Coal mine fire preventing and extinguishing material and coal mine safe mining method based on same

Abstract

The invention relates to the technical field of coal mining, in particular to a coal mine fire preventing and extinguishing material and a coal mine safety mining method based on the coal mine fire preventing and extinguishing material, and the coal mine fire preventing and extinguishing material comprises the following components in parts by mass: 88-92 parts of filler and 8-12 parts of functional filler; the functional filler is a compound of nanoscale ferrous oxide and composite metal hydroxide; the filling material is porous net-shaped framework slurry. Through porous skeleton physical plugging, nanoscale ferrous oxide high-temperature active oxygen consumption, composite metal hydroxide thermal decomposition cooling and reinforced plugging, a synergistic prevention and control system is constructed, fire occurrence and reburning are effectively restrained, and safe production is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of coal mining technology, specifically to a coal mine fire prevention and extinguishing material and a coal mine safe mining method based thereon. Background Technology

[0002] Coal mine fires are one of the most significant safety hazards during coal mining. They are often caused by the oxidation reaction of coal in prolonged contact with oxygen, gradually accumulating heat and triggering spontaneous combustion, or by electrical faults or blasting operations that ignite open flames. These fires not only waste coal resources but can also induce secondary disasters such as gas explosions and poisoning, seriously threatening safe coal mine production. To prevent and control coal mine fires, various fire prevention and extinguishing materials and related technologies have been developed, mainly including traditional grouting materials, gel-based materials, and single-function flame retardants.

[0003] Traditional grouting materials (such as yellow mud slurry and fly ash slurry) achieve fire prevention and sealing by filling coal fissures and blocking air leakage channels. However, these materials have low porosity and poor fluidity, making it difficult to penetrate deep into the goaf. They also lack active oxygen consumption and cooling functions, making it difficult to inhibit coal oxidation and temperature rise in the early stages of a fire. During the fire development stage, they are prone to high-temperature cracking, leading to sealing failure and a high risk of reignition. While gel-based materials (such as polyacrylamide gel and composite colloids) can form a continuous sealing layer, their high-temperature stability is insufficient. They are prone to thermal decomposition above 200°C, leading to structural collapse. Furthermore, they rely solely on physical sealing and lack synergy with oxygen consumption and cooling functions, making it impossible to quickly reduce the temperature and oxygen concentration in the fire area. Therefore, their effectiveness in controlling fires during the development stage is limited.

[0004] In addition, existing fire prevention and extinguishing materials generally suffer from the problem of "single function and poor synergy": they either only focus on physical leak sealing or only focus on cooling or oxygen consumption, making it difficult to form a synergistic prevention and control system.

[0005] Therefore, the present invention provides a coal mine fire prevention and extinguishing material and a coal mine safe mining method based thereon to solve the above problems. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a coal mine fire prevention and extinguishing material and a coal mine safe mining method based thereon. This material solves the problems of limited functionality and poor synergy of existing coal mine fire prevention and extinguishing materials, achieving a three-pronged approach of "leak plugging-oxygen depletion-cooling" to effectively curb the occurrence, development, and reignition risks of coal mine fires, and providing reliable technical support for safe mining throughout the entire coal mine lifecycle.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: a coal mine fire prevention and extinguishing material, the components of which include, by mass percentage: 88-92 parts of filler and 8-12 parts of functional filler; the functional filler is a compound of nano-sized ferrous oxide and composite metal hydroxide; the filler is a porous mesh skeleton slurry.

[0008] Furthermore, the mass fraction ratio of nano-ferrous oxide to composite metal hydroxide is 1:1.5 - 2.5.

[0009] Furthermore, the filler is composed of the following components by mass fraction ratio: 28 - 32 parts of modified polyacrylamide, 23 - 27 parts of diatomaceous earth, 16 - 20 parts of expanded perlite, 7 - 9 parts of composite foaming agent, 4 - 6 parts of polyethylene glycol, 3 - 5 parts of hydroxypropyl methylcellulose, and 8 - 12 parts of water.

