Preparation process of waste incineration fly ash-based low-carbon concrete material

Abstract

The invention discloses a preparation process of a waste incineration fly ash-based low-carbon concrete material, which comprises the following steps: (1) mixing ardealite powder, potassium silicate powder and water, and uniformly stirring to convert phosphoric acid in the ardealite powder into monopotassium phosphate; and drying the obtained slurry, and grinding to obtain the modified gypsum powder. And (2) mixing the modified gypsum powder, waste incineration fly ash, dead burned magnesia powder, diethanol amine, paraffin powder and water, continuously introducing carbon dioxide into the mixture for treatment, drying at the temperature higher than the melting temperature of paraffin to remove moisture, and grinding the obtained solid product to obtain the modified fly ash micro powder. And (3) uniformly mixing cement, coarse aggregate, fine aggregate, modified fly ash micro powder and a water reducing agent serving as raw materials, adding water, and uniformly stirring to obtain the concrete material. According to the technology, solidification of heavy metal elements in the fly ash and carbon capture and solid storage are integrated, and harm caused by utilization of the waste incineration fly ash is effectively reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of concrete material preparation, and particularly relates to a preparation process of a waste incineration fly ash-based low-carbon concrete material. BACKGROUND

[0002] The information disclosed in this Background section is for the purpose of increasing an understanding of the general context of the present application and is not necessarily recognized as prior art.

[0003] Municipal solid waste (MSW) mainly includes food waste, paper, plastic, wood, textiles, etc. With the improvement of living standards, municipal solid waste is increasing. The accumulation of municipal solid waste not only occupies a large amount of land resources, but also easily causes air pollution due to the emission of peculiar smell. Some toxic and harmful substances, pathogens, etc. penetrate into water and soil, causing serious environmental pollution, and then enter the human body through the food chain, affecting the life and health of residents.

[0004] At present, the disposal methods of municipal solid waste mainly include incineration and landfill. Among them, the incineration method has obvious advantages of reduction and energy, and is a widely used waste treatment technology. Municipal solid waste incineration mainly produces bottom ash and fly ash as two by-products, and fly ash accounts for about 3-15wt.% of the total amount. Compared with bottom ash, the concentration of pollutants in fly ash is lower and is widely used as secondary raw materials in the construction field, such as mixing fly ash in concrete materials for waste utilization. However, the fly ash from waste incineration contains certain leachable heavy metals and is classified as hazardous waste. Therefore, it needs to be treated to reduce the secondary harm when used. SUMMARY

[0005] In view of the above problems, the present application provides a preparation process of a waste incineration fly ash-based low-carbon concrete material, which integrates the solidification of heavy metal elements in fly ash and carbon capture, effectively reducing the harm caused by the use of waste incineration fly ash. Specifically, the technical scheme of the present application is as follows.

[0006] A preparation process of a waste incineration fly ash-based low-carbon concrete material, comprising the following steps: (1) mixing phosphogypsum powder, potassium silicate powder and water, and stirring uniformly to convert phosphoric acid in the phosphogypsum powder into potassium dihydrogen phosphate. Then, the obtained slurry is dried and ground to obtain modified gypsum powder.

[0007] (2) the modified gypsum powder, waste incineration fly ash, heavy-burned magnesia powder, diethanolamine, paraffin powder, water are mixed to form a slurry, then carbon dioxide is continuously introduced into the slurry for treatment, after completion, drying is performed above the melting temperature of the paraffin to remove water, and the obtained solid product is ground, thereby obtaining the modified fly ash micro powder.

[0008] (3) cement, coarse aggregate, fine aggregate, the modified fly ash micro powder, and water reducing agent are used as raw materials, and after being uniformly mixed, water is added and uniformly stirred, thereby obtaining a concrete material.

[0009] Further, in step (1), the molar ratio of the potassium silicate powder to phosphoric acid in the phosphogypsum powder is 1.2-1.5:1. Alternatively, the water can only be used to form a slurry of the phosphogypsum powder and the potassium silicate powder.

