Coal mine powder residue grouting material, preparation method and application thereof
By preparing coal mine tailings grouting materials and using activated coal mine tailings and other raw materials for particle size distribution and chemical modification, the environmental pollution and land occupation problems of coal-based tailings have been solved, and resource utilization and mine stability have been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HULUNBUIR UNIV
- Filing Date
- 2026-02-02
- Publication Date
- 2026-05-12
AI Technical Summary
The open-air dumping of coal-based tailings leads to environmental pollution and land occupation. Existing technologies are insufficient for effective treatment and utilization, resulting in serious soil and water pollution.
By preparing coal mine slag grouting materials, activated coal mine slag, aluminum ash aqueous solution, aggregates, plant fibers and silica sand are used as raw materials. The materials are then subjected to particle size distribution and chemical modification to form a grouting material with high strength and good fluidity for use in mine filling.
It has enabled the resource utilization of coal-based tailings, solved environmental pollution problems, enhanced the stability and safety of mines, and provided high-strength filling materials.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of solid waste treatment technology, and in particular to a coal mine slag grouting material, its preparation method, and its application. Background Technology
[0002] Coal is a vital resource for modern society, with demand increasing year by year, supporting the operation of basic industries such as power, steel, and chemicals. However, the extraction of this key resource has given rise to serious environmental problems – the disposal of coal-based tailings has become a critical bottleneck for the sustainable development of the mining industry.
[0003] Coal-based tailings are an inevitable byproduct of coal washing and mining. Because of their extremely low coal content, these tailings are unusable and are directly piled up around coal mines. Their complex composition and significant environmental risks are a major concern. Open-air stockpiling not only occupies large amounts of land, but also, due to environmental factors such as microbial degradation, temperature changes, and erosion from acidic or alkaline rainwater, these tailings gradually decompose into coal mine slag. This slag then causes secondary pollution under the influence of wind and water. During the rainy season, leaching forms acidic leachate, leading to severely excessive arsenic levels in the surrounding soil and a surge in cadmium concentrations in groundwater, creating a pollution halo with a radius of several kilometers. Pollutants are also blown into dust by the wind, reducing air quality; and by water, they enter rivers and lakes through runoff, forming a three-dimensional pollution network of "soil-water-food chain." Therefore, how to treat these coal mine slags has become an urgent problem to solve. Summary of the Invention
[0004] The purpose of this invention is to treat and utilize coal mine slag to overcome the problems in the prior art, and to provide a coal mine slag grouting material, its preparation method and application.
[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0006] This invention provides a coal mine slag grouting material, prepared from raw materials comprising the following parts by weight:
[0007] 70-80 parts activated coal mine slag, 30-40 parts aluminum ash aqueous solution, 17-25 parts aggregate, 8-12 parts plant fiber, 7-10 parts silica sand, 2-2.5 parts water-reducing agent, and 10-15 parts mixing water.
[0008] Preferably, the method for preparing activated coal mine slag includes the following steps:
[0009] Activated coal mine slag is obtained by thermally activating coal mine slag.
[0010] The coal mine slag contains components with a particle size of less than or equal to 0.075 mm, components with a particle size greater than 0.075 mm and less than or equal to 0.425 mm, components with a particle size greater than 0.425 mm and less than or equal to 1.18 mm, and components with a particle size greater than 1.18 mm and less than or equal to 2.75 mm.
[0011] The mass ratio of the components with a particle size less than or equal to 0.075 mm, the components with a particle size greater than 0.075 mm and less than or equal to 0.425 mm, the components with a particle size greater than 0.425 mm and less than or equal to 1.18 mm, and the components with a particle size greater than 1.18 mm and less than or equal to 2.75 mm is 20~30:10~15:25~30:30~35.
[0012] The thermal activation temperature is 600~700℃, and the time is 1.5~2.5h.
[0013] Preferably, the method for preparing the aluminum ash aqueous solution includes the following steps:
[0014] Aluminum ash and water are mixed to obtain an aluminum ash aqueous solution;
[0015] The aluminum ash has a particle size ≤0.2mm; the mass ratio of aluminum ash to water is 1:8~12;
[0016] The mixing temperature is 60~80℃, the time is 3~5h, and the rotation speed is 200~300rpm.
