A method for preparing ultrafine modified coal gangue powder

Abstract

The present application belongs to the field of new material preparation technology, and discloses a method for preparing ultrafine modified coal gangue powder. The method described in the present invention can obtain ultrafine powder with uniform particle size distribution and regular morphology, and may introduce new crystal forms or amorphous phases, optimize the microstructure of the powder, and activate the minerals in the gangue, exposing more active sites, thereby improving the reactivity of the final product and facilitating subsequent applications. The ultrafine coal gangue powder obtained by the method described in the present invention has a finer particle size and a larger specific surface area, which not only increases the chance of contact with external substances, but also enhances its reactivity and adsorption capacity in various applications. The particle size distribution of the present invention is very ideal for many applications. For example, it can provide a higher filling density and better mechanical properties when used as a filling material.

Description

Technical Field

[0001] The present application relates to the field of new material manufacturing technology, and specifically to a method for preparing ultrafine modified coal gangue powder. Background Art

[0002] Gangue is a solid waste generated during coal mining and washing, typically containing a certain amount of carbonaceous material and other minerals. It is estimated that China produces approximately 600 million tons of gangue annually, accounting for more than one-third of the country's total industrial solid waste. For a long time, this gangue has been simply piled or landfilled, which not only consumes a large amount of land resources but also may trigger geological disasters such as landslides and mudslides. Over time, harmful components in the gangue gradually seep into the soil and groundwater, causing environmental pollution.

[0003] From another perspective, coal gangue is also an underutilized mineral resource. Research shows that, in addition to containing a small amount of carbon, coal gangue is also rich in various elements such as silicon (Si), aluminum (Al), iron (Fe), and calcium (Ca). The calcium content, in particular, can be used to make various building materials such as cement and bricks and tiles.

[0004] However, the uneven hardness and brittleness of coal gangue, along with its large and irregularly shaped particles, make it difficult to achieve the required performance in certain applications. In particular, the severe agglomeration of raw coal gangue particles makes it difficult to mix evenly with other materials, reducing its suitability for composite materials or other applications. Furthermore, the relatively inert surface of coal gangue and its low chemical reactivity limit its use in applications requiring high reactivity. Summary of the Invention

[0005] Purpose of the Invention: To address the shortcomings of existing technologies, the present invention proposes a method for preparing ultrafine modified gangue powder. The resulting ultrafine gangue powder possesses a suitable particle size and a large specific surface area. This method addresses many of the issues associated with direct use of gangue and provides a new, higher-value-added application path, transforming it from a waste product into a valuable resource.

[0006] Technical solution: The present invention provides a method for preparing ultrafine modified coal gangue powder, the specific steps are as follows:

[0007] First, prepare an isopropyl alcohol aqueous solution at a ratio of 10g isopropyl alcohol to 500ml water. This isopropyl alcohol lowers the freezing point. When heated gangue is quickly poured into the solution, the extreme temperature difference causes the gangue surface to shrink rapidly, generating internal stress that causes the gangue to break into smaller particles. This step helps increase the specific surface area of ​​the gangue, providing more active sites for subsequent chemical reactions.

[0008] Large lumps of gangue are initially crushed to meet the requirements of subsequent processing equipment. The crushed gangue is rapidly heated to 800±20°C. This process must be completed quickly. The rapid heating creates a temperature difference between the inside and outside of the mineral particles, leading to lattice distortion and stress differences, forming microcracks. This, in particular for mineral components such as quartz, helps reduce their binding energy and facilitates subsequent crushing. For the present invention, the heating rate is greater than 200°C / min, preferably 250°C / min. The heated gangue is immediately poured into the aforementioned isopropyl alcohol aqueous solution for quenching. The significant temperature difference causes the mineral particles to burst instantly. The bursting gangue is then divided into two equal portions, one for future use and the other for acid hydrolysis and alkali neutralization to produce a precipitate. This precipitate is mixed with the remaining equal mass of the reserved gangue and then loaded into a ball mill for grinding. The acid hydrolysis (acid leaching) treatment of the gangue dissolves some unstable mineral phases and releases soluble metal ions. These ions form hydroxide precipitates after the addition of NaOH. This chemical treatment can change the composition of the gangue, exposing more active sites, thereby improving the reaction activity in subsequent processing or applications. At the same time, mixing two gangues in different treatment states can help produce a more uniform and finer particle distribution during the ball milling process because the hardness and brittleness of the two may be different. Moreover, the part treated with acid hydrolysis and alkali neutralization may introduce new crystalline or amorphous phases. When mixed with the original gangue, it can promote the formation of new phases during the grinding process and further optimize the microstructure of the powder.

