A device and method for treating large-area suspended roof at fully-mechanized mining end

Abstract

The application discloses a device and method for treating large-area suspended roof at a fully-mechanized mining end, which comprises the following steps: S1, surveying and measuring the area of the suspended roof area, and designing the size and position scheme of the drilling; S2, drilling according to the design scheme; S3, filling the pre-splitting agent in the drilling; and S4, initiating the pre-splitting, wherein the device comprises at least one group of a plurality of pre-splitting agents arranged according to a certain layout, the pre-splitting agent comprises a fracturing agent A agent and a starter B agent inserted in the A agent, the pre-splitting agents are electrically connected in series, the number of the pre-splitting agents connected in series is less than ten, and multiple groups can be arranged. Through the application and practical experience of the method and device, the fully-mechanized large-area suspended roof treatment technology is improved, the problem of the large suspended roof area at the fully-mechanized mining end is solved, and the device is safe and reliable, simple in construction and practical.

Description

Technical Field

[0001] This invention belongs to the field of coal mining technology, and specifically relates to a device and method for managing large-area roof overhang at the end of fully mechanized mining. Background Technology

[0002] The end of a fully mechanized mining face refers to the point where the working face connects to the track roadway and haulage roadway. A large-area overhang at the end of a fully mechanized mining face refers to an overhang area exceeding 2m x 5m or several times that size. There are two main reasons for overhang formation: First, the working face roof is hard rock with a large thickness and underdeveloped joints and fissures, making it difficult to collapse after coal seam mining, thus forming an overhang. Second, the combined support of the working face supports, protective coal pillars, and the roof anchors of the two roadways acts on the triangular overhangs at both ends, forming a relatively tight unified structure between the immediate roof and the existing roof, increasing the overhang area on the goaf side of the end. When the overhang at the end of a fully mechanized mining face reaches a certain distance, it easily leads to large-area pressure buildup and gas accumulation in the upper and lower corners. If the roof collapses at this point, the accumulated gas and harmful air will surge out instantly, forming a hurricane and shock pressure, seriously threatening the safety of underground workers and equipment. Therefore, large-area overhangs at both ends of a fully mechanized mining face have become a significant technical challenge.

[0003] Currently, there are three main methods for dealing with large-area roof overhangs at the face of fully mechanized mining: anchor removal, deep-hole pre-splitting blasting, and roof fracturing. Roof fracturing is primarily used for hard roofs, and the main fracturing techniques include hydraulic fracturing, pre-splitting blasting, and CO2 fracturing. However, all three techniques have certain drawbacks. Hydraulic fracturing involves using high-pressure water to perform segmented fracturing within a borehole before the working face is mined, thereby disrupting the integrity of the roof. It is widely used to fracturing the roof, but its efficiency is low, its water consumption is high, and its effect is difficult to control, increasing the drainage volume of the working face. Pre-splitting blasting uses explosives to weaken the roof through deep hole pre-blasting, which is the most effective method, but it is costly and has great potential dangers. CO2 fracturing technology uses a high-pressure pump to pre-inject liquid carbon dioxide into a special storage pipe. During use, the current is turned on, and the instantaneous high temperature causes the carbon dioxide in the storage pipe to quickly change from liquid to gas, thereby generating volumetric rock pre-splitting agent pressure that causes the roof to fracture. However, this method is only suitable for roofs with strong integrity and is not universal. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a device and method for managing large-area roof overhangs at the end of fully mechanized mining faces. This invention supplements and improves the technology for managing large-area roof overhangs in fully mechanized mining faces, solves the problem of excessively large roof overhangs at the end of fully mechanized mining faces, and is low in cost and easy to operate.

[0005] The present invention is implemented as follows: a pre-cracking agent, characterized in that it comprises a fracturing agent A and an initiator B that can be inserted into agent A, wherein agent A comprises a cylinder body and a cylinder cap, the cylinder cap being provided with a one-time opening insertion hole matching agent B, and agent A contains a pressure-controlled gas-generating material; agent B is a rod made of ignition material, one end of the rod being provided with a twisted ignition wire.

[0006] Furthermore, the dimensions of agent B are φ10mm×200mm.

[0007] A device for treating large-area overhang at the end of fully mechanized mining operations, comprising the aforementioned pre-fracturing agent, the device comprising at least one set of pre-fracturing agents electrically connected in series and installed in the borehole, the pre-fracturing agent comprising fracturing agent A and initiator B inserted into agent A, wherein the number of pre-fracturing agents connected in series is less than ten.