[0017] Preferably, the aggregate is crushed granite;
[0018] The aggregate contains components with a particle size of 3~3.75mm and components with a particle size of 3.8~4.25mm;
[0019] The mass ratio of the component with a particle size of 3~3.75mm to the component with a particle size of 3.8~4.25mm is 1:1~1.5.
[0020] Preferably, the method for preparing the plant fiber includes the following steps:
[0021] The plant fiber is obtained by sequentially subjecting Stipa grandis to alkali treatment and coupling treatment.
[0022] The length of the large needlegrass is 2~3.5mm;
[0023] The reagent for alkali treatment is sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 2~2.5%; the temperature of alkali treatment is 60~70℃, and the time is 50~60min;
[0024] The reagent for the coupling treatment is a coupling agent solution, the concentration of the coupling agent solution is 0.5~1%, and the coupling treatment time is 15~30 min;
[0025] The specific surface area of the silica sand is ≥1300 cm². 2 / g;
[0026] The water-reducing agent is a polycarboxylate water-reducing agent and / or a naphthalene-based water-reducing agent.
[0027] The present invention also provides a method for preparing the coal mine slag grouting material, comprising the following steps:
[0028] (1) Mix activated coal slag, aggregate, plant fiber and silica sand to obtain dry material;
[0029] (2) Mix the aluminum ash aqueous solution and the mixing water to obtain a wet material;
[0030] (3) Mix the dry material, wet material and water-reducing agent to obtain the coal mine slag grouting material.
[0031] Preferably, the mixing speed in step (1) is 200~300 rpm and the time is 5~10 min.
[0032] Preferably, the mixing time in step (2) is 60~90s.
[0033] Preferably, the mixing speed in step (3) is 400~500 rpm and the time is 2~3 min.
[0034] The present invention also provides the application of the coal mine slag grouting material in mine backfilling.
[0035] This invention provides a coal mine slag grouting material, prepared from raw materials comprising the following parts by weight: 70-80 parts activated coal mine slag, 30-40 parts aluminum ash aqueous solution, 17-25 parts aggregate, 8-12 parts plant fiber, 7-10 parts silica sand, 2-2.5 parts water-reducing agent, and 10-15 parts mixing water. The main inventive points of this invention are as follows:
[0036] This invention thermally activates coal mine slag, transforming inert kaolinite minerals in the slag into amorphous, highly reactive silicon oxides and aluminum oxides under high temperature. Simultaneously, aluminum ash and water undergo a hydrolysis reaction, where aluminum nitride in the aluminum ash reacts with water to produce aluminum hydroxide and ammonia. The ammonia dissolves in water to form an alkaline slurry, thus providing a strongly alkaline environment for subsequent reactions. In a strong alkaline environment, silicon oxides and aluminum oxides rapidly dissolve upon attack by hydroxide ions, yielding silicate monomers, aluminate monomers, and oligomers with initial monomer linkages. Simultaneously, the alkaline slurry contains a large amount of aluminum ions, causing a rapid increase in the concentration of the aforementioned monomers and oligomers. Dehydration and linkage occur between the monomers and oligomers, forming small units containing Si-O-Si and Si-O-Al bonds through shared oxygen atoms. These small units interconnect to form an aluminosilicate oligomer network, resulting in a gel-like substance. At this point, unreacted active sites within the three-dimensional network gel structure continue to undergo condensation reactions, further increasing the degree of polymerization through alkaline silicon oxide intercalation. This leads to a denser network structure and continuously increasing strength, resulting in a robust filler that serves as a base for grouting.