[0010] Further, in step (1), the drying temperature is 60-70°C, and the time is not less than 30 min.

[0011] Further, in step (1), the obtained powder after grinding is sieved through a 100-300 mesh sieve, thereby obtaining the modified gypsum powder.

[0012] Further, in step (2), the ratio of the modified gypsum powder, waste incineration fly ash, heavy-burned magnesia powder, diethanolamine, paraffin powder, and water is 6-11 parts by weight: 40-55 parts by weight: 1.5-2.5 parts by weight: 0.8-1.4 parts by weight: 3.5-5 parts by weight: 120-130 parts by weight. Alternatively, the fineness of the heavy-burned magnesia powder is not less than 150 mesh.

[0013] Further, in step (2), the introduction rate of the carbon dioxide is 180-230 mL / min, and the continuous introduction time is 30-60 min.

[0014] Further, in step (2), the drying temperature is 2-5°C higher than the temperature at which the paraffin completely melts into a liquid state.

[0015] Further, in step (2), the obtained powder after grinding is sieved through a 200-350 mesh sieve, thereby obtaining the modified fly ash micro powder.

[0016] Further, in step (3), the ratio of the cement, coarse aggregate, fine aggregate, the modified fly ash micro powder, and water reducing agent is 20-32 parts by weight: 50-85 parts by weight: 27-41 parts by weight: 2-4 parts by weight: 0.3-0.65 parts by weight.

[0017] Further, in step (3), the water is added according to a water-cement ratio of 0.38-0.44. In the “water-cement ratio”, “cement” refers to the cement. Any suitable water-cement ratio can also be used according to actual needs.

[0018] Further, in step (3), the water reducing agent includes at least one of polycarboxylic acid water reducing agent, naphthalene water reducing agent, lignin sulfonate water reducing agent, melamine water reducing agent, and the like.

[0019] Compared with the prior art, the technical scheme of the present application has at least the following beneficial effects: The waste incineration fly ash contains water-soluble heavy metal elements, which can cause secondary pollution when directly used as raw materials for concrete materials. Therefore, the waste incineration fly ash cannot be directly utilized. To this end, the present application first modifies phosphogypsum with potassium silicate to form modified gypsum powder containing potassium dihydrogen phosphate and residual potassium silicate. Further, the modified gypsum powder, waste incineration fly ash, heavy-burned magnesium oxide powder, diethanolamine, paraffin powder, and water are used to form a slurry, which is then treated with carbon dioxide. In this process, some heavy metal ions dissolved from the waste incineration fly ash are solidified by the carbonate radical formed by carbon dioxide, integrating the solidification of heavy metal elements and carbon capture. At the same time, the diethanolamine can also absorb carbon dioxide, not only increasing the amount of carbon capture, but also helping to improve the solidification effect of heavy metal ions. As the diethanolamine is gradually consumed, the inhibition of the hydration reaction of potassium dihydrogen phosphate and heavy-burned magnesium oxide powder provided by the diethanolamine to the modified gypsum powder gradually loses its effectiveness. The hydration product formed after the reaction not only can encapsulate and store the solidification product of the heavy metal elements, further increasing the difficulty of re-dissolution, but also helps to improve the strength of the modified fly ash micro-powder obtained. In addition, the residual potassium silicate in the modified gypsum powder also plays a role in capturing carbon dioxide in the above process. The potassium carbonate formed by it can also play a role in activating the waste incineration fly ash and improving its cementitious activity. The activated waste incineration fly ash can undergo a pozzolanic reaction with calcium hydroxide generated by the hydration of the cement component, which helps to improve the mechanical strength of the prepared concrete material. Finally, the product after the above treatment is dried above the melting temperature of the paraffin component. Not only is it convenient to remove the water in it, but also in this process, the paraffin is melted by high temperature and diffuses in the obtained solid product to construct a hydrophobic system. This can further prevent water from entering the solid product and reduce the dissolution of heavy metal elements therein, thereby better encapsulating the heavy metal elements in the waste incineration fly ash and effectively reducing the harm caused by the use of waste incineration fly ash. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explaining the present application. They must not be used as an inappropriate limitation to the present application.

