Method for coal gangue high-temperature calcination enhancement and activation

Abstract

The application discloses a kind of coal gangue high-temperature calcination enhanced activation methods, including that coal gangue is broken and screened and iron removal operation is carried out to obtain coal gangue broken material, according to coal gangue broken material chemical composition adds lignite powder to obtain coal gangue calcining material, fitting three-stage calcining temperature model obtains calcining process temperature, determines each stage design calcining time to coal gangue calcining material is calcined, simultaneously according to calcining process temperature and calcining time dynamic control oxygen concentration completes calcining, using phase change medium to the rapid quenching of coal gangue calcining product, after coal gangue calcining product cooling carries out activity regulation and control to obtain coal gangue product.This method can solve the problem of uneven activity caused by raw material fluctuation, improve calcining efficiency and calcining product quality, to realize the industrialization, stabilization and high-end of coal gangue resource utilization provides reliable technical support.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, and in particular to a method for enhancing the activation of coal gangue through high-temperature calcination. Background Technology

[0002] Coal gangue is a major solid waste generated during coal mining and washing. Its large-scale stockpiling not only occupies land but also causes environmental pollution. Calcining coal gangue at high temperatures to prepare admixtures with pozzolanic activity to replace part of the cement is an effective way to dispose of coal gangue on a large scale. This can achieve high-value-added resource utilization of coal gangue and promote the green development of the coal industry.

[0003] Currently, the calcination activation of coal gangue generally adopts a process of continuous calcination at a fixed temperature (800-1000℃) for 1-2 hours. However, this traditional method has obvious drawbacks: First, the composition of coal gangue is complex and variable, and the fixed calcination regime cannot adapt to the differences between different batches of raw materials, resulting in insufficient activation or over-calcination of the material, leading to large fluctuations in the activity and unstable quality of the calcined product. Second, the oxygen in the furnace is not effectively controlled during the calcination process, causing the carbonaceous components to burn out prematurely and fail to utilize their heat of combustion, resulting in high energy consumption and hindering the formation of the target active phase. Finally, traditional cooling methods (such as furnace cooling or simple water quenching) have slow or uneven cooling rates, causing the active metastable phase at high temperatures to recrystallize during the cooling process, generating inert crystals, which leads to a decrease in product activity, i.e., "activity quenching". Therefore, this invention proposes a method for enhancing the activation of coal gangue through high-temperature calcination. By integrating intelligent carbon blending, multi-stage dynamic calcination and rapid quenching, the method can adapt to the raw material composition, precisely control the calcination process and effectively maintain the high activity of coal gangue during calcination. This method has significant economic and environmental benefits for reducing carbon emissions in the building materials industry and replacing traditional cement clinker. Summary of the Invention

[0004] The purpose of this invention is to provide a method for enhancing and activating coal gangue through high-temperature calcination.

[0005] To achieve the above objectives, the present invention is implemented according to the following technical solution:

[0006] This invention includes the following steps:

[0007] Coal gangue is crushed, screened, and magnetically separated to remove iron to obtain coal gangue fragments. The chemical composition of the coal gangue fragments is determined, and lignite powder is added according to the chemical composition of the coal gangue fragments to obtain coal gangue calcined feed.

[0008] Calcination experimental data of different coal gangue were obtained, and a three-stage calcination temperature model was fitted. The chemical composition of the coal gangue to be calcined was input into the three-stage calcination temperature model to obtain the calcination process temperature.

[0009] The coal gangue calcined material to be calcined was calcined according to the calcination process temperature. The design calcination time for each stage was determined and the coal gangue calcined material was calcined. The oxygen concentration was dynamically controlled according to the calcination process temperature and calcination time to complete the calcination.

[0010] The coal gangue calcination product was rapidly quenched using a phase change medium, and the activity was adjusted after the coal gangue calcination product cooled to obtain the coal gangue product.

[0011] The chemical composition includes carbon content, SiO2 content, Al2O3 content, and Fe2O3 content;

[0012] The calcination experimental data includes thermal analysis experimental data and X-ray diffraction phase analysis data.

