A room and pillar goaf fire extinguishing method and device

Abstract

A room-and-pillar goaf fire extinguishing method and device, including a sand-flushing and filling fire extinguishing device. The sand-flushing and filling fire extinguishing device includes a welded pipe at the inlet end. One end of the welded pipe at the inlet end is connected to a tee through eccentric diameter change and diameter change. The other end of the tee is connected to the welded pipe at the outlet end through diameter change and eccentric diameter change. The third port of the tee is connected to a diameter changer. The other end of the welded pipe at the outlet end is connected to an elbow and extends into a drill hole. A plug plate is installed at the place where the welded pipe extends into the drill hole. A threaded pipe joint and a two-piece ball valve are arranged on the plug plate. A flange is arranged on the plug plate. The other end of the welded pipe at the inlet end is connected to a water pump. This device and method can bring a fire extinguishing process with good fire extinguishing effect, fast fire extinguishing speed and low cost to the current room-and-pillar goaf fire, achieving the purpose of efficiently and quickly extinguishing the room-and-pillar goaf fire on the premise of ensuring economy.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal mine fire prevention and extinguishing, and particularly relates to a method and device for extinguishing fire in a room and pillar goaf. Background Art

[0002] Nowadays, there are a large number of room and pillar goafs above the large-scale mechanized mining areas, resulting in the following main problems in daily mining:

[0003] (1) A large number of room and pillar coal pillars are prone to form local stress concentration. When the stress concentration is too large, over time, due to natural weathering, creep, rupture, heat accumulation, etc. inside the coal pillars, in the case of appropriate air leakage, they are extremely easy to be oxidized and cause coal spontaneous combustion accidents. When mining operations are carried out, the mining influence causes the fissures to develop and communicate with adjacent goafs, and multi-region continuous air leakage will occur under the influence of wind pressure. When the accumulated floating coal in the overlying goaf is in the air leakage and oxygen supply area, it will lead to the occurrence of coal spontaneous combustion accidents;

[0004] (2) The leakage of toxic and harmful gases caused by the spontaneous combustion of the overlying goaf poses a serious threat and hidden danger to the life safety of underground workers;

[0005] (3) The large-area collapse of the roof in the room and pillar goaf will cause instantaneous instability and roof weighting, and the resulting hurricanes and rock burst disasters will pose a serious threat and hidden danger to the life safety of underground workers and the property safety of mine mining equipment and facilities.

[0006] The current main solutions at home and abroad still stay at the fire extinguishing technology level of the overlying goaf, and deal with it in time when abnormalities are found. The main prevention and control measures include ground drilling for water injection, grouting, and injecting colloids, etc. Their disadvantages are obvious, as follows:

[0007] (1) The effect of drilling for water injection is poor, the coverage area is small, the fire source point cannot be dealt with, and it is easy to cause water inrush in the lower goaf;

[0008] (2) Ground drilling for grouting is applicable to floor fires. For roof and roadway side fires at high positions, the treatment time is slow and the difficulty is great;

[0009] Ground injection of colloids has a good fire extinguishing effect, but the cost is high. For the treatment of large-scale fire areas, the economic effect is not ideal. Summary of the Invention

[0010] In order to overcome the above technical problems, the purpose of the present invention is to provide a method and device for extinguishing fire in a room and pillar goaf. The device and method can bring a fire extinguishing process with good fire extinguishing effect, fast fire extinguishing speed and low cost to the current fire in the room and pillar goaf, and achieve the purpose of efficiently and quickly extinguishing the fire in the room and pillar goaf on the premise of ensuring economy.

[0011] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0012] A room-and-pillar goaf fire extinguishing device includes a sand-flushing and grouting fire extinguishing device. The sand-flushing and grouting fire extinguishing device includes a welded pipe 1 at the inlet end. One end of the welded pipe 1 at the inlet end is connected to a tee 8 through an eccentric reducer 4 and a reducer 5. The other end of the tee 8 is connected to the welded pipe 1 at the outlet end through the reducer 5 and the eccentric reducer 4. The third port of the tee 8 is connected to a reducer 6. The other end of the welded pipe 1 at the outlet end is connected to an elbow 9 and extends into a borehole 14. A plug plate 12 is installed at the place where the welded pipe 1 extends into the borehole 14. A threaded pipe joint 10 and a two-piece ball valve 11 are arranged on the plug plate 12. A flange 13 is arranged on the plug plate 12. The other end of the welded pipe 1 at the inlet end is connected to a water pump 15.

