A biochar-modified waste incineration fly ash-based carbon sequestration artificial aggregate and its preparation method

Abstract

The present invention discloses a biochar-modified garbage incineration fly ash-based carbon-fixing artificial aggregate and a preparation method thereof, which utilizes the chemical composition complementarity mechanism between garbage incineration fly ash, granulated blast furnace slag and desulfurized gypsum, and is mixed with porous and lightweight biochar, and a new, low-carbon, all-solid waste-based, lightweight and high-strength artificial aggregate is prepared through scientific formula design and reasonable process route optimization. The present invention greatly reduces the occupation of land resources and the potential risk of secondary environmental pollution caused by landfill, and at the same time realizes the resource utilization of three types of solid wastes, namely garbage incineration fly ash, granulated blast furnace slag and desulfurized gypsum, and converts them into lightweight and high-strength carbon-fixing artificial aggregates under the modification of biochar, further reducing the demand for mining of natural sand and gravel aggregates.

Description

Technical Field

[0001] The present invention relates to the technical field of safe disposal and resource utilization of solid waste, and particularly relates to a biochar-modified carbon-fixing artificial aggregate based on waste incineration fly ash and a preparation method thereof. Background Art

[0002] In recent years, in order to alleviate the problem of depletion of natural sand and gravel aggregates caused by excessive consumption of natural resources, the recovery of solid waste to prepare high-performance artificial aggregates has attracted extensive attention from researchers, which also provides a feasible way for the large-scale disposal and resource utilization of waste incineration fly ash. The preparation technologies of artificial aggregates mainly include high-temperature sintering technology and cold bonding technology. Among them, high-temperature sintering technology is accompanied by huge energy consumption and carbon dioxide emissions, and at the same time, it is easy to cause the volatilization of heavy metals and other pollutants in waste incineration fly ash, thus generating secondary pollution problems. Therefore, this technology is not suitable for the resource utilization of waste incineration fly ash. The cold bonding technology is based on different cementitious systems, and uses the hydration reaction or geopolymerization reaction of cementitious materials to achieve the hardening of aggregates, and fixes the endogenous pollutants of raw materials through various physicochemical mechanisms such as physical encapsulation, chemical adsorption and covalent bonding of reaction products, which has the advantages of low energy consumption and high environmental benefits. At the same time, waste incineration fly ash contains 30-40% calcium oxide, which can undergo geopolymerization reaction with other solid wastes rich in silicon-aluminum phases to generate gel products. Therefore, through scientific component formulation, high-performance waste incineration fly ash-based artificial aggregates can be prepared by using the cold bonding technology, so as to realize the green and safe disposal and resource utilization of waste incineration fly ash.

[0003] Biochar is a light and porous negative carbon material, with characteristics such as high porosity, high specific surface area, and high water absorption rate. Existing research shows that adding an appropriate amount of biochar to cement-based materials can significantly improve the volume stability of cement-based materials and enhance their mechanical properties due to its internal curing effect. At the same time, the high porosity of biochar and its high affinity for non-polar compounds make it have excellent CO 2 adsorption capacity. Incorporating biochar into waste incineration fly ash-based artificial aggregates, through scientific design of raw material ratios, lightweight and high-strength new carbon-fixing artificial aggregates can be produced, but the related exploration and research are still lacking at present. Therefore, there is an urgent need to find a preparation method for biochar-modified carbon-fixing artificial aggregates based on waste incineration fly ash to realize the resource utilization and value-added utilization of solid waste.

[0004] The present invention mainly aims at the following existing technical problems:

[0005] (1) The components of waste incineration fly ash are complex and the output is huge, and its large-scale resource utilization rate is low;

[0006] (2) The production and application of traditional artificial aggregates are often accompanied by a large amount of carbon emissions, and the product functions are single. Summary of the Invention

[0007] The object of the present invention is to propose a biochar-modified waste incineration fly ash-based carbon sequestration artificial aggregate and its preparation method. By utilizing the chemical composition complementary mechanism among waste incineration fly ash, granulated blast furnace slag, and desulfurized gypsum, and incorporating porous and lightweight biochar, a new type of low-carbon, all-solid waste-based lightweight and high-strength artificial aggregate is prepared through scientific formula design and reasonable process route optimization. At the same time, the artificial aggregate prepared by this method also has excellent mechanical properties and outstanding CO 2 absorption and sequestration capabilities.

