CN116122813A - Underground physical fluidization coal mining system and coal mining method - Google Patents

Abstract

The invention discloses an underground physical fluidization coal mining system and a coal mining method, wherein the coal mining system comprises a fluidization drilling gas-coal simultaneous mining part and a coal mining cave filling part; the coal mining method comprises drilling construction, fluidized gas and coal simultaneous mining and coal mining cave filling. The invention adopts an ascending hole mode to carry out coal mining operation, forms high-pressure water jet flow through the injection device and the extension device, and realizes in-situ crushing and cutting of coal bodies by matching with the rotation of the high-pressure sealing drill rod, and adopts the orifice sealing unit and the water-coal separating unit to separate and recycle coal and gas from crushed coal particle-water-gas mixtures, and finally fills coal mining cavities, thereby realizing safe, efficient and green coal resource exploitation. The invention can complete safe and efficient mining operation of difficult-to-mine (carry-over) coal resources such as corner coal, chicken nest coal, geology complex coal seam, thin coal seam, steeply inclined coal seam, carry-over coal pillar and the like, and is particularly suitable for mining inclined soft coal seam.

Description

Underground physical fluidization coal mining system and coal mining method

Technical Field

The invention relates to an underground coal mining system and a coal mining method of a coal mine, in particular to an underground physical fluidization coal mining system and a safe and efficient fluidization coal mining method which are suitable for various mines, particularly suitable for mining difficult-to-mine (legacy) coal resources such as corner coal, litter coal, geology complex coal seams, thin coal seams, steeply inclined coal seams, legacy coal pillars and the like, and belongs to the technical field of coal mining.

Background

The 'gas deficiency, oil deficiency and coal enrichment' are basic patterns of the energy system in China. In the face of complex and changeable domestic and foreign situations, coal is still a main energy source of China for a long time, plays roles of a stabilizer and a ballast stone in national energy safety and economic high-quality development, and is also an important guarantee for supporting carbon neutralization target realization of China. Research shows that the coal yield in China reaches a peak value in fourteen-five periods, but the coal yield of the current underground mining is only 30% -40%, and great resource waste is caused. According to statistics, the amount of difficult-to-collect (carry-over) coal resources occurring in mines in China is up to 420 hundred million tons, and the difficult-to-collect (carry-over) coal resources mainly comprise corner coal, chicken nest coal, geology complex coal seams, thin coal seams, steeply inclined coal seams, carry-over coal pillars and the like. Therefore, the development of the difficult-to-collect (carry-over) coal resource is very important for improving the productivity of the coal mine, releasing the surplus productivity and ensuring the energy stability of China.

At present, the mining method of the difficult-to-mine (carry-over) coal resources still mainly adopts mining technology of arranging a stope face, and all the mining methods face unavoidable problems. The corner coal is left by underground mining, fully-mechanized mining equipment cannot be arranged due to the large shape and coal thickness change, and the safe and efficient mining technology does not exist at present, so that the coal is generally selected and abandoned. For the thin coal seam and the steeply inclined coal seam, due to the characteristics of occurrence of the thin coal seam and the steeply inclined coal seam, the coal mining space is limited, the conventional fully-mechanized mining equipment is difficult to arrange, the safety coefficient is low, the mechanical degree is low, the labor intensity is high, the work efficiency is low in the mining process, and further the cost input for mining the thin coal seam and the steeply inclined coal seam is excessive, and most coal mine enterprises choose to abandon mining. In summary, for difficult-to-mine (carry-over) coal resources such as corner coal, chicken nest coal and geology complex coal seam, adopting a mode of arranging a stoping working face to mine faces a series of problems such as high cost, low efficiency, high risk, poor flexibility, incapability of exerting technical advantages of mechanized mining and the like, so that the underground mining technology cannot safely and efficiently mine the difficult-to-mine (carry-over) coal resources, and a novel mining mode is urgently needed to realize safe and efficient mining operation of the difficult-to-mine (carry-over) coal resources.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides an underground physical fluidization coal mining system and a coal mining method, which can realize safe and efficient mining of difficult-to-mine (carry-over) coal resources such as corner coal, chicken nest coal, geology complex coal seam, thin coal seam, steeply inclined coal seam, carry-over coal pillar and the like, and are particularly suitable for mining inclined soft coal seam with coal seam inclination angle.

