Coal mine drilling residue gas leading-out system

Abstract

The application discloses a coal mine drilling slag gas leading-out system and relates to the field of coal mine equipment. The coal mine drilling slag gas leading-out system comprises a blowout preventer, a slag gas separator, a slag gas pipe, a gas pipe, a pumping and exhausting pump and a slag water pipe. The slag gas separator comprises a separator shell, a rotating shaft, a tee joint, a discharge joint and at least three blades. The separator shell is in a cylindrical shape and horizontally arranged. The rotating shaft is coaxially arranged with the separator shell and is installed on the separator shell. The blades are circumferentially and evenly distributed around the rotating shaft and are connected with the rotating shaft. The blades divide the internal space of the separator shell into multiple material containing cavities. The tee joint is arranged above the separator shell and is connected with the separator shell. The discharge joint is connected with the lower end of the separator shell. One material containing cavity is not simultaneously connected with the tee joint and the discharge joint. The slag gas pipe is connected with the blowout preventer and a joint cross pipe. The gas pipe is connected with the tee joint. The pumping and exhausting pump is arranged on the gas pipe. The slag water pipe is connected with the discharge joint.

Description

Technical Field

[0001] This invention relates to the field of coal mine equipment, and more particularly to a coal mine borehole slag gas extraction system. Background Technology

[0002] Coal seams in mines often contain methane gas, which needs to be drained by drilling before mining. Otherwise, methane overflow during subsequent mining will cause serious safety accidents.

[0003] The equipment used for borehole drainage includes a drilling rig, a blowout preventer (BOP), a drain line, and a slag-gas separator. The borehole drainage process involves first drilling a relatively large, shallow hole in the mine wall to install the BOP; then, the BOP is inserted into the hole, and water or gas is injected into it to inflate the expansion bladder, sealing the borehole; next, a smaller drill rod and drill bit are passed through the BOP, sealing the connection between the drill rod and the BOP; then, drilling continues to the depth of the coal seam. During and after drilling, the drill cuttings, water, and gas are discharged through the gap between the BOP and the drill rod, and guided through the drain line to the slag-gas separator. The separator separates the gas, allowing it to be collected separately, while the drill cuttings and water are discharged separately. Patent application number 201920567193.7 discloses the above-mentioned prior art.

[0004] Currently used slag-gas separation devices sometimes have complex structures and sometimes insufficient separation efficiency, which may lead to some gas entering the drill cuttings and water discharge outlets. Taking the slag-gas separation device of patent application number 201920567193.7 as an example, this slag-gas separation device has a simple structure, using a gas extraction pipe and a slag discharge drainage hose connected to a blowout preventer. However, the gas extraction pipe and the slag discharge drainage hose are also in a connected state. If the gas discharge volume is large, a large amount of gas may be discharged from the slag discharge drainage hose.

[0005] In addition, the above-mentioned drilling and drainage process involves drilling the blowout preventer hole first, then installing the blowout preventer hole, then passing the drill rod and drill bit through the blowout preventer and sealing it, and then drilling and draining the hole. This process is quite cumbersome and should be simplified recently. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a coal mine borehole slag gas extraction system with better separation effect between gas and slag water in the slag gas separation device.

[0007] The technical solution adopted to solve the above problems is as follows: The coal mine drilling slag and gas extraction system includes a blowout preventer, a slag and gas separator, a slag and gas pipe, a gas pipe, a drainage pump, and a slag and water pipe; the slag and gas separator includes a separator shell, a rotating shaft, blades, a tee joint, and a discharge joint; the separator shell is cylindrical and horizontally arranged, the rotating shaft is coaxial with the separator shell and installed on the separator shell, the number of blades is at least N, N≥3, each blade is evenly distributed around the rotating shaft and connected to the rotating shaft, each blade divides the internal space of the separator shell into N material chambers; the tee joint includes a joint vertical pipe and a joint horizontal pipe, the tee joint is located above the separator shell, the lower end of the joint vertical pipe is connected to the separator shell; the discharge joint is connected to the lower end of the separator shell; one material chamber is not simultaneously connected to the tee joint and the discharge joint; the slag and gas pipe is connected to the blowout preventer and the joint horizontal pipe; the gas pipe is connected to the upper end of the joint vertical pipe, and the drainage pump is installed on the gas pipe; the slag and water pipe is connected to the discharge joint.

