A green, low-carbon and functional coal gangue lightweight aggregate

Abstract

The present invention discloses a green and low-carbon functional coal gangue lightweight aggregate, belonging to the technical field of lightweight aggregates for construction. The coal gangue lightweight aggregate comprises the following raw materials in parts by weight: 86.4 - 89.1 parts of coal gangue, 9.6 - 9.9 parts of fly ash, 1 - 4 parts of pore-forming agent, and 6 - 7 parts of sodium silicate solution; the pore-forming agent is composed of calcium carbonate, manganese dioxide, and lanthanum zirconium metal-organic framework, and the mass ratio of calcium carbonate, manganese dioxide, and lanthanum zirconium metal-organic framework is 1:1:1 - 2; the present invention uses industrial solid waste coal gangue as the main raw material, fly ash as the auxiliary raw material, and in combination with the use of a pore-forming agent, to obtain a lightweight and high-strength coal gangue lightweight aggregate. Among them, the utilization rate of coal gangue is more than 80%, providing a new path for the large-scale resource utilization of solid waste coal gangue and the high-performance preparation of lightweight aggregates.

Description

Technical Field

[0001] The present invention belongs to the technical field of lightweight aggregates for construction, and particularly relates to a green, low-carbon and functional coal gangue lightweight aggregate. Background Art

[0002] Lightweight aggregates play a role of skeleton and filling in concrete, accounting for about 70% of the total volume of concrete. Lightweight aggregates have a significant impact on the workability, mechanical properties, volume stability and durability of concrete, and are an important part of concrete. Previously, lightweight aggregates used in concrete were mostly made from natural materials such as shale and clay. Since these natural materials are non-renewable resources, their mining has been prohibited or restricted.

[0003] The main components of coal gangue are SiO2 and Al2O3, and are accompanied by flux oxides such as Fe2O3, CaO, MgO, K2O, and Na2O, which are extremely similar to the chemical composition range of raw materials for producing lightweight aggregates. Among them, acidic oxides SiO2 and Al2O3 will form crystal phases such as mullite at high temperatures to improve the strength of lightweight aggregates, and basic oxides Fe2O3, CaO, MgO, K2O, and Na2O play a role in reducing the sintering temperature of lightweight aggregates. In addition, iron oxide and carbon can also be used as gas-generating components to provide a material basis for the formation of pore structures inside lightweight aggregates. Therefore, using coal gangue to produce lightweight aggregates can, on the one hand, make up for the shortage of natural lightweight aggregate resources, and on the other hand, can achieve the large-scale utilization of solid waste coal gangue.

[0004] There are generally two treatment methods for using coal gangue as lightweight aggregates for concrete. One is to crush and screen coal gangue and directly (after heat treatment) use it as lightweight aggregates to prepare concrete. The other is to crush and grind coal gangue into coal gangue powder, and then optimize the raw material ratio and sinter it to obtain coal gangue ceramsite for use in concrete. However, directly using crushed coal gangue blocks as lightweight aggregates has the disadvantages of low strength and high water absorption, and is mostly used to prepare concrete with a relatively low strength grade, which also results in a low utilization rate. Therefore, the preparation of lightweight aggregate ceramsite from coal gangue is a current research hotspot.

[0005] The authorized announcement number CN106904938B discloses a high-strength ceramsite using coal gangue as raw material and fuel, including the following raw material components by mass percentage: 80-95% of coal gangue, 4.5-16% of feldspar, 0-5% of limestone, and 0.1-0.5% of foaming agent. The incorporation amount of coal gangue reaches 80-95%, but the obtained ceramsite has a relatively low cylinder compressive strength (6-10 MPa). Summary of the Invention

[0006] The purpose of the present invention is to provide a green, low-carbon and functional coal gangue lightweight aggregate to solve the problem of low cylinder compressive strength of existing coal gangue ceramsite.

[0007] The object of the present invention can be achieved by the following technical solutions:

[0008] A green and low-carbon functional coal gangue lightweight aggregate, comprising the following raw materials in parts by weight: 86.4 - 89.1 parts of coal gangue, 9.6 - 9.9 parts of fly ash, 1 - 4 parts of pore-forming agent, and 6 - 7 parts of sodium silicate solution.

