Green mining method for unmanned coal face using high-pressure water jet cyclone cutting and crushing in steeply inclined coal seams

Abstract

This invention discloses a green mining method for unmanned coal face using high-pressure water jet rotary cutting and crushing in steeply inclined coal seams. The method includes the following steps: planning the working face and mining units based on engineering geological data; opening coal cutting holes and gas drainage holes in the planned mining units; and opening a coal chute at the lower end of the mining unit; mining the mining unit while simultaneously monitoring the mining process and the conditions of the goaf; separating coal and water in the mined coal-water flow; and backfilling the goaf formed after mining. This invention, based on multiple technologies such as unmanned mining faces, high-pressure water jet rotary cutting and crushing, gravity coal extraction using coal-water mixing, coal-water separation using vibrating screens, explosion-proof drone monitoring of the mining area, backfilling-type water-retaining mining, and simultaneous mining of multiple units, proposes a novel green coal mining method that effectively solves the problem of safe and efficient mining of various steeply inclined coal seams.

Description

Technical Field

[0001] This invention relates to the field of coal mining technology, and in particular to a green mining method for unmanned mining faces using high-pressure water jet rotary cutting and crushing of coal seams at steep inclination angles. Background Technology

[0002] Currently, there are corresponding mining methods for most inclined coal seams, but for some steeply inclined coal seams with special occurrence conditions, there are still certain limitations to their successful mining.

[0003] This limitation is mainly reflected in several aspects: (1) The coal seam is relatively thin and has no economic value for mining (except for protective layer mining), so most coal mining enterprises abandon it, resulting in resource waste; (2) In the case of "three soft" coal seams with large dip angles, roof collapse and side fall are very serious during mining, making it difficult to meet both safety and efficiency, resulting in poor profitability for coal mining enterprises; (3) In the case of steeply dipped medium-thick and thin coal seams, the mining technology is relatively backward and it is difficult to achieve mechanization. It is precisely because of the existence of the above limitations that it is very urgent to change the coal mining method, innovate the coal mining technology, and explore a new coal mining method that can adapt to various situations and meet the spirit of green mining, unmanned mining face, safety and efficiency. Summary of the Invention

[0004] The technical problem to be solved by this invention is to overcome the technical difficulty of safe and efficient mining of steeply inclined coal seams, and to provide a green mining method for unmanned mining faces of steeply inclined coal seams using high-pressure water jet rotary cutting and crushing.

[0005] The present invention solves the above-mentioned technical problems through the following technical solution, and the present invention includes the following steps:

[0006] S1, based on engineering geological data, plans the working face and coal mining unit for coal mining operations;

[0007] S11, plan the working face, determine the location of the upper roadway, lower roadway and roadway connecting roadway, open the upper roadway and lower roadway along the working face, one end of the upper roadway and lower roadway respectively connects to the mining area transport roadway, the other end of the upper roadway and lower roadway respectively connects to the roadway connecting roadway, open a return air shaft between the roadway connecting roadway and the surface, or open a dedicated return air roadway to connect to the mining area return air roadway, open a hidden shaft or hidden inclined shaft connecting the dedicated return air roadway and the roadway connecting roadway;

[0008] S12 divides a working face into multiple strip-shaped coal mining units. The number of large groups to be mined is determined based on the coal seam conditions and the number of coal mining units. According to the principle of skip mining, the coal mining units in each large group are not adjacent to each other. The coal mining units in the same large group are numbered with a unified number. Each large group of coal mining units is divided into multiple small groups, and the coal mining units in each small group carry out mining operations simultaneously. The optimal number of groups is 2 large groups, which can save backfilling costs to the greatest extent because the goaf formed after the coal in the last large group of coal mining units is mined does not need to be backfilled.

[0009] S2, In the planned coal mining unit, coal cutting holes and gas drainage holes are opened for coal mining, and a coal chute is opened at the lower end of the coal mining unit;

[0010] S3 is used for mining in coal mining units, while simultaneously monitoring the mining process and the conditions of the roof, walls, and floor of the goaf.

[0011] S4, which separates coal and water in the mined coal-water stream and recycles the separated water;

[0012] S5 is used to backfill the goaf formed after coal mining.

[0013] In step S11, both the upper and lower roadways are air intake roadways. The airflow passes through the roadway connecting roadway and finally gathers at the return air shaft, and is discharged to the ground through the return air shaft.

[0014] If a return air shaft is not set up, a dedicated return airway must be set up. A hidden shaft or a hidden inclined shaft is set up between the dedicated return airway and the connecting roadway of the upper and lower roadways. The airflow from the upper and lower roadways gathers at the hidden shaft or the hidden inclined shaft and flows to the dedicated return airway through the hidden shaft or the hidden inclined shaft, and then enters the main return airway of the mining area through the dedicated return airway.

[0015] In step S11, the lower feed groove of the previous working face is used as the upper feed groove of the next adjacent working face. Only the first working face needs to be set with two feed grooves, and subsequent working faces only need to be set with one feed groove. The lower feed groove of the previous working face can be used as the upper feed groove of the next working face.

[0016] Return air shafts or dedicated return airways and underground shafts or underground inclined shafts are not only used as return air passages for this working face, but also continue to be used as dedicated return air passages for the next working face. As long as the connecting roadways of the upper and lower working faces are connected to each other, the airflow will naturally flow to the return air shaft and discharge to the surface, or flow to the underground shaft or underground inclined shaft and enter the main return airway of the mining area through the dedicated return airway.

[0017] In step S11, the large-diameter return air shaft between the roadway connecting roadway and the ground can also be replaced by several small-diameter vertical air ducts that go directly to the ground.

