Biochar-modified waste incineration fly ash-based carbon sequestration artificial aggregate and preparation method thereof

Abstract

The invention discloses a biochar-modified waste incineration fly ash-based carbon sequestration artificial aggregate and a preparation method thereof, a chemical component complementation mechanism among waste incineration fly ash, granulated blast furnace slag and desulfurized gypsum is utilized, porous and light biochar is doped, and the biochar-modified waste incineration fly ash-based carbon sequestration artificial aggregate is prepared through scientific formula design and reasonable process route optimization. The novel and low-carbon all-solid-waste-based light-weight high-strength artificial aggregate is prepared. According to the method, land resource occupation caused by landfill and potential secondary environmental pollution risks are greatly reduced, meanwhile, resource utilization of the three kinds of solid waste including the waste incineration fly ash, the granulated blast furnace slag and the desulfurized gypsum is achieved, and the solid waste is converted into the light and high-strength carbon sequestration artificial aggregate under the modification effect of the biochar; and the mining requirement on the natural gravel aggregate is further reduced.

Description

Technical Field

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

[0002] In recent years, in order to alleviate the problem of natural sand and gravel aggregate depletion caused by excessive consumption of natural resources, the recycling of solid waste to prepare high-performance artificial aggregates has attracted widespread attention from researchers, which also provides a feasible way out for the large-scale disposal and resource utilization of waste incineration fly ash. The preparation technology of artificial aggregates mainly includes high-temperature sintering technology and cold bonding technology. Among them, high-temperature sintering technology is accompanied by huge energy consumption and carbon dioxide emissions. At the same time, it is easy to cause the volatilization of pollutants such as heavy metals in waste incineration fly ash, thereby causing 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, using the hydration reaction or geological polymerization reaction of cementitious materials to achieve aggregate hardening, and through various physical and chemical mechanisms such as physical encapsulation, chemical adsorption and covalent bonding of reaction products to achieve the fixation of endogenous pollutants in raw materials, 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 and aluminum phases to generate gel products. Therefore, through scientific composition and cold bonding technology, high-performance waste incineration fly ash-based artificial aggregates can be prepared, thereby realizing the green and safe disposal and resource utilization of waste incineration fly ash.

[0003] Biochar is a lightweight, porous, negative carbon material with the characteristics of high porosity, high specific surface area, and high water absorption. Studies have shown 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 give it excellent CO2 adsorption capacity. By adding biochar to waste incineration fly ash-based artificial aggregates and scientifically designing the raw material ratio, it is possible to produce lightweight, high-strength new carbon-fixing artificial aggregates, but related exploration and research are still lacking. Therefore, it is urgent to find a method for preparing biochar-modified waste incineration fly ash-based carbon-fixing artificial aggregates to realize the resource and value-added utilization of solid waste.

[0004] The present invention mainly aims at the following existing technical problems: (1) The composition of fly ash from waste incineration is complex and the output is huge, so its large-scale resource utilization rate is low; (2) The production and application of traditional artificial aggregates are often accompanied by large amounts of carbon emissions, and the products have only a single function. Summary of the invention

[0005] The purpose of the present invention is to propose a biochar-modified waste incineration fly ash-based carbon-fixing artificial aggregate and a preparation method thereof, which utilizes the chemical composition complementarity mechanism between waste incineration fly ash, granulated blast furnace slag and desulfurized gypsum, and adds porous and lightweight biochar, and prepares a new type of low-carbon, all-solid waste-based, lightweight and high-strength artificial aggregate 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 CO2 absorption and storage capabilities.

[0006] To achieve the above object, the present invention proposes a method for preparing artificial aggregate by using waste incineration fly ash, granulated blast furnace slag, desulfurized gypsum and biochar as raw materials through disc granulation technology. The present invention is achieved by the following technical solutions: The invention discloses a biochar-modified garbage incineration fly ash-based carbon-fixing artificial aggregate, wherein the artificial aggregate is a spherical aggregate with hydrated calcium aluminosilicate gel, ettringite and Freund's salt as main hydration products, wherein the raw materials used for preparing 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.