[0008] Furthermore, Agent A includes a cylinder body and a cylinder cap, with a one-time opening insertion hole on the cylinder cap that matches Agent B. Agent A contains pressure-controlled gas-generating material. Agent B is a rod made of ignition material, with a twisted ignition wire at one end of the rod. One end of the twisted ignition wire is inserted into the inner end of Agent A, and the other end of the twisted ignition wire can be led out of the drill hole during use.

[0009] Furthermore, the pre-splitting agent is arranged as follows: five pre-splitting agents are arranged in a row on the roof of the suspended roof area. The distance between the two boreholes near the edge of the suspended roof area and the edge is 450mm. The spacing between the two pre-splitting agents is 900mm. The spacing between the pre-splitting agents on the side near the protective coal pillar is 800mm. The spacing between the remaining rows is 1600mm. The angle between the pre-splitting agent and the roof is 75°, inclined towards the goaf side.

[0010] Furthermore, Agent A is filled with a pressure-controlled gas-generating material, which is mainly a tetrazolium polymer. The gas produced by the combustion of the tetrazolium polymer is mainly nitrogen, with low smoke, and the smoke is white water vapor mist. It is non-toxic and non-corrosive and will not corrode mining equipment.

[0011] A method for managing large-area overhead roof overhangs at the end of fully mechanized mining operations includes the following steps: S1. Survey and measure the area of ​​the suspended roof area, and design a drilling size and location scheme on the roof plate of the suspended roof area. A reasonable drilling diameter is an important parameter to avoid drilling punching phenomenon. The arrangement of the row spacing can optimize the rock breaking effect of the roof plate. Based on theoretical analysis, laboratory experiments and engineering practice, design drilling parameters. S2, Drill holes according to the design plan; S3, fill the borehole with pre-cracking agent. One end of the twisted pair ignition wire for installing the pre-cracking agent is placed inside the borehole, and the other end of the twisted pair ignition wire is left outside the borehole. After placement, seal the borehole with mud. The pre-cracking agents between different boreholes are arranged in series. The number of pre-cracking agents in a group should be less than ten. Multiple groups can be set according to the actual situation. S4, pre-cracking initiation: A momentary high voltage is applied to the pre-cracking agent to initiate pre-cracking. The starting circuit current is not less than 1A. After pre-cracking, the roof plate is no longer a single piece; a certain number of cracks are generated on the roof plate, and the suspended roof area changes from a whole to zero, dispersing the pressure area and solving the problem of large-area suspended roof. For multiple sets of pre-cracking agents, pre-cracking must be carried out step by step according to the sets.

[0012] Furthermore, the arrangement of the boreholes in S1 is as follows: five boreholes are arranged in a row on the top plate of the suspended roof area, the distance between the two boreholes near the edge of the suspended roof area and the edge is 450mm, the spacing between the two boreholes is 900mm, the row spacing of the boreholes near the protective coal pillar is 800mm, and the spacing of the remaining rows is 1600mm.

[0013] Furthermore, the borehole has a diameter of 50mm, a depth of 10m, and an angle of 75° between the borehole and the roof, inclined to the side of the goaf.

[0014] Furthermore, using the MD200LS type mining digital display detonator, the resistance value of the pre-cracking agent must be digitally measured before and after startup.

[0015] The beneficial effects of this invention are as follows: Through practical experience in applying the method and apparatus of this invention, the technology for managing large-area overhanging roofs in fully mechanized mining has been improved, solving the problem of excessively large overhanging roof areas at the ends of fully mechanized mining faces. The method and apparatus of this invention are safe, reliable, and easy to construct. After intensive drilling and rock pre-splitting treatment, as the working face continues to advance, the roadway roof gradually begins to collapse. With the increase in free face, the collapse rate of the roof accelerates, shortening the overhanging distance compared to the previous method, achieving the expected results. The adoption of the method and apparatus of this invention avoids gas accumulation and large-area roof collapse caused by large-area overhanging roofs, which is of significant practical importance for ensuring safe coal mine production, realizing large-scale continuous high-intensity safe mining in these mines, and improving the level of coal mine production and safety. Furthermore, the method and apparatus of this invention have important guiding significance for safe mining under similar conditions, and are therefore of practical importance.