[0009] After grinding, the ground slurry is subjected to solid-liquid separation for 10-20 minutes. After separation, the solid precipitate is dried and then ground and dispersed to obtain a powder with a particle size D50 of less than 2 μm. The powder is evenly spread on the rotating disk of a corona treater, with the rotation speed set to 5-15 rpm, the corona discharge voltage set to 20 kV, the current density set to approximately 0.1 mA / cm², and the nitrogen flow rate set to 1 L / min. The corona discharge device is turned on. During this process, high-energy electrons will impact the surface of the coal gangue particles, causing surface molecular bonds to break, forming free radicals and other active sites, and changing the surface properties of the powder. The treatment lasts for 3-5 minutes. After completion, the coal gangue powder is obtained.

[0010] Specifically, the grinding is performed using zirconia ceramic balls with a diameter of 2 mm as grinding media at a rotation speed of 1500 rpm for 60-90 minutes.

[0011] Specifically, the drying is carried out at 95° C. under vacuum conditions.

[0012] Specifically, the rotation speed is preferably set to 10 rpm.

[0013] Specifically, the acid hydrolysis is as follows: adding 6M HCl solution at a solid-liquid ratio of 1:10, stirring at 80° C. for 30 minutes, filtering after the reaction is completed, and collecting the filtrate.

[0014] Specifically, the alkali neutralization is as follows: slowly adding 5% NaOH solution to the filtrate until the pH value reaches 9-10 to obtain a precipitate.

[0015] As a further improvement, the coal gangue after explosion was loaded into a ball mill, a modifier (a n-propanol solution containing 2 wt% KH550) was added, and zirconia ceramic balls (2 mm in diameter) were used as grinding media. The mill was ground at a speed of 800 rpm for 100-120 minutes.

[0016] A further improvement is that while the corona discharge is being treated, a modifier is slowly sprayed into the treatment area through a precision sprayer. The modifier is a n-propanol solution containing 2wt% KH550, and the total liquid volume is 10ml to ensure that the modifier is evenly covered on the surface of the gangue powder. Adding the modifier during the corona treatment process can improve the compatibility between the gangue powder and the polymer matrix, prevent the delamination or peeling phenomenon caused by temperature changes, and increase the thermal stability of the material. At the same time, through the effect of the modifier, the bonding between the gangue powder and the polymer matrix is ​​strengthened, thereby improving the strength, toughness and impact resistance of the hollow board.

[0017] Beneficial effects: The present invention reduces the occurrence of agglomeration during the preparation process by mixing raw materials in different processing states. To a certain extent, the particle size and morphology of the final powder can be regulated to obtain an ultrafine powder with uniform particle size distribution and regular morphology. At the same time, new crystal forms or amorphous phases may be introduced, thereby optimizing the microstructure of the powder and activating the minerals in the gangue, exposing more active sites, thereby improving the reaction activity of the final product and facilitating subsequent applications.

[0018] The ultrafine gangue powder produced by the method of the present invention has a finer particle size and a larger specific surface area, which not only increases its contact with external substances but also enhances its reactivity and adsorption capacity in various applications. The particle size distribution of the present invention is highly ideal for many applications, such as providing higher packing density and better mechanical properties when used as a filler.

