Fully mechanized caving mining method for steeply-inclined super-thick coal seam

Abstract

The invention discloses a fully-mechanized caving mining method for a steeply-inclined super-thick coal seam, and belongs to the technical field of mining of the steeply-inclined super-thick coal seam. A working face is arranged in the steeply-inclined super-thick coal seam according to inclined long-wall mining, an air inlet rail inclined roadway and a return air transportation inclined roadway are constructed on the two sides of the working face respectively, an open-off cut is constructed along a coal seam bottom plate, and a slope for conveying coal is constructed between the end of the return air transportation inclined roadway and one end of the open-off cut; tunneling from the end of an air inlet track inclined roadway to a coal seam floor and connecting with the other end of the open-off cut to form a connection roadway; in the stoping process, undercutting is synchronously carried out on the slope, the entering connection roadway and working face stoping, a working face goaf naturally collapses, and only the goaf above the slope and the entering connection roadway is filled and supported along with mining; and the hydraulic support moves under pressure, so that mining of the whole working face is completed. The method is simple in step and convenient to use, and safe, efficient and high-recovery-rate stoping can be effectively carried out on the steeply-inclined super-thick coal seam.

Description

Technical Field

[0001] This invention relates to a fully mechanized longwall mining method for steeply inclined extra-thick coal seams, belonging to the technical field of steeply inclined extra-thick coal seam mining, especially for fully mechanized longwall mining of extra-thick coal seams with a dip angle of about 45° and a thickness of less than 20.0m. Background Technology

[0002] Currently, the main methods used for mining thick coal seams include layered mining, high-extraction fully mechanized mining, and fully mechanized top-coal caving mining. Layered mining has the advantage of low equipment cost, but low mining efficiency and high maintenance costs; only horizontal segmented top-coal caving mining is still in use. High-extraction fully mechanized mining has the advantages of a large working space and short production cycle, but the increased mining height leads to poor stability of the surrounding rock under the supports, resulting in significant limitations, especially unsuitable for conditions with large coal seam dip angles. Fully mechanized top-coal caving mining has many advantages, including high mechanization, high output and efficiency, low roadway excavation rate, and low cost per ton of coal. It also has strong adaptability to complex coal seam geological conditions and is currently the most widely used mining method for thick coal seams in my country.

[0003] The coal seam dip angle is one of the key factors restricting the effectiveness of longwall top coal caving. Currently, for extra-thick coal seams with dip angles less than 12°, strike-longwall longwall top coal caving or inclined longwall longwall top coal caving methods can be used for mining. For extra-thick coal seams with dip angles greater than 12°, strike-longwall longwall top coal caving is used. When the coal seam thickness is greater than 20.0 m and the dip angle is greater than 50°, horizontal segmented top coal caving becomes the optimal method. For strike-longwall longwall top coal caving, when the coal seam dip angle is greater than 25°, the stability of the surrounding rock of the working face supports becomes poor, and top coal recovery becomes difficult. For extra-thick coal seams with dip angles greater than 35°, the working efficiency drops sharply, and the output is generally 1 / 10 to 1 / 5 of that under gently inclined conditions. For extra-thick coal seams with a dip angle of around 45° and a thickness of less than 20.0m, since there is no better method, we have been trying to improve the top coal recovery effect and production efficiency of longwall longwall top coal caving faces by improving the top coal recovery method.

[0004] The poor stability of the surrounding rock of the working face support due to the increased dip angle of the coal seam is the fundamental reason for the low efficiency of the longwall longwall top coal caving working face. Other methods, such as inclined longwall mining, cannot be implemented due to the difficulty in constructing the peripheral production system.