[0008] To achieve the above object, the present invention proposes a method for preparing artificial aggregates by using waste incineration fly ash, granulated blast furnace slag, desulfurized gypsum, and biochar as raw materials through disk granulation technology. The present invention is realized through the following technical solutions:

[0009] The present invention discloses a biochar-modified waste incineration fly ash-based carbon sequestration artificial aggregate. The artificial aggregate is a spherical aggregate with calcium silicoaluminate hydrate gel, ettringite, and Friedel's salt as the main hydration products. Among them, the raw materials used to prepare the biochar-modified waste incineration fly ash-based carbon sequestration artificial aggregate include waste incineration fly ash, granulated blast furnace slag, desulfurized gypsum, and a certain amount of biochar is added to enhance the CO 2 absorption and sequestration capabilities of the artificial aggregate.

[0010] The present invention also discloses a preparation method for a biochar-modified waste incineration fly ash-based carbon sequestration artificial aggregate, which includes the following steps:

[0011] S1: Uniformly mix waste incineration fly ash, granulated blast furnace slag, desulfurized gypsum, and biochar in a mass ratio of 20 - 25:55 - 65:10 - 15:4 - 12 to obtain a mixed dry material, where the waste incineration fly ash needs to be dried to a constant weight under high-temperature conditions before mixing;

[0012] S2: Weigh a part of the mixed dry material, mix deionized water with the part of the mixed dry material and stir to obtain a mixed wet material. When the mixed wet material turns into a large number of independent aggregates with a diameter of 0.5 - 1 mm, quickly transfer it to a disk granulator with an inclination angle of 45 - 55° and a rotation speed of 40 - 75 r / min;

[0013] S3: Add a part of the mixed dry material and deionized water in a corresponding proportion every 2 - 5 minutes, and add the mixed dry material and the corresponding proportion of deionized water 3 - 5 times in total. When continuous particle size distribution of fresh spheres is generated in the disk granulator, the granulation ends, and the fresh spheres are called the first aggregate pre-products;

[0014] S4: Screen the first prefabricated aggregate using 2.36 mm, 4.75 mm, 9.5 mm, 16 mm, and 20 mm standard sieves to obtain the second prefabricated aggregate;

[0015] S5: Transfer the obtained second prefabricated aggregate into a standard curing box for standard curing for at least 28 days to obtain the finished aggregate.

[0016] As a further improvement, the waste incineration fly ash in step S1 of the present invention is detoxified fly ash after low-temperature pyrolysis and multi-stage water washing.

[0017] As a further improvement, the biochar in step S1 of the present invention needs to be ground before mixing to make its particles smaller than 2.36 mm.

[0018] As a further improvement, the mass ratio of deionized water to the taken part of the mixed dry material in step S2 of the present invention is 0.34 - 0.31:1.0.

[0019] As a further improvement, the mass ratio of deionized water to the taken part of the mixed dry material in step S3 of the present invention is 0.24 - 0.22:1.0

[0020] As a further improvement, after screening the first prefabricated aggregate according to the required particle size range in step S4 of the present invention, it includes coarse aggregate with a particle size of 4.75 - 20 mm and fine aggregate with a particle size of 2.36 - 4.75 mm.

[0021] As a further improvement, the standard curing conditions in step S5 of the present invention are a temperature of 20 ± 2 °C and a relative humidity of ≥ 95%.

[0022] The present invention provides a new approach for the safe disposal and resource utilization of waste incineration fly ash. Based on the chemical composition complementary mechanism between different solid wastes, the component formulation is scientifically optimized to synergistically recycle waste incineration fly ash, granulated blast furnace slag, and desulfurized gypsum. At the same time, it is modified by incorporating biochar to prepare waste incineration fly ash-based carbon-fixing artificial aggregates.