[0037] Meanwhile, to improve the fluidity and mechanical properties of the grout, this invention performs particle size distribution on coal mine slag and aggregates, allowing for better filling of various spaces; and achieves interlocking between internal components through close packing, thereby improving the material's strength. This invention further utilizes local biomass waste, using *Stipa grandis* as the initial raw material, and performs cellulose removal under alkaline conditions to obtain an intermediate, exposing hydroxyl groups on the surface; further treatment with a silane coupling agent enables efficient connection of the various components in the grouting material, effectively dispersing external forces and achieving improved and long-lasting mechanical properties of the grouting material.
[0038] This invention uses solid waste such as coal mine slag, aluminum ash, and needlegrass as a basis to achieve the goal of treating waste with waste and using waste for reuse. By backfilling these materials into the mine pit, it not only effectively solves the problems of slag accumulation and pollution, but also avoids the risk of mine collapse caused by mining. It achieves multiple benefits. The solution provided by this invention has low process requirements and is suitable for use in mines. Detailed Implementation
[0039] This invention provides a coal mine slag grouting material, prepared from raw materials comprising the following parts by weight:
[0040] 70-80 parts activated coal mine slag, 30-40 parts aluminum ash aqueous solution, 17-25 parts aggregate, 8-12 parts plant fiber, 7-10 parts silica sand, 2-2.5 parts water-reducing agent, and 10-15 parts mixing water.
[0041] In this invention, the preferred mass fraction of activated coal slag is 71-79 parts, more preferably 72-78 parts, and even more preferably 74-76 parts.
[0042] In this invention, the mass fraction of the aluminum ash aqueous solution is preferably 31 to 39 parts, more preferably 32 to 38 parts, and even more preferably 34 to 36 parts.
[0043] In this invention, the mass fraction of aggregate is preferably 18 to 24 parts, more preferably 19 to 23 parts, and even more preferably 20 to 22 parts.
[0044] In this invention, the mass fraction of plant fiber is preferably 8.5 to 11.5 parts, more preferably 9 to 11 parts, and even more preferably 9.5 to 10.5 parts.
[0045] In this invention, the mass fraction of silica sand is preferably 7.5 to 9.5 parts, more preferably 8 to 9 parts, and even more preferably 8.4 to 8.6 parts.
[0046] In this invention, the water-reducing agent is preferably 2.1 to 2.4 parts by mass, more preferably 2.2 to 2.3 parts by mass, and even more preferably 2.25 parts by mass.
[0047] In this invention, the mass fraction of the mixing water is preferably 10.5 to 14.5 parts, more preferably 11 to 14 parts, and even more preferably 12 to 13 parts.
[0048] In this invention, the method for preparing activated coal mine slag includes the following steps:
[0049] Activated coal slag is obtained by thermally activating coal slag.
[0050] In this invention, the coal mine slag contains components with a particle size of less than or equal to 0.075 mm, components with a particle size greater than 0.075 mm and less than or equal to 0.425 mm, components with a particle size greater than 0.425 mm and less than or equal to 1.18 mm, and components with a particle size greater than 1.18 mm and less than or equal to 2.75 mm.
[0051] In this invention, the mass ratio of the component with a particle size less than or equal to 0.075 mm, the component with a particle size greater than 0.075 mm and less than or equal to 0.425 mm, the component with a particle size greater than 0.425 mm and less than or equal to 1.18 mm, and the component with a particle size greater than 1.18 mm and less than or equal to 2.75 mm is preferably 20~30:10~15:25~30:30~35, more preferably 22~28:11~14:26~29:31~34, and even more preferably 24~26:12~13:27~28:32~33.
[0052] In this invention, the temperature for thermal activation is preferably 600~700℃, more preferably 620~680℃, and even more preferably 640~660℃; the time is preferably 1.5~2.5h, more preferably 1.6~2.4h, and even more preferably 1.8~2.2h.
[0053] In this invention, the method for preparing the aluminum ash aqueous solution includes the following steps:
[0054] Aluminum ash is mixed with water to obtain an aluminum ash aqueous solution.
[0055] In this invention, the particle size of the aluminum ash is preferably ≤0.2mm, more preferably ≤0.15mm, and even more preferably ≤0.1mm; the mass ratio of aluminum ash to water is preferably 1:8~12, more preferably 1:9~11, and even more preferably 1:9.5~10.5.
