Disaster management methods for mining of extremely thin coal seam protective seams

Abstract

The present invention belongs to the technical field of coal mining, and particularly provides a disaster management method for mining of a protective layer of an extremely thin coal seam, mainly including the installation of an interlayer borehole, a total negative pressure ventilation measure and a gas prevention measure of a mining strip, and further including a gob side entry earth retaining process, a gas venting measure at the excavation site, a monitoring and control measure, a fire prevention and extinguishing measure at the excavation strip and a dust prevention measure at the mining strip. In this method, a high-pressure nitrogen injection device is used to carry out a pressurized nitrogen injection measure from the header of a boom-type coal miner into the mining strip, so as to ensure that the gas components in the header are mainly nitrogen and gas, and not only carry out normal gas prevention in the mining strip, but also carry out gas venting in the excavation strip by an interlayer borehole, respectively install multi-parameter monitoring probes at the opening of the mining strip, the end of the gob side entry earth retaining, the extraction pipe of the excavation strip and the closed observation hole at the excavation site, and add a dust monitoring probe at the opening of the mining strip.

Description

[Technical field]

[0001] The present invention belongs to the technical field of coal mining, and in particular provides a disaster management method for mining of extremely thin coal seam protection layer. [Background technology]

[0002] In terms of industrial production, China relies mainly on coal as its energy source, and among the coal seams extracted through underground mining operations, those less than 1.3m thick are called thin coal seams, while those less than 0.9m thick are often called ultra-thin coal seams.

[0003] Although the mining technology of thin coal seams is becoming more and more mature, the mining methods of ultra-thin coal seam protection layers are still in the exploration stage. With the continuous improvement of mining methods, the corresponding mining disaster management measures of ultra-thin coal seam protection layers are also adjusted accordingly. For the mining work of ultra-thin coal seam protection layers, a boom-type mining process (a dual mining strip alternate construction method deployed around a boom-type coal miner) has been developed.

[0004] At present, the disaster management for the mining means of the extremely thin coal seam protection layer still has the following problems:

[0005] When the coal miner excavates the face, the miner's excavation drum excavates and drops the coal, and then the gas is desorbed from the dropped coal, and the gas also comes out from the coal wall and roof floor into the strip space. When the miner drum excavates and drops the coal, sparks may occur, which may cause a gas explosion or combustion.

[0006] Using only local ventilation equipment to supply air into the mining strip to dilute and exhaust the gas makes it difficult for the amount of air to meet the demand, and when a large amount of air enters the mining strip, accidents such as gas combustion, gas explosions and coal dust explosions are more likely to occur. Regarding gas in the mined strip, the strip mined by the boom-type coal miner is a relatively sealed space, and a large amount of gas is desorbed and released from the strip hole. In particular, after these narrow safety coal pillars (about 0.5 m) enter the mined area, they are affected by the rock behavior of the mined area and are crushed, releasing a certain amount of gas desorbed from the coal pillars.

[0007] In addition, when the mining strip is released from the protected layer, a large amount of gas is released from the protected layer and enters the excavation site where the protected layer was mined through interlayer cracks.

[0008] Furthermore, under the influence of rock behavior, the crushed safety coal pillars in the excavation area may be oxidized and heat may accumulate and spontaneously combust under the action of long-term gas venting. Therefore, it is necessary to carefully monitor the changes in the gas composition in the excavation area and strictly control the amount of gas venting in the excavation area. After meeting the basic requirements of mining out the protective layer and venting the pressure-relieving gas, it is necessary to take appropriate measures to inject nitrogen into the excavation area.

[0009] During the advancement of the excavation part of the coal mining machine, the internal space of the mining strip gradually becomes larger as the advancement work progresses. Considering factors such as high dust concentration in the mining strip hole, high gas emission, and high spatial humidity, the means of using a conventional random tracking monitoring probe cannot meet the operating environment requirements of various monitoring sensors. Summary of the Invention [Problem to be solved by the invention]

[0010] To solve the above problems, the present invention provides a disaster management method for mining of extremely thin coal seam protection layer. [Means for solving the problem]