[0007] The present invention also discloses a method for preparing a biochar-modified garbage incineration fly ash-based carbon-fixing artificial aggregate, comprising 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 deionized water with 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: Add part of the mixed dry materials and deionized water in a corresponding proportion to the mixed dry materials every 2-5 minutes, and add the mixed dry materials and deionized water in a corresponding proportion to the mixed dry materials 3-5 times in total. When fresh spheres with continuous particle size distribution are produced in the disc granulator, the granulation is completed. 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: The obtained second aggregate pre-finished product is transferred into a standard curing box for standard curing for at least 28 days to obtain a finished aggregate product.

[0008] As a further improvement, the waste incineration fly ash in step S1 of the present invention is detoxified fly ash that has undergone low-temperature pyrolysis and multi-stage water washing.

[0009] As a further improvement, the biochar in step S1 of the present invention needs to be ground before mixing so that its particles are smaller than 2.36 mm.

[0010] As a further improvement, in step S2 of the present invention, the mass ratio of deionized water to the taken portion of the mixed dry material is 0.34-0.31:1.0.

[0011] As a further improvement, the mass ratio of deionized water to the mixed dry material in step S3 of the present invention is 0.24-0.22:1.0 As a further improvement, in step S4 of the present invention, after the first aggregate pre-product is screened according to the required particle size range, 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.

[0012] 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%.

[0013] The present invention provides a new approach for the safe disposal and resource utilization of waste incineration fly ash. Based on the chemical composition complementarity mechanism between different solid wastes, the composition combination is scientifically optimized, waste incineration fly ash is synergistically recycled with granulated blast furnace slag and desulfurized gypsum, and biochar is added for modification to prepare waste incineration fly ash-based carbon-fixing artificial aggregate.

[0014] Compared with the prior art, the present invention has the following characteristics and beneficial effects: (1) The raw material ratio proposed in the present invention, namely, waste incineration fly ash: granulated blast furnace slag: desulfurized gypsum: biochar = (20-25): (55-65): (10-15): (4-12), fully utilizes the characteristics of waste incineration fly ash rich in alkaline calcium salts, and cooperates with multiple sources of solid waste to prepare cold-bonded artificial aggregate, thereby achieving high-volume recovery and resource utilization of waste incineration fly ash, and has lower carbon emissions than the production process of traditional artificial aggregates; (2) The present invention innovatively proposes to use biochar to modify the waste incineration fly ash-based artificial aggregate. On the one hand, the internal curing effect of biochar is used to ensure the cylinder pressure strength of the artificial aggregate while achieving lightweight. On the other hand, based on the characteristics of high porosity and high specific surface area of ​​biochar, the absorption and storage capacity of artificial aggregate for CO2 is enhanced, giving artificial aggregate the function of carbon fixation, while further reducing carbon emissions during the production and application of artificial aggregate. (3) The present invention adopts disc granulation technology to prepare cold-bonded artificial aggregate. By selecting the appropriate disc inclination angle (45-55°) and rotation speed (40-75 r / min), an efficient process path for preparing waste incineration fly ash-based artificial aggregate is formed. At the same time, compared with the traditional high-temperature sintering preparation of artificial aggregate, the energy consumption is lower and there is no secondary pollution problem caused by the volatilization of pollutants. The overall preparation process is more green and low-carbon.

[0015] In general, compared with the traditional landfill disposal method of waste incineration fly ash, the present invention greatly reduces the land resource occupation and potential secondary environmental pollution risks caused by landfill, while realizing the resource utilization of three types of solid wastes: waste incineration fly ash, granulated blast furnace slag and desulfurized gypsum. Under the modification effect of biochar, it is converted into lightweight, high-strength carbon-fixing artificial aggregate, further reducing the demand for the mining of natural sand and gravel aggregates. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic flow chart of a method for preparing biochar-modified waste incineration fly ash-based carbon-fixing artificial aggregate proposed in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] The present invention provides a biochar-modified garbage incineration fly ash-based carbon-fixing artificial aggregate and a preparation method. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. 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.

[0018] The present invention provides a method for preparing an artificial aggregate using fly ash from garbage incineration, granulated blast furnace slag, desulfurized gypsum and biochar as main raw materials, such as Figure 1 shown.