[0056] In this invention, the mixing temperature is preferably 60~80℃, more preferably 65~75℃, and even more preferably 66~74℃; the mixing time is preferably 3~5h, more preferably 3.5~4.5h, and even more preferably 3.8~4.2h; the mixing speed is preferably 200~300rpm, more preferably 220~280rpm, and even more preferably 240~260rpm.
[0057] In this invention, the aggregate is crushed granite.
[0058] In this invention, the aggregate contains components with a particle size of 3~3.75mm and components with a particle size of 3.8~4.25mm.
[0059] In this invention, the mass ratio of the component with a particle size of 3 to 3.75 mm to the component with a particle size of 3.8 to 4.25 mm is preferably 1:1 to 1.5, more preferably 1:1.1 to 1.4, and even more preferably 1:1.2 to 1.3.
[0060] In this invention, the method for preparing the plant fiber includes the following steps:
[0061] The plant fiber is obtained by sequentially subjecting Stipa grandis to alkali treatment and coupling treatment.
[0062] In this invention, the length of the large needlegrass is preferably 2~3.5mm, more preferably 2.5~3mm, and even more preferably 2.6~2.8mm.
[0063] In this invention, the reagent for alkali treatment is a sodium hydroxide solution, and *Stipa grandis* is completely immersed in the sodium hydroxide solution for alkali treatment; the concentration of the sodium hydroxide solution is preferably 2-2.5%, more preferably 2.1-2.4%, and even more preferably 2.2-2.3%; the temperature of the alkali treatment is preferably 60-70°C, more preferably 62-68°C, and even more preferably 64-66°C; the time is preferably 50-60 min, more preferably 52-58 min, and even more preferably 54-56 min.
[0064] In this invention, after the alkali treatment is completed, the mixture is washed with water until neutral and dried, and then a coupling treatment is performed.
[0065] In this invention, the reagent for the coupling treatment is preferably a coupling agent solution, in which the alkali-treated and dried *Stipa grandis* is completely immersed in the coupling agent solution for coupling treatment; the coupling agent is KH-550 and / or KH-570; the concentration of the coupling agent solution is preferably 0.5-1%, more preferably 0.6-0.9%, and even more preferably 0.7-0.8%; the coupling treatment time is preferably 15-30 min, more preferably 20-25 min, and even more preferably 22-23 min.
[0066] In this invention, the specific surface area of the silica sand is preferably ≥1300 cm². 2 / g, further preferred ≥1500cm 2 / g, more preferably ≥1600cm 2 / g.
[0067] In this invention, the water-reducing agent is a polycarboxylate water-reducing agent and / or a naphthalene-based water-reducing agent.
[0068] The present invention also provides a method for preparing the coal mine slag grouting material, comprising the following steps:
[0069] (1) Mix activated coal slag, aggregate, plant fiber and silica sand to obtain dry material;
[0070] (2) Mix the aluminum ash aqueous solution and the mixing water to obtain a wet material;
[0071] (3) Mix the dry material, wet material and water-reducing agent to obtain the coal mine slag grouting material.
[0072] In this invention, the mixing speed in step (1) is preferably 200~300 rpm, more preferably 220~280 rpm, and even more preferably 240~260 rpm; the mixing time is preferably 5~10 min, more preferably 6~9 min, and even more preferably 7~8 min.
[0073] In this invention, the mixing time in step (2) is preferably 60-90s, more preferably 65-85s, and even more preferably 70-80s.
[0074] In this invention, the mixing speed in step (3) is preferably 400~500 rpm, more preferably 420~480 rpm, and even more preferably 440~460 rpm; the mixing time is preferably 2~3 min, more preferably 2.2~2.8 min, and even more preferably 2.4~2.6 min.
[0075] The present invention also provides the application of the coal mine slag grouting material in mine backfilling.
