Emergency plugging method for gas overrun on surface of coal body

Abstract

The invention relates to a coal body surface gas overrun emergency plugging method in the technical field of coal mine gas overrun treatment. The coal body surface gas overrun emergency plugging method comprises the following steps: selecting a coating, namely selecting the coating which has the porosity of less than 5% and the coating adhesive force of more than 1.5 MPa after being cured in a coating with the thickness of 0.5-1mm, can stably work for more than 12 months at normal temperature, and can resist water and the temperature range of-10 to 60 DEG C; pretreatment: carrying out simple filling treatment on obvious macroscopic fractures on the surface of the coal body; the paint is diluted with water until the viscosity is 200-300 mPas, the paint is poured into a storage tank of spraying equipment after being evenly stirred, and the paint is left to stand for 5 minutes to remove bubbles; and spraying or spraying: spraying by adopting a high-pressure airless spraying machine or spraying by adopting a dust removal spraying machine. According to the method, coal body surface gas over-limit emergency plugging can be rapidly, efficiently and stably achieved in an environment-friendly mode.

Description

Technical Field

[0001] This invention belongs to the field of coal mine gas over-limit control technology, and in particular relates to an emergency sealing method for coal surface gas over-limit. Background Technology

[0002] In coal mining operations, continuous coal mining and coal roadway excavation are crucial for ensuring efficient coal production. However, excessive gas emissions remain a core challenge that restricts production efficiency and threatens operational safety. As a flammable and explosive gas, methane can easily cause serious safety accidents such as methane explosions and asphyxiation when it accumulates on the surface of coal and in the surrounding roadways and exceeds the safe concentration threshold. This can not only cause huge casualties and property losses, but also seriously affect the normal production order of coal mines, leading to production interruptions and project delays, and imposing a heavy economic burden on coal mining enterprises. Currently, various methods have been adopted in the industry to address the problem of excessive methane concentration on the surface of coal seams. For example, increasing ventilation to dilute the methane concentration and using the ventilation system to remove high-concentration methane from the work area can reduce the methane concentration to some extent. However, due to limitations such as roadway layout and ventilation equipment capacity, it is often difficult to quickly and effectively control high-concentration methane that suddenly emerges from the surface of a local coal seam within a safe range, and the energy consumption is also high. Another common approach is to use gas extraction technology, which involves drilling extraction boreholes in the coal seam to extract the gas inside the coal seam in advance, thereby reducing the amount of gas emitted during tunneling. However, extraction technology requires system design and construction in advance, and the emergency response speed is slow in the event of a sudden gas exceedance on the coal seam surface, making it difficult to meet the need for immediate sealing. In addition, some sealing materials are used to seal cracks on the coal surface to reduce gas outbursts. However, existing sealing materials often have problems such as slow curing speed, insufficient bonding strength with the coal surface, and poor adaptability to coal deformation. When the coal body is deformed due to mining, the cracks are prone to reopening, leading to sealing failure and making it impossible to solve the problem of excessive gas levels in a long-term and stable manner. Therefore, in response to the emergency treatment needs of excessive gas levels on the coal surface during continuous coal mining and coal roadway excavation, developing a method that can quickly, efficiently, environmentally friendly, and stably achieve emergency sealing of excessive gas levels on the coal surface is of great practical significance for ensuring coal mine operation safety and improving production efficiency. Summary of the Invention

[0003] The purpose of this invention is to develop a method for emergency sealing of excessive gas on the surface of coal seams in a fast, efficient, environmentally friendly and stable manner, so as to ensure the safety of coal mine operations and improve coal mine production efficiency.

[0004] To achieve the above objectives, the present invention is implemented according to the following technical solution: An emergency sealing method for excessive gas levels on the surface of coal seams includes the following steps: S1. Selection of coating: Select a coating with a porosity of <5% after curing, an adhesion of >1.5MPa, stable operation for more than 12 months at room temperature, water resistance and a temperature range of -10~60℃ in a thickness of 0.5-1mm. S2. Pretreatment: Simple filling treatment is performed on obvious macroscopic cracks on the surface of the coal body; S3. Mixing the coating: Dilute the coating with water to a viscosity of 200~300mPa•s, stir evenly, pour into the storage tank of the spraying equipment, and let stand for 5 minutes to remove air bubbles. S4. Spraying or spraying: Use a high-pressure airless sprayer for spraying or a dust-removing sprayer for spraying.

