Mining coal gangue / polyurethane / water glass composite filling material and preparation method thereof

Abstract

The invention discloses a mining coal gangue / polyurethane / water glass composite filling material and a preparation method thereof, and belongs to the technical field of filling materials, the material is prepared by mixing a component A (water glass, glycerin and a catalyst), a component B (isophorone diisocyanate, polypropylene glycol and a plasticizer), coal gangue and fly ash according to a specific ratio, the preparation method comprises the following steps: respectively preparing the component A and the component B, mixing into slurry, and finally stirring and curing with the coal gangue and the fly ash. The curing time of the material is less than or equal to 124 s, the compressive strength is higher than 70 MPa, and the material is safe, environmentally friendly, free of secondary pollution, outstanding in flame retardance, capable of meeting the industrial standard and suitable for coal mine top-caving area filling, goaf gas plugging and crack air leakage channel plugging.

Description

Technical Field

[0001] This invention belongs to the field of filling material technology, and particularly relates to a coal gangue / polyurethane / water glass composite filling material for mining and its preparation method. Background Technology

[0002] During underground coal mining operations, high-risk coal and rock caves, various cracks, air leakage channels, and goaf areas are highly susceptible to becoming sites for the emission and accumulation of underground gas, posing a significant safety threat. Coal mine filling materials, due to their excellent gas-tightness and foaming properties, are widely used in permanent (temporary) sealing projects in coal mines and tunnels. They are particularly suitable for filling high-risk coal and rock caves, various cracks, and air leakage channels, and can also seal the upper and lower corners of the working face, achieving air leakage prevention and control of gas emission from goaf areas.

[0003] Currently, commonly used filler materials in the coal mining industry mainly fall into two categories: phenolic resins and polyurethanes. While phenolic resin fillers possess outstanding flame-retardant properties, their curing agents are highly acidic, posing a risk of personal injury to workers. Skin contact with spilled material can cause redness, itching, and other discomfort; contact with eyes can lead to blindness in severe cases. Furthermore, residual formaldehyde in phenolic resins can pollute the underground environment, and its poor mechanical properties make it prone to weathering and damage with prolonged use. Polyurethane fillers, on the other hand, possess good expandability and mechanical properties, are non-volatile and non-corrosive, and are safe and reliable. However, they suffer from insufficient flame-retardant properties and are prone to heat accumulation during the reaction process, with internal temperatures reaching over 160°C. In extreme cases, this can lead to smoke and spontaneous combustion risks.

[0004] The safety production industry standard AQ / T1087-2020 sets strict requirements for polymer materials used in coal mine water plugging. Besides meeting mechanical performance indicators such as compressive strength of not less than 50 MPa and shear strength of not less than 20 MPa, it also explicitly requires that the materials possess safety and environmental protection characteristics and must not pollute groundwater. Polyurethane / water glass organic-inorganic composite materials have advantages such as high early strength and high elastic modulus, and have been widely used in underground engineering. However, current research on the modification of this type of composite material mainly focuses on enhancing adhesion and improving toughness, and modified products are mostly suitable for reinforcement scenarios. In the field of mine water plugging, there are still prominent problems such as performance difficulties in meeting industry standards and high production costs. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a coal gangue / polyurethane / water glass composite backfill material for mining and its preparation method. This material has a short curing time, high compressive strength, and meets the safety standards for use in the mining backfill polymer materials industry.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A composite backfill material for mining, consisting of coal gangue / polyurethane / water glass, is composed of component A, component B, coal gangue, and fly ash; wherein, Component A comprises the following raw materials by mass: 10-27 parts water glass, 3 parts glycerol, and 1 part catalyst; Component B comprises the following raw materials by mass: 10-27 parts of isophorone diisocyanate, 18 parts of polyol, and 9 parts of plasticizer.