[0076] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0077] Example 1
[0078] Coal mine slag is collected and crushed, wherein the mass ratio of the components with a particle size less than or equal to 0.075 mm, the components with a particle size greater than 0.075 mm and less than or equal to 0.425 mm, the components with a particle size greater than 0.425 mm and less than or equal to 1.18 mm, and the components with a particle size greater than 1.18 mm and less than or equal to 2.75 mm is 25:12:28:33; the coal mine slag is then thermally activated at 650℃ for 2 hours to obtain activated coal mine slag.
[0079] The particle size of aluminum ash was controlled to be 0.2 mm. Aluminum ash and water were mixed at a mass ratio of 1:10 and reacted at 70℃ and 240 rpm for 4 hours to obtain an aluminum ash aqueous solution.
[0080] The aggregate is crushed granite, in which the mass ratio of the component with a particle size of 3~3.75mm to the component with a particle size of 3.8~4.25mm is 1:1.1.
[0081] Collect mature Stipa spp., with a treated length of 2.7 mm; completely immerse in a 2.3% sodium hydroxide solution and treat at 65°C for 50 min; remove, wash with water until neutral, and dry; then prepare a 0.8% KH-550 solution, completely immerse the dried Stipa spp. in the coupling agent solution, and treat for 20 min to obtain plant fiber.
[0082] The specific surface area of silica sand is 1400 cm². 2 / g, the water-reducing agent used is polycarboxylate water-reducing agent.
[0083] Prepare the following raw materials in the indicated weight proportions: 75 parts activated coal slag, 35 parts aluminum ash aqueous solution, 20 parts aggregate, 10 parts plant fiber, 9 parts silica sand, 2 parts water-reducing agent, and 12 parts mixing water.
[0084] The activated coal slag, aggregate, plant fiber and silica sand are mixed and stirred at 280 rpm for 10 min to obtain dry material; then aluminum ash aqueous solution and mixing water are mixed for 80 s to obtain wet material; the dry material, wet material and water reducing agent are mixed and stirred at 450 rpm for 2.5 min to obtain coal slag grouting material.
[0085] Example 2
[0086] Coal mine slag is collected and crushed, wherein the mass ratio of the components with a particle size less than or equal to 0.075 mm, the components with a particle size greater than 0.075 mm and less than or equal to 0.425 mm, the components with a particle size greater than 0.425 mm and less than or equal to 1.18 mm, and the components with a particle size greater than 1.18 mm and less than or equal to 2.75 mm is 22:14:30:32; the coal mine slag is then thermally activated at 620℃ for 1.5 h to obtain activated coal mine slag.
[0087] The particle size of aluminum ash was controlled to be 0.1 mm. Aluminum ash and water were mixed at a mass ratio of 1:8 and reacted at 65℃ and 280 rpm for 3 hours to obtain an aluminum ash aqueous solution.
[0088] The aggregate is crushed granite, in which the mass ratio of the component with a particle size of 3~3.75mm to the component with a particle size of 3.8~4.25mm is 1:1.4.
[0089] Collect mature Stipa spp. fruits, with a length of 2.3 mm after treatment; completely immerse them in a 2% sodium hydroxide solution and treat at 60℃ for 60 min; remove and wash with water until neutral and dry; then prepare a 0.5% KH-570 solution, completely immerse the dried Stipa spp. in the coupling agent solution, and treat for 30 min to obtain plant fiber.
[0090] The specific surface area of silica sand is 1500 cm². 2 / g, naphthalene-based water-reducing agent is used.
[0091] Prepare the following raw materials in the indicated weight proportions: 80 parts activated coal slag, 31 parts aluminum ash aqueous solution, 23 parts aggregate, 9 parts plant fiber, 7 parts silica sand, 2.2 parts water-reducing agent, and 15 parts mixing water.
[0092] Activated coal slag, aggregate, plant fiber and silica sand are mixed and stirred at 300 rpm for 5 min to obtain dry material; then aluminum ash aqueous solution and mixing water are mixed for 60 s to obtain wet material; dry material, wet material and water reducing agent are mixed and stirred at 420 rpm for 3 min to obtain coal slag grouting material.