[0005] Preferably, in step S1, the coating comprises the following components by mass percentage: 1.5%~2.0% Sodium dodecyl sulfate (SDS); 5.0%~8.0% silica nanoparticles, wherein the particle size of the silica nanoparticles is 50~100nm; 3.0%~5.0% polyvinyl alcohol (PVA), wherein the molecular weight of the polyvinyl alcohol (PVA) is 1700~2000; 0.5%~1.0% sodium carboxymethyl cellulose (CMC); 0.3%~0.5% boric acid; 0.2%~0.5% silane coupling agent; 0.1%~0.2% defoamer; The remainder is deionized water.

[0006] Preferably, in step S1, the defoamer is an organosilicon defoamer. It should be noted that other types of defoamers, such as polyether defoamers or phosphate ester defoamers, can also be used in this invention. The silane coupling agent is any one of 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropyltriethoxysilane, wherein the commercial name of 3-aminopropyltriethoxysilane is KH550. Preferably, in step S1, the preparation process of the coating includes the following steps: S11. When preparing the mixture, dissolve polyvinyl alcohol (PVA) and sodium carboxymethyl cellulose (CMC) in hot water at 60~80℃ according to the proportion, and stir until completely dissolved to obtain mixture one; S12. After cooling the first mixture to room temperature, add sodium dodecyl sulfate (SDS) and silica nanoparticles in proportion, and disperse by high-speed stirring to obtain the second mixture. S13. Add boric acid, silane coupling agent and defoamer to the mixture in proportion, and stir at low speed until uniform to obtain the emergency sealing method for excessive gas on the coal surface.

[0007] Preferably, in step S12, the high-speed stirring speed is 1000~1500 r / min, and the high-speed stirring time is 30 minutes.

[0008] Preferably, in step S13, the low-speed stirring speed is 300-600 r / min, and the low-speed stirring time is 15 minutes.

[0009] Preferably, in step S2, the filling process includes: selecting a temporary filling material with good fluidity and filling the crack with the material through manual pouring, extrusion injection, or spraying. The temporary filling material includes cement mortar, quick-setting cement grout, or polyurethane foam. For wider cracks, broken coal blocks, cotton yarn, etc. are first filled as a skeleton support, and then the crack is filled with the aforementioned temporary filling material.

[0010] Preferably, in step S4, when using a high-pressure airless sprayer, the nozzle is 30-50cm away from the coal surface, and the sprayer is reciprocated and sprayed evenly at a speed of 0.5-1m / s, forming a 0.5mm thick coating in one pass.

[0011] Preferably, in step S4, for temporary spraying or spraying during the coal breaking process, only one spraying or single spraying is required, and the coating thickness of a single spray or spray is 0.5 mm; for areas with dense cracks, a re-spray can be applied once every 30 minutes, and the total coating thickness does not exceed 1 mm.

[0012] The working principle of this invention: This invention allows for construction without interrupting tunneling or coal mining operations. The material rapidly solidifies to form a durable sealing layer, supporting 24-hour continuous operation and mitigating the impact of traditional gas control measures on production schedules. Sodium dodecyl sulfate (SDS) and silica nanoparticles are the main functional components of the coating. SDS acts as a surfactant, reducing surface tension and enhancing the wetting and adhesion of the coating to the coal surface, while also aiding in the dispersion of the silica nanoparticles. The silica nanoparticles fill the micropores of the coal seam, combining with other components to form a dense network structure that physically seals gas channels. Polyvinyl alcohol (PVA) and sodium carboxymethyl cellulose (CMC) serve as film-forming and binding agents. PVA, as a water-soluble polymeric film-forming agent, enhances the film-forming properties and mechanical strength of the coating, improving its adhesion to the coal face. Sodium carboxymethyl cellulose (CMC) acts as a thickener, adjusting the system viscosity to prevent dripping during spraying and also assisting in suspending the nanoparticles. Boric acid and silane coupling agents are used as crosslinking and stabilizing additives. Boric acid undergoes a crosslinking reaction with polyvinyl alcohol (PVA), improving the coating's water resistance and weathering resistance, and preventing coating failure upon contact with water. Silane coupling agents are used to improve the compatibility of silica nanomaterials with polyvinyl alcohol (PVA), enhancing the structural stability of the composite coating. Defoamers are used to eliminate bubbles generated during stirring or spraying, preventing the formation of pores in the coating that could affect the sealing effect. Deionized water is used as a solvent to dissolve the components and adjust the system concentration to a suitable viscosity for spraying.