[0010] Furthermore, the composite foaming agent is a compound of sodium bicarbonate and citric acid, and the mass fraction ratio of sodium bicarbonate to citric acid is 1:1.2.

[0011] Furthermore, the composite metal hydroxide is a compound of Mg(OH)2 and Al(OH)3, and the mass fraction ratio of Mg(OH)2 to Al(OH)3 is 1: |1.

[0012] Furthermore, a coal mine safety mining method includes the following steps: Step 1, material preparation: Prepare a porous network skeleton slurry, and then uniformly mix the functional filler dispersion into the porous network skeleton slurry and stir to form a uniform composite slurry; Step 2, skeleton pouring and shaping: Inject the composite slurry into the target area of the coal mine through high-pressure grouting technology and cure it at normal temperature for 2 - 3 hours to form a porous network skeleton.

[0013] Furthermore, in Step 1, the functional filler preparation process, the porous network skeleton slurry preparation process, and the mixing process are as follows: Functional filler preparation: Take nano-ferrous oxide and composite metal hydroxide according to the mass fraction ratio of 1:1.5 - 2.5 parts, mix them, add 2 - 3 parts of silane coupling agent, and then put them into deionized water for ultrasonic dispersion to form a uniform dispersion, and set aside; Porous network skeleton slurry preparation: Heat 8 - 12 parts of water to 50 - 60 °C, sequentially add 28 - 32 parts of modified polyacrylamide and 3 - 5 parts of hydroxypropyl methylcellulose, stir until completely dissolved, then add 23 - 27 parts of diatomaceous earth and 16 - 20 parts of expanded perlite, continuously stir for 15 - 25 minutes, and finally add 7 - 9 parts of composite foam |ing agent and stir to form a porous network skeleton slurry; Mixing process: Pour the dispersion of the functional filler into the skeleton slurry, and then stir for 20 - 30 minutes to obtain a uniform coal mine fire prevention and extinguishing composite slurry, and set aside.

[0014] Furthermore, in the functional filler preparation process, the silane coupling agent adopts KH-550.

[0015] Furthermore, in step two, before mining, the distribution of fractures in the goaf and the range of loose coal in the roadway are detected by drilling. Grouting holes are arranged at the upper and lower corners, the edge of the goaf, and the fault fracture zone. Then, the coal mine fire prevention and extinguishing composite grout is injected into the grouting pipe using high-pressure grouting technology at a uniform pressure of 1.5 to 2.0 MPa. After grouting is completed, it is cured at room temperature for 2 to 3 hours to allow the coal mine fire prevention and extinguishing composite grout to foam, solidify, and form.

[0016] Furthermore, the diameter of the grouting holes is 80-100 mm, the hole spacing is 1-6 meters, and the hole depth is 1-8 meters.

[0017] The above-mentioned solution has the following beneficial effects: In this solution, the porous mesh skeleton grout serves as the core carrier and physical leak-sealing basis of the fire prevention and extinguishing system. It is composed of modified polyacrylamide, diatomaceous earth, expanded perlite and other components, and foamed by a composite foaming agent to form a three-dimensional interconnected porous structure similar to human skeleton. It has both excellent fluidity and molding strength, which can firmly fix the functional filler to prevent it from falling off or agglomerating, and can also physically block the channels for external oxygen to replenish the coal body and reduce air leakage. It provides a stable and sealed environment for the subsequent oxygen consumption and cooling functions, effectively solving the problems of poor fluidity, insufficient penetration and easy cracking failure of traditional grouting materials. Nano-sized ferrous oxide, as the core component for active oxygen consumption, exhibits excellent dispersibility after modification with silane coupling agent KH-550. It is uniformly distributed in the pores of the framework and matrix. At a critical temperature above 60℃ (the initial temperature of a coal mine fire), it can rapidly undergo an oxidation reaction with oxygen, actively consuming oxygen in the high-temperature area and around the coal body. This cuts off the necessary conditions for coal oxidation and heating from the source, reduces the problem of being unable to access oxygen due to being encased in coal, significantly improves oxygen consumption efficiency, and inhibits the initiation of fires. Composite metal hydroxides, as highly efficient cooling and secondary sealing components, are composed of Mg(OH)2 and Al(OH)3 in a 1:1 ratio. They exhibit stepwise thermal decomposition characteristics, with Al(OH)3 decomposing first above 200℃ and Mg(OH)2 following suit above 340℃. The total heat absorption is ≥1800J / g, which can continuously absorb a large amount of heat from the fire area, rapidly reducing the coal temperature to slow the spread of the fire. The decomposition products are inert solid particles of MgO and Al2O3, as well as moisture, without the generation of toxic gases. They can also fill the micropores of the porous skeleton and the newly added coal body fissures after grouting, forming a secondary sealing barrier and further improving the sealing effect.