[0007] The core reaction mechanism of this invention is the synergistic cross-linking reaction between water glass and polyurethane, the compatibility regulation of the catalyst, and the participation of active hydroxyl groups from coal gangue. Through the chemical interactions between multiple components, a stable composite system is constructed, ultimately achieving multi-dimensional performance improvements in mechanical properties, curing efficiency, safety, and environmental friendliness. Specifically, the Si-O bonds in the water glass molecules have high reactivity and can chemically react with the active groups in the polyurethane chain segments, introducing the inorganic Si-O structure into the organic polyurethane molecular chain. This cross-component chemical bonding forms an "organic-inorganic interpenetrating network structure," significantly increasing the cross-linking density of the system, making the internal structure of the material denser and the force transmission more uniform. The introduced catalyst can significantly improve the hydrophilicity of isocyanate, breaking down the interfacial tension barrier between it and water glass (inorganic phase). This effect allows component A (water glass system) and component B (polyurethane system) to form a homogeneous and stable solution after mixing, avoiding phase separation and ensuring that the reaction occurs uniformly within the system, thus improving the isotropic properties of the material. The active hydroxyl groups generated by the reaction of SiO2 in coal gangue with water can replace some of the silanol groups in water glass, participating in the cross-linking reaction of polyurethane. On one hand, this replenishes the active sites for the cross-linking reaction, further densifying the network structure; on the other hand, through the chemical bonding of "inorganic filler-organic matrix," it enhances the bonding force between coal gangue and the polyurethane / water glass matrix, reducing internal defects. As an inorganic filler phase, fly ash forms a synergistic reinforcing system with the water glass-polyurethane matrix and coal gangue, filling internal voids and improving structural density. Fly ash itself is industrial solid waste; through chemical bonding and physical encapsulation, it is stably bound within the cross-linked network, preventing the leaching of internal heavy metals and completely solving the groundwater pollution problem that may be caused by the utilization of coal-based solid waste, meeting industry environmental standards. Moreover, as an inorganic inert component, fly ash reduces the proportion of organic phase in the material, inhibits the thermal motion of molecular chains, reduces heat accumulation during the reaction process, and keeps the maximum reaction temperature of the material below 90°C. Combined with the flame-retardant properties of water glass, it achieves a "non-flammable" effect and avoids the risk of high-temperature spontaneous combustion of traditional polyurethane materials.

[0008] Furthermore, the mass ratio of component A to component B is 1:(1.5-1.9).

[0009] This ratio breaks down the interfacial tension barrier between the two phases, ensuring that component A (water glass system) and component B (polyurethane system) form a homogeneous and stable solution after mixing, thus preventing phase separation. It also ensures uniform crosslinking, improves the isotropic properties of the material, and guarantees that compressive strength, shear strength, and other indicators consistently meet the requirements of industry standard AQ / T1087-2020.

[0010] Furthermore, the mass ratio of the sum of component A and component B to coal gangue and fly ash is 1:20:80.

[0011] This invention specifies a mass ratio of slurry to coal gangue and fly ash of 1:20:80, maximizing the utilization of industrial solid waste and significantly reducing material production costs. The coal gangue and fly ash form a synergistic reinforcing system, filling internal voids and improving structural density; simultaneously, they bind heavy metals in the solid waste through chemical bonding and physical encapsulation, preventing groundwater pollution and meeting environmental protection requirements.

[0012] Furthermore, the fineness of the coal gangue is ≤500 mesh.

[0013] This invention limits the fineness of coal gangue to ≤500 mesh, increasing its specific surface area and allowing it to generate more active hydroxyl groups upon contact with water. These active hydroxyl groups can fully participate in the polyurethane crosslinking reaction, supplementing active sites and creating a dense network structure. Simultaneously, they enhance the bonding force between the coal gangue and the matrix, further shortening the curing time, improving the material's mechanical strength, and avoiding internal defects caused by excessively large particles.

[0014] During coal mining, low-calorific-value rocks (such as shale and sandstone) associated with the coal seam are stripped away during mining operations, forming industrial solid waste, coal gangue. Its main components are metal oxides such as SiO2 and Al2O3. When SiO2 comes into contact with water, it forms a large number of active hydroxyl groups. These active hydroxyl groups can replace some of the silanols in water glass in the polyurethane reaction, thereby accelerating the reaction rate, shortening the curing time, optimizing the overall performance of the material, and effectively reducing the material's production cost.

[0015] Furthermore, the modulus of the water glass is 3.09-3.15, and the Baume degree is 35-40.