[0019] The preparation method provided by the present invention fully utilizes the industrial waste material of coal gangue and converts it into high value-added ultrafine powder material, thereby realizing the recycling of waste and helping to reduce the environmental burden. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1The sample prepared in Example 1 is shown.

[0021] Figure 2 This is the SEM electron microscope image of the sample prepared in Example 1.

[0022] Figure 3 This is the SEM electron microscope image of the coal gangue raw material processed in Example 1. DETAILED DESCRIPTION

[0023] The technical solution of the present application is described in detail below through examples, but the protection scope of the present application is not limited to the examples. Example

[0024] Prepare an isopropanol aqueous solution (ratio: 10g isopropanol: 500ml water) for later use. Preliminarily crush the bulk gangue, then rapidly heat the crushed gangue to approximately 800°C at a heating rate of 250°C / min. Immediately pour the heated gangue into the above solution for quenching, resulting in cracked gangue. Divide the mixture into two equal portions, one for later use, and the other portion into a 6M HCl solution at a solid-to-liquid ratio of 1:10. Stir at 80°C for 30 minutes. After the reaction is complete, filter the mixture, and slowly add 5% NaOH solution to the filtrate until the pH reaches 9-10 to obtain a precipitate. This precipitate is mixed with an equal amount of the above-mentioned gangue and loaded into a ball mill. Mill the mixture at 1500 rpm for 60-90 minutes using zirconia ceramic balls (2mm diameter) as grinding media.

[0025] After grinding, the ground slurry is separated into solid and liquid using a centrifuge for about 10 to 20 minutes. The separated liquid can be returned to the production process for recycling. The solid precipitate is dried under low temperature (95°C) vacuum conditions and then ground and dispersed to obtain a powder with a particle size D50 less than 2μm.

[0026] The above powder was evenly spread on the rotating disk of the corona treater, the rotation speed was set to 10rpm, the corona discharge voltage was set to 20kV, the current density was about 0.1mA / cm², the nitrogen flow rate was 1L / min, the corona discharge device was turned on, and the treatment time was 3 minutes. After the treatment was completed, the coal gangue powder was obtained. Figure 1 The SEM electron microscope image of the obtained coal gangue powder is shown as follows: Figure 2 As shown. The SEM electron microscope image of the gangue raw material is as follows Figure 3 As shown. Figure 2 and Figure 3 From the comparison, it can be seen that the surface microstructure of the coal gangue raw material before treatment and the ultrafine coal gangue powder after treatment are obviously different. Example

[0027] Prepare an isopropanol aqueous solution (ratio: 10g isopropanol: 500ml water) for later use. Preliminarily crush the bulk gangue and rapidly heat the crushed gangue to approximately 800°C at a heating rate of 50°C / min. Immediately pour the heated gangue into the above solution for quenching, resulting in cracked gangue. Divide the mixture into two equal portions, one for later use, and the other portion into a 6M HCl solution at a solid-to-liquid ratio of 1:10. Stir at 80°C for 30 minutes. After the reaction is complete, filter the mixture, and slowly add 5% NaOH solution to the filtrate until the pH reaches 9-10 to obtain a precipitate. This precipitate is mixed with an equal amount of the above-mentioned gangue and loaded into a ball mill. Mill the mixture at 1500 rpm for 60-90 minutes using zirconia ceramic balls (2mm diameter) as the grinding medium.

[0028] After grinding, the ground slurry is separated into solid and liquid using a centrifuge for about 10 to 20 minutes. The separated liquid can be returned to the production process for recycling. The solid precipitate is dried under low temperature (95°C) vacuum conditions and then ground and dispersed to obtain a powder with a particle size D50 less than 2μm.