[0009] Further, the coal gangue contains 50 - 70% of silicon oxide, 10 - 25% of aluminum oxide, 1 - 5% of iron oxide, and 4 - 15% of loss on ignition.

[0010] Further, the fly ash contains 50 - 70% of silicon oxide, 15 - 30% of aluminum oxide, 1 - 5% of iron oxide, and 0.5 - 2% of loss on ignition.

[0011] Further, the pore-forming agent is composed of calcium carbonate, manganese dioxide, and lanthanum zirconium metal-organic framework, and the mass ratio of calcium carbonate, manganese dioxide, and lanthanum zirconium metal-organic framework is 1:1:1 - 2.

[0012] Further, the concentration of the sodium silicate solution is 1 - 2%, and the modulus of the sodium silicate is 2.6 - 3.0.

[0013] Further, the lanthanum zirconium metal-organic framework is prepared by the following steps:

[0014] Mix La(NO3)3·6H2O, Zr(NO3)4·5H2O, and 1,3,5-benzenetricarboxylic acid evenly, add them to DMF, stir at a speed of 500 - 1000 r / min for 30 min, then transfer to a polytetrafluoroethylene reaction kettle, treat at 180 °C for 24 h, after centrifugal filtration, collect the precipitate, wash the precipitate three times with DMF and absolute ethanol respectively, and finally dry in an oven at 60 °C to obtain the lanthanum zirconium metal-organic framework.

[0015] Further, the dosage ratio of La(NO3)3·6H2O, Zr(NO3)4·5H2O, 1,3,5-benzenetricarboxylic acid, and DMF is X mmol:Y mmol:3 mmol:60 mL, X≥0, Y≥0, and X + Y = 6.

[0016] The above green and low-carbon functional coal gangue lightweight aggregate is prepared by the following steps:

[0017] S1. Crush and ball-mill the coal gangue through a 100-mesh sieve to obtain coal gangue powder;

[0018] S2. According to the ratio, put coal gangue powder, fly ash, and pore-forming agent into a mixer, mix them evenly to obtain a mixture, transfer the mixture to a pelletizing machine or a pair-roll granulator, and spray a sodium silicate solution to make green pellets. The diameter of the green pellets prepared by the pelletizing machine is 0.16 - 8 mm, and the diameter of the green pellets prepared by the pair-roll granulator is 8 - 25 mm;

[0019] S3. Dry the green pellets at 200 °C for 1 h, then carry out pre-calcination and calcination. After the calcination is completed, cool down to 400 °C at a cooling rate of 5 °C / min, and then cool down to room temperature with the furnace, thus obtaining the green and low-carbon functional coal gangue lightweight aggregate.

[0020] Furthermore, the pre-calcination temperature is 480 - 520 °C, the pre-calcination time is 40 - 50 min, and the heating rate in the pre-calcination stage is 5 °C / min.

[0021] Furthermore, the calcination temperature is 1050 - 1250 °C, the calcination time is 60 - 90 min, and the heating rate in the calcination stage is 5 °C / min.

[0022] Advantages of the present invention:

[0023] The present invention provides a green and low-carbon functional coal gangue lightweight aggregate. "Green" means that the main raw material is coal gangue, which is a recycled aggregate with zero or low carbon content. "Functional" means lightweight, high strength, sound insulation, heat insulation, earthquake resistance, impermeability, and high temperature resistance. Specifically, this lightweight aggregate uses industrial solid waste coal gangue as the main raw material, fly ash as the auxiliary raw material, and with the use of a pore-forming agent, to obtain a lightweight and high-strength coal gangue lightweight aggregate. Among them, the utilization rate of coal gangue is over 80%, providing a new path for the large-scale resource utilization of solid waste coal gangue and the high-performance preparation of lightweight aggregates.

[0024] The present invention uses a composite pore-forming agent, which is specifically composed of a compound of calcium carbonate, manganese dioxide, and lanthanum zirconium metal-organic framework. The three work together to play a pore-forming role. Manganese dioxide undergoes an oxidation-reduction reaction during roasting to generate gas, which produces an expansion stress on the aggregate body. Calcium carbonate decomposes to produce carbon dioxide gas during sintering, and these gases form pores inside the ceramsite. After roasting, the lanthanum zirconium metal-organic framework will form a porous carbon network skeleton, which fills between the aggregate particles with its good dispersibility, helping to improve the cylinder compressive strength and porosity of the ceramsite. In addition, after roasting, the lanthanum zirconium metal-organic framework will also produce zirconium oxide and lanthanum oxide. Zirconium oxide is a material with high hardness and high strength. When it is introduced into coal gangue ceramsite, it can further improve the mechanical properties of the ceramsite, including its cylinder compressive strength. Lanthanum oxide is a rare earth oxide that can reduce the sintering temperature and promote the formation of mullite inside the ceramsite, significantly improving the mechanical properties of the ceramsite.