[0093] Example 3
[0094] Coal mine slag is collected and crushed, wherein the mass ratio of the components with a particle size less than or equal to 0.075 mm, the components with a particle size greater than 0.075 mm and less than or equal to 0.425 mm, the components with a particle size greater than 0.425 mm and less than or equal to 1.18 mm, and the components with a particle size greater than 1.18 mm and less than or equal to 2.75 mm is 29:11:25:33; the coal mine slag is then thermally activated at 680℃ for 2.2 h to obtain activated coal mine slag.
[0095] The particle size of aluminum ash was controlled to be 0.2 mm. Aluminum ash and water were mixed at a mass ratio of 1:12 and reacted at 80℃ and 300 rpm for 5 h to obtain an aluminum ash aqueous solution.
[0096] The aggregate is crushed granite, in which the mass ratio of the component with a particle size of 3~3.75mm to the component with a particle size of 3.8~4.25mm is 1:1.2.
[0097] Collect mature Stipa spp., with a treated length of 3.1 mm; completely immerse in a 2.4% sodium hydroxide solution and treat at 70℃ for 50 min; remove, wash with water until neutral, and dry; then prepare a 0.9% KH-570 solution, completely immerse the dried Stipa spp. in the coupling agent solution, and treat for 20 min to obtain plant fiber.
[0098] The specific surface area of silica sand is 1600 cm². 2 / g, naphthalene-based water-reducing agent is used.
[0099] Prepare the following raw materials in the indicated weight proportions: 71 parts activated coal slag, 40 parts aluminum ash aqueous solution, 19 parts aggregate, 11 parts plant fiber, 9 parts silica sand, 2.5 parts water-reducing agent, and 14 parts mixing water.
[0100] The activated coal slag, aggregate, plant fiber and silica sand are mixed and stirred at 260 rpm for 10 min to obtain dry material; then aluminum ash aqueous solution and mixing water are mixed for 80 s to obtain wet material; the dry material, wet material and water reducing agent are mixed and stirred at 500 rpm for 2 min to obtain coal slag grouting material.
[0101] Comparative Example 1
[0102] Compared with Example 1, the difference in Comparative Example 1 is that the coal mine slag is not sized by particle size distribution, and all components are composed of particles with a particle size greater than 0.075 mm and less than or equal to 0.425 mm. The other parameters are the same as those in Example 1.
[0103] Comparative Example 2
[0104] Compared with Example 1, Comparative Example 2 differs in that aluminum ash is replaced with sodium hydroxide, while the other parameters are the same as in Example 1.
[0105] Comparative Example 3
[0106] Compared with Example 1, Comparative Example 3 does not contain plant fiber, and the corresponding activated coal slag mass fraction is 85 parts. The other parameters are the same as those in Example 1.
[0107] The grouting materials of Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests. The compressive strength at 3 days, 7 days, and 28 days, and the flexural strength at 28 days, were tested according to GB / T17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)". The 28-day drying shrinkage rate was tested according to GB / T50082-2009 "Standard for Test Methods of Long-Term Performance and Durability of Concrete". The fluidity was tested according to GB / T 8077-2023 "Test Method for Homogeneity of Concrete Admixtures". The setting time was tested according to GB / T 1346-2024 "Standard for Test Methods of Standard Consistency Water Requirement, Setting Time and Soundness of Cement". The results are recorded in Table 1.
[0108] Table 1 Performance Test Results
[0109]
[0110] The results of the embodiments show that the grouting material provided by the present invention has excellent mechanical properties, with a 28-day compressive strength of 36.4 MPa, a 28-day flexural strength of 8.7 MPa, and a 28-day shrinkage rate of only 0.05%. Comparative Example 1 shows that although the flowability of the grouting material is improved under the combined particle size distribution, the interlocking effect between materials cannot be achieved, resulting in a significant decrease in compressive strength. Directly using sodium hydroxide for alkaline activation in the prior art results in a fast activation rate and high initial compressive strength; however, because sodium hydroxide does not contain aluminum ions, it cannot participate in the formation of Si-O-Al bond units, leading to a decrease in compressive strength in the later stages. Comparative Example 3 shows that plant fibers play a crucial role in connecting the materials, effectively dispersing external forces and significantly improving flexural strength. The present invention, through reasonable modification and formulation of solid waste, prepares a high-performance grouting material.