[0008] Furthermore, the tee connector is offset from the center of the separator housing, allowing the material entering the material chamber to drive the blades to rotate; the axis of the discharge connector passes through the center of the separator housing.

[0009] Furthermore, N = 4.

[0010] Furthermore, a filter screen is installed inside the vertical pipe of the connector, and the filter screen is located above the horizontal pipe of the connector.

[0011] Furthermore, the coal mine borehole slag and gas extraction system includes a drilling rig, which comprises a drill rod, a drill bit, a drill rod frame, a drill rod driver, and a drill rod seat. The drill rod seat is connected to the drill rod frame, the drill rod driver is mounted on the drill rod frame and located behind the drill rod seat, the drill rod passes through the drill rod seat and is connected to the drill rod driver, and the drill rod driver can drive the drill rod to rotate and move back and forth. The drill bit is connected to the front end of the drill rod, and the rear end of the drill bit has a drill bit transmission component.

[0012] The blowout preventer (BOP) includes a BOP housing, an expansion bladder, a drain pipe, a secondary drill bit, telescopic cylinders, and an air pump. The BOP housing is located in front of the drill pipe seat and is cylindrical in shape. It fits over the drill pipe, and its rear end is sealed to the drill pipe via a sealing structure. A drain cavity is formed between the BOP housing and the expansion bladder. Two telescopic cylinders are spaced apart laterally and are aligned with the drill pipe. They are mounted on the drill pipe frame and connected to the BOP housing. The expansion bladder is fitted onto the BOP housing, and the air pump is mounted on the drilling rig and connected to the expansion bladder. The drain pipe is located behind the expansion bladder and connected to the BOP housing, communicating with the drain cavity. The secondary drill bit is mounted at the front end of the BOP housing and is rotatable. It has a secondary drill bit hole, and a secondary drill bit drive mechanism is installed on the inner wall of the hole.

[0013] The drill bit moves backward to enter and mate with the auxiliary drill bit hole. At this time, the drill bit can drive the auxiliary drill bit to rotate through the drill bit drive component and the auxiliary drill bit drive component. The drill bit and the auxiliary drill bit form a drill bit kit.

[0014] Furthermore, the front end of the blowout preventer housing has a mounting protrusion, the auxiliary drill bit is mounted on the mounting protrusion, and an elastic retaining ring is provided between the auxiliary drill bit and the mounting protrusion to restrict the axial movement of the auxiliary drill bit.

[0015] Furthermore, the drill bit drive component is a rear protrusion, and the auxiliary drill bit drive component is an inner protrusion; when the drill bit drives the auxiliary drill bit to rotate, the side of the rear protrusion abuts against the side of the inner protrusion.

[0016] Furthermore, there are two rear protrusions and two inner protrusions. The two rear protrusions are symmetrically arranged with the drill bit axis as the center, and the two inner protrusions are symmetrically arranged with the auxiliary drill bit axis as the center.

[0017] Furthermore, the sealing structure is a packing seal structure.

[0018] The beneficial effects of this invention are as follows: 1. The working process of the slag-gas separator is as follows: During and after drilling, the drill cuttings, water, and gas discharged are guided into the three-way connector through the slag-gas pipe. The gas is discharged from the gas pipe under the action of the extraction pump. The slag and water fall into the material chamber inside the separator shell due to their own gravity. The rotation of the shaft drives the slag and water collected in each material chamber to move towards the discharge connector for discharge, while the empty material chamber collects slag and water towards the vertical pipe of the connector. In this way, the shaft rotates continuously, and the slag-gas separator continuously collects and discharges slag and water. During the discharge of slag and water, due to the isolation of the blades, the three-way connector and the discharge connector are not connected, which can prevent gas from being discharged from the discharge connector. Even if the amount of gas is large, and some gas that is not immediately extracted by the extraction pump enters the material chamber and mixes with the slag and water and is discharged from the discharge connector, it is only a very small amount and will not cause danger. Therefore, the slag-gas separator of this invention has the advantages of simple structure and good effect in separating gas and preventing gas from being discharged with slag and water.

[0019] 2. The present invention is further improved and optimized with the blowout preventer device, which has the beneficial effects of simplifying the drilling and pumping operation and reducing the labor intensity of the operation, as detailed in the specific implementation method below. Attached Figure Description

[0020] Figure 1 This is a structural diagram of a coal mine borehole slag and gas extraction system;

[0021] Figure 2 This is a structural diagram of a slag-gas separator;

[0022] Figure 3 This is a structural diagram of the drilling rig and blowout preventer;

[0023] Figure 4This is a structural diagram of the blowout preventer;

[0024] Figure 5 This is a diagram of the front-end structure of the blowout preventer;

[0025] Figure 6 This is a diagram showing how the drill bit drives the auxiliary drill bit.