In order to achieve the purpose, the underground physical fluidization coal mining system comprises a fluidization drilling gas-coal simultaneous mining part, wherein the fluidization drilling gas-coal simultaneous mining part comprises a jet coal breaking unit, an orifice sealing unit and a water-coal separation unit;

the jet coal breaking unit comprises a coal breaking drill bit, a spraying device, an extending device, a high-pressure sealing drill rod, a high-pressure water tail, a drilling machine and a high-pressure water pump; the high-pressure sealing drill rod is of a cylindrical structure with consistent outer diameter and multiple sections of airtight installation connection, and a hollow water passage is arranged in the high-pressure sealing drill rod; the foremost end of the high-pressure sealing drill rod is hermetically provided with a connecting and stretching device, and the rearmost end of the high-pressure sealing drill rod is hermetically provided with a connecting and stretching device; the front end of the stretching device is hermetically provided with a spraying device, and the front end of the spraying device is in threaded connection with a coal breaking drill bit; the high-pressure water output end of the high-pressure water pump can be in airtight installation connection with the high-pressure water tail through a pipeline; the drilling machine is in transmission connection with the high-pressure sealing drill rod;

the high-pressure sealing drill rod can pass through the orifice sealing unit along the front-back axial direction of the orifice sealing unit, a coal water passing channel is formed between the outer surface of the high-pressure sealing drill rod and the inner surface of the front sealing sleeve, and a supporting sealing ring which is in sealing fit with the outer diameter of the high-pressure sealing drill rod and is used for sealing and supporting the high-pressure sealing drill rod is coaxially and fixedly arranged in the rear sealing sleeve; the sealing unit main body is of a container structure with a large-volume inner cavity, the top end of the sealing unit main body is provided with a gas outlet communicated with the inner cavity of the sealing unit main body, the gas outlet is communicated with the mine gas pumping pipe in a sealing way through a pipeline, the bottom end of the sealing unit main body is provided with a water-coal outlet communicated with the inner cavity of the sealing unit main body, and the water-coal outlet is connected with the input end of the coal-water collecting box through a pipeline; the output end of the coal water collecting box (6) is connected with the input end of the slurry conveying pump through a pipeline.

The water-coal separation unit comprises a vibrating screen, a scraper conveyor, a sedimentation tank and a filter press; the outlet of the slurry conveying pump output end connecting pipeline is arranged above the material input end of the vibrating screen, the material output end of the vibrating screen is arranged above the material input end of the scraper conveyor, the sedimentation tank comprises a primary sedimentation tank and a secondary filtering tank, the vibration dehydration water outlet of the vibrating screen is connected with the primary sedimentation tank through a pipeline, the sludge pump of the material input end of the filter press is arranged in the primary sedimentation tank, the filter pressing water outlet of the filter press is connected with the secondary filtering tank through a pipeline, and the input end of the high-pressure water pump is connected with the secondary filtering tank through a pipeline.

As a further improvement of the invention, the underground physical fluidization coal mining system further comprises a coal mining cave filling part, wherein the coal mining cave filling part comprises a pulping device and a pumping pressure filling device, the pulping device comprises a crusher, a sieving machine, a stirrer and a feeder, and the pumping pressure filling device comprises a filling pump and a filling pipeline.

As a further improvement scheme of the invention, the spraying device is provided with 1-8 jet nozzles, the spraying direction of the jet nozzles and the axial direction of the spraying device form an included angle of 45-90 degrees, a plurality of jet nozzles are uniformly distributed along the circumferential direction of the spraying device, and/or a plurality of jet nozzles are uniformly distributed along the axial direction of the spraying device.

As a further improvement scheme of the invention, the stretching device is provided with a plurality of diameter-expanding swing arms which are symmetrically arranged relative to the center of the base body, the length of the diameter-expanding swing arms is 0.5-2.5 m, the diameter-expanding swing arms can radially stretch along the drill rod through a center rotating shaft, drainage channels are arranged in the diameter-expanding swing arms and the base body, and the diameter-expanding swing arms and the base body are matched with jet nozzles arranged in front of the swing arms to generate high-pressure water jet.

As a further development of the invention, the support sealing rings are arranged in at least two groups in the axial direction of the rear sealing sleeve.

The coal mining method based on the underground physical fluidization coal mining system specifically comprises the following steps:

step one, drilling construction: the coal breaking drill bit is arranged at the front end of the high-pressure sealing drill rod, the high-pressure water tail is arranged at the rear end of the high-pressure sealing drill rod, and the drilling machine is utilized to drive the high-pressure sealing drill rod to drill upwards for 2-4 m along a coal seam and then stop drilling; withdrawing the high-pressure sealing drill rod and the coal breaking drill bit, replacing the coal breaking drill bit with a reaming drill bit to ream the hole opening of the drilled hole, wherein the reaming inner diameter is larger than the outer diameter of the front sealing sleeve; a front sealing sleeve is put in a reaming position, grouting is carried out in an annulus between a drilling hole and the front sealing sleeve to fix the front sealing sleeve, then a sealing unit main body and a rear sealing sleeve are coaxially and hermetically and fixedly arranged on the front sealing sleeve, a gas outlet is hermetically and fixedly arranged with a mine gas pumping pipe through a pipeline, and a water-coal outlet is connected with the input end of a coal-water collecting box through a pipeline; replacing the reaming bit with a coal breaking bit, enabling the high-pressure sealing drill rod and the coal breaking bit to pass through the orifice sealing unit, driving the high-pressure sealing drill rod to continuously drill forwards to a set distance by using the drilling machine, stopping drilling, withdrawing the high-pressure sealing drill rod and the coal breaking bit, and finishing coal mining drilling construction;