[0021] Figure 1Sample chart of modified fly ash micropowder prepared for the following Examples 1-6.

[0022] Figure 2 Sample chart of compressive strength test for the following Examples 1-4. DETAILED DESCRIPTION

[0023] The application is further described in conjunction with the following examples. It should be understood that these examples are used only for the purpose of illustration and are not intended to limit the scope of the present application. Unless otherwise indicated, the experimental procedures in the following examples were carried out according to conventional conditions or according to the conditions recommended by the manufacturer.

[0024] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art. The reagents or materials used in the present application can be purchased by conventional route, and unless otherwise specified, the reagents or materials used in the present application are used according to the conventional manner or according to the product instruction.

[0025] In addition, any method and material similar or equivalent to those described can be applied to the method of the present application. The technical solutions of the present application are further described in conjunction with the drawings and specific examples of the present application.

[0026] Example 1 A preparation process of a waste incineration fly ash-based low-carbon concrete material, comprising the following steps: (1) According to the molar ratio of potassium silicate powder to phosphoric acid in phosphogypsum powder of 1.5:1, the two are mixed with water and stirred uniformly to form a slurry with a solid content of 45wt.%. Then heated to 60℃ for 1 hour, then the obtained solid is ground, then the obtained powder is sieved through a 200 mesh sieve to obtain modified gypsum powder.

[0027] (2) According to the ratio of 8 parts by weight of the modified gypsum powder, 50 parts by weight of waste incineration fly ash, 2 parts by weight of heavy-burned magnesium oxide powder of 300 mesh, 1.1 parts by weight of diethanolamine, 4 parts by weight of paraffin powder (the temperature at which it completely melts into a liquid is 78℃), and 127 parts by weight of water, the components are mixed and stirred uniformly, then carbon dioxide is continuously introduced into the obtained slurry for 45min (the introduction rate is 210mL / min), and the slurry is continuously stirred during the process. After completion, the slurry is heated to 80℃ to remove water, then the obtained solid product is ground, then the obtained powder is sieved through a 300 mesh sieve to obtain modified fly ash micropowder (as shown in Figure 1 ).

[0028] (3) Each raw material is weighed according to the following proportion: cement (PO 42.5) 26 parts by weight, coarse aggregate 70 parts by weight, fine aggregate 35 parts by weight, modified fly ash micro powder 3.5 parts by weight, and polycarboxylic acid water reducer 0.5 parts by weight. Among them, the coarse aggregate is gravel with a particle size distribution of 5-12 mm, and the fine aggregate is river sand with a particle size distribution of 0.5-2 mm. The above raw materials are dry mixed in a mixer for 3 min, then water is added according to the water-cement ratio of 0.4, and then stirred for 3 min, to obtain the concrete material.

[0029] Performance test: (1) The concrete material prepared in this embodiment is poured into a mold to form a 40mmx40mmx40mm cube test block. After hardening and demolding, the test block is standard cured in a curing box for 28 days, then the obtained test piece is immersed in deionized water for 48 hours, then the total leaching amount a of heavy metal elements (Pb, Ni, Cr, Cu, Cd) is detected. At the same time, the original waste incineration fly ash without any modification treatment is used instead of the modified fly ash micro powder in step (3) of this embodiment to prepare a concrete material, and the test piece prepared from the concrete material (preparation method same as above) is used as a control sample to test the total leaching amount b of heavy metal elements, and then the heavy metal element solidification rate is calculated = (b-a) / b. (2) According to the "Standard Test Method for Physical and Mechanical Properties of Concrete" (GBT 50081-2019), the 28d compressive strength of the concrete material prepared in this embodiment is tested (as shown in Table 1). The test results of the above properties are as follows: solidification rate = 97.16%, compressive strength = 45.08MPa. Figure 2

