Gas control method for goaf areas adjacent to coal seams in high-gas coal mines

Abstract

The present invention belongs to the field of coal mine safety technology and provides a method for gas control in goafs adjacent to coal seams in high-gas coal mines. The method comprises the following steps: arranging a basic ventilation circuit; arranging a high-extraction laneway; arranging extraction drill sites and extraction boreholes; and arranging extraction pipelines. Before mining, gas is pre-extracted from the adjacent coal seams via high-negative pressure extraction pipelines. During mining, the bottoms of the extraction boreholes are cut off, thereby connecting them to the goaf, and the extraction boreholes extract gas from the goaf via low-negative pressure extraction pipelines. As the mining face gradually advances, the sealed outer walls of the high-extraction laneway, the extraction drill sites, and the high-negative pressure and low-negative pressure extraction pipelines therein are gradually removed. The high-extraction laneway and extraction boreholes simultaneously extract gas from the goaf. The present invention flexibly configures extraction modes based on the mining mode, solving the problem of excessive gas in the upper corner and return air chute, which cannot be addressed with a single high-extraction laneway. This improves gas extraction efficiency and ensures safe production at the mining face.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mine safety, and relates to a gas control method suitable for goaf areas adjacent to coal seams in high-gas coal mines. Background Art

[0002] Coal mine gas (CMG), a harmful and potentially dangerous gas produced during coal mining operations, primarily composed of methane, poses a significant threat to coal mine safety. Methane exists in coal in various forms, primarily free and adsorbed. Research data shows that approximately 90% of methane is deeply embedded in the coal mass in an adsorbed state, while only approximately 10% exists in a free state. This unique form of methane makes its control particularly complex and challenging.

[0003] Among the many hazards associated with coal mining, gas inrush from goafs is undoubtedly the most serious. It not only poses a serious threat to coal mine safety but can also easily lead to excessive gas levels in the upper corners, potentially causing equipment shutdowns at the working face and immeasurable losses to coal mine production. Gas control is particularly challenging in deep coal seams in my country, particularly due to the unique geological conditions of high ground stress, high gas pressure, and low permeability.

[0004] To effectively prevent and control gas outburst hazards in coal mine goafs, the industry has explored a variety of methods. Among them, methods such as pipe extraction, inclined drilling, roof strike drilling, high-level extraction lanes, using holes instead of lanes, and large-diameter drilling in adjacent lanes each have their own unique characteristics, but they also have their own limitations.

[0005] Intubation is a relatively simple method for extracting gas from goafs. This involves laying a gas extraction pipeline on the return airway of the mining face, connecting one end to a low-pressure extraction system, and placing the other end inside the goaf for open extraction. This method offers simple processes and operational management, but the extraction concentration is relatively low, making it suitable only for situations where gas outbursts from the goaf are not severe.

[0006] Dip drilling is a method of extracting gas from goafs by drilling holes in the return air chute of the mining face, close to the mining face, at the lower boundary of the goaf's fracture zone. This method offers the advantages of simple construction and operation management, as it eliminates the need for drilling sites. However, the effective duration and distance of each extraction borehole are short, resulting in generally poor extraction results. Furthermore, the engineering effort is greater than that of drilling holes along the roof.

[0007] The roof-direction drilling method involves excavating a drill site within the return air channel of the mining face. Drainage is then performed by drilling holes parallel to the coal seam roof on the side of the drill site near the cut hole. This method offers the advantages of higher extraction concentration, less drilling effort than with inclination drilling, and continuous extraction. However, the drilling site is large, complex to manage, and has limited extraction capacity. When the goaf of the working face reaches a certain level, this method cannot resolve the problem of exceeding the upper corner limit.

[0008] The high-extraction lane method is similar in principle to roof-directed drilling, but uses laneways instead of boreholes, significantly increasing extraction rates. However, this method requires significant investment and is only suitable for situations where gas outflow from the goaf is significant and cannot be addressed through roof-directed drilling.

[0009] The hole-in-place-drift method uses larger-diameter directional boreholes instead of high-extraction drifts. The advantage of this method is that the number of drilling sites is significantly reduced, and the extraction volume is greater than that of roof strike drilling. However, the drilling efficiency is lower than that of conventional drilling, and the investment is between roof strike drilling and high-extraction drifts, so the investment is still relatively high.

[0010] The adjacent tunnel large-diameter drilling method involves drilling large-diameter holes in the adjacent working face directly into the goaf of the current working face for extraction. This method offers the advantage of higher extraction concentrations than cannulated gas extraction, but it also involves complex construction, the risk of hole collapse, and the even more complex casing installation process, resulting in high investment and uneconomical operation.