[0013] Furthermore, the method for obtaining coal gangue calcined feed includes:

[0014] The chemical composition of the coal gangue fragments was determined by X-ray diffraction phase analysis. The amount of lignite powder to be added was calculated based on the carbon content of the coal gangue fragments, using the following formula:

[0015] ;

[0016] in This refers to the amount of lignite powder added. For the target carbon content, Carbon content of coal gangue crushed material The bulk density of lignite powder, The moisture content of lignite powder. For the quality of the coal gangue fragments to be processed, This is the correction factor for calorific value fluctuation.

[0017] Furthermore, the method for fitting the three-stage calcination temperature model includes:

[0018] Calcination experiments were conducted on different coal gangues to obtain thermal analysis data and X-ray diffraction phase analysis data, and the calcination temperature of different coal gangues was determined. The specific method is as follows:

[0019] The peak temperature of hydroxyl removal from kaolinite was taken as the calcination temperature of the dehydration stage; the temperature at which kaolinite transforms into metakaolinite and carbonate minerals decompose was taken as the calcination temperature of the decomposition and crystal transformation stage; and the temperature at which the glass phase forms the fastest was taken as the calcination temperature of the activation sintering stage.

[0020] The chemical composition of different coal gangues was determined, and a three-stage calcination temperature model was obtained by linear fitting of the calcination process temperatures of different coal gangues. The expression is as follows:

[0021] ;

[0022] in for Calcination temperature at each stage, calcination stage index It includes the dehydration stage, the decomposition and crystal transformation stage, and the activation sintering stage. for Stage reference calcination temperature, The first activation coefficient, The second activation coefficient, The mass of SiO2 in the raw material. The mass of Al2O3 in the raw material. The Fe2O3 content in the raw materials This is a reference value for the mass ratio of SiO2 to Al2O3 in the regional raw materials. This is a reference value for the Fe2O3 content of the raw materials in the region.

[0023] Furthermore, the method for dynamically controlling the oxygen concentration based on the calcination process temperature and calcination time includes:

[0024] The chemical composition of the coal gangue calcined material to be calcined is input into the three-stage calcination temperature model to obtain the calcination process temperature;

[0025] Calcination tests were conducted on the coal gangue to be calcined according to the calcination process temperature. The design calcination time for each stage was determined based on the calcination test data. The specific method is as follows:

[0026] The mass loss curve of coal gangue was determined by thermogravimetric analysis (TG) curve. Dehydration was considered complete when the mass loss rate dropped to 5% of the initial rate, and the designed calcination time for the dehydration stage of coal gangue was obtained. When the intensity of the characteristic peak of kaolinite in the XRD pattern dropped to less than 3% of the original intensity, the crystal transformation was considered complete, and the designed calcination time for the decomposition and crystal transformation stage of coal gangue was obtained. When the change rate of the amorphous diffuse peak area in the XRD pattern was less than 0.3% / min, the activation was considered complete, and the designed calcination time for the activation and sintering stage of coal gangue was obtained.

[0027] Calcination is carried out according to the calcination process temperature and the designed calcination time for each stage. The oxygen concentration is adjusted by measuring the actual calcination temperature in the furnace. The specific operation is as follows:

[0028] When the actual calcination temperature in the furnace is less than the first temperature threshold and the calcination time is less than the first time threshold, maintain the standard fan power; when the actual calcination temperature in the furnace is greater than the second temperature threshold and the calcination time is greater than the second time threshold, turn off the fan; otherwise, increase the fan power.

[0029] Furthermore, the phase transformation medium for rapid quenching is specifically a molten salt bath at 280±20℃; the molten salt bath is composed of a mixture of NaNO3 and KNO3 with a melting point of 220℃.

[0030] Furthermore, the specific steps for the activity regulation are as follows: the cooled coal gangue calcination product is ultrasonically treated in a weakly alkaline buffer solution for 30 minutes; the pH range of the weakly alkaline buffer solution is 8.5-9.0.

[0031] The beneficial effects of this invention are:

[0032] This invention provides a method for enhancing and activating coal gangue through high-temperature calcination. Compared with existing technologies, this invention has the following technical advantages:

[0033] This invention, through dynamic coal blending, multi-stage heating and calcination, dynamic oxygen concentration control, rapid quenching with phase change media, and activity regulation steps, can significantly improve the activation effect and ensure stable product performance during high-temperature calcination of coal gangue. It can ensure the heat source while preventing energy waste, thereby reducing energy consumption and improving the economic efficiency of the entire calcination process. It solves the problem of "activity quenching" caused by traditional cooling methods, reduces the negative impact of harmful impurities and ineffective waste gas emissions, and is more environmentally friendly. It can realize the high-value-added resource utilization of coal gangue and promote the green development of the coal industry. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating the steps of a method for enhancing and activating coal gangue through high-temperature calcination according to the present invention. Detailed Implementation

[0035] The present invention will be further described below through specific embodiments. The illustrative embodiments and descriptions herein are used to explain the present invention, but are not intended to limit the present invention.