[0016] This invention specifies water glass with a modulus of 3.09-3.15 and a Baumé degree of 35-40. Water glass with these parameters exhibits optimal Si-O bond reactivity, enabling efficient cross-linking reactions with active groups in polyurethane segments. This ensures the stable formation of the "organic-inorganic interpenetrating network structure," improving the material's early strength and elastic modulus, while also enhancing flame retardant properties, making it suitable for the high-temperature, high-risk environments required for mining.

[0017] Furthermore, the catalyst is selected from one or a combination of two of dibutyltin dilaurate, stannous octoate, and N,N-dimethylethylaminoethylene glycol.

[0018] This invention limits the specific range of catalyst selection. The selected catalyst can significantly improve the hydrophilicity of isocyanate and optimize the compatibility of component A and component B. At the same time, it precisely controls the crosslinking reaction rate to avoid performance defects caused by excessively fast or slow reactions, ensuring a uniform and controllable curing process, and further improving the stability and reliability of the material's mechanical properties.

[0019] Furthermore, the polyol is polypropylene glycol.

[0020] Polypropylene glycol (PPG) exhibits strong compatibility with isophorone diisocyanate (IOD) in its molecular structure, enabling the formation of structurally stable polyurethane segments. Synergistically, the inorganic structure of water glass balances the material's rigidity and toughness, overcoming the brittleness inherent in conventional polyurethane / water glass composites and enhancing the material's impact resistance and service life in coal mine backfilling and sealing applications.

[0021] Furthermore, the plasticizer is selected from one or a combination of two of dioctyl phthalate, chlorinated paraffin, and sodium tripolyphosphate.

[0022] This invention limits the range of plasticizers that can be selected to optimize the flexibility of the material's internal molecular chains, improving processing performance and ease of construction. Simultaneously, it does not affect the material's flame retardancy and environmental friendliness, avoiding problems such as high-temperature decomposition and release of toxic gases caused by improper plasticizer selection, thus ensuring the safety of underground construction personnel and the cleanliness of the underground environment.

[0023] The present invention also provides a method for preparing the above-mentioned coal gangue / polyurethane / water glass composite backfill material for mining, comprising the following steps: Weigh the raw materials, mix water glass, glycerol and catalyst evenly to obtain component A; Isophorone diisocyanate, polyol and plasticizer are mixed and stirred evenly to obtain component B; Component A and component B are mixed and stirred evenly to obtain a mixed slurry; The mixed slurry is mixed evenly with coal gangue and fly ash, and allowed to stand and solidify to obtain a coal gangue / polyurethane / water glass composite filling material for mining.

[0024] This invention provides a stepwise preparation process, in which components A and B are prepared separately before mixing, ensuring uniform mixing of raw materials within each component and avoiding incomplete local reactions. Subsequent adjustments to the mixing parameters with coal gangue and fly ash guarantee overall uniform mixing of the materials, and the static curing process is stable and controllable. The process is simple, requires no complex equipment, enables large-scale production, and can reliably reproduce the excellent performance of the product.

[0025] The present invention also provides an application of the above-mentioned coal gangue / polyurethane / water glass composite filling material in filling coal and rock caves in high-risk coal mine areas, sealing gas in coal mine goaf areas, and plugging air leakage channels in fissures.

[0026] This invention clearly defines the core application scenarios of the material. Its short curing time and high compressive strength characteristics allow for rapid filling of coal and rock voids in high-risk coal mine areas, promptly eliminating safety hazards. Its excellent gas-tightness and flame-retardant properties effectively seal gas in goaf areas and plug leaking fissures and air passages. It is suitable for complex underground coal mine conditions, solving core safety problems such as gas accumulation and air leakage, and meeting the core requirements of permanent (temporary) sealing projects in coal mines.

[0027] Compared with the prior art, the present invention has the following advantages and technical effects: 1. Convenient preparation and excellent mechanical properties: The composite grouting material of this invention has a simple preparation process, requiring no complex equipment or cumbersome procedures. Its curing time is less than 124s, and its compressive strength is higher than 70MPa and shear strength is higher than 30MPa. It effectively overcomes the technical pain points of conventional polyurethane / water glass composite materials, such as high brittleness and insufficient shear strength, and can fully meet the mechanical performance requirements of mine filling and reinforcement.