[0025] In the present invention, a water glass solution is used as a thickening agent. At high temperature, the water glass fills the micro-cracks between the internal pores of the ceramsite, making the ceramsite more dense, reducing the water absorption rate of the ceramsite. The addition of water glass provides the plasticity of the raw materials, changes the structure of the voids, and the original large pores become micro-fine pores, which not only provides the strength of the ceramsite but also reduces the water absorption rate of the ceramsite. Detailed implementation manners

[0026] The following will describe clearly and completely the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0027] The composition and source of some raw materials used in this application are as follows:

[0028] Coal gangue, sourced from Huainan Dongchen Solid Waste Co., Ltd., with a specific surface area ≥ 400 m 2 / kg, and the proportion of main chemical components is: 54.91 wt% SiO2, 22.46 wt% Al2O3, 4.16 wt% Fe2O3, 2.26 wt% CaO, 0.491 wt% MgO, 1.71 wt% K2O, 0.47 wt% Na2O, 13.31 wt% LOI.

[0029] Fly ash, sourced from Tianjin Zhicheng New Material Technology Co., Ltd., and the proportion of main chemical components is: 52.00 wt% SiO2, 22.00 wt% Al2O3, 4.00 wt% Fe2O3, 0.56 wt% MgO, 12.0 wt% CaO, 0.43 wt% Na2O, 0.35 wt% SO3, 1 wt% LOI.

[0030] Preparation Example 1

[0031] A lanthanum zirconium metal-organic framework is prepared through the following steps:

[0032] 3 mmol of La(NO3)3·6H2O, 3 mmol of Zr(NO3)4·5H2O and 3 mmol of 1,3,5-benzenetricarboxylic acid are mixed evenly and then added to 60 mL of DMF. After stirring at a rotation speed of 500 r / min for 30 min, it is transferred to a polytetrafluoroethylene reaction kettle and treated at 180 °C for 24 h. After centrifugal filtration, the precipitate is collected. The precipitate is washed three times with DMF and absolute ethanol respectively, and finally dried in an oven at 60 °C to obtain the lanthanum zirconium metal-organic framework.

[0033] Preparation Example 2

[0034] A lanthanum-zirconium metal-organic framework is prepared by the following steps:

[0035] Mix 1 mmol La(NO3)3·6H2O, 5 mmol Zr(NO3)4·5H2O and 3 mmol 1,3,5-benzenetricarboxylic acid evenly, add them to 60 mL of DMF, stir at a speed of 800 r / min for 30 min, then transfer to a polytetrafluoroethylene reaction kettle, treat at 180 °C for 24 h, after centrifugal filtration, collect the precipitate, wash the precipitate three times with DMF and absolute ethanol respectively, and finally dry it in an oven at 60 °C to obtain the lanthanum-zirconium metal-organic framework.

[0036] Preparation Example 3

[0037] A lanthanum-zirconium metal-organic framework is prepared by the following steps:

[0038] Mix 5 mmol La(NO3)3·6H2O, 1 mmol Zr(NO3)4·5H2O and 3 mmol 1,3,5-benzenetricarboxylic acid evenly, add them to 60 mL of DMF, stir at a speed of 1000 r / min for 30 min, then transfer to a polytetrafluoroethylene reaction kettle, treat at 180 °C for 24 h, after centrifugal filtration, collect the precipitate, wash the precipitate three times with DMF and absolute ethanol respectively, and finally dry it in an oven at 60 °C to obtain the lanthanum-zirconium metal-organic framework.

