Coal mine underground airtight air leakage fissure sealing material and preparation method and sealing method thereof

Abstract

The application provides a coal mine underground airtight air leakage fissure sealing material and a preparation method and a sealing method thereof. The coal mine underground airtight air leakage fissure sealing material comprises a first component and a second component which are independently arranged. The first component comprises first fly ash, first clay and first straw with a mass ratio of (8-12):(8-12):(0.8-1.2). The second component comprises second fly ash, second clay and second straw with a mass ratio of (12-18):(28-42):(0.8-1.2). The coal mine underground airtight air leakage fissure sealing material can meet different requirements of the bottom 'caulking' and the top 'protection' of the coal mine underground airtight air leakage fissure by controlling the fly ash and clay proportion in the independently arranged first component and the second component. Meanwhile, the resource utilization of the fly ash and the straw realizes 'waste into treasure', and the three components are matched with the clay which is convenient to obtain, so that the raw material cost is significantly reduced.

Description

Technical Field

[0001] This application relates to the field of coal mine safety engineering technology, and in particular to a sealing material for sealing air-leaking fissures in underground coal mines and its preparation method, as well as a sealing method for sealing air-leaking fissures in underground coal mines. Background Technology

[0002] In underground coal mining operations, sealed structures are critical facilities for ensuring production safety. They are mainly used to isolate non-working areas such as goafs and abandoned roadways, preventing the spread of toxic and harmful gases such as methane, carbon monoxide, and hydrogen sulfide accumulated in these areas to the personnel working areas. They also block air leaks to prevent spontaneous combustion of residual coal in the goafs. However, the underground geological environment is complex and constantly changing. During service, sealed structures are highly susceptible to fractures caused by surrounding rock stress. These fractures become the main channels for the leakage of harmful gases and air leaks, posing a continuous threat to mine safety.

[0003] Specifically, the impact of surrounding rock stress changes on sealing is unavoidable. On the one hand, mining activities during coal mining cause a redistribution of stress in the surrounding rock mass, leading to tensile or shear deformation at the contact surface between the sealing wall and the surrounding rock, as well as within the wall itself, resulting in micro-cracks. On the other hand, long-term factors such as underground temperature changes, groundwater erosion, and rock creep can cause these initial micro-cracks to gradually expand, forming through-hole ventilation channels. The core characteristic of these cracks is that they "leakage is small but persistent"—while they may not directly cause large-scale safety accidents in the short term, they can lead to a continuous and slow influx of harmful gases into the working roadway from the sealed area. Over time, the concentration of harmful gases in the working area will gradually increase. When the concentration of gases such as methane reaches the safety alarm threshold, it will trigger an alarm from the underground gas sensor, forcing the working face to stop for investigation. This not only seriously affects mining efficiency but may also cause uncontrollable safety risks due to fluctuations in gas concentration.

[0004] Existing methods for addressing the aforementioned crack problems have significant drawbacks. Traditional solutions typically require dismantling and rebuilding the existing sealing structure if the cracks are severe or leakage increases. This process necessitates the use of multiple sets of equipment for tunneling, support, and pouring, and requires temporary closure of the work area. Reconstruction of a single sealing point is time-consuming and labor-intensive, significantly increasing mine production costs. If localized repairs are used, the sealing materials often fail to meet practical needs: cement-based sealing materials, while strong, are expensive and brittle after hardening, unable to adapt to minor deformations in the surrounding rock, and prone to secondary cracking; pure loess or fly ash grouting materials have poor adhesion, shrink easily after drying, have a short sealing period, and require frequent replenishment; while polymer gel materials offer good sealing performance, they are expensive and require specialized equipment for application, making widespread underground deployment difficult.

[0005] Therefore, in the current field of sealing and crack treatment in underground coal mines, there is an urgent need for a sealing material that has a long-lasting sealing effect, low cost, and is easy to operate. Summary of the Invention

[0006] In view of this, one objective of this application is to provide a sealing material for air-leaking fissures in underground coal mines. By controlling the proportions of fly ash and clay in the independently set first and second components, it can meet the different needs of "filling" the bottom layer and "protecting" the top layer of air-leaking fissures in underground coal mines. Simultaneously, the resource utilization of fly ash (coal-based solid waste) and straw (agricultural waste) achieves "turning waste into treasure," and combined with readily available clay, the three synergistically significantly reduce raw material costs. This sealing material for air-leaking fissures in underground coal mines fully meets the requirements of green mine construction, simultaneously improving environmental and economic benefits, forming a virtuous cycle of "treating waste with waste."

[0007] Another objective of this application is to provide a method for preparing a sealing material for air-leaking cracks in underground coal mines.

[0008] Another objective of this application is to provide a method for sealing air-leaking fissures in underground coal mines.

[0009] To achieve the above objectives, the first aspect of this application proposes a sealing material for air-leaking fissures in underground coal mines, comprising a first component and a second component that are independently configured. The first component comprises first fly ash, first clay, and first straw, and the mass ratio of the first fly ash, first clay, and first straw is (8-12):(8-12):(0.8-1.2). The second component includes second fly ash, second clay and second straw, and the mass ratio of the second fly ash, second clay and second straw is (12-18):(28-42):(0.8-1.2).

[0010] The sealing material for air-leaking cracks in underground coal mines described in this application can bring at least the following beneficial effects: By controlling the proportions of fly ash and clay in the independently configured first and second components, the different needs of "filling" the bottom layer and "protecting" the top layer of sealed air-leaking fissures in underground coal mines can be met. Simultaneously, the resource utilization of fly ash (coal-based solid waste) and straw (agricultural waste) achieves "turning waste into treasure," and combined with readily available clay, the three work synergistically to significantly reduce raw material costs. This underground air-leaking fissure sealing material fully meets the requirements of green mine construction, simultaneously improving environmental and economic benefits, forming a virtuous cycle of "treating waste with waste."

[0011] In some embodiments, the mass content of the first fly ash and the first clay in the first component is equal.

[0012] In some embodiments, the mass ratio of the first fly ash, the first clay, and the first straw is 10:10:1.

[0013] In some embodiments, the mass ratio of the second fly ash, the second clay, and the second straw is 15:35:1.

[0014] In some embodiments, the first component further includes a first solvent, wherein the first solvent comprises 7-10% by mass in the first component.

[0015] In some embodiments, the first component further includes a thickener, which includes a natural thickener.

[0016] In some embodiments, the second component further includes a second solvent, wherein the second solvent comprises 5-7% by mass in the second component.

[0017] In some embodiments, the first fly ash and the second fly ash are the same, and the first clay is the same as the second clay.

[0018] In some embodiments, both the first straw and the second straw are wheat straw.

[0019] In some embodiments, the first straw is the first straw that has undergone a first anti-degradation treatment.

[0020] In some embodiments, the second straw is a second straw that has undergone a second anti-degradation treatment.

[0021] In some embodiments, the first component consists of the first fly ash, the first clay, the first straw, and the first solvent.

[0022] In other embodiments, the first component consists of the first fly ash, the first clay, the first straw, the first solvent, and the thickener.

[0023] In some embodiments, the thickener is bentonite, and the mass percentage of the thickener in the first component is 3-8%.

[0024] In some embodiments, the second component consists of the second fly ash, the second clay, the second straw, and the second solvent.

[0025] In some embodiments, both the first solvent and the second solvent are water.

[0026] In some embodiments, the first anti-degradation treatment includes: The first straw is crushed to the first target particle size to obtain the first crushed straw; The first crushed straw is soaked in a first silane coupling agent solution to obtain the first soaked straw. After the first soaking, the first straw is drained and then transferred to the first lignin preservative solution for a second soaking, followed by a second draining.

[0027] In some embodiments, the second anti-degradation treatment includes: The second straw is crushed to the second target particle size to obtain the second crushed straw; The second straw after being crushed is soaked in the second silane coupling agent solution to obtain the second straw after the third soaking. After the second straw has been soaked in the third soaking and drained in the third draining, it is transferred to the second lignin preservative solution for a fourth soaking, followed by a fourth draining.