[0005] For extra-thick coal seams with a dip angle of approximately 45° and a thickness of less than 20m, both strike-side longwall mining with top coal caving and horizontal segmented top coal caving mining suffer from low efficiency and poor top coal recovery. Achieving safe, efficient, and high-recovery mining under these conditions has become an important direction for the development of coal mining technology. This invention provides a new approach to solving the above problems through a novel design of a coal mining method under these conditions. Summary of the Invention

[0006] Technical Problem: The key to successful inclined longwall longwall mining is establishing a stable production system and ensuring the stability of the hydraulic support production process. The purpose of this invention is to provide an inclined longwall longwall mining method suitable for steeply inclined, extra-thick coal seams by modifying the layout of the mining roadways and the coal release supports and processes.

[0007] Technical solution: This invention discloses a fully mechanized longwall mining method for steeply inclined extra-thick coal seams, the steps of which are as follows: S1. In steeply inclined extra-thick coal seams, the working face is arranged according to the inclined longwall mining method. An intake airway and a return airway are constructed on both sides of the working face, respectively. The intake airway is constructed along the top of the coal seam, and the return airway is constructed along the bottom of the coal seam. S2. Construct an opening along the coal seam floor. Construct a coal conveying ramp between the end of the return air transport inclined roadway and one end of the opening. Excavate the air intake track inclined roadway towards the coal seam floor and connect it with the other end of the opening to form a connecting roadway. S3. Hydraulic supports and coal mining machines are used to mine along the working face. The slope and the connecting roadway are pulled down simultaneously with the working face mining. The thickness of the pull-down is equal to the mining cycle advance of the working face. The goaf of the working face collapses naturally. Only the abandoned section of the intake roadway, the slope and the goaf above the connecting roadway are filled and supported during mining, so that the slope and the connecting roadway remain unchanged with the mining height. S4, the hydraulic support moves under pressure, and S3 is executed in a cycle to complete the mining of the entire working face.

[0008] Furthermore, the specific steps for arranging working faces in steeply inclined extra-thick coal seams using inclined longwall mining are as follows: Inclined longwall working faces are arranged in the uphill stages of the main roadway and transport roadway, and the longwall mining process of top coal caving is adopted to achieve the recovery of the working faces; the working faces are advanced obliquely along the bottom of the coal seam, and the intake roadway of the working faces is excavated along the top of the coal seam, with the cross-section of the intake roadway designed according to production needs; the bottom of the return air transport roadway of the working faces arranged along the bottom of the coal seam retains a bottom coal layer with a thickness of 1.0m to 1.5m to construct a slope connecting the working faces, and an enamel chute is placed in the slope.

[0009] Furthermore, after the inclined wind tunnel, which is excavated from the main roadway along the coal seam roof, reaches the horizontal height of the working face cut-out, it continues to excavate upwards. Distance, h is the coal seam thickness, α is the coal seam dip angle; after the intake track inclined roadway is excavated to the position, the connecting roadway is excavated downward at 10° towards the coal seam floor to the working face opening position, and the working face opening is excavated along the horizontal direction of the coal seam floor rock and connected with the return air transport inclined roadway.

[0010] Furthermore, the intake roadway of the working face is supported according to the stability requirements of the surrounding rock. In addition to supporting the roof and sides, the return air transport roadway of the working face needs to be anchored with roof anchor bolts and floor anchor bolts respectively. The roof anchor bolts and floor anchor bolts are driven vertically into the roof and floor of the roadway, respectively, and the floor anchor bolts are driven vertically into the floor of the roadway. The length of the floor anchor bolts exceeds the bottom coal by 0.2 to 0.3 m. After the return air transport roadway reaches the opening position of the working face, it is horizontally excavated towards the bottom of the coal seam to form the end working space of the bottom rock strata.

[0011] Furthermore, at the end of the return air transport inclined roadway, a slope is constructed at a 20° downward inclination along the retained bottom coal to connect with the bottom plate of the working face. Enameled chutes are arranged on the slope to transfer the coal mined from the working face to the return air transport inclined roadway, and the coal is transported out by gravity.

[0012] Furthermore, a connecting roadway inclined upward at 10° is arranged at the end of the air intake track inclined roadway, and the connecting roadway is used to place the equipment train.

