Underground goaf gangue backfilling structure, backfilling method and used slurry

Abstract

The invention relates to the technical field of mine goaf filling, and provides an underground goaf gangue backfilling structure, a backfilling method and used slurry. Comprising at least three first drill holes used for grouting, the at least three first drill holes extend along a bottom plate of a working face roadway, and the at least three first drill holes are communicated with a goaf; the at least five second drill holes are used for grouting, extend along the working face and are communicated with the goaf; and the at least one third drill hole is used for gas drainage, extends along the top plate of the working face and is communicated with the goaf. The method has the beneficial effects that gangue backfilling is carried out on the goaf behind the working face through the grouting pipelines in the first drill hole and the second drill hole. After goaf gangue is backfilled, the third drill hole can be connected with the water-ring vacuum pump to complete pumping and discharging of the easily-reactive gas, the influence of the easily-reactive gas on the working face and the adjacent working face is reduced, and safe production of a mine is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of filling the goaf of a mine, and in particular to a gangue backfilling structure and a backfilling method for an underground goaf and slurry used therein. Background Art

[0002] Coal mining produces a large number of goafs, which will bring a series of problems to economic and social development. More than 95% of my country's coal mining is produced by underground mines, and most of them use longwall mining. With the advancement of coal mining technology, the speed of coal mining is increasing day by day, resulting in the continuous expansion of the area of ​​coal goafs and the formation of more and more extensive subsidence areas. The subsidence area will cause great damage to agriculture, industry and the lives of local residents around the mining area, and also restrict the sustainable development of coal mining. In terms of ecological and environmental impact, coal goafs have destroyed the stratum structure, caused the groundwater level to drop, and severely damaged the surface vegetation. Coal mine goafs have destroyed the ecological environment, restricted the sustainable development of the economy and society, and urgently need to be effectively governed.

[0003] Coal mining also produces a large amount of gangue. A large amount of gangue is piled on the surface, occupying a large amount of land, burying and destroying the original landform, making arable land resources more scarce. In addition, a large amount of dust is generated during the discharge of gangue, and toxic substances are generated during the spontaneous combustion process, which leads to slow plant growth and a reduction in plant species, causing serious damage to the ecological environment of the mining area. The sulfide in the gangue generates a large amount of heat when oxidized in the air. When the temperature reaches the ignition point of the gangue, the gangue will spontaneously combust, and the spontaneous combustion of the gangue mountain may last for many years. The spontaneous combustion of gangue produces toxic gases such as sulfur dioxide. The emission of these toxic gases reduces the surrounding air quality, which not only affects the health of surrounding residents but also damages the surrounding ecological environment, causing crop yield reduction or even death.

[0004] Traditional methods of gangue treatment include multiple sorting and refining of rare metal minerals; making bricks, cement and ceramics from gangue; generating electricity from gangue; producing aluminum sulfate from gangue; producing compound fertilizer from gangue, etc. Based on the current research status, coal mining enterprises, as the direct source of gangue, have a very low effective utilization rate of gangue, and most of it is transported to gangue sites for ground disposal, which has little effect on improving the current environmental pollution situation. It is urgent to explore new methods and new ways to utilize solid waste resources to enable the sustainable green development of mines.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The purpose of the present invention is to provide a waste rock backfill structure, a backfill method and a slurry used in an underground goaf area, so as to solve the technical problems existing in the prior art.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is: a waste rock backfill structure in an underground goaf, comprising:

[0008] At least three first boreholes for grouting, at least three of the first boreholes extending along the floor of the working face tunnel, and at least three of the first boreholes communicating with the goaf;

[0009] At least five second boreholes for grouting, at least five of the second boreholes extending along the working face, and at least five of the second boreholes communicating with the goaf;

[0010] At least one third borehole for gas extraction, at least one of the third boreholes extending along the top plate of the working face, and at least one of the third boreholes communicating with the goaf;

[0011] The terminal height of at least one of the third boreholes is greater than the terminal heights of at least five of the second boreholes.

[0012] In an optional embodiment, a drilling site is arranged near the stop-production line of the working face, and the first borehole, the second borehole, and the third borehole extend from the stop-production line.

[0013] In an optional embodiment, the number of the first boreholes is three, the number of the second boreholes is five, and the number of the third borehole is one.