[0028] In some embodiments, the first target particle size and the second target particle size are each independently 1-5 mm.

[0029] In some embodiments, the concentrations of the first silane coupling agent solution and the second silane coupling agent solution are each independently 1-2 wt%.

[0030] In some embodiments, the soaking time for both the first and third soaking is 0.5-1.5 hours.

[0031] In some embodiments, the concentration of the first lignin preservative solution is 0.6-0.9 wt%.

[0032] In some embodiments, the concentration of the second lignin preservative solution is 0.9-1.2 wt%.

[0033] In some embodiments, the second soaking time and the fourth soaking time are both 1-2 hours.

[0034] In some embodiments, the first anti-degradation treatment process does not include the first soaking process.

[0035] The second aspect of this application discloses a method for preparing a sealing material for air-leaking fissures in underground coal mines, comprising: The first fly ash, the first clay and the first straw are added to the first solvent for a first mixing to obtain the first component; The second fly ash, the second clay, and the second straw are added to the second solvent for a second mixing to obtain the second component.

[0036] In some embodiments, both the first mixing and the second mixing are carried out under stirring conditions, and the stirring speed of the second mixing is greater than that of the first mixing.

[0037] In some embodiments, the first mixture of raw materials also includes a thickener.

[0038] The preparation method of the sealing material for air leakage fissures in underground coal mines described in this application has at least the beneficial effects of the sealing material for air leakage fissures in underground coal mines described in this application.

[0039] The third aspect of this application proposes a method for sealing air-leaking fissures in underground coal mines, which involves using the sealing material for sealing air-leaking fissures in underground coal mines described in the first aspect of this application or the sealing material for sealing air-leaking fissures in underground coal mines prepared by the preparation method for sealing air-leaking fissures in underground coal mines described in the second aspect of this application to seal the air-leaking fissures.

[0040] In some embodiments, the method for sealing air-leaking fissures in underground coal mines includes: The first pretreatment is performed on the air-leaking cracks; The first component is used to fill and seal the air leakage cracks after the first pretreatment. The second component is applied to the surface of the air-leaking fissure and its surrounding area after filling and sealing to form a protective layer; The protective layer is then cured.

[0041] In some embodiments, the first pretreatment includes: using an air gun or brush to remove loose coal and dust from the air leakage cracks and the surrounding 100-300mm area.

[0042] In some embodiments, the first pretreatment further includes: for air leakage cracks with a width greater than 1 mm, chiseling a V-shaped groove along the direction of the air leakage crack; and / or, for air leakage cracks with water seepage, temporarily sealing them with cotton wool.

[0043] In some embodiments, the depth of the V-groove is 35-50 mm, and the maximum width of the V-groove is 50-65 mm.

[0044] In some embodiments, the first component is used to fill and seal the pretreated air leakage cracks, including at least one of the following steps: Step 1 and Step 2. Step 1: For air leakage cracks less than 1 mm wide, repeatedly scrape and apply the first component along the direction of the air leakage crack. After ensuring that the first component has naturally penetrated to the depth of the air leakage crack, apply another layer of the first component coating; and / or, Step 2: For the V-shaped groove in the air leakage crack and the crack below it, repeat the following operation until the entire air leakage crack is sealed: send the first component into the V-shaped groove from the bottom of the V-shaped groove under slow pressurization until the first component escapes from the V-shaped groove, then stop sending the first component and wait for the first component to solidify.

[0045] In some embodiments, the slow pressurization is an increase from 0.1 MPa to 0.3 MPa at a rate of 0.05 MPa every 30 seconds.

[0046] In some embodiments, the method for sealing air-leaking fissures in underground coal mines further includes: Before applying the second component to the surface of the filled and sealed air leak fissure and its surrounding area, a second pretreatment step is performed on the surface of the filled and sealed air leak fissure; the second pretreatment includes at least one of the following steps (A), (B), and (C): Step (A): Remove floating and loose particles from the surface of the air leakage cracks after filling and sealing; Step (B): For the air leakage crack surface after filling and sealing where shrinkage cracks with a width of less than 0.3 mm appear, the first component is used to fill the shrinkage peaks and flatten them; Step (C): Wipe the liquid from the damp area on the surface of the leaking cracks after the filling and sealing process, where local dampness has occurred.

[0047] In some embodiments, the second component is applied to the surface of the sealed air leak and its surrounding area in a transverse layered application.

[0048] In some embodiments, during the process of applying the second component to the surface of the air leak and its surrounding area after filling and sealing, for every (200-300mm) × (200-300mm) area applied, the coated area is pressed to expel surface air bubbles.

[0049] In some embodiments, the thickness of the protective layer is 25-40 mm.

[0050] In some embodiments, the protective layer is maintained by covering the surface of the protective layer with a plastic curing film.

[0051] The method for sealing air-leaking fissures in underground coal mines described in this application can bring at least the following beneficial effects: (1) By controlling the proportion of fly ash and clay, solvent content and mixing parameters in the independently set first and second components, the sealing material can meet the different needs of "filling" the bottom layer and "protecting" the top layer of sealed air leakage cracks in coal mines. (2) Good sealing effect of air leakage cracks. For air leakage cracks in the sealed underground coal mine, a dual pretreatment of "bonding and strengthening with thickeners such as bentonite + straw anti-degradation" and "bottom filling with the first component + top setting of the second component protective layer" are adopted to achieve complete filling of air leakage cracks, effectively blocking the air leakage channel and laying the foundation for subsequent harmful gas blocking.

[0052] (3) Simple operation and convenient construction. No special equipment is required for construction, only conventional tools are needed, and the steps are clear (pretreatment-filling-curing-testing), which is suitable for narrow downhole spaces; in addition, the sealing effect test does not require complicated instruments, only the corresponding gas concentration detector is needed.

[0053] (4) Low cost and environmentally friendly. The resource utilization of fly ash (coal-based solid waste) and wheat straw (agricultural waste) realizes "turning waste into treasure". Combined with readily available clay, the three work together to significantly reduce raw material costs; and fully meet the requirements of green mine construction, simultaneously improving environmental and economic benefits, forming a virtuous cycle of "treating waste with waste".

[0054] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0055] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings. in: Figure 1 This is a schematic diagram of the structure of a sealed, leaky crack in an underground coal mine before it was sealed.

[0056] Figure 2 This is a flowchart illustrating a method for sealing air-leaking fissures in underground coal mines, as an exemplary embodiment of this application.

[0057] Figure 3 This is a schematic diagram of the structure of a V-shaped groove constructed along the air leakage crack in a method for sealing air leakage cracks in underground coal mines, which is an exemplary embodiment of this application.

[0058] Figure 4 for Figure 3 Enlarged view of point A in the middle.

[0059] Figure 5 for Figure 4 Enlarged view of point B in the middle.

[0060] Figure 6 This is a schematic diagram of the structure at the air leakage point after sealing the air leakage crack in an underground coal mine, as illustrated by an exemplary embodiment of this application.

[0061] Figure label: 1-Surrounding rock of the tunnel; 2-Tunnel; 3-Air leakage fissure; 4-Sealed wall; 5-V-groove; 6-Protective layer. Detailed Implementation

[0062] The embodiments of this application are described in detail below, with examples of these embodiments illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0063] In this application, the disclosure of numerical ranges includes all values ​​throughout the range and the disclosure of further subdivisions of the range, including the endpoints and subranges given for these ranges.

[0064] Unless otherwise specified, all raw materials and equipment involved in this application are self-made through commercial means or known methods; and all methods involved are conventional methods unless otherwise specified.

[0065] When the term “and / or” is used in a list containing two or more items, it means that any of the listed items can be used alone or in combination with any one or more of the listed items. For example, the expression “A and / or B” is intended to mean A or B or A and B, that is, A only, B only, or a combination of A and B.