[0011] In order to achieve the above objectives, the technical solution used in the present invention is a disaster management method for mining the protective layer of extremely thin coal seams, including the installation of interlayer boreholes, total negative pressure ventilation measures and gas prevention measures for mining strips; The installation of interlayer boreholes is specifically performed as follows: Before stopping the face, in the rock mass above the mining wall layer of the face transport gateway tunnel, a borehole is constructed in the coal seam roof rock mass at a position directly above the center of the opening of the mining strip; Specifically, the total negative pressure ventilation measures are as follows: The ventilation system in the mining work space of the coal face is a total negative pressure ventilation system, and the main intake and return route is from the face transport gateway tunnel → gob side entry retaining tunnel → preparation face open offcut → preparation face transport gateway tunnel. The gas prevention measures for mining strips are specifically as follows: Nitrogen injection measures are carried out in the mining strip using a high-pressure nitrogen injection device, The interlayer borehole is connected to the withdrawal pipe, and the interlayer borehole isolates the gas to be withdrawn and the inert gas in the strip.

[0012] Further, the method further includes a gob-side entry retaining process, The gob side entry soil retaining process is specifically as follows: A sealing pocket is pre-filled at the opening of the drilling strip, and the pocket is filled by injecting gas and then grouting to seal the opening of the drilling strip. After grouting is completed, the covering is laid and the covering is reinforced by combining the stainless steel belt with the bolts that were embedded in advance during the coal mining process. Gunite is applied to the outside of the coating to form a permanent sealing layer. The aim of this paper is to reinforce the tunnel roof using a large deformation anchor cable with constant resistance.

[0013] Additionally, the covering is constructed from a double layer of rebar mesh and a high strength glass fiber reinforced polyester fabric intermediate layer.

[0014] In addition, it also includes measures to vent gas from the excavation site. Specifically, the gas venting measures for the excavated area are as follows: The entrance to the upper tunnel is quickly sealed by grouting to form a closed gas vent tunnel. A large-diameter vent hole is provided in the sealing wall in advance, and is connected to a low negative pressure gas vent system.

[0015] In addition, it includes monitoring and control measures, The monitoring and control measures are specifically: Install a multi-parameter monitoring probe and a dust monitoring probe on the downwind side of the opening of the mining strip; A multi-parameter monitoring probe is installed at the end of the gob side entry retaining wall. Install a monitoring probe in the extraction strip piping. A sealed observation hole is reserved in the grouted sealed section of the excavation site, and a multi-parameter monitoring probe is installed in the observation hole.

[0016] In addition, it further includes fire prevention and extinguishing measures for the mining strip, Fire prevention and extinguishing measures for the mining strip are as follows: During the recovery process, the boom miner header and boom box use the boom miner header spray system to spray inhibitors into the strip. At the same time, monitoring data for the gas vented within the drilling strip is continuously analyzed, and when the data indicators exceed the warning value for spontaneous combustion, nitrogen is injected into the sealed drilling strip using an interlayer borehole.

[0017] In addition, the mining strip is dustproof. Specifically, the dust prevention measures for the mining strip are as follows: The spraying system of the boom type coal miner is used to spray water and perform the primary dust drop. Using interlayer boreholes to change the airflow direction within the mining strip and take secondary dust suppression measures; Install a dust-proof spray device at the opening of the mining strip, and perform dust dropping treatment for the opening of the mining strip; A cleaning and dust removal curtain device is installed in the transportation gateway tunnel of the preparation face to perform cleaning and dust removal. Effect of the Invention

[0018] The beneficial effects of the present invention are as follows:

[0019] In this method, a high-pressure nitrogen injection device is used to carry out pressurized nitrogen injection measures from the header of a boom-type coal mining machine into the mining strip, and the nitrogen injection method of injecting while mining effectively ensures that the gas components in the header are mainly nitrogen and gas, and the oxygen content is extremely low, which cannot meet the conditions for gas explosion or gas combustion.

[0020] This method not only implements general gas prevention within the mining strip, but also degasss the mined strip using an interlayer borehole, and the degassing operation is performed with the strip as the smallest unit, which is advantageous in improving the accuracy of degassing control.

[0021] In this method, multi-parameter monitoring probes are installed at the opening of the mining strip, the end of the gob side entry retaining wall, the extraction pipe of the mining strip, and the sealed observation hole at the mining site, and a dust monitoring probe is added at the opening of the mining strip, which eliminates the monitoring defects of the random tracking monitoring probe and is advantageous to more accurately monitor the changes in gas components in each strip, and provides data support for subsequent gas prevention and fire and dust prevention measures.