[0018] In the initial stage of combustion and high-temperature (fire) scenarios, the three components form a "dynamically progressive, closed-loop synergistic" fire prevention and extinguishing system, achieving precise prevention and control throughout the entire cycle: Under normal conditions, proactive prevention is achieved, with the porous mesh skeleton completing physical sealing to reduce oxygen supply; in the initial stage of a fire (temperature ≥60℃), nano-grade ferrous oxide simultaneously initiates active oxygen consumption, rapidly reducing the regional oxygen concentration and inhibiting further oxidation and temperature rise of the coal body; if the fire develops (temperature ≥200℃), the composite metal hydroxide will initiate thermal decomposition to continuously absorb heat and cool down, reducing the expansion of the fire. Its decomposition products simultaneously fill the skeleton and micro-cracks in the coal body, enhancing the sealing effect to reduce oxygen re-infiltration; the three components work together to form a dynamic closed loop of "skeleton sealing and oxygen reduction → ferrous oxide active oxygen consumption → hydroxide cooling + product sealing," which not only blocks the oxygen supply path but also consumes existing oxygen and rapidly cools down the fire, fundamentally curbing the occurrence, development, and reignition of the fire, solving the core pain points of existing materials being single-function, poorly synergistic, and unable to adapt to the entire stage of fire prevention and control.

[0019] Additional aspects and advantages of the invention 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 the invention. Attached Figure Description

[0020] Figure 1 This is a schematic flowchart illustrating an embodiment of the safe coal mining method of the present invention. Detailed Implementation

[0021] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] The following detailed description illustrates the specific implementation method: Example 1:

[0025] A coal mine fire prevention and extinguishing material, comprising, by mass percentage: 88-92 parts filler and 8-12 parts functional filler.

[0026] Specifically, the filler comprises the following components by mass percentage: 28-32 parts modified polyacrylamide, 23-27 parts diatomaceous earth, 16-20 parts expanded perlite, 7-9 parts composite foaming agent, 4-6 parts polyethylene glycol, 3-5 parts hydroxypropyl methylcellulose, and 8-12 parts water. The composite foaming agent is a mixture of sodium bicarbonate and citric acid, with a mass ratio of sodium bicarbonate to citric acid of 1:1.2. Ultimately, a porous network skeleton slurry is formed.

[0027] Specifically, the functional filler is a compound of nano-sized ferrous oxide and a composite metal hydroxide, with a mass ratio of 1:1.5 to 2.5 parts. The composite metal hydroxide is a compound of Mg(OH)₂ and Al(OH)₃, with a mass ratio of Mg(OH)₂ to Al(OH)₃ of 1:1.

[0028] Example 2:

[0029] As attached Figure 1 As shown, a safe coal mining method, based on the coal mine fire prevention and extinguishing material described in Example 1, includes the following steps: Step 1, Material Preparation: Prepare a porous mesh framework slurry, then uniformly mix the functional filler dispersion into the porous mesh framework slurry and stir to form a homogeneous composite slurry. The specific process is as follows: The preparation process of the functional filler is as follows: Take nano-sized ferrous oxide and composite metal hydroxide at a mass ratio of 1:1.5 to 2.5 parts, mix them, add 2 to 3 parts by mass of silane coupling agent KH-550, and then put them into deionized water for ultrasonic dispersion to form a uniform dispersion for later use. The preparation process of the porous network skeleton slurry is as follows: Heat 8 - 12 parts of water to 50 - 60 °C, and successively add 28 - 32 parts of modified polyacrylamide and 3 - 5 parts of hydroxypropyl methylcellulose. After stirring until completely dissolved, add 23 - 27 parts of diatomite and 16 - 20 parts of expanded perlite, continuously stir for 15 - 25 minutes, and finally add 7 - 9 parts of composite foaming agent and stir to form the porous network skeleton slurry; The mixing process is as follows: Pour the dispersion of the functional filler into the skeleton slurry and stir for another 20 - 30 minutes to obtain a uniform coal mine fire prevention and extinguishing composite slurry for standby.

[0030] Step 2, skeleton casting and shaping: Inject the composite slurry into the target area of the coal mine through high-pressure grouting technology and maintain it for 2 - 3 hours at room temperature to form a porous network skeleton. Specifically, in Step 2, before mining, detect the fissure distribution in the goaf and the range of loose coal in the roadway through drilling, and arrange grouting holes (the aperture of the grouting hole is 80 - 100 mm, the hole spacing is 1 - 6 meters, and the hole depth is 1 - 8 meters) at the upper and lower corners, the edge of the goaf, and the fault fracture zone; then, through high-pressure grouting technology, inject the coal mine fire prevention and extinguishing composite slurry into the grouting pipe and grout at a uniform speed with a pressure of 1.5 - 2.0 MPa; after grouting is completed, maintain it for 2 - 3 hours in a room temperature environment to make the coal mine fire prevention and extinguishing composite slurry foam and solidify.

[0031] The specific implementation process is as follows: After completing the arrangement of grouting holes and the pouring and maintenance of the composite slurry before mining, a porous network skeleton layer (nano-scale ferrous oxide and composite metal hydroxides are evenly dispersed in the pores and matrix inside the skeleton) is formed, which is distributed at the edge of the goaf, the upper and lower corners, and the fault fracture zone to form a continuous protection system.

[0032] When coal spontaneous combustion or a fire occurs and the fire spreads to the porous network skeleton layer, first, the porous network skeleton layer plays a strong physical fire-blocking role through "space separation + maze effect". After the flame contacts the skeleton layer, it will be naturally separated into countless independent tiny pores. The limited pore space greatly shortens the diffusion path of the flame. At the same time, the nano-scale ferrous oxide distributed in the pores actively consumes the oxygen in the unit volume (oxidation reaction with the oxygen in the area, 4FeO + O2 → 2Fe2O3), further restricting the flame propagation rate and combustion intensity. When the local oxygen concentration drops below 15%, the flame cannot penetrate the skeleton layer and spread to the deep coal body due to lack of sufficient oxygen support, achieving physical isolation and range control of the fire.

[0033] If the fire is not completely contained and the regional temperature continues to rise to 220℃, the composite metal hydroxide (Mg(OH)2 and Al(OH)3 in a 1:1 ratio) initiates a stepwise thermal decomposition reaction. First, Al(OH)3 decomposes (2Al(OH)3 → Al2O3 + 3H2O↑), absorbing a large amount of heat (1960 J / g) during the decomposition process. This rapidly lowers the local temperature of the fire zone, reducing the heating rate from 0.8℃ / min to 0.3℃ / min, effectively curbing the spread of the fire. When the temperature further rises to 350℃, Mg(OH)2 continues to decompose (Mg(OH)2 → MgO + H2O↑), absorbing an additional 1870 J / g of heat, maintaining the cooling effect on the fire zone and reducing the risk of severe coal oxidation or gas explosion caused by high temperatures. Simultaneously, the gaseous water formed during decomposition diffuses within the porous framework, not only occupying part of the fire zone and compressing the effective oxygen content, but also diluting the concentration of flammable gases such as methane, reducing the risk of gas explosion.

[0034] In addition, the generated inert solid particles of MgO and Al2O3 fill the tiny pores of the porous mesh skeleton layer, the new cracks generated by coal oxidation, and the tiny channels that may be missed during grouting with the hot air flow, forming a dense secondary sealing barrier, further reducing oxygen supply, complementing the initial sealing of the porous mesh skeleton layer, and enhancing the sealing effect.

