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128results about How to "Increase extraction concentration" patented technology

Gas extraction and drilling cooperative drilling and protecting integrated system for soft coal seams and process

ActiveCN102587828AOvercome the problem of frictional resistanceReduce displacementDrilling rodsGas removalHydraulic pumpAir compressor
A gas extraction and drilling cooperative drilling and protecting integrated system for soft coal seams and process belong to soft coal seam cooperative drilling and protecting systems and process. The gas extraction and drilling cooperative drilling and protecting integrated system mainly consists of a control table, a hydraulic pump station, an air compressor, a feeding device, a drill stem, a hole protecting tube, a drill bit and the like. The hole protecting tube is located in the drill stem, and the hole protecting tube and the drill stem are synchronously connected and drill cooperatively. The depth of a drilled hole is equal to the length of the hole protecting tube. Finally, the hole protecting tube penetrates through the drill bit, and the drill stem is withdrawn while the hole protecting tube is remained in the hole to realize functions of supporting a hole wall and extracting gas. The system and the process are convenient in operation, the hole protecting tube and the drill stem realize cooperative drilling and protecting, the hole protecting tube is easy to be remained in the drilled hole, problems that the hole collapses and the hole protecting tube is difficult to be fed to the drilled hole can be resolved, the hole protecting depth is high, the hole wall can be supported more effectively, deformation and collapse are prevented, accordingly high gas extraction concentration and flow of the soft coal seams are guaranteed, and the gas extraction and drilling cooperative drilling and protecting integrated system for soft coal seams and the process are particularly applicable to quite soft coal seams with the value of the firmness factor f smaller than 0,3.
Owner:CHINA UNIV OF MINING & TECH

Method for extracting coal bed gas from circulating pulse type low temperature freeze-thawed anti-reflection coal

ActiveCN106337672AImprove anti-reflection efficiencyImprove gasification expansion efficiencyFluid removalGas removalFreeze thawingUltrasound attenuation
The invention discloses a method for extracting coal bed gas from circulating pulse type low temperature freeze-thawed anti-reflection coal. Firstly, a borehole and multiple rows of guiding slots are constructed in a coal bed, the guiding slots are communicated with the borehole and extend to two sides of the borehole in the direction perpendicular to the borehole in the coal bed, and coal bed gas extraction boreholes are formed at the outer ends of the guiding slots. A liquid low-temperature medium is injected into the borehole and the guiding slots in a high-pressure pulse mode, the coal bed is freeze-thawed by adopting a pulse circulating low temperature freeze-thawing method to fracture for increasing reflection, and a coal bed gas extraction fracture network is thus formed. Coal bed gas is extracted via the coal bed gas extraction boreholes. By combining freeze-thawing erosion with coal bed gas extraction and combining pulse circulating injection of the liquid low-temperature medium with freeze-thawing phase change fracture, the method significantly improves the anti-reflection efficiency of coal. The method is simple, feasible and low in construction cost, can effectively improve the single-pore extraction quantity and extraction concentration of coal bed gas and prolong the attenuation time of gas concentration, and is particularly suitable for coal bed gas extraction in low-osmosis and high-gas bearing coal beds.
Owner:CHINA UNIV OF MINING & TECH

Powder particle-high-pressure grouting crack packing gas extraction drilling and sealing device and method

ActiveCN109577908AImprove radial stabilityEasy to storeFluid removalGas removalPack materialEngineering
The invention provides a powder particle-high-pressure grouting crack packing gas extraction drilling and sealing device and method. The powder particle-high-pressure grouting crack packing gas extraction drilling and sealing device and method is applicable to underground coal mines. The powder particle-high-pressure grouting crack packing gas extraction drilling and sealing device comprises an outer bag and an inner bag, wherein the rear of the outer bag is provided with a fixing unit on a gas extraction pipe; the inner bag is provided with a screen pipe, a bag grouting pipe and a grouting pipe which penetrate through the fixing unit, the tail portions of the screen pipe, the bag grouting pipe and the grouting pipe are arranged at the rear of the outer bag, and the tail ends of the screenpipe, the bag grouting pipe and the grouting pipe are provided with valves; quick lime powder coerced by carbon dioxide is guided into the space among packing materials via the screen pipe to block fractures around a drilled hole through reaction products; cement mortar is filled in by the grouting pipe to achieve the aim of packing cracks and actively supporting the drilled hole. Therefore, thepowder particle-high-pressure grouting crack packing gas extraction drilling and sealing device can effectively reduce the influence of mining damage, prolong the effectively extraction period of drilling gas extraction, increase the concentration of extracted gas, maintain stability of the drilled hole, significantly improve the coal seam gas extracting effects and ensure safety of underground workers.
Owner:CHINA UNIV OF MINING & TECH