[0029] The above powder was evenly spread on the rotating disk of the corona treater, the rotation speed was set to 10 rpm, the corona discharge voltage was set to 20 kV, the current density was about 0.1 mA / cm², the nitrogen flow rate was 1 L / min, the corona discharge device was turned on, and the treatment time was 3 minutes. After the treatment was completed, coal gangue powder was obtained. Example

[0030] The large pieces of coal gangue were preliminarily crushed, and the crushed coal gangue was rapidly heated to about 800°C at a heating rate of 250°C / min. The heated coal gangue was immediately poured into water for quenching to obtain the exploded coal gangue, which was divided into two equal parts, one of which was reserved, and the other part was added with 6M HCl solution at a solid-liquid ratio of 1:10. The mixture was stirred at 80°C for 30 minutes. After the reaction was completed, it was filtered, and 5% NaOH solution was slowly added to the filtrate until the pH value reached 9~10 to obtain a precipitate. The precipitate was mixed with the above-mentioned reserved coal gangue of equal mass, and the two were loaded into a ball mill. Zirconia ceramic balls (diameter 2mm) were used as grinding media and ground at a speed of 1500rpm for 60-90 minutes.

[0031] After grinding, the ground slurry is separated into solid and liquid using a centrifuge for about 10 to 20 minutes. The separated liquid can be returned to the production process for recycling. The solid precipitate is dried under low temperature (95°C) vacuum conditions and then ground and dispersed to obtain a powder with a particle size D50 less than 2μm.

[0032] The above powder was evenly spread on the rotating disk of the corona treater, the rotation speed was set to 10 rpm, the corona discharge voltage was set to 20 kV, the current density was about 0.1 mA / cm², the nitrogen flow rate was 1 L / min, the corona discharge device was turned on, and the treatment time was 3 minutes. After the treatment was completed, coal gangue powder was obtained.

[0033] Comparative Example 1

[0034] Prepare an isopropyl alcohol-water solution (ratio: 10g isopropyl alcohol: 500ml water) and set aside. Initially crush the large gangue. Rapidly heat the crushed gangue to approximately 800°C at a rate of 50°C / min. Immediately pour the heated gangue into the solution for quenching. Place the cracked gangue into a ball mill and grind at 1500 rpm for 60-90 minutes using zirconia ceramic balls (2mm diameter) as the grinding medium.

[0035] After grinding, the ground slurry is separated into solid and liquid using a centrifuge for about 10 to 20 minutes. The separated liquid can be returned to the production process for recycling. The solid precipitate is dried under low temperature (95°C) vacuum conditions and then ground and dispersed to obtain a powder with a particle size D50 less than 2μm.

[0036] The above powder was evenly spread on the rotating disk of the corona treater, the rotation speed was set to 10 rpm, the corona discharge voltage was set to 20 kV, the current density was about 0.1 mA / cm², the nitrogen flow rate was 1 L / min, the corona discharge device was turned on, and the treatment time was 3 minutes. After the treatment was completed, coal gangue powder was obtained.

[0037] Comparative Example 2

[0038] The large pieces of coal gangue were preliminarily crushed and divided into two equal parts. One part was reserved and the other part was added with 6M HCl solution at a solid-liquid ratio of 1:10. The mixture was stirred at 80°C for 30 minutes. After the reaction was completed, the mixture was filtered and 5% NaOH solution was slowly added to the filtrate until the pH value reached 9-10 to obtain a precipitate. The precipitate was mixed with the above-mentioned reserved coal gangue of equal mass and loaded into a ball mill. Zirconia ceramic balls (2 mm in diameter) were used as grinding media and ground at 1500 rpm for 60-90 minutes.

[0039] After grinding, the ground slurry is separated into solid and liquid using a centrifuge for about 10 to 20 minutes. The separated liquid can be returned to the production process for recycling. The solid precipitate is dried under low temperature (95°C) vacuum conditions and then ground and dispersed to obtain a powder with a particle size D50 less than 2μm.

