A method for controlling air leakage in a gob area

Abstract

The present invention discloses a method for controlling air leakage in a goaf. The method cuts off the connection between the goaf and the coal mining face by constructing a drift partition, and increases the air pressure in the heat dissipation zone by pressing fresh air into the heat dissipation zone, thereby forming a pressure-equalizing zone in the heat dissipation zone and making the air pressure in the heat dissipation zone higher than that in the oxidation zone. This can prevent the gas in the oxidation zone from flowing into the heat dissipation zone, block the gas flow path in the oxidation zone and the asphyxiation zone, and effectively reduce surface air leakage in the oxidation zone and the asphyxiation zone.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mining, in particular to a method for controlling air leakage in a goaf. Background Art

[0002] During the mining process, coal mines need mine ventilation to deliver fresh air to the underground, remove toxic and harmful gases and dust, and regulate the underground climate environment.

[0003] Mine ventilation is generally carried out by the main ventilation fan to deliver fresh air to the underground. The circulation path of the fresh air is: air intake tunnel - air intake chute - coal mining working face - return air chute - return air tunnel.

[0004] After coal mining, a goaf forms behind the working face. Above this goaf, caving zones, fissure zones, and curved subsidence zones form. Because most coal seams in Northwest my country are shallow, these fissure zones can reach the surface. The negative pressure generated underground in the coal mine can lead to significant air leakage through these fissures. Based on oxygen concentration, the goaf can be divided into a heat dissipation zone, an oxidation zone, and a suffocation zone, moving backward from the working face. Excessive oxygen levels in the oxidation zone can cause spontaneous combustion.

[0005] The existing technology mainly adopts the method of filling and sealing the surface cracks to prevent fresh air from leaking into the goaf through the cracks.

[0006] Because it is impossible to completely seal all surface cracks, some are always left unsealed, and new cracks are created as the coal mining face advances. Since the air inlet and return chutes in the goaf are connected to the coal mining face, air from the asphyxiation and oxidation zones enters the heat dissipation zone through the air inlet and return chutes, and then circulates through the corners of the coal mining face, forming ventilation paths in the goaf. Fresh air always leaks into the goaf through the cracks, which is not conducive to controlling air leakage in the goaf.

[0007] In view of this, it is necessary to provide a method for controlling air leakage in goaf that has good effect in preventing surface air leakage. Summary of the Invention

[0008] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for controlling air leakage in goafs which has a good effect in preventing surface air leakage.

[0009] The technical solution of the present invention provides a method for controlling air leakage in goaf, comprising the following steps:

[0010] S01: excavating an auxiliary tunnel outside the return air chute in advance, and excavating a plurality of spaced connecting tunnels between the auxiliary tunnel and the return air chute;

[0011] A ventilation pipe is pre-buried in each of the connecting tunnels, and a valve is installed on the ventilation pipe;

[0012] A main air supply pipe is installed in the auxiliary lane, and the main air supply pipe is connected to each of the ventilation pipes;

[0013] S02: Install a local ventilator in the main air inlet lane, and connect the air inlet end of the main air supply pipe to the local ventilator;

[0014] S03: As the coal mining face advances toward the air intake tunnel, tunnel partitions are constructed in the air intake tunnel and the return air tunnel at preset intervals, and each ventilation pipe is located between the two preceding and following tunnel partitions;

[0015] In a direction opposite to the excavation direction of the coal mining working face, the goaf is divided into a heat dissipation zone, an oxidation zone and a suffocation zone according to the oxygen concentration;

[0016] S04: opening the valve on the ventilation pipe leading to the heat dissipation belt, and keeping the valves on the other ventilation pipes closed;

[0017] Supplying air to the heat dissipation belt through the local ventilator to increase the pressure until the pressure difference between the heat dissipation belt and the ground is within a preset range;

[0018] The air pressure in the heat dissipation zone is greater than the air pressure in the oxidation zone.