[0028] 2. Safe, environmentally friendly, and compliant with industry standards: The raw materials used in the material have a mild odor, do not contain volatile solvents, and do not produce toxic gases during the reaction and use process. Furthermore, the material does not leach heavy metals from fly ash, thus avoiding groundwater pollution and completely solving the secondary pollution problems that may arise from the utilization of conventional coal-based solid waste. It fully complies with the industry safety and environmental protection standards for coal mine filling and reinforcement materials and mining filling polymer materials.

[0029] 3. Outstanding flame retardant performance: The maximum temperature during the material reaction process is below 90℃. Compared with the high temperature risk of traditional polyurethane filling materials, its thermal stability is significantly improved, and it has strong flame retardant performance, which can effectively reduce safety hazards when used in underground coal mines. Attached Figure Description

[0030] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the process for preparing a coal gangue / polyurethane / water glass composite backing material for mining, according to an embodiment of the present invention. Detailed Implementation

[0031] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0032] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0033] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0034] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0035] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0036] Figure 1 This is a schematic diagram of the process for preparing a coal gangue / polyurethane / water glass composite backing material for mining, according to an embodiment of the present invention.

[0037] This invention provides a composite filling material for coal gangue / polyurethane / water glass used in mining, and the specific preparation steps are as follows: 1. Raw material pretreatment and preparation 1) Select industrial solid waste coal gangue (mainly composed of metal oxides such as SiO2 and Al2O3), crush it to a fineness of ≤500 mesh, place it in a ceramic crucible, and dry it at a constant temperature of 120-160℃ for 2-24 hours. After drying, seal and store it for later use. This invention does not have a special limitation on the source of coal gangue, and commercially available coal gangue can be selected. For example, in the following preferred embodiment of this invention, coal gangue from Dayugou Coal Mine in Gongyi City, Henan Province, with a particle size of 5-15mm is selected.

[0038] 2) Select Class II fly ash. This invention does not have a special limitation on the source of fly ash, and commercially available fly ash can be selected. For example, in the following preferred embodiments of this invention, the fly ash selected is uncalcined fly ash from Henan Datang Thermal Power Plant with a fineness of 16%.

[0039] 3) Prepare the raw materials for each component and clarify the specifications: Water glass: Molecular formula is The modulus is 3.09-3.15 and the Baumé degree is 35-40. The present invention does not have a special limitation on the source of water glass, and commercially available water glass can be selected. For example, in the following preferred embodiments of the present invention, the raw materials were purchased from Tianjin Huasheng Technology Co., Ltd.

[0040] Prepolymer: Isophorone diisocyanate (IPDI). For example, in the following preferred embodiments of the present invention, the raw materials were purchased from Tianjin Huasheng Technology Co., Ltd. and Shanghai Aladdin Biochemical Technology Co., Ltd., and the NCO content was 39.6 wt%.

[0041] Catalyst: Selected from one or a combination of two of dibutyltin dilaurate, stannous octoate and N,N-dimethylethylaminoethylene glycol; exemplary, in the following preferred embodiments of the present invention, the raw materials were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0042] Polyol: Polypropylene glycol PPG2000; For example, in the following preferred embodiments of the present invention, the raw material was purchased from Shandong Yousuo Chemical Technology Co., Ltd., with a viscosity (20°C, MPa.s) of 497.3 and a hydroxyl value of 55 mg KOH / g.

[0043] Plasticizer: selected from one or a combination of two of dioctyl phthalate, chlorinated paraffin, and sodium tripolyphosphate; exemplary, in the following preferred embodiments of the present invention, the plasticizer is a mixture of dioctyl phthalate and chlorinated paraffin in a mass ratio of 3:6, both purchased from Tianjin Kemeo Chemical Reagent Co., Ltd. The remaining raw materials (glycerin, etc.) are conventional industrial-grade raw materials.

[0044] 2. Preparation of component A Weigh the raw materials according to the following proportions by weight: 10-27 parts water glass (e.g., 10 or 27 parts), 3 parts glycerol, and 1 part catalyst. Add the above raw materials to a mixing vessel and stir for 15 minutes at a constant temperature of 40℃ and a rotation speed of 200 r / min. After mixing evenly, seal and store to obtain component A. If the proportions of water glass, glycerol, and catalyst are not within the above ranges, severe foaming will occur, resulting in a significant decrease in the mechanical strength of the obtained composite filling material.