[0013] This invention combines physical sealing with interfacial bonding. By sealing cracks on the coal surface and blocking gas seepage channels, it reduces gas outbursts at the source, effectively lowering the gas permeability of the coal. In application, a high-pressure spraying device is used to uniformly spray the aforementioned emergency sealing method for excessive gas on the coal surface, with a viscosity of 200-300 mPa·s, onto the coal wall surface at a spraying pressure of 0.3-0.5 MPa, forming a coating 0.5-1 mm thick. It takes effect after 24 hours of natural drying.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention can quickly, efficiently, environmentally, and stably achieve emergency sealing of excessive gas on the coal surface by forming a dense coating to block coal pores and reduce gas permeability. It provides a safe and stable working environment for continuous coal mining and continuous coal roadway excavation, and is suitable for temporary or short-term gas outburst prevention scenarios in underground coal mines. Attached Figure Description

[0015] Figure 1 The following describes the specific construction process of the present invention in the embodiments. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions herein are used to explain the present invention, but are not intended to limit the present invention.

[0017] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0018] There are no particular restrictions on the purity of any of the raw materials used in this invention; however, it is preferred to use materials with conventional purity levels used in the field.

[0019] Unless otherwise specified, the apparatus used in this invention employs commonly used devices in the field.

[0020] Example 1 like Figure 1 As shown in the figure, this embodiment proposes an emergency sealing method for excessive gas levels on the surface of coal seams, including the following steps: S1. Selection of coating: Select a coating with a porosity of <5% after curing, an adhesion of >1.5MPa, stable operation for more than 12 months at room temperature, water resistance and a temperature range of -10~60℃ in a thickness of 0.5-1mm. S2. Pretreatment: Simple filling treatment is performed on obvious macroscopic cracks on the surface of the coal body; The filling process described in this step includes: selecting a temporary filler material with good fluidity and filling the cracks by manual pouring, extrusion injection, or spraying. The temporary filler material includes cement mortar, quick-setting cement grout, or polyurethane foam. For wider cracks, crushed coal, cotton yarn, etc., are first filled as a framework support, and then the cracks are filled with the aforementioned temporary filler material.

[0021] S3. Mixing the coating: Dilute the coating with water to a viscosity of 200~300mPa•s, stir evenly, pour into the storage tank of the spraying equipment, and let stand for 5 minutes to remove air bubbles. S4. Spraying: A high-pressure airless sprayer is used for spraying. The working pressure of the high-pressure airless sprayer is 15~20MPa, the flow rate is 5~10L / min, and the suitable nozzle diameter is 0.8~1.2mm. During spraying, the nozzle is 30~50cm away from the coal surface, and the spray is applied evenly in a reciprocating motion at a speed of 0.5~1m / s, forming a 0.5mm thick coating in a single pass. For temporary spraying during coal breaking, only a single spray is required; for areas with dense fractures, a second spray can be applied every 30 minutes, with the total coating thickness not exceeding 1mm.

[0022] Continuing with the above embodiments, in step S1, the coating comprises the following components by mass percentage: 1.5% Sodium dodecyl sulfate (SDS); 8.0% silica nanoparticles, wherein the silica nanoparticles have a particle size of 50~100nm; 3.0% polyvinyl alcohol (PVA), wherein the molecular weight of polyvinyl alcohol (PVA) is 1700~2000; 0.8% Sodium carboxymethyl cellulose (CMC); 0.3% boric acid; 0.5% silane coupling agent, wherein the silane coupling agent is 3-aminopropyltriethoxysilane, whose trade name is KH550; 0.1% silicone defoamer; The remainder is deionized water.

[0023] Specifically, the above coating is prepared according to the following steps: S11. When preparing the mixture, dissolve polyvinyl alcohol (PVA) and sodium carboxymethyl cellulose (CMC) in hot water at 60~80℃ according to the proportion, and stir until completely dissolved to obtain mixture one; S12. After cooling the first mixture to room temperature, add sodium dodecyl sulfate (SDS) and silica nanoparticles in proportion, and disperse by high-speed stirring to obtain the second mixture. S13. Add boric acid, silane coupling agent and defoamer to the mixture in proportion, and stir at low speed until uniform to obtain the emergency sealing method for excessive gas on the coal surface.

[0024] Specifically, in step S12, the high-speed stirring speed is 1000~1500 r / min, and the high-speed stirring time is 30 minutes; in step S13, the low-speed stirring speed is 300-600 r / min, and the low-speed stirring time is 15 minutes.

[0025] Example 2 The only difference between this embodiment and Embodiment 1 is the composition of the coating in step S1. The emergency sealing method for excessive gas on the surface of coal seams proposed in this embodiment includes the following components by mass percentage: 1.8% Sodium dodecyl sulfate (SDS); 6.0% silica nanoparticles; 5.0% Polyvinyl alcohol (PVA); 0.5% Sodium Carboxymethyl Cellulose (CMC); 0.4% boric acid; 0.3% silane coupling agent, wherein the silane coupling agent is 3-aminopropyltriethoxysilane, whose trade name is KH550; 0.15% silicone defoamer; The remainder is deionized water.