[0016] The present invention will now be further explained with reference to the accompanying drawings. Attached Figure Description

[0017] Figure 1 This is a schematic diagram showing the location of the suspended area in this invention; Figure 2 This is a top view schematic diagram of the drilling and pre-cracking agent arrangement scheme in the suspended area of ​​the present invention; Figure 3 This is a side view schematic diagram of the drilling and pre-cracking agent arrangement scheme in the suspended area of ​​the present invention; Figure 4 This is a schematic diagram of the structure of pre-cracking agent A of the present invention; Figure 5 This is a schematic diagram of the structure of the pre-cracking agent B of the present invention; Figure 6 This is a schematic diagram of the assembly of pre-cracking agents A and B of the present invention; Figure 7 This is a schematic diagram of the pre-cracking agent installed inside the borehole according to the present invention. Detailed Implementation

[0018] A pre-cracking agent, such as Figures 3 to 6 As shown, it includes fracturing agent A 31 and initiator B 32 that can be inserted into agent A. Agent A 31 includes a cylinder body 311 and a cylinder cover 312. The cylinder cover 312 is provided with a one-time opening insertion hole 313 that matches agent B 32. Agent A 31 contains pressure-controlled gas-generating material. Agent B 32 is a rod 321 made of ignition material. One end of the rod 321 is provided with a twisted ignition wire 322.

[0019] The B agent 31 has a specification size of φ10mm×200mm, and the A agent can be in various specifications: φ30mm×300mm, φ41mm×400mm, φ50mm×900mm and φ76mm×900mm.

[0020] The device includes at least one set of pre-cracking agents 3 electrically connected in series and installed in the borehole 2. The pre-cracking agents 3 include fracturing agent A 31 and initiator B 32 inserted in agent A 31. The number of pre-cracking agents 3 connected in series is less than ten. According to experiments and experience, the number of pre-cracking agents 3 connected in series should not be too many, preferably not more than ten. Detonating too many at once will cause large-area pre-cracking and result in a suspended ceiling problem.

[0021] The A agent 31 includes a cylinder body 311 and a cylinder cover 312. The cylinder cover 312 is provided with a one-time opening and use insertion hole 313 that matches the B agent 32. The A agent 31 contains a pressure-controlled gas-generating material. The B agent 32 is a rod 321 made of ignition material. One end of the rod 321 is provided with a twisted ignition wire 322. One end of the twisted ignition wire 322 is inserted into the inner end of the A agent 31. When in use, the other end of the twisted ignition wire 322 can be led out of the drill hole.

[0022] The pre-splitting agent 3 is arranged as follows: five pre-splitting agents 3 are arranged in a row on the roof plate 4 of the suspended roof area 1. The distance 21 between the two boreholes near the edge of the suspended roof area 1 and the edge is 450mm. The spacing 22 between the two pre-splitting agents 3 is 900mm. The spacing 23 between the pre-splitting agents 3 on the side near the protective coal pillar 5 is 800mm. The spacing 24 between the remaining pre-splitting agents 3 is 1600mm. The angle 25 between the pre-splitting agents 3 and the roof plate 4 is 75°, and they tend to the side of the goaf 6.

[0023] The pressure-controlled gas-generating material filled in Agent A 31 is mainly composed of tetrazolium polymer. The gas produced after the tetrazolium polymer is burned is mainly nitrogen, with low smoke and white water vapor mist. It is non-toxic and non-corrosive and will not corrode mining equipment.

[0024] A method including a device for managing large-area overhead roof overhangs at the end of fully mechanized mining operations, such as... Figures 1 to 7 As shown, it includes the following steps: S1. Survey and measure the area of ​​the suspended roof area 1, design the size and location of borehole 2, and a reasonable borehole diameter is an important parameter to avoid borehole punching. The arrangement of the row spacing can optimize the rock breaking effect of the roof 4. Based on theoretical analysis, laboratory experiments and engineering practice, design the borehole parameters. S2, Drill holes according to the design plan; S3, fill the borehole with pre-cracking agent 3. One end of the installation twin-twisted ignition wire of the pre-cracking agent 3 is placed inside the borehole, and the other end of the twin-twisted ignition wire is left outside the borehole. After being placed, seal the borehole with mud 7. The pre-cracking agents between different boreholes are arranged in series. The number of pre-cracking agents in a group should be less than 10. Multiple groups can be set according to the actual situation. S4, pre-cracking initiation: A momentary high voltage is applied to the pre-cracking agent, and the pre-cracking is initiated using an initiator. The starting circuit current is not less than 1A. After pre-cracking, the roof plate is no longer a single piece; a certain number of cracks are generated on the roof plate, and the suspended roof area changes from a whole to zero, dispersing the pressure area and solving the problem of large-area suspended roof. For multiple sets of pre-cracking agents, pre-cracking must be carried out step by step according to the sets.