[0013] Furthermore, after each bottoming process of the connecting roadway between the intake airway and the working face, the abandoned sections of the intake airway and the roof of the connecting roadway generated during mining are filled and reinforced with grouting material. The filling and reinforcement are supported by a frame, and the filling thickness is equal to the bottoming thickness. After 4 to 5 filling cycles, the filling body formed by the filling is anchored once with anchor cables. The anchor cable length is required to anchor within the roof rock layer for more than 1.0m, and the anchor cable support strength is greater than the weight of 4 to 5 filling layers.

[0014] Furthermore, the hydraulic support used in the longwall mining is equipped with a telescopic front beam at the front end, and the hydraulic support top beam is equipped with a telescopic support column to abut against the coal face. No coal discharge mechanism is set at the rear, and the shield beam completely isolates the goaf from the working face. After the coal mining machine cuts the coal, the side plates temporarily protect the roof, the push scraper conveyor is pushed to the coal face, then the side plates are retracted, the hydraulic support moves under pressure, the extended support column is fixed to the coal face, and the telescopic front beam is retracted to discharge coal. Depending on the top coal crushing conditions, single or multiple supports are used for coal discharge.

[0015] Beneficial effects: This method is designed for fully mechanized longwall mining of steeply inclined extra-thick coal seams. First, an intake airway and a return airway are constructed on both sides of the working face. The intake airway is constructed close to the coal seam roof, and the return airway is constructed close to the coal seam floor, facilitating mining downwards along the extra-thick coal seam. The hydraulic supports of the working face are arranged horizontally. The coal mining machine and scraper conveyor are supported by the coal wall along the coal seam dip. The hydraulic supports prevent sliding down along the coal seam dip by pushing jacks and side supports. The hydraulic supports, scraper conveyor, and coal mining machine of the working face do not have the problem of tilting and sliding down towards the longwall working face. A coal conveying ramp is constructed between the end of the return air haulage inclined roadway and one end of the opening cut. The intake air haulage inclined roadway is excavated towards the coal seam floor and connects to the other end of the opening cut to form a connecting roadway. The goaf of the working face collapses naturally. Only the abandoned sections of the intake air haulage inclined roadway, the ramp, and the goaf above the connecting roadway are backfilled and supported during mining, ensuring that the ramp and connecting roadway remain constant with the mining height. The goaf of the working face collapses naturally without backfilling. Only the abandoned sections of the intake air haulage inclined roadway and the roof of the connecting roadway are backfilled and reinforced with grouting material, using a frame support and backfilling reinforcement. The working face uses a telescopic front beam for coal release, achieving complete isolation between the working face and the goaf. The changes in the strata of the intake air haulage inclined roadway and the return air haulage inclined roadway provide a safe space for operations at the working face end, and the coal seam dip angle simplifies the coal conveying system of the haulage inclined roadway. Compared to current longwall mining methods for steeply inclined extra-thick coal seams, this invention offers superior stability in hydraulic supports, scraper conveyors, and mining machines, leading to increased production efficiency. Compared to horizontal segmented top coal caving methods, it is more advantageous for top coal recovery, particularly in extra-thick coal seams with a dip angle of approximately 45° and a thickness of less than 20m. This invention is of great significance to the development of steeply inclined extra-thick coal seam mining technology and provides valuable insights for improving methods in mining steeply inclined medium-thick coal seams. Attached Figure Description

[0016] Figure 1 This is a plan view of the working face roadway layout for a fully mechanized longwall mining method for steeply inclined extra-thick coal seams according to the present invention.

[0017] Figure 2 This is a diagram showing the working face return air transport inclined roadway level and working face end layout of the present invention.

[0018] Figure 3 This is a diagram showing the layout of the inclined roadway and the end of the working face in this invention.

[0019] Figure 4 This is a schematic diagram of the working face hydraulic support stability and coal discharge control of the present invention.