[0040] The above powder was evenly spread on the rotating disk of the corona treater, the rotation speed was set to 10 rpm, the corona discharge voltage was set to 20 kV, the current density was about 0.1 mA / cm², the nitrogen flow rate was 1 L / min, the corona discharge device was turned on, and the treatment time was 3 minutes. After the treatment was completed, coal gangue powder was obtained.

[0041] Comparative Example 3

[0042] Prepare an isopropanol aqueous solution (ratio: 10g isopropanol: 500ml water) for later use. Preliminarily crush the bulk gangue, then rapidly heat the crushed gangue to approximately 800°C at a heating rate of 250°C / min. Immediately pour the heated gangue into the above solution for quenching, resulting in cracked gangue. Divide the mixture into two equal portions, one for later use, and the other portion into a 6M HCl solution at a solid-to-liquid ratio of 1:10. Stir at 80°C for 30 minutes. After the reaction is complete, filter the mixture, and slowly add 5% NaOH solution to the filtrate until the pH reaches 9-10 to obtain a precipitate. This precipitate is mixed with an equal amount of the above-mentioned gangue and loaded into a ball mill. Mill the mixture at 1500 rpm for 60-90 minutes using zirconia ceramic balls (2mm diameter) as grinding media.

[0043] Use a centrifuge to separate the solid and liquid of the ground slurry for about 10 to 20 minutes. The separated liquid can be returned to the production process for recycling. The solid precipitate is dried under low temperature (95°C) vacuum conditions and then ground and dispersed to obtain coal gangue powder.

[0044] The test data of the coal gangue powder prepared in Examples 1 to 3 and Comparative Examples 1 to 3 are as follows:

[0045]

[0046] Comparative Example 1 did not divide the coal gangue into two halves before processing and then mixing; Comparative Example 2 did not use the rapid heating and cooling treatment method; and Comparative Example 3 did not use corona treatment in the subsequent stage. A comparison of the above data shows that the coal gangue powder obtained by the treatment method used in Example 1 has a finer particle size, a larger specific surface area, and a higher porosity, with a suitable particle size and an ideal pore structure.

[0047] Application Test 1

[0048] The gangue powder obtained in Example 1 was used to produce stone paper. The resulting stone paper had a stiffness of 0.5 mN·m, a tensile strength of 51 MPa, and a tear strength of 150 mN·m² / g.

[0049] The gangue powder obtained in Example 1 was used to manufacture a hollow board. The hollow board had a tensile strength of 25.1 MPa, a flexural strength of 34.1 MPa, a heat deformation temperature of 112°C, and a Vicat softening point of 145°C.

[0050] Application Test 2

[0051] The gangue powder obtained in Comparative Example 1 was used to produce stone paper. The resulting stone paper had a stiffness of 0.5 mN·m, a tensile strength of 43 MPa, and a tear strength of 125 mN·m² / g.

[0052] The gangue powder obtained in Comparative Example 1 was used to manufacture a hollow board. The hollow board had a tensile strength of 20.8 MPa, a flexural strength of 30.5 MPa, a heat deformation temperature of 112°C, and a Vicat softening point of 145°C.

[0053] Application Test 3

[0054] The gangue powder obtained in Comparative Example 2 was used to produce stone paper. The resulting stone paper had a stiffness of 0.5 mN·m, a tensile strength of 48 MPa, and a tear strength of 134 mN·m² / g.

[0055] The gangue powder obtained in Comparative Example 2 was used to manufacture a hollow board. The hollow board had a tensile strength of 21.2 MPa, a flexural strength of 29.8 MPa, a heat deformation temperature of 112°C, and a Vicat softening point of 145°C.

[0056] Application Test 4

[0057] The gangue powder obtained in Comparative Example 3 was used to produce stone paper. The resulting stone paper had a stiffness of 0.5 mN·m, a tensile strength of 44 MPa, and a tear strength of 132 mN·m² / g.