[0019] In one of the optional technical solutions, an underground air pressure sensor is installed in the heat dissipation belt, and a ground air pressure sensor is installed on the ground;

[0020] The local ventilator is a variable frequency fan;

[0021] The underground air pressure sensor and the surface air pressure sensor are respectively connected to the local ventilator signal;

[0022] When the pressure difference between the heat dissipation belt and the ground is less than a preset range, the local ventilator increases its speed to increase the air supply volume;

[0023] When the pressure difference between the heat dissipation belt and the ground is greater than a preset range, the local ventilator reduces its rotation speed and the air supply volume.

[0024] In one of the optional technical solutions, a plurality of local fans arranged in parallel are installed in the air inlet tunnel.

[0025] In one of the optional technical solutions, the surface cracks in the area corresponding to the oxidation zone are sealed.

[0026] In one of the optional technical solutions, surface cracks are sealed immediately behind the coal mining face.

[0027] In one of the optional technical solutions, in the excavation direction along the coal mining working face, the heat dissipation zone has at least two sections of longitudinal partitions.

[0028] In one of the optional technical solutions, one of the connecting lanes in the heat dissipation zone is adjacent to the oxidation zone.

[0029] In one of the optional technical solutions, the space of the heat dissipation belt near the coal mining working face is filled or forcibly topped out to block the return air corner.

[0030] In one of the optional technical solutions, a working face ventilator is installed in the air inlet tunnel, and air is supplied to the air inlet chute through the working face ventilator to increase the air pressure in the coal mining working face.

[0031] In one of the optional technical solutions, an adjustable air window is installed in the return air chute.

[0032] The above technical solution has the following beneficial effects:

[0033] The method for controlling air leakage in the goaf provided by the present invention cuts off the connection between the goaf and the coal mining face by constructing a drift partition, and increases the air pressure in the heat dissipation zone by pressing fresh air into the heat dissipation zone, thereby forming a pressure-equalizing zone in the heat dissipation zone and making the air pressure in the heat dissipation zone higher than that in the oxidation zone, thereby preventing the gas in the oxidation zone from flowing into the heat dissipation zone, blocking the gas flow path in the oxidation zone and the asphyxiation zone, and effectively reducing surface air leakage in the oxidation zone and the asphyxiation zone.

[0034] The method for controlling air leakage in the goaf provided by the present invention not only enhances the heat dissipation effect of the heat dissipation belt by pressing fresh air into the heat dissipation belt, but also suppresses air leakage in the oxidation belt and the asphyxiation belt, thereby achieving the effect of stopping air leakage in the oxidation belt and the asphyxiation belt by pressing air in the heat dissipation belt. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The disclosure of the present invention will become more easily understood with reference to the accompanying drawings. It should be understood that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. In the drawings:

[0036] Figure 1 A system schematic diagram of a method for controlling air leakage in goaf provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0037] The following further describes specific embodiments of the present invention with reference to the accompanying drawings. Like components are denoted by like reference numerals. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, and the terms "inward" and "outward" refer to directions toward or away from the geometric center of a particular component, respectively.

[0038] like Figure 1 As shown, a method for controlling air leakage in a goaf provided by one embodiment of the present invention includes the following steps:

[0039] S01: excavate an auxiliary tunnel 5 outside the return air chute 4 in advance, and excavate a plurality of connecting tunnels 6 arranged at intervals between the auxiliary tunnel 5 and the return air chute 4.

[0040] A ventilation pipe 12 is pre-buried in each connecting tunnel 6 , and a valve is installed on the ventilation pipe 12 .

[0041] A main air supply pipe 13 is installed in the auxiliary tunnel 5 , and the main air supply pipe 13 is connected to each ventilation pipe 12 .

[0042] S02: A local ventilator 14 is installed in the air inlet tunnel 1, and the air inlet end of the main air supply pipe 13 is connected to the local ventilator 14.

[0043] S03: As the coal mining face 7 advances toward the air intake tunnel 1, tunnel partitions 11 are constructed in the air intake tunnel 3 and the return air tunnel 4 at preset intervals, and each ventilation pipe 12 is located between the front and rear tunnel partitions 11.