[0022] During the recovery process of the boom coal miner's header and boom box, the header spraying system sprays the inhibitor while recovering, effectively solving the problem that the residual coal continues to be oxidized in the strip during the recovery period and may cause spontaneous combustion. [Brief description of the drawings]

[0023] [Figure 1] FIG. 2 is a plan view of the overall layout of the present invention. [Diagram 2] FIG. 2 is an enlarged view of part a in FIG. [Diagram 3] FIG. 2 is a schematic diagram of a radial cross section of the face transportation gateway tunnel of the present invention. [Figure 4] FIG. 2 is a schematic diagram showing the relationship between the drilling strip, pocket, interlayer borehole and withdrawal pipe of the rise face of the present invention. [Diagram 5] FIG. 2 is a schematic diagram showing the relationship between the horizontal face drilling strip, pockets, interlayer boreholes and extraction piping of the present invention. [Figure 6] FIG. 2 is a schematic diagram of the tunnel wall reinforcement structure of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The present invention will now be described in detail with reference to the drawings.

[0025] As shown in Figures 1 to 6, it is applied to the boom-type coal mining process of mining the protective layer of extremely thin coal seams. Specifically, A boom-type coal miner (consisting of two front drive coal miners and a boom box) is used as the coal mining device to perform propulsion type coal mining in an extremely thin coal seam, with mining strips 9 as the smallest construction unit, each strip being parallel to each other; After one coal mining machine is used to complete the mining work of one mining strip 9, another coal mining machine is used to work on the adjacent coal body, and another new mining strip 9 is started. As the excavation work of the new mining strip 9 progresses, the boom box is synchronously retrieved from the previous mining strip 9, and the retrieved boom box is directly transferred to the coal mining machine in the new mining strip, thereby realizing a mining means of the protective layer of the extremely thin coal seam by alternately constructing dual mining strips 9.

[0026] In the coal seam and the adjacent rock layer a, a face transport gateway tunnel 1 (a tunnel in which excavation work is currently being carried out) and a preparatory face transport gateway tunnel 6 (a tunnel for the next excavation work to be carried out after the current face excavation work is completed, and the excavation route is usually parallel to the face transport gateway tunnel 1) are excavated, and a preparatory face open offcut 5 is excavated at the preparatory face 3, and the face transport gateway tunnel 1 and the preparatory face transport gateway tunnel 6 are connected, and the preparatory face open offcut 5 is at the starting position of the entry tunnel direction of the preparatory face 3, While the boom type coal miner is performing excavation work at the face 2 and passing through, the strip-shaped space that the boom type coal miner is advancing is the mining strip 9, the strip-shaped space that the boom type coal miner is recovering is the recovery strip 8, and the strip that remains after the boom type coal miner is removed is the mining strip 7; The boom-type coal miner is equipped with two mining drilling headers, which are located in the recovery strip 8 and the mining strip 9, respectively. The two drilling headers are driven alternately to realize the alternate construction of the dual mining strips. A gob-side entry earth-retaining process is performed on the tunnel where coal mining work has been completed at the face 2 to form a gob-side entry earth-retaining tunnel 4. When planning coal mining, a terminal line 20 (which reserves supporting coal bodies between the entrance of the tunnel and the excavation head 11) is set in advance, and when the area within the terminal line 20 at the face 2 is completely covered by the excavation strip 7, the face 2 becomes the excavation head 11.

[0027] A disaster management method for mining of extremely thin coal seam protection layer, mainly including the installation of interlayer boreholes, total negative pressure ventilation measures, gob side entry soil retaining process, fire prevention and extinguishing measures, dust prevention measures, monitoring and control measures, gas prevention measures in mining strips and gas venting measures in excavation area; The installation of interlayer boreholes is specifically performed as follows: Before stopping the face 2, in the rock mass a above the mining wall layer of the face transport gateway tunnel 1, one interlayer borehole 13 located in the coal seam roof rock mass a is constructed at a position directly above the center of the opening of the mining strip 9, and the construction equipment is a normal mining drill; The interlayer borehole 13 is perpendicular to the mining wall (when the face 2 is the rise plane shown in Figure 4, the borehole can be extended directly into the strip; when the face 2 is the horizontal plane shown in Figure 5, the middle and rear parts of the borehole need to be deflected to ensure that the borehole can be extended accurately into the strip), with a diameter of φ300mm and an end position 5-6m from the strip mouth. A hole wall protection tube is placed in the interlayer borehole 13, and the hole wall protection tube and rock a are fixed by the pressurized grouting method of "sealing both ends and then injecting".