[0011] In summary, while all the aforementioned treatment methods have their own unique advantages, they all have shortcomings under specific conditions. This is particularly true when faced with complex situations where the adjacent coal seam is 9 meters from the mined layer, the mined layer is 3 meters thick, the adjacent coal seam is 1 meter thick, and the gas content is high. Even the highly effective high-pressure extraction method cannot completely prevent excessive gas levels in the upper corners and return air lanes. Therefore, a new solution is urgently needed to overcome the shortcomings of existing technologies and ensure the continued safety and stability of coal mine production. Summary of the Invention

[0012] In view of this, the purpose of the present invention is to provide a method for gas control in the goaf area adjacent to the coal seams in high-gas coal mines, so as to significantly improve the pre-extraction rate of the adjacent coal seams, ensure that the amount of gas gushing from the adjacent coal seams into the goaf during the mining of the comprehensive mining working face is controllable, and significantly increase the gas extraction volume in the goaf, thereby improving the safety of mine production.

[0013] To achieve the above object, the present invention provides a method for controlling gas in goaf areas adjacent to coal seams in high-gas coal mines, comprising the following steps:

[0014] Arrange basic ventilation circuit: excavate to form a fully mechanized mining face, excavate centralized return air lane, centralized main transport lane and centralized auxiliary transport lane in the rock layer below the coal seam, and further excavate air inlet chute and return air chute connected to the cut hole of the fully mechanized mining face;

[0015] Arrangement of high extraction roadway: Arrange high extraction roadway under the floor of the adjacent coal seam in the form of return air chute parallel to the mining face, and the roof of the high extraction roadway is higher than the roof of the adjacent coal seam;

[0016] Arrangement of extraction drill sites and extraction boreholes: Arrange at least two extraction drill sites in the coal wall on the side of the high extraction roadway facing the air inlet chute, and use the directional drilling method of "fan-shaped opening holes and parallel end holes" to open multiple extraction boreholes in the extraction drill sites towards the cut holes of the fully mechanized mining face;

[0017] Arrange the extraction pipeline: Arrange high-negative pressure extraction pipeline and low-negative pressure extraction pipeline in the high extraction lane, and connect the high-negative pressure extraction pipeline with each extraction borehole;

[0018] Configure the extraction mode: Before mining, each extraction borehole pre-extracts gas from the adjacent coal seam through a high-vacuum extraction pipeline; during mining, the bottom of the extraction borehole is cut off and connected to the goaf, and the high-vacuum extraction pipeline and the low-vacuum extraction pipeline simultaneously extract gas from the goaf.

[0019] Optionally, the extraction mode configuration also includes: as the mining face gradually advances, the enclosed outer walls of the high-extraction lanes and each extraction drilling site are gradually dismantled, and the high-negative pressure extraction pipelines and low-negative pressure extraction pipelines in each extraction drilling site are gradually dismantled, and the high-extraction lanes and extraction boreholes simultaneously extract gas from the goaf.

[0020] Optionally, when arranging the extraction boreholes, the extraction boreholes include a main borehole and sub-boreholes formed by branches of the main borehole, and each main borehole branches into at most 2 sub-boreholes.

[0021] Optionally, when arranging the extraction drilling holes, each extraction drilling site shall open a total of 15 extraction drilling holes with a hole diameter of 96 mm, and the final hole spacing between two adjacent extraction drilling holes shall be 10 m.

[0022] Optionally, when arranging the extraction boreholes, the horizontal projection of the extraction borehole closest to the high extraction laneway is 10m away from the high extraction laneway.

[0023] Optionally, when arranging the extraction drilling sites, at least two extraction drilling sites are arranged at intervals of 300m in the coal wall on the side of the high extraction tunnel facing the air inlet chute, and the arrangement order of the extraction drilling sites is: arranged in sequence along the direction from the stop mining line to the cutting eye.

[0024] Optionally, when arranging the extraction drilling site, the first extraction drilling site and the second extraction drilling site are arranged in the coal wall on the side of the high extraction tunnel facing the air inlet chute, and the height of the first extraction drilling site and the second extraction drilling site are 2.6m, the width is 3.5m, and the depth is 5m.

[0025] Optionally, the thickness of the current coal seam is 3m, the thickness of the adjacent coal seam is 1m, and the distance between the two is 9m.