[0044] In a direction opposite to the excavation direction of the coal mining face 7, the goaf is divided into a heat dissipation zone 8, an oxidation zone 9 and a suffocation zone 10 according to the oxygen concentration.

[0045] S04: Open the valve on the ventilation pipe 12 leading to the heat dissipation belt 8, and keep the valves on the other ventilation pipes 12 closed.

[0046] Air is supplied to the heat dissipation belt 8 by the local ventilator 14 to increase the pressure until the pressure difference between the heat dissipation belt 8 and the ground is within a preset range.

[0047] The air pressure in the heat dissipation zone 8 is greater than the air pressure in the oxidation zone 9 .

[0048] During coal mining, a main air intake tunnel 1, a return air tunnel 2, an air intake chute 3, and a return air chute 4 are typically arranged. The main air intake tunnel 1 and the return air tunnel 2 are located in front of the coal mining face 7, while the air intake chute 3 and the return air chute 4 are located on the left and right sides of the coal mining face 7. The air intake chute 3 is connected to the main air intake tunnel 1, and the return air chute 4 is connected to the return air tunnel 2. A main ventilation fan is located in the main air intake tunnel 1 to supply air to the main air intake tunnel 1. Fresh air passes through the main air intake tunnel 1 and the air intake chute 3 and enters the coal mining face 7 before being discharged through the return air chute 4 and the return air tunnel 2.

[0049] The method for controlling air leakage in the goaf provided by the present invention is to excavate an auxiliary tunnel 5 on the outside of the return air chute 4 in advance. The auxiliary tunnel 5 is basically parallel to the return air chute 4 and is also used for return air to the coal mining face 7. A plurality of spaced connecting tunnels 6 are excavated between the auxiliary tunnel 5 and the return air chute 4. A ventilation pipe 12 is pre-buried in each connecting tunnel 6. The ventilation pipe 12 has a valve to control the opening and closing of the ventilation pipe 12. The diameter of the ventilation pipe 12 is greater than 300 mm. A main air supply pipe 13 is installed in the auxiliary tunnel 5, and the main air supply pipe 13 is connected to each ventilation pipe 12. A local ventilator 14 is pre-installed in the air inlet tunnel 1 to supply air to a local location underground. The air inlet end of the main air supply pipe 13 is connected to the local ventilator 14.

[0050] As the coal mining face 7 advances toward the main air intake tunnel 1, tunnel partitions 11 are constructed in the air intake tunnel 3 and the return air tunnel 4 at predetermined intervals (approximately 50-100 meters) to block the tunnel passage between the goaf and the coal mining face 7. Each ventilation duct 12 or connecting tunnel 6 is located between two tunnel partitions 11. These tunnel partitions 11 can be constructed concrete walls, bag-filled walls, or the like.

[0051] In the direction opposite to the excavation direction of the coal mining face 7, the goaf is divided into a heat dissipation zone 8, an oxidation zone 9, and a suffocation zone 10 according to the oxygen concentration. The oxygen concentration in the heat dissipation zone 8 is greater than 14%, the oxygen concentration in the oxidation zone 9 is between 7-14, and the oxygen concentration in the suffocation zone 10 is less than 7%. The closer to the coal mining face 7, the higher the oxygen concentration; the farther from the coal mining face 7, the lower the oxygen concentration. The heat dissipation zone 8 is adjacent to the coal mining face 7. Although its oxygen content is high, the heat dissipation effect of the heat dissipation zone 8 is good and it will basically not spontaneously combust. The oxygen concentration in the suffocation zone 10 is low and it will basically not spontaneously combust. The oxidation zone 9 is between the heat dissipation zone 8 and the suffocation zone 10 and has a poor heat dissipation effect. If the oxygen concentration in the oxidation zone 9 exceeds 14%, there is a risk of spontaneous combustion.