[0058] The gangue powder obtained in Comparative Example 3 was used to manufacture a hollow board. The resulting hollow board had a tensile strength of 18.9 MPa, a flexural strength of 21.9 MPa, a heat deformation temperature of 110°C, and a Vicat softening point of 142°C.

[0059] The above experiments show that the stone paper and hollow board prepared using the gangue powder obtained in Example 1 as raw material are superior to those prepared using the gangue powder obtained in Comparative Examples 1 to 3. The performance of the product obtained in Comparative Example 3 is significantly lower, indicating that corona treatment has a significant impact on the performance of subsequent products. Example 4

[0060] Prepare an isopropanol aqueous solution (ratio: 10g isopropanol: 500ml water) and set aside. Initially crush the bulk gangue. Rapidly heat the crushed gangue to approximately 800°C at a rate of 250°C / min. Immediately pour the heated gangue into the solution for quenching. Place the cracked gangue into a ball mill, add a modifier (n-propanol solution containing 2wt% KH550), and grind at 800 rpm for 100-120 minutes using zirconia ceramic balls (2mm diameter) as the grinding medium to achieve organic modification of the mineral particle surface, improving its dispersibility and compatibility with other materials.

[0061] After grinding, the ground slurry is separated into solid and liquid using a centrifuge for about 10 to 20 minutes. The separated liquid can be returned to the production process for recycling. The solid precipitate is dried under low temperature (95°C) vacuum conditions and then ground and dispersed to obtain a powder with a particle size D50 less than 2μm.

[0062] The powder was evenly spread on the rotating disk of a corona treater. The rotation speed was set to 10 rpm, the corona discharge voltage was set to 20 kV, the current density was approximately 0.1 mA / cm², the nitrogen flow rate was set to 1 L / min, the corona discharge device was turned on, and the treatment time was 3 minutes. After treatment, the coal gangue powder of the present invention was obtained. Example 5

[0063] Prepare an isopropyl alcohol-water solution (ratio: 10g isopropyl alcohol: 500ml water) and set aside. Initially crush the large gangue. Rapidly heat the crushed gangue to approximately 800°C at a rate of 250°C / min. Immediately pour the heated gangue into the solution for quenching. Load the cracked gangue into a ball mill and grind at 1500 rpm for 60-90 minutes using zirconia ceramic balls (2mm diameter) as the grinding medium.

[0064] After grinding, the ground slurry is separated into solid and liquid using a centrifuge for about 10 to 20 minutes. The separated liquid can be returned to the production process for recycling. The solid precipitate is dried under low temperature (95°C) vacuum conditions and then ground and dispersed to obtain a powder with a particle size D50 less than 2μm.

[0065] The above powder is evenly spread on the rotating disk of the corona treater, the rotation speed is set to 10rpm, the corona discharge voltage is set to 20kV, the current density is about 0.1mA / cm², the nitrogen flow rate is 1L / min, the corona discharge device is turned on, and the treatment time is 3 minutes. While the corona discharge treatment is in progress, a modifier (a n-propanol solution containing 2wt% KH550) is slowly sprayed into the treatment area through a precision sprayer, with a total liquid volume of 10ml, to ensure that the modifier is evenly covered on the surface of the coal gangue powder. Since the modifier used in this case is an organic solvent-soluble type, no additional cleaning step is required. After the treatment is completed, the coal gangue powder of the present invention is obtained.

[0066] Application Test 5

[0067] The gangue powder obtained in Example 4 was used to produce stone paper. The resulting stone paper had a stiffness of 0.5 mN·m, a tensile strength of 50 MPa, and a tear strength of 151 mN·m² / g.

[0068] The gangue powder obtained in Example 4 was used to produce a hollow board. The resulting hollow board had a tensile strength of 35.1 MPa, a flexural strength of 35.1 MPa, a heat deformation temperature of 130°C, and a Vicat softening point of 160°C.