[0023] Compared with the prior art, the features and beneficial effects of the present invention are:

[0024] (1) The raw material ratio proposed by the present invention, i.e., waste incineration fly ash: granulated blast furnace slag: desulfurized gypsum: biochar = (20 - 25):(55 - 65):(10 - 15):(4 - 12), makes full use of the characteristics of waste incineration fly ash rich in alkaline calcium salts, synergistically prepares cold-bonded artificial aggregates from multiple solid wastes, realizes the high-dose recovery and resource utilization of waste incineration fly ash, and has lower carbon emissions compared with the production process of traditional artificial aggregates;

[0025] (2) The present invention innovatively proposes to modify the refuse incineration fly ash-based artificial aggregate with biochar. On the one hand, by utilizing the internal curing effect of biochar, lightweighting is achieved while ensuring the cylinder compressive strength of the artificial aggregate. On the other hand, based on the characteristics of high porosity and high specific surface area of biochar, the absorption and sequestration capacity of the artificial aggregate for CO 2 is enhanced, endowing the artificial aggregate with the function of carbon sequestration, and at the same time further reducing the carbon emissions during the production and application of the artificial aggregate. (3) The present invention uses the disk granulation technology to prepare cold-bonded artificial aggregate. By selecting appropriate disk inclination angles (45-55°) and rotation speeds (40-75 r / min), an efficient preparation process path for the refuse incineration fly ash-based artificial aggregate is formed. At the same time, compared with the traditional high-temperature sintering method for preparing artificial aggregate, the energy consumption is lower and there is no problem of secondary pollution caused by pollutant volatilization. The overall preparation process is more green and low-carbon.

[0026] Generally speaking, compared with the traditional landfill disposal method of refuse incineration fly ash, the present invention greatly reduces the occupation of land resources caused by landfill and the potential risk of environmental secondary pollution. At the same time, the resource utilization of three types of solid waste, namely refuse incineration fly ash, granulated blast furnace slag, and desulfurized gypsum, is realized. Under the modification of biochar, they are transformed into lightweight and high-strength carbon sequestration artificial aggregates, further reducing the demand for the exploitation of natural sand and gravel aggregates. Description of the Drawings

[0027] Figure 1 is a schematic flow chart of the method for preparing biochar-modified refuse incineration fly ash-based carbon sequestration artificial aggregate proposed in the embodiment of the present invention. Detailed Embodiments

[0028] The present invention provides a biochar-modified refuse incineration fly ash-based carbon sequestration artificial aggregate and a preparation method. To make the purpose, technical solution and effect of the present invention clearer and more definite, the following further details the present invention. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] The embodiment of the present invention provides a method for preparing an artificial aggregate using refuse incineration fly ash, granulated blast furnace slag, desulfurized gypsum, and biochar as the main raw materials, as Figure 1 shown.

[0030] In some specific embodiments, in order to avoid moisture agglomeration of the raw materials, resulting in uneven mixing, it is necessary to pre-dry the refuse incineration fly ash before mixing the raw materials to keep it in a uniform powder state.

[0031] The following is a further explanatory description of the biochar-modified waste incineration fly ash-based carbon sequestration artificial aggregate and its preparation method proposed by the present invention through specific embodiments: Example 1

[0032] A biochar-modified waste incineration fly ash-based carbon sequestration artificial aggregate and its preparation method are as follows:

[0033] (1) Place the waste incineration fly ash in a blast drying oven at 60 °C and dry it for at least 24 h until constant weight, then take it out for subsequent use;

[0034] (2) Put the biochar into a mortar for grinding, and screen the ground powder through an 8-mesh (2.36 mm) standard sieve. The screened biochar powder is used as raw material for subsequent use;

[0035] (3) Compatibility of waste incineration fly ash, granulated blast furnace slag, desulfurized gypsum, and biochar in a mass ratio of 20:65:15:4, and uniformly mix them for 2 min at a speed of 200 r / min using a stirrer to obtain a mixed dry powder;

[0036] (4) Weigh a part of the mixed dry material, mix and stir deionized water and this part of the mixed dry material in a mass ratio of 0.34:1.0. When the mixed wet material turns into a large number of independent aggregates with a diameter of 0.5 - 1 mm, quickly transfer it to a disk granulator with an inclination angle of 45° and a rotation speed of 75 r / min;

[0037] (5) Add a part of the mixed dry material and deionized water with a mass ratio of 0.24:1.0 to this part of the mixed dry material every 4 minutes, and add the mixed dry material and the corresponding proportion of deionized water a total of 4 times. When continuous particle size distribution of fresh spheres is generated in the disk granulator, the granulation ends. This fresh sphere is called the first aggregate preform;

[0038] (6) Screen the first aggregate preform using 2.36 mm, 4.75 mm, 9.5 mm, 16 mm, and 20 mm standard sieves to obtain the second aggregate preform;

[0039] (7) Transfer the obtained second aggregate preform to a standard curing box for standard curing (temperature 20 ± 2 °C, relative humidity ≥ 95%) for at least 28 days to obtain the finished aggregate.