[0026] Example 3 The only difference between this embodiment and Embodiment 1 is the composition of the coating in step S1. The emergency sealing method for excessive gas on the surface of coal seams proposed in this embodiment includes the following components by mass percentage: 2.0% Sodium dodecyl sulfate (SDS); 5.0% silica nanoparticles; 4.0% Polyvinyl alcohol (PVA); 1.0% Sodium carboxymethyl cellulose (CMC); 0.5% boric acid; 0.2% silane coupling agent, wherein the silane coupling agent is 3-aminopropyltriethoxysilane, whose trade name is KH550; 0.2% silicone defoamer; The remainder is deionized water.

[0027] After applying the emergency sealing methods for excessive gas levels on the coal surface prepared in Examples 1-3, testing revealed that: The material is suitable for high-pressure spraying, with rapid curing speed (complete curing in 24 hours), and does not affect the normal advance rhythm of the tunneling face. After curing, the coating porosity is <5%, reducing gas emission by 70%~90% in coal bodies dominated by micro-fractures and by 50%~70% in coal bodies with coexisting medium-fractures, while reducing gas permeability by 1~2 orders of magnitude. The coating adhesion is >1.5MPa, and it is not easy to fall off when the coal body is slightly deformed (displacement <2mm). It can work stably for more than 12 months at room temperature, is water-resistant, and has a temperature range of -10~60℃, adapting to the complex underground environment. Moreover, the material has no irritating odor, does not produce toxic volatiles, and has a biodegradability rate of >90%, meeting the safety standards for use in underground coal mines.

[0028] This method has no impact on coal quality, and the construction process is wet, which does not generate dust and poses no significant occupational hazards to workers. It meets national standards. This invention provides a stable gas control solution for continuous coal mining and coal roadway excavation through the dual effects of "sealing + seepage control". It not only ensures operational safety but also improves production efficiency, making it an ideal choice for high-gas mines to achieve a "win-win situation of safety and efficiency".

[0029] This invention can be constructed without interrupting tunneling or coal mining processes. After the material solidifies rapidly, it forms a durable sealing layer, supporting 24-hour continuous operation and solving the impact of traditional gas control measures on production progress.

[0030] First, it can precisely block gas outburst channels: the silica nanoparticles in the material can quickly fill the tiny cracks of 0.1~100μm on the surface of the coal body, and together with the polymer binder, form a dense silicon-organic composite coating, which directly blocks the seepage path of gas from the inside of the coal body to the working space, reducing the amount of gas outburst from surface cracks by more than 80%.

[0031] Secondly, it can reduce the number of times gas exceeds the limit: by stabilizing and controlling the gas release rate on the coal surface, the gas concentration fluctuation at the tunneling face and coal mining face can be reduced, thereby reducing the number of times gas exceeds the limit by 60% to 90% and avoiding shutdowns and rectifications caused by exceeding the limit.

[0032] Ultimately, it ensures continuous operation: construction can be carried out without interrupting tunneling or coal mining processes, and the material solidifies quickly to form a durable sealing layer, supporting 24-hour continuous operation and solving the impact of traditional gas control measures on production progress.

[0033] Sodium dodecyl sulfate (SDS) and silica nanoparticles are the main functional components of the coating. SDS acts as a surfactant, reducing surface tension and enhancing the wetting and adhesion of the coating to the coal surface, while also aiding in the dispersion of the silica nanoparticles. The silica nanoparticles fill the micropores of the coal body, combining with other components to form a dense network structure that physically blocks gas channels. Polyvinyl alcohol (PVA) and sodium carboxymethyl cellulose (CMC) are used as film-forming and binding agents. PVA, as a water-soluble polymeric film-forming agent, enhances the film-forming properties and mechanical strength of the coating, improving its adhesion to the coal wall. Sodium carboxymethyl cellulose (CMC) acts as a thickener, adjusting the system viscosity to prevent dripping during spraying and also assisting in suspending the nanoparticles. Boric acid and silane coupling agents are used as crosslinking and stabilizing agents. Boric acid undergoes a crosslinking reaction with PVA, improving the coating's water resistance and weathering resistance, preventing coating failure upon contact with water. Silane coupling agents are used to improve the compatibility of silica nanomaterials with polyvinyl alcohol (PVA) and enhance the structural stability of the composite coating. Defoamers are used to eliminate bubbles generated during stirring or spraying, preventing the formation of pores in the coating that could affect the sealing effect. Deionized water is used as a solvent to dissolve the components and to adjust the system concentration to a suitable viscosity for spraying.