[0026] Figure 7 This is a schematic diagram of drilling step one;

[0027] Figure 8 This is a schematic diagram of drilling step two;

[0028] The following components are marked in the diagram: Blowout preventer 1, Blowout preventer housing 11, Mounting protrusion 111, Expansion bladder 12, Outlet pipe 13, Sealing structure 14, Auxiliary drill bit 15, Auxiliary drill bit hole 151, Auxiliary drill bit transmission component 152, Telescopic cylinder 16, Outlet chamber 17, Slag-gas separator 2, Separator housing 21, Material chamber 211, Rotating shaft 22, Blade 23, T-joint 24, Joint vertical pipe 241, Joint horizontal pipe 242, Filter screen 243, Discharge joint 25, Slag-gas pipe 3, Gas pipe 4, Pump 5, Slag-water pipe 6, Drilling rig 7, Drill rod 72, Drill bit 73, Drill bit transmission component 731, Drill rod frame 71, Drill rod driver 74, Drill rod seat 75. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0030] like Figure 1 and Figure 2 As shown, the coal mine borehole slag and gas extraction system includes a blowout preventer 1, a slag and gas separator 2, a slag and gas pipe 3, a gas pipe 4, a drainage pump 5, and a slag and water pipe 6. The slag and gas separator 2 includes a separator housing 21, a rotating shaft 22, blades 23, a tee connector 24, and a discharge connector 25. The separator housing 21 is cylindrical and horizontally positioned. The rotating shaft 22 is coaxially mounted on the separator housing 21. The number of blades 23 is at least N, where N≥3. Each blade 23 is evenly distributed around the rotating shaft 22 and connected to it. Each blade 23 removes the slag and gas from the separator housing 21. The internal space is divided into N material receiving chambers 211; the tee connector 24 includes a connector vertical pipe 241 and a connector horizontal pipe 242, the tee connector 24 is located above the separator housing 21, and the lower end of the connector vertical pipe 241 is connected to the separator housing 21; the discharge connector 25 is connected to the lower end of the separator housing 21; one material receiving chamber 211 is not simultaneously connected to the tee connector 24 and the discharge connector 25; the slag gas pipe 3 is connected to the anti-blowout device 1 and the connector horizontal pipe 242; the gas pipe 4 is connected to the upper end of the connector vertical pipe 241, and the extraction pump 5 is installed on the gas pipe 4; the slag water pipe 6 is connected to the discharge connector 25. Preferably, N=4.

[0031] The above technical solution mainly improves the slag-gas separator 2, while the rest of the structure can be the same as the existing technology.

[0032] The working process of the slag-gas separator is as follows: During and after drilling, the drill cuttings, water, and gas discharged are guided into the three-way connector 24 through the slag-gas pipe 3. The gas is discharged from the gas pipe 4 under the action of the extraction pump 5. The slag and water, due to their own gravity, fall into the material chamber 211 inside the separator housing 21. The rotating shaft 22 drives the slag and water collected in each material chamber 211 to move towards the discharge connector 25 for discharge, while simultaneously causing the empty material chamber 211 to collect slag and water towards the connector vertical pipe 241. As the rotating shaft 22 rotates continuously, the slag-gas separator continuously collects and discharges slag and water. During the discharge of slag and water, due to the isolation of the blades 23, the three-way connector 24 and the discharge connector 25 are not connected, preventing gas from being discharged from the discharge connector 25. Even if the gas volume is large, and some gas that is not immediately extracted by the extraction pump 5 enters the material chamber 211 and mixes with the slag and water before being discharged from the discharge connector 25, it is only a very small amount and will not cause danger. Therefore, the slag-gas separator 2 of the present invention has the advantages of simple structure and good effect in separating gas and preventing gas from being discharged with slag and water.

[0033] The rotating shaft 22 can be driven to rotate by a motor or other drive device. To further simplify the structure, the present invention preferably sets the three-way connector 24 off-center from the center of the separator housing 21, so that the material in the input chamber 211 can drive the blades 23 to rotate; the axis of the discharge connector 25 passes through the center of the separator housing 21.