[0030] Example 2 A preparation process of a waste incineration fly ash-based low-carbon concrete material, comprising the following steps: (1) The potassium silicate powder and the phosphogypsum powder are mixed with water according to a molar ratio of 1.3:1 of potassium silicate powder to phosphoric acid in the phosphogypsum powder, and then stirred uniformly to form a slurry with a solid content of 42wt.%. Then heated to 70℃ for 0.5 hours, then the obtained solid is ground, then the obtained powder is passed through a 100 mesh sieve to obtain modified gypsum powder.

[0031] ​(2) The components are mixed in a ratio of 6 parts by weight of the modified gypsum powder, 40 parts by weight of waste incineration fly ash, 1.5 parts by weight of 150-mesh re-burned magnesium oxide powder, 0.8 parts by weight of diethanolamine, 3.5 parts by weight of paraffin powder (the temperature at which it completely melts into a liquid is 78°C), and 120 parts by weight of water, and then stirred uniformly. Then, carbon dioxide is continuously introduced into the obtained slurry for 30 min (the introduction rate is 230 mL / min), and the slurry is continuously stirred during the process. After completion, the slurry is heated to 80°C to remove water, and then the obtained solid product is ground. The obtained powder is sieved through a 200-mesh sieve to obtain modified fly ash micropowder (as shown in Figure 1 ).

[0032] (3) The raw materials are weighed in the following proportions: cement (PO 42.5) 32 parts by weight, coarse aggregate 85 parts by weight, fine aggregate 41 parts by weight, modified fly ash micropowder 4 parts by weight, and polycarboxylic acid water reducer 0.65 parts by weight. The coarse aggregate is crushed stone with a particle size distribution of 5-12 mm, and the fine aggregate is river sand with a particle size distribution of 0.5-2 mm. The above raw materials are added to a mixer and dry-mixed for 3 min. Then, water is added according to a water-cement ratio of 0.44, and stirred for 3 min to obtain a concrete material.

[0033] Performance test: (1) The total leaching amount a of heavy metal elements of the test block prepared from the concrete material of the present example is tested by the same method as in Example 1 above. At the same time, the original waste incineration fly ash without any modification is used instead of the modified fly ash micropowder in step (3) of the present example to prepare a concrete material, and a test piece prepared from the concrete material (preparation method same as above) is used as a control sample to test the total leaching amount b of heavy metal elements, and then the heavy metal element immobilization rate = (b-a) / b is calculated. (2) The 28d compressive strength of the concrete material prepared in the present example is tested according to the "Standard Test Methods for Physical and Mechanical Properties of Concrete" (GBT 50081-2019) (as shown in Figure 2 ). The test results of the above performances are as follows: immobilization rate = 98.74%, compressive strength = 48.23 MPa.

[0034] Example 3 A preparation process of a waste incineration fly ash-based low-carbon concrete material, comprising the following steps: (1) The potassium silicate powder and phosphogypsum powder are mixed with water in a molar ratio of 1.2:1 of potassium silicate powder to phosphoric acid in the phosphogypsum powder, and then stirred uniformly to form a slurry with a solid content of 45 wt.%. Then, it is heated to 65°C and kept for 1 hour, then the obtained solid is ground, and then the obtained powder is sieved through a 300-mesh sieve to obtain modified gypsum powder.

[0035] (2) The components are mixed in a proportion of 11 parts by weight of the modified gypsum powder 11, 55 parts by weight of waste incineration fly ash, 2.5 parts by weight of 200-mesh re-burned magnesium oxide powder, 1.4 parts by weight of diethanolamine, 5 parts by weight of paraffin wax (the temperature at which it completely melts into a liquid is 92℃), and 130 parts by weight of water, and then stirred uniformly. Then, carbon dioxide is continuously introduced into the obtained slurry for 60 min (the introduction rate is 180 mL / min), and the slurry is continuously stirred during the process. After completion, the slurry is heated to 95℃ to remove moisture, and then the obtained solid product is ground. Then, the obtained powder is sieved through a 350-mesh sieve to obtain modified fly ash micropowder (as shown in Figure 1 ).