[0018] The process of setting up the coal cutting hole and gas drainage hole in step S2 is as follows:

[0019] Step S21: Determine the opening position and diameter of the coal cutting hole on the cross-section of the coal mining unit based on the coal seam thickness and the width of the coal mining unit. The cut-off position of the coal cutting hole is located at the coal chute at the lower end of the coal mining unit, that is, the coal cutting hole is connected to the coal chute. The coal cutting hole is parallel to the axis of the coal mining unit. Based on the determined opening position, opening cut-off position and parallel relationship between the coal cutting hole and the axis of the coal mining unit, drill the coal cutting hole in the coal mining unit using a drilling device, and at the same time determine the specifications of the casing placed inside the coal cutting hole.

[0020] Step S22: After the coal cutting hole is formed, the sleeves are connected and lowered one by one from the top of the coal cutting hole until they are lowered to the bottom of the coal cutting hole, i.e., the coal chute.

[0021] Step S23: After the sleeve is in place, secure the sleeve at the upper end.

[0022] Step S24: Determine the opening position and diameter of the gas drainage hole on the cross-section of the coal mining unit based on the coal seam thickness and the width of the coal mining unit. The cut-off position of the gas drainage hole is located at the coal chute at the lower end of the coal mining unit, that is, the gas drainage hole connects to the coal chute. The gas drainage hole is parallel to the axis of the coal mining unit. Based on the determined opening position and cut-off position of the gas drainage hole on the coal mining unit, as well as the parallel relationship between the gas drainage hole and the axis of the coal mining unit, drill the gas drainage hole in the coal mining unit, and at the same time determine the specifications of the steel screen pipe placed in the gas drainage hole.

[0023] Step S25: After the gas drainage hole is formed, steel screen pipes are connected and lowered one by one from the top of the gas drainage hole until they are lowered to the bottom of the gas drainage hole, i.e., the coal chute.

[0024] Step S26: After the steel screen tube is in place, fix the steel screen tube at the upper end.

[0025] The process of setting up the coal chute in step S2 is as follows:

[0026] Step S27: A coal chute is excavated between the bottom of the coal mining unit and the lower roadway to connect with the lower roadway. The bottom plate of the coal chute and the bottom plate of the lower roadway are at the same elevation.

[0027] Step S28: The roof and side walls of the coal chute are supported using the anchor mesh cable spraying support method.

[0028] Step S29: A coal receiving chute is set inside the coal chute. The upper end of the coal receiving chute is located below the lower port of the coal mining unit, and the inclination angle of the coal receiving chute is smaller than the inclination angle of the coal seam floor.

[0029] The coal receiving chute includes a chute bottom plate, a coal retaining plate, and column legs. The coal retaining plate is welded to both sides of the chute bottom plate. The chute bottom plate is inclined at an angle of 15°-30°. The upper end of the chute bottom plate is close to the lower port of the coal mining unit and lower than the lower edge of the lower port of the coal mining unit. The chute bottom plate is trapezoidal, with the shorter base of the trapezoid close to the lower feed roadway and the longer base of the trapezoid close to the coal mining unit. The column legs are fixed to the bottom of the chute bottom plate.

[0030] In step S3, the mining process of the coal mining unit is as follows:

[0031] Step S31: Connect the cutting gun used for coal mining to the high-pressure water conveyance drill rod, and lower the cutting gun along the casing to the end of the casing through the drilling device;

[0032] Step S32: After the cutting gun is lowered into place with the drilling device, a set of high-pressure water rotary joints is added between the drilling device and the high-pressure water conveyance drill rod. The high-pressure water rotary joints are connected to the high-pressure water pump. When the high-pressure water pump is working, the water outlet of the cutting gun sprays out a high-pressure water jet. The drilling device drives the cutting gun to rotate, and the cutting gun starts to rotate and cut and crush coal through the high-pressure water jet.

[0033] In step S33, the cutting gun rotates under the drive of the drilling device and retreats along the casing at set time intervals. As the cutting gun rotates and retreats, it performs high-pressure water jet rotation and retreat coal mining. Under the action of the high-pressure water jet, the casing is quickly cut, and the coal seam around the casing is shredded and falls down, forming a water-coal flow that flows towards the coal chute under the action of the water flow.

[0034] Step S34: Use a small mining drone to monitor the high-pressure water jet rotary cutting and crushing process, the surrounding rock conditions of the goaf, the flow of water and coal, and whether there is siltation on the floor of the goaf.

[0035] The coal-water separation process in step S4 is as follows:

[0036] Step S41: The coal receiving chute is set inside the coal chute opening. A scraper conveyor, a vertical elevator, a dewatering vibrating screen, a belt conveyor, and a deflector are set inside the lower chute. One end of the coal receiving chute is close to the lower port of the coal mining unit, and the other end is connected to the scraper conveyor. One end of the scraper conveyor is located below the coal receiving chute, and the other end is close to the lower side of the vertical elevator. The vertical elevator is close to the belt conveyor, and the upper horizontal part of the vertical elevator is located above the dewatering vibrating screen. The dewatering vibrating screen is located above the belt conveyor, and the deflector is set between the dewatering vibrating screen and the belt conveyor.

[0037] In step S42, the shredded coal cut by the cutting gun is mixed with water to form a coal-water flow. After the coal-water flow flows out of the coal mining unit, it is buffered by the coal receiving chute and falls onto the scraper conveyor. The scraper conveyor directly sends the transferred coal-water flow into the vertical elevator. The vertical elevator transfers the coal-water flow to the dewatering vibrating screen set above the belt conveyor.

[0038] In step S43, the coal and water flow enters the dewatering vibrating screen and is dewatered. The dewatered coal falls directly onto the belt conveyor and is sent away. The dewatered water falls directly onto the water-repellent plate from below the dewatering vibrating screen, is guided by the water-repellent plate to one side of the belt conveyor, and finally flows into the ditch on the other side of the downward channel.