[0034] like Figure 2 As shown, the slag and water enter the right-hand material chamber 211 instead of the left-hand material chamber 211. The right-hand blade 23 bears the weight of the slag and water, so the blade 23 rotates automatically, and there is no need to set a drive device to drive the rotating shaft 22.

[0035] The pump 5 should have sufficient suction force, but some small solid materials may be sucked into the pump 5. In order to avoid this, it is preferable to install a filter screen 243 inside the connector vertical pipe 241, with the filter screen 243 located above the connector horizontal pipe 242.

[0036] To simplify the drilling and extraction operation process and reduce labor intensity, the present invention preferably includes further improvements such as... Figures 3 to 6As shown, the coal mine borehole slag and gas extraction system includes a drilling rig 7, which includes a drill rod 72, a drill bit 73, a drill rod frame 71, a drill rod driver 74, and a drill rod seat 75. The drill rod seat 75 is connected to the drill rod frame 71, and the drill rod driver 74 is mounted on the drill rod frame 71 and located behind the drill rod seat 75. The drill rod 72 passes through the drill rod seat 75 and is connected to the drill rod driver 74, which can drive the drill rod to rotate and move back and forth. The drill bit 73 is connected to the front end of the drill rod 72. The drill bit 73 has a drill bit drive component 731 at its rear end; the blowout preventer 1 includes a blowout preventer housing 11, an expansion bladder 12, a guide tube 13, an auxiliary drill bit 15, a telescopic cylinder 16, and an air pump; the blowout preventer housing 11 is located in front of the drill rod seat 75, and the blowout preventer housing 11 is cylindrical in shape. The blowout preventer housing 11 is fitted over the drill rod 72, and the rear end of the blowout preventer housing 11 is sealed to the drill rod 72 through a sealing structure 14. The blowout preventer housing 11 and the expansion bladder 12 are connected. A discharge cavity 17 is formed between 2; there are two telescopic cylinders 16, which are spaced apart in the left and right direction. The telescopic cylinders 16 are arranged in the same direction as the drill rod 72. The telescopic cylinders 16 are installed on the drill rod frame 71 and connected to the blowout preventer housing 11; the expansion bladder 12 is fitted on the blowout preventer housing 11, and the air pump is installed on the drilling rig 7 and connected to the expansion bladder 12; the discharge pipe 13 is located behind the expansion bladder 12 and connected to the blowout preventer housing 11. The discharge pipe 13 is connected to the discharge cavity 17; the auxiliary drill bit 15 is installed at the front end of the blowout preventer housing 11 and can rotate. The auxiliary drill bit 15 has an auxiliary drill bit hole 151. An auxiliary drill bit transmission component 152 is provided on the inner wall of the auxiliary drill bit hole 151; the drill bit 73 can move backward to enter the auxiliary drill bit hole 151 and cooperate with the auxiliary drill bit hole 151. At this time, the drill bit 73 can drive the auxiliary drill bit 15 to rotate through the drill bit transmission component 731 and the auxiliary drill bit transmission component 152. The drill bit 73 and the auxiliary drill bit 15 form a drill bit kit.

[0037] The drilling rig 7 is a prior art product. The present invention's description of the drilling rig 7 including a drill rod 72, a drill bit 73, a drill rod frame 71, a drill rod driver 74, and a drill rod seat 75; the drill rod seat 75 is connected to the drill rod frame 71, the drill rod driver 74 is mounted on the drill rod frame 71 and located behind the drill rod seat 75, the drill rod 72 passes through the drill rod seat 75 and is connected to the drill rod driver 74, and the drill rod driver 74 is capable of driving the drill rod to rotate and move back and forth is all prior art. The difference is that the present invention integrates the blowout preventer 1 with the drilling rig and improves the blowout preventer 1.