[0013] One end of the first reducer 3 is a circular opening with an outer diameter of 108 mm, and the other end is a circular opening with an outer diameter of 75 mm. The centers of the two are on the same straight line, and the shape is a regular frustum-shaped reducer;

[0014] One end of the eccentric reducer 4 is a circular opening with an outer diameter of 159 mm, and the other end is a circular opening with an outer diameter of 108 mm. Relative to the regular frustum-shaped reducer, the centers of the two openings are not on the same straight line, the circular bottom edges are on the same straight line, and the large and small diameters are in a gradual transition;

[0015] One end of the reducer 5 is a circular opening with an outer diameter of 219 mm, and the other end is a circular opening with an outer diameter of 159 mm. The centers of the two are on the same straight line, and the shape is a regular frustum-shaped reducer;

[0016] One end of the reducer 6 is a circular opening with an outer diameter of 400 mm for discharging materials, and the other end is a circular opening with an outer diameter of 219 mm connected to the tee. The centers of the two are on the same straight line, and the shape is a regular frustum-shaped reducer.

[0017] A flange 13 is installed at the opening of the borehole 14, and at the same time, the processed plug plate 12 is covered. The plug plate 12 has a 32 opening and a 108 opening. The 32 opening is inserted with a threaded pipe joint 10, and a two-piece ball valve 11 is installed on the threaded pipe joint 10; the welded pipe 1 is inserted into the 108 opening, and at the same time, the inserted vertical welded pipe 1 and the horizontal welded pipe 1 are connected with an elbow 9, and a flange 2 is welded at the other end; the tee 8, the reducer 5, and the eccentric reducer 4 are welded in sequence according to the same aperture, and it is ensured that the centers of the small diameters of the eccentric tee are on the same straight line. The reducer 6 is welded at the inlet of the tee 8, and a flange 2 is welded at the 108 outlet end.

[0018] The usage method of the sand-flushing and grouting fire extinguishing device includes the following steps;

[0019] The device has a sand inlet and a water inlet. The variable-diameter three-way 6 is the sand inlet, and the centrifugal pump 15 is the water inlet. During operation, first turn on the centrifugal pump 15 to let water in. After the water flow stabilizes, add sand (stones) from the top sand inlet. The flowing water will carry the sand (stones) into the inside of the borehole 14. The water will drain away due to the height difference, and the sand (stones) will rush in and settle in the goaf 17 and accumulate. The purpose of the two-piece ball valve 11 is to relieve pressure. When the pressure in the hole becomes too high during the later stage of perfusion, the two-piece ball valve 11 needs to be opened to relieve pressure to promote the progress of sand washing.

[0020] A fire extinguishing method for a room and pillar goaf fire extinguishing device includes the following steps;

[0021] (1) The ground borehole is used as a verification borehole in the early stage and as a sand filling borehole in the later stage;

[0022] The ground borehole 14 is constructed by the DTH hammer construction process. First, protect the φ530mm spiral pipe in the range of 1.5m deep in the surface soil sand layer, and then construct to a depth of 2m into the normal bedrock with a φ350mm borehole diameter. Through the drill cuttings ejected during drilling, determine whether it is a sand layer, a bedrock layer or a rock layer, and determine the depth within the normal bedrock roof. After determining the depth of the normal bedrock roof, lower the φ273mm casing pipe; then construct to the coal seam roof of the target goaf 17 with a φ250mm borehole diameter, and install a φ219mm casing pipe throughout the length of the borehole 14. The bottom end of the casing pipe is 2m away from the roof of the goaf 17; a gate valve should be installed at the orifice of the borehole 14, and the connection between the gate valve and the orifice is sealed with butter. When not grouting, close the valve. After lowering the casing pipe and the casing, the gap between the pipeline and the borehole 14 is sealed tightly with cement mortar. The specification of the cement mortar is M10; the weld strength must meet the welding grade requirements and be not less than Grade III;