[0066] Materials for sealing air leaks and fissures in underground coal mines The coal mine underground air leakage crack sealing material of this application embodiment includes a first component and a second component that are set independently. The first component comprises first fly ash, first clay, and first straw, and the mass ratio of the first fly ash, first clay, and first straw is (8-12):(8-12):(0.8-1.2). The second component includes second fly ash, second clay and second straw, and the mass ratio of the second fly ash, second clay and second straw is (12-18):(28-42):(0.8-1.2).

[0067] The coal mine underground air-leaking fissure sealing material of this application, by controlling the proportion of fly ash and clay in the independently set first and second components, can meet the different needs of "filling" the bottom layer and "protecting" the top layer of underground air-leaking fissures. At the same time, the resource utilization of fly ash (coal-based solid waste) and straw (agricultural waste) realizes "turning waste into treasure", and combined with readily available clay, the three work synergistically to significantly reduce raw material costs. This coal mine underground air-leaking fissure sealing material fully meets the requirements of green mine construction, simultaneously improving environmental and economic benefits, and forming a virtuous cycle of "treating waste with waste".

[0068] By way of non-limiting example, the mass ratio of the first fly ash, the first clay and the first straw includes, but is not limited to, 8:10:1, 12:10:1, 10:8:1.2, 10:10:0.8, 11:8:1, 9:9:0.9, 11:11:1 or 10:10:1.

[0069] In some embodiments, the mass content of the first fly ash and the first clay in the first component is equal.

[0070] As an optional example, the mass ratio of the first fly ash, the first clay, and the first straw is 10:10:1.

[0071] By way of non-limiting example, the mass ratio of the second fly ash, the second clay, and the second straw includes, but is not limited to, 13:30:1, 16:35:0.9, 15:35:1, 15:28:1.2, 15:40:0.8, or 17:38:1.1, and may be selected as 15:35:1.

[0072] In the embodiments of this application, the second component contains a higher proportion of second clay, thus the second component has stronger binding properties compared to the first component. Simultaneously, compared to the first component, the proportions of fly ash and clay in the second component are significantly increased, resulting in: increased density and compactness; improved molding strength and compressive strength; reduced shrinkage deformation; and enhanced water resistance, corrosion resistance, and aging resistance.

[0073] In some embodiments, the first component further includes a first solvent, wherein the mass percentage of the first solvent in the first component is 7-10%, including but not limited to 8% or 9%, and in this case, the first component is a slurry. In the embodiments of this application, when the first fly ash and the first clay are in equal amounts in the first component, a slightly larger amount of the first solvent is required to improve fluidity and facilitate filling of cracks, but the specific amount of the first solvent depends on the properties of the first fly ash and the first clay.

[0074] In some embodiments, the first solvent is water.

[0075] Since there are fewer horizontally oriented air leakage fissures in the sealed area, in order to prevent the slurry from falling under its own weight, in some cases, a thickener, especially a natural thickener, can be added to the first component to improve the cohesiveness and ensure that it can adhere to the wall of the V-shaped groove (see below) opened along the air leakage fissures and not flow along the vertical plane.

[0076] For example, the thickener includes, but is not limited to, at least one of starches (such as corn starch, modified starch, etc.) and natural mineral thickeners (such as bentonite, etc.).

[0077] As an optional example, the thickener is bentonite, and the mass percentage of the thickener in the first component is 3-8%, such as 4%, 5%, or 6%.

[0078] Therefore, as an optional example, the composition of the first component of this application may be as follows: In some embodiments, when no thickener is present, the first component comprises the first fly ash, the first clay, the first straw, and the first solvent. In other embodiments, when a thickener is present, the first component comprises the first fly ash, the first clay, the first straw, the first solvent, and the thickener.

[0079] In some embodiments, the second component further includes a second solvent, the second solvent comprising 5-7% by mass, including but not limited to 5.5%, 6%, or 6.5%, in which case the second component is a slurry. Compared to the content of the first solvent in the first component, reducing the amount of the second solvent in the second component can prevent the slurry from becoming too thin, ensuring plasticity and compaction strength.

[0080] In some embodiments, the second solvent is water.

[0081] As an optional example, the second component consists of the second fly ash, the second clay, the second straw, and the second solvent.

[0082] In some embodiments, the first fly ash and the second fly ash are the same, and the first clay is the same as the second clay.

[0083] In the embodiments of this application, the specific selection of the first fly ash and the second fly ash is not limited, and they can be any fly ash well known in the art, such as at least one of Class F fly ash (derived from anthracite or bituminous coal, with a calcium oxide content ≤10%, referred to as low-calcium fly ash) and Class C fly ash (derived from lignite or sub-bituminous coal, with a calcium oxide content >10%, referred to as high-calcium fly ash). Similarly, the specific selection of the first clay and the second clay is not limited, and they can be any clay well known in the art, such as at least one of kaolin, bentonite, and activated clay.

[0084] As an alternative example, both the first fly ash and the second fly ash are Class F fly ash (low-calcium fly ash), and both the first clay and the second clay are kaolinite.

[0085] As an optional example, the first straw is a first straw that has undergone a first anti-degradation treatment.

[0086] In some embodiments, the first anti-degradation treatment includes the following steps: (1) The first straw is crushed to the first target particle size to obtain the first crushed straw; (2) The first crushed straw is soaked in the first silane coupling agent solution to obtain the first soaked straw; (3) After the first soaking, the first straw is first drained and then transferred to the first lignin preservative solution for a second soaking, followed by a second draining.

[0087] It should be noted that the first soaking process in the first anti-degradation treatment process described above can also be omitted. In this case, the first anti-degradation treatment includes the following steps: 1) The first straw is crushed to the first target particle size to obtain the first crushed straw; 2) The first crushed straw is transferred into the first lignin preservative solution for a second soaking, and then drained.

[0088] As an alternative example, the second straw is a second straw that has undergone a second anti-degradation treatment.

[0089] In some embodiments, the second anti-degradation treatment includes the following steps: (a) The second straw is crushed to the second target particle size to obtain the second crushed straw; (b) The second straw after being crushed is soaked in the second silane coupling agent solution for a third time to obtain the second straw after the third soaking; (c) The second straw after the third soaking is drained in the third time and then transferred to the second lignin preservative solution for a fourth soaking, followed by a fourth draining.

[0090] In some embodiments, the first target particle size and the second target particle size are each independently 1-5 mm, including but not limited to 2 mm, 3 mm or 4 mm.

[0091] It should be noted that in some cases, the first straw with the first target particle size and the second straw with the second target particle size generally need to be obtained by crushing the first straw and the second straw before screening.

[0092] In some embodiments, the concentrations of the first silane coupling agent solution and the second silane coupling agent solution are each independently 1-2 wt%, for example 1.5 wt%.

[0093] It should be noted that, in the embodiments of this application, the composition and preparation method of the first silane coupling agent solution and the second silane coupling agent solution are not limited and can be any silane coupling agent solution well known in the art. The first silane coupling agent solution and the second silane coupling agent solution can be the same or different.

[0094] For example, the silane coupling agents in the first and second silane coupling agent solutions include, but are not limited to, KH. 560 (epoxy) silanes, aminosilanes (such as KH550 / γ-aminopropyltriethoxysilane), sulfur-containing hydrocarbon silanes (such as mercaptopropyltrimethoxysilane), etc.

[0095] For example, the solvents in the silane coupling agents in the first silane coupling agent solution and the second silane coupling agent solution include, but are not limited to, at least one of water, alcohol solvents (e.g., anhydrous ethanol, isopropanol, etc.).

[0096] In some embodiments, the soaking time for the first soaking and the third soaking is 0.5-1.5 hours, for example, 1 hour.

[0097] In some embodiments, the concentration of the first lignin preservative solution is 0.6-0.9 wt%, including but not limited to 0.7 wt% or 0.8 wt%.