[0036] (3) The raw materials are weighed in the following proportions: cement (PO 42.5) 20 parts by weight, coarse aggregate 50 parts by weight, fine aggregate 27 parts by weight, modified fly ash micropowder 2 parts by weight, and polycarboxylic acid water reducer 0.3 parts by weight. The coarse aggregate is crushed stone with a particle size distribution of 5-12 mm, and the fine aggregate is river sand with a particle size distribution of 0.5-2 mm. The above raw materials are added to a mixer and dry-mixed for 3 min. Then, water is added according to a water-cement ratio of 0.38, and stirred for 3 min, to obtain a concrete material.

[0037] Performance test: (1) The total leaching amount a of heavy metal elements of the test block prepared from the concrete material of the present example is tested by the same method as in Example 1 above. At the same time, the original waste incineration fly ash without any modification is used instead of the modified fly ash micropowder in step (3) of the present example to prepare a concrete material, and a test piece prepared from the concrete material (preparation method same as above) is used as a control sample to test the total leaching amount b of heavy metal elements, and then the heavy metal element immobilization rate is calculated as (b-a) / b. (2) The 28d compressive strength of the concrete material prepared in the present example is tested according to the "Standard Test Methods for Physical and Mechanical Properties of Concrete" (GBT 50081-2019) (as shown in Figure 2 ). The test results of the above performances are as follows: immobilization rate = 94.51%, compressive strength = 47.66 MPa.

[0038] Example 4 A preparation process of a waste incineration fly ash-based low-carbon concrete material, comprising the following steps: (1) Phosphogypsum powder is mixed with water and stirred uniformly to form a slurry with a solid content of 45wt.%. Then, it is heated to 60℃ and kept for 1 hour. Then, the obtained solid is ground, and then the obtained powder is sieved through a 200-mesh sieve to obtain modified gypsum powder.

[0039] (2) Each component is mixed in a proportion of 8 parts by weight of the modified gypsum powder, 50 parts by weight of the waste incineration fly ash, 2 parts by weight of the heavy-burned magnesia powder of 300 mesh, 1.1 parts by weight of diethanolamine, 4 parts by weight of paraffin wax powder (the temperature at which it completely melts into a liquid is 78°C), and 127 parts by weight of water, and then stirred uniformly. Then, carbon dioxide is continuously introduced into the obtained slurry for 45 min (the introduction rate is 210 mL / min), and the slurry is continuously stirred during the process. After completion, the slurry is heated to 80°C to remove moisture, and then the obtained solid product is ground. Then, the obtained powder is sieved through a 300-mesh sieve to obtain the modified fly ash micropowder (as shown in Figure 1

[0040] (3) Each raw material is weighed in the following proportions: cement (PO 42.5) 26 parts by weight, coarse aggregate 70 parts by weight, fine aggregate 35 parts by weight, modified fly ash micropowder 3.5 parts by weight, and polycarboxylate superplasticizer 0.5 parts by weight. Among them, the coarse aggregate is gravel with a particle size distribution of 5-12 mm, and the fine aggregate is river sand with a particle size distribution of 0.5-2 mm. The above raw materials are added to a mixer and dry-mixed for 3 min. Then, water is added according to a water-cement ratio of 0.4, and stirred for 3 min to obtain a concrete material.