[0039] Control Example 1

[0040] A lanthanum metal-organic framework is prepared by the following steps:

[0041] Mix 6 mmol La(NO3)3·6H2O and 3 mmol 1,3,5-benzenetricarboxylic acid evenly, add them to 60 mL of DMF, stir at a speed of 500 r / min for 30 min, then transfer to a polytetrafluoroethylene reaction kettle, treat at 180 °C for 24 h, after centrifugal filtration, collect the precipitate, wash the precipitate three times with DMF and absolute ethanol respectively, and finally dry it in an oven at 60 °C to obtain the lanthanum-zirconium metal-organic framework.

[0042] Control Example 2

[0043] A zirconium metal-organic framework is prepared by the following steps:

[0044] 6 mmol of Zr(NO3)4·5H2O and 3 mmol of 1,3,5-benzenetricarboxylic acid were mixed evenly and then added to 60 mL of DMF. After stirring at 1000 r / min for 30 min, the mixture was transferred to a polytetrafluoroethylene reaction kettle and treated at 180 °C for 24 h. After centrifugation and filtration, the precipitate was collected, washed three times with DMF and anhydrous ethanol respectively, and finally dried in an oven at 60 °C to obtain the lanthanum zirconium metal-organic framework.

[0045] Example 1

[0046] A green and low-carbon functional coal gangue lightweight aggregate comprises the following raw materials in parts by weight: 86.4 parts of coal gangue, 9.6 parts of fly ash, 4 parts of pore-forming agent, and 6 parts of sodium silicate solution.

[0047] The pore-forming agent is composed of calcium carbonate, manganese dioxide, and the lanthanum zirconium metal-organic framework prepared in Preparation Example 1, and the mass ratio of calcium carbonate, manganese dioxide, and the lanthanum zirconium metal-organic framework is 1:1:1.

[0048] The concentration of the sodium silicate solution is 1%, and the modulus of the sodium silicate is 2.6.

[0049] The above green and low-carbon functional coal gangue lightweight aggregate is prepared by the following steps:

[0050] S1. The coal gangue was crushed and ball-milled through a 100-mesh sieve to obtain coal gangue powder.

[0051] S2. According to the ratio, the coal gangue powder, fly ash, and pore-forming agent were placed in a mixer and mixed evenly to obtain a mixture. The mixture was transferred to a pelletizing machine, and the rotation speed of the pelletizing machine was controlled at 60 r / min. While the pelletizing machine was rotating, the sodium silicate solution was sprayed onto the mixture to granulate and form pellets, and the particle size of the green pellets was controlled at 0.16 - 8 mm.

[0052] S3. The green pellets were dried at 200 °C for 1 h, then heated to 500 °C at a heating rate of 5 °C / min for pre-calcination, the pre-calcination time was 40 min, then heated to 1070 °C at a heating rate of 5 °C / min for calcination, the calcination time was 80 min, and after the calcination was completed, it was cooled to 400 °C at a cooling rate of 5 °C / min, and then cooled to room temperature in the furnace to obtain the green and low-carbon functional coal gangue lightweight aggregate.

[0053] Example 2

[0054] A green and low-carbon functional coal gangue lightweight aggregate comprises the following raw materials in parts by weight: 88.2 parts of coal gangue, 9.8 parts of fly ash, 2 parts of pore-forming agent, and 6.5 parts of sodium silicate solution.

[0055] The pore-forming agent consists of calcium carbonate, manganese dioxide, and the lanthanum-zirconium metal-organic framework of Preparation Example 2. The mass ratio of calcium carbonate, manganese dioxide, and the lanthanum-zirconium metal-organic framework is 1:1:1.5.

[0056] The concentration of the sodium silicate solution is 1.5%, and the modulus of the sodium silicate is 2.8.

[0057] The above green and low-carbon functional coal gangue lightweight aggregate is prepared through the following steps:

[0058] S1. Crush and ball-mill the coal gangue through a 100-mesh sieve to obtain coal gangue powder;

[0059] S2. According to the ratio, put the coal gangue powder, fly ash, and pore-forming agent into a mixer, mix evenly to obtain a mixture, transfer the mixture to a pelletizing machine, control the rotation speed of the pelletizing machine at 60 r / min, spray the sodium silicate solution onto the mixture while the pelletizing machine is rotating to granulate and form pellets, and control the particle size of the green pellets at 0.16 - 8 mm;

[0060] S3. Dry the green pellets at 200°C for 1 h, then heat them at a heating rate of 5°C / min to 480°C for pre-calcination, with the pre-calcination time being 50 min, then heat them at a heating rate of 5°C / min to 1050°C for calcination, with the calcination time being 60 min. After the calcination is completed, cool them at a cooling rate of 5°C / min to 400°C, and then cool them to room temperature with the furnace, thus obtaining the green and low-carbon functional coal gangue lightweight aggregate.