[0014] In an optional embodiment, the horizontal distances between the three first boreholes and the tunnel are L 1-1 , L 1-2 , L 1-3 The vertical distances between the three first boreholes and the tunnel are H 1-1 , H 1-2 , H 1-3 ; Among them, H 1-1 With H 1-3 are at the same height;

[0015] The horizontal distances between the five second boreholes and the tunnel are L 2-1 , L 2-2 , L 2-3 , L 2-4 , L 2-5 , the vertical distances between the second borehole and the tunnel are H 2-1 , H 2-2 , H 2-3 , H 2-4 , H 2-5 ; Among them, H 2-1 With H 2-5 For the same height, H 2-2 With H 2-4 are at the same height;

[0016] The horizontal distance between the third borehole and the tunnel is L3, and the vertical distance between the third borehole and the tunnel is H3.

[0017] In an optional embodiment, a gas extraction pipeline is arranged in the third borehole, and the extraction pipeline is connected to a water ring vacuum pump; a grouting pipeline is provided in each of the first borehole and the second borehole, and the grouting pipeline is connected to a mining pump.

[0018] In an optional embodiment, each of the first borehole, the second borehole, and the third borehole is located at the end of the stop-production line for hole expansion, and each of the expanded holes is sealed using a sealing device.

[0019] 7. The underground goaf waste rock backfill structure as described in claim 6 is characterized in that the sealing device includes an inner fixed ring, and the inner fixed ring is provided with a grouting hole and an exhaust hole.

[0020] An inner airbag is arranged outside the inner fixed ring, and an outer protective sleeve is arranged outside the inner airbag; an inflation port and a pressure sensor are arranged on the inner airbag, and the outer protective sleeve is interference-fitted with the inner diameter of the expanded hole after the inner airbag is inflated.

[0021] On the other hand, the present invention also provides a backfilling method using the underground goaf waste rock backfilling structure as described above, comprising the following steps:

[0022] S1: After the working face is arranged, a drilling site is arranged near the stop line of the working face, wherein the drilling site close to the working face is a drilling arrangement area;

[0023] S2: setting a first borehole, a second borehole, and a third borehole respectively along the borehole arrangement area toward the goaf area of ​​the working face;

[0024] S3: expanding the first borehole, the second borehole, and the third borehole, and sealing the boreholes with a sealing device; after the inner airbag in the sealing device is inflated, the outer protective cover is interference-fitted with the expanded borehole, and a pressure sensor is implemented to monitor the pressure of the inner airbag;

[0025] S4: As the working face advances, slurry is injected into the goaf behind the working face through the grouting pipelines in the first borehole and the second borehole to perform gangue backfilling;

[0026] S5: After the goaf is backfilled with waste rock, the gas in the goaf is extracted through the third borehole.

[0027] On the other hand, the present invention also provides a slurry used in the backfilling method as described above, comprising: a gangue mass concentration of 85%;

[0028] The remaining components are calculated in percentage by mass, including 10%-30% fly ash, 10%-20% cement, 0.5%-1.5% water reducing agent, and 2%-6% water glass.

[0029] The beneficial effects of the present invention are:

[0030] As the working face advances, slurry is injected into the goaf behind the working face through the grouting pipelines in the first and second boreholes to backfill the goaf with waste rock. After the goaf is backfilled with waste rock, the reactive gas in the space will migrate upward along the collapse zone and crack zone above the goaf due to its own physical properties and the spatial range in the fixed space. The third borehole can be connected to a water ring vacuum pump to complete the extraction of the reactive gas, reduce the impact of the reactive gas on the working face and adjacent working faces, and ensure the safe production of the mine. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 A schematic diagram (side view) of a waste rock backfill structure for an underground goaf provided by an embodiment of the present invention.

[0033] Figure 2 A schematic diagram of the sealing arrangement of the waste rock backfill structure in the lower goaf provided by one embodiment of the present invention.

[0034] Figure 3 The present invention is a schematic diagram of a sealing device for a gangue backfill structure in an underground goaf provided in one embodiment of the present invention.

[0035] Figure 4 The figure is a schematic structural diagram of an inner fixed ring in a gangue backfill structure of an underground goaf provided in one embodiment of the present invention.

[0036] Figure 5 It is a side view of the first, second and third boreholes in the underground goaf waste rock backfill structure provided in one embodiment of the present invention.

[0037] Figure 6 It is a top view of the first, second and third boreholes in the underground goaf waste rock backfill structure provided in one embodiment of the present invention.