[0045] 3. Preparation of component B Weigh the following raw materials according to the specified mass percentages: 10-27 parts of isophorone diisocyanate (e.g., 10 or 27 parts), 18 parts of polyol, and 9 parts of plasticizer. Add the above raw materials to a mixing vessel and stir for 15 minutes at a constant temperature of 40℃ and a rotation speed of 200 r / min. After mixing evenly, seal and store to obtain component B.

[0046] 4. Preparation of mixed slurry Take out the sealed components A and B according to the mass ratio of component A to component B of 1:(1.5-1.9) (e.g., the mass ratio of A to component B is 1:1.5, 1:1.7, or 1:1.9), put them into a mixing device, and stir at 300 r / min for 30 min until they are evenly mixed to obtain a mixed slurry. If the coal gangue content is further increased, the mechanical properties of the composite backfill material will be reduced.

[0047] 5. Mixing and curing molding According to the mass ratio of mixed slurry (the sum of component A and component B): coal gangue: fly ash = 1:20:80, the pretreated coal gangue and fly ash are added to the above mixed slurry and stirred in a mixer at 450 r / min for 1 min to ensure uniform mixing. The mixed material is then allowed to stand and solidify to finally obtain a mining coal gangue / polyurethane / water glass composite filling material.

[0048] The aforementioned coal gangue / polyurethane / water glass composite filling material can be used for filling coal and rock caves in high-risk coal mine areas, sealing gas in coal mine goaf areas, and plugging leaks in fissures and air passages.

[0049] Unless otherwise specified, "room temperature" in this invention refers to 25±2℃.

[0050] Unless otherwise specified, the term "parts" in this invention refers to parts by weight.

[0051] All raw materials used in this invention were purchased from the market.

[0052] The technical solution of the present invention will be further illustrated by the following embodiments.

[0053] In the following examples and comparative examples, the coal gangue used had a fineness of ≤500 mesh and was obtained by constant temperature drying at 120-160℃ for 2-24 hours in a ceramic crucible; the water glass had a modulus of 3.11 and a Baume degree of 40.

[0054] Example 1 A composite backfill material for mining coal gangue / polyurethane / water glass, the raw materials of which are: Component A: 27 parts water glass, 3 parts glycerol, 1 part catalyst (0.5 parts dibutyltin dilaurate, 0.5 parts N,N-dimethylethylaminoethylene glycol); Component B: 27 parts isophorone diisocyanate, 18 parts polypropylene glycol, and 9 parts plasticizer (3 parts dioctyl phthalate and 6 parts chlorinated paraffin).

[0055] A method for preparing a composite backfill material for mining coal gangue / polyurethane / water glass, comprising the following steps: 1) Preparation of component A: Weigh water glass, glycerol and catalyst according to the above mass proportions and add them to a mixing vessel. Stir for 15 minutes at a constant temperature of 40℃ and a speed of 200r / min. After mixing evenly, component A is obtained and sealed for storage. 2) Preparation of component B: Weigh isophorone diisocyanate, polypropylene glycol and plasticizer according to the above mass proportions and add them to the mixing vessel. Stir for 15 minutes at a constant temperature of 40℃ and a speed of 200r / min. After mixing evenly, component B is obtained and sealed for storage. 3) Preparation of mixed slurry: Mix component A and component B at a mass ratio of 1:1.7 and put them into a mixing device. Stir at a speed of 300 r / min for 30 min. After mixing evenly, a mixed slurry is obtained. 4) Preparation of composite filling material: According to the mass ratio of mixed slurry: coal gangue: fly ash = 1:20:80, the pretreated coal gangue and fly ash are added to the mixed slurry and stirred in a stirring device at a speed of 450 r / min for 1 min. The mixed material is then allowed to stand and solidify to finally obtain the mining coal gangue / polyurethane / water glass composite filling material.

[0056] Example 2 A composite backfill material for mining coal gangue / polyurethane / water glass, the raw materials of which are: Component A: 10 parts water glass, 3 parts glycerol, 1 part catalyst (0.5 parts dibutyltin dilaurate, 0.5 parts N,N-dimethylethylaminoethylene glycol); Component B: 27 parts isophorone diisocyanate, 18 parts polypropylene glycol, and 9 parts plasticizer (3 parts dioctyl phthalate and 6 parts chlorinated paraffin).