[0040] Perform performance tests on the obtained finished aggregate according to GB / T 17431.1 - 2010 "Lightweight Aggregates and Their Test Methods", and the test results are shown in Table 1:

[0041] Table 1 shows the physical properties of the aggregate in Example 1

[0042] <![CDATA[Bulk density (kg / m 3 )]]> <![CDATA[Apparent density (kg / m 3 )]]> Cylinder compressive strength (MPa) 1 h water absorption rate (%) <![CDATA[CO 2 Absorbing capacity (g / 100g)]]> Example 1 1020.2 1672.4 10.6 12.7 4.3 Example 2

[0043] A biochar-modified waste incineration fly ash-based carbon sequestration artificial aggregate and its preparation method are as follows:

[0044] (1) Place the waste incineration fly ash in a blast drying oven at 60 °C and dry it for at least 24 h until constant weight, then take it out for subsequent use;

[0045] (2) Put the biochar into a mortar and grind it. The ground powder is screened through an 8-mesh (2.36 mm) standard sieve, and the screened biochar powder is used as a raw material for subsequent use;

[0046] (3) Compatibility of waste incineration fly ash, granulated blast furnace slag, desulfurized gypsum, and biochar in a mass ratio of 20:65:15:8, and use a stirrer to mix evenly at a speed of 200 r / min for 2 min to obtain a mixed dry powder;

[0047] (4) Weigh a part of the mixed dry material, mix deionized water and this part of the mixed dry material in a mass ratio of 0.32:1.0 and stir. When the mixed wet material turns into a large number of independent aggregates with a diameter of 0.5 - 1 mm, quickly transfer it to a disk granulator with an inclination angle of 45° and a rotation speed of 75 r / min;

[0048] (5) Add a part of the mixed dry material and deionized water with a mass ratio of 0.22:1.0 to this part of the mixed dry material every 4 minutes, and add the mixed dry material and the corresponding proportion of deionized water 4 times in total. When continuous particle size distribution of fresh spheres is generated in the disk granulator, the granulation ends. This fresh sphere is called the first aggregate preform;

[0049] (6) Screen the first aggregate preform using 2.36 mm, 4.75 mm, 9.5 mm, 16 mm, and 20 mm standard sieves to obtain the second aggregate preform;

[0050] (7) Transfer the obtained second aggregate preform to a standard curing box for standard curing (temperature 20 ± 2 °C, relative humidity ≥ 95%) for at least 28 days to obtain the finished aggregate.

[0051] Perform performance tests on the obtained finished aggregate according to GB / T 17431.1-2010 "Lightweight Aggregates and Their Test Methods", and the test results are shown in Table 2:

[0052] Table 2 is the physical properties of the aggregate in Example 2

[0053] <![CDATA[Bulk density (kg / m 3 ).]]> <![CDATA[Apparent density (kg / m 3 )]]> Cylinder compressive strength (MPa) 1 h water absorption rate (%) <![CDATA[CO 2 Absorbing capacity (g / 100g)]]> Example 2 957.7 1473.4 8.2 14.4 5.5 Example 3

[0054] A biochar-modified waste incineration fly ash-based carbon sequestration artificial aggregate and its preparation method are as follows:

[0055] (1)Place the waste incineration fly ash in a forced-air drying oven at 60 °C and dry it for at least 24 h until constant weight, then take it out for subsequent use;

[0056] (2)Put the biochar into a mortar and grind it. The ground powder is screened through a 8-mesh (2.36 mm) standard sieve, and the screened biochar powder is used as raw material for subsequent use;

[0057] (3)Comply with the mass ratio of 20:65:15:12 for the waste incineration fly ash, granulated blast furnace slag, desulfurized gypsum, and biochar, and use a stirrer to uniformly mix them at a speed of 200 r / min for 2 min to obtain a mixed dry powder;