Mining-coal bed nearly horizontal gas extraction borehole sealing method

A mining-coal bed nearly horizontal gas extraction borehole sealing method is mainly suitable for gas extraction boreholes at sites like coal faces in underground coal mines and coal roadways. The sealing method mainly includes two parts: static sealing and dynamic sealing. For a gas extraction borehole, static sealing is performed firstly and includes two times of grouting: for the first grouting, expansion cement grout is adopted to seal positions outside a fissure zone, and for the second grouting, slurry is adopted to seal positions inside the fissure zone; after a period of time, dynamic sealing is performed and includes that the expansion cement grout and the slurry are constantly grouted into the borehole by utilizing underground compressed air to enable the borehole and surrounding fractures to be always filled with the expansion cement grout and the slurry so as to realize dynamic sealing. By the method, grouting fluid can be enabled to effectively seal space inside the borehole and coal fracture areas surrounding the borehole in real time, and maximization of space and fracture sealing is realized. The mining-coal bed nearly horizontal gas extraction borehole sealing method is simple in structure, convenient to operate, low in cost and evident in effect.
Owner:SHANXI LUAN ENVIRONMENTAL ENERGY DEV +1

Coal and gas co-mining method based on mining fissure elliptic paraboloid zone

The invention relates to a coal and gas co-mining method based on a mining fissure elliptic paraboloid zone; the spatial-temporal evolution and the distribution characteristics of the fissure elliptic paraboloid zone which is formed by coating a rock stratum when a working face is propelled during coal bed mining are analyzed through a physically similar material simulation experiment and numerical simulation calculation, the height h1 of an inner elliptic paraboloid surface, the height h2 of an outer elliptic paraboloid surface, incisions and relevant parameters of the working face, an intake airway and a return airway are obtained, and the mathematical formula of the elliptic paraboloid zone is deduced. The results of the physically similar material simulation experiment and a numerical simulation experiment are input into the mathematical formula of the elliptic paraboloid zone, so that the destination of a gas extraction drilled hole and the height of a gas extraction roadway can be determined conveniently. Spot effect inspection proves that putting the destination of the gas extraction drilled hole and a gas extraction roadway into the fissure elliptic paraboloid zone can greatly improve the extraction concentration of gas, so that the coal mining on the working face and continuous extraction of pressure-relieved gas can be promoted synchronously, and a coal and gas co-mining mechanism in high-gas coal bed mining is worked out.
Owner:XIAN UNIV OF SCI & TECH

Coal mine gas extraction system and method for increasing concentration of gas extraction by reducing and pore broadening

The invention discloses a coal mine gas extraction system and method for increasing the concentration of gas extraction by reducing and pore broadening. The coal mine gas extraction system comprises acoal mine drilling machine, a drill hole drill bit, a hole sealing mechanism, a grouting piping system, a gas extraction piping system and a reamer bit. The reamer bit comprises a power transmissionmechanism and three bit fins. The power transmission mechanism comprises a sun gear and three planetary gears, the sun gear is fixedly connected to a sun gear rotating shaft, the planetary gears are rotatably connected to a planetary gear rotating shaft, the three bit fins are separately and fixedly connected to the three planetary gears, and the bit fins are connected with cutting teeth through tooth bases. A hydraulic cylinder and an ejection rod are arranged in the sun gear rotating shaft, a spiral sliding groove is formed in the ejection rod, and a sliding block is arranged on the inner wall of the sun gear rotating shaft. The method comprises the steps that 1, hole drilling is performed; 2, pore broadening is performed; 3, hole flushing is performed; 4, grouting and hole sealing are performed; and 5, gas extraction is performed. The coal mine gas extraction system and method for increasing the concentration of gas extraction by reducing and pore broadening has novel and reasonabledesign, high strength of a reamer bit and simple reaming process, can improve hole sealing quality and the concentration of gas extraction, and is practical and effective and easy to popularize.
Owner:XIAN UNIV OF SCI & TECH

Formula of honey refined gum for treating chloasma and preparation method thereof