[0057] A method for preparing a composite backfill material for mining coal gangue / polyurethane / water glass, comprising the following steps: 1) Preparation of component A: Weigh water glass, glycerol and catalyst according to the above mass proportions and add them to a mixing vessel. Stir for 15 minutes at a constant temperature of 40℃ and a speed of 200r / min. After mixing evenly, component A is obtained and sealed for storage. 2) Preparation of component B: Weigh isophorone diisocyanate, polypropylene glycol and plasticizer according to the above mass proportions and add them to the mixing vessel. Stir for 15 minutes at a constant temperature of 40℃ and a speed of 200r / min. After mixing evenly, component B is obtained and sealed for storage. 3) Preparation of mixed slurry: Mix component A and component B at a mass ratio of 1:1.9 and put them into a mixing device. Stir at a speed of 300 r / min for 30 min. After mixing evenly, a mixed slurry is obtained. 4) Preparation of composite filling material: According to the mass ratio of mixed slurry: coal gangue: fly ash = 1:20:80, the pretreated coal gangue and fly ash are added to the mixed slurry and stirred in a stirring device at a speed of 450 r / min for 1 min. The mixed material is then allowed to stand and solidify to finally obtain the mining coal gangue / polyurethane / water glass composite filling material.

[0058] Same as Example 1, except that the mass ratio of component A to component B is 1:1.9.

[0059] Example 3 A composite backfill material for mining coal gangue / polyurethane / water glass, the raw materials of which are: Component A: 27 parts water glass, 3 parts glycerol, 1 part catalyst (0.5 parts dibutyltin dilaurate, 0.5 parts N,N-dimethylethylaminoethylene glycol); Component B: 10 parts isophorone diisocyanate, 18 parts polypropylene glycol, and 9 parts plasticizer (3 parts dioctyl phthalate and 6 parts chlorinated paraffin).

[0060] A method for preparing a composite backfill material for mining coal gangue / polyurethane / water glass, comprising the following steps: 1) Preparation of component A: Weigh water glass, glycerol and catalyst according to the above mass proportions and add them to a mixing vessel. Stir for 15 minutes at a constant temperature of 40℃ and a speed of 200r / min. After mixing evenly, component A is obtained and sealed for storage. 2) Preparation of component B: Weigh isophorone diisocyanate, polypropylene glycol and plasticizer according to the above mass proportions and add them to the mixing vessel. Stir for 15 minutes at a constant temperature of 40℃ and a speed of 200r / min. After mixing evenly, component B is obtained and sealed for storage. 3) Preparation of mixed slurry: Mix component A and component B at a mass ratio of 1:1.5 and put them into a mixing device. Stir at a speed of 300 r / min for 30 min. After mixing evenly, a mixed slurry is obtained. 4) Preparation of composite filling material: According to the mass ratio of mixed slurry: coal gangue: fly ash = 1:20:80, the pretreated coal gangue and fly ash are added to the mixed slurry and stirred in a stirring device at a speed of 450 r / min for 1 min. The mixed material is then allowed to stand and solidify to finally obtain the mining coal gangue / polyurethane / water glass composite filling material.

[0061] Comparative Example 1 Same as Example 1, except that no catalyst is added to component A.

[0062] Comparative Example 2 Preparation of a traditional polyurethane filling material: 1) Raw materials for preparation: including 27 parts isophorone diisocyanate, 18 parts polypropylene glycol, 9 parts plasticizer (3 parts dioctyl phthalate, 6 parts chlorinated paraffin), 3 parts glycerin, and 1 part catalyst (0.5 parts dibutyltin dilaurate, 0.5 parts N,N-dimethylethylaminoethylene glycol); 2) Preparation of mixed slurry: Weigh the raw materials according to the above mass proportions and add them to the mixing vessel. Stir for 15 minutes at a constant temperature of 40℃ and a rotation speed of 200r / min. After mixing evenly, the traditional polyurethane filling material slurry is obtained. 3) Preparation of composite filling material: According to the mass ratio of mixed slurry: coal gangue: fly ash = 1:20:80, the pretreated coal gangue and fly ash are added to the mixed slurry and stirred in a stirring device at a speed of 450 r / min for 1 min. The mixed material is then allowed to stand and solidify to finally obtain the mining polyurethane composite filling material.