[0061] Example 3

[0062] A green and low-carbon functional coal gangue lightweight aggregate, comprising the following raw materials in parts by weight: 89.1 parts of coal gangue, 9.9 parts of fly ash, 1 part of pore-forming agent, and 7 parts of sodium silicate solution.

[0063] The pore-forming agent consists of calcium carbonate, manganese dioxide, and the lanthanum-zirconium metal-organic framework of Preparation Example 3. The mass ratio of calcium carbonate, manganese dioxide, and the lanthanum-zirconium metal-organic framework is 1:1:2.

[0064] The concentration of the sodium silicate solution is 2%, and the modulus of the sodium silicate is 3.0.

[0065] The above green and low-carbon functional coal gangue lightweight aggregate is prepared through the following steps:

[0066] S1. Crush and ball-mill the coal gangue through a 100-mesh sieve to obtain coal gangue powder;

[0067] S2. According to the ratio, put coal gangue powder, fly ash, and pore-forming agent into a mixer, mix evenly to obtain a mixture, transfer the mixture to a pelletizing machine, control the rotation speed of the pelletizing machine at 60 r / min, spray sodium silicate solution onto the mixture while the pelletizing machine is rotating to granulate and form pellets, and control the particle size of the green pellets to be 0.16 - 8 mm;

[0068] S3. Dry the green pellets at 200 °C for 1 h, then heat them up to 520 °C at a heating rate of 5 °C / min for pre-calcination, with a pre-calcination time of 50 min, then heat them up to 1100 °C at a heating rate of 5 °C / min for calcination, with a calcination time of 90 min. After the calcination is completed, cool them down to 400 °C at a cooling rate of 5 °C / min, and then cool them down to room temperature in the furnace to obtain the green low-carbon functional coal gangue lightweight aggregate.

[0069] Comparative Example 1

[0070] A green low-carbon functional coal gangue lightweight aggregate, the difference in the raw material composition compared with Example 1 is that the lanthanum-zirconium metal-organic framework in the pore-forming agent of Example 1 is replaced with the product prepared in Comparative Example 1, and the other raw materials, parameters, and processes are the same as those in Example 1.

[0071] Comparative Example 2

[0072] A green low-carbon functional coal gangue lightweight aggregate, the difference in the raw material composition compared with Example 1 is that the lanthanum-zirconium metal-organic framework in the pore-forming agent of Example 1 is replaced with the product prepared in Comparative Example 2, and the other raw materials, parameters, and processes are the same as those in Example 1.

[0073] Comparative Example 3

[0074] A green low-carbon functional coal gangue lightweight aggregate, the difference in the raw material composition compared with Example 1 is that the pore-forming agent is composed of calcium carbonate and manganese dioxide in a mass ratio of 1:1, and the other raw materials, parameters, and processes are the same as those in Example 1.

[0075] Comparative Example 4

[0076] A green low-carbon functional coal gangue lightweight aggregate, the difference in the raw material composition compared with Example 1 is that the pore-forming agent is composed of calcium carbonate and the lanthanum-zirconium metal-organic framework of Preparation Example 1 in a mass ratio of 1:1, and the other raw materials, parameters, and processes are the same as those in Example 1.

[0077] Comparative Example 5

[0078] A green low-carbon functional coal gangue lightweight aggregate, the difference in the raw material composition compared with Example 1 is that the pore-forming agent is composed of manganese dioxide and the lanthanum-zirconium metal-organic framework of Preparation Example 1 in a mass ratio of 1:1, and the other raw materials, parameters, and processes are the same as those in Example 1.

[0079] The coal gangue lightweight aggregates obtained from Examples 1 - 3 and Comparative Examples 1 - 5 were tested, and the testing process is as follows:

[0080] (1) The bulk density and cylinder compressive strength were tested in accordance with the specification requirements of GB / T17431.2 - 2010 "Test Methods for Lightweight Aggregates".