[0058] (4)Weigh a part of the mixed dry material, mix and stir deionized water and this part of the mixed dry material at a mass ratio of 0.31:1.0. When the mixed wet material turns into a large number of independent aggregates with a diameter of 0.5 - 1 mm, quickly transfer it to a disk granulator with an inclination angle of 45° and a rotation speed of 75 r / min;

[0059] (5)Add a part of the mixed dry material and deionized water with a mass ratio of 0.22:1.0 to this part of the mixed dry material every 4 minutes, and add the mixed dry material and the corresponding proportion of deionized water 4 times in total. When continuous particle size distribution of fresh spheres is generated in the disk granulator, the granulation ends. This fresh sphere is called the first aggregate preform;

[0060] (6)Screen the first aggregate preform using 2.36 mm, 4.75 mm, 9.5 mm, 16 mm, and 20 mm standard sieves to obtain the second aggregate preform;

[0061] (7)Transfer the obtained second aggregate preform to a standard curing box for standard curing (temperature 20 ± 2 °C, relative humidity ≥ 95 %) for at least 28 days to obtain the finished aggregate.

[0062] Perform performance tests on the obtained finished aggregate according to GB / T 17431.1-2010 "Lightweight Aggregates and Their Test Methods", and the test results are shown in Table 3:

[0063] Table 3 is the physical properties of the aggregate in Example 3

[0064] <![CDATA[Bulk density (kg / m 3 )]]> <![CDATA[Apparent density (kg / m 3 ).]]> Cylinder compressive strength (MPa) 1 h water absorption rate (%) <![CDATA[CO 2 Absorbing capacity (g / 100g)]]> Example 3 848.4 1325.7 7.3 16.3 7.1 Comparative Example 1

[0065] In this comparative example, the selection of waste incineration fly ash, granulated blast furnace slag, and desulfurized gypsum and the raw material ratio are the same as those in Example 1.

[0066] The operation process of this comparative example is different from that of Example 1 in that no biochar is incorporated in this comparative example, and the following adjustments are made to each step:

[0067] (1) Place the municipal solid waste incineration fly ash in a blast drying oven at 60 °C and dry it for at least 24 h until constant weight, then take it out for subsequent use;

[0068] (2) Compatibility of municipal solid waste incineration fly ash, granulated blast furnace slag, and desulfurized gypsum in a mass ratio of 20:65:15, and uniformly mix them for 2 min under the action of a stirrer rotating at 200 r / min to obtain a mixed dry powder;

[0069] (3) Weigh a part of the mixed dry material, mix deionized water and this part of the mixed dry material in a mass ratio of 0.35:1.0 and stir. When the mixed wet material turns into a large number of independent aggregates with a diameter of 0.5 - 1 mm, quickly transfer it to a disk granulator with an inclination angle of 45° and a rotation speed of 75 r / min;

[0070] (4) Add a part of the mixed dry material and deionized water with a mass ratio of 0.25:1.0 to this part of the mixed dry material every 4 minutes, and add the mixed dry material and the corresponding proportion of deionized water 4 times in total. When fresh spheres with a continuous particle size distribution are produced in the disk granulator, the granulation ends. This fresh sphere is called the first pre - finished aggregate;

[0071] (5) Screen the first pre - finished aggregate using 2.36 mm, 4.75 mm, 9.5 mm, 16 mm, and 20 mm standard sieves to obtain the second pre - finished aggregate;

[0072] (6) Transfer the obtained second pre - finished aggregate to a standard curing box for standard curing (temperature 20 ± 2 °C, relative humidity ≥ 95%) for at least 28 days to obtain the finished aggregate.

[0073] Perform performance tests on the obtained finished aggregate according to GB / T 17431.1 - 2010 "Lightweight Aggregates and Their Test Methods". The test results are shown in Table 4:

[0074] Table 4 is the physical properties of the aggregate in Comparative Example 1

[0075] <![CDATA[Bulk density (kg / m 3 ).]]> <![CDATA[Apparent density (kg / m 3 )]]> Cylinder compressive strength (MPa) 1 h water absorption rate (%) <![CDATA[CO 2 Absorbing capacity (g / 100g)]]> Comparative Example 1 1117.7 1774.2 8.7 11.2 3.2

