Fire preventing and extinguishing method during recovery period of stope face

Abstract

The invention provides a fire preventing and extinguishing method during recovery of a stope face, which relates to the technical field of coal mine operation and comprises the following steps: adhering a plurality of layers of closed flame-retardant materials to a polyester fiber net laid on a recovery channel of the stope face to form a closed net; when the goaf is recovered to a mining stopping position, the goaf is completely sealed by the sealing net, so that a sealed oxygen isolation space is formed; upper and lower corners of the working face are blocked, and the oxygen supply condition is further blocked; a layer of closed flame-retardant material is adhered to a polyester fiber net laid on a working face recovery channel, after the polyester fiber net arrives at a mining stopping position, the closed net completely closes a goaf, and meanwhile, the upper corner and the lower corner of the working face are blocked, oxygen supply conditions are blocked, and isolation and closing are carried out; then nitrogen and liquid nitrogen injection or pressure injection of liquid carbon dioxide is assisted to reduce the oxygen content of the goaf, finally the purpose of fire prevention and extinguishment is achieved, safe recovery of the working face is guaranteed, and the safety of personnel and equipment is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of coal mine operation, and in particular to a fire prevention and extinguishing method during the recovery period of a mining working face. Background Art

[0002] During the coal mining process, the fire prevention and extinguishing of coal seams prone to spontaneous combustion has always been an important factor restricting safe production, especially in the entire cycle from the end of the working face to the completion of the construction of the recovery channel and then to the completion of equipment recovery. The total construction period is often as long as 50-60 days, while the ignition period of coal seams prone to spontaneous combustion is usually 30-40 days; When encountering this situation, most mines generally adopt passive fire prevention and extinguishing measures such as grouting, nitrogen injection, sealing upper and lower corners or drilling and grouting. However, it is often difficult to effectively curb the occurrence of fire. Some mines even still catch fire after taking measures. In order to recover the work, they take the risk of fire or race against the fire to recover the working face. This not only increases the production risk, but may also cause equipment damage and casualties, bringing huge economic losses and safety pressure to coal mining enterprises. The main reason is that during the period when the working face is used as a recovery channel, the support stops and the working face is open. There are spatial conditions for storing heat and continuous oxygen supply. Therefore, the present invention proposes a fire prevention and extinguishing method during the recovery of the mining working face to solve the problems existing in the prior art. Summary of the invention

[0003] In response to the above problems, the present invention proposes a method for preventing and extinguishing fire during the recovery of the mining face. The method for preventing and extinguishing fire during the recovery of the mining face can isolate and seal all the goafs of the working face, completely block the oxygen supply conditions, and at the same time assist in reducing the oxygen content in the goaf by injecting nitrogen, liquid nitrogen or liquid carbon dioxide, thereby ultimately achieving the purpose of preventing and extinguishing fire and ensuring the safe recovery of the working face.

[0004] To achieve the purpose of the present invention, the present invention is implemented by the following technical scheme: a method for preventing and extinguishing fire during the recovery of a mining face, comprising the following steps: S1: Several layers of closed flame retardant material are adhered to the polyester fiber net laid on the recovery channel of the working surface to form a closed net; S2: When the mining is stopped, the closed net will completely seal the goaf to form a closed oxygen-isolated space; S3: Block the upper and lower corners of the working surface to further block the oxygen supply conditions; S4: Inject inert medium to reduce the oxygen content in the goaf and inhibit spontaneous combustion of coal seams; S5: During the sealing and gas injection process, continuously monitor the oxygen concentration and temperature changes in the goaf to evaluate the effectiveness of fire prevention and extinguishing measures.

[0005] A further improvement is that in S1, the closed flame retardant material is flame retardant cloth or air duct cloth.

[0006] A further improvement is that: S1 comprises the following steps: On the recovery channel of the working face, firstly lay a layer of polyester fiber net, and control the width of the polyester fiber net to horizontally adapt to cover the width of the entire goaf; At least one layer of closed flame retardant material is adhered to the polyester fiber web to form a closed web.