The invention discloses a formula of a honey refined gum for treating chloasma and a preparation method thereof. The medicinal composition comprises the following crude medicaments in part by weight: 50 to 60 parts of sealwort, 30 to 40 parts of Chinese wolfberry, 10 to 20 parts of donkey-hide gelatin, 5 to 8 parts of cinnamon, 10 to 15 parts of peach blossom, 10 to 15 parts of flower of puncturevine caltrop, 10 to 15 parts of Anhui chrysanthemum flower, 10 to 15 parts of honey suckle, 10 to 15 parts of rose, 10 to 15 parts of dandelion, 10 to 15 parts of gardenia, 20 to 25 parts of mulberry, 15 to 20 parts of dahurian angelica root, 15 to 20 parts of white almond, 20 to 30 parts of white poria, 20 to 30 parts of Chinese yam rhizome, 20 to 30 parts of lily, 10 to 15 parts of dried tangerine peel, 15 to 20 parts of papaya, 15 to 20 parts of citron peel, 10 to 15 parts of folium mori, 15 to 20 parts of peach kernel, 15 to 20 parts of bunge cherry seed and 15 to 20 parts of spina date seed. The honey refined gum has the characteristics of conditioning Yin and Yang, benefiting the spleen and kidney, soothing the liver and regulating Qi, clearing heat and releasing toxin, and invigorating the circulation of blood and relaxing the bowels, can effectively regulate the female endocrine, and has good treatment effect on the chloasma, blackish facial patch, baldness, white hair, insomnia, anxiety and constipation.
Owner:合肥臻和堂健康科技股份有限公司

Gas extracting drilling solid-liquid two-phase hole sealing device and technology

The invention discloses a gas extracting drilling solid-liquid two-phase hole sealing device. The gas extracting drilling solid-liquid two-phase hole sealing device comprises a first capsule bag, a second capsule bag, a third capsule bag, a primary grouting pipe and a secondary grouting pipe, a first hole sealing section is arranged between the first capsule bag and the second capsule bag, and a second hole sealing section is arranged between the second capsule bag and the third capsule bag; and an explosive valve located in the first hole sealing section is formed in the primary grouting pipe, the other end of the secondary grouting pipe is located in the second hole sealing section, and is in communication with the second hole sealing section through a second one-way valve. The inventiondiscloses a gas extracting drilling solid-liquid two-phase hole sealing technology at the same time, a network is connected to perform extracting after the first hole sealing section is subjected tosolid-phase hole sealing, periodic detection of gas extracting concentration is carried out to an extracting drilling hole of which the solid-phase extracting is completed, liquid-phase sealing of thesecond hole sealing section is perform on an extracting drilling hole with gas leakage, and then extracting can be continued. According to the gas extracting drilling solid-liquid two-phase hole sealing device and technology, liquid-phase hole sealing operation can be carried out to an extracting drilling hole with poor hole sealing and the gas leakage, periodic maintenance can be carried out tothe liquid sealing effect, and extracting drilling hole is prevented from densified cumbersome construction.
Owner:HENAN POLYTECHNIC UNIV

Method for injecting high-temperature nitrogen gas for improving coal body permeability after liquid nitrogen gasification circulation

The invention discloses a method for injecting high-temperature nitrogen gas for improving coal body permeability after liquid nitrogen gasification circulation. A gas extraction drill hole is constructed inside a working face roadway; magnetic water is injected into the gas extraction drill hole through a magnetic water injection pipe, and then the magnetic water permeates into a coal body around the gas extraction drill hole; the gas extraction drill hole is filled with liquid nitrogen inside a liquid nitrogen tank; the liquid nitrogen is frozen to permeate into the magnetic water inside the coal body and gasified into nitrogen gas, and the pressure inside the gas extraction hole is increased; the gasified nitrogen gas inside the gas extraction drill hole enters a nitrogen gas heating tank to be collected; the step of freeze thawing is repeatedly executed, and repeated liquid nitrogen gasification circulation is implemented on the gas extraction drill hole; the nitrogen gas collected inside the nitrogen gas heating tank is heated, high temperature nitrogen gas is injected into the gas extraction drill hole, and the coal body is subjected to fracturing through the high temperature nitrogen gas. The coal body is made to generate a weakening region, and then the coal body is subjected to fracturing and permeability improvement, so that the heat storage time of nitrogen gas is shortened, and meanwhile the coal body permeability improvement range is enlarged.
Owner:XUZHOU UNIV OF TECH