[0019] In some specific implementations, in order to prevent the raw materials from getting damp and agglomerating, thereby causing uneven mixing, the waste incineration fly ash needs to be pre-dried before the raw materials are mixed to keep it in a uniform powder state.

[0020] The following is a further explanation of the biochar-modified garbage incineration fly ash-based carbon-fixing artificial aggregate and the preparation method thereof proposed in the present invention through specific embodiments: Example 1

[0021] A biochar-modified garbage incineration fly ash-based carbon-fixing artificial aggregate and a preparation method thereof, the specific steps are as follows: (1) Dry the waste incineration fly ash in a 60°C forced air drying oven for at least 24 h until constant weight is reached, and then remove it for subsequent use; (2) Grinding the biochar in a mortar, sieving the ground powder through an 8-mesh (2.36 mm) standard sieve, and using the sieved biochar powder as raw material for subsequent use; (3) The waste incineration fly ash, granulated blast furnace slag, desulfurized gypsum and biochar were mixed in a mass ratio of 20:65:15:4, and mixed evenly for 2 min at a speed of 200 r / min using a stirrer to obtain a mixed dry powder; (4) Weigh a portion of the mixed dry material, mix deionized water with the portion of the mixed dry material at a mass ratio of 0.34:1.0 and stir. 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° and a rotation speed of 75 r / min; (5) Add part of the mixed dry materials and deionized water in a mass ratio of 0.24:1.0 to the mixed dry materials every 4 minutes. Add the mixed dry materials and deionized water in a corresponding ratio 4 times in total. When fresh spheres with a continuous particle size distribution are produced in the disc granulator, granulation is completed. The fresh spheres are called the first aggregate pre-finished product. (6) Screening the first aggregate pre-finished product using 2.36 mm, 4.75 mm, 9.5 mm, 16 mm, and 20 mm standard sieves to obtain a second aggregate pre-finished product; (7) The obtained second aggregate pre-finished product is transferred to a standard curing box for standard curing (temperature 20 ± 2 °C, relative humidity ≥ 95%) for at least 28 days to obtain the aggregate finished product.

[0022] The obtained finished aggregate was tested for performance according to GB / T 17431.1-2010 "Lightweight Aggregates and Their Test Methods". The test results are shown in Table 1: Table 1 is the physical properties of the aggregate in Example 1

[0023] <![CDATA[Bulk density (kg / m 3 )]]> <![CDATA[Apparent density (kg / m 3 )]]> Cylinder pressure strength (MPa) 1 h water absorption rate (%) <![CDATA[CO2 absorption capacity (g / 100g)]]> Example 1 1020.2 1672.4 10.6 12.7 4.3 Example 2

[0024] A biochar-modified garbage incineration fly ash-based carbon-fixing artificial aggregate and a preparation method thereof, the specific steps are as follows: (1) Dry the waste incineration fly ash in a 60°C forced air drying oven for at least 24 h until constant weight is reached, and then remove it for subsequent use; (2) Grinding the biochar in a mortar, sieving the ground powder through an 8-mesh (2.36 mm) standard sieve, and using the sieved biochar powder as raw material for subsequent use; (3) The waste incineration fly ash, granulated blast furnace slag, desulfurized gypsum and biochar were mixed in a mass ratio of 20:65:15:8, and mixed evenly for 2 min at a speed of 200 r / min using a stirrer to obtain a mixed dry powder; (4) Weigh a portion of the mixed dry material, mix deionized water and the mixed dry material at a mass ratio of 0.32:1.0 and stir. 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° and a rotation speed of 75 r / min; (5) adding a portion of the mixed dry material and deionized water in a mass ratio of 0.22:1.0 to the portion of the mixed dry material every 4 minutes, adding the mixed dry material and deionized water in a corresponding ratio 4 times in total. When fresh spheres with a continuous particle size distribution are produced in the disc granulator, the granulation is completed. The fresh spheres are called the first aggregate pre-finished product; (6) Screening the first aggregate pre-finished product using 2.36 mm, 4.75 mm, 9.5 mm, 16 mm, and 20 mm standard sieves to obtain a second aggregate pre-finished product; (7) The obtained second aggregate pre-finished product is transferred to a standard curing box for standard curing (temperature 20 ± 2 °C, relative humidity ≥ 95%) for at least 28 days to obtain the aggregate finished product.