[0035] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A fire prevention and extinguishing material for coal mines, characterized in that, The components, by mass percentage, include: 88-92 parts of filler and 8-12 parts of functional filler; the functional filler is a compound of nano-sized ferrous oxide and composite metal hydroxide; the filler is a porous mesh skeleton slurry.

2. The coal mine fire prevention and extinguishing material according to claim 1, characterized in that, The mass ratio of nano-sized ferrous oxide to composite metal hydroxide is 1:1.5 to 2.

5.

3. The coal mine fire prevention and extinguishing material according to claim 2, characterized in that, The filler is composed of the following components in parts by mass: 28-32 parts modified polyacrylamide, 23-27 parts diatomaceous earth, 16-20 parts expanded perlite, 7-9 parts composite foaming agent, 4-6 parts polyethylene glycol, 3-5 parts hydroxypropyl methylcellulose, and 8-12 parts water.

4. The coal mine fire prevention and extinguishing material according to claim 3, characterized in that, The composite foaming agent is a mixture of sodium bicarbonate and citric acid, with a mass ratio of sodium bicarbonate to citric acid of 1:1.

2.

5. The coal mine fire prevention and extinguishing material according to claim 4, characterized in that, The composite metal hydroxide is a mixture of Mg(OH)2 and Al(OH)3, with a mass ratio of Mg(OH)2 to Al(OH)3 of 1:

1.

6. A method for safe coal mining, comprising the coal mine fire prevention and extinguishing material according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1, Material preparation: Prepare a porous mesh skeleton slurry, then uniformly mix the functional filler dispersion into the porous mesh skeleton slurry and stir to form a uniform composite slurry; Step 2, skeleton casting and shaping: The composite grout is injected into the target area of ​​the coal mine through high-pressure grouting technology, and cured at room temperature for 2-3 hours to form a porous mesh skeleton.

7. The method for safe coal mining according to claim 6, characterized in that, In step one, the preparation processes of the functional filler, the porous mesh skeleton slurry, and the mixing process are as follows: Functional filler preparation process: Take nano-sized ferrous oxide and composite metal hydroxide at a mass ratio of 1:1.5 to 2.5 parts, mix them, add 2 to 3 parts by mass of silane coupling agent, and then put them into deionized water for ultrasonic dispersion to form a uniform dispersion for later use. Preparation process of porous mesh skeleton slurry: Heat 8-12 parts of water to 50-60℃, add 28-32 parts of modified polyacrylamide and 3-5 parts of hydroxypropyl methylcellulose in sequence, stir until completely dissolved, then add 23-27 parts of diatomaceous earth and 16-20 parts of expanded perlite, continue stirring for 15-25 minutes, and finally add 7-9 parts of composite foaming agent and stir to form porous mesh skeleton slurry; Mixing process: Pour the dispersion of the functional filler into the skeleton slurry and stir for 20-30 minutes to obtain the coal mine fire prevention and extinguishing composite slurry for later use.

8. The method for safe coal mining according to claim 7, characterized in that, In the preparation of functional fillers, KH-550 is used as the silane coupling agent.

9. The method for safe coal mining according to claim 8, characterized in that, In step two, before mining, the distribution of fractures in the goaf and the range of loose coal in the roadway are detected by drilling. Grouting holes are arranged at the upper and lower corners, the edge of the goaf, and the fault fracture zone. Then, the coal mine fire prevention and extinguishing composite grout is injected into the grouting pipe using high-pressure grouting technology at a uniform pressure of 1.5 to 2.0 MPa. After grouting is completed, it is cured at room temperature for 2 to 3 hours to allow the coal mine fire prevention and extinguishing composite grout to foam, solidify, and form.

10. The method for safe coal mining according to claim 9, characterized in that, The diameter of the grouting holes is 80-100mm, the hole spacing is 1-6 meters, and the hole depth is 1-8 meters.

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