[0098] In some embodiments, the concentration of the second lignin preservative solution is 0.9-1.2 wt%, including but not limited to 1 wt% or 1.1 wt%.

[0099] In some embodiments, both the first lignin preservative solution and the second lignin preservative solution consist of a lignin preservative and a solvent. The solvent includes, but is not limited to, water, etc., and the lignin preservative includes, but is not limited to, at least one of lignin quaternary ammonium salts (such as lignin quaternary ammonium salts with model numbers RP-001 / RP-003, etc.) and lignin sulfonates, etc.

[0100] In the embodiments of this application, the lignin preservatives in the first lignin preservative solution and the second lignin preservative solution may be the same or different.

[0101] In some embodiments, the soaking time for the second and fourth soaking is 1-2 hours, for example, 1.5 hours.

[0102] In some implementations, the standard for the first, second, third, and fourth draining is that there is no liquid accumulation or dripping water on the surface of the straw.

[0103] In the embodiments of this application, there are no restrictions on the specific materials of the first straw and the second straw. They can be any straw known in the art, but they are all preferably wheat straw.

[0104] As an optional example, the first straw is wheat straw that has undergone a first anti-degradation treatment, and the second straw is wheat straw that has undergone a second anti-degradation treatment.

[0105] <Preparation Method of Sealing Materials for Air Leakage and Fracturing in Underground Coal Mines> The method for preparing the sealing material for air-leaking fissures in underground coal mines according to the embodiments of this application can be used to prepare the sealing material for air-leaking fissures in underground coal mines according to the embodiments of this application. The method includes the following steps: S1. The first fly ash, the first clay and the first straw are added to the first solvent for a first mixing to obtain the first component; S2 adds the second fly ash, the second clay, and the second straw to the second solvent for a second mixing to obtain the second component.

[0106] In some embodiments, both the first mixing and the second mixing are carried out under stirring conditions.

[0107] In some embodiments, the first mixing is carried out until the slurry is in a state where it "can be formed into a ball when squeezed by hand and can be easily dispersed when pinched", ensuring that the slurry can pass smoothly through the pump pipe during grouting and that no fiber agglomeration or matrix delamination occurs during application.

[0108] In some implementations, the second mixing is carried out until the slurry reaches the standard of "not dripping when applied and able to be quickly formed after compaction", in order to avoid shrinkage and cracking in the later stage.

[0109] In some embodiments, the stirring speed of the second mixture is greater than the stirring speed of the first mixture.

[0110] For example, the first mixing is low-speed stirring, with a stirring speed of 60-90 r / min (e.g., 70 r / min or 80 r / min, etc.) and a stirring time of 10-12 min.

[0111] For example, the second mixing is carried out at a medium speed of 150-200 r / min (e.g., 165 r / min or 180 r / min, etc.) for 10-14 min. Clay is prone to clumping, and the second component has a higher clay content than the first component, so extending the mixing time by 2-3 minutes can ensure uniform mixing.

[0112] Optionally, both the first and second mixtures are mixed using a horizontal mixer.

[0113] In some embodiments, the first mixture of raw materials also includes a thickener. As mentioned earlier, since there are fewer horizontally oriented air gaps in the sealed container, in order to prevent the slurry from falling under its own weight, adding a thickener such as a natural thickener to the slurry can improve the cohesiveness and ensure that the first component can adhere to the V-shaped groove wall and not flow along the vertical plane.

[0114] <Methods for sealing air-leaking fissures in underground coal mines> The following describes a method for sealing air-leaking fissures in underground coal mines, based on an embodiment of this application, with reference to the accompanying drawings.

[0115] Figure 2 This is a flowchart illustrating a method for sealing air-leaking fissures in underground coal mines, as an exemplary embodiment of this application.

[0116] like Figure 2 As shown, the method for sealing air-leaking fissures in underground coal mines uses either the sealing material for sealing air-leaking fissures in underground coal mines according to the embodiments of this application or the sealing material for sealing air-leaking fissures in underground coal mines prepared by the preparation method of the sealing air-leaking fissures in underground coal mines according to the embodiments of this application to seal the air-leaking fissures.

[0117] In some embodiments, the method for sealing air-leaking fissures in underground coal mines includes the following steps: S101. Perform the first pretreatment on the air leakage cracks.

[0118] In some embodiments, the sealing method for air-leaking fissures in underground coal mines involves air-leaking fissures that are... Figure 1 The air leakage fissure 3 is shown. This air leakage fissure 3 exists on the sealed wall 4 inside the tunnel 2, which is located on the surrounding rock 1 of the tunnel.

[0119] In some implementations, the first preprocessing includes the following steps: (i) Use an air gun or brush to remove loose coal and dust from the air-leaking crack 3 and the surrounding 100-300mm area; (ii) For air leakage cracks 3 with a width greater than 1 mm, a V-shaped groove 5 is chiseled along the direction of the air leakage crack 3 (e.g., Figure 3-5 (as shown) (iii) For the leaky crack 3 with water seepage, use cotton wool for temporary sealing, and carry out construction after there is no obvious water accumulation on the surface.

[0120] It should be noted that in the embodiments of this application, during the first pretreatment of the air leakage cracks, step (i) is performed on all air leakage cracks, including air leakage cracks with a width greater than 1 mm, air leakage cracks with a width less than 1 mm, and air leakage cracks with water seepage, etc., and therefore it is necessary. Step (ii) is only performed on air leakage cracks with a width greater than 1 mm, and step (iii) is only performed on air leakage cracks with water seepage. Therefore, step (i) is the first step of the first pretreatment and is also a necessary step, while steps (ii) and (iii) are selective steps, which are performed only when there are corresponding air leakage cracks with a width greater than 1 mm and air leakage cracks with water seepage, and are not performed if there are none; if both air leakage cracks with a width greater than 1 mm and air leakage cracks with water seepage exist, the order of steps (ii) and (iii) is not restricted.

[0121] In some implementations, in step (ii), a V-groove 5 is excavated along the direction of the salt leakage fissure 3 using a pneumatic pick.

[0122] In the embodiments of this application, such as Figure 5 As shown, the V-groove 5 has its open side facing the top ( Figure 1 In the three-dimensional x, y, z coordinate system, the negative x-axis direction and the tip pointing towards the bottom are indicated by... Figure 1 A V-groove in the positive x-axis direction of the three-dimensional coordinate system of x, y, z.

[0123] In some embodiments, the depth of the V-groove is 35-50 mm, and the maximum width of the V-groove is 50-65 mm. Here, the maximum width refers to the maximum width on the open side of the V-groove 5 (the width of the V-groove 5 at its furthest point in the negative x-axis direction). Since the bottom slurry has good fluidity, the size of the groove can be appropriately reduced.

[0124] For example, the depth of the V-groove is not limited to 40mm or 45mm, and the maximum width of the V-groove is not limited to 55mm or 65mm.

[0125] S102. The first component is used to fill and seal the air leakage cracks after the first pretreatment in step S101.

[0126] In some embodiments, the first component is used to fill and seal the pretreated air leakage cracks, including at least one of the following steps: Step 1 and Step 2. Step 1: For air leakage cracks 3 with a width of less than 1mm (this type of air leakage crack can also be called a micro crack), scrape the first component back and forth along the direction of the air leakage crack. After ensuring that the first component naturally penetrates into the depth of the air leakage crack, apply another layer of the first component coating. Step 2: For the V-shaped groove in the air leakage crack and the crack below it, repeat the following operation until the entire air leakage crack is sealed: send the first component into the V-shaped groove from the bottom of the V-shaped groove under slow pressurization until the first component escapes from the V-shaped groove, then stop sending the first component and wait for the first component to solidify.

[0127] It is understandable that step S101 involves "carving a V-shaped groove 5 along the direction of the air leakage crack 3 with a width greater than 1 mm", which means that the second process corresponds to the air leakage crack 3 with a width greater than 1 mm. Step S102 uses the first component to fill and seal the air leakage crack after the first pretreatment in step S101, which is to fill and seal the air leakage crack 3 separately according to its different width.