[0063] Comparative Example 3 Component A: 27 parts water glass, 3 parts glycerol, 1 part catalyst (0.5 parts dibutyltin dilaurate, 0.5 parts N,N-dimethylethylaminoethylene glycol); Component B: 35 parts isophorone diisocyanate, 18 parts polypropylene glycol, and 9 parts plasticizer (3 parts dioctyl phthalate and 6 parts chlorinated paraffin).

[0064] A method for preparing a composite backfill material for mining coal gangue / polyurethane / water glass, comprising the following steps: 1) Preparation of component A: Weigh water glass, glycerol and catalyst according to the above mass proportions and add them to a mixing vessel. Stir for 15 minutes at a constant temperature of 40℃ and a speed of 200r / min. After mixing evenly, component A is obtained and sealed for storage. 2) Preparation of component B: Weigh isophorone diisocyanate, polypropylene glycol and plasticizer according to the above mass proportions and add them to the mixing vessel. Stir for 15 minutes at a constant temperature of 40℃ and a speed of 200r / min. After mixing evenly, component B is obtained and sealed for storage. 3) Preparation of mixed slurry: Mix component A and component B at a mass ratio of 1:2 and put them into a mixing device. Stir at a speed of 300 r / min for 30 min. After mixing evenly, a mixed slurry is obtained. 4) Preparation of composite filling material: According to the mass ratio of mixed slurry: coal gangue: fly ash = 1:20:80, the pretreated coal gangue and fly ash are added to the mixed slurry and stirred in a stirring device at a speed of 450 r / min for 1 min. The mixed material is then allowed to stand and solidify to finally obtain the mining coal gangue / polyurethane / water glass composite filling material.

[0065] Comparative Example 4 Component A: 27 parts water glass, 3 parts glycerol, 1 part catalyst (0.5 parts dibutyltin dilaurate, 0.5 parts N,N-dimethylethylaminoethylene glycol); Component B: 22 parts isophorone diisocyanate, 6 parts polypropylene glycol, 3 parts plasticizer (1 part dioctyl phthalate, 2 parts chlorinated paraffin).

[0066] A method for preparing a composite backfill material for mining coal gangue / polyurethane / water glass, comprising the following steps: 1) Preparation of component A: Weigh water glass, glycerol and catalyst according to the above mass proportions and add them to a mixing vessel. Stir for 15 minutes at a constant temperature of 40℃ and a speed of 200r / min. After mixing evenly, component A is obtained and sealed for storage. 2) Preparation of component B: Weigh isophorone diisocyanate, polypropylene glycol and plasticizer according to the above mass proportions and add them to the mixing vessel. Stir for 15 minutes at a constant temperature of 40℃ and a speed of 200r / min. After mixing evenly, component B is obtained and sealed for storage. 3) Preparation of mixed slurry: Mix component A and component B at a mass ratio of 1:1.7 and put them into a mixing device. Stir at a speed of 300 r / min for 30 min. After mixing evenly, a mixed slurry is obtained. 4) Preparation of composite filling material: According to the mass ratio of mixed slurry: coal gangue: fly ash = 1:20:80, the pretreated coal gangue and fly ash are added to the mixed slurry and stirred in a stirring device at a speed of 450 r / min for 1 min. The mixed material is then allowed to stand and solidify to finally obtain the mining coal gangue / polyurethane / water glass composite filling material.

[0067] Comparative Example 5 A composite backfill material for mining coal gangue / polyurethane / water glass, the raw materials of which are: Component A: 27 parts water glass, 3 parts glycerol, 1 part catalyst (0.5 parts dibutyltin dilaurate, 0.5 parts N,N-dimethylethylaminoethylene glycol); Component B: 27 parts isophorone diisocyanate, 18 parts polypropylene glycol, and 9 parts plasticizer (3 parts dioctyl phthalate and 6 parts chlorinated paraffin).