[0034] This invention combines physical sealing with interfacial bonding. By sealing cracks on the coal surface and blocking gas seepage channels, it reduces gas outbursts at the source, effectively lowering the gas permeability of the coal. In application, a high-pressure spraying device is used to uniformly spray the aforementioned emergency sealing method for excessive gas on the coal surface, with a viscosity of 200-300 mPa·s, onto the coal wall surface at a spraying pressure of 0.3-0.5 MPa, forming a coating 0.5-1 mm thick. It takes effect after 24 hours of natural drying.

[0035] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A method for emergency sealing of excessive gas levels on the surface of coal seams, characterized in that, Includes the following steps: S1. Selection of coating: Select a coating with a porosity of <5% after curing, an adhesion of >1.5MPa, stable operation for more than 12 months at room temperature, water resistance and a temperature range of -10~60℃ in a thickness of 0.5-1mm. S2. Pretreatment: Simple filling treatment is performed on obvious macroscopic cracks on the surface of the coal body; S3. Mixing the coating: Dilute the coating with water to a viscosity of 200~300mPa•s, stir evenly, pour into the storage tank of the spraying equipment, and let stand for 5 minutes to remove air bubbles. S4. Spraying or spraying: Use a high-pressure airless sprayer for spraying or a dust-removing sprayer for spraying.

2. The method for emergency sealing of excessive gas levels on the surface of a coal seam according to claim 1, characterized in that, In step S1, the coating comprises the following components by mass percentage: 1.5%~2.0% Sodium dodecyl sulfate (SDS); 5.0%~8.0% silica nanoparticles, wherein the particle size of the silica nanoparticles is 50~100nm; 3.0%~5.0% polyvinyl alcohol (PVA), wherein the molecular weight of polyvinyl alcohol (PVA) is 1700~2000; 0.5%~1.0% sodium carboxymethyl cellulose (CMC); 0.3%~0.5% boric acid; 0.2%~0.5% silane coupling agent; 0.1%~0.2% defoamer; The remainder is deionized water.

3. The emergency sealing method for excessive gas levels on the surface of a coal seam according to claim 2, characterized in that, In step S1, the defoamer is an organosilicon defoamer, and the silane coupling agent is any one of 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropyltriethoxysilane.

4. A method for emergency sealing of excessive gas levels on the surface of a coal seam according to claim 2 or 3, characterized in that, In step S1, the preparation process of the coating includes the following steps: S11. When preparing the mixture, dissolve polyvinyl alcohol (PVA) and sodium carboxymethyl cellulose (CMC) in hot water at 60~80℃ according to the proportion, and stir until completely dissolved to obtain mixture one; S12. After cooling the first mixture to room temperature, add sodium dodecyl sulfate (SDS) and silica nanoparticles in proportion, and disperse by high-speed stirring to obtain the second mixture. S13. Add boric acid, silane coupling agent and defoamer to the mixture in proportion, and stir at low speed until uniform to obtain the emergency sealing method for excessive gas on the coal surface.

5. The emergency sealing method for excessive gas levels on the surface of a coal seam according to claim 4, characterized in that, In step S12, the high-speed stirring speed is 1000~1500 r / min, and the high-speed stirring time is 30 minutes.

6. The emergency sealing method for excessive gas levels on the surface of a coal seam according to claim 4, characterized in that, In step S13, the low-speed stirring speed is 300-600 r / min, and the low-speed stirring time is 15 minutes.

7. The emergency sealing method for excessive gas levels on the surface of a coal seam according to claim 1, characterized in that, In step S2, the filling process includes: selecting a temporary filling material with good fluidity and filling the crack with the material by manual pouring, extrusion injection or spraying. The temporary filling material includes cement mortar, quick-setting cement grout or polyurethane foam.

8. The emergency sealing method for excessive gas levels on the surface of a coal seam according to claim 1, characterized in that, In step S4, when using a high-pressure airless sprayer, the nozzle is 30-50cm away from the coal surface, and the sprayer is reciprocated and sprayed evenly at a speed of 0.5-1m / s, forming a 0.5mm thick coating in one pass.

9. The emergency sealing method for excessive gas levels on the surface of a coal seam according to claim 1, characterized in that, In step S4, for temporary spraying or spraying during the coal breaking process, only one spraying or single spraying is required, and the coating thickness of a single spray or spray is 0.5mm; for areas with dense cracks, a second spray can be applied every 30 minutes, and the total coating thickness shall not exceed 1mm.

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