[0052] In order to reduce or minimize the surface air leakage in the oxidation zone 9, a wind pressure short-circuit method can be adopted, that is, the air pressure in the heat dissipation zone 8 is increased to block the gas in the oxidation zone 9 from flowing into the heat dissipation zone 8, thereby blocking the gas flow path of the heat dissipation zone 8 and the asphyxiation zone 10, which can effectively reduce the surface air leakage in the oxidation zone and the asphyxiation zone.

[0053] Specifically, the valve on the ventilation pipe 12 leading to the heat dissipation zone 8 is opened, while the valves on the remaining ventilation pipes 12 remain closed. Air is supplied to the heat dissipation zone 8 via a local ventilator 14 to increase the pressure until the pressure difference between the heat dissipation zone 8 and the ground is within a preset range. Assuming the surface pressure is P0, the air pressure in the heat dissipation zone 8, P1, = P0 - a. The values of P0 and a can be measured and set based on actual operating conditions. Underground pressure generally does not reach P0, so P1 ≤ P0. After gas is filled into the heat dissipation zone 8, an equal pressure zone is formed in the heat dissipation zone 8 between the front and rear chute partitions 11, and the air pressure in the heat dissipation zone 8 is greater than the air pressure in the oxidation zone 9, so that the gas in the oxidation zone 9 and the asphyxiation zone 10 no longer flows into the heat dissipation zone 8, but is retained in the oxidation zone 9 and the asphyxiation zone 10. The air pressure in the oxidation zone 9 and the asphyxiation zone 10 will also increase, thereby blocking, slowing down or reducing the surface gas from entering the oxidation zone 9 and the asphyxiation zone 10 through surface cracks, which can effectively reduce surface air leakage in the oxidation zone and the asphyxiation zone.

[0054] The method for controlling air leakage in the goaf provided by the present invention not only enhances the heat dissipation effect of the heat dissipation belt 8 but also suppresses air leakage in the oxidation belt 9 and the asphyxiation belt 10 by pressing fresh air into the heat dissipation belt 8, thereby achieving the effect of preventing air leakage in the oxidation belt 9 and the asphyxiation belt 10 by pressing air in the heat dissipation belt 8.

[0055] In one embodiment, an underground air pressure sensor is installed in the heat dissipation belt 8, and a ground air pressure sensor is installed on the ground. The local ventilator 14 is a variable frequency fan.

[0056] The underground air pressure sensor and the ground air pressure sensor are respectively connected to the local ventilator 14 for signal transmission.

[0057] When the pressure difference between the heat dissipation belt 8 and the ground is less than a preset range, the local ventilator 14 increases its rotation speed to increase the air supply volume.

[0058] When the pressure difference between the heat dissipation belt 8 and the ground is greater than a preset range, the local ventilator 14 reduces the rotation speed and the air supply volume.

[0059] In this embodiment, the local ventilator 14 can adjust the rotation speed according to the pressure difference between the ground air pressure sensor and the underground air pressure sensor to change the air supply volume, thereby realizing automatic control and helping to maintain the air pressure in the heat dissipation belt 8 at a relatively stable level.

[0060] The advantage of using variable-frequency local ventilators 14 is that, due to the impact of mining face advancement and continuous subsidence of the overlying rock strata in the goaf, surface air leakage varies greatly and rapidly, and pressure fluctuations in the pressure-equalizing zone are generally more dramatic. Therefore, automatic variable-frequency technology is required to automatically adjust the speed of local ventilators 14 to maintain the pressure difference between the compression heat dissipation zone 8 and the ground within a preset range. The optimal pressure difference between the compression heat dissipation zone 8 and the ground is zero.

[0061] In one embodiment, multiple local ventilators 14 are installed in parallel in the air inlet tunnel 1. When one of the local ventilators 14 fails, it can be replaced by another local ventilator 14. Multiple local ventilators 14 can also be turned on at the same time to increase the air supply.