Construction method of blood free DNA (deoxyribonucleic acid) library based on Ion ProtonTM sequencing platform, reagents and application of reagents

The invention discloses an Ion Proton-based TM Blood cell-free DNA library construction method, reagents and applications of the sequencing platform, the construction process includes blood cell-free DNA extraction, end repair, fragment selection, adapter ligation, magnetic bead purification, library amplification, library detection, high-throughput sequencing and other steps . The present invention also provides a kind of for constructing based on Ion Proton TM Blood cell-free DNA extraction reagents, end repair reagents, linker ligation reaction reagents, and amplification reagents for the blood cell-free DNA library of the sequencing platform. The invention significantly improves the extraction concentration of fetal free DNA in pregnant women's plasma, and has simple steps and low cost, and improves the success rate of library construction; the optimized library construction system is more convenient for operation and saves costs, and after replacing the magnetic beads, it can be purified and recovered Higher efficiency; library amplification does not require sufficient sample size and secondary detection, and the operation is simpler. The method of the invention is more suitable for non-invasive prenatal diagnosis of fetal chromosomal aneuploidy.
Owner:浙江圣庭生物科技有限公司

Underground dark mining drilling well gas extraction method

The invention discloses an underground dark mining drilling well gas extraction method, comprising the following steps: firstly constructing a gas extraction lane in a hard rock layer below an upper-group coal seam worked out area or above an unmined coal seam of the vertical distance of a firstly mined coal seam; carrying out middle construction on the gas extraction lane along the pushing direction of the firstly mined working face; starting the construction from a dark mining well of an open-off cut side and the part of the open-off cut in the gas extraction lane after construction; constructing the dark mining well the bottom of which is vertical to the top plate of the firstly mined working face at intervals; arranging an extraction pipe connected with the gas extraction pipeline; and connecting the extraction pipelines in the dark mining well into a mine gas extraction system through the gas extraction pipeline for gas predraining before mining, gas extraction in mining and gas extraction after mining. The method has the advantages of a ground drilling well extraction coal seam group, namely large extraction amount, high extraction concentration and good extraction effect, is good in stability and small in work amount, has low possibility to break and is easy to drain.
Owner:CHINA UNIV OF MINING & TECH

Device and method for active hole drilling and sealing

ActiveCN103470212ASolve the existence of a large number of poresSolve the problem of cracksSealing/packingPistonMaterials science
The invention discloses a device and a method for active hole drilling and sealing. The device comprises a gas extraction pipe, a grout injection pipe, a grout return pipe, an inner-block grout disk, an outer-block grout disk, a sealing piston, a gravity hammer and a grout storage tank, wherein the bottom of the grout storage tank is provided with a grout injection opening which is controlled by a grout injection valve and a grout supplementing opening which is controlled by a grout supplementing valve. An inorganic flexible paste body is injected into a drilling space between the inner-block grout disk and the outer-block grout disk through the grout injection pipe, the grout return pipe is connected with the grout storage tank when the grout return pipe is subjected to grout return, the grout injection valve can be opened, the inorganic flexible paste body can be squeezed out by applying sustained pressure to the inorganic flexible paste body in the grout storage tank by the gravity hammer, cracks added around a drilling hole can be sealed and blocked, and the active hole drilling and sealing of the drilling hole can be realized. The device and the method, which are disclosed by the invention, have the advantages that the structure is simple, the operation is convenient, the cost is low, and the using effect is good.
Owner:CHINA UNIV OF MINING & TECH

Gas extraction method based on mining-induced fracture circular rectangular half-space zone

The invention relates to a gas extraction method based on a mining-induced fracture circular rectangular half-space zone. By analyzing dynamic evolution characteristics, a mechanical mechanism and influence factors of the mining-induced fracture zone, the open-off cut side bandwidth is obtained and is about a first weighting interval, the working face side bandwidth changes within 2-3 times of a periodic weighting interval, the bandwidth near a wind inlet lane and the bandwidth near a wind return lane are about the 0.7-0.8 time of the first weighting interval, the height of an inner half-space face and the height of an outer half-space face are controlled by a key stratum position and the deformation, fracture and instability states of a formed masonry beam structure, accordingly, arrangement parameters of end points of mining-induced pressure relief gas extraction drill holes are determined, the field effect test shows that as the gas extraction drill holes are formed in the mining-induced fracture circular rectangular half-space zone, the gas extraction concentration is improved greatly, synchronized advancement of coal mining on a working face and continuous pressure relief gas extraction is achieved, the mechanism of mining coal and gas together at a high-gas coal seam is obtained, and the gas extraction method based on the mining-induced fracture circular rectangular half-space zone is formed.
Owner:XIAN UNIV OF SCI & TECH