[0025] The obtained finished aggregate was tested for performance according to GB / T 17431.1-2010 "Lightweight Aggregates and Their Test Methods". The test results are shown in Table 2: Table 2 is the physical properties of the aggregate in Example 2 <![CDATA[Bulk density (kg / m 3 )]]> <![CDATA[Apparent density (kg / m 3 )]]> Cylinder pressure strength (MPa) 1 h water absorption rate (%) <![CDATA[CO2 absorption capacity (g / 100g)]]> Example 2 957.7 1473.4 8.2 14.4 5.5 Example 3

[0026] A biochar-modified garbage incineration fly ash-based carbon-fixing artificial aggregate and a preparation method thereof, the specific steps are as follows: (1) Dry the waste incineration fly ash in a 60°C forced air drying oven for at least 24 h until constant weight is reached, and then remove it for subsequent use; (2) Grinding the biochar in a mortar, sieving the ground powder through an 8-mesh (2.36 mm) standard sieve, and using the sieved biochar powder as raw material for subsequent use; (3) The waste incineration fly ash, granulated blast furnace slag, desulfurized gypsum and biochar were mixed in a mass ratio of 20:65:15:12, and mixed evenly for 2 min at a speed of 200 r / min using a stirrer to obtain a mixed dry powder; (4) Weigh a portion of the mixed dry material, mix deionized water with the portion of the mixed dry material at a mass ratio of 0.31:1.0 and stir. 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° and a rotation speed of 75 r / min; (5) adding a portion of the mixed dry material and deionized water in a mass ratio of 0.22:1.0 to the portion of the mixed dry material every 4 minutes, adding the mixed dry material and deionized water in a corresponding ratio 4 times in total. When fresh spheres with a continuous particle size distribution are produced in the disc granulator, the granulation is completed. The fresh spheres are called the first aggregate pre-finished product; (6) Screening the first aggregate pre-finished product using 2.36 mm, 4.75 mm, 9.5 mm, 16 mm, and 20 mm standard sieves to obtain a second aggregate pre-finished product; (7) The obtained second aggregate pre-finished product is transferred to a standard curing box for standard curing (temperature 20 ± 2 °C, relative humidity ≥ 95%) for at least 28 days to obtain the aggregate finished product.

[0027] The obtained finished aggregate was tested for performance according to GB / T 17431.1-2010 "Lightweight Aggregates and Their Test Methods". The test results are shown in Table 3: Table 3 is the physical properties of the aggregate in Example 3 <![CDATA[Bulk density (kg / m 3 ).]]> <![CDATA[Apparent density (kg / m 3 )]]> Cylinder pressure strength (MPa) 1 h water absorption rate (%) <![CDATA[CO2 absorption capacity (g / 100g)]]> Example 3 848.4 1325.7 7.3 16.3 7.1 Comparative Example 1

[0028] 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.

[0029] The operation process of this comparative example is different from that of Example 1 in that biochar is no longer added in this comparative example, and each step is adjusted as follows: (1) Dry the waste incineration fly ash in a 60°C forced air drying oven for at least 24 h until constant weight is reached, and then remove it for subsequent use; (2) Mix waste incineration fly ash, granulated blast furnace slag and desulfurized gypsum in a mass ratio of 20:65:15, and mix them evenly for 2 min under the action of a stirrer at a speed of 200 r / min to obtain a mixed dry powder; (3) Weigh a portion of the mixed dry material, mix deionized water with the portion of the mixed dry material at a mass ratio of 0.35:1.0 and stir. 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° and a rotation speed of 75 r / min; (4) adding a portion of the mixed dry material and deionized water in a mass ratio of 0.25:1.0 to the mixed dry material every 4 minutes, adding the mixed dry material and deionized water in a corresponding ratio 4 times in total. When fresh spheres with a continuous particle size distribution are produced in the disc granulator, granulation is completed. The fresh spheres are called the first aggregate pre-finished product; (5) Screening the first aggregate pre-finished product using 2.36 mm, 4.75 mm, 9.5 mm, 16 mm, and 20 mm standard sieves to obtain a second aggregate pre-finished product; (6) The obtained second aggregate pre-finished product is transferred to a standard curing box for standard curing (temperature 20 ± 2 °C, relative humidity ≥ 95%) for at least 28 days to obtain the aggregate finished product.