[0041] Performance test: (1) The total leaching amount a of heavy metal elements of the test block prepared from the concrete material of the present example is tested by the same method as in Example 1 above. At the same time, the original waste incineration fly ash without any modification is used instead of the modified fly ash micropowder in step (3) of the present example to prepare a concrete material, and a test piece prepared from the concrete material (preparation method same as above) is used as a control sample to test the total leaching amount b of heavy metal elements, and then the heavy metal element immobilization rate is calculated as (b-a) / b. (2) The 28d compressive strength of the concrete material prepared in the present example is tested according to the "Standard Test Methods for Physical and Mechanical Properties of Concrete" (GBT 50081-2019) (as shown in Figure 2

[0042] Example 5 A preparation process of a waste incineration fly ash-based low-carbon concrete material, comprising the following steps: (1) Potassium silicate powder and phosphogypsum powder are mixed with water in a molar ratio of 1.3:1 of potassium silicate powder to phosphoric acid in the phosphogypsum powder, and then stirred uniformly to form a slurry with a solid content of 42wt.%. Then, it is heated to 70°C and kept for 0.5 hours, then the obtained solid is ground, and then the obtained powder is sieved through a 100-mesh sieve to obtain modified gypsum powder.

[0043] ​​(2) Each component is mixed in a proportion of 6 parts by weight of the modified gypsum powder 6, 40 parts by weight of waste incineration fly ash, 1.5 parts by weight of 150 mesh re-burned magnesium oxide powder, 0.8 parts by weight of diethanolamine, and 120 parts by weight of water, and then stirred uniformly. Then, carbon dioxide is continuously introduced into the obtained slurry for 30 minutes (the introduction rate is 230 mL / min), and the slurry is continuously stirred during the process. After completion, the slurry is heated to 80°C to remove moisture, and then the obtained solid product is ground. Then, the obtained powder is sieved through a 200 mesh sieve to obtain a modified fly ash micro powder (as shown in Figure 1

[0044] (3) Each raw material is weighed in the following proportions: cement (PO 42.5) 32 parts by weight, coarse aggregate 85 parts by weight, fine aggregate 41 parts by weight, modified fly ash micro powder 4 parts by weight, and polycarboxylic acid water reducer 0.65 parts by weight. Among them, the coarse aggregate is gravel with a particle size distribution of 5-12 mm, and the fine aggregate is river sand with a particle size distribution of 0.5-2 mm. The above raw materials are added to a mixer and dry mixed for 3 minutes, then water is added according to a water-cement ratio of 0.44, and stirred for 3 minutes to obtain a concrete material.

[0045] Performance test: (1) The total leaching amount a of heavy metal elements of the test block prepared from the concrete material of the present embodiment is tested by the same method as in Example 1 above. At the same time, the original waste incineration fly ash without any modification is used instead of the modified fly ash micro powder in step (3) of the present embodiment to prepare a concrete material, and a test piece prepared from the concrete material (preparation method same as above) is used as a control sample to test the total leaching amount b of heavy metal elements, and then the heavy metal element immobilization rate is calculated as (b-a) / b. (2) The 28d compressive strength of the concrete material prepared in the present embodiment is tested according to the "Standard Test Methods for Physical and Mechanical Properties of Concrete" (GBT 50081-2019). The test results of the above properties are as follows: immobilization rate = 82.37%, compressive strength = 48.86 MPa.

[0046] Example 6 A preparation process of a waste incineration fly ash-based low-carbon concrete material, comprising the following steps: (1) Potassium silicate powder and phosphogypsum powder are mixed with water in a molar ratio of 1.5:1 of potassium silicate powder to phosphoric acid in the phosphogypsum powder, and then stirred uniformly to form a slurry with a solid content of 45wt.%. Then heated to 60°C for 1 hour, then the obtained solid material is ground, and then the obtained powder is sieved through a 200 mesh sieve to obtain a modified gypsum powder.