[0028] Specifically, the total negative pressure ventilation measures are as follows: The ventilation system in the mining working space of the coal face is a total negative pressure ventilation system, and the main intake and return route is the face conveying gateway tunnel 1 → gob side entry retaining tunnel 4 → preparation face open offcut 5 → preparation face conveying gateway tunnel 6, and the route of the ventilation system meets the basic requirements of a "U"-shaped total negative pressure ventilation system.

[0029] The gas prevention measures for mining strips are specifically as follows: A high-pressure nitrogen injection device is used to inject nitrogen into the mining strip 9, and the nitrogen injection method is to inject while mining. The outlet of the nitrogen injection device is fixed to the header of the boom-type coal mining machine, and the pressurized nitrogen injection method is used to ensure that the gas components at the front end of the strip during the strip mining period are mainly nitrogen and gas, and the oxygen content is extremely low, which cannot meet the conditions for gas explosion and gas combustion; The interlayer borehole 13 is connected to the withdrawal pipe 12 and serves to isolate the gas to be withdrawn in the strip and the inert gas, thereby avoiding their release into the transport gateway tunnel 1 at the face.

[0030] The gob side entry soil retaining process is specifically as follows: A sealing pocket 14 is pre-embedded in the opening of the drilling strip 7, and a gas injection pipe 15 and a grouting pipe 16 are connected to the pocket 14; Using an air pump to inject gas into the pocket 14 through the gas injection pipe 15 ensures that the pocket 14 is formed in the strip, and avoids the pocket 14 from being wrinkled during grouting, which would affect the sealing effect of the excavation strip 7; A grouting pump is used to grout the pocket 14 through the grouting pipe 16, the slurry material is an inorganic high moisture material, when the pressure of the grouting pump reaches 2.5 MPa and the slurry cannot be injected, the grouting is stopped and the gas injection pipe 15 and the grouting pipe 16 are closed; After the grouting is completed, the covering 18 is laid, and there is a reinforcing metal net on the tunnel wall. Before the coal mining operation, the metal net is sheared in advance to form a strip opening, and the covering 18 is inserted into the metal net along the opening. Furthermore, the covering 18 is reinforced by combining the stainless steel belt 19 with the bolt 17 that was embedded in advance during the coal mining process, and the side of the outer wall of the pocket 14 close to the covering 18 is fixed and connected to the covering 18 by a hanging binding method. In the area where the butt joint work between the interlayer borehole 13 and the extraction pipe 12 is completed, gunite construction is carried out on the outside of the coating 18 to form a permanently closed layer. Considering the problem that the fastness of the bond between the coating 18 and the gunite layer is low, separation or cracks are likely to occur if it is compressed and deformed after that, it is necessary to carry out local re-gunite in the area where cracks have occurred; By using a deformed anchor cable with a large constant resistance to reinforce the tunnel roof and prevent the roof from sinking, the retained tunnel wall rock can maximize its own support function, reducing the deformation of the tunnel and ensuring the effect of retaining soil for gob side entry. The gunite material is preferably an inorganic material or a polymeric material with a low calorific value. Preferably, the covering 18 is constructed from double rebar mesh and a high strength fiberglass reinforced polyester fabric interlayer.

[0031] Specifically, the measures to vent gas from drilling sites are as follows: The entrance of the upper tunnel is quickly sealed by grouting to form a closed gas vent tunnel 10, a large-diameter drain hole is pre-drilled in the sealing wall, a hole wall protection pipe is embedded in the drain hole, and the drain hole is connected to a low-negative pressure gas vent system to realize gas venting in the excavation 11. Before the face 2 is completely excavated, a collapse phenomenon occurs in the excavation strip 7 of the face 2, and under the action of the low negative pressure of the gas venting tunnel 10, some of the gas released when the excavation strip 7 collapses is precipitated in the gas venting tunnel 10.