[0036] The present invention discloses a method for enhancing and activating coal gangue through high-temperature calcination, comprising the following steps:

[0037] like Figure 1 As shown, this embodiment includes the following steps:

[0038] Coal gangue is crushed, screened, and magnetically separated to remove iron to obtain coal gangue crushed material. The chemical composition of the coal gangue crushed material is determined, and lignite powder is added according to the chemical composition of the coal gangue crushed material to obtain coal gangue calcined material.

[0039] Calcination experimental data of different coal gangue were obtained, and a three-stage calcination temperature model was fitted. The chemical composition of the coal gangue to be calcined was input into the three-stage calcination temperature model to obtain the calcination process temperature.

[0040] The coal gangue calcined material to be calcined was calcined according to the calcination process temperature. The design calcination time for each stage was determined and the coal gangue calcined material was calcined. The oxygen concentration was dynamically controlled according to the calcination process temperature and calcination time to complete the calcination.

[0041] The coal gangue calcination product was rapidly quenched using a phase change medium, and the activity was adjusted after the coal gangue calcination product cooled to obtain the coal gangue product.

[0042] The chemical composition includes carbon content, SiO2 content, Al2O3 content, and Fe2O3 content;

[0043] The calcination experimental data includes thermal analysis experimental data and X-ray diffraction phase analysis data.

[0044] In this embodiment, the method for obtaining coal gangue calcined feed includes:

[0045] The chemical composition of the coal gangue fragments was determined by X-ray diffraction phase analysis. The amount of lignite powder to be added was calculated based on the carbon content of the coal gangue fragments, using the following formula:

[0046] ;

[0047] in This refers to the amount of lignite powder added. For the target carbon content, Carbon content of coal gangue crushed material The bulk density of lignite powder, The moisture content of lignite powder. For the quality of the coal gangue fragments to be processed, This is a correction factor for calorific value fluctuations;

[0048] In the actual assessment, 1000 kg of coal gangue from a certain mining area was used as raw material, and the following pretreatment operations were performed:

[0049] Crushing and screening: The jaw crusher is used for coarse crushing to a particle size of <50mm, then a vertical impact crusher is used for fine crushing, and finally the material is screened through a vibrating screen (screen mesh size 0.175mm) to obtain 850kg of coal gangue crushed material with a particle size of <0.175mm (80 mesh).

[0050] Magnetic separation for iron removal: A permanent magnet drum magnetic separator with a magnetic field strength of 1.2T is used to dry magnetically separate the coal gangue fragments to remove most of the magnetic Fe3O4 and elemental iron. After iron removal, 820kg of clean coal gangue is obtained.

[0051] Chemical composition determination: Random samples of clean coal gangue after iron removal were analyzed by X-ray fluorescence spectroscopy (XRF). The mean value of the analysis results of each sample was taken, and the main chemical components (mass percentage) were determined to be: SiO2 / 52.3%, Al2O3 / 28.7%, Fe2O3 / 3.1%, and the initial carbon content was [not specified]. It is 4.2%;

[0052] Set target carbon content The proportion is 10%, utilizing its own carbonaceous material as part of the heat source, and lignite powder (bulk density) is selected. It is 0.75 g / cm³ 3 Moisture content (12%) is used as a supplementary carbon source, with a calorific value fluctuation correction factor. The value is 1.02. The amount of lignite powder required to produce 1 kg of coal gangue crushed material is calculated to be 0.09 kg. The two are mixed evenly in a twin-shaft mixer to obtain coal gangue calcined material.