[0023] (2) According to the borehole construction process in step (1), construct dense boreholes in the suspected fire area to find the exact fire source point. After the borehole construction is completed, lower the bundle tube to take gas and monitor abnormal fire gases, and use a temperature sensor to detect high-temperature points. After determining the high-temperature abnormal area 16, construct isolation boreholes 19 radiating 30m outward to prepare for subsequent fire extinguishing measure boreholes. At the same time, construct measure boreholes within the range of the isolation boreholes 19 to densify the boreholes. The determination basis for the borehole spacing is the width coverage range where the sand naturally sinks and finally accumulates after the water in the water flow drains out. According to on-site construction experience, the range that the sand from a single borehole can accumulate and fill after the water flow carries the sand into the goaf is 30m. If it exceeds 30m, another borehole is needed to supplement the coverage;

[0024] (3) After the construction of borehole 14 is completed, small stones are poured into the isolation borehole 19 using the sand-flushing and filling fire extinguishing device until the stones naturally accumulate to block the borehole and form a stone isolation wall. At this time, the fire area is jointly surrounded by the stones and the coal pillar 18. Subsequently, yellow sand is poured downward into the measure borehole 20 using the sand-flushing and filling fire extinguishing method. Because after the yellow sand is poured down with water, the water will flow out through the gaps between the stones, and the sand will gradually accumulate until it is filled up, forming a low-temperature environment that isolates oxygen. At this time, the air and temperature in the area have been replaced by the sand with water, thus achieving the purpose of extinguishing the fire.

[0025] Advantages of the present invention.

[0026] (1) Solved the problems of poor water injection effect for fire prevention and extinguishment in the overlying goaf, small coverage area, inability to reach the fire source point, and easy occurrence of water inrush in the lower goaf.

[0027] (2) Solved the problems of fire prevention and extinguishment by grouting, which cannot handle the fires on the high-position roof and roadway sides.

[0028] (3) Sand and stones are cheap, solving the problem of high cost of injecting colloid for fire extinguishment in a large-scale fire area.

[0029] (4) Compared with traditional cooling fire extinguishment, filling fire extinguishment also has the effect of air replacement and oxygen isolation, with high fire extinguishing efficiency.

[0030] (5) The filled area has a certain bearing capacity, which can prevent the coal pillar from collapsing due to spontaneous combustion and protect against the instantaneous instability and roof weighting caused by the large-area collapse of the roof, thus protecting the lives and property of personnel.

[0031] Sand is directly poured from the ground surface into the borehole. The sand moves downward by its own weight and is prone to accumulate and block the borehole due to local resistance in the borehole. Water is sucked into the centrifugal pump, pressurized, and then the pressurized water passes through the welded pipe, reducer, and threaded pipe joint in sequence. The pipe diameter gradually decreases through the reducer, and the water flow velocity increases due to the decrease in pipe diameter and enters the tee; sand is poured into the tee from the reducer. The sand falls into the tee under the action of gravity and meets the water flow with an increased velocity, and then merges with the water flow and passes through the reducer, eccentric reducer, and welded pipe into the borehole and then into the underground. The sand is directly washed into the goaf by the water. The water-mixed sand with pressure will have a wider diffusion area in the goaf than single sand pouring, and at the same time, it increases the sand pouring velocity and sand pouring volume, improving the filling effect and scope. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the sand-flushing and filling fire extinguishing device of the present invention.

[0033] Figure 2 It is a schematic diagram of the borehole of the present invention.

[0034] Figure 3 It is a schematic diagram of the borehole layout of the present invention.

[0035] Figure 4 Schematic diagram of the filling effect of the present invention.

[0036] Figure 5 Cross-sectional view of the filling effect.

[0037] Reference numerals:

[0038] 1. Welded pipe; 2. First flange; 3. First reducer; 4. Eccentric reducer; 5. Second reducer; 6. Third reducer; 7. First threaded pipe joint; 8. Tee; 9. Elbow; 10. Second threaded pipe joint; 11. Two-piece ball valve; 12. Plug plate; 13. Second flange; 14. Drilled hole; 15. Centrifugal pump. Specific embodiments

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0040] As Figure 1 shown: The working principle of the sand washing and filling fire extinguishing device is as follows:

[0041] The device is divided into a sand inlet and a water inlet. Among them, the third reducer 6 is the sand inlet, and the centrifugal pump 15 is the water inlet. During operation, first turn on the centrifugal pump 15 to let water in. After the water flow is stable, add sand (stones) from the top sand inlet. The flowing water will carry the sand (stones) into the drilled hole 14. The water will flow away due to the height difference, and the sand (stones) will rush in and settle in the goaf 17 and accumulate. The purpose of the two-piece ball valve 11 is to relieve pressure. When the pressure in the hole is too high during the later stage of filling, the two-piece ball valve 11 needs to be opened to relieve pressure to promote the sand washing progress.