[0020] In the diagram: 1-Working face, 2-Intake airway inclined roadway, 3-Return airway inclined roadway, 4-Main track roadway, 5-Main transport roadway, 6-End of working face track roadway, 7-End of working face transport roadway, 8-Coal seam, 9-Coal seam roof, 10-Coal seam floor, 11-Roof anchor bolt, 12-Floor anchor bolt, 13-Bottom coal, 14-Slope, 15-Connecting roadway, 16-Roof filling material of roadway, 17-Anchor cable, 18-Telescopic front beam, 19-Side support pillar. Detailed Implementation

[0021] The following description, in conjunction with the accompanying drawings, further illustrates one embodiment of the present invention: This invention discloses a fully mechanized longwall mining method for steeply inclined extra-thick coal seams. The working face and the mining roadway are arranged in an inclined longwall mining manner. By changing the stratum of the mining roadway and its connection with the working face, the stability of the production equipment and processes at the end of the working face is ensured. Furthermore, by changing the hydraulic support and the coal release method, the stability of the hydraulic support is ensured, thereby achieving the smooth completion of the production process. The steps are as follows.

[0022] In S1, in the steeply inclined extra-thick coal seam 8, an inclined longwall working face 1 is arranged in the uphill stage of the main track roadway 4 and the main transport roadway 5. An intake track roadway 2 and a return air transport roadway 3 are constructed on both sides of the working face 1, including the end of the working face track roadway 6 and the end of the working face transport roadway 7. The intake track roadway 2 is constructed against the top plate 9 of the coal seam, and the return air transport roadway 3 is constructed against the bottom plate 10 of the coal seam. After the main roadway 4 is excavated along the roof of the coal seam 9, the inclined roadway 2 is excavated to the horizontal position where the cutting hole of the working face 1 is located, and then the excavation continues upward. Distance, h is the coal seam thickness, α is the coal seam dip angle; After the intake track inclined roadway 2 reaches the working face opening position, it is horizontally excavated towards the coal seam floor 10 to the coal seam floor rock stratum 10. After the intake track inclined roadway 2 reaches the position, it is inclined downward at 10° towards the coal seam floor 10 to the working face opening position. Since the working face is a steeply inclined extra-thick coal seam 8, the intake airway 2 and return airway 3 cannot fill the entire thickness of the coal seam 8. After the intake airway 2 and return airway 3 are constructed according to the actual size requirements, there is still a thick coal seam below the bottom plate of the intake airway 2 and above the top plate of the return airway 3. The return air transport inclined roadway 3 is excavated from the transport roadway 5 along the bottom of the coal seam. A 1.0-1.5 m thick layer of bottom coal 13 is retained at the bottom of the roadway. The bottom of the roadway is anchored with bottom plate anchor bolts 12, and the length of the bottom plate anchor bolts 12 should be anchored into the rock strata of the bottom of the coal seam 10 by 0.2-0.3 m.

[0023] S2. Construct an opening along the coal seam floor 10. Construct a coal conveying ramp 14 between the end of the return air transport inclined roadway 3 and one end of the opening. Excavate the air intake track inclined roadway 2 towards the coal seam floor 1 and connect it with the other end of the opening to form a connecting roadway 15. After the connecting roadway 15 is excavated to its position, the working face is excavated along the horizontal direction of the coal seam floor slab 10, and connected to the return air transport inclined roadway 2, forming a complete production system. The production system equipment for working face 1 is then installed, including a fully mechanized mining support system with a telescopic front beam 18 and side support columns 19, either a shield-type or a support-shield type. Material and personnel are transported from the working face via the intake air track inclined roadway 1, while coal is transported via the return air transport inclined roadway. The equipment train is located within the connecting roadway 15.