[0038] Among them, the figure markings are: 1-tunnel, 2-drilling site, 3-bottom plate, 4-goaf, 5-top plate, 6-stop mining line, 7-outer protective cover, 8-inner air bag, 9-inflating port, 10-pressure sensor, 11-inner fixing ring, 12-grouting hole, 13-exhaust hole, 14-coal rock mass, 15-first borehole, 16-second borehole, 17-third borehole. DETAILED DESCRIPTION

[0039] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] It should be noted that when a component is referred to as being "fixed to" or "affixed to" another component, it may be directly or indirectly located on the other component. When a component is referred to as being "connected to" another component, it may be directly or indirectly connected to the other component. The directions or positions indicated by the terms "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positions shown in the accompanying drawings and are only for the convenience of description and cannot be understood as limitations on the present technical solution. The terms "first" and "second" are only used for the convenience of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. "Multiple" means two or more, and "several" means any number including one, unless otherwise clearly and specifically defined.

[0041] Please refer to the attached Figure 1-6 The purpose of this embodiment is to provide a waste rock backfill structure for underground goaf, which is characterized by comprising:

[0042] At least three first boreholes 15 for grouting, the at least three first boreholes 15 extending along the floor of the working face tunnel, and the at least three first boreholes 15 communicating with the goaf;

[0043] At least five second boreholes 16 for grouting, the at least five second boreholes 16 extending along the working face, and the at least five second boreholes 16 communicating with the goaf;

[0044] At least one third borehole 17 for gas extraction, at least one third borehole 17 extending along the top plate of the working face, at least one third borehole 17 communicating with the goaf;

[0045] The end height of the at least one third bore hole 17 is greater than the end heights of the at least five second bore holes 16 .

[0046] As the working face advances, slurry is injected into the goaf behind the working face through the grouting pipelines of the first borehole 15 and the second borehole 16 to backfill the goaf with waste rock. After the goaf is backfilled with waste rock, the reactive gas in the space will migrate upward along the collapse zone and the crack zone above the goaf due to its own physical properties and the spatial range in the fixed space. The third borehole 17 can be connected to a water ring vacuum pump to complete the extraction of the reactive gas, thereby reducing the impact of the reactive gas on the working face and the adjacent working face, and ensuring the safe production of the mine.

[0047] In this embodiment, the drilling site 2 is arranged near the stop line 6 of the working face, and the first borehole 15, the second borehole 16, and the third borehole 17 extend from the stop line 6. The number of the first boreholes 15 is three, the number of the second boreholes 16 is five, and the number of the third borehole 17 is one. The horizontal distances between the three first boreholes 15 and the roadway are L 1-1 , L 1-2 , L 1-3 The vertical distances between the three first boreholes 15 and the tunnel are H 1-1 , H 1-2 , H 1-3 ; Among them, H 1-1 With H 1-3 The horizontal distances between the five second boreholes 16 and the tunnel are L 2-1 , L 2-2 , L 2-3 , L 2-4 , L 2-5 , the vertical distances between the second borehole and the tunnel are H 2-1 , H 2-2 , H 2-3 , H 2-4 , H 2-5 ; Among them, H 2-1 With H 2-5 For the same height, H 2-2 With H 2-4 They are arranged at the same height along the trapezoidal waistline; the horizontal distance between a third borehole 17 and the tunnel is L3, and the vertical distance between the third borehole 17 and the tunnel is H3.

[0048] In an optional embodiment, the horizontal distance from the end of the first borehole 15 to the borehole arrangement area is a first length, and the vertical distance from the end of the first borehole 15 to the borehole arrangement area is a first height. The horizontal distance from the end of the second borehole 16 to the borehole arrangement area is a second length, and the vertical distance from the end of the second borehole 16 to the borehole arrangement area is a second height. The horizontal distance from the end of the third borehole 17 to the borehole arrangement area is a third length, and the vertical distance from the end of the third borehole 17 to the borehole arrangement area is a third height. Preferably, the first height is the initial height of the bottom plate damage zone, the second height is the height of the top plate collapse zone, and the third height is the top plate crack height.

[0049] Furthermore, a gas extraction pipeline is arranged in the third borehole 17, and the extraction pipeline is connected to a water ring vacuum pump; a grouting pipeline is arranged in each first borehole 15 and the second borehole 16, and the grouting pipeline is connected to a mining pump. Each first borehole 15, the second borehole 16, and the third borehole 17 are located at the end of the stop-mining line 6 for hole expansion, and each expanded hole is sealed by a sealing device. The sealing device includes an inner fixed ring 11, and a grouting hole 12 and an exhaust hole 13 are arranged on the inner fixed ring 11; an inner air bag 8 is arranged outside the inner fixed ring 11, and an outer protective cover 7 is arranged outside the inner air bag 8; an inflation port 9 and a pressure sensor 10 are arranged on the inner air bag 8, and the outer protective cover 7 is interference fit with the inner diameter of the expanded hole after the inner air bag 8 is inflated. In an optional embodiment, the hole expansion includes the first, second, and third boreholes being expanded to a fourth length respectively. The length of the inner fixed ring 11 is not less than two-thirds of the fourth length.