[0076] Through the comparative analysis of Comparative Example 1 and Examples 1, 2, and 3, it can be found that with the increase in the biochar content, the bulk density of the artificial aggregate has been greatly improved, from 1117.7 kg / m³ in Comparative Example 1 3 decreased to 848.4 kg / m³ in Example 3 3. Generally speaking, the bulk density and cylinder compressive strength of aggregates are two conflicting indicators. However, due to the internal curing effect of biochar, after adding an appropriate amount of biochar, the cylinder compressive strength of artificial aggregates increased from 8.7 MPa in Comparative Example 1 to 10.6 MPa in Example 1. Then, as the biochar content increased, the cylinder compressive strength of artificial aggregates was adversely affected. At the same time, the high porosity of biochar and its high affinity for non-polar compounds endow artificial aggregates with stronger CO 2 absorption capacity. As the biochar content increased, the CO 2 absorption capacity of artificial aggregates increased from 3.2 g / 100g in Comparative Example 1 to 7.1 g / 100g in Example 3. Generally speaking, biochar has an excellent improvement effect on the bulk density and CO 2 absorption capacity of artificial aggregates. However, excessive addition of biochar will significantly weaken the mechanical properties of artificial aggregates. Therefore, when using biochar to modify artificial aggregates, it is necessary to control the biochar content to reduce its bulk density while ensuring the mechanical properties of artificial aggregates, so as to achieve the preparation of lightweight, high-strength, and carbon-fixing artificial aggregates.

[0077] The above are only the preferred embodiments of the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible changes and modifications to the technical solutions of the present invention by using the methods and technical contents disclosed above, or modify them into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solutions of the present invention still fall within the scope of protection of the technical solutions of the present invention.

Claims

1. A biochar-modified waste incineration fly ash-based carbon-fixing artificial aggregate, characterized in that: The artificial aggregate is a spherical aggregate with hydrated calcium aluminosilicate gel, ettringite and Freund's salt as the main hydration products, wherein the raw materials used to prepare the biochar-modified garbage incineration fly ash-based carbon-fixing artificial aggregate include garbage incineration fly ash, granulated blast furnace slag, desulfurized gypsum, and a certain amount of biochar is added to enhance the CO2 absorption and storage capacity of the artificial aggregate; the preparation method of the artificial aggregate comprises the following steps: S1: uniformly mix waste incineration fly ash, granulated blast furnace slag, desulfurized gypsum and biochar in a mass ratio of 20-25:55-65:10-15:4-12 to obtain a mixed dry material, wherein the waste incineration fly ash needs to be dried to a constant weight under high temperature conditions before mixing; S2: Weigh part of the mixed dry material, mix and stir the deionized water with the part of the mixed dry material to obtain a mixed wet material, and when the mixed wet material is transformed into a large number of independent agglomerates with a diameter of 0.5-1 mm, quickly transfer it to a disc granulator with an inclination angle of 45-55° and a rotation speed of 40-75 r / min; S3: adding part of the mixed dry materials and deionized water in a corresponding proportion to the part of the mixed dry materials every 2-5 minutes, adding the mixed dry materials and deionized water in a corresponding proportion to the part of the mixed dry materials 3-5 times in total, and the granulation is completed when fresh spheres with continuous particle size distribution are generated in the disc granulator, and the fresh spheres are called the first aggregate pre-finished product; S4: using 2.36 mm, 4.75 mm, 9.5 mm, 16 mm, and 20 mm standard sieves to sieve the first aggregate pre-finished product to obtain a second aggregate pre-finished product; S5: transferring the obtained second aggregate pre-finished product into a standard curing box for standard curing for at least 28 days to obtain a finished aggregate product; The waste incineration fly ash in step S1 is detoxified fly ash after low-temperature pyrolysis and multi-stage water washing; In the step S2, the mass ratio of deionized water to the mixed dry material is 0.34-0.31:1.0; In step S3, the mass ratio of deionized water to the mixed dry material is 0.24-0.22:1.0; In the step S4, the first aggregate pre-product is screened according to the required particle size range, including coarse aggregate with a particle size of 4.75-20 mm and fine aggregate with a particle size of 2.36-4.75 mm; The standard curing conditions in step S5 are a temperature of 20±2° C. and a relative humidity of ≥95%.

2. The biochar-modified waste incineration fly ash-based carbon-fixing artificial aggregate according to claim 1, characterized in that: The biochar in step S1 needs to be ground before mixing so that its particles are smaller than 2.36 mm.

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