step two, fluidized gas coal simultaneous mining: the stretching device, the spraying device and the coal breaking drill bit are sequentially arranged at the front end of the high-pressure sealing drill rod, and the high-pressure sealing drill rod, the stretching device, the spraying device and the coal breaking drill bit penetrate through the orifice sealing unit and extend into the hole bottom position of the coal mining drill hole; starting a high-pressure water pump, controlling a high-pressure sealing drill rod to rotate at a proper rotating speed through a drilling machine to perform hydraulic coal breaking, enabling a broken coal body to flow back to the inner cavity of the sealing unit main body along with water flowing through an annular space between a drilling hole and the high-pressure sealing drill rod, enabling the broken coal body to flow into a collecting box through a water-coal outlet, finally conveying and pumping the broken coal body to a water-coal separation unit through slag slurry, enabling gas released by the broken coal body to flow into the inner cavity of the sealing unit main body through the annular space between the drilling hole and the high-pressure sealing drill rod, and enabling the broken coal body to enter a mine gas pumping pipe through a gas outlet; adopting a stepping backward type coal mining mode, controlling the high-pressure sealing drill rod to move back and forth within a set range until the coal yield of a drilled hole is greatly reduced, then controlling the high-pressure sealing drill rod to backward set step distance, and performing 'backward-coal breaking-backward-coal breaking' cyclic work by analogy until an extension device, a spraying device and a coal breaking drill head approach an orifice sealing unit, so as to finish the exploitation of coal bodies around the drilled hole;

step three, drilling and filling: and forming a drilling coal mining cave in the process of retreating the high-pressure sealing drill rod, grouting and filling the drilling coal mining cave after all coals around the drilling hole are extracted, forming a drilling filling area after grouting the whole drilling coal mining cave, arranging other coal mining holes at intervals for continuous physical fluidization coal mining after grouting to form the drilling filling area, and arranging the coal mining holes in the adjacent area of the drilling filling area for physical fluidization coal mining after filling slurry in the drilling filling area is solidified.

As a further improvement of the invention, the coal mining process in each set step is as follows: firstly, setting a high-pressure water pump to work within the pressure range of 8-15 MPa, enabling high-pressure water to flow out completely through a jet nozzle of a jet device, and cutting and crushing coal bodies in the step distance; when the coal output in the working state is greatly reduced, the working pressure of the high-pressure water pump is increased to be more than 15MPa, so that the high-pressure water flows out through the jet nozzle of the stretching device, the coal in the step is cut and crushed continuously until the coal output of the drill hole is greatly reduced again, and the fluidized gas-coal simultaneous mining operation in the step is completed.

According to the coal seam condition and the roadway condition, the fluidized drilling gas coal co-mining part is arranged in a lower gateway coal roadway of the coal seam to be mined or in a bottom plate rock roadway of the coal seam to be mined.

Compared with the prior art, when the underground physical fluidization coal mining system and method are adopted for coal mining operation, a stoping face and large mechanical equipment are not required to be arranged, the operation is simple, the safety and reliability are realized, and the safe and efficient mining of difficult-to-mine (left-behind) coal resources such as corner coal, chicken nest coal, geology complex coal seams, thin coal seams, steeply inclined coal seams, left-behind coal pillars and the like can be realized. And secondly, the jet flow breaks up the coal body so that the gas can be fully desorbed and gushed out, the gas extraction amount and extraction concentration of the gas extracted through the gas extraction pipe are higher, the jet flow can be directly used for a gas generator set, and the efficient development and utilization of gas resources can be realized. Moreover, the gas and dust can not be directly discharged into a roadway or a chamber, and an operator is far away from a coal breaking area, so that better operation environment and operation safety can be realized. In addition, after the mining is finished, the coal mining cave can be filled through the filling pipeline, so that the deformation of overlying strata and the subsidence of the earth surface can be reliably controlled, the ecological environment of the earth surface is protected, and the green mining of the coal seam is realized.

Drawings

FIG. 1 is a schematic diagram of the present invention in mining a conventional coal seam, corner coal, or thin seam, wherein arrows indicate arrangement of fluidized borehole gas-coal co-mining portions from a back-to-front perspective;

FIG. 2 is a schematic layout view of the present invention for a filling equipment layout area, a goaf, a coal mining equipment layout area in conventional coal seam, corner coal, thin seam mining;

FIG. 3 is a schematic view of the arrangement of the fluidized borehole gas-coal co-production section from a back-to-front perspective of the present invention;

FIG. 4 is a schematic view of the mounting structure of the high pressure seal drill pipe and orifice sealing unit of the present invention;

FIG. 5 is a schematic diagram of the structure of the water-coal separation unit of the present invention;

FIG. 6 is a schematic diagram of the present invention for mining high gas outburst coal seams, steeply inclined coal seams, and complex geological conditions, wherein arrows indicate the arrangement of the fluidized borehole gas-coal co-mining portions from a back-to-front perspective.

