops to 1300℃, the clinker is quickly taken out, at which time the clinker is in a red-hot state. The clinker is cooled by a fan blowing directly, and cooled to room temperature after 10 min, as shown in Figure 2 , at which time the clinker is in the form of black gray lumps.

[0030] The clinker is put into a crusher for 3 minutes, at which time the clinker is broken into black gray powder, and there is a small part of 1-2 mm small pieces. Then, the clinker is put into a ball mill together with the admixture such as slag powder, fly ash, etc. for grinding. The rotation speed of the ball mill is 400 r / min, the ball-material ratio is 2:1, the ball milling time is 1.5 h, the selected grinding ball diameter is 3 mm and 10 mm, and the ratio of the two is 4:1. After the ball milling is completed, the grinding balls are screened, and the low-carbon cement is collected.

[0031] The low-carbon cement obtained in Example 2 is detected by XRD mineral phase analysis, which shows that the main mineral phase components are dicalcium silicate and tricalcium silicate. At the same time, the free calcium oxide content, the compressive strength and the flexural strength are detected, and the results are as follows: the free calcium oxide content is 1.43%, the 3d compressive strength is 17.4 MPa, the 28d compressive strength is 48.9 MPa, the 3d flexural strength is 4.2 MPa, and the 28d flexural strength is 7.8 MPa.

[0032] Example 3 The preparation process of the present application is shown in Figure 1 This embodiment 3 will prepare low-carbon cement by replacing 20% of the raw materials with deactivated solid waste-based calcium-based CO2 adsorbent. The total weight of the raw materials is 2411g, including: 400g of deactivated solid waste-based calcium-based CO2 adsorbent, 1843g of limestone, 400g of quartz sand, 76g of aluminum oxide, 70g of iron oxide, and 22g of magnesium oxide.

[0033] The raw materials are mixed and crushed by a crusher for 2 minutes to obtain powder-like raw materials. Only a small amount of granular raw materials is screened. The powder under the screen is collected and then placed in a 200℃ oven for 1.5h to obtain powder-like raw materials. The raw materials are placed in a high-temperature furnace and calcined according to the set program: heated to 500℃ for 1h, kept for 1.5h; heated to 950℃ for 1h, kept for 1.5h; heated to 1400℃ for 1h, kept for 2h.

[0034] After the calcination is completed, the high-temperature furnace is automatically powered off and cooled according to the set program. Before the furnace temperature drops to 1300℃, the clinker is quickly taken out, at which time the clinker is red-hot. It is cooled by a fan blowing directly, and it is cooled to room temperature after 10 minutes, as shown in Figure 2 At this time, the clinker is black and clumpy.

[0035] The clinker is put into a crusher for 3 minutes, at which time the clinker is broken into black gray powder, and there is a small part of 1-2 mm small pieces. Then, the clinker is put into a ball mill together with the admixture such as slag powder, fly ash, etc. for grinding. The rotation speed of the ball mill is 400 r / min, the ball-material ratio is 2:1, the ball milling time is 1.5 h, the selected grinding ball diameter is 3 mm and 10 mm, and the ratio of the two is 4:1. After the ball milling is completed, the grinding balls are screened, and the low-carbon cement is collected.

[0036] The low-carbon cement obtained in Example 3 was detected by XRD mineral phase analysis, which showed that the main mineral phase components were dicalcium silicate and tricalcium silicate. The free calcium oxide content, compressive strength and flexural strength were also detected, and the results were as follows: free calcium oxide content 1.46%, 3d compressive strength 15.6 MPa, 28d compressive strength 43.3 MPa, 3d flexural strength 3.9 MPa, and 28d flexural strength 6.9 MPa.

[0037] Comparative Example 1 In this comparative example 1, a PO42.5 ordinary portland cement produced by mixing fly ash into raw materials on the market was purchased and detected, which was used to compare with Examples 1-3 to reflect the implementation effect of the present application.

[0038] Through detection and comparison with the specification, the main mineral phase components of the ordinary portland cement produced by mixing fly ash into raw materials were dicalcium silicate and tricalcium silicate, the free calcium oxide content was 1.45%, the 3d compressive strength was 17.5 MPa, the 28d compressive strength was 46.7 MPa, the 3d flexural strength was 4.2 MPa, and the 28d flexural strength was 7.6 MPa.

[0039] Table 2 is the detection results of the main properties and performances of the cement in Examples 1-3 and Comparative Example 1, and the corresponding requirements of the national standard for PO42.5 are also attached.