[0039] The process of filling the goaf in step S5 is as follows:

[0040] Step S51: Use steel plates and I-beams to make grid-like side protection plates, and use single pillars for support so that the side protection plates are tightly attached to the outer wall of the coal chute, that is, one side of the lower chute.

[0041] Step S52: Insert a return grout pipe into the side plate at the upper edge of the coal chute to monitor whether the coal chute has been filled and compacted during the grouting process.

[0042] Step S53: Inorganic grouting material is used to fill the coal chute. The filling material is injected from the upper end of the coal mining unit and flows down the inclined bottom plate until it reaches the coal chute.

[0043] Step S54: Goaf filling can only be carried out after the filling material at the coal chute reaches 20MPa. At the end of each continuous filling, the steel screen pipe must be quickly flushed with water to facilitate the extraction of gas from the steel screen pipe.

[0044] Compared with existing technologies, this invention has the following advantages: It is based on unmanned mining faces (safety), high-pressure water jet rotary cutting coal crushing (advanced technology), coal-water mixing to form a water-coal flow for gravity coal extraction (safety and efficiency), vibrating screen coal-water separation (automation), mine explosion-proof drone monitoring of the mining area (artificial intelligence, safety and efficiency), backfilling water-retaining mining (green and environmentally friendly), simultaneous mining of multiple units (high efficiency), minimal mining impact (safety), and the minimum width of the safety coal pillar in the main roadway of the mining area can be reduced to zero (saving non-renewable resources). In the same mining area beyond the first working face, only one roadway needs to be developed for the remaining working faces. This method offers several advantages, including a single connecting roadway (low cost and high efficiency), no need for heavy equipment such as hydraulic supports and coal cutters (reducing costs, significantly reducing face preparation time, and ensuring safety), higher mining efficiency with larger coal seam dip angles (completely changing the current situation where large-angle and steeply inclined coal seams are difficult to mine), zero ground subsidence (ensuring the surface environment and ecology), easy artificial intelligence control of all involved equipment (intelligent mine), and no serious impact from various faults within the working face on normal mining. It proposes a brand-new green coal mining method that effectively solves the problem of safe and efficient mining of various inclined coal seams.

[0045] In this invention, a high-pressure water jet is ejected from the water outlet of the cutting gun. The drilling device drives the cutting gun to rotate, and the cutting gun begins to cut and crush coal through the high-pressure water jet. The cutting gun rotates at a certain speed under the drive of the drilling device, and at the same time, it retreats along the casing at set time intervals. With the rotation and retreat of the cutting gun, the cutting gun performs high-pressure water jet rotation and retreat coal mining. Under the action of the high-pressure water jet, the casing is quickly cut, and the coal seam in a certain range around the casing is crushed and falls down, forming a water-coal flow that flows rapidly towards the coal chute under the action of the water flow, thus realizing safe and low-cost mining of steeply inclined coal seams.

[0046] In this invention, engineering geological data is used to determine the number and width of the planned coal mining units within the working face. The coal mining units are divided into large groups according to the principle of skip mining, and then into smaller groups within the large groups. The groups are sorted and mined in groups. Each time, the coal mining units within a group are mined simultaneously. The optimal number of large groups is 2. When the coal mining units are divided into only 2 large groups, 50% of the goaf does not need to be backfilled, and the backfilling cost can be significantly reduced.

[0047] In this invention, the lower feed roadway of the previous working face serves as the upper feed roadway of the adjacent next working face, which reduces the amount of feed roadway development work and lowers construction costs. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the layout space of the coal mining face (return air shaft);

[0049] Figure 2 This is a schematic diagram of the layout space of the coal mining face (dedicated return airway, underground shaft);

[0050] Figure 3 This is a schematic diagram of the coal mining face layout (return air shaft);

[0051] Figure 4 It is a schematic diagram of the layout of the coal mining face (dedicated return airway, underground shaft);

[0052] Figure 5 This is a schematic diagram of a shared return air shaft;

[0053] Figure 6 This is a schematic diagram showing the shared use of a dedicated return airway and a covered vertical shaft;

[0054] Figure 7 This is a diagram showing the locations of the coal cutting holes and gas drainage holes on the cross-section of the coal mining unit.

[0055] Figure 8 This is a schematic diagram of gas drainage during coal mining;

[0056] Figure 9 This is a schematic diagram of gas drainage during the filling process;

[0057] Figure 10 This is a schematic diagram of a coal cutting, gas extraction, water-coal flow conveying, dewatering, and dewatered coal transportation system.

[0058] Figure 11 This is a structural diagram of a coal receiving chute. Figure 11 In the diagram, a is a top view of the coal receiving chute, and b is a left view of the coal receiving chute.

[0059] Figure 12 This is a schematic diagram of the cutting gun structure. Figure 12 In the diagram, a is a three-dimensional view of the cutting gun, and b is a cross-sectional view of the cutting gun.

[0060] Figure 13 This is a flowchart of the process of the present invention. Detailed Implementation

[0061] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0062] This embodiment uses the 11802 working face of Juxin Coal Mine as an example for detailed explanation. The coal seam involved in this embodiment is No. 18 coal seam, with an average thickness of 2.8m. The roof is siltstone or mudstone, and the floor is mainly mudstone with siltstone as a secondary component. The siltstone has medium mechanical strength, while the mudstone has low mechanical strength and poor stability.

[0063] In this embodiment, the dip angle of coal seam #18 is 32-36°, with an average of 34° (locally reaching 50°). The coal seam is relatively stable, and the Protodyakonov hardness coefficient of the coal is f = 0.3, making it a mineable coal seam in the entire area.