In the figure: 1. a jet coal breaking unit; 1-1, a coal breaking drill bit; 1-2, a spraying device; 1-2-1, a jet nozzle; 1-3, an extension device; 1-3-1, jet nozzle; 1-4, sealing the drill rod at high pressure; 1-5, high-pressure water tail; 1-6, drilling machine; 1-7, a high-pressure water pump; 2. an orifice sealing unit; 2-1, front sealing sleeve; 2-2, sealing the unit body; 2-3, rear sealing sleeve; 2-4, supporting a sealing ring; 2-5, a gas outlet; 2-6, a water coal outlet; 3. a water-coal separation unit; 3-1, a vibrating screen; 3-2, a scraper conveyor; 3-3, a sedimentation tank; 3-3-1, a first-stage sedimentation tank; 3-3-2, a secondary filter tank; 3-4, a filter press; 4. drilling a filling area; 5. drilling and mining a cave; 6. a coal water collection box; 7. a slurry transfer pump; 8. high pressure water jet; 9. a coal mining layer is to be mined; 10. a lower gate; 11. and a gas extraction pipe.

Detailed Description

The invention will be further described with reference to the accompanying drawings (hereinafter described with reference to the direction of drilling of the high pressure seal drill rods 1-4 as the front).

The underground physical fluidization coal mining system comprises a fluidization drilling gas-coal co-mining part, wherein the fluidization drilling gas-coal co-mining part comprises a jet coal breaking unit 1, an orifice sealing unit 2 and a water-coal separating unit 3 as shown in figures 1, 3 and 6;

as shown in fig. 4, the jet coal breaking unit 1 comprises a coal breaking drill bit 1-1, a jet device 1-2, an extension device 1-3, a high-pressure sealing drill rod 1-4, a high-pressure water tail 1-5, a drilling machine 1-6 and a high-pressure water pump 1-7; the high-pressure sealing drill rod 1-4 is of a cylindrical structure with consistent outer diameters and in which a hollow water passing structure is arranged in the high-pressure sealing drill rod 1-4, the foremost end of the high-pressure sealing drill rod 1-4 is in sealed installation connection with the extension device 1-3, and the rearmost end of the high-pressure sealing drill rod 1-4 is in sealed installation connection with the high-pressure water tail 1-5; the front end of the stretching device 1-3 is hermetically provided with a spraying device 1-2, and the front end of the spraying device 1-2 is in threaded connection with a coal breaking drill bit; the high-pressure water output end of the high-pressure water pump 1-7 can be in airtight installation connection with the high-pressure water tail 1-5 through a pipeline; the drilling machine 1-6 is in transmission connection with the high-pressure sealing drill rod 1-4;

the orifice sealing unit 2 comprises a front sealing sleeve 2-1, a sealing unit main body 2-2 and a rear sealing sleeve 2-3 which are coaxially and oppositely and hermetically installed in sequence, a high-pressure sealing drill rod 1-4 can pass through the orifice sealing unit 2 along the front and rear axial direction of the orifice sealing unit 2, a coal water flow passage is formed between the outer surface of the high-pressure sealing drill rod 1-4 and the inner surface of the front sealing sleeve 2-1, a supporting sealing ring 2-4 which is in sealing fit with the outer diameter of the high-pressure sealing drill rod 1-4 and is used for sealing and supporting the high-pressure sealing drill rod 1-4 is coaxially and fixedly arranged in the rear sealing sleeve 2-3, the sealing unit main body 2-2 is of a container structure with a large-volume inner cavity, the top end of the sealing unit main body 2-2 is provided with a gas outlet 2-5 which is communicated with the inner cavity of the sealing unit main body, the gas outlet 2-5 is hermetically communicated with a mine gas pumping pipe 11 through a pipeline, the bottom end of the sealing unit main body 2-2 is provided with a water coal outlet 2-6 which is communicated with the inner cavity of the sealing unit through a pipeline, the water outlet 2-6 is connected with the input end of a coal water collecting box 6 through the pipeline and the coal water collecting box 6, and the output end of the water collecting box 6 is connected with the input end of a slurry pump 7 through the slurry pump 7.