[0081] (2) The water absorption rate of the lightweight aggregates was measured using the tea - bag method. First, three portions of 500 g of lightweight aggregates were weighed for each group, dried in an oven until constant weight, and then weighed. Then they were placed in tea - bags and fully immersed in tap water, and left standing for 24 h under constant temperature conditions. After taking them out and placing them on a towel and blowing them with a hair dryer to the saturated surface - dry state, they were weighed again. The water absorption rate was calculated according to the following formula:

[0082] W=(m1 - m0) / m0×100%, where W is the water absorption rate of the lightweight aggregates, %; m1 is the mass of the aggregates in the saturated surface - dry state, g; m0 is the mass of the dried aggregates, g, and finally the average value was taken.

[0083] The test results are shown in Table 1:

[0084] Table 1

[0085]

[0086] It can be seen from the data recorded in Table 1 that the bulk density of the coal gangue lightweight aggregates obtained from Examples 1 - 3 is 950 - 989 kg / m 3 , the cylinder compressive strength ≥ 17.0 MPa, and the water absorption rate is about 10%. The comprehensive performance is significantly better than that of Comparative Examples 1 - 5, indicating that the coal gangue lightweight aggregates prepared by the present invention have the characteristics of light weight, high strength, and appropriate water absorption rate.

[0087] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non - exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0088] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A green and low-carbon functional coal gangue light aggregate, characterized in that: The method comprises the following raw materials in parts by weight: 86.4-89.1 parts of coal gangue, 9.6-9.9 parts of fly ash, 1-4 parts of pore-forming agent, and 6-7 parts of water glass solution; the pore-forming agent is composed of calcium carbonate, manganese dioxide, and lanthanum zirconium metal organic framework, and the mass ratio of calcium carbonate, manganese dioxide, and lanthanum zirconium metal organic framework is 1:1:1-2; The lanthanum zirconium metal organic framework was prepared by the following steps: La(NO3)3·6H2O, Zr(NO3)4·5H2O and 1,3,5-trimethylbenzene carboxylic acid were mixed evenly and added into DMF, stirred for 30 min and then transferred into a polytetrafluoroethylene reactor, treated at 180°C for 24 h, centrifuged and filtered, and the precipitate was collected, washed and dried to obtain a lanthanum zirconium metal organic framework. The usage ratio of La(NO3)3·6H2O, Zr(NO3)4·5H2O, 1,3,5-tricarboxylic acid and DMF is Xmmol:Ymmol:3mmol:60mL, X>0, Y>0, and X+Y=6.

2. The green, low-carbon functional coal gangue light aggregate according to claim 1, characterized in that: The silicon oxide content in coal gangue is 50-70%, the aluminum oxide content is 10-25%, the iron oxide content is 1-5%, and the loss on ignition is 4-15%.

3. The green, low-carbon functional coal gangue light aggregate according to claim 1, characterized in that: The silicon oxide content in fly ash is 50-70%, the aluminum oxide content is 15-30%, the iron oxide content is 1-5%, and the loss on ignition is 0.5-2%.

4. The green, low-carbon functional coal gangue light aggregate according to claim 1, characterized in that: The green low-carbon functional coal gangue lightweight aggregate is prepared by the following steps: S1, crushing the coal gangue, ball-milling and passing through a 100-mesh sieve to obtain coal gangue powder; S2. According to the proportion, put the gangue powder, fly ash and pore-forming agent in a mixer, mix them evenly to obtain a mixture, transfer the mixture to a ball-forming machine or a double-roll granulator, spray the water glass solution to form raw balls, the diameter of the raw balls prepared by the ball-forming machine is 0.16-8mm, and the diameter of the raw balls prepared by the double-roll granulator is 8-25mm; S3. Dry the raw material balls at 200°C for 1 hour, and then pre-burn and calcine them. After calcination, cool them to 400°C at a cooling rate of 5°C / min, and then cool them to room temperature with the furnace to obtain green and low-carbon functional coal gangue light aggregate.

5. The green, low-carbon functional coal gangue light aggregate according to claim 1, characterized in that: The pre-burning temperature is 480-520°C, the pre-burning time is 40-50min, and the heating rate in the pre-burning stage is 5°C / min.

6. The green, low-carbon functional coal gangue light aggregate according to claim 1, characterized in that: The calcination temperature is 1050-1250°C, the calcination time is 60-90min, and the heating rate in the calcination stage is 5°C / min.

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