[0038] The process of drilling and installing the blowout preventer 1 in this invention is as follows: 1. As Figure 7As shown, the drill rod driver 74 drives the drill rod 72 to move backward, and the drill bit 73 moves backward into the auxiliary drill bit hole 151 and engages with it. At this time, the drill bit 73 and the auxiliary drill bit 15 form a drill bit assembly. Then, the drill rod driver 74 drives the drill rod 72 to rotate and simultaneously drives it to move forward. The drill bit 73 drives the auxiliary drill bit 15 to rotate synchronously through the drill bit transmission component 731 and the auxiliary drill bit transmission component 152. At the same time, the telescopic cylinder 16 drives the blowout preventer housing 11 to move forward, driving the auxiliary drill bit 15 to move forward. The auxiliary drill bit 15 moves forward synchronously with the drill bit 73. The drill bit assembly consisting of the drill bit 73 and the auxiliary drill bit 15 drills a large hole in the mine shaft. At the same time as drilling, the blowout preventer 1 also enters the hole synchronously. II. As Figure 8 As shown, the telescopic cylinder 16 drives the blowout preventer housing 11 to move slightly backward, causing the auxiliary drill bit 15 to move away from the drill bit 73; then water or gas is injected into the expansion bladder 12, causing the expansion bladder 12 to expand and press against the borehole wall, sealing the gap between the expansion bladder 12 and the borehole wall to prevent gas from escaping from there; then the drill rod driver 74 drives the drill rod 72 to drill and move forward, and the drill bit 73 drills out the gas emission hole; during and after drilling, the drill cuttings, water and gas in the coal seam are all poured out from the outlet chamber 17 and enter the outlet pipe 13 for further discharge.

[0039] Compared with existing technologies, the above process eliminates the need for additional equipment to install the blowout preventer 1. The blowout preventer 1 is installed simultaneously during drilling the large hole, eliminating not only the current installation operation of the blowout preventer 1 but also the operation of passing the drill rod 72 and drill bit 73 through the blowout preventer 1 and setting a seal. The large hole is drilled using a drill bit kit consisting of drill bit 73 and auxiliary drill bit 15. Drilling the large hole for the blowout preventer 1 can be done without replacing drill bit 73. Drill bit 73 can also independently drill the small hole for gas extraction, thus simplifying the drilling process. Therefore, this invention significantly simplifies the drilling and extraction operation process and reduces labor intensity. Before drilling and extraction, drill bit 73 and auxiliary drill bit 15 should be thoroughly cleaned to ensure smooth operation for the next use.

[0040] The auxiliary drill bit 15 can be installed as follows: the front end of the blowout preventer housing 11 has a mounting protrusion 111, the auxiliary drill bit 15 is fitted onto the mounting protrusion 111, and an elastic retaining ring 18 is provided between the auxiliary drill bit 15 and the mounting protrusion 111 to restrict the axial movement of the auxiliary drill bit 15. The elastic retaining ring 18 is existing technology and is commonly used for parts fitted onto axial positioning shafts.

[0041] The specific structures of drill bit drive component 731 and auxiliary drill bit drive component 152 are as follows: Figure 6As shown, the drill bit drive component 731 is a rear protrusion, and the auxiliary drill bit drive component 152 is an inner protrusion; when the drill bit 73 drives the auxiliary drill bit 15 to rotate, the side of the rear protrusion abuts against the side of the inner protrusion. Preferably, there are two rear protrusions and two inner protrusions, with the two rear protrusions symmetrically arranged about the axis of the drill bit 73 and the two inner protrusions symmetrically arranged about the axis of the auxiliary drill bit 15.

[0042] The purpose of sealing the blowout preventer housing 11 and the drill pipe 72 with the sealing structure 14 is to prevent gas from leaking out between them. The sealing structure 14 can be any existing sealing structure, such as a packing seal structure.

[0043] The water pump or air pump that fills the expansion bladder 12 with water or air can be installed on the drilling rig 7. The telescopic cylinder 16 is supplied with oil by the hydraulic system of the drilling rig 7.