[0064] In this embodiment, the working face has a mining length of 855m, the coal mining unit 061 has a width of 5m, and there are a total of 171 coal mining units 061.

[0065] The mining process in this embodiment is as follows: Figure 13 As shown:

[0066] S1, based on existing engineering geological data, plans the working face and coal mining unit 061 for coal mining operations;

[0067] S11, plan the working face, determine the location of the upper roadway 021, lower roadway 022 and roadway connecting roadway 023, open the upper roadway 021 and lower roadway 022 along the working face, one end of the upper roadway 021 and lower roadway 022 respectively connects to the mining area transport roadway 02, and the other end of the upper roadway 021 and lower roadway 022 respectively connects to the roadway connecting roadway 023. Open a return air shaft 03 between the roadway connecting roadway 023 and the surface 01, or open a dedicated return air roadway 024 to connect to the mining area return air roadway 07. Open a hidden shaft 025 or a hidden inclined shaft connecting the dedicated return air roadway 024 and the roadway connecting roadway 023.

[0068] like Figure 1 and 2 As shown in the figure, the gray blocks represent the black coal seam 06 (the same applies below). In this embodiment, both the upper roadway 021 and the lower roadway 022 are intake airways. The airflow passes through the roadway connecting roadway 023 and finally converges at the dark vertical shaft 025, then flows through the dedicated return airway 024 to the mining area return airway 07.

[0069] The cross-sectional shape, dimensions, support methods, and support parameters of the upper roadway 021, lower roadway 022, roadway connecting roadway 023, dedicated return airway 024, and the underground shaft 025 connecting the dedicated return airway 024 and the upper and lower roadway connecting roadways are designed. Based on the mechanical properties and stress field properties of coal seam 06, its roof, and floor, the strength of the roof, safety coal pillar 04 of the roadway connecting roadway, safety coal pillar 05 of the mining area haulage roadway, and roadway support of coal mining unit 061 are checked using the "Elastic-Plastic Theory." Based on the check results, the width of coal mining unit 061, the width of safety coal pillar 04 of the roadway connecting roadway, the width of safety coal pillar 05 of the mining area haulage roadway, and roadway support parameters are adjusted accordingly.

[0070] S12, In this embodiment, the 11802 working face is divided into 171 coal mining units 061, each coal mining unit 061 is 5m wide, and is divided into 2 large groups, as follows: Figure 3 and Figure 4 As shown. Coal mining unit 061 in the first large group is marked with ①, and coal mining unit 061 in the second large group is marked with ②. The first large group is mined first, and after the first large group is completed, the second large group is mined. The mined units in the first large group must be backfilled immediately after mining is completed. After the mining of coal mining unit 061 in the second large group is completed, the upper and lower ends of coal mining unit 061 must be sealed. The seal must be tight, and there must be no gaps for gas leakage. Coal mining unit 061 in each large group needs to be further divided into several small groups, and then the mining sequence is determined.

[0071] The lower feed groove 022 of the previous working face can be used as the upper feed groove 021 of the next adjacent working face. Only the first working face needs to be set with two feed grooves, and subsequent working faces only need to be set with one feed groove. The lower feed groove 022 of the previous working face can be used as the upper feed groove 021 of the next working face.

[0072] The dedicated return airway 024 and the underground vertical shaft 025 not only serve as dedicated return air passages for this working face, but also continue to serve as dedicated return air passages for the next working face, such as... Figure 5 and 6 As shown. After the previous working face is mined and backfilled, two locations are sealed off with sealing walls 026: the junction between the main haulage roadway 02 of the mining area and the upper roadway 021 of the previous working face, and the upper side of the underground shaft 025 in the roadway connecting roadway 023. Then, the dedicated return airway 024 and the underground shaft 025 naturally become the dedicated return air ducts for the next working face. The air from the upper roadway 021 and lower roadway 022 of the next working face can flow to the main return airway 07 of the mining area through the underground shaft 025 and the dedicated return airway 024. Therefore... Figure 2 The dedicated return airway 024 and the underground shaft 025 can also serve as dedicated return airways for the next working face and several subsequent working faces.

[0073] S2, a coal cutting hole 10 and a gas drainage hole 11 are opened in the planned coal mining unit 061 for coal mining, and a coal chute 12 is opened at the lower end of the coal mining unit 061; the specific process is as follows:

[0074] Step S21: Based on the thickness of coal seam 06 and the width of coal mining unit 061, determine the opening position and diameter of the cutting hole 10 on the cross-section of coal mining unit 061. The cut-off position of the cutting hole 10 is located at the coal chute 12 at the lower end of coal mining unit 061, that is, the cutting hole 10 is connected to the coal chute 12. The cutting hole 10 is parallel to the axis of coal mining unit 061. Using the determined opening position of the cutting hole 10 in coal mining unit 061, the cut-off position of the cutting hole 10, and the parallel relationship between the cutting hole 10 and the axis of coal mining unit 061, the cutting hole 10 is drilled in coal mining unit 061. At the same time, the specifications of the sleeve placed inside the cutting hole 10 are determined.

[0075] The coal cutting hole 10 is located on the vertical symmetry line of the cross-section of coal mining unit 061, below the horizontal symmetry line of the cross-section of coal mining unit 061. The gas drainage hole 11 is located on one side (left or right) of the vertical symmetry line of the cross-section of coal mining unit 061, above the horizontal symmetry line of the cross-section of coal mining unit 061. Figure 7As shown in the figure, h is the height of coal mining unit 061, and a is the width of coal mining unit 061. A PVC or fiberglass sleeve is installed inside the coal cutting hole 10. The gas extraction hole 11 also serves as a coal flushing hole, with a steel screen pipe 13 inside. Numerous round holes for ventilation are drilled at certain intervals along the longitudinal direction of the steel screen pipe 13, with a diameter of 15mm.