[0007] A further improvement is that: S2 comprises the following steps: When the working face is recovered to the stop-mining position, the laid closed net is used to cover the goaf to form a closed oxygen-isolating space; Control and seal seamless gaps by adding sealing strips and using sealants.

[0008] A further improvement is that in S2, after sealing, the oxygen concentration in the goaf is continuously monitored. When an abnormal increase in the oxygen concentration is found, the sealing operation is performed again. At the same time, sufficient fire-fighting equipment is prepared to deal with emergencies.

[0009] A further improvement is that: S3 comprises the following steps: Prepare flame retardant foam glue, sealant and support frame; Clean the upper and lower corners to remove debris and coal dust; Install the support frame according to the shape and size of the upper and lower corners; Lay the flame retardant foam adhesive on the support frame, making sure the material completely covers the openings in the upper and lower corners; Use sealant to fill the gaps between the flame retardant foam adhesives. During the filling process, the sealant is fully penetrated and cured to form a sealing layer; Once completed, inspect the blocked area to ensure there are no gaps or openings that were missed.

[0010] A further improvement is that in said S4, the injected inert medium comprises a mixture of one or more of nitrogen, liquid nitrogen and liquid carbon dioxide.

[0011] A further improvement is that: said S4 comprises the following steps: Prepare inert medium and first evaluate the safety status of the goaf, including oxygen concentration, temperature, and coal seam spontaneous combustion tendency indicators; Determine the injection point based on the shape and size of the goaf, and choose an area with a high risk of spontaneous combustion of the coal seam; Inject inert medium and evenly distribute it in the goaf; Continuously monitor the oxygen concentration and temperature changes in the goaf, and adjust the number of injection points and injection speed based on the variables.

[0012] A further improvement is that in S5, the oxygen concentration is monitored by an oxygen concentration monitor; the temperature is monitored by a temperature sensor or an infrared thermometer. Before monitoring, the monitoring point is determined based on the risk area of ​​spontaneous combustion of the coal seam, the characteristics of the gas flow and the coverage of the monitoring equipment.

[0013] Further improvement is: in said S5, the oxygen concentration and temperature changes in the goaf are continuously monitored. During the monitoring process, data are recorded regularly, and data fluctuations are noted. The data trends, the occurrence of abnormal values ​​and their causes are analyzed to evaluate the effectiveness of fire prevention and extinguishing measures. When the oxygen concentration and temperature are kept within a safe range and there is no obvious upward trend, the fire prevention and extinguishing measures are judged to be effective. When abnormalities are found in the monitoring data, including a sudden increase in oxygen concentration and a sharp increase in temperature, the fire prevention measures are judged to be ineffective.

[0014] The beneficial effects of the present invention are: 1. In the present invention, a layer of closed flame retardant material is adhered to the polyester fiber net laid on the recovery channel of the working face. After the mining is stopped, the closed net will completely seal the goaf, and at the same time, the upper and lower corners of the working face will be blocked to block the oxygen supply conditions, and the goaf will be isolated and sealed. Then, nitrogen injection, liquid nitrogen or pressurized liquid carbon dioxide is used to reduce the oxygen content in the goaf, and finally the purpose of fire prevention and extinguishing is achieved, ensuring the safe recovery of the working face and protecting the safety of personnel and equipment.

[0015] 2. The present invention only needs to use simple and common materials. Compared with the costs of sealing, unsealing, equipment maintenance, etc. caused by fire, the required material costs and labor costs are relatively low. After implementation, it will help to improve the safety production level of coal mining enterprises, reduce environmental pollution and social impacts caused by fire accidents, and have good social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of a closed goaf area enclosed by a closed net according to the present invention; Figure 2 It is a schematic diagram of the upper and lower corner blocking of the present invention. DETAILED DESCRIPTION

[0017] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with examples. The examples are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0018] Embodiment 1 according to Figure 1 , 2As shown, this embodiment proposes a method for preventing and extinguishing fire during recovery of a mining face, comprising the following steps: S1: Several layers of closed flame retardant material are adhered to the polyester fiber net laid on the working face recovery channel to form a closed net; the closed flame retardant material is a flame retardant cloth or a wind tube cloth, and specifically includes the following steps: on the working face recovery channel, first lay a layer of polyester fiber net, and control the width of the polyester fiber net to horizontally adapt to cover the width of the entire goaf; adhere at least one layer of closed flame retardant material on the polyester fiber net to form a closed net.