As shown in fig. 5, the water-coal separation unit 3 includes a vibrating screen 3-1, a scraper conveyor 3-2, a sedimentation tank 3-3, and a filter press 3-4; the outlet of a connecting pipeline at the output end of the slurry conveying pump 7 is arranged above the material input end of the vibrating screen 3-1, the material output end of the vibrating screen 3-1 is arranged above the material input end of the scraper conveyor 3-2, the sedimentation tank 3-3 comprises a primary sedimentation tank 3-3-1 and a secondary filtering tank 3-3-2, a vibration dehydration water outlet of the vibrating screen 3-1 is connected with the primary sedimentation tank 3-3-1 through a pipeline, a sludge pump at the material input end of the filter press 3-4 is arranged in the primary sedimentation tank 3-3-1, a filter pressing water outlet of the filter press 3-4 is connected with the secondary filtering tank 3-3-2 through a pipeline, and the input end of the high-pressure water pump 1-7 is connected with the secondary filtering tank 3-3-2 through a pipeline.

In order to ensure the coal water removal efficiency, the high-pressure sealing drill rods 1-4 with multiple front ends can adopt large-diameter triangular drill rods, four-edge drill rods, six-edge drill rods and other large-diameter edge drill rods with multiple edges, or the high-pressure sealing drill rods with edges and corners and the round sealing drill rods are in cross sealing connection.

In order to achieve a better hydraulic coal breaking effect, the jet device 1-2 can be provided with 1-8 jet nozzles 1-2-1, the jet direction of the jet nozzles 1-2-1 and the axial direction of the jet device 1-2 are at 45-90 degrees, the jet nozzles 1-2-1 are uniformly distributed along the circumferential direction of the jet device 1-2, and/or the jet nozzles 1-2-1 are uniformly distributed along the axial direction of the jet device 1-2.

In order to improve the hydraulic coal breaking range, the stretching device 1-3 is provided with a plurality of diameter-expanding swing arms which are symmetrically arranged relative to the center of the base body, the length of the diameter-expanding swing arms can reach 0.5-2.5 m, the diameter-expanding swing arms can radially stretch along the drill rod through a center rotating shaft, drainage channels are arranged in the diameter-expanding swing arms and the base body, and the diameter-expanding swing arms and the base body are matched with the jet nozzle 1-3-1 arranged in front of the swing arms to generate high-pressure water jet.

When the underground physical fluidization coal mining system is used for mining difficult-to-mine (carry-over) coal resources, the underground physical fluidization coal mining system is arranged at the low end position of the inclined trend of the coal seam, and a rollback coal mining mode is adopted. The fluidized drilling gas-coal co-mining part can be arranged in a coal roadway of a lower crossheading 10 of the layer 9 to be mined as shown in fig. 1, or can be arranged in a floor rock roadway of the layer 9 to be mined as shown in fig. 6, and is flexibly arranged according to the conditions of a coal seam and the conditions of the roadway.

When the fluidized drilling gas coal co-mining part of the underground physical fluidized coal mining system is utilized for coal mining operation, the drilling holes penetrating through the coal seam 12 are arranged as upward holes from bottom to top along the inclined trend of the coal seam, so that coal mining operation can be carried out by multiple drilling holes at the same time. Specific:

step one, drilling construction: the coal breaking drill bit 1-1 is arranged at the front end of the high-pressure sealing drill rod 1-4, the high-pressure water tail 1-5 is arranged at the rear end of the high-pressure sealing drill rod 1-4, and the drilling machine 1-6 is utilized to drive the high-pressure sealing drill rod 1-4 to drill upwards for 2-4 m along a coal seam and then stop drilling; withdrawing the high-pressure sealing drill rod 1-4 and the coal breaking drill bit 1-1, replacing the coal breaking drill bit 1-1 with a reaming drill bit, reaming the hole opening of the drilled hole, wherein the reaming inner diameter is larger than the outer diameter of the front sealing sleeve 2-1; the front sealing sleeve 2-1 is put in a reaming position, grouting is carried out in an annulus between a drilling hole and the front sealing sleeve 2-1 to fix the front sealing sleeve 2-1, then the sealing unit main body 2-2 and the rear sealing sleeve 2-3 are coaxially and hermetically and fixedly arranged on the front sealing sleeve 2-1, a gas outlet 2-5 is hermetically and fixedly arranged with a mine gas pumping and draining pipe 11 through a pipeline, and a water-coal outlet 2-6 is connected with the input end of a coal water collecting box 6 through a pipeline; replacing the reaming bit with a coal breaking bit 1-1, enabling the high-pressure sealing drill rod 1-4 and the coal breaking bit 1-1 to pass through the orifice sealing unit 2, driving the high-pressure sealing drill rod 1-4 to continuously drill forward to a set distance by utilizing the drilling machine 1-6, stopping drilling, withdrawing the high-pressure sealing drill rod 1-4 and the coal breaking bit 1-1, and finishing coal mining drilling construction;