[0032] The monitoring and control measures are specifically: A multi-parameter monitoring probe (used to monitor gas components such as gas, oxygen, and carbon monoxide) and a dust monitoring probe are installed at a position 5 m from the downwind side of the opening of the mining strip 9 (i.e., the downstream side of the airflow circulation direction in FIG. 1), and the gas component indicators and dust indicators in the worker's working space are mainly monitored; A multi-parameter monitoring probe is installed at the end of the gob side entry retaining wall to monitor the gas component indexes of the return airflow. A multi-parameter monitoring probe is installed in the drain pipe 12 of the drilling strip 7 to monitor each gas component index of the gas in the drilling strip 7; A sealed observation hole (a sealed observation hole is a small hole opened in the sealing wall, and is sealed by grouting after embedding a multi-parameter monitoring probe) is reserved in the grouting sealing part of the excavation 11, and a multi-parameter monitoring probe is installed in the observation hole to monitor each gas component index in the excavation; By installing the above multi-parameter monitoring probe, monitoring and control of gas in the mining strip 9 and in the mining hole 11 is realized.

[0033] Fire prevention and extinguishing measures for the mining strip are as follows: Considering that there is a certain amount of residual coal during the period when the coal miner collects in the mining strip 9, and that if the residual coal is left in the strip for a long period of time, it will oxidize and there is a risk of spontaneous combustion; During the recovery process of the boom miner's header and boom box, the spraying system of the boom miner's header is used to spray inhibitors (used to prevent coal from oxidizing and spontaneously combusting, the main component being antioxidants such as magnesium chloride) into the strip, At the same time, monitoring data for the gas vented within the drilling strip 7 continues to be analyzed, and when the data indicators exceed the warning value for spontaneous combustion, nitrogen is injected into the sealed drilling strip 7 using the interlayer borehole 13.

[0034] Specifically, the dust prevention measures for the mining strip are as follows: Considering that when using the boom-type coal mining process for mining, dust mainly occurs in the mining strip 9 hole, dust prevention is realized by drilling dust suppression measures, which are specifically as follows:

[0035] The spraying system of the boom type coal miner is used to spray water and perform the primary dust drop. Using interlayer boreholes 13 to change the airflow direction within the mining strip 9 and provide secondary dust suppression measures; Install a dustproof spray device at the opening of the mining strip 9, and perform dust dropping treatment on the opening of the mining strip 9; A cleaning and dust removal curtain device is installed in the transportation gateway tunnel 6 of the preparation face, and cleaning and dust removal are performed.

[0036] The above is merely a preferred embodiment of the present invention. Those skilled in the art can make various modifications to the specific embodiments and scope of application based on the concept of the present invention. As long as these modifications do not deviate from the idea of ​​the present invention, they fall within the scope of protection of the present invention. [Explanation of symbols]

[0037] a Rock, 1. Transport gateway tunnel at the face, 2. Face, 3. Preparation face, 4. Gobside entry retaining tunnel, 5. Open offcut at the preparation face, 6. Transport gateway tunnel at the preparation face, 7. Mining strip, 8. Recovery strip, 9. Mining strip, 10. Gas venting tunnel, 11. Drilled area, 12. Vent pipe, 13. Interlayer borehole, 14. Pocket, 15. Gas injection pipe, 16. Grouting pipe, 17. Bolt, 18. Covering, 19. Stainless steel belt, 20. Terminal line