[0019] S2: When the mining is stopped, the closed net will completely close the goaf to form a closed oxygen-proof space; specifically, the following steps are included: when the working face is recovered to the stop mining position, the laid closed net is used to cover the goaf to form a closed oxygen-proof space; the closed space is controlled to have no gaps by adding sealing strips and using sealants. After closing, the oxygen concentration in the goaf is continuously monitored. When the oxygen concentration is found to be abnormally high, the closing operation is performed again. At the same time, sufficient fire-fighting equipment is prepared to deal with emergencies.

[0020] S3: Seal the upper and lower corners of the working face to further block the oxygen supply conditions; specifically include the following steps: prepare flame retardant foam glue, sealant and support frame; clean the upper and lower corners to remove debris and coal dust; install the support frame according to the shape and size of the upper and lower corners; lay the flame retardant foam glue on the support frame to ensure that the material completely covers the opening parts of the upper and lower corners; use sealant to fill the gaps between the flame retardant foam glue, and during the filling process, fully penetrate and solidify the sealant to form a sealing layer; after completion, check the sealed area to ensure that there are no missed gaps and openings. The upper and lower corners of the working face goaf refer to the angle between the upper part of the working face and the roof or support during coal mining, which is called the upper corner of the working face, and the angle between the lower part of the working face and the coal bottom or support is called the lower corner of the working face. The upper corner specifically refers to the return air side of the coal mining working face, and the triangular area close to the upper wall of the return air channel and the edge of the goaf. The ventilation conditions in this area are poor and the gas concentration is high.

[0021] S4: Inject inert medium to reduce the oxygen content in the goaf and inhibit spontaneous combustion of coal seams; the injected inert medium includes a mixture of one or more of nitrogen, liquid nitrogen, and liquid carbon dioxide, and specifically includes the following steps: prepare the inert medium and first evaluate the safety status of the goaf, including oxygen concentration, temperature, and coal seam spontaneous combustion tendency indicators; determine the injection point based on the shape and size of the goaf, and select an area with a high risk of coal seam spontaneous combustion; inject the inert medium and evenly distribute the inert medium in the goaf; continuously monitor the oxygen concentration and temperature changes in the goaf, and adjust the number of injection points and the injection speed according to the variables.

[0022] S5: During the sealing and gas injection process, continuously monitor the oxygen concentration and temperature changes in the goaf to evaluate the effectiveness of fire prevention and extinguishing measures. For oxygen concentration, use an oxygen concentration monitor for monitoring; for temperature, use a temperature sensor or infrared thermometer for monitoring. Before monitoring, determine the monitoring point based on the risk area of ​​spontaneous combustion of the coal seam, the characteristics of gas flow, and the coverage of the monitoring equipment. Continuously monitor the oxygen concentration and temperature changes in the goaf. During the monitoring process, record the data regularly and pay attention to the fluctuations in the data. Analyze the trends of the data, the occurrence of abnormal values ​​and the reasons, and evaluate the effectiveness of fire prevention and extinguishing measures. When the oxygen concentration and temperature are kept within the safe range and there is no obvious upward trend, the fire prevention and extinguishing measures are judged to be effective. When abnormalities are found in the monitoring data, including a sudden increase in oxygen concentration and a sharp increase in temperature, the fire prevention measures are judged to be ineffective.