[0128] In some embodiments, in step one above, the first component is applied repeatedly with a regular trowel along the direction of the air-leaking crack.

[0129] In some embodiments, the method to ensure that the first component naturally penetrates to the depth of the air leakage crack in step one above is to pause for 2 seconds after every 150mm of coating, allowing the slurry to naturally penetrate to the depth of the air leakage crack.

[0130] In some embodiments, in step one above, the total thickness of the first component coating applied is 3-5 mm, for example, 4 mm. In the embodiments of this application, the purpose of applying the first component coating in step one above is to ensure that there are no voids remaining.

[0131] In some embodiments, in step two above, the slow pressurization is to increase the pressure from 0.1 MPa to 0.3 MPa at a rate of 0.05 MPa every 30 seconds.

[0132] In some embodiments, the method of feeding the material into the V-groove from the bottom of the V-groove in step two above includes: The second component is poured into a grout container, which is connected to a grouting pump via a suction pipe. The end of the suction pipe furthest from the pump is connected to a grouting nozzle, which is positioned flush against the bottom of the V-shaped groove. Grout is injected gradually upwards from the lower end of the crack (along...). Figure 1 Grouting from the positive X-axis direction to the negative X-axis direction.

[0133] In the embodiments of this application, the above-mentioned second-cycle operation can gradually fill the crack upwards until the entire crack is completely sealed.

[0134] S103. The second component is coated onto the surface of the air leakage crack and its surrounding area after being filled and sealed in step S102 to form a protective layer.

[0135] Relative to the surface of the leaking crack after filling and sealing in step S102, the protective layer is located on the top layer of the leaking crack, while the portion of the second component that has filled and cured the crack is located at the bottom layer. The surface of the leaking crack after filling and sealing in step S102 is also the surface of the first component slurry after curing the first component slurry, which forms the bottom layer "filler" after sealing the leaking crack. The protective layer itself is not used to fill the leaking crack; the protective layer is intended to cover and protect the surface of the leaking crack after filling and sealing in step S102 (i.e., the first component used for filling the leaking crack in step S102).

[0136] In some embodiments, the method for sealing air-leaking fissures in underground coal mines further includes a second pretreatment step on the surface of the sealed air-leaking fissures and its surrounding area before applying the second component. The purpose of the second pretreatment is to remove impurities to avoid damaging the bottom layer formed by the first component (i.e., the surface of the sealed air-leaking fissures), ensure the surface (i.e., the surface of the sealed air-leaking fissures) is smooth, and remove water stains to prevent the top layer of the second component slurry from stratifying due to humidity differences.

[0137] In some embodiments, the second preprocessing includes at least one of the following steps (A), (B), and (C): Step (A): Remove floating and loose particles from the surface of the air leakage cracks after filling and sealing; Step (B): For the air leakage crack surface after filling and sealing, where there are shrinkage cracks with a width of less than 0.3 mm (also known as micro-shrinkage cracks), the first component is used to fill the shrinkage peaks and flatten them; Step (C): Wipe the liquid from the damp area on the surface of the leaking cracks after the filling and sealing process, where local dampness has occurred.

[0138] In some embodiments, in the above step (A), a wire brush is used to lightly brush the surface of the air leakage crack after filling and sealing to remove floating dust and loose particles (in an effort to avoid damaging the underlying layer).

[0139] In some embodiments, in step (B) above, the surface of the leaking crack after filling and sealing, where a shrinkage crack with a width of less than 0.3 mm appears, is filled with a small amount of the first component and flattened to ensure that the surface is flat and without protrusions.

[0140] In some embodiments, in the above step (C), the surface of the leaking cracks after filling and sealing that has become locally damp is wiped with a dry cloth until there are no obvious water stains, in order to prevent the second component of the top layer slurry from separating due to humidity difference.

[0141] In some implementations, the surrounding area of ​​the air leakage crack refers to the area 200-300mm away from the air leakage crack, such as the area 250mm away from the air leakage crack.

[0142] In some embodiments, applying the second component to the surface of the air-leaking fissure and its surrounding area after filling and sealing in step S102 includes: using a notched trowel to apply the second component to the surface of the air-leaking fissure and its surrounding area after filling and sealing in step S102. The second component has a high clay content, and the notched trowel facilitates thickness control.

[0143] In some embodiments, the second component is applied to the surface of the sealed air leak and its surrounding area in a transverse layered application.

[0144] The horizontal layering method is a conventional technique and will not be elaborated further here.

[0145] In some embodiments, during the process of applying the second component to the surface of the air leak and its surrounding area after filling and sealing, for every (200-300mm) × (200-300mm) area applied, the coated area is pressed to expel surface air bubbles.

[0146] As an alternative example, for every (200-300mm) × (200-300mm) area coated, gently press the coated area once with the back of a trowel to remove surface air bubbles.

[0147] In some embodiments, the thickness of the protective layer is 25-40 mm, including but not limited to 30 mm or 35 mm. It should be noted that the thickness of the protective layer is generally 25-35 mm, and is increased to 40 mm for areas with concentrated cracks.

[0148] S104. Curing the protective layer formed in step S103.

[0149] In some embodiments, the protective layer is maintained by covering the surface of the protective layer with a plastic curing film.

[0150] In some implementations, the curing time is 50-60 hours, including but not limited to 53 hours or 56 hours.

[0151] In some implementations, the method for sealing air-leaking fissures in underground coal mines also includes a step of conducting phased inspections during the curing process.

[0152] Specifically, this stage of inspection includes: after 48 hours of curing, peel off a corner of the plastic curing film for inspection. If there are no cracks on the surface of the slurry and no marks when pressed, the central area can be left covered.

[0153] In some embodiments, the method for sealing air-leaking fissures in underground coal mines further includes: After the curing is completed, remove the plastic curing film and observe the surface of the protective layer. If there is no dampness or hollowness, the top layer is deemed qualified (i.e., the protective layer curing is qualified).

[0154] In the embodiments of this application, the plastic curing film is a transparent plastic film commonly used in engineering, specifically used to cover concrete, sealing materials, mortar, etc., for moisture retention, heat preservation, and wind protection curing.

[0155] For example, the aforementioned plastic protective film includes, but is not limited to, polyethylene film (e.g., polyethylene film with a thickness of 0.08-0.2 mm) and polyvinyl chloride film (e.g., polyvinyl chloride film with a thickness of 0.10-0.15 mm).

[0156] In some embodiments, the method for sealing air-leaking fissures in underground coal mines also includes a step of testing the sealing effect after all the above steps.

[0157] In some implementations, the above-mentioned sealing effect detection includes: using a corresponding gas detection device (such as a gas detector) outside the sealed wall after sealing to detect the methane gas concentration near the air leakage crack, comparing the detected methane gas concentration with the methane gas concentration in the roadway or working space, and judging the sealing effect based on the magnitude of the detected methane gas concentration and the methane gas concentration in the roadway or working space.

[0158] The specific method for judging the effectiveness of the blockade is as follows: If the methane gas concentration near the external air leakage cracks in the sealed wall is equal to the methane gas concentration inside the tunnel or work area, it indicates that the methane gas leakage within the sealed space is minimal, and the sealing effect is good. If the methane gas concentration near the external air leakage cracks in the sealed wall is greater than the methane gas concentration inside the tunnel or work area, it indicates that the methane gas leakage within the sealed space is significant, and the sealing effect is poor (i.e., bad). If no methane gas is detected near the external air leakage cracks in the sealed wall or inside the tunnel or work area, it indicates that there is absolutely no methane gas leakage within the sealed space, and the sealing effect is excellent. Structures with good and excellent sealing effects are as follows: Figure 6 As shown ( Figure 6 The middle protective layer 6 is located on the surface of the air leakage crack 3 and covers the air leakage crack 3 and its surrounding area. The air leakage crack 3 is the air leakage crack after being filled and sealed in step S102.