[0050] The backfilling method using the underground goaf waste rock backfilling structure comprises the following steps:

[0051] S1: After the working face is arranged, a drilling site 2 is arranged near the stop line 6 of the working face, wherein the drilling site 2 near the working face is the drilling arrangement area;

[0052] S2: a first borehole 15, a second borehole 16, and a third borehole 17 are respectively arranged along the borehole arrangement area toward the goaf of the working face;

[0053] S3: Expand the first borehole 15, the second borehole 16, and the third borehole 17, and use a sealing device to complete the sealing; after the inner airbag 8 in the sealing device is inflated, the outer protective cover 7 and the expanded hole are interference fit, and the pressure sensor 10 monitors the pressure of the inner airbag 8;

[0054] S4: As the working face advances, slurry is injected into the goaf behind the working face through the grouting pipelines in the first borehole 15 and the second borehole 16 to perform gangue backfilling;

[0055] S5: After the goaf is backfilled with waste rock, the gas in the goaf is extracted through the third borehole 17.

[0056] The slurry used in the backfilling method includes: gangue mass concentration of 85%; other components are calculated by mass percentage; among them, 10%-30% fly ash, 10%-20% cement, 0.5%-1.5% water reducing agent, and 2%-6% water glass.

[0057] In an optional embodiment, the present invention further provides a slurry, wherein the gangue mass concentration of the slurry is fixed at 85%, and the remaining components are calculated by mass percentage, including:

[0058] 10%~30% fly ash / coal gangue powder, 10%~20% cement, 0.5%~1% water reducer, 2%~6% water glass.

[0059] The material obtained in the embodiment was tested for compressive strength according to GB / T 23561.7-2009, for material fluidity according to GB / T50080-2016, and for elastic modulus according to GB / T 23561.8-2024.

[0060] Among them, the particle size of the coal gangue powder is less than or equal to 75μm, and / or the content of silicon oxide in the coal gangue powder exceeds 50%, and the content of aluminum oxide exceeds 30%, and / or the particle size of the fly ash is 40μm, and / or the porosity of the fly ash is 5-8%, and / or the cement is national standard ordinary P.O42.5 cement, and / or the water reducer is a polycarboxylic acid high-efficiency water reducer.

[0061] Embodiment 2

[0062] 30% fly ash, 10% cement, 1.5% water reducer, 2% water glass, fluidity 330mm, 7d compressive strength 2.50MPa, 28d compressive strength 5.03MPa, 28d elastic modulus 433.25MPa,

[0063] Embodiment 3

[0064] 30% fly ash, 15% cement, 0.5% water reducer, 4% water glass, fluidity 175mm, 7d compressive strength 8.39MPa, 28d compressive strength 8.45MPa, 28d elastic modulus 992.31MPa,

[0065] Embodiment 4

[0066] 20% fly ash, 10% cement, 1.0% water reducer, 2% water glass, fluidity 210mm, 7d compressive strength 3.84MPa, 28d compressive strength 4.13MPa, 28d elastic modulus 514.12MPa,

[0067] Embodiment 5

[0068] 30% coal gangue, 10% cement, 1.5% water reducer, 2% water glass, fluidity 228mm, 7d compressive strength 2.15MPa, 28d compressive strength 3.89MPa, 28d elastic modulus 412.30MPa,

[0069] Embodiment 6

[0070] 30% coal gangue, 15% cement, 0.5% water reducer, 3% water glass, fluidity 144mm, 7d compressive strength 3.23MPa, 28d compressive strength 6.54MPa, 28d elastic modulus 502.17MPa,

[0071] Embodiment 7

[0072] 20% coal gangue, 10% cement, 1.0% water reducer, 4% water glass, fluidity 173mm, 7d compressive strength 2.54MPa, 28d compressive strength 2.26MPa, 28d elastic modulus 321.83MPa,

[0073] As shown in Examples 2 to 4, the compressive strength is significantly affected by the water reducing agent. Comparing Examples 2-5, 3-6, and 4-7, the fly ash content is stronger than the gangue content in terms of overall performance, and its fluidity is significantly improved compared with the prior art. The materials used are environmentally friendly and safe, reducing the burden of environmental pollution caused by gangue.