[0023] Embodiment 2 according to Figure 1 , 2 As shown, this embodiment proposes a method for preventing and extinguishing fire during the recovery of the mining working face, including the following: in order to safely recover the working face, careful analysis and continuous exploration were carried out. During the recovery channel of the working face, the support was stopped and the main reason for the fire after the support was that the working face was open, there was a space condition for storing heat and there was a continuous oxygen supply condition. Therefore, through various attempts, it was finally determined that the method of sealing all the goafs, blocking the oxygen supply conditions, and preventing the fire of the working face can ensure the safe recovery of the working face; A layer of closed flame retardant material or wind tube cloth is adhered to the polyester fiber net laid in the recovery channel of the working face. After reaching the stop mining position, the closed net will completely seal the goaf, and at the same time, the upper and lower corners of the working face will be blocked to block the oxygen supply conditions, and then nitrogen, liquid nitrogen or pressurized liquid carbon dioxide will be used to prevent fire and extinguish fire, which can fully ensure the safe recovery of the working face. Through the use of this method, the goaf of the working face can be completely isolated and closed, the oxygen supply conditions can be completely blocked, and nitrogen, liquid nitrogen or liquid carbon dioxide can be used to reduce the oxygen content in the goaf, ultimately achieving the purpose of fire prevention and extinguishing, and ensuring the safe recovery of the working face.

[0024] By using this method, fire can be effectively prevented during the recovery of the working face, ensuring safe recovery of the working face. If the working face is closed due to fire, it will take at least 3 months from the closing to the unsealing. The cost of liquid nitrogen injection, labor costs during the period, and equipment maintenance costs after unsealing are analyzed for benefits: Liquid nitrogen cost (material cost): (tunnel space + working surface space) * 1.2 coefficient / 680 times * unit price [(150*19*2)+(230m*24.5+230*24.5*60%)]*1.2 / 680*2000)=51939 yuan.

[0025] Labor costs: 2 people for ground nitrogen injection, 7 people for two-level lifting and transportation, 2 people for nitrogen injection at the working face, 1 tile inspector and 1 safety inspector. A total of 13 people are needed per shift, 3 shifts a day, a total of 39 people, a total of 117 workers in 3 months, each worker is calculated at 400 yuan, 117*400=46800 yuan.

[0026] Equipment maintenance costs after unsealing: The equipment maintenance in the fire zone is estimated as a major overhaul and calculated at 20% of the original value of the equipment, that is, the original value of the equipment is 100 million * 20% = 20 million yuan.

[0027] Total cost: 51939+46800+20000000=20098739 yuan The cost of additional air duct cloth is 15 yuan / ㎡, 230m working surface, and the mesh width is calculated as 10m, so the total cost is 2300*15=34500 yuan.

[0028] Final benefit: 20098739-34500=20064239 yuan.

[0029] In summary, compared with the costs of sealing, unsealing, equipment maintenance, etc. caused by fire, the material costs and labor costs required by the method of the present invention are relatively low. Taking the above embodiment as an example, after adopting the method of the present invention, it is estimated that the cost can be saved by more than 20 million yuan. It is helpful to improve the safety production level of coal mining enterprises, reduce environmental pollution and social impact caused by fire accidents, and has good social benefits.

[0030] The method for preventing and extinguishing fire during the recovery of the mining face is to adhere a layer of closed flame retardant material on the polyester fiber net laid in the recovery channel of the working face. After reaching the stop mining position, the closed net will completely close the goaf, and at the same time, the upper and lower corners of the working face are blocked to block the oxygen supply conditions, and the isolation is closed. Then, nitrogen injection, liquid nitrogen or pressurized liquid carbon dioxide is used to reduce the oxygen content in the goaf, and finally the purpose of preventing and extinguishing fire is achieved, the safe recovery of the working face is ensured, and the safety of personnel and equipment is guaranteed. Moreover, the present invention only needs to use simple and universal materials, and the required material cost and labor cost are relatively low compared with the costs of closing, unsealing, equipment maintenance, etc. caused by fire. After implementation, it is helpful to improve the safety production level of coal mining enterprises, reduce environmental pollution and social impact caused by fire accidents, and has good social benefits.