[0053] In this embodiment, the method for fitting and obtaining the three-stage calcination temperature model includes:

[0054] Calcination experiments were conducted on different coal gangues to obtain thermal analysis data and X-ray diffraction phase analysis data, and the calcination temperature of different coal gangues was determined. The specific method is as follows:

[0055] The peak temperature of hydroxyl removal from kaolinite was taken as the calcination temperature of the dehydration stage; the temperature at which kaolinite transforms into metakaolinite and carbonate minerals decompose was taken as the calcination temperature of the decomposition and crystal transformation stage; and the temperature at which the glass phase forms the fastest was taken as the calcination temperature of the activation sintering stage.

[0056] The chemical composition of different coal gangues was determined, and a three-stage calcination temperature model was obtained by linear fitting of the calcination process temperatures of different coal gangues. The expression is as follows:

[0057] ;

[0058] in for Calcination temperature at each stage, calcination stage index It includes the dehydration stage, the decomposition and crystal transformation stage, and the activation sintering stage. for Stage reference calcination temperature, The first activation coefficient, The second activation coefficient, The mass of SiO2 in the raw material. The mass of Al2O3 in the raw material. The Fe2O3 content in the raw materials This is a reference value for the mass ratio of SiO2 to Al2O3 in the regional raw materials. This is a reference value for the Fe2O3 content of raw materials in the region;

[0059] In the actual evaluation, 10 types of coal gangue from different origins were collected, and calcination experiments were conducted at various stages using the controlled variable method. The calcination temperatures of different coal gangues were obtained through analysis using a combined thermal analyzer (TG-DSC) and a high-temperature X-ray diffractometer (HT-XRD).

[0060] Dehydration stage: Constant temperature calcination at different temperatures (350-550℃), the temperature point at which the structural water is removed fastest is determined by TG curve, and the calcination temperature of the activation sintering stage of coal gangue from different origins is determined by combining the DSC endothermic peak.

[0061] Decomposition and crystal transformation stage: Calcination at different temperatures (750-950℃) was carried out at constant temperature. The temperature at which the characteristic peak of kaolinite (d≈7.15Å) disappeared and the temperature at which the amorphous diffuse peak of metakaolinite (2θ=20-25°) appeared was monitored by XRD to determine the calcination temperature of coal gangue from different origins during the decomposition and crystal transformation stages.

[0062] Activation sintering stage: Calcination at different temperatures (950-1150℃) isothermal, the amorphous phase content is calculated by XRD full spectrum fitting, the temperature point with the fastest glass phase formation rate is found, and the calcination temperature of the activation sintering stage of coal gangue from different origins is determined.

[0063] The SiO2, Al2O3, and Fe2O3 contents of different coal gangues were determined, and a three-stage calcination temperature model was obtained by linear fitting with the calcination temperature of different coal gangues. The expression is as follows:

[0064] ;

[0065] ;

[0066] ;

[0067] in The calcination temperature during the dehydration stage. The calcination temperature during the decomposition and crystal transformation stages. The calcination temperature during the activation sintering stage, and the second activation coefficient for this stage. The negative value is due to the excessively high Fe2O3 content.

[0068] The chemical composition of the coal gangue calcined material to be calcined was input into the three-stage calcination temperature model, and the calcination process temperatures were obtained as 451.9℃, 851.3℃, and 1049.4℃.

[0069] In this embodiment, the method for dynamically controlling the oxygen concentration based on the calcination process temperature and calcination time includes:

[0070] The chemical composition of the coal gangue calcined material to be calcined is input into the three-stage calcination temperature model to obtain the calcination process temperature;

[0071] Calcination tests were conducted on the coal gangue to be calcined according to the calcination process temperature. The design calcination time for each stage was determined based on the calcination test data. The specific method is as follows:

[0072] The mass loss curve of coal gangue was determined by thermogravimetric analysis (TG) curve. Dehydration was considered complete when the mass loss rate dropped to 5% of the initial rate, and the designed calcination time for the dehydration stage of coal gangue was obtained. When the intensity of the characteristic peak of kaolinite in the XRD pattern dropped to less than 3% of the original intensity, the crystal transformation was considered complete, and the designed calcination time for the decomposition and crystal transformation stage of coal gangue was obtained. When the change rate of the amorphous diffuse peak area in the XRD pattern was less than 0.3% / min, the activation was considered complete, and the designed calcination time for the activation and sintering stage of coal gangue was obtained.