step two, fluidized gas coal simultaneous mining: the stretching device 1-3, the spraying device 1-2 and the coal breaking drill bit 1-1 are sequentially arranged at the front end of the high-pressure sealing drill rod, and the high-pressure sealing drill rod 1-4, the stretching device 1-3, the spraying device 1-2 and the coal breaking drill bit 1-1 penetrate through the orifice sealing unit 2 and extend into the hole bottom position of the coal mining drill hole; starting a high-pressure water pump 1-7, controlling a high-pressure sealing drill rod 1-4 to rotate at a proper rotating speed through a drilling machine 1-6 to perform hydraulic coal breaking, enabling broken coal bodies to flow back to the inner cavity of a sealing unit main body 2-2 along with water flowing through an annular space between a drilling hole and the high-pressure sealing drill rod 1-4, enabling the broken coal bodies to flow into a collecting box 6 through a water coal outlet 2-6, and finally enabling gas released by the broken coal bodies to be sent to a water coal separation unit 3 through a slurry conveying pump 7, enabling gas released by the broken coal bodies to flow into the inner cavity of the sealing unit main body 2-2 through the annular space between the drilling hole and the high-pressure sealing drill rod 1-4 and enter a mine gas pumping pipe 11 through a gas outlet 2-5; and a stepping back type coal mining mode is adopted, the high-pressure sealing drill rod 1-4 is controlled to move back and forth within a set range until the coal yield of a drilled hole is greatly reduced, then the high-pressure sealing drill rod 1-4 is controlled to back and set a step distance, and the like, so that the cyclic work of back-coal breaking-back-coal breaking is carried out until the injection device 1-2 approaches the orifice sealing unit 2, and the exploitation of coal bodies around the drilled hole is completed.

Step three, drilling and filling: as shown in fig. 2, a drilling coal mining cavity 5 is formed in the back-off process of the high-pressure sealing drill rod 1-4, after all coal around the drilling hole is extracted, grouting and filling are carried out on the drilling coal mining cavity 5, a drilling filling area 4 is formed after grouting of the whole drilling coal mining cavity 5, after the drilling filling area 4 is formed by grouting, other coal mining holes are arranged at intervals for continuous physical fluidization coal mining, after filling slurry in the drilling coal mining filling area 4 is solidified, coal mining holes are arranged in the adjacent area of the drilling coal filling area 4 for physical fluidization coal mining.

In order to enlarge the coal mining diameter and increase the single drill Kong Caimei, the coal mining process in the single rollback set step is as follows: firstly, setting a high-pressure water pump 1-7 to work in a pressure range of 8-15 MPa, and enabling high-pressure water to flow out completely through a jet nozzle 1-2-1 of a jet device 1-2, and cutting and crushing coal bodies in the step; when the coal output in the working state is greatly reduced, the working pressure of the high-pressure water pump 1-7 is increased to be more than 15MPa, so that high-pressure water flows out completely through the jet nozzle 1-3-1 of the stretching device 1-3, the coal in the step is continuously cut and crushed until the coal output of the drilling hole is greatly reduced again, and the fluidized gas coal simultaneous mining operation in the step is completed.

In order to realize filling of the coal mining cave, the underground physical fluidization coal mining system further comprises a coal mining cave filling part, wherein the coal mining cave filling part comprises a pulping device and a pumping pressure filling device, the pulping device comprises a crusher, a screening machine, a stirrer and a feeder, and the pumping pressure filling device comprises a filling pump and a filling pipeline.

When the underground physical fluidization coal mining system and method are adopted for coal mining operation, a stoping face and large mechanical equipment are not required to be arranged, the operation is simple, safety and reliability are realized, and safe and efficient mining of difficult-to-mine (left-behind) coal resources such as corner coal, honeycomb briquette, geology complex coal seam, thin coal seam, steeply inclined coal seam, left-behind coal pillar and the like can be realized. And secondly, the jet flow breaks up the coal body so that the gas can be fully desorbed and gushed out, the gas extraction amount and extraction concentration of the gas extracted through the gas extraction pipe are higher, the jet flow can be directly used for a gas generator set, and the efficient development and utilization of gas resources can be realized. Moreover, the gas and dust can not be directly discharged into a roadway or a chamber, and an operator is far away from a coal breaking area, so that better operation environment and operation safety can be realized. In addition, after the mining is finished, the coal mining cave can be filled through the filling pipeline, so that the deformation of overlying strata and the subsidence of the earth surface can be controlled, the ecological environment of the earth surface is protected, and the green mining of the coal seam is realized.