[0062] In one embodiment, surface cracks in the area corresponding to the oxidation zone 9 are sealed. To further improve the prevention and control of air leakage in the oxidation zone 9, surface cracks above the oxidation zone 9 behind the coal mining face 7 are sealed to reduce air leakage into the oxidation zone 9. Grouting is generally used for sealing.

[0063] In one embodiment, surface cracks are sealed immediately behind the coal mining face 7. In this embodiment, surface cracks are sealed immediately behind the coal mining face 7. Newly formed surface cracks are large and should be sealed promptly to reduce air leakage.

[0064] In one embodiment, the heat dissipation belt 8 has at least two sections of channel partitions 11 along the excavation direction of the coal mining face 7, which improves the effect of blocking gas flow. After the gas is filled, the pressure equalization effect is better.

[0065] In one embodiment, a connecting lane 6 in the heat dissipation zone 8 is adjacent to the oxidation zone 9. Gas is injected into the heat dissipation zone 8 from the junction of the oxidation zone 9 and the heat dissipation zone 8. After the gas pressure reaches a preset value, the local ventilator 14 remains on, so that the gas pressure near the oxidation zone 9 is slightly higher, which can better prevent the gas in the oxidation zone 9 from entering the heat dissipation zone 8.

[0066] In one embodiment, the space of the heat dissipation belt 8 near the coal mining face 7 is filled or forcibly caving to block the return air corner.

[0067] Since the air leakage in the goaf basically flows from the return air corner of the working face to the return air chute 4, in order to further improve the air leakage prevention effect, the space of the heat dissipation belt 8 near the coal mining working face 7 is filled or forced to be topped off to block the return air corner.

[0068] In one embodiment, a working face ventilator 15 is installed in the air inlet tunnel 1, and air is supplied to the air inlet chute 3 through the working face ventilator 15 to increase the air pressure in the coal mining working face 7, so that the air pressure in the entire coal mining working face 7 is increased, and the air flow in the oxidation zone 9 is blocked in combination with the equalizing pressure zone of the heat dissipation zone 8, which can achieve a better effect in preventing air leakage.

[0069] In one embodiment, an adjusting window 16 is installed in the return air chute 4. When the working face ventilator 15 is used to increase the pressure, the opening of the adjusting window 16 can be reduced to help quickly increase the air pressure in the coal mining working face 7.

[0070] Example 1: The fully mechanized mining face of a mine is a shallow coal seam with a surface air leakage of about 200m 3 / min. After adopting conventional surface plugging measures and goaf grouting measures, the surface air leakage was reduced to 100m 3 / min, but the oxygen concentration in the goaf changes little, and the oxygen concentration in the return air corner also has no obvious change.

[0071] The problem of low oxygen in the return air corner caused by air leakage is quite serious, with the lowest value being about 16%.

[0072] Air leakage also causes poor inerting effect in the goaf, resulting in unclear division of the "three zones" of heat dissipation zone, warming zone and asphyxiation zone, and posing a serious risk of spontaneous combustion.

[0073] Analysis shows that surface plugging only significantly reduces air leakage in the heat dissipation zone 8, but has little effect on reducing leakage in the oxidation zone 9 and the asphyxiation zone 10. Because surface plugging reduces air leakage in the heat dissipation zone 8, it increases the pressure difference between the oxidation zone 9 and the asphyxiation zone 10, which helps reduce air leakage.

[0074] Implementation plan: Construct a drift partition 11. Taking the coal mining face 7 of a nearby mine as a reference and starting from the coal mining face 7, for example, the heat dissipation zone 8 is approximately 100m long, the oxidation zone 9 is also approximately 100m long, and the goaf area approximately 200m beyond the coal mining face 7 is the suffocation zone 10. Therefore, a drift partition 11 is constructed every 50m to 100m of advancement of the working face.

[0075] The first surface plugging was carried out at the delayed coal mining face 7, and the second surface plugging was carried out after the delayed coal mining face 7100m. The depth of the second plugging was increased from 0.5m to 1m.