[0047] ​(2) The components are mixed in a ratio of 8 parts by weight of the modified gypsum powder, 50 parts by weight of the waste incineration fly ash, 2 parts by weight of the heavy-burned magnesium oxide powder of 300 mesh, 1.1 parts by weight of diethanolamine, 4 parts by weight of paraffin powder (the temperature at which it completely melts into a liquid is 78°C), and 127 parts by weight of water, and then stirred uniformly. The obtained slurry is then heated to 80°C to remove moisture, and then the obtained solid product is ground. The obtained powder is then sieved through a 300-mesh sieve to obtain the modified fly ash micro-powder (as shown in Figure 1

[0048] (3) The raw materials are weighed in the following proportions: cement (PO 42.5) 26 parts by weight, coarse aggregate 70 parts by weight, fine aggregate 35 parts by weight, modified fly ash micro-powder 3.5 parts by weight, and polycarboxylic acid water reducer 0.5 parts by weight. The coarse aggregate is crushed stone with a particle size distribution of 5-12 mm, and the fine aggregate is river sand with a particle size distribution of 0.5-2 mm. The above raw materials are added to a mixer and dry-mixed for 3 min. Then, water is added according to a water-cement ratio of 0.4, and stirred for 3 min to obtain a concrete material.

[0049] Performance test: (1) The total leaching amount a of heavy metal elements of the test block prepared from the concrete material of the present embodiment is tested by the same method as in Example 1 above. At the same time, the original waste incineration fly ash without any modification is used instead of the modified fly ash micro-powder in step (3) of the present embodiment to prepare a concrete material, and a test piece prepared from the concrete material (preparation method same as above) is used as a control sample to test the total leaching amount b of heavy metal elements, and then the heavy metal element immobilization rate is calculated as (b-a) / b. (2) The 28d compressive strength of the concrete material prepared in the present embodiment is tested according to the "Standard Test Methods for Physical and Mechanical Properties of Concrete" (GBT 50081-2019). The test results of the above properties are as follows: immobilization rate = 63.92%, compressive strength = 44.71 MPa.

[0050] Example 7 A preparation process of a waste incineration fly ash-based low-carbon concrete material, comprising the following steps: (1) The potassium silicate powder and phosphogypsum powder are mixed with water in a molar ratio of 1.2:1 of potassium silicate powder to phosphoric acid in the phosphogypsum powder, and then stirred uniformly to form a slurry with a solid content of 45wt.%. Then heated to 65°C for 1 hour, then the obtained solid material is ground, and then the obtained powder is sieved through a 300-mesh sieve to obtain a modified gypsum powder.

[0051] ​(2) The components are mixed in the proportions of 11 parts by weight of the modified gypsum powder 11, 55 parts by weight of waste incineration fly ash, 2.5 parts by weight of 200-mesh re-burned magnesium oxide powder, 5 parts by weight of paraffin powder (the temperature at which it completely melts into a liquid is 92°C), and 130 parts by weight of water, and then stirred uniformly. Then, carbon dioxide is continuously introduced into the obtained slurry for 60 min (the introduction rate is 180 mL / min), and the slurry is continuously stirred during the process. After completion, the slurry is heated to 95°C to remove moisture, and then the obtained solid product is ground. Then, the obtained powder is sieved through a 350-mesh sieve to obtain the modified fly ash micro powder.

[0052] (3) The raw materials are weighed in the following proportions: 20 parts by weight of cement (PO 42.5), 50 parts by weight of coarse aggregate, 27 parts by weight of fine aggregate, 2 parts by weight of the modified fly ash micro powder, and 0.3 parts by weight of polycarboxylic acid water reducer. The coarse aggregate is crushed stone with a particle size distribution of 5-12 mm, and the fine aggregate is river sand with a particle size distribution of 0.5-2 mm. The above raw materials are added to a mixer and dry-mixed for 3 min. Then, water is added according to a water-cement ratio of 0.38, and stirred for 3 min, to obtain a concrete material.

[0053] Performance test: (1) The total leaching amount a of heavy metal elements of the test block prepared from the concrete material of the present embodiment is tested by the same method as in Example 1 above. At the same time, the original waste incineration fly ash without any modification is used instead of the modified fly ash micro powder in step (3) of the present embodiment to prepare a concrete material, and a test piece prepared from the concrete material (preparation method same as above) is used as a control sample to test the total leaching amount b of heavy metal elements. Then, the heavy metal element immobilization rate is calculated as (b-a) / b. (2) The 28d compressive strength of the concrete material prepared in the present embodiment is tested according to the “Standard Test Method for Physical and Mechanical Properties of Concrete” (GBT 50081-2019). The test results of the above performances are as follows: immobilization rate = 87.28%, compressive strength = 47.14 MPa.