[0073] Calcination is carried out according to the calcination process temperature and the designed calcination time for each stage. The oxygen concentration is adjusted by measuring the actual calcination temperature in the furnace. The specific operation is as follows:

[0074] When the actual calcination temperature in the furnace is less than the first temperature threshold and the calcination time is less than the first time threshold, maintain the standard fan power; when the actual calcination temperature in the furnace is greater than the second temperature threshold and the calcination time is greater than the second time threshold, turn off the fan; otherwise, increase the fan power.

[0075] In practical evaluation, 1–2% Na₂CO₃ by mass was added as an activator to the coal gangue calcining material to be calcined and mixed evenly. Small-scale calcination tests were conducted in a box-type resistance furnace at calcination temperatures (451.9℃, 851.3℃, and 1049.4℃) to determine the optimal time for each stage.

[0076] Dehydration stage time: The mass loss of the material at 451.9℃ is detected by online thermogravimetric analysis. When the mass loss rate drops to 5% of the initial rate, dehydration is considered complete. The recording time is 20 minutes.

[0077] Decomposition and crystal transformation stage time: At 851.3℃, samples were taken every 5 minutes for rapid XRD analysis. When the intensity of the kaolinite characteristic peak dropped to 3% of the original intensity, the transformation was determined to be complete. The recording time was 25 minutes.

[0078] Activation sintering stage time: At 1049.4℃, the change in the area of ​​the amorphous diffuse peak was monitored by XRD. When the change rate was less than 0.3% / min, the activation was considered complete, and the recording time was 15 minutes.

[0079] In an industrial rotary kiln, calcination is carried out according to the temperature and time parameters determined above, and dynamic oxygen concentration control is implemented: the first temperature threshold is set to 600℃, the first time threshold is 1 / 3 of the total calcination time (i.e. (20+25+15) / 3=20 minutes), the second temperature threshold is set to 950℃, and the second time threshold is 2 / 3 of the total calcination time (i.e. 40 minutes).

[0080] In the initial stage, maintain standard blower power and control the combustion blower to operate at a lower power to keep the oxygen concentration in the kiln at 5-8%, achieving slow heating and partial combustion of carbonaceous materials. In the middle stage, increase the blower power to raise the oxygen concentration to 12-18%, ensuring complete combustion and decomposition reactions. In the later stage, turn off the combustion blower and introduce a small amount of N2 to reduce the oxygen concentration to 3-5%, creating a weak reducing atmosphere and inhibiting Fe production. 3+ Massive generation and excessive crystal growth.

[0081] In this embodiment, the phase change medium for rapid quenching is specifically a molten salt bath at 280±20℃; the molten salt bath is composed of a mixture of NaNO3 and KNO3 with a melting point of 220℃.

[0082] In this embodiment, the specific steps of the activity regulation are as follows: the cooled coal gangue calcination product is ultrasonically treated in a weakly alkaline buffer solution for 30 minutes; the pH range of the weakly alkaline buffer solution is 8.5-9.0.