[0026] Optionally, when arranging the high-extraction tunnel, the projection of the high-extraction tunnel on the horizontal plane is 35m away from the return air chute, and the height of the high-extraction tunnel is 2.6m and the width is 3m.

[0027] Optionally, when arranging the high-extraction tunnel, the closed position of the high-extraction tunnel is located between the extraction drilling site and the cutting eye, and the distance between the closed outer wall and the extraction drilling site is 10m.

[0028] The beneficial effects of the present invention are:

[0029] The goaf gas control method disclosed in the present invention provides a new solution for low-permeability coal seams and adjacent coal seams in high-gas coal mines. Its beneficial effects are significant, specifically reflected in the following aspects:

[0030] First, by arranging a basic ventilation circuit and high-level extraction laneways, with the roof of the high-level extraction lanes elevated above the roof of the adjacent coal seams, the extraction boreholes were distributed throughout the coal seam and adjacent seams. This physically established effective gas extraction channels for the goaf of the coal seam and adjacent seams. This layout not only facilitated subsequent gas extraction but also ensured efficient extraction.

[0031] Secondly, the present invention adopts a directional drilling method with "fan-shaped openings and parallel end holes". Extraction drilling sites are arranged at intervals in the coal wall on the side of the high extraction lane facing the air inlet chute, and multiple extraction boreholes are opened. This drilling arrangement can maximize coverage of gas accumulation areas and improve the efficiency and accuracy of gas extraction. At the same time, by arranging high-negative pressure extraction pipelines and low-negative pressure extraction pipelines, the present invention realizes the function of flexibly configuring the extraction mode according to the mining mode, further improving the effect of gas control.

[0032] Before mining, each extraction borehole pre-extracts gas from adjacent layers through a high-negative-pressure extraction pipeline, effectively reducing the gas content in these layers. This step is crucial for preventing gas overruns during mining. During mining, the bottom of the extraction borehole is cut off, connecting it to the goaf. This function shifts from a single pre-extraction function to a dual one: pre-extracting gas from adjacent layers and the goaf. This solves the problem of gas overruns in the upper corners and return air chute, which cannot be addressed with a single high-pressure extraction lane. This shift not only improves gas extraction efficiency but also ensures safe production at the mining face.

[0033] Furthermore, this invention achieves precise control over the gas extraction process by optimizing borehole layout and extraction pipeline configuration. The boreholes consist of a main borehole and sub-bores branching off from the main borehole. Each main borehole branches into a maximum of two sub-bores. This design ensures comprehensive extraction coverage while avoiding resource waste. Furthermore, parameters such as borehole diameter, the spacing between adjacent boreholes, and the distance between the high-pressure extraction lane and the return air chute have all been carefully designed to ensure optimal gas extraction results.

[0034] In summary, the goaf gas control method disclosed in this invention effectively controls gas in goafs adjacent to gassy coal mines by comprehensively utilizing basic ventilation circuits, high-extraction lanes, directional drilling, and a flexible extraction model. This method not only improves the efficiency and accuracy of gas extraction but also ensures safe production at the mining face, resulting in significant indirect economic and social benefits. For mines with adjacent layers that are too thick and contain high gas contents to be mined, this invention provides a new and effective solution.

[0035] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0037] Figure 1 A top view of the implementation process of the method for controlling gas in goafs adjacent to coal seams in high-gas coal mines provided by the present invention;

[0038] Figure 2 A side view of the implementation process of the method for controlling gas in goafs adjacent to coal seams in high-gas coal mines provided by the present invention;

[0039] Figure 3 The present invention provides a flow chart of a method for controlling gas in goaf areas adjacent to coal seams in high-gas coal mines.

[0040] Reference numerals:

[0041] 100-centralized main transport tunnel; 200-centralized auxiliary transport tunnel; 300-centralized return air tunnel; 400-inlet air chute; 500-return air chute; 600-high-extraction tunnel; 610-extraction drilling site; 611-first extraction drilling site; 612-second extraction drilling site; 620-extraction drilling hole; 630-high-negative-pressure extraction pipeline; 640-low-negative-pressure extraction pipeline; 700-cutting eye; 800-main coal seam; 900-adjacent coal seam. DETAILED DESCRIPTION

[0042] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0043] Among them, the accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0044] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0045] See also Figures 1 to 3 In order to significantly improve the pre-extraction rate of the adjacent coal seam 900, ensure that the amount of gas gushing from the adjacent coal seam 900 into the goaf during the fully-mechanized mining face is controllable, significantly increase the gas extraction volume in the goaf, and improve the safety of mine production, the present invention provides a gas control method for the goaf adjacent to the coal seam 900 in a high-gas coal mine. The control method includes the following steps:

[0046] Step S100, arranging the basic ventilation circuit: excavating to form a fully mechanized mining face, excavating a centralized return air lane 300, a centralized main transport lane 100, and a centralized auxiliary transport lane 200 in the rock layer below the coal seam 800, and further excavating an air intake chute 400 and a return air chute 500 connected to the cut hole 700 of the fully mechanized mining face;

[0047] Step S200, arranging a high-extraction tunnel 600: Arranging the high-extraction tunnel 600 below the floor of the adjacent coal seam 900 in a manner parallel to the return air chute 500 of the mining face, with the roof of the high-extraction tunnel 600 being higher than the roof of the adjacent coal seam 900;

[0048] Step S300, arranging the extraction drilling site 610 and the extraction borehole 620;

[0049] Step S400, arranging the extraction pipeline: arranging a high-negative-pressure extraction pipeline 630 and a low-negative-pressure extraction pipeline 640 in the high-extraction lane 600, wherein the high-negative-pressure extraction pipeline 630 is connected to each extraction borehole 620;

[0050] Step S500: Configure the sampling mode.

[0051] Step S300 also includes:

[0052] Step S310: Arrange at least two extraction drill sites 610 in the coal wall of the high extraction tunnel 600 facing the air inlet chute 400;

[0053] Step S320: using a directional drilling method of "fan-shaped opening and parallel end holes" to open multiple extraction boreholes 620 in the extraction drilling site 610 toward the cut hole 700 of the fully mechanized mining face;

[0054] Step S500 further includes:

[0055] Step S510: Before mining, each extraction borehole 620 pre-extracts gas from the adjacent coal seam 900 through the high-negative-pressure extraction pipeline 630;

[0056] Step S520: During mining, the bottom of the extraction borehole 620 is cut off and connected to the goaf, and the high-negative-pressure extraction pipeline 630 and the low-negative-pressure extraction pipeline 640 simultaneously extract gas from the goaf.

[0057] Step S530: As the mining face gradually advances, the enclosed outer walls of the high-extraction tunnel 600 and each extraction drilling site 610 are gradually dismantled, and the high-negative pressure extraction pipeline 630 and the low-negative pressure extraction pipeline 640 in each extraction drilling site 610 are gradually dismantled. The high-extraction tunnel 600 and the extraction borehole 620 simultaneously extract gas from the goaf through the high-negative pressure extraction pipeline 630 and the low-negative pressure extraction pipeline 640.

[0058] In some optional embodiments, in step S310, at least two extraction drill sites 610 are arranged at intervals of 300 m in the coal wall on the side of the high extraction tunnel 600 facing the air inlet chute 400, and the arrangement order of the extraction drill sites 610 is: arranged in sequence along the direction from the stop mining line to the cutting eye 700.

[0059] In some optional embodiments, in step S310, when arranging the extraction drilling site 610, a first extraction drilling site 611 and a second extraction drilling site 612 are arranged in the coal wall on the side of the high extraction tunnel 600 facing the air inlet chute 400, and the height of the first extraction drilling site 611 and the second extraction drilling site 612 are 2.6m, 3.5m, and 5m respectively.

[0060] In some optional embodiments, in step S320, the drainage borehole 620 includes a main borehole and sub-boreholes formed by branches from the main borehole. Each main borehole branches into a maximum of two sub-boreholes. Each drainage drilling site 610 has a total of 15 drainage boreholes 620 with a diameter of 96 mm. The horizontal projection of the borehole closest to the high-pressure drainage lane 600 is 10 meters away from the high-pressure drainage lane 600, and the final distance between two adjacent drainage boreholes 620 is 10 meters.