Claims (8)

1. The underground physical fluidization coal mining system is characterized by comprising a fluidization drilling gas-coal co-mining part, wherein the fluidization drilling gas-coal co-mining part comprises a jet coal breaking unit (1), an orifice sealing unit (2) and a water-coal separating unit (3);

the jet coal breaking unit (1) comprises a coal breaking drill bit (1-1), a jet device (1-2), an extension device (1-3), a high-pressure sealing drill rod (1-4), a high-pressure water tail (1-5), a drilling machine (1-6) and a high-pressure water pump (1-7); the high-pressure sealing drill rod (1-4) is of a cylindrical structure with consistent outer diameter and a plurality of sections of closed installation connection, and a hollow water passage is arranged in the high-pressure sealing drill rod (1-4); the foremost end of the high-pressure sealing drill rod (1-4) is hermetically provided with a connecting and stretching device (1-3), and the rearmost end of the high-pressure sealing drill rod (1-4) is hermetically provided with a connecting and high-pressure water tail (1-5); the front end of the stretching device (1-3) is hermetically provided with an injection device (1-2), and the front end of the injection device (1-2) is in threaded connection with the coal breaking drill bit (1-1); the high-pressure water output end of the high-pressure water pump (1-7) can be connected with the high-pressure water tail (1-5) in a sealing way through a pipeline; the drilling machine (1-6) is in transmission connection with the high-pressure sealing drill rod (1-4);

the orifice sealing unit (2) comprises a front sealing sleeve (2-1), a sealing unit main body (2-2) and a rear sealing sleeve (2-3) which are coaxially and oppositely and hermetically arranged in sequence; the high-pressure sealing drill rod (1-4) can pass through the orifice sealing unit (2) along the axial direction of the orifice sealing unit (2), and a coal water flow passage is formed between the outer surface of the high-pressure sealing drill rod (1-4) and the inner surface of the front sealing sleeve (2-1); a supporting sealing ring (2-4) which is in sealing fit with the outer diameter of the high-pressure sealing drill rod (1-4) and is used for sealing and supporting the high-pressure sealing drill rod (1-4) is coaxially and fixedly arranged in the rear sealing sleeve (2-3); the sealing unit main body (2-2) is of a container structure with a large-volume inner cavity, the top end of the sealing unit main body (2-2) is provided with a gas outlet (2-5) communicated with the inner cavity of the sealing unit main body, the gas outlet (2-5) is communicated with a mine gas pumping pipe (11) in a sealing way through a pipeline, the bottom end of the sealing unit main body (2-2) is provided with a water-coal outlet (2-6) communicated with the inner cavity of the sealing unit main body, the water-coal outlet (2-6) is connected with the input end of the coal water collecting box (6) through a pipeline, and the output end of the coal water collecting box (6) is connected with the input end of the slurry conveying pump (7) through a pipeline;

the water-coal separation unit (3) comprises a vibrating screen (3-1), a scraper conveyor (3-2), a sedimentation tank (3-3) and a filter press (3-4); an outlet of an output end connecting pipeline of the slurry conveying pump (7) is arranged above a material input end of the vibrating screen (3-1), and a material output end of the vibrating screen (3-1) is arranged above a material input end of the scraper conveyor (3-2); the sedimentation tank (3-3) comprises a primary sedimentation tank (3-3-1) and a secondary filtering tank (3-3-2), a vibration dehydration outlet of the vibrating screen (3-1) is connected with the primary sedimentation tank (3-3-1) through a pipeline, a sludge pump at the material input end of the filter press (3-4) is arranged in the primary sedimentation tank (3-3-1), a filter pressing outlet of the filter press (3-4) is connected with the secondary filtering tank (3-3-2) through a pipeline, and the input end of the high-pressure water pump (1-7) is connected with the secondary filtering tank (3-3-2) through a pipeline.

2. A downhole physical fluidization coal mining system according to claim 1, further comprising a coal mining cavity filling portion including a pulping apparatus including a crusher, a screening machine, a stirrer, and a batching machine, and a pumping and filling apparatus including a filling pump and a filling pipe.

3. A downhole physical fluidization coal mining system according to claim 1 or 2, wherein the jet device (1-2) is provided with 1-8 jet nozzles (1-2-1), the jet direction of the jet nozzles (1-2-1) and the axial direction of the jet device (1-2) are at 45-90 degrees, the jet nozzles (1-2-1) are uniformly distributed along the circumferential direction of the jet device (1-2), and/or the jet nozzles (1-2-1) are uniformly distributed along the axial direction of the jet device (1-2).

4. A downhole physical fluidization coal mining system according to claim 3, wherein the stretching device (1-3) is provided with a plurality of diameter-enlarging swing arms symmetrically arranged relative to the center of the base body, the length of the diameter-enlarging swing arms is 0.5-2.5 m, the diameter-enlarging swing arms can radially stretch along the drill rod through the center rotating shaft, drainage channels are arranged in the diameter-enlarging swing arms and the base body, and the drainage channels are matched with jet nozzles (1-3-1) arranged in front of the swing arms to generate high-pressure water jet.

5. A downhole physical fluidized coal mining system according to claim 1 or 2, wherein the support seal rings (2-4) are arranged in at least two groups in the axial direction of the rear seal sleeve (2-3).