[0076] Step S22: After the coal cutting hole 10 is formed, the sleeves are connected and lowered one by one from the upper end of the coal cutting hole 10 until they are lowered to the bottom end of the coal cutting hole 10, that is, the coal chute 12.

[0077] Step S23: After the sleeve is in place, secure the sleeve at the upper end.

[0078] Step S24: Determine the opening position and diameter of the gas drainage hole 11 on the cross-section of the coal mining unit 061 based on the thickness of the coal seam 06. The cut-off position of the gas drainage hole 11 is located at the coal chute 12 at the lower end of the coal mining unit 061, that is, the gas drainage hole 11 is connected to the coal chute 12. The gas drainage hole 11 is parallel to the axis of the coal mining unit 061. Using the determined opening position of the gas drainage hole 11 on the coal mining unit 061, the cut-off position of the gas drainage hole 11, and the parallel relationship between the gas drainage hole 11 and the axis of the coal mining unit 061, the gas drainage hole 11 is drilled in the coal mining unit 061. At the same time, the specifications of the steel screen pipe 13 placed in the gas drainage hole 11 are determined.

[0079] Step S25: After the gas drainage hole 11 is formed, steel screen pipes 13 are connected and lowered one by one from the upper end of the gas drainage hole 11 until they are lowered to the bottom end of the gas drainage hole 11, that is, the coal chute 12.

[0080] Step S26: After the steel screen tube 13 is in place, the steel screen tube 13 is fixed at the upper end.

[0081] like Figure 8 and Figure 9 As shown, gas is extracted during coal mining and backfilling. The extracted gas is a mixture of gas and air, 30. The upper end of the steel screen pipe 13 is connected to the negative pressure gas extraction pipe 132 and the high-pressure water supply pipe 133 via a tee 131, and is controlled by valves.

[0082] The process of setting up the coal chute 12 in step S2 is as follows:

[0083] Step S27, as Figure 10As shown, a coal chute 12 is excavated between the bottom of the coal mining unit 061 and the lower roadway 022, connecting to the lower roadway 022. The bottom plate of the coal chute 12 is at the same horizontal elevation as the bottom plate of the lower roadway 022. The width of the coal chute 12 is 1.5m smaller than the width of the coal mining unit 061, the height of the coal chute 12 is 2.5m, and the depth of the coal chute 12 is 2m.

[0084] Step S28: The roof and side walls of the coal chute 12 are supported by anchor mesh cable spraying support method;

[0085] Step S29: A coal receiving chute 14 is set inside the coal chute 12. The upper end of the coal receiving chute 14 is set below the lower port of the coal mining unit 061. The inclination angle of the coal receiving chute 14 is less than the inclination angle of the bottom plate of the coal seam 06.

[0086] like Figure 11 As shown, the coal receiving chute 14 includes a chute bottom plate 141, a coal retaining plate 142, and a column leg 143. The coal retaining plate 142 is welded to both sides of the chute bottom plate 141. The chute bottom plate 141 is inclined at an angle of 20°. The upper end of the chute bottom plate 141 is close to the coal mining unit 061. The chute bottom plate 141 is trapezoidal. The short bottom edge of the trapezoid is close to the lower roadway 022, and the long bottom edge of the trapezoid is close to the coal mining unit 061. The column leg 143 is fixed to the bottom of the chute bottom plate 141.

[0087] The trapezoidal chute bottom plate 141 has a short base length of 1500mm and a long base length of 2500mm. Its height is 1200mm on the side near coal mining unit 061 and 500mm on the side near the lower chute 022. The chute bottom plate 141 is supported by a steel plate with a thickness of not less than 10mm. The coal retaining plate 142 has a height of 300mm and a thickness of 8mm. The coal receiving chute 14 has five columns 143, which are round steel pipes with an outer diameter of 150mm and a wall thickness of 8mm. One column 143 is located at the centroid of the chute bottom plate 141.

[0088] S3, mining of coal unit 061, while using small mining drones to monitor the coal mining process and the conditions of the roof and bottom of goaf 08.

[0089] The mining process of coal mining unit 061 is as follows:

[0090] Step S31: Connect the cutting gun 15 for coal mining to the drilling device 09 through the high-pressure water conveying drill rod 151. Add a high-pressure water rotary joint 152 between the drilling device 09 and the high-pressure water conveying drill rod 151. Connect the high-pressure water rotary joint 152 to the high-pressure water pump 153 through a high-pressure water pipe 154.

[0091] In step S32, the rotation of the cutting gun is driven by the high-pressure water conveying drill rod 151. The rotation of the high-pressure water conveying drill rod 151 originates from the drilling device 09, but the high-pressure water rotary joint 152 does not move with the high-pressure water conveying drill rod 151. Therefore, while the high-pressure water conveying drill rod 151 is rotating, the high-pressure water pump 153 can continuously supply high-pressure water to the high-pressure water conveying drill rod 151 through the high-pressure water connecting pipe and the high-pressure water rotary joint 152, and finally emit a high-pressure water jet through the water spray hole of the cutting gun 15 to cut and crush coal.

[0092] In step S33, the cutting gun 15 rotates under the drive of the drilling device 09 and retreats along the casing at set time intervals. As the cutting gun 15 rotates and retreats, it performs high-pressure water jet rotation and retreat coal mining. Under the action of the high-pressure water jet, the casing is quickly cut, and the coal seam 06 around the casing is shredded and falls down, forming a water-coal flow that flows towards the coal chute 12 under the action of the water flow.