[0069] Application Test 6

[0070] The gangue powder obtained in Example 5 was used to produce stone paper. The resulting stone paper had a stiffness of 0.5 mN·m, a tensile strength of 49 MPa, and a tear strength of 148 mN·m² / g.

[0071] The gangue powder obtained in Example 5 was used to produce a hollow board. The hollow board had a tensile strength of 39.6 MPa, a flexural strength of 35.9 MPa, a heat deformation temperature of 135°C, and a Vicat softening point of 164°C.

[0072] Application Tests 5 and 6 show that adding additives to the gangue powder process has little effect on the production of stone paper and does not improve product performance. However, for hollow board, it can effectively improve its thermal stability, especially during the corona treatment process, which not only improves its mechanical properties but also significantly enhances the product's thermal stability.

Claims

1. A method for preparing ultrafine modified coal gangue powder, characterized in that: Prepare isopropyl alcohol aqueous solution for standby use; preliminarily crush the large pieces of coal gangue, rapidly heat the crushed coal gangue to 800±20℃, with a heating rate greater than 200℃ / min, immediately pour the heated coal gangue into the above isopropyl alcohol aqueous solution for quenching, and obtain the exploded coal gangue, which is divided into two equal parts, one for standby use, and the other for acid hydrolysis, filtering, taking the filtrate, and neutralizing it with alkali to obtain a precipitate, mixing the precipitate with the above-mentioned standby coal gangue of equal mass, and loading them into a ball mill for grinding. After the grinding is completed, , the ground slurry is subjected to solid-liquid separation for 10 to 20 minutes, and after separation, the solid precipitate is dried, and then ground and dispersed to obtain a powder with a particle size D50 less than 2 μm; the above powder is evenly spread on the rotating disk of the corona treater, the rotation speed is set to 5-15 rpm, the corona discharge voltage is set to 20 kV, the current density is 0.1 mA / cm², the nitrogen flow rate is 1 L / min, the corona discharge device is turned on, and the treatment time is 3 to 5 minutes. After the treatment is completed, the coal gangue powder is obtained.

2. The method for preparing ultrafine modified coal gangue powder according to claim 1, characterized in that: The isopropyl alcohol solution is prepared by dissolving 10 g of isopropyl alcohol in 500 ml of water.

3. The method for preparing ultrafine modified coal gangue powder according to claim 1, characterized in that: The heating rate is 250°C / min.

4. The method for preparing ultrafine modified coal gangue powder according to claim 1, characterized in that: The grinding in the ball mill is performed using zirconia ceramic balls with a diameter of 2 mm as grinding media and grinding at a rotation speed of 1500 rpm for 60-90 minutes.

5. The method for preparing ultrafine modified coal gangue powder according to claim 1, characterized in that: The drying is carried out at 95° C. under vacuum conditions.

6. The method for preparing ultrafine modified coal gangue powder according to claim 1, characterized in that: The acid hydrolysis is specifically as follows: adding 6M HCl solution at a solid-liquid ratio of 1:10, stirring at 80° C. for 30 minutes, filtering after the reaction is completed, and collecting the filtrate.

7. The method for preparing ultrafine modified coal gangue powder according to claim 1, characterized in that: The alkali neutralization is as follows: slowly adding 5% NaOH solution to the filtrate until the pH value reaches 9-10 to obtain a precipitate.

8. The method for preparing ultrafine modified coal gangue powder according to claim 1, characterized in that: The rotation speed is set to 10 rpm.

9. The method for preparing ultrafine modified coal gangue powder according to claim 1, characterized in that: A modifier was added during the grinding process in the ball mill. The modifier was a n-propanol solution containing 2 wt % KH550.

10. The method for preparing ultrafine modified coal gangue powder according to claim 1, characterized in that: During the corona discharge treatment, a modifier is slowly sprayed into the treatment area through a precision sprayer. The modifier is a n-propanol solution containing 2 wt % KH550.

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