[0024] S3. Using hydraulic supports and a coal mining machine, coal is mined along working face 1. During the mining process, 2-3 advance coal mining machines retract the hydraulic support side plates and support columns. After the coal mining machine cuts the coal, it first extends the side plates to temporarily support the roof, then pushes the scraper conveyor to the coal wall, then moves the support under pressure, and finally extends the support column 19 to fix it on the coal wall. Coal is released by retracting the hydraulic support telescopic front beam 19. Depending on the top coal crushing conditions, single or multiple supports can be used for coal release. After the coal release is completed, the hydraulic support telescopic front beam 19 is extended and the side plates are opened. The coal from working face 1 is transported by scraper conveyor to the enamel chute set on the slope 14 in the return air transport inclined roadway 3, and then transferred from the enamel chute to the gravity flow section of the return air transport inclined roadway 3 and then to the main transport roadway. The slope 14 and the connecting roadway 15 are pulled down simultaneously with the mining of the working face 1. The thickness of the pull-down is equal to the mining cycle advance of the working face 1. The goaf of the working face 1 collapses naturally. Only the goaf above the slope 14 and the connecting roadway 15 is filled and supported. The height of the slope 14 and the connecting roadway 15 remains unchanged during the mining process. The first cut of the working face is to pull the bottom of the inclined ramp 14 in the return air transport inclined roadway 3 and the connecting roadway 15 on the side of the air intake track inclined roadway 2. The bottom thickness is equal to the cycle advance of the working face. After the bottoming of the connecting tunnel 15 is completed, the top plate of the intake track inclined tunnel 2 and the connecting tunnel 15 is filled with filling material to form a filling body (16). Each cycle of filling is repeated 4 to 5 times. Anchor cables 17 are used to anchor the filling false top. The length of the anchor cables 19 should meet the requirement of anchoring more than 1.0m in the top plate rock layer.

[0025] S4, the hydraulic support moves under pressure, and S3 is executed cyclically to complete the mining of the entire working face. The above describes in detail the embodiments of the present invention. Except as indicated in the figures, the terms "cutting eye," "coal seam thickness," "coal seam dip angle," "coal mining machine," "hydraulic support," "scraper conveyor," "side guard plate," and "equipment train" used in the embodiments are commonly used concepts in the art, and the specific implementation process described will be understood by those skilled in the art. The above description is merely a detailed technical solution and working principle of the present invention. Any modifications, equivalent substitutions, and improvements made within the principles and spirit of the present invention should be included within the protection scope of the present invention.

Claims

1. A fully mechanized longwall mining method for steeply inclined extra-thick coal seams, characterized in that, The steps are as follows: S1. In a steeply inclined extra-thick coal seam, the working face (1) is arranged according to the inclined longwall mining method. An intake track inclined roadway (2) and a return air transport inclined roadway (3) are constructed on both sides of the working face (1). The intake track inclined roadway (2) is constructed against the top plate (9) of the coal seam, and the return air transport inclined roadway (3) is constructed against the bottom plate (10) of the coal seam. S2. Construct an opening along the bottom plate of the coal seam (10), and construct a coal conveying ramp (14) between the end of the return air transport inclined roadway (3) and one end of the opening. Excavate the air intake track inclined roadway (2) towards the bottom plate of the coal seam (1) and connect it with the other end of the opening to form a connecting roadway (15). S3. Use hydraulic supports and coal mining machines to mine along the working face (1). The slope (14) and the connecting roadway (15) are pulled down synchronously with the mining of the working face (1). The thickness of the pull-down is equal to the mining cycle advance of the working face (1). The goaf of the working face (1) collapses naturally. Only the abandoned section of the intake roadway (2) generated by mining, the goaf above the slope (14) and the connecting roadway (15) are filled and supported by mining, so that the slope (14) and the connecting roadway (15) remain unchanged with the mining height. S4, the hydraulic support moves under pressure, and S3 is executed in a cycle to complete the mining of the entire working face.