[0159] It should be noted that in this application, "tunnel" refers to the tunnel outside the sealed wall, which is located outside the sealed wall along with the area near the air leakage crack. Both are in the same space, so comparing their concentrations can determine whether the sealed wall is leaking. For example, if the sealed wall is not leaking, the area near the air leakage crack and the tunnel outside the sealed wall are in the same space, and there should be no difference in concentration. If the sealed wall is leaking, the leaked methane will first accumulate near the air leakage crack, causing the methane concentration in that area to be higher than that in the tunnel outside the sealed wall.

[0160] Furthermore, it should be noted that in some cases, the sealing material for sealing air-leaking fissures in underground coal mines involved in the sealing method of this application requires on-site preparation. Therefore, the preparation method of the sealing material for sealing air-leaking fissures in underground coal mines in this application can also be considered as part of the sealing method for sealing air-leaking fissures in underground coal mines. The sealing material can be prepared before the first pretreatment of the air-leaking fissures in step S101 (e.g., ...). Figure 2 (As shown).

[0161] In summary, the sealing method for air-leaking fissures in underground coal mines according to the embodiments of this application adopts a dual pretreatment of "bonding reinforcement + straw anti-degradation". The core difference lies in controlling the proportion of fly ash and clay in the first and second components of the sealing material for air-leaking fissures in underground coal mines, the amount of water added (i.e., the amount of the first and second solvents), and the stirring parameters. This adapts to the different needs of the bottom layer "filling" and the top layer "protection", thereby ensuring the complete filling of the air-leaking fissures, effectively blocking the air leakage channels, and laying the foundation for subsequent harmful gas blocking.

[0162] The following non-limiting embodiments further illustrate certain features of the present technology.

[0163] The following embodiments and comparative examples all involve structures before sealing air-leaking fissures in underground coal mines. Figure 1 The structure shown, and the preparation method of the sealing material for air-leaking fissures in coal mines in each embodiment and comparative examples 1-3, after completion, the structure of the air-leaking fissures is as follows: Figure 6 As shown.

[0164] Example 1 [Materials for sealing air leaks and fissures in underground coal mines] The sealing material for air-leaking fissures in underground coal mines in this embodiment consists of two independently configured components: a first component and a second component. Wherein: The first component consists of first fly ash, first clay, first degraded wheat straw and water; the water content in the first component is 8.5% by mass, and the mass ratio of the first fly ash, first clay and first degraded wheat straw is 10:10:1; the first fly ash is F-type fly ash (low-calcium ash, calcium content is 5wt%), and the first clay is kaolinite.

[0165] The preparation method of the first degraded wheat straw is as follows: the wheat straw is crushed to a particle size range of 1-5 mm, then soaked in a 1.5 wt% first silane coupling agent solution for 1 hour, drained, and then soaked in a 0.75 wt% first lignin preservative solution for 1.5 hours. Finally, it is drained until there is no liquid accumulation or dripping on the surface, thus obtaining the first degraded wheat straw. The 1.5 wt% first silane coupling agent solution was purchased from Jiangxi Chenguang New Material Co., Ltd., and the silane coupling agent was KH-560 (γ-glycidyl ether oxypropyltrimethoxysilane); the 0.75 wt% first lignin preservative solution was purchased from Wuhan Xingzhongcheng Technology Co., Ltd., and the lignin preservative was ACQ (alkylammonium copper).

[0166] The second component consists of second fly ash, second clay, second degraded wheat straw, and water; the water content in the second component is 6% by mass, and the mass ratio of the second fly ash, second clay, and second degraded wheat straw is 15:35:1; the second fly ash is Class F fly ash (low-calcium ash, calcium content is 5wt%), and the second clay is kaolinite.

[0167] The preparation method of the second-degraded wheat straw is as follows: The wheat straw is crushed to a particle size range of 1-5 mm, then soaked in a 1.5 wt% second silane coupling agent solution for 1 hour. After draining, it is transferred to a 1.05 wt% second lignin preservative solution for 1.5 hours. Finally, it is drained until there is no liquid accumulation or dripping on the surface, thus obtaining the second-degraded wheat straw. The 1.5 wt% second silane coupling agent solution was purchased from Jiangxi Chenguang New Material Co., Ltd., and the silane coupling agent was KH-560 (γ-glycidyl ether oxypropyltrimethoxysilane). The 1.05 wt% second lignin preservative solution was purchased from Wuhan Xingzhongcheng Technology Co., Ltd., and the lignin preservative was ACQ (alkylammonium copper).

[0168] [Preparation Method of Sealing Material for Air Leakage and Fracturing in Underground Coal Mines] The preparation method of the sealing material for air-leaking fissures in underground coal mines in this embodiment includes the following steps: (1) Preparation of the first component: The first fly ash, the first clay, the first degraded straw and water in the formula amount are stirred at a low speed of 70r / min for 11 minutes in a horizontal mixer to obtain the first component.

[0169] (2) Preparation of the second component: The second fly ash, the second clay, the second degraded wheat straw and water in the formula amount are stirred at a medium speed of 160r / min for 13 minutes in a horizontal mixer to obtain the second component.

[0170] Methods for sealing air-leaking fissures in underground coal mines The method for sealing air-leaking fissures in underground coal mines according to this embodiment includes the following steps: S1. Pre-treatment of air leakage cracks. Use an air gun to remove loose coal and dust from the air leakage cracks and the surrounding 200mm area; for cracks wider than 1mm, use a pneumatic pick to chisel a V-shaped groove (groove depth 42mm, groove width 58mm) along the direction; if water seepage cracks are encountered, temporarily seal them with cotton wool, and proceed with construction after there is no obvious water accumulation on the surface.

[0171] S2. Filling and sealing air leakage cracks.

[0172] 1) Micro cracks (width ≤ 1mm): Use a regular trowel to take the first component and "scrape back and forth" along the crack direction. Pause for 2 seconds every 150mm of scraping to allow the paste to naturally penetrate into the depth of the crack. Then apply another layer (total thickness 4mm) to ensure no voids remain.

[0173] 2) V-shaped groove and the fissure below it (width > 1mm): Insert the grouting pump suction pipe into the grout container containing the first component, and press the grouting nozzle against the bottom of the groove (grouting from the bottom of the fissure upwards). Slowly increase the pressure (from 0.1MPa to 0.3MPa, increasing by 0.05MPa every 30 seconds). Whenever the first component of grout overflows from the fissure, stop grouting and wait for the grout to solidify. Repeat this process to gradually fill the fissure upwards until the entire fissure is sealed.

[0174] S3. Construction of protective layer.

[0175] 1) Pretreatment of the surface of the air leakage crack after filling and sealing in step S2: Lightly brush the surface of the air leakage crack after filling and sealing in step S2 with a wire brush to remove dust and loose particles. Then, perform the following operations on the surface of the air leakage crack after filling and sealing in step S2 to remove dust and loose particles: For any small shrinkage cracks (width ≤ 0.3 mm), fill and flatten them with a small amount of the first component slurry (the amount should be enough to completely fill and flatten the cracks where small shrinkage cracks appear), ensuring that the surface is flat and without protrusions; if the surface is locally damp, wipe it with a dry cloth until there are no obvious water stains.

[0176] 2) Use a notched trowel to take the second component of the slurry and apply it in a horizontal layer along the surface of the air-leaking cracks after the pretreatment in step S2 and the surrounding 250mm area. The overall thickness of the slurry should be controlled at 30mm (to 40mm in areas with concentrated cracks). For each 250mm×250mm area, press lightly once with the back of the trowel to remove surface air bubbles and form a protective layer.