[0076] The local ventilator 14 is used to ventilate the heat dissipation zone 8 under equal pressure. When the air supply volume reaches 50m 3 / min, the pressure in the pressure equalization zone of the heat dissipation belt 8 rises by 500Pa.

[0077] One week after taking the above measures, the oxygen concentration in the oxidation zone 9 dropped to below 10%, the oxygen concentration in the asphyxiation zone 10 dropped to about 5%, the oxygen concentration in the heat dissipation zone 8 rose to more than 18%, and the oxygen concentration in the return air corner recovered to about 20%. The surface air leakage in the goaf was effectively controlled.

[0078] As needed, the above technical solutions can be combined to achieve the best technical effect.

[0079] The above description is only the principle and preferred embodiment of the present invention. It should be noted that for those skilled in the art, several other variations can be made based on the principle of the present invention, which should also be considered as the scope of protection of the present invention.

Claims

1. A method for controlling air leakage in goaf, characterized in that: The steps include: S01: excavating an auxiliary tunnel outside the return air chute in advance, and excavating a plurality of spaced connecting tunnels between the auxiliary tunnel and the return air chute; A ventilation pipe is pre-buried in each of the connecting tunnels, and a valve is installed on the ventilation pipe; A main air supply pipe is installed in the auxiliary lane, and the main air supply pipe is connected to each of the ventilation pipes; S02: Install a local ventilator in the main air inlet lane, and connect the air inlet end of the main air supply pipe to the local ventilator; S03: As the coal mining face advances toward the air intake tunnel, tunnel partitions are constructed in the air intake tunnel and the return air tunnel at preset intervals, and each ventilation pipe is located between the two preceding and following tunnel partitions; In a direction opposite to the excavation direction of the coal mining working face, the goaf is divided into a heat dissipation zone, an oxidation zone and a suffocation zone according to the oxygen concentration; S04: opening the valve on the ventilation pipe leading to the heat dissipation belt, and keeping the valves on the other ventilation pipes closed; Supplying air to the heat dissipation belt through the local ventilator to increase the pressure until the pressure difference between the heat dissipation belt and the ground is within a preset range; The air pressure in the heat dissipation zone is greater than the air pressure in the oxidation zone.

2. The method for controlling air leakage in goaf according to claim 1, characterized in that: An underground air pressure sensor is installed in the heat dissipation belt, and a ground air pressure sensor is installed on the ground; The local ventilator is a variable frequency fan; The underground air pressure sensor and the surface air pressure sensor are respectively connected to the local ventilator signal; When the pressure difference between the heat dissipation belt and the ground is less than a preset range, the local ventilator increases its speed to increase the air supply volume; When the pressure difference between the heat dissipation belt and the ground is greater than a preset range, the local ventilator reduces its rotation speed and the air supply volume.

3. The method for controlling air leakage in goaf according to claim 1, characterized in that: A plurality of local ventilators arranged in parallel are installed in the main air inlet tunnel.

4. The method for controlling air leakage in goaf according to claim 1, characterized in that: The surface fissures in the area corresponding to the oxidation zone are sealed.

5. The method for controlling air leakage in goaf according to claim 1, characterized in that: Surface fissures are sealed immediately behind the coal mining face on the surface.

6. The method for controlling air leakage in goaf according to claim 1, characterized in that: In the excavation direction along the coal mining working face, the heat dissipation zone has at least two sections of longitudinal slot partitions.

7. The method for controlling air leakage in goaf according to claim 1, characterized in that: One of the connecting lanes in the heat dissipation zone is adjacent to the oxidation zone.

8. The method for controlling air leakage in goaf according to claim 1, characterized in that: The space of the heat dissipation belt close to the coal mining working face is filled or forcibly topped out to block the return air corner.

9. The method for controlling air leakage in goaf according to claim 1, characterized in that: A working face ventilator is installed in the air inlet tunnel, and air is supplied to the air inlet chute through the working face ventilator to increase the air pressure in the coal mining working face.

10. The method for controlling air leakage in goaf according to claim 9, characterized in that: An adjusting window is installed in the return air chute.

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