2. The fully mechanized longwall mining method for steeply inclined extra-thick coal seams according to claim 1, characterized in that, The specific steps for setting up the working face (1) in the steeply inclined extra-thick coal seam according to the inclined longwall mining method are as follows: the inclined longwall working face (1) is set up in the uphill stage of the main roadway (4) and the transport roadway (5), and the longwall mining method of top coal caving is adopted to realize the mining of the working face (1); the working face (1) is advanced obliquely along the bottom plate of the coal seam, and the intake roadway (2) of the working face (1) is excavated along the top plate of the coal seam. The cross section of the intake roadway (2) is designed according to the production needs; the return air transport roadway (3) of the working face (1) is set up along the bottom plate of the coal seam, and the bottom plate retains a bottom coal (13) with a thickness of 1.0m to 1.5m in order to construct the slope (14) connecting the working face (1). An enamel chute is placed in the slope (14).

3. The fully mechanized longwall mining method for steeply inclined extra-thick coal seams according to claim 2, characterized in that, After the inclined wind tunnel (2), which is excavated from the main roadway (4) along the roof of the coal seam (9), reaches the horizontal height of the cutting hole at the working face (1), it continues to excavate upwards. Distance, h is the coal seam thickness, α is the coal seam dip angle; after the intake track inclined roadway (2) is excavated to the position, the connecting roadway (15) is excavated downward at 10° towards the coal seam floor (10) to the working face opening position, and the working face opening is excavated along the horizontal direction of the coal seam floor rock (10) and connected with the return air transport inclined roadway (2).

4. The fully mechanized longwall mining method for steeply inclined extra-thick coal seams according to claim 4, characterized in that, The working face intake roadway (2) is supported according to the stability requirements of the surrounding rock. In addition to supporting the roof and sidewalls, the working face return air transport roadway (3) needs to be anchored with roof anchor bolts (11) and bottom anchor bolts (12) respectively. The roof anchor bolts (11) and bottom anchor bolts (12) are driven vertically into the roadway roof and bottom, respectively. The length of the roadway bottom anchor bolts (12) exceeds the bottom coal by 0.2 to 0.3 m. After the return air transport roadway (2) reaches the working face opening position, it is horizontally excavated towards the coal seam bottom plate (10) to form the end working space of the coal seam bottom stratum.

5. The fully mechanized longwall mining method for steeply inclined extra-thick coal seams according to claim 2, characterized in that, At the end of the return air transport inclined roadway (3), a slope is constructed at a 20° downward inclination along the retained bottom coal to connect with the bottom plate of the working face (1). An enamel chute is arranged on the slope to transfer the coal mined from the working face to the return air transport inclined roadway, and the coal is transported out by gravity.

6. The fully mechanized longwall mining method for steeply inclined extra-thick coal seams according to claim 2, characterized in that, An upward-inclined connecting roadway (2) is arranged at the end of the air intake track inclined roadway (2), and the connecting roadway is used to place the equipment train.

7. The fully mechanized longwall mining method for steeply inclined extra-thick coal seams according to claim 1, characterized in that, After each bottoming process, the roof of the abandoned section of the intake track (2) and the connecting roadway (15) generated during mining is filled and reinforced with grouting material. The roof is reinforced with scaffolding support and filling. The filling thickness is equal to the bottoming thickness. After 4 to 5 filling cycles, the filling body (16) formed by the filling is anchored once with anchor cable (17). The length of anchor cable (17) is sufficient to anchor more than 1.0m in the roof rock layer. The support strength of anchor cable (17) is greater than the weight of 4 to 5 filling layers.

8. The fully mechanized longwall mining method for steeply inclined extra-thick coal seams according to claim 7, characterized in that, The hydraulic support used for mining has a telescopic front beam (18) at the front end and a telescopic support column (19) on the top beam of the hydraulic support to abut against the coal wall of the working face. No coal release mechanism is set at the rear. The shield beam completely isolates the goaf from the working face. After the coal mining machine cuts the coal, the side plate temporarily protects the roof, pushes the scraper conveyor to the coal wall, then retracts the side plate, the hydraulic support moves under pressure, the extension support column (19) is fixed on the coal wall, and the telescopic front beam (18) is retracted to release the coal. Depending on the top coal crushing conditions, single or multiple supports are used for coal release.

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