System and process for coal seam permeability improvement by inducing hole drilling extraction later-period gas burning explosion

The invention relates to a system and process for coal seam permeability improvement by inducing hole drilling extraction later-period gas burning explosion. The left end of a connecting pipe (2) is connected with a first gas extraction pipe (1); the right end of the connecting pipe is connected with a sealed gas extraction drilling hole (17); a third electromagnetic valve (8) is arranged on a water conveying pipe (10); a water discharging pipe (13) is arranged on a pipeline for connecting the third electromagnetic valve and the connecting pipe; a fourth electromagnetic valve (9) is arranged on the water discharging pipe; a first electromagnetic valve, a second electromagnetic valve, the third electromagnetic valve, the fourth electromagnetic valve, a temperature sensor, a methane sensor and a carbon monoxide sensor are connected with an intelligent controller (12) through connecting wires (11); and an electric spark igniter (14) is connected with an external power supply switch through a conducting wire. The system has the advantages that the operation is simple; the real-time monitoring can be realized; the manual coal seam burning explosion permeability improvement induction is realized; the gas permeability of a coal seam can be improved in a short time; and the problems of high-gas low-permeability coal seam gas extraction difficulty and fast extraction concentration reduction are solved.
Owner:CHINA UNIV OF MINING & TECH +1

Hole drilling and sealing device and method with continuous belt pressure

The invention discloses a hole drilling and sealing device and method with continuous belt pressure. The device comprises a gas extraction pipe, a grouting pipe, a grout return pipe, grout blocking plates, a grout storing tank, a grout pressing plate and a spring, wherein the grout blocking plates are connected to the gas extraction pipe at equal intervals of 10m to enable the gas extraction pipe to be fed into a dill hole, and the outer grout blocking plate is made to be in the drill hole and in the position away from the opening of the drill hole for 1m. Inorganic flexible pasty fluid is injected to the drill hole space between every two grout blocking plates through the grouting pipe; when the grout return pipe performs grout returning, the grout return pipe and a grout supplementing valve on the lower portion of the grout storing tank are connected, an air receiving valve is opened, and continuous air pressure is applied to the inorganic flexible pasty fluid in the grout storing tank; when fractures around the drill hole increase, the inorganic flexible pasty fluid is continuously pressed into the fractures around the drill hole by the air pressure in the well. When the inorganic flexible pasty fluid in the grout storing tank is totally pressed into the drill hole, a pressure relief valve is opened, and a grout pressing plate ascends under the action of the spring. Due to the fact that the inorganic flexible pasty fluid is injected into the grout storing tank again through a grouting valve, the drill hole is effectively sealed through the continuous belt pressure.
Owner:CHINA UNIV OF MINING & TECH

Drill hole inside secondary grouting leaking stoppage device

PendingCN111322107AIncrease gas extraction concentration and scalar volumeIncrease gas extraction concentrationGas removalSealing/packingDrill holeGeotechnical engineering
The invention discloses a drill hole inside secondary grouting leaking stoppage device. The drill hole inside secondary grouting leaking stoppage device comprises an injection pipe composed of a plurality of single-section pipes which are connected in sequence, all the single-section pipes comprise gas injection pipes and grouting pipes, the grouting pipes are arranged inside the gas injection pipes in a sleeved manner, wherein the grouting pipes are connected with the grouting pipes, the gas injection pipes are connected with the gas injection pipes, the inner ends of the multiple mutually-connected gas injection pipes stretch out of the inner end of a gas extraction pipe, get over a fracture zone of a drill hole and are connected with and communicate with an inner end gasbag, the parts,located at the inner end of the gas extraction pipe, of the multiple mutually-connected gas injection pipes are connected with and communicate with an outer end gasbag, the gas extraction pipe and oneend of an inlet of the drill hole are further provided with a sealing body, the ends, located at the drill hole inlet, of the multiple gas injection pipes of the injection pipe are connected with gassupply equipment, and the ends, located at the drill hole inlet, of the multiple grouting pipes of the injection pipe are connected with grouting equipment. By means of the drill hole inside secondary grouting leaking stoppage device, precision grouting with pressure can be performed on the failure drill hole fracture development position, so that the gas extraction failure drill hole extractionfunction is activated and restored, and the gas extraction concentration and purity are increased.
Owner:YUWU COAL CO LTD OF SHANXI LUAN GRP +1