Claims

1. A disaster management method for mining a protective layer of an extremely thin coal seam, which is applied to a boom-type coal mining process for mining a protective layer of an extremely thin coal seam, The boom-type coal mining process for mining the protective layer of extremely thin coal seams specifically includes: A boom-type coal miner is used as the mining device to carry out thrust mining on extremely thin coal seams, with a mining strip as the smallest construction unit, and each strip is parallel to each other; After one mining machine is used to complete the mining work of one mining strip, another mining machine is used to work on the adjacent coal body, and another new mining strip is started. With the advancement of the excavation work of the new mining strip, the boom box is synchronously retrieved from the previous mining strip, and the retrieved boom box is directly transferred to the coal miner in the new mining strip, thereby realizing the mining method of the protection layer of the ultra-thin coal seam of alternately constructing dual mining strips; A disaster management method for mining a very thin coal seam protection layer, including the installation of interlayer boreholes, total negative pressure ventilation measures and gas prevention measures for mining strips, The installation of interlayer boreholes is specifically performed as follows: Before stopping the face, in the rock mass above the mining wall layer of the face transport gateway tunnel, a borehole is constructed in the coal seam roof rock mass at a position directly above the center of the opening of the mining strip; Specifically, the total negative pressure ventilation measures are as follows: The ventilation system in the mining work space of the coal face is a total negative pressure ventilation system, and the main intake and return route is from the face transport gateway tunnel → gob side entry retaining tunnel → preparation face open offcut → preparation face transport gateway tunnel. The gas prevention measures for mining strips are specifically as follows: Nitrogen injection measures are carried out in the mining strip using a high-pressure nitrogen injection device, A disaster management method for mining a protective layer of an extremely thin coal seam, characterized in that the interlayer borehole is connected to a withdrawal pipe, and the gas to be withdrawn and the inert gas in the strip are blocked by the interlayer borehole.

2. Further comprising a gob side entry retaining process; The gob side entry soil retaining process is specifically as follows: A sealing pocket is pre-buried at the opening of the drilling strip, and the pocket is filled by injecting gas and then grouting to seal the opening of the drilling strip. After grouting is completed, the covering is laid and the covering is reinforced by combining the stainless steel belt with the bolts that were embedded in advance during the coal mining process. There is a reinforcing metal mesh on the tunnel wall of the tunnel, and before the coal mining operation, the metal mesh is sheared in advance to form an opening for the strip, and the coating is inserted into the metal mesh along the opening; Gunite is applied to the outside of the coating to form a permanent sealing layer. The method for disaster management in mining of extremely thin coal seam protective layer as claimed in claim 1, characterized in that the method is to reinforce the tunnel roof using a constant resistance large deformation anchor cable.

3. The method for disaster management in mining of extremely thin coal seam protective layer as claimed in claim 2, characterized in that the covering is composed of a double layer of rebar net and an intermediate layer of high strength glass fiber reinforced polyester fabric.

4. Further includes measures to vent gas from drilling sites. Specifically, the measures to vent gas from drilling sites are as follows: The entrance to the upper tunnel is quickly sealed by grouting to form a closed gas vent tunnel. The method for disaster management in mining of a protective layer of an extremely thin coal seam according to claim 1, characterized in that a large-diameter vent hole is provided in advance in the sealing wall, and the hole is connected to a low negative pressure gas vent system.

5. Further including monitoring and control measures, Specifically, the monitoring and control measures are as follows: Install a multi-parameter monitoring probe and a dust monitoring probe on the downwind side of the opening of the mining strip; A multi-parameter monitoring probe is installed at the end of the gob side entry retaining wall. Install a monitoring probe in the extraction strip piping. The method for managing disasters in mining protective layers of extremely thin coal seams as claimed in claim 1, characterized in that a sealed observation hole is reserved in the grouting sealing part of the excavation site, and a multi-parameter monitoring probe is installed in the observation hole.

6. Further including fire prevention and extinguishing measures for drilling strips; Fire prevention and extinguishing measures for the mining strip are as follows: During the recovery process, the boom miner header and boom box use the boom miner header spray system to spray inhibitors into the strip. At the same time, the method for disaster management in mining of the protective layer of an extremely thin coal seam, as described in claim 1, further comprises: continuously analyzing the monitoring data for the gas extracted in the mining strip; and when the data indicator exceeds the warning value of spontaneous combustion, using an interlayer borehole to inject nitrogen into the sealed mining strip.

7. Further including dust prevention measures for mining strips; Specifically, the dust prevention measures for the mining strip are as follows: The spraying system of the boom type coal miner is used to spray water and perform the primary dust drop. Using interlayer boreholes to change the airflow direction within the mining strip and take secondary dust suppression measures; Install a dust-proof spray device at the opening of the mining strip, and perform dust dropping treatment for the opening of the mining strip; The disaster management method for mining a protective layer of an extremely thin coal seam according to claim 1, characterized in that a cleaning and dust-removing curtain device is installed in the transportation gateway tunnel of the preparation face to perform cleaning and dust removal.

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