[0093] Step S34: Use a small mining drone to monitor various conditions of the goaf, such as the high-pressure water jet rotary cutting and crushing process, the surrounding rock conditions of the goaf 08, the flow of water and coal, and whether there is siltation on the floor of the goaf 08.

[0094] In this embodiment, the cutting gun 15 used for spraying high-pressure water jets has eight spray holes arranged in four rows; each row has two holes, arranged along the radial line, with a position difference of 180°; the axes of the four spray holes in the first and fourth rows are perpendicular to the axis of the cutting gun, the axis of the holes in the second row forms a 70° angle with the axis of the cutting gun, and the angle faces the front end of the cutting gun; the two spray holes in the third row form an 80° angle with the axis of the cutting gun, and the angle faces the front end of the cutting gun. The structure of the cutting gun 15 is as follows. Figure 12 As shown.

[0095] In this embodiment, the high-pressure water pump 153 generates a water pressure of 25 MPa, and the drilling device 09 rotates at a speed of 40 rpm. Along the axial direction of the coal mining unit 061, the cutting gun 15 cuts 1000 mm of coal each time. The cutting gun 15 retracts 1000 mm each time along the axial direction of the coal mining unit 061. Along the axial direction of the coal mining unit 061, the cutting gun 15 cuts coal at a fixed position for 35 minutes.

[0096] In this embodiment, the small mining drone has a waterproof fog function. In addition to normal high-definition video recording, its camera also needs to have an infrared video recording function to ensure that it can monitor the condition of the goaf 08 and the coal cutting situation of the cutting gun 15 when the water fog is dense.

[0097] S4, performs coal-water separation on the mined coal-water stream;

[0098] The coal-water separation process of the coal-water stream is as follows:

[0099] In step S41, the coal receiving chute 14 is set inside the coal chute 12. A scraper conveyor 16, a vertical elevator 17, a dewatering vibrating screen 19, a belt conveyor 18, and a deflector plate 20 are set inside the lower roadway 022. One end of the coal receiving chute 14 is close to the lower port of the coal mining unit 061, and the other end is connected to the scraper conveyor 16. One end of the scraper conveyor 16 is located below the coal receiving chute 14, and the other end is close to the lower side of the vertical elevator 17. The vertical elevator 17 is close to the belt conveyor 18, and the upper horizontal portion of the vertical elevator 17 is located above the dewatering vibrating screen 19. The dewatering vibrating screen 19 is located above the belt conveyor 18, and the deflector plate 20 is set between the dewatering vibrating screen 19 and the belt conveyor 18.

[0100] The bottom plate of the lower chute 022 is provided with a slight slope along the transverse direction, with an angle of 2°-3°. The bottom plate of the lower chute 022 on the side of the water ditch 21 is lower, and the bottom plate of the lower chute 022 on the side of the belt conveyor 18 is higher. The purpose is to guide the water dewatered by the dewatering vibrating screen 19 into the water ditch 21, and then flow to the sedimentation tank for sedimentation before being reused for cutting coal by the cutting gun 15, thus realizing the recycling of water.

[0101] In step S42, the shredded coal cut by the cutting gun 15 is mixed with water to form a coal-water flow. After the coal-water flow flows out of the coal mining unit 061, it is buffered by the coal receiving chute 14 and falls onto the scraper conveyor 16. The scraper conveyor 16 directly sends the transferred coal-water flow into the vertical elevator 17. The vertical elevator 17 transfers the coal-water flow to the dewatering vibrating screen 19 set above the belt conveyor 18.

[0102] In step S43, the coal and water flow enters the dewatering vibrating screen 19 and is dewatered. The dewatered coal falls directly onto the belt conveyor 18, while the dewatered water falls directly onto the water-repellent plate 20 from below the dewatering vibrating screen 19. The water is guided by the water-repellent plate 20 to the outside of the belt conveyor 18 and finally flows into the ditch 21 on the other side.

[0103] In this embodiment, the scraper conveyor 16 can be a single scraper conveyor 16, or two scraper conveyors 16 can be placed side by side to form a combined scraper conveyor 16. The feed inlet width of the vertical elevator 17 should be greater than the width of the scraper conveyor 16. The conveying capacity of the belt conveyor 18 should be greater than the dewatering and conveying capacity of the dewatering vibrating screen 19. The dewatering and conveying capacity of the dewatering vibrating screen 19 should be greater than the lifting capacity of the vertical elevator 17. The lifting capacity of the vertical elevator 17 should be greater than the conveying capacity of the scraper conveyor. The conveying capacity of the scraper conveyor should be greater than the transfer capacity of the coal receiving chute 14.

[0104] S5 involves backfilling the goaf 08 formed after coal mining. The specific process is as follows:

[0105] Step S51: Use 6mm thick steel plates and I-beams to make grid-like side protection plates, and use single pillars for support so that the side protection plates are tightly attached to the outer wall of the coal chute 12, that is, one side of the lower roadway 022. The side protection plates should have high resistance to lateral pressure to prevent the side explosion accident during the filling process of the coal chute 12.

[0106] Step S52: Insert a return slurry pipe into the side plate at the upper edge of the coal chute 12 to monitor whether the coal chute 12 has been filled tightly. The return slurry pipe is a sheet metal pipe or a PVC pipe.

[0107] Step S53: Inorganic grouting material is used to fill the coal chute 12. The filling material is injected from the upper port of the coal mining unit 061 and flows down the inclined bottom plate of the goaf 08 of the coal mining unit 061 until the coal chute 12.

[0108] Step S54: The filling material of the coal chute 12 can be used to fill the goaf 08 only after it reaches 20MPa. At the end of each continuous filling, the steel screen pipe 13 must be quickly flushed with water to prevent it from becoming blocked and to facilitate the extraction of gas from the steel screen pipe 13.