[0031] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preventing and extinguishing fire during recovery of a mining face, characterized in that: The following steps are involved: S1: Several layers of closed flame retardant material are adhered to the polyester fiber net laid on the recovery channel of the working surface to form a closed net; S2: When the mining is stopped, the closed net will completely seal the goaf to form a closed oxygen-isolated space; S3: Block the upper and lower corners of the working surface to further block the oxygen supply conditions; S4: Inject inert medium to reduce the oxygen content in the goaf and inhibit spontaneous combustion of coal seams; S5: During the sealing and gas injection process, continuously monitor the oxygen concentration and temperature changes in the goaf to evaluate the effectiveness of fire prevention and extinguishing measures.

2. A method for preventing and extinguishing fire during recovery of a mining face according to claim 1, characterized in that: In S1, the closed flame retardant material is flame retardant cloth or air duct cloth.

3. A method for preventing and extinguishing fire during recovery of a mining face according to claim 2, characterized in that: The S1 comprises the following steps: On the recovery channel of the working face, firstly lay a layer of polyester fiber net, and control the width of the polyester fiber net to horizontally adapt to cover the width of the entire goaf; At least one layer of closed flame retardant material is adhered to the polyester fiber web to form a closed web.

4. A method for preventing and extinguishing fire during recovery of a mining face according to claim 1, characterized in that: The S2 comprises the following steps: When the working face is recovered to the stop-mining position, the laid closed net is used to cover the goaf to form a closed oxygen-isolating space; Control and seal seamless gaps by adding sealing strips and using sealants.

5. A method for preventing and extinguishing fire during recovery of a mining face according to claim 4, characterized in that: In S2, after sealing, the oxygen concentration in the goaf is continuously monitored. When it is found that the oxygen concentration increases abnormally, the sealing operation is performed again. While sealing, sufficient fire-fighting equipment is prepared to deal with emergencies.

6. A method for preventing and extinguishing fire during recovery of a mining face according to claim 1, characterized in that: The S3 comprises the following steps: Prepare flame retardant foam glue, sealant and support frame; Clean the upper and lower corners to remove debris and coal dust; Install the support frame according to the shape and size of the upper and lower corners; Lay the flame retardant foam adhesive on the support frame, making sure the material completely covers the openings in the upper and lower corners; Use sealant to fill the gaps between the flame retardant foam adhesives. During the filling process, the sealant is fully penetrated and cured to form a sealing layer; Once completed, inspect the blocked area to ensure there are no gaps or openings that were missed.

7. A method for preventing and extinguishing fire during recovery of a mining face according to claim 1, characterized in that: In S4, the injected inert medium includes a mixture of one or more of nitrogen, liquid nitrogen, and liquid carbon dioxide.

8. A method for preventing and extinguishing fire during recovery of a mining face according to claim 7, characterized in that: The S4 comprises the following steps: Prepare inert medium and first evaluate the safety status of the goaf, including oxygen concentration, temperature, and coal seam spontaneous combustion tendency indicators; Determine the injection point based on the shape and size of the goaf, and choose an area with a high risk of spontaneous combustion of the coal seam; Inject inert medium and evenly distribute it in the goaf; Continuously monitor the oxygen concentration and temperature changes in the goaf, and adjust the number of injection points and injection speed based on the variables.

9. A method for preventing and extinguishing fire during recovery of a mining face according to claim 1, characterized in that: In S5, the oxygen concentration is monitored by an oxygen concentration monitor; the temperature is monitored by a temperature sensor or an infrared thermometer. Before monitoring, the monitoring point is determined by comprehensively considering the risk area of ​​spontaneous combustion of the coal seam, the characteristics of the gas flow and the coverage of the monitoring equipment.

10. A method for preventing and extinguishing fire during recovery of a mining face according to claim 9, characterized in that: In S5, the oxygen concentration and temperature changes in the goaf are continuously monitored. During the monitoring process, data are recorded regularly, and data fluctuations are noted. The data trends, the occurrence of abnormal values ​​and their causes are analyzed to evaluate the effectiveness of fire prevention and extinguishing measures. When the oxygen concentration and temperature are kept within a safe range and there is no obvious upward trend, the fire prevention and extinguishing measures are judged to be effective. When abnormalities are found in the monitoring data, including a sudden increase in oxygen concentration and a sharp increase in temperature, the fire prevention measures are judged to be ineffective.

Images