[0054] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A process for preparing low-carbon concrete material based on fly ash from garbage incineration, characterized in that: The steps include: (1) Phosphogypsum powder, potassium silicate powder and water are mixed and stirred evenly to convert the phosphoric acid in the phosphogypsum powder into potassium dihydrogen phosphate; the resulting slurry is then dried and ground to obtain modified gypsum powder; (2) The modified gypsum powder, waste incineration fly ash, dead-burned magnesium oxide powder, diethanolamine, paraffin powder, and water are mixed to form a slurry, and then carbon dioxide is continuously introduced into the slurry for treatment. After completion, the slurry is dried above the melting temperature of the paraffin to remove moisture, and the obtained solid product is ground to obtain modified fly ash micropowder; (3) Cement, coarse aggregate, fine aggregate, the modified fly ash powder and water reducing agent are used as raw materials, mixed evenly and then added with water to obtain concrete material.

2. The process for preparing waste incineration fly ash-based low-carbon concrete material according to claim 1, characterized in that: In step (1), the molar ratio of the potassium silicate powder to the phosphoric acid in the phosphogypsum powder is 1.2-1.5:

1.

3. The process for preparing waste incineration fly ash-based low-carbon concrete material according to claim 1, characterized in that: In step (1), the drying temperature is 60-70° C. and the drying time is not less than 30 min. Optionally, in step (1), the powder obtained after the grinding is passed through a 100-300 mesh to obtain the modified gypsum powder.

4. The process for preparing waste incineration fly ash-based low-carbon concrete material according to claim 1, characterized in that: In step (2), the ratio of the modified gypsum powder, waste incineration fly ash, dead-burned magnesium oxide powder, diethanolamine, paraffin powder and water is 6-11 parts by weight: 40-55 parts by weight: 1.5-2.5 parts by weight: 0.8-1.4 parts by weight: 3.5-5 parts by weight: 120-130 parts by weight; optionally, the fineness of the dead-burned magnesium oxide powder is not less than 150 mesh.

5. The process for preparing waste incineration fly ash-based low-carbon concrete material according to claim 1, characterized in that: In step (2), the carbon dioxide is introduced at a rate of 180 to 230 mL / min, and the continuous introduction time is 30 to 60 min.

6. The process for preparing waste incineration fly ash-based low-carbon concrete material according to claim 1, characterized in that: In step (2), the drying temperature is 2-5°C higher than the temperature at which the paraffin completely melts into a liquid state.

7. The process for preparing waste incineration fly ash-based low-carbon concrete material according to claim 1, characterized in that: In step (2), the powder obtained after the grinding is passed through a 200-350 mesh sieve to obtain the modified fly ash fine powder.

8. The process for preparing waste incineration fly ash-based low-carbon concrete material according to claim 1, characterized in that: In step (3), the ratio of the cement, coarse aggregate, fine aggregate, the modified fly ash powder and the water reducer is 20-32 parts by weight: 50-85 parts by weight: 27-41 parts by weight: 2-4 parts by weight: 0.3-0.65 parts by weight.

9. The process for preparing the waste incineration fly ash-based low-carbon concrete material according to any one of claims 1 to 8, characterized in that: In step (3), water is added according to a water-cement ratio of 0.38 to 0.

44.

10. The process for preparing the waste incineration fly ash-based low-carbon concrete material according to any one of claims 1 to 8, characterized in that: In step (3), the water reducer includes at least one of a polycarboxylic acid water reducer, a naphthalene-based water reducer, a lignin sulfonate-based water reducer, and a melamine-based water reducer.

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