Claims

1. A coal mine borehole slag and gas extraction system, comprising a blowout preventer (1), a slag and gas separator (2), a slag and gas pipe (3), a gas pipe (4), a drainage pump (5), and a slag and water pipe (6); characterized in that: The equipment includes a drilling rig (7); a slag-gas separator (2) including a separator housing (21), a rotating shaft (22), blades (23), a three-way connector (24), and a discharge connector (25); the separator housing (21) is cylindrical and horizontally arranged, the rotating shaft (22) is coaxially arranged with the separator housing (21) and installed on the separator housing (21), the number of blades (23) is at least N, N≥3, each blade (23) is evenly distributed around the rotating shaft (22) and connected to the rotating shaft (22), each blade (23) divides the internal space of the separator housing (21) into N material chambers (211); the three-way connector (24) Includes a connector vertical pipe (241) and a connector horizontal pipe (242), a tee connector (24) located above the separator housing (21), and the lower end of the connector vertical pipe (241) connected to the separator housing (21); a discharge connector (25) connected to the lower end of the separator housing (21); a material storage chamber (211) not simultaneously connected to the tee connector (24) and the discharge connector (25); a slag gas pipe (3) connected to the anti-blowout device (1) and the connector horizontal pipe (242); a gas pipe (4) connected to the upper end of the connector vertical pipe (241), and a pump (5) installed on the gas pipe (4); and a slag water pipe (6) connected to the discharge connector (25). The drilling rig (7) includes a drill rod (72), a drill bit (73), a drill rod frame (71), a drill rod driver (74), and a drill rod seat (75); the drill rod seat (75) is connected to the drill rod frame (71), the drill rod driver (74) is mounted on the drill rod frame (71) and located behind the drill rod seat (75), the drill rod (72) passes through the drill rod seat (75) and is connected to the drill rod driver (74), and the drill rod driver (74) can drive the drill rod to rotate and move back and forth; the drill bit (73) is connected to the front end of the drill rod (72), and the rear end of the drill bit (73) has a drill bit transmission component (731). The blowout preventer (1) includes a blowout preventer housing (11), an expansion bladder (12), a drain pipe (13), a secondary drill bit (15), and telescopic cylinders (16). The blowout preventer housing (11) is located in front of the drill rod seat (75). The blowout preventer housing (11) is cylindrical in shape and is fitted over the drill rod (72). The rear end of the blowout preventer housing (11) is sealed to the drill rod (72) through a sealing structure (14). A drain cavity (17) is formed between the blowout preventer housing (11) and the expansion bladder (12). There are two telescopic cylinders (16), which are spaced apart in the left and right directions. The telescopic cylinder (16) is set in the same direction as the drill rod (72). The telescopic cylinder (16) is installed on the drill rod frame (71) and connected to the blowout preventer housing (11). The expansion bladder (12) is fitted on the blowout preventer housing (11). The outlet pipe (13) is located behind the expansion bladder (12) and connected to the blowout preventer housing (11). The outlet pipe (13) is connected to the outlet cavity (17). The auxiliary drill bit (15) is installed at the front end of the blowout preventer housing (11) and can rotate. The auxiliary drill bit (15) has an auxiliary drill bit hole (151). An auxiliary drill bit transmission component (152) is provided on the inner wall of the auxiliary drill bit hole (151). The drill bit (73) moves backward to enter the auxiliary drill bit hole (151) and cooperate with the auxiliary drill bit hole (151). At this time, the drill bit (73) can drive the auxiliary drill bit (15) to rotate through the drill bit drive component (731) and the auxiliary drill bit drive component (152). The drill bit (73) and the auxiliary drill bit (15) form a drill bit kit.

2. The coal mine borehole slag and gas extraction system according to claim 1, characterized in that: The three-way connector (24) is offset from the center of the separator housing (21), so that the material entering the material chamber (211) can drive the blade (23) to rotate; the axis of the discharge connector (25) passes through the center of the separator housing (21).

3. The coal mine borehole slag and gas extraction system according to claim 2, characterized in that: N=4。 4. The coal mine borehole slag and gas extraction system according to claim 3, characterized in that: A filter screen (243) is installed inside the connector vertical tube (241), and the filter screen (243) is located above the connector horizontal tube (242).

5. The coal mine borehole slag and gas extraction system according to claim 1, characterized in that: The front end of the blowout preventer housing (11) has a mounting protrusion (111), and the auxiliary drill bit (15) is fitted on the mounting protrusion (111). An elastic retaining ring (18) is provided between the auxiliary drill bit (15) and the mounting protrusion (111), and the elastic retaining ring (18) restricts the axial movement of the auxiliary drill bit (15).

6. The coal mine borehole slag and gas extraction system according to claim 5, characterized in that: The drill bit drive component (731) is a rear protrusion, and the auxiliary drill bit drive component (152) is an inner protrusion; when the drill bit (73) drives the auxiliary drill bit (15) to rotate, the side of the rear protrusion abuts against the side of the inner protrusion.

7. The coal mine borehole slag and gas extraction system according to claim 6, characterized in that: There are two rear protrusions and two inner protrusions. The two rear protrusions are symmetrically arranged with the drill bit (73) axis as the center, and the two inner protrusions are symmetrically arranged with the auxiliary drill bit (15) axis as the center.

8. The coal mine borehole slag and gas extraction system according to claim 7, characterized in that: The sealing structure (14) is a packing seal structure.

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