[0109] The grouting material used for filling coal chute 12 and the grouting material used in the 10m area of ​​goaf 08 adjacent to coal chute 12 are different from the grouting materials used in the rest of goaf 08. The grouting material used for filling coal chute 12 and the grouting material used in the 10m area of ​​goaf 08 adjacent to coal chute 12 need to have high strength and rapid setting properties, and the 24-hour compressive strength should be above 20MPa, so as to meet the requirements of timely, rapid and continuous filling of subsequent goaf 08.

[0110] To prevent the collapse of the protective plate, the grouting material used for filling the coal chute 12 and the 10m area of ​​the goaf 08 near the coal chute 12 can be filled in 2-3 times; the 28-day uniaxial compressive strength of the inorganic grout must be higher than the uniaxial compressive strength of the coal body.

[0111] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A green mining method for unmanned coal face using high-pressure water jet rotary cutting and crushing in steeply inclined coal seams, characterized in that: Includes the following steps: S1, based on engineering geological data, plans the working face and coal mining unit for coal mining operations; S11, plan the working face, determine the location of the upper roadway, lower roadway and roadway connecting roadway, open the upper roadway and lower roadway along the working face, one end of the upper roadway and lower roadway respectively connects to the mining area transport roadway, the other end of the upper roadway and lower roadway respectively connects to the roadway connecting roadway, open a return air shaft between the roadway connecting roadway and the surface, or open a dedicated return air roadway to connect to the mining area return air roadway, open a hidden shaft or hidden inclined shaft connecting the dedicated return air roadway and the roadway connecting roadway; S12 divides a working face into multiple strip-shaped coal mining units. The number of mining groups is determined according to the coal seam conditions and the number of coal mining units. According to the principle of skip mining, the coal mining units in each group are not adjacent to each other. The coal mining units in the same group are numbered with a unified number. Each group of coal mining units is divided into multiple subgroups. The coal mining units in each subgroup carry out mining operations simultaneously. S2, In the planned coal mining unit, coal cutting holes and gas drainage holes are opened for coal mining, and a coal chute is opened at the lower end of the coal mining unit; S3 is used for mining in coal mining units, while simultaneously monitoring the mining process and the conditions of the roof, walls, and floor of the goaf. S4, which separates coal and water in the mined coal-water stream and recycles the separated water; S5, backfilling the goaf formed after coal mining; In step S11, both the upper and lower roadways are air intake roadways. The airflow passes through the roadway connecting roadway and finally gathers at the return air shaft, and is discharged to the ground through the return air shaft. If a return air shaft is not set up, a dedicated return air roadway must be set up. A hidden shaft or a hidden inclined shaft is set up between the dedicated return air roadway and the connecting roadway of the roadway. The airflow from the upper roadway and the lower roadway gathers at the hidden shaft or the hidden inclined shaft and flows to the dedicated return air roadway through the hidden shaft or the hidden inclined shaft, and enters the main return air roadway of the mining area through the dedicated return air roadway. In step S11, the lower feed groove of the previous working face is used as the upper feed groove of the next adjacent working face. Only the first working face needs to be set with two feed grooves, and subsequent working faces only need to be set with one feed groove. The lower feed groove of the previous working face can be used as the upper feed groove of the next working face. Return air shafts or dedicated return air roadways and underground shafts are not only used as return air passages for this working face, but also continue to be used as dedicated return air passages for the next working face. As long as the connecting roadways of the upper and lower working faces are connected to each other, the airflow will naturally flow to the return air shaft and discharge to the surface, or flow to the underground shaft or underground inclined shaft and enter the main return air roadway of the mining area through the dedicated return air roadway.

2. The green mining method for unmanned coal face using high-pressure water jet rotary cutting and crushing in steeply inclined coal seams according to claim 1, characterized in that, In step S11, the large-diameter return air shaft between the roadway connecting roadway and the ground is replaced by several small-diameter vertical air ducts that go directly to the ground.

3. The green mining method for unmanned coal face using high-pressure water jet rotary cutting and crushing in steeply inclined coal seams according to claim 1, characterized in that, The process of setting up the coal cutting hole and gas drainage hole in step S2 is as follows: Step S21: Determine the opening position and diameter of the coal cutting hole on the cross-section of the coal mining unit based on the coal seam thickness and the width of the coal mining unit. The cut-off position of the coal cutting hole is located at the coal chute at the lower end of the coal mining unit, that is, the coal cutting hole is connected to the coal chute. The coal cutting hole is parallel to the axis of the coal mining unit. Based on the determined opening position, opening cut-off position and parallel relationship between the coal cutting hole and the axis of the coal mining unit, drill the coal cutting hole in the coal mining unit using a drilling device, and at the same time determine the specifications of the casing placed inside the coal cutting hole. Step S22: After the coal cutting hole is formed, the sleeves are connected and lowered one by one from the top of the coal cutting hole until they are lowered to the bottom of the coal cutting hole, i.e., the coal chute. Step S23: After the sleeve is in place, secure the sleeve at the upper end. Step S24: Determine the opening position and diameter of the gas drainage hole on the cross-section of the coal mining unit based on the coal seam thickness and the width of the coal mining unit. The cut-off position of the gas drainage hole is located at the coal chute at the lower end of the coal mining unit, that is, the gas drainage hole connects to the coal chute. The gas drainage hole is parallel to the axis of the coal mining unit. Based on the determined opening position and cut-off position of the gas drainage hole on the coal mining unit, as well as the parallel relationship between the gas drainage hole and the axis of the coal mining unit, drill the gas drainage hole in the coal mining unit, and at the same time determine the specifications of the steel screen pipe placed in the gas drainage hole. Step S25: After the gas drainage hole is formed, steel screen pipes are connected and lowered one by one from the top of the gas drainage hole until they are lowered to the bottom of the gas drainage hole, i.e., the coal chute. Step S26: After the steel screen tube is in place, fix the steel screen tube at the upper end.