[0025] The arrangement of the boreholes 2 is as follows: five boreholes 2 are arranged in a row on the roof plate 4 of the suspended roof area 1. The distance 21 between the two boreholes 2 closest to the edge of the suspended roof area 1 and the edge is 450mm. The spacing 22 between the two boreholes is 900mm. The row spacing 23 of the boreholes on the side closest to the protective coal pillar 5 is 800mm. The remaining row spacing 24 is 1600mm.

[0026] Furthermore, the borehole 2 has a diameter of 50mm, a depth of 10m, and an angle of 25° between the borehole 2 and the roof 4 is 75°, inclined to one side of the goaf 6.

[0027] Furthermore, the detonator is an MD200LS type mining digital display detonator, and the resistance value of the pre-splitting agent 3 must be digitally measured before and after activation.

Claims

1. A method for managing large-area overhead roof overhangs at the end of fully mechanized mining operations, characterized in that: The following device is used: Includes at least one set of pre-cracking agents (3) electrically connected in series and installed in the borehole (2), the pre-cracking agents (3) including agent A (31) and agent B (32) inserted in agent A (31); the number of pre-cracking agents (3) connected in series is less than ten; The A agent (31) includes a cylinder body (311) and a cylinder cover (312). The cylinder cover (312) is provided with a one-time opening and use socket (313) that matches the B agent (32). The A agent (31) contains a pressure-controlled gas-generating material, tetrazolium polymer. The B agent (32) is a rod (321) made of ignition material. One end of the rod (321) is provided with a twisted ignition wire (322). One end of the twisted ignition wire (322) is inserted into the inner end of the A agent (31). When in use, the other end of the twisted ignition wire (322) can be led out of the drill hole. The steps are as follows: S1, survey and measure the area of ​​the suspended roof area (1), design the size and location of the boreholes (2) on the roof plate (4) of the suspended roof area (1), the arrangement of the boreholes (2) in S1 is as follows: five boreholes (2) are arranged in a row on the roof plate (4) of the suspended roof area (1), the distance (21) between the two boreholes (2) near the edge of the suspended roof area (1) and the edge is 450mm, the spacing (22) between the two boreholes is 900mm, the row spacing (23) of the boreholes near the protective coal pillar (5) is 800mm, the row spacing (24) of the remaining boreholes is 1600mm, the angle (25) between the boreholes (2) and the roof plate (4) is 75°, and they tend to the side of the goaf area (6); S2, Drilling is carried out according to the design plan. The diameter of the hole (2) is 50mm and the depth is 10m. S3, fill the borehole with pre-cracking agent (3), one end of the installation twin ignition wire of the pre-cracking agent (3) is placed into the inner end of the borehole, and the other end of the twin ignition wire is left outside the borehole. After being placed in, seal the borehole with mud (7). The pre-cracking agents between different boreholes are arranged in series. The number of pre-cracking agents in a group should be less than ten. Multiple groups can be set according to the actual situation. S4, detonate pre-crack, pass instantaneous high voltage to the pre-cracking agent (3) to start pre-crack, the starting circuit current is not less than 1A, the top plate after pre-crack is no longer a whole plate, a certain number of cracks are generated on the top plate, the suspended area changes from whole to zero, the pressure area is dispersed, and the problem of large area suspended is solved; for those with multiple sets of pre-cracking agents, pre-cracking must be carried out step by step according to the sets.

2. The method for addressing large-area overhead roof overhangs at the end of fully mechanized mining operations according to claim 1, characterized in that, Using the MD200LS type mine digital display detonator, the resistance value of the pre-cracking agent (3) must be measured digitally before and after starting.

3. The method for addressing large-area overhead roof overhangs at the end of fully mechanized mining operations according to claim 1, characterized in that, The dimensions of Agent B (32) are φ10mm×200mm.

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