[0074] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A waste rock backfill structure for underground goaf, characterized in that: include: At least three first boreholes (15) for grouting, at least three of the first boreholes (15) extending along the floor of the working face tunnel, and at least three of the first boreholes (15) communicating with the goaf; At least five second boreholes (16) for grouting, wherein at least five of the second boreholes (16) extend along the working face, and at least five of the second boreholes (16) are connected to the goaf; at least one third borehole (17) for gas extraction, at least one of the third boreholes (17) extending along the top plate of the working face, and at least one of the third boreholes (17) communicating with the goaf; The terminal height of at least one of the third bore holes (17) is greater than the terminal heights of at least five of the second bore holes (16).

2. The underground goaf waste rock backfill structure according to claim 1, characterized in that: A drilling site (2) is arranged near the stop-production line (6) of the working face, and the first borehole (15), the second borehole (16), and the third borehole (17) extend from the stop-production line (6).

3. The underground goaf waste rock backfill structure according to claim 2, characterized in that: The number of the first bore holes (15) is three, the number of the second bore holes (16) is five, and the number of the third bore hole (17) is one.

4. The underground goaf waste rock backfill structure as claimed in claim 3, characterized in that: The horizontal distances between the three first boreholes (15) and the tunnel are L 1-1 , L 1-2 , L 1-3 The vertical distances between the three first boreholes (15) and the tunnel are H 1-1 , H 1-2 , H 1-3 ; Among them, H 1-1 With H 1-3 are at the same height; The horizontal distances between the five second boreholes (16) and the tunnel are L 2-1 , L 2-2 , L 2-3 , L 2-4 , L 2-5 , the vertical distances between the second borehole and the tunnel are H 2-1 , H 2-2 , H 2-3 , H 2-4 , H 2-5 ; Among them, H 2-1 With H 2-5 For the same height, H 2-2 With H 2-4 are at the same height; The horizontal distance between the third borehole (17) and the tunnel is L3, and the vertical distance between the third borehole (17) and the tunnel is H3.

5. The underground goaf waste rock backfill structure as claimed in claim 4, characterized in that: A gas extraction pipeline is arranged in the third borehole (17), and the extraction pipeline is connected to a water ring vacuum pump; a grouting pipeline is arranged in each of the first borehole (15) and the second borehole (16), and the grouting pipeline is connected to a mining pump.

6. The underground goaf waste rock backfill structure according to claim 4, characterized in that: Each of the first borehole (15), the second borehole (16), and the third borehole (17) is located at the end of the stop-production line (6) for hole expansion, and each of the expanded holes is sealed using a hole sealing device.

7. The underground goaf waste rock backfill structure according to claim 6, characterized in that: The sealing device comprises an inner fixing ring (11), and the inner fixing ring (11) is provided with a grouting hole (12) and an exhaust hole (13).

8. The underground goaf waste rock backfill structure according to claim 7, characterized in that: An inner airbag (8) is arranged outside the inner fixed ring (11), and an outer protective sleeve (7) is arranged outside the inner airbag (8); an inflation port (9) and a pressure sensor (10) are arranged on the inner airbag (8), and the outer protective sleeve (7) is interference-fitted with the inner diameter of the expanded hole after the inner airbag (8) is inflated.

9. A backfilling method using the underground goaf waste rock backfilling structure according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1: After the working face is arranged, a drilling site (2) is arranged near the stop line (6) of the working face, wherein the drilling site (2) close to the working face is a drilling arrangement area; S2: Arranging a first borehole (15), a second borehole (16), and a third borehole (17) along the borehole arrangement area toward the goaf of the working face; S3: expanding the first borehole (15), the second borehole (16), and the third borehole (17), and sealing the boreholes using a sealing device; after the inner airbag (8) in the sealing device is inflated, the outer protective cover (7) is interference-fitted with the expanded boreholes, and a pressure sensor (10) is used to monitor the pressure of the inner airbag (8); S4: As the working face advances, slurry is injected into the goaf behind the working face through the grouting pipelines in the first borehole (15) and the second borehole (16) to perform gangue backfilling; S5: After the goaf is backfilled with waste rock, the gas in the goaf is extracted through the third borehole (17).

10. A slurry for use in the backfilling method according to claim 9, characterized in that: include: The mass concentration of gangue is 85%; The remaining components are calculated in percentage by mass, including 10%-30% fly ash, 10%-20% cement, 0.5%-1.5% water reducing agent, and 2%-6% water glass.

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