[0042] Connection method: Install the second flange 13 at the mouth of the drilled hole 14 constructed, and at the same time cover the processed plug plate 12. The plug plate 12 has ports 32 and 108. The port 32 is inserted into the second threaded pipe joint 10, and the two-piece ball valve 11 is installed on the second threaded pipe joint 10. The welded pipe 1 is inserted into the port 108, and at the same time, the inserted vertical welded pipe 1 and the horizontal welded pipe 1 are connected by an elbow 9, and the other end is welded with the first flange 2. The tee 8, the second reducer 5, and the eccentric reducer 4 are welded in sequence according to the same aperture, and it is ensured that the centers of the small diameters of the eccentric tee are on the same straight line. The inlet of the tee 8 is welded with the third reducer 6, and the first flange 2 is welded at the 108 outlet end. As shown, insert one side of the inlet end and weld the first flange 2 at the tail to connect with the welded pipe 1. Connect the outlet of the centrifugal pump 15 with the welded pipe 1, and connect the inlet with the welded pipe 1 to the water source.

[0043] As Figure 2As shown: Fire prevention and extinguishing method for goaf overlying the close coal seam:

[0044] Usage method:

[0045] (1) The ground borehole 14 is used as a verification borehole 14 in the early stage and as a sand filling borehole in the later stage;

[0046] The ground borehole 14 is constructed by the DTH hammer construction process. Specifically, first, a φ530mm spiral pipe is used to protect the surface soil sand layer within a depth range of 1.5m. Then, a borehole with a φ350mm aperture is constructed into the normal bedrock for 2m. Through the drill cuttings ejected during drilling, it is determined whether it is a sand layer, a bedrock layer or a rock layer, and the depth within the normal bedrock roof is determined. After determining the depth of the normal bedrock roof, a φ273mm protection pipe is lowered. Then, a borehole with a φ250mm aperture is constructed to the roof of the 17th coal seam in the target goaf. A φ219mm casing is installed throughout the entire length of the borehole 14, and the bottom end of the casing is 2m away from the roof of the goaf 17. Among them, the φ530mm protection pipe is a spiral steel pipe with a wall thickness of 8mm, the φ273mm protection pipe is a seamless steel pipe with a wall thickness of 10mm, the φ219mm steel casing is a seamless steel pipe with a wall thickness of 6mm. A gate valve shall be installed at the orifice of the borehole 14, and the connection between the gate valve and the orifice shall be sealed with butter. The valve shall be closed when not grouting. After lowering the protection pipe and the casing, the gap between the pipeline and the borehole 14 shall be sealed tightly with cement mortar, and the specification of the cement mortar is M10. The weld strength must meet the welding grade requirements and be not less than Grade III. The borehole schematic diagram is shown in Figure 2 ;

[0047] (2) According to the borehole construction process in step (1), dense boreholes (60m * 60m) are constructed in the suspected fire area to find the accurate fire source point. After the borehole construction is completed, a bundle tube is lowered to extract gas to monitor abnormal fire gases (carbon monoxide greater than 100ppm), and a temperature sensor is used to detect high-temperature points (temperature greater than 35°C). After determining the high-temperature abnormal area 16, isolation boreholes 19 are constructed 30m outward for preparation for subsequent fire extinguishing measure boreholes. At the same time, measure boreholes are constructed within the range of the isolation boreholes 19 to densify the boreholes. The determination basis for the borehole spacing is the width coverage range of the natural settlement and final accumulation of sand after the water has drained. According to on-site construction experience, the range that the sand from a single borehole can accumulate and fill after the water with sand is brought into the goaf is 30m. If it exceeds 30m, another borehole is required to supplement the coverage (depending on the goaf crossroads corresponding to the minimum coal pillar. When the crossroads spacing is greater than 30m, additional boreholes are required, and at this time, the maximum borehole spacing should be less than 30m). The specific borehole layout schematic diagram is shown in Figure 3 ;