[0030] The obtained finished aggregate was tested for performance according to GB / T 17431.1-2010 "Lightweight Aggregates and Their Test Methods". The test results are shown in Table 4: Table 4 is the physical properties of the aggregate in Comparative Example 1 <![CDATA[Bulk density (kg / m 3 ).]]> <![CDATA[Apparent density (kg / m 3 )]]> Cylinder pressure strength (MPa) 1 h water absorption rate (%) <![CDATA[CO2 absorption capacity (g / 100g)]]> Comparative Example 1 1117.7 1774.2 8.7 11.2 3.2 Through the comparative analysis between comparative example 1 and examples 1, 2 and 3, it can be found that with the increase of biochar content, the bulk density of artificial aggregate is greatly improved, from 1117.7 kg / m 3 The value was reduced to 848.4 kg / m in Example 3. 3 . Generally speaking, the bulk density and cylinder compressive strength of aggregate are two contradictory indicators. However, due to the internal curing effect of biochar, after adding an appropriate amount of biochar, the cylinder compressive strength of artificial aggregate increased from 8.7 MPa in Comparative Example 1 to 10.6 MPa in Example 1. Then, with the increase of biochar dosage, the cylinder compressive strength of artificial aggregate was adversely affected. At the same time, the high porosity of biochar and its high affinity for non-polar compounds give artificial aggregate a stronger CO2 absorption capacity. With the increase of biochar dosage, the CO2 absorption capacity of artificial aggregate increased from 3.2 g / 100g in Comparative Example 1 to 7.1 g / 100g in Example 3. In general, biochar has an excellent effect on improving the bulk density and CO2 absorption capacity of artificial aggregates. However, excessive biochar incorporation will significantly weaken the mechanical properties of artificial aggregates. Therefore, when using biochar to modify artificial aggregates, it is necessary to control the amount of biochar added to reduce the bulk density while ensuring the mechanical properties of artificial aggregates, thereby achieving the preparation of lightweight, high-strength, carbon-fixing artificial aggregates.

[0031] The above are only preferred embodiments of the present invention. Although the present invention has been disclosed as a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with the art can use the above disclosed methods and technical contents to make many possible changes and modifications to the technical solution of the present invention without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution 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, calcium sulfonate and Freund's salt as the main hydration products. 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.

2. A method for preparing biochar-modified waste incineration fly ash-based carbon-fixing artificial aggregate, characterized in that: The following steps are involved: 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 a portion of the mixed dry material, mix and stir the deionized water with the portion 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: The obtained second aggregate pre-finished product is transferred into a standard curing box for standard curing for at least 28 days to obtain a finished aggregate product.

3. The method for preparing biochar-modified garbage incineration fly ash-based carbon-fixing artificial aggregate according to claim 2, characterized in that: The waste incineration fly ash in step S1 is detoxified fly ash that has been subjected to low-temperature pyrolysis and multi-stage water washing.

4. The method for preparing biochar-modified garbage incineration fly ash-based carbon-fixing artificial aggregate according to claim 2 or 3, characterized in that: The biochar in step S1 needs to be ground before mixing so that its particles are smaller than 2.36 mm.

5. The method for preparing biochar-modified garbage incineration fly ash-based carbon-fixing artificial aggregate according to claim 4, characterized in that: In the step S2, the mass ratio of deionized water to the mixed dry material is 0.34-0.31:1.

0.

6. The method for preparing the biochar-modified garbage incineration fly ash-based carbon-fixing artificial aggregate according to claim 2, 3 or 5, characterized in that: In the step S3, the mass ratio of deionized water to the mixed dry material is 0.24-0.22:1.

0.

7. The method for preparing biochar-modified garbage incineration fly ash-based carbon-fixing artificial aggregate according to claim 6, characterized in that: In the step S4, the first aggregate pre-product is screened according to the required particle size range, and 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.

8. The method for preparing biochar-modified garbage incineration fly ash-based carbon-fixing artificial aggregate according to claim 7, characterized in that: The standard curing conditions in step S5 are a temperature of 20 ± 2 °C and a relative humidity of ≥ 95%.

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