6. A method of downhole physical fluidisation coal mining based on a downhole physical fluidisation coal mining system as claimed in claim 1, comprising the steps of:

step one, drilling construction: the coal breaking drill head (1-1) is arranged at the front end of the high-pressure sealing drill rod (1-4), the high-pressure water tail (1-5) is arranged at the rear end of the high-pressure sealing drill rod (1-4), and the drill (1-6) is utilized to drive the high-pressure sealing drill rod (1-4) to drill upwards for 2-4 m along a coal seam and then stop drilling; withdrawing the high-pressure sealing drill rod (1-4) and the coal breaking drill bit (1-1), replacing the coal breaking drill bit (1-1) with a reaming drill bit, reaming the drilled hole, wherein the reaming inner diameter is larger than the outer diameter of the front sealing sleeve (2-1); the method comprises the steps of putting a front sealing sleeve (2-1) into a drilled hole after reaming, grouting in an annulus between the drilled hole and the front sealing sleeve (2-1) to fix the front sealing sleeve (2-1), coaxially and hermetically mounting a sealing unit main body (2-2) and a rear sealing sleeve (2-3) on the front sealing sleeve (2-1), hermetically and fixedly mounting a gas outlet (2-5) with a mine gas pumping pipe (11) through a pipeline, and connecting a water coal outlet (2-6) with the input end of a coal water collecting box (6) through a pipeline; replacing the reaming bit with a coal breaking bit (1-1), driving the high-pressure sealing drill rod (1-4) to continuously drill forward to a set distance by using a drilling machine (1-6) after the high-pressure sealing drill rod (1-4) and the coal breaking bit (1-1) pass through an orifice sealing unit (2), stopping drilling after the high-pressure sealing drill rod (1-4) and the coal breaking bit (1-1) are withdrawn, and finishing coal mining drilling construction;

step two, fluidized gas coal simultaneous mining: the stretching device (1-3), the spraying device (1-2) and the coal breaking drill bit (1-1) are sequentially arranged at the front end of the high-pressure sealing drill rod (1-4), and the high-pressure sealing drill rod (1-4), the stretching device (1-3), the spraying device (1-2) and the coal breaking drill bit (1-1) penetrate through the orifice sealing unit (2) and extend into the hole bottom position of the coal mining drill hole; after the high-pressure water pump (1-7) is started, the high-pressure sealing drill rod (1-4) is controlled by the drilling machine (1-6) to rotate at a proper rotating speed to hydraulically break coal, broken coal flows back to the inner cavity of the sealing unit main body (2-2) along with water flowing through an annulus between the drilling hole and the high-pressure sealing drill rod (1-4), flows into the collecting box (6) through the water-coal outlet (2-6), and is finally sent to the water-coal separation unit (3) by the slurry conveying pump (7); the gas released by the broken coal body is flushed into the inner cavity of the sealing unit main body (2-2) through the annular space between the drill hole and the high-pressure sealing drill rod (1-4) and enters the mine gas pumping pipe (11) through the gas outlet (2-5); adopting a stepping backward coal mining mode, controlling the high-pressure sealing drill rod (1-4) to move back and forth within a set range until the coal yield of a drilled hole is greatly reduced, then controlling the high-pressure sealing drill rod (1-4) to move backward for a set step distance, and then performing 'backward-coal breaking-backward-coal breaking' cyclic work by analogy until the stretching device (1-3), the spraying device (1-2) and the coal breaking drill bit (1-1) are close to the orifice sealing unit (2), so as to finish the exploitation of coal bodies around the drilled hole;

step three, drilling and filling: and forming a drilling coal mining cave (5) in the retreating process of the high-pressure sealing drill rod (1-4), grouting and filling the drilling coal mining cave (5) after all coals around the drilling holes are mined, forming a drilling filling area (4) after grouting the whole drilling coal mining cave (5), continuously carrying out physical fluidization coal mining on other coal mining holes at intervals set at a set distance after grouting to form the drilling filling area (4), and carrying out physical fluidization coal mining on the coal mining holes in the vicinity of the drilling filling area (4) after filling slurry in the drilling filling area (4) is solidified.

7. A method of downhole physical fluidization coal mining according to claim 6, wherein the coal mining process in each set back-off step is: firstly, a high-pressure water pump (1-7) is arranged to work within the pressure range of 8-15 MPa, so that high-pressure water flows out completely through a jet nozzle (1-2-1) of a jet device (1-2), and coal bodies in the step are cut and crushed; when the coal output in the working state is greatly reduced, the working pressure of the high-pressure water pump (1-7) is increased to be more than 15MPa, so that the high-pressure water flows out completely through the jet nozzle (1-3-1) of the stretching device (1-3), the coal in the step is continuously cut and crushed until the coal output of the drilling hole is greatly reduced again, and the fluidized gas coal simultaneous mining operation in the step is completed.

8. A downhole physical fluidization coal mining method according to claim 6, wherein the fluidization drilling gas-coal co-mining portion is arranged in a coal roadway of a lower gate (10) of the layer (9) to be mined or in a floor rock roadway of the layer (9) to be mined according to the conditions of the coal seam and the roadway.

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