[0048] (3) After the construction of borehole 14 is completed, small stones are poured into the isolation borehole 19 by using a sand-flushing and filling fire extinguishing device until the stones naturally accumulate to block the borehole and form a stone isolation wall. At this time, the fire area is surrounded by stones and coal pillars. Subsequently, yellow sand is poured downward into the measure borehole 20 by using a sand-flushing and filling fire extinguishing device. Because after the yellow sand is poured down with water, the water will flow out through the gaps between the stones, and the sand will gradually accumulate until it is filled up, forming a low-temperature environment that isolates oxygen. At this time, the air and temperature in the area have been replaced by the sand with water, thus achieving the purpose of extinguishing the fire. The schematic diagram of the filling effect is shown in Figure 4 , and the cross-sectional view of the filling effect is shown in Figure 5 : Attached Figure 4 is a top-down cross-sectional view. The black part is the coal pillar 18 left over from room-and-pillar mining, and the white part is the goaf 17. The Figure 3 high-temperature abnormal area needs to be treated in this area. Through the isolation borehole 19 surrounding the high-temperature abnormal area, a sand-flushing and filling fire extinguishing device is used to fill the isolation borehole 19 with stones (stone particle size 5 - 20 mm), and the accumulated stones form a stone isolation area 22; for the measure borehole 20 in the high-temperature abnormal area 16, a sand-flushing and filling fire extinguishing device is used to fill it with sand to form a sand filling area 21. The function of the stone isolation area 22 is that because the density of the stones is large, the stability of the formed isolation accumulation zone is much greater than that of the sand. After the sand accumulates and spreads outward, it will stop moving when it encounters the stone isolation zone and gradually accumulate in thickness until it is filled up. And after the water flows away in the later stage, the sand will be blocked by the stone isolation wall and will not be taken away by the water, resulting in voids in the filling area, and the filling effect will be better. Figure 5 is the front cross-sectional view. On both sides are the isolation boreholes, and in the middle is the measure borehole 20. The stones injected into the isolation borehole 19 accumulate and fill up until they pile into the borehole. The sand injected into the measure borehole 20 accumulates and fills up until it piles into the borehole 14. The area filled with sand in the middle is the high-temperature abnormal area 16. The sand with water fills the entire high-temperature abnormal area due to the stone isolation zone, replacing the internal air and temperature, and forming an asphyxiating and cooling area inside, so that the high-temperature abnormal area cannot be further oxidized and is restored to the normal state.

Claims

1. A room and pillar goaf fire extinguishing device, characterized in that, Including a sand-flushing and filling fire extinguishing device, the sand-flushing and filling fire extinguishing device includes a welded pipe (1) at the inlet end. One end of the welded pipe (1) at the inlet end is connected to a tee (8) through an eccentric reducer (4) and a reducer two (5). The other end of the tee (8) is connected to the welded pipe (1) at the outlet end through a reducer two (5) and an eccentric reducer (4). The third port of the tee (8) is connected to a reducer three (6). The other end of the welded pipe (1) at the outlet end is connected to an elbow (9) and extends into a drill hole (14). A plug plate (12) is installed at the place where the welded pipe (1) extends into the drill hole (14). A threaded pipe joint (10) and a two-piece ball valve (11) are arranged on the plug plate (12). A flange two (13) is arranged on the plug plate (12). The other end of the welded pipe (1) at the inlet end is connected to a water pump (15).

2. The pillar-and-room goaf fire extinguishing device according to claim 1, wherein, One end of the first reducer (3) is a circular port with an outer diameter of 108 mm, and the other end is a circular port with an outer diameter of 75 mm. The centers of the two are on the same straight line, and the shape is a regular frustum reducer; One end of the eccentric reducer (4) is a circular port with an outer diameter of 159 mm, and the other end is a circular port with an outer diameter of 108 mm. Relative to the regular frustum reducer, the centers of the two ports are not on the same straight line, the circular bottom edges are on the same straight line, and the major and minor diameters are gradually changing; One end of the reducer two (5) is a circular port with an outer diameter of 219 mm, and the other end is a circular port with an outer diameter of 159 mm. The centers of the two are on the same straight line, and the shape is a regular frustum reducer; One end of the reducer three (6) is a circular port with an outer diameter of 400 mm for discharging materials, and the other end is a circular port with an outer diameter of 219 mm connected to the tee. The centers of the two are on the same straight line, and the shape is a regular frustum reducer.