[0061] In some optional embodiments, the thickness of the current coal seam 800 is 3 meters, the thickness of the adjacent coal seam 900 is 1 meter, and the distance between the two is 9 meters. In step S200, when high-pressure extraction tunnel 600 is arranged, the horizontal projection of high-pressure extraction tunnel 600 is 35 meters away from the return air chute 500. The height of high-pressure extraction tunnel 600 is 2.6 meters, and the width is 3 meters. When high-pressure extraction tunnel 600 is arranged, the sealed position of high-pressure extraction tunnel 600 is located between the extraction drilling site 610 and the cut hole 700, and the distance between the sealed outer wall and the extraction drilling site 610 is 10 meters.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for controlling gas in goafs adjacent to coal seams in high-gas coal mines, characterized by: The following steps are involved: Arrangement of basic ventilation circuit: excavation to form a fully mechanized mining face, excavation of a centralized return air lane (300), a centralized main transport lane (100) and a centralized auxiliary transport lane (200) in the rock layer below the coal seam (800), and further excavation of an air inlet chute (400) and a return air chute (500) connected to the cut hole (700) of the fully mechanized mining face; Arrange a high extraction lane: Arrange a high extraction lane (600) along the bottom plate of the adjacent coal seam (900), and the top plate of the high extraction lane (600) is higher than the top plate of the adjacent coal seam (900); Arrange the extraction drilling site and extraction boreholes: arrange at least two extraction drilling sites (610) in the coal wall on the side of the high extraction roadway (600) facing the air inlet chute (400), and use the directional drilling method of "opening holes in a fan shape and ending holes in parallel" to open multiple extraction boreholes (620) in the extraction drilling site (610) toward the cut hole (700) of the fully mechanized mining face; Arrange the extraction pipeline: Arrange a high-negative-pressure extraction pipeline (630) and a low-negative-pressure extraction pipeline (640) in the high extraction lane (600), and the high-negative-pressure extraction pipeline (630) is connected to each extraction borehole (620); The extraction mode is configured as follows: before mining, each extraction borehole (620) pre-extracts gas from the adjacent coal seam (900) through the high-negative pressure extraction pipeline (630); during mining, the bottom of the extraction borehole (620) is cut off and connected to the goaf, and the high-negative pressure extraction pipeline (630) and the low-negative pressure extraction pipeline (640) simultaneously extract gas from the goaf.

2. The method for controlling gas in goaf according to claim 1, characterized in that: The configured extraction mode also includes: as the mining face gradually advances, the sealed outer wall of the high extraction lane (600) and each extraction drilling site (610) are gradually dismantled, and the high negative pressure extraction pipeline (630) and the low negative pressure extraction pipeline (640) in each extraction drilling site (610) are gradually dismantled, and the high extraction lane (600) and the extraction drill hole (620) simultaneously extract gas from the goaf.

3. The method for controlling gas in goaf according to claim 1, characterized in that: When arranging the extraction boreholes (620), the extraction boreholes (620) include a main borehole and sub-boreholes formed by branches of the main borehole, and each main borehole branches into at most two sub-boreholes.

4. The method for controlling gas in goaf according to claim 1 or 3, characterized in that: When arranging the extraction boreholes (620), each extraction drilling site (610) has 15 extraction boreholes (620) with a hole diameter of 96 mm, and the final hole spacing between two adjacent extraction boreholes (620) is 10 m.

5. The method for controlling gas in goaf according to claim 1 or 3, characterized in that: When arranging the extraction boreholes (620), the horizontal projection of the extraction borehole (620) closest to the high extraction lane (600) is 10m away from the high extraction lane (600).

6. The method for controlling gas in goaf according to claim 1, characterized in that: When arranging the extraction drill sites (610), at least two extraction drill sites (610) are arranged at intervals of 300 m in the coal wall on the side of the high extraction roadway (600) facing the air inlet chute (400). The arrangement order of the extraction drill sites (610) is: arranged in sequence along the direction from the stop mining line to the cutting eye (700).

7. The method for controlling gas in goaf according to claim 1 or 6, characterized in that: When arranging the extraction drill site (610), a first extraction drill site (611) and a second extraction drill site (612) are arranged in the coal wall on the side of the high extraction roadway (600) facing the air inlet chute (400), and the height of the first extraction drill site (611) and the second extraction drill site (612) are 2.6m, the width is 3.5m, and the depth is 5m.

8. The method for controlling gas in goaf according to claim 1, characterized in that: The thickness of the present coal seam (800) is 3m, the thickness of the adjacent coal seam (900) is 1m, and the distance between the two is 9m.

9. The method for controlling gas in goaf according to claim 8, characterized in that: When the high extraction tunnel (600) is arranged, the projection of the high extraction tunnel (600) on the horizontal plane is 35m away from the return air chute (500), and the height of the high extraction tunnel (600) is 2.6m and the width is 3m.

10. The method for controlling gas in goaf according to claim 1, characterized in that: When arranging the high extraction tunnel (600), the sealed position of the high extraction tunnel (600) is located between the extraction drilling site (610) and the cut hole (700), and the distance between the sealed outer wall and the extraction drilling site (610) is 10m.

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