[0177] S4. Sealing Material Curing. Cover the surface of the protective layer formed in step S3 away from the air leakage crack with a plastic curing film (1mm thick polyethylene film) and cure for 55 hours. During this period, after 48 hours of curing, peel off a corner of the film for inspection: if there are no cracks on the surface of the protective layer and no marks when pressed, the central area can be left covered; after the curing is completed, remove the film and observe that the surface of the protective layer is free of moisture and hollow areas, and the curing of the protective layer is deemed qualified.

[0178] Example 2 This embodiment is basically the same as Embodiment 1, with the following differences: In coal mine underground sealing materials for air leakage cracks: The preparation method of the first degraded wheat straw is as follows: the wheat straw is crushed to a particle size range of 1-5 mm, then soaked in a 0.75 wt% first lignin preservative solution for 1.5 h, and finally drained until there is no liquid accumulation or dripping on the surface, thus obtaining the first degraded wheat straw. Specifically: the 1.5 wt% first silane coupling agent solution was purchased from Jiangxi Chenguang New Material Co., Ltd., and the silane coupling agent was KH-560 (γ-glycidyl ether oxypropyltrimethoxysilane). The 0.75 wt% first lignin preservative solution was purchased from Wuhan Xingzhongcheng Technology Co., Ltd., and the lignin preservative was ACQ (alkylammonium copper).

[0179] Example 3 This embodiment is basically the same as Embodiment 1, with the following differences: In coal mine underground sealing materials for air leakage cracks: The first component consists of first fly ash, first clay, first degraded wheat straw, water and thickener; the water content in the first component is 8.5% by mass, and the thickener is bentonite, with a thickener content of 5.5% by mass in the first component.

[0180] In the preparation method of sealing materials for air-leaking fissures in underground coal mines: Step (1) is as follows: The first fly ash, the first clay, the first degraded wheat straw, water and thickener in the formula amount are mixed at a low speed of 80r / min for 11 minutes using a horizontal mixer to obtain the first component.

[0181] Example 4 This embodiment is basically the same as Embodiment 1, with the following differences: In coal mine underground sealing materials for air leakage cracks: The water content in the first component is 7% by mass, and the water content in the second component is 7% by mass.

[0182] In the preparation method of sealing materials for air-leaking fissures in underground coal mines: In step (1), stir at a low speed of 60 r / min for 12 minutes; In step (2), stir at a medium speed of 175 r / min for 12 minutes.

[0183] Example 5 This embodiment is basically the same as Embodiment 1, with the following differences: In coal mine underground sealing materials for air leakage cracks: The first component contains 10% water by mass, and the second component contains 5% water by mass.

[0184] In the preparation method of sealing materials for air-leaking fissures in underground coal mines: In step (1), stir at a low speed of 90 r / min for 10 minutes; In step (2), stir at a medium speed of 150 r / min for 14 minutes.

[0185] Example 6 This embodiment is basically the same as Embodiment 1, with the following differences: In coal mine underground sealing materials for air leakage cracks: The preparation method of the first degraded wheat straw is as follows: The wheat straw is crushed to a particle size range of 1-5 mm, then soaked in a 1 wt% first silane coupling agent solution for 1 hour. After draining, it is transferred to a 0.9 wt% first lignin preservative solution for 1.5 hours, and finally drained until there is no liquid accumulation or dripping on the surface, thus obtaining the first degraded wheat straw. The 1 wt% first silane coupling agent solution was purchased from Jiangxi Chenguang New Material Co., Ltd., and the silane coupling agent is KH-560 (γ-glycidyl ether oxypropyltrimethoxysilane). The 0.9 wt% first lignin preservative solution was purchased from Wuhan Xingzhongcheng Technology Co., Ltd., and the lignin preservative is ACQ (alkylammonium copper).

[0186] The preparation method of the second-degraded wheat straw is as follows: The wheat straw is crushed to a particle size range of 1-5 mm, then soaked in a 2 wt% second silane coupling agent solution for 1 hour. After draining, it is transferred to a 0.9 wt% second lignin preservative solution and soaked for 1.5 hours. Finally, it is drained until there is no liquid accumulation or dripping on the surface, thus obtaining the second-degraded wheat straw. The 2 wt% second silane coupling agent solution was purchased from Jiangxi Chenguang New Material Co., Ltd., and the silane coupling agent was KH-560 (γ-glycidyl ether oxypropyltrimethoxysilane). The 0.9 wt% second lignin preservative solution was purchased from Wuhan Xingzhongcheng Technology Co., Ltd., and the lignin preservative was ACQ (alkylammonium copper).

[0187] Example 7 This embodiment is basically the same as Embodiment 1, with the following differences: In coal mine underground sealing materials for air leakage cracks: The preparation method of the first degraded wheat straw is as follows: The wheat straw is crushed to a particle size range of 1-5 mm, then soaked in a 2 wt% first silane coupling agent solution for 1 hour. After draining, it is transferred to a 0.6 wt% first lignin preservative solution for 1.5 hours, and finally drained until there is no liquid accumulation or dripping on the surface, thus obtaining the first degraded wheat straw. The 2 wt% first silane coupling agent solution was purchased from Jiangxi Chenguang New Material Co., Ltd., and the silane coupling agent was KH-560 (γ-glycidyl ether oxypropyltrimethoxysilane). The 0.6 wt% first lignin preservative solution was purchased from Wuhan Xingzhongcheng Technology Co., Ltd., and the lignin preservative was ACQ (alkylammonium copper).

[0188] The preparation method of the second-degraded wheat straw is as follows: The wheat straw is crushed to a particle size range of 1-5 mm, then soaked in a 1 wt% second silane coupling agent solution for 1 hour. After draining, it is transferred to a 1.2 wt% second lignin preservative solution and soaked for 1.5 hours. Finally, it is drained until there is no liquid accumulation or dripping on the surface, thus obtaining the second-degraded wheat straw. The 1 wt% second silane coupling agent solution was purchased from Jiangxi Chenguang New Material Co., Ltd., and the silane coupling agent was KH-560 (γ-glycidyl ether oxypropyltrimethoxysilane). The 1.2 wt% second lignin preservative solution was purchased from Wuhan Xingzhongcheng Technology Co., Ltd., and the lignin preservative was ACQ (alkylammonium copper).

[0189] Example 8 This embodiment is basically the same as Embodiment 1, with the following differences: In coal mine underground sealing materials for air leakage cracks: In the first component, the mass ratio of the first fly ash, the first clay, and the first degraded wheat straw is 8:8:1.2; In the second component, the mass ratio of the second fly ash, the second clay, and the second degraded wheat straw is 18:42:0.8.

[0190] Example 9 This embodiment is basically the same as Embodiment 1, with the following differences: In coal mine underground sealing materials for air leakage cracks: In the first component, the mass ratio of the first fly ash, the first clay, and the first degraded wheat straw is 12:8:0.8; In the second component, the mass ratio of the second fly ash, the second clay, and the second degraded wheat straw is 18:28:1.2.

[0191] Comparative Example 1 This comparative example uses cement and gypsum to seal all the air-leaking cracks in Example 1.

[0192] Comparative Example 2 This comparative example uses only kaolinite from clay to seal all the air-leaking cracks in Example 1.

[0193] Comparative Example 3 This comparative example only uses plaster to seal all the air-leaking cracks in Example 1.

[0194] Comparative Example 4 This comparative example only uses cement to seal all the air-leaking cracks in Example 1.

[0195] II. Effect Test The sealing effect of the sealing method for air leakage fissures in underground coal mines in each embodiment and comparative example was tested. The testing method was as follows: After sealing, a gas detector is used outside the sealed wall to detect the methane gas concentration near the leaking crack. The sealing effect is judged by comparing the concentration with that in the tunnel outside the sealed wall. The area near the leaking crack refers to the entire detection space consisting of the detection area multiplied by the detection height. The detection area is the area 50% larger than the filled area, and the detection height is 500mm.