[0068] A method for preparing a composite backfill material for mining coal gangue / polyurethane / water glass, comprising the following steps: 1) Preparation of component A: Weigh water glass, glycerol and catalyst according to the above mass proportions and add them to a mixing vessel. Stir for 15 minutes at a constant temperature of 40℃ and a speed of 200r / min. After mixing evenly, component A is obtained and sealed for storage. 2) Preparation of component B: Weigh isophorone diisocyanate, polypropylene glycol and plasticizer according to the above mass proportions and add them to the mixing vessel. Stir for 15 minutes at a constant temperature of 40℃ and a speed of 200r / min. After mixing evenly, component B is obtained and sealed for storage. 3) Preparation of mixed slurry: Mix component A and component B at a mass ratio of 1:1.7 and put them into a mixing device. Stir at a speed of 300 r / min for 30 min. After mixing evenly, a mixed slurry is obtained. 4) Preparation of composite filling material: According to the mass ratio of mixed slurry to coal gangue = 1:20, the pretreated coal gangue is added to the mixed slurry and stirred in a stirring device at a speed of 450 r / min for 1 min. The mixed material is then allowed to stand and solidify to finally obtain the mining coal gangue / polyurethane / water glass composite filling material.

[0069] Performance testing: The materials prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to performance tests according to the AQ / T1087-2020 standard, and the test results are shown in Table 1.

[0070] Table 1 Performance test results of different materials As shown in Table 1, compared with traditional polyurethane filling materials (Comparative Example 2), the compressive strength of the coal gangue / polyurethane / water glass composite filling materials prepared in Examples 1-3 of this invention is significantly enhanced, all exceeding 50 MPa. The curing time meets the requirements of the industry safety standard "Polymer Materials for Water Blocking in Mines AQ / T1087-2020". Moreover, the production cost and the maximum reaction temperature are significantly reduced, and all performance characteristics are superior to traditional polyurethane filling materials.

[0071] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A composite filling material for mining coal gangue / polyurethane / water glass, characterized in that, It is composed of component A, component B, coal gangue and fly ash; wherein, Component A comprises the following raw materials by mass: 10-27 parts water glass, 3 parts glycerol and 1 part catalyst; Component B comprises the following raw materials by mass: 10-27 parts of isophorone diisocyanate, 18 parts of polyol, and 9 parts of plasticizer.

2. The mining gangue / polyurethane / water glass composite backfill material according to claim 1, characterized in that, The mass ratio of component A to component B is 1:(1.5-1.9).

3. The mining gangue / polyurethane / water glass composite backfill material according to claim 1, characterized in that, The total mass ratio of component A and component B to coal gangue and fly ash is 1:20:

80.

4. The mining coal gangue / polyurethane / water glass composite backfill material according to claim 3, characterized in that, The fineness of the coal gangue is ≤500 mesh.

5. The mining gangue / polyurethane / water glass composite backfill material according to claim 1, characterized in that, The water glass has a modulus of 3.09-3.15 and a Baume degree of 35-40.

6. The mining gangue / polyurethane / water glass composite backfill material according to claim 1, characterized in that, The catalyst is selected from one or a combination of two of dibutyltin dilaurate, stannous octoate, and N,N-dimethylethylaminoethylene glycol.

7. The mining gangue / polyurethane / water glass composite backfill material according to claim 1, characterized in that, The polyol is polypropylene glycol.

8. The mining gangue / polyurethane / water glass composite backfill material according to claim 1, characterized in that, The plasticizer is selected from one or a combination of two of dioctyl phthalate, chlorinated paraffin, and sodium tripolyphosphate.

9. A method for preparing a mine coal gangue / polyurethane / water glass composite backfill material as described in any one of claims 1-8, characterized in that, Includes the following steps: Weigh the raw materials, mix water glass, glycerol and catalyst evenly to obtain component A; Isophorone diisocyanate, polyol and plasticizer are mixed and stirred evenly to obtain component B; Component A and component B are mixed and stirred evenly to obtain a mixed slurry; The mixed slurry is mixed evenly with coal gangue and fly ash, and allowed to stand and solidify to obtain a coal gangue / polyurethane / water glass composite filling material for mining.

10. The application of a coal gangue / polyurethane / water glass composite filling material as described in any one of claims 1-8 in filling coal and rock caves in high-risk coal mine areas, sealing gas in coal mine goaf areas, and plugging air leakage channels in fissures.

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