3. The pillar-and-room goaf fire extinguishing device according to claim 1, characterized in that, A flange two (13) is installed at the drill hole (14) opening, and at the same time, the processed plug plate (12) is covered. A two-piece ball valve (11) is installed on the threaded pipe joint (10); the vertical welded pipe (1) and the horizontal welded pipe (1) are connected with an elbow (9), and a flange one (2) is welded at the other end; the tee (8), the reducer two (5), and the eccentric reducer (4) are welded in sequence according to the same aperture, and it is ensured that the centers of the small diameters of the eccentric tee are on the same straight line, and a reducer three (6) is welded at the inlet of the tee (8).

4. The pillar mining goaf fire extinguishing device according to claim 1, characterized in that, The usage method of the sand-flushing and filling fire extinguishing device includes the following steps; The device is divided into a sand inlet and a water inlet. Among them, the reducer three (6) is the sand inlet, and the water pump (15) is the water inlet. During operation, first turn on the water pump (15) to let water in. After the water flow is stable, add sand from the top sand inlet. The flowing water will carry the sand into the interior of the drill hole (14). The water will be lost due to the height difference, and the sand will rush in and then precipitate into the goaf (17) and accumulate; the purpose of the two-piece ball valve (11) is to relieve pressure. When the pressure in the hole is too high during the later stage of perfusion, the two-piece ball valve (11) needs to be opened to relieve pressure to promote the sand-flushing progress.

5. A fire extinguishing method for a room and pillar goaf fire extinguishing device according to any one of claims 1-4, characterized in that, Including the following steps; (1) It is used as a verification drill hole in the early stage on the ground and as a sand-filling hole in the later stage; The surface drilling hole (14) is constructed by the DTH hammer construction method. First, the φ530mm spiral pipe is used to protect the surface soil sand layer within a depth range of 1.5m. Then, the hole with a diameter of φ350mm is constructed to a depth of 2m into the normal bedrock. Through the drill cuttings ejected during drilling, it is determined whether it is a sand layer, a bedrock layer or a rock layer, and the depth within the normal bedrock roof is determined. After determining the depth of the normal bedrock roof, a φ273mm casing pipe is lowered; then, the hole with a diameter of φ250mm is constructed to the coal seam roof of the target goaf (17). A φ219mm casing pipe is installed throughout the length of the drilling hole (14), and the bottom end of the casing pipe is 2m away from the roof of the goaf (17); a gate valve shall be installed at the orifice of the drilling hole (14). The connection between the gate valve and the orifice is sealed with butter. When not grouting, the valve is closed. After lowering the casing pipe and the casing, the gap between the pipeline and the drilling hole (14) is sealed tightly with cement mortar, and the specification of the cement mortar is M10; the weld strength must meet the welding grade requirements and be not less than Grade III; (2) According to the drilling construction technology in step (1), dense drilling holes are constructed in the suspected area of the fire area to find the precise fire source point. After the drilling construction is completed, a bundle tube is lowered to collect gas to monitor abnormal fire gases, and a temperature sensor is used to detect high-temperature points. After determining the high-temperature abnormal area (16), isolation drilling holes (19) are constructed 30m outward for preparation for subsequent fire extinguishing measure drilling. At the same time, measure drilling holes are constructed within the range of the isolation drilling holes (19) to increase the drilling hole density. The determination basis for the drilling hole spacing is the width coverage range of the sand pile formed by the natural settlement of the sand after the water has drained. According to the on-site construction experience, the range that the sand of a single drilling hole can accumulate and fill after the water with sand is brought into the goaf is 30m. If it exceeds 30m, another drilling hole is required to supplement the coverage; (3) After the construction of the drilling hole (14) is completed, small stones are poured into the isolation drilling hole (19) by using a sand flushing and filling fire extinguishing device until the stones naturally accumulate to block the drilling hole and form a stone isolation wall. At this time, the fire area is jointly surrounded by stones and coal pillars (18). Subsequently, yellow sand is poured downward in the measure drilling hole (20) by using a sand flushing and filling fire extinguishing device. Because after the yellow sand is poured down with water, the water will flow out from the gaps between the stones, and the sand will gradually accumulate until it is filled, forming a low-temperature environment that isolates oxygen. At this time, the air and temperature in the area have been replaced by the sand with water, thus achieving the purpose of extinguishing the fire.

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