[0196] The specific method for judging the effectiveness of the blockade is as follows: If the methane gas concentration near the air leakage crack outside the sealed wall is equal to the methane gas concentration inside the roadway, it indicates that the methane gas leakage from the space enclosed by the sealed wall is relatively small, and the sealing effect is good. If the methane gas concentration near the air leakage crack outside the sealed wall is greater than the methane gas concentration inside the roadway, it indicates that the methane gas leakage from the space enclosed by the sealed wall is relatively large, and the sealing effect is poor (i.e., bad). If no methane gas can be detected near the air leakage crack outside the sealed wall or inside the roadway, it indicates that there is absolutely no methane gas leakage from the space enclosed by the sealed wall, and the sealing effect is very good.

[0197] The results of the sealing effect test are shown in Table 1.

[0198] Table 1. Test results of sealing effect

[0199] As can be seen from Table 1, the sealing effect of the coal mine underground air leakage crack sealing material of this application and the sealing method of this application for sealing coal mine underground air leakage cracks is significantly better than that of the comparative example.

[0200] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A sealing material for air-leaking cracks in underground coal mines, characterized in that, Includes a first component and a second component that are set up independently; The first component comprises first fly ash, first clay, and first straw, and the mass ratio of the first fly ash, first clay, and first straw is (8-12):(8-12):(0.8-1.2). The second component includes second fly ash, second clay and second straw, and the mass ratio of the second fly ash, second clay and second straw is (12-18):(28-42):(0.8-1.2).

2. The sealing material for air-leaking cracks in underground coal mines according to claim 1, characterized in that, In the first component, the mass content of the first fly ash and the first clay are equal; And / or, the mass ratio of the first fly ash, the first clay and the first straw is 10:10:1; And / or, the mass ratio of the second fly ash, the second clay, and the second straw is 15:35:

1.

3. The sealing material for air-leaking cracks in underground coal mines according to claim 1 or 2, characterized in that, The first component further includes a first solvent, wherein the first solvent comprises 7-10% by mass in the first component; And / or, the first component further includes a thickener, said thickener including natural thickeners; And / or, the second component further includes a second solvent, wherein the second solvent comprises 5-7% by mass in the second component; And / or, the first fly ash and the second fly ash are the same, and the first clay is the same as the second clay; And / or, both the first straw and the second straw are wheat straw; And / or, the first straw is the first straw that has undergone the first anti-degradation treatment; And / or, the second straw is a second straw that has undergone a second anti-degradation treatment.

4. The sealing material for air-leaking cracks in underground coal mines according to claim 3, characterized in that, The first component is composed of the first fly ash, the first clay, the first straw, and the first solvent, or the first component is composed of the first fly ash, the first clay, the first straw, the first solvent, and the thickener; And / or, the thickener is bentonite, and the mass percentage of the thickener in the first component is 3-8%; And / or, the second component is composed of the second fly ash, the second clay, the second straw, and the second solvent; And / or, both the first solvent and the second solvent are water; And / or, the first anti-degradation treatment includes: The first straw is crushed to the first target particle size to obtain the first crushed straw; The first crushed straw is soaked in a first silane coupling agent solution to obtain the first soaked straw. After the first soaking, the first straw is first drained and then transferred to the first lignin preservative solution for a second soaking, followed by a second draining. And / or, the second anti-degradation treatment includes: The second straw is crushed to the second target particle size to obtain the second crushed straw; The second straw after being crushed is soaked in the second silane coupling agent solution to obtain the second straw after the third soaking. After the second straw has been soaked in the third soaking and drained in the third draining, it is transferred to the second lignin preservative solution for a fourth soaking, followed by a fourth draining.

5. The sealing material for air-leaking cracks in underground coal mines according to claim 4, characterized in that, The first target particle size and the second target particle size are each independently 1-5 mm; And / or, the concentrations of the first silane coupling agent solution and the second silane coupling agent solution are each independently 1-2 wt%; And / or, the soaking time for both the first and third soaking is 0.5-1.5 hours; And / or, the concentration of the first lignin preservative solution is 0.6-0.9 wt%; And / or, the concentration of the second lignin preservative solution is 0.9-1.2 wt%; And / or, the soaking time for both the second and fourth soaking is 1-2 hours; And / or, the first anti-degradation treatment process does not include the first soaking process.

6. A method for preparing a sealing material for air-leaking fissures in underground coal mines as described in any one of claims 1 to 5, characterized in that, include: The first fly ash, the first clay and the first straw are added to the first solvent for a first mixing to obtain the first component; The second fly ash, the second clay, and the second straw are added to the second solvent for a second mixing to obtain the second component; Preferably, both the first mixing and the second mixing are carried out under stirring conditions, and the stirring speed of the second mixing is greater than the stirring speed of the first mixing. Preferably, the stirring speed of the first mixture is 60-90 r / min, and the stirring speed of the second mixture is 150-200 r / min; Preferably, the raw materials in the first mixture also include a thickener.

7. A method for sealing air-leaking fissures in underground coal mines, characterized in that, The air leakage fissures are sealed using the coal mine underground air-sealing fissure sealing material as described in any one of claims 1 to 5 or the coal mine underground air-sealing fissure sealing material prepared by the preparation method described in claim 6.

8. The sealing method according to claim 7, characterized in that, The method for sealing air-leaking fissures in underground coal mines includes: The first pretreatment is performed on the air-leaking cracks; The first component is used to fill and seal the air leakage cracks after the first pretreatment. The second component is applied to the surface of the air-leaking fissure and its surrounding area after filling and sealing to form a protective layer; The protective layer is then cured; Preferably, the first pretreatment includes: using an air gun or brush to remove loose coal and dust from the air leakage cracks and the surrounding 100-300mm range; Preferably, the first preprocessing further includes: For air leakage fissures wider than 1 mm, a V-shaped groove is chiseled along the direction of the air leakage fissure; and / or, For leaky cracks that allow water to seep in, use cotton wool for temporary sealing.

9. The sealing method according to claim 8, characterized in that, The depth of the V-groove is 35-50mm, and the maximum width of the V-groove is 50-65mm. And / or, the pretreated air leakage cracks are filled and sealed using the first component, including at least one of the following steps: Step 1 and Step 2: Step 1: For air leakage cracks with a width of less than 1 mm, scrape the first component back and forth along the direction of the air leakage crack. After ensuring that the first component naturally penetrates into the depth of the air leakage crack, apply another layer of the first component coating. Step 2: For the V-shaped groove in the air-leaking crack and the crack below it, repeat the following operation until the entire air-leaking crack is sealed: feed the first component into the V-shaped groove from the bottom of the V-shaped groove under slow pressurization until the first component escapes from the V-shaped groove, then stop feeding the first component and wait for the first component to solidify. Preferably, the slow pressurization is an increase from 0.1 MPa to 0.3 MPa at a rate of 0.05 MPa every 30 seconds.

10. The sealing method according to claim 8 or 9, characterized in that, The method for sealing air-leaking fissures in underground coal mines also includes: Before applying the second component to the surface of the filled and sealed air leak fissure and its surrounding area, a second pretreatment step is performed on the surface of the filled and sealed air leak fissure; the second pretreatment includes at least one of the following steps (A), (B), and (C): Step (A): Remove floating and loose particles from the surface of the air leakage cracks after filling and sealing; Step (B): For the air leakage crack surface after filling and sealing where shrinkage cracks with a width of less than 0.3 mm appear, the first component is used to fill the shrinkage peaks and flatten them; Step (C): Wipe the liquid from the damp area on the surface of the air leak cracks after the filling and sealing process, where local dampness has occurred. And / or, the method of applying the second component to the surface of the air leak and its surrounding area after filling and sealing includes transverse layering; And / or, during the process of applying the second component to the surface of the air leak crack and its surrounding area after filling and sealing, press the coated area to remove surface air bubbles for every (200-300mm) × (200-300mm) area coated; And / or, the thickness of the protective layer is 25-40 mm; And / or, to maintain the protective layer, including: covering the surface of the protective layer with a plastic curing film for maintenance.

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