Gas extraction downward hole sealing device and hole sealing method adopting same

InactiveCN108625820AAvoid the influence of extraction effectSmall footprintFluid removalGas removalSlurryEngineering
The invention discloses a gas extraction downward hole sealing device and further discloses a hole sealing method based on the gas extraction downward hole sealing device. The gas extraction downwardhole sealing device comprises a two-way bundle tube, wherein the two ways of bundle tube bodies serve as an extraction tube and a drainage tube correspondingly. The two-way bundle tube is put downwards to a coal seam floor at the hole bottom, and holes are formed in the part, put downwards to the area between coal seam floor and the hole bottom section, of the two-way bundle tube; the two-way bundle tube is sleeved with a hole-sealing pocket, the hole-sealing pocket is arranged at the in-hole base bottom and used for sealing a drilled hole; and a slurry-injection tube is further arranged on the hole-sealing pocket, inserted into the hole-sealing pocket along the drilled hole and used for injecting slurry into the hole-sealing pocket and the drilled hole. The gas extraction downward hole sealing device has the advantages that the influence of joint air leakage on the extraction effect is avoided, the occupied space of a sleeve in the hole is reduced, the hole-sealing quality is improved, and the extraction concentration is increased by six times or above; and hole-sealing materials are simple, and the single hole cost is relatively saved by 50%.
Owner:HUAINAN MINING IND GRP

Bedding drill hole air-leakage-preventing gas extraction method

ActiveCN108104865AReduce air leakageIncrease gas extraction concentrationGas removalSealing/packingCoalDrill hole
Disclosed is a bedding drill hole air-leakage-preventing gas extraction method. The bedding drill hole air-leakage-preventing gas extraction method comprises two stages of building of a main gas extraction system and building of an auxiliary gas extraction system, specifically, firstly, a main gas extraction pipeline is laid inside a roadway, bedding extraction drill holes are constructed, the bedding extraction drill holes are sealed, and drill hole gas extraction pipes are connected to the main gas extraction pipeline to conduct gas extraction; and after the drill holes in the roadway are all sealed to conduct extraction, an airtight wall is constructed at an opening of the roadway where the drill holes are constructed, an auxiliary gas extraction pipeline is laid, and an auxiliary extraction pipe is connected with an auxiliary gas pump extraction pipeline to conduct auxiliary extraction. According to the bedding drill hole air-leakage-preventing gas extraction method, under the effect of the auxiliary extraction negative pressure, the atmospheric pressure in the roadway can be gradually reduced and finally reaches or approximates to the extraction negative pressure in the drillholes, and the problem that air leakage is serious in the bedding drill hole extraction process can be effectively solved; the technology is simple, implementation is easy, and a large amount of laborcost can be saved; and the bedding drill hole air-leakage-preventing gas extraction method is suitable for bedding drill hole gas extraction of various coal mines, and particularly suitable for mineswhere air leakage is serious in the extraction process.
Owner:CHINA UNIV OF MINING & TECH

Coal bed methane extraction method based on directional drilling and liquid nitrogen freezing heat cracking

The invention relates to a coal bed methane extraction method based on directional drilling and liquid nitrogen freezing heat cracking, and belongs to the technical field of methane treatment. An inclined drill hole is formed in the upper roadway of the extraction work face, and the inclined drilled hole is merged into an extraction pipe network to be subjected to methane extraction; after the work face methane extraction amount is attenuated, the inclined drill hole is detected, a drill hole with extraction failure is marked, meanwhile, a long-distance orientation drill hole is constructed ina retracement channel or air return main roadway of the extraction work face in the coal seam direction to serve as a liquid nitrogen injection hole, liquid nitrogen is injected into the long-distance orientation drill hole, through detection of the temperature in the drill hole marked as extraction failure, whether the drill hole is a liquid nitrogen influence hole or not is judged, if the holeis the liquid nitrogen influence hole, high-temperature air is injected into the drill hole, and the coal around the drill hole is cracked under the freezing heat condition, and the coal permeation characteristics are improved. The methane extraction amount is improved, the process is simple, and the work cost is low.
Owner:CHINA COAL TECH & ENG GRP CHONGQING RES INST CO LTD
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