[0083] The calcined coal gangue product after quenching and cooling was ground to a particle size of <0.075mm (200 mesh), and then placed in a Na2CO3-NaHCO3 buffer solution with a pH=8.8 and a solid-liquid ratio of 1:10. The slurry was ultrasonically treated for 30 minutes using an ultrasonic cell disruptor (power density set to 0.5 W / cm²). The Si-O-Al bonds were further opened through the ultrasonic cavitation effect to enhance surface activity. Finally, the coal gangue product was obtained by drying.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for enhancing and activating coal gangue through high-temperature calcination, characterized in that, Includes the following steps: S1. The coal gangue is crushed, screened, and magnetically separated to remove iron to obtain coal gangue crushed material. The chemical composition of the coal gangue crushed material is determined. Lignite powder is added according to the chemical composition of the coal gangue crushed material to obtain coal gangue calcined material. S2. Obtain calcination experimental data of different coal gangues, fit a three-stage calcination temperature model, and input the chemical composition of the coal gangue calcined material to be calcined into the three-stage calcination temperature model to obtain the calcination process temperature. S3. Calcinate the coal gangue calcined material according to the calcination process temperature, determine the designed calcination time for each stage, and calcine the coal gangue calcined material. Dynamically control the oxygen concentration according to the calcination process temperature and calcination time to complete the calcination. S4. The coal gangue calcination product is rapidly quenched using a phase change medium, and the activity is adjusted after the coal gangue calcination product is cooled to obtain the coal gangue product. The chemical composition includes carbon content, SiO2 content, Al2O3 content, and Fe2O3 content; The calcination experimental data includes thermal analysis experimental data and X-ray diffraction phase analysis data; The method for fitting and obtaining the three-stage calcination temperature model includes: Calcination experiments were conducted on different coal gangues to obtain thermal analysis data and X-ray diffraction phase analysis data, and the calcination temperature of different coal gangues was determined. The specific method is as follows: The peak temperature of hydroxyl removal from kaolinite was taken as the calcination temperature of the dehydration stage; the temperature at which kaolinite transforms into metakaolinite and carbonate minerals decompose was taken as the calcination temperature of the decomposition and crystal transformation stage; and the temperature at which the glass phase forms the fastest was taken as the calcination temperature of the activation sintering stage. The chemical composition of different coal gangues was determined, and a three-stage calcination temperature model was obtained by linear fitting of the calcination process temperatures of different coal gangues. The expression is as follows: ； in for Calcination temperature at each stage, calcination stage index It includes the dehydration stage, the decomposition and crystal transformation stage, and the activation sintering stage. for Stage reference calcination temperature, The first activation coefficient, The second activation coefficient, The mass of SiO2 in the raw material. The mass of Al2O3 in the raw material. The Fe2O3 content in the raw materials This is a reference value for the mass ratio of SiO2 to Al2O3 in the regional raw materials. This is a reference value for the Fe2O3 content of the raw materials in the region.

2. The method for enhancing and activating coal gangue through high-temperature calcination according to claim 1, characterized in that, The method for obtaining coal gangue calcined feedstock includes: The chemical composition of the coal gangue fragments was determined by X-ray diffraction phase analysis. The amount of lignite powder to be added was calculated based on the carbon content of the coal gangue fragments, using the following formula: ； in This refers to the amount of lignite powder added. For the target carbon content, Carbon content of coal gangue crushed material The bulk density of lignite powder, The moisture content of lignite powder. For the quality of the coal gangue fragments to be processed, This is the correction factor for calorific value fluctuation.

3. The method for enhancing and activating coal gangue through high-temperature calcination according to claim 1, characterized in that: The method for dynamically controlling oxygen concentration based on calcination temperature and calcination time includes: The chemical composition of the coal gangue calcined material to be calcined is input into the three-stage calcination temperature model to obtain the calcination process temperature; Calcination tests were conducted on the coal gangue to be calcined according to the calcination process temperature. The design calcination time for each stage was determined based on the calcination test data. The specific method is as follows: The mass loss curve of coal gangue was determined by thermogravimetric analysis (TG) curve. Dehydration was considered complete when the mass loss rate dropped to 5% of the initial rate, and the designed calcination time for the dehydration stage of coal gangue was obtained. When the intensity of the characteristic peak of kaolinite in the XRD pattern dropped to less than 3% of the original intensity, the crystal transformation was considered complete, and the designed calcination time for the decomposition and crystal transformation stage of coal gangue was obtained. When the change rate of the amorphous diffuse peak area in the XRD pattern was less than 0.3% / min, the activation was considered complete, and the designed calcination time for the activation and sintering stage of coal gangue was obtained. Calcination is carried out according to the calcination process temperature and the designed calcination time for each stage. The oxygen concentration is adjusted by measuring the actual calcination temperature in the furnace. The specific operation is as follows: When the actual calcination temperature in the furnace is less than the first temperature threshold and the calcination time is less than the first time threshold, maintain the standard fan power; when the actual calcination temperature in the furnace is greater than the second temperature threshold and the calcination time is greater than the second time threshold, turn off the fan; otherwise, increase the fan power.

4. The method for enhancing and activating coal gangue through high-temperature calcination according to claim 1, characterized in that, The phase change medium for rapid quenching is specifically a molten salt bath at 280±20℃; the molten salt bath is composed of a mixture of NaNO3 and KNO3 with a melting point of 220℃.

5. The method for enhancing and activating coal gangue through high-temperature calcination according to claim 1, characterized in that: The specific steps for regulating the activity are as follows: the cooled coal gangue calcination product is ultrasonically treated in a weakly alkaline buffer solution for 30 minutes; the pH range of the weakly alkaline buffer solution is 8.5-9.0.

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