4. The green mining method for unmanned mining faces of steeply inclined coal seams using high-pressure water jet rotary cutting and crushing as described in claim 3, is characterized in that... The process of setting up the coal chute in step S2 is as follows: Step S27: A coal chute is excavated between the bottom of the coal mining unit and the lower roadway to connect with the lower roadway. The bottom plate of the coal chute and the bottom plate of the lower roadway are at the same elevation. Step S28: The roof and side walls of the coal chute are supported using the anchor mesh cable spraying support method. Step S29: A coal receiving chute is set inside the coal chute. The upper end of the coal receiving chute is located below the lower port of the coal mining unit, and the inclination angle of the coal receiving chute is smaller than the inclination angle of the coal seam floor.

5. The green mining method for unmanned coal face using high-pressure water jet rotary cutting and crushing in steeply inclined coal seams according to claim 4, characterized in that, The coal receiving chute includes a chute bottom plate, a coal retaining plate, and column legs. The coal retaining plate is welded to both sides of the chute bottom plate. The chute bottom plate is inclined at an angle of 15°-30°. The upper end of the chute bottom plate is close to the lower port of the coal mining unit and lower than the lower edge of the lower port of the coal mining unit. The chute bottom plate is trapezoidal, with the shorter base of the trapezoid close to the lower feed roadway and the longer base of the trapezoid close to the coal mining unit. The column legs are fixed to the bottom of the chute bottom plate.

6. The green mining method for unmanned coal face using high-pressure water jet rotary cutting and crushing in steeply inclined coal seams according to claim 3, characterized in that, In step S3, the mining process of the coal mining unit is as follows: Step S31: Connect the cutting gun used for coal mining to the high-pressure water conveyance drill rod, and lower the cutting gun along the casing to the end of the casing through the drilling device; Step S32: After the cutting gun is lowered into place with the drilling device, a set of high-pressure water rotary joints is added between the drilling device and the high-pressure water conveyance drill rod. The high-pressure water rotary joints are connected to the high-pressure water pump. When the high-pressure water pump is working, the water outlet of the cutting gun sprays out a high-pressure water jet. The drilling device drives the cutting gun to rotate, and the cutting gun starts to rotate and cut and crush coal through the high-pressure water jet. In step S33, the cutting gun rotates under the drive of the drilling device and retreats along the casing at set time intervals. As the cutting gun rotates and retreats, it performs high-pressure water jet rotation and retreat coal mining. Under the action of the high-pressure water jet, the casing is quickly cut, and the coal seam around the casing is shredded and falls down, forming a water-coal flow that flows towards the coal chute under the action of the water flow. Step S34: Use a small mining drone to monitor the high-pressure water jet rotary cutting and crushing process, the surrounding rock conditions of the goaf, the flow of water and coal, and whether there is any blockage in the goaf floor.

7. The green mining method for unmanned mining faces of steeply inclined coal seams using high-pressure water jet rotary cutting and crushing as described in claim 6, is characterized in that... The coal-water separation process in step S4 is as follows: Step S41: The coal receiving chute is set inside the coal chute opening. A scraper conveyor, a vertical elevator, a dewatering vibrating screen, a belt conveyor, and a deflector are set inside the lower chute. One end of the coal receiving chute is close to the lower port of the coal mining unit, and the other end is connected to the scraper conveyor. One end of the scraper conveyor is located below the coal receiving chute, and the other end is close to the lower side of the vertical elevator. The vertical elevator is close to the belt conveyor, and the upper horizontal part of the vertical elevator is located above the dewatering vibrating screen. The dewatering vibrating screen is located above the belt conveyor, and the deflector is set between the dewatering vibrating screen and the belt conveyor. In step S42, the shredded coal cut by the cutting gun is mixed with water to form a coal-water flow. After the coal-water flow flows out of the coal mining unit, it is buffered by the coal receiving chute and falls onto the scraper conveyor. The scraper conveyor directly sends the transferred coal-water flow into the vertical elevator. The vertical elevator transfers the coal-water flow to the dewatering vibrating screen set above the belt conveyor. In step S43, the coal and water flow enters the dewatering vibrating screen and is dewatered. The dewatered coal falls directly onto the belt conveyor and is sent away. The dewatered water falls directly onto the water-repellent plate from below the dewatering vibrating screen, is guided by the water-repellent plate to one side of the belt conveyor, and finally flows into the ditch on the other side of the downward channel.

8. The green mining method for unmanned coal face using high-pressure water jet rotary cutting and crushing in steeply inclined coal seams according to claim 6, characterized in that, The process of filling the goaf in step S5 is as follows: Step S51: Use steel plates and I-beams to make grid-like side protection plates, and use single pillars for support so that the side protection plates are tightly attached to the outer wall of the coal chute, that is, one side of the lower chute. Step S52: Insert a return grout pipe into the side plate at the upper edge of the coal chute to monitor whether the coal chute has been filled and compacted during the grouting process. Step S53: Inorganic grouting material is used to fill the coal chute. The filling material is injected from the upper end of the coal mining unit and flows down the inclined bottom plate until it reaches the coal chute. Step S54: Goaf filling can only be carried out after the filling material at the coal chute reaches 20MPa. At the end of each continuous filling, the steel screen pipe must be quickly flushed with water to facilitate the extraction of gas from the steel screen pipe.

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