[0111] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A coal mine slag grouting material, characterized in that, It is prepared from the following parts by mass of raw materials: 70-80 parts activated coal mine slag, 30-40 parts aluminum ash aqueous solution, 17-25 parts aggregate, 8-12 parts plant fiber, 7-10 parts silica sand, 2-2.5 parts water-reducing agent, and 10-15 parts mixing water; Activated coal mine slag is obtained by thermally activating coal mine slag. Under high temperature, the inert kaolinite minerals in the slag are transformed into amorphous, highly active silicon oxides and aluminum oxides.
2. The coal mine slag grouting material as described in claim 1, characterized in that, The method for preparing activated coal mine slag includes the following steps: The coal mine slag contains components with a particle size of less than or equal to 0.075 mm, components with a particle size greater than 0.075 mm and less than or equal to 0.425 mm, components with a particle size greater than 0.425 mm and less than or equal to 1.18 mm, and components with a particle size greater than 1.18 mm and less than or equal to 2.75 mm. The mass ratio of the components with a particle size less than or equal to 0.075 mm, the components with a particle size greater than 0.075 mm and less than or equal to 0.425 mm, the components with a particle size greater than 0.425 mm and less than or equal to 1.18 mm, and the components with a particle size greater than 1.18 mm and less than or equal to 2.75 mm is 20~30:10~15:25~30:30~35. The thermal activation temperature is 600~700℃, and the time is 1.5~2.5h.
3. The coal mine slag grouting material as described in claim 2, characterized in that, The method for preparing the aluminum ash aqueous solution includes the following steps: Aluminum ash and water are mixed to obtain an aluminum ash aqueous solution; The aluminum ash has a particle size ≤0.2mm; the mass ratio of aluminum ash to water is 1:8~12; The mixing temperature is 60~80℃, the time is 3~5h, and the rotation speed is 200~300rpm.
4. The coal mine slag grouting material as described in claim 3, characterized in that, The aggregate is crushed granite. The aggregate contains components with a particle size of 3~3.75mm and components with a particle size of 3.8~4.25mm; The mass ratio of the component with a particle size of 3~3.75mm to the component with a particle size of 3.8~4.25mm is 1:1~1.
5.
5. The coal mine slag grouting material as described in claim 4, characterized in that, The method for preparing the plant fiber includes the following steps: The plant fiber is obtained by sequentially subjecting Stipa grandis to alkali treatment and coupling treatment. The length of the large needlegrass is 2~3.5mm; The reagent for alkali treatment is sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 2~2.5%; the temperature of alkali treatment is 60~70℃, and the time is 50~60min; The reagent for the coupling treatment is a coupling agent solution, the concentration of the coupling agent solution is 0.5~1%, and the coupling treatment time is 15~30 min; The specific surface area of the silica sand is ≥1300 cm². 2 / g; The water-reducing agent is a polycarboxylate water-reducing agent and / or a naphthalene-based water-reducing agent.
6. The method for preparing the coal mine slag grouting material according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Mix activated coal slag, aggregate, plant fiber and silica sand to obtain dry material; (2) Mix the aluminum ash aqueous solution and the mixing water to obtain a wet material; (3) Mix the dry material, wet material and water-reducing agent to obtain the coal mine slag grouting material.
7. The preparation method of the coal mine slag grouting material as described in claim 6, characterized in that, The mixing speed in step (1) is 200~300 rpm and the time is 5~10 min.
8. The method for preparing the coal mine slag grouting material as described in claim 7, characterized in that, The mixing time in step (2) is 60~90s.
9. The preparation method of the coal mine slag grouting material as described in claim 8, characterized in that, The mixing speed in step (3) is 400~500 rpm and the time is 2~3 min.
10. The application of the coal mine slag grouting material according to any one of claims 1 to 5 in mine backfilling.