[0040]

[0041] Comparative analysis of Table 2, Figure 4 It can be concluded that the mixing of deactivated solid waste-based calcium-based CO2 adsorbent into raw materials can produce ordinary portland cement, realizing the resource recycling of deactivated adsorbent. When the mixing amount of raw materials is about 10%, the obtained low-carbon cement meets the national standard requirements of PO42.5, and the free calcium oxide content and strength are not weaker than those of the low-carbon cement prepared by fly ash on the market, which has practicality. At the same time, it is not difficult to find from the preparation process of Examples 1-3 that the production of low-carbon cement from deactivated solid waste-based calcium-based CO2 adsorbent does not add new links compared with traditional cement, the chemical composition of the deactivated solid waste-based calcium-based adsorbent is stable, the calculation operation is simple during batching, and it has good industrialization foundation and large-scale application potential. This technology has good applicability, strong practicality, great industrialization potential, can effectively realize the resource recycling of deactivated solid waste-based calcium-based CO2 adsorbent, and at the same time meets the demand of cement manufacturing industry for high-quality solid waste raw material substitution, providing technical support for energy saving and emission reduction of cement building materials.

[0042] Those skilled in the art can easily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of producing low carbon cement from an inactive solid waste based calcium based CO2 sorbent, characterized in that, The method comprises the following steps: S1: determining target cement clinker composition requirements, weighing a certain amount of inactivated solid waste-based calcium-based CO2 adsorbent, adding lime material, clay material and corrective agent thereto, calculating the proportion of each raw material, and obtaining the raw material; S2: mixing, crushing and drying the raw material obtained in step S1 to obtain raw meal; S3: calcining and quenching the raw meal obtained in step S2 to obtain clinker; S4: after cooling, uniformly mixing the clinker obtained in step S3 with ordinary clinker and an admixture, crushing and grinding to obtain low-carbon cement; the composition of the ordinary clinker comprises 50-70% tricalcium silicate, 15-30% dicalcium silicate, 5-10% tricalcium aluminate and 5-15% tetracalcium aluminoferrite.

2. A method of producing low carbon cement from deactivated solid waste based calcium based CO2 sorbents as claimed in claim 1, characterized in that: In step S1, the lime material is selected as calcium carbonate, the clay material is selected as silicon dioxide, and the corrective agent is selected as aluminum oxide, iron oxide and magnesium oxide, and the mixture composition ratio is: calcium carbonate 66%, silicon dioxide 22.4%, aluminum oxide 5.8%, iron oxide 3.8% and magnesium oxide 2%.

3. A method of producing low carbon cement from deactivated solid waste based calcium based CO2 sorbents as claimed in claim 1, wherein: In step S2, the raw material is crushed and powdered by a crusher so that the raw material can smoothly pass through a 0.1mm sieve, and then is placed in a 150-200℃ furnace for drying for 1.5-2h to obtain raw meal.

4. A method of producing low carbon cement from deactivated solid waste based calcium based CO2 sorbents as claimed in claim 1, wherein: In step S3, the calcination method is: placing the raw meal into a high-temperature furnace for calcination, heating to 500℃, maintaining for 1-1.5h; heating to 950℃, maintaining for 1-1.5h; heating to 1400℃, maintaining for 1.5-2h.

5. A method of producing low carbon cement from deactivated solid waste based calcium based CO2 sorbents as claimed in claim 1, wherein: In step S3, the quenching method is: taking out the clinker before the furnace temperature drops to 1300℃, and cooling by directly blowing with a high-power fan to room temperature within 5-10min.

6. A method of making low carbon cement from deactivated solid waste based calcium based CO2 sorbents as claimed in claim 1, characterized in that: In step S4, the admixture is set as one or more of gypsum, blast furnace slag and fly ash.

7. A method of making low carbon cement from deactivated solid waste based calcium based CO2 sorbents as claimed in claim 1, wherein: In step S4, the clinker is crushed by a crusher, and the particle size of the crushed material is not greater than 3mm, and then the material is ground by a ball mill.

8. A method of producing low carbon cement from deactivated solid waste based calcium based CO2 sorbents as claimed in claim 7, wherein: The rotation speed of the ball mill is 400r / min, the ball-to-material ratio is 2:1, the ball milling time is 1.5h, the selected grinding balls have a diameter of 3mm and 10mm, and the ratio of the two is 4:1; after ball milling, the grinding balls are screened, and the low-carbon cement is collected.

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