A method for preventing gas overrun in initial mining of an ultra-thick coal seam fully-mechanized caving face

Abstract

The application discloses a kind of prevention and cure method of gas over-limit of ultra-thick coal seam fully mechanized caving face initial mining, when roadway layout in ultra-thick coal seam planning, a main air inlet lane, a main air return lane and panel drainage lane are constructed in mining area boundary;The production process before the first weighting of roof is the initial mining of working face;Before working face mining, drill site is constructed in the lane adjacent to the lane on both sides of working face, and directional interception extraction is carried out in the drill site to the pre-caving top coal body above the mining height of fully mechanized caving face;Before working face mining or during working face formation, bedding borehole is constructed in advance in drainage lane, and the borehole is constructed at the top of the roadway wall of drainage lane, to ensure that the final hole of borehole is located in different height range of working face not collapsed solid coal;To prevent gas over-limit in upper corner of working face, short borehole is constructed in the coal body not collapsed upward in the lane on one side of working face air return lane, and the borehole faces the advancing direction of working face mining, to realize interception extraction before coal body collapse.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coal mining, more particularly, relates to a prevention and control method for preventing gas overrun during initial mining of fully mechanized caving face of super-thick coal seam. BACKGROUND

[0002] For high-gas mines or coal and gas outburst mines with large thickness of coal seam, before fully mechanized mining, gas extraction from the whole thickness of the coal seam is needed, that is, drilling needs to extract the whole thickness of the coal seam to reach the standard before mining operation. The gas extraction technology for thick coal seam mainly adopts in-seam drilling extraction, floor roadway through-seam drilling extraction, ground well gas extraction, and a combination of multiple measures, which has great advantages in eliminating the outburst danger of the coal seam and reducing the gas content in the coal seam. The main difference between different measures is the time of extraction reaching the standard and the amount of drilling construction. For fully mechanized faces that have reached the extraction standard and have production conditions, gas accidents are most likely to occur during the initial mining stage of the working face.

[0003] During the initial mining period, the coal seam roof has not yet collapsed, and the roof overburden above the main mining coal seam is in a cantilever beam stress state. Only when the weight of the upper overburden is greater than the adhesion of the coal seam roof, the roof overburden will tilt and collapse downward to the gob area in a short time. In order to prevent gas overrun accidents caused by large air leakage, large-scale roof collapse causing instantaneous gas emission, and other factors during the initial mining period of the fully mechanized face, the common method is to increase the air volume of the working face, use pre-splitting blasting, and other measures to strengthen management, which has certain effect on relieving the gas overrun of the initial mining of the working face or preventing gas accidents. This measure has been maturely applied in coal-producing areas. However, for super-thick coal-producing areas with a mining coal seam thickness of 20-50m or even more than 50m, simply increasing the air volume of the fully mechanized face and blasting to release the roof cannot solve the gas problem of the fully mechanized face of super-thick coal seam. Therefore, for super-thick coal seams with a mining coal seam thickness of more than 20m in China, a prevention and control method for preventing gas overrun during initial mining of fully mechanized caving face is proposed. SUMMARY

[0004] In view of the problems existing in the prior art, the present application provides a prevention and control method for preventing gas overrun during initial mining of fully mechanized caving face of super-thick coal seam. Based on the traditional method of increasing air volume and blasting to release the roof before initial mining of the fully mechanized face, a variety of new gas extraction methods are used to intercept and extract the gas in the upper part of the exposed coal body of the fully mechanized face, so as to realize timely extraction of the gas in the coal body when the stress unloading cracks appear in the coal body, and avoid the occurrence of gas overrun accidents caused by the instantaneous release of a large amount of gas caused by the collapse of a large amount of top coal.

[0005] To achieve the above object, the present application adopts the following technical solutions.

[0006] The application provides a prevention and treatment method for gas over-limit in initial mining of fully-mechanized caving face of super-thick coal seam, which comprises the following steps:

[0007] a. When planning the roadway layout of the super-thick coal seam, a main air inlet roadway, a main air return roadway and a panel drainage roadway are constructed at the boundary of the mining area, so that the main fully-mechanized caving face in the panel can achieve independent ventilation and realize U-type ventilation;

[0008] b. The interval between the start of the fully-mechanized caving face and the first roof caving of the fully-mechanized caving face is called the first roof weighting, and the production process before the first roof weighting is the initial mining of the fully-mechanized caving face; in addition to the conventional measures such as increasing air volume and pre-splitting blasting roof in the initial mining stage of the fully-mechanized caving face, various gas extraction measures are also used to intercept the gas in the top coal body of the coal seam mining height;

[0009] c. Before the fully-mechanized caving face is mined, a drilling field is constructed in the roadway adjacent to the two sides of the fully-mechanized caving face, and the directional interception and extraction of the pre-roof coal body above the mining height of the fully-mechanized caving face is carried out in the drilling field;

[0010] d. Before the fully-mechanized caving face is mined or during the formation of the fully-mechanized caving face, a bedding hole is constructed in the drainage roadway in advance, the drilling hole is constructed at the top of the roadway wall of the drainage roadway, and the terminal hole of the drilling hole is located in different height ranges of the solid coal which has not collapsed in the fully-mechanized caving face;

[0011] e. In order to prevent the gas in the upper corner of the fully-mechanized caving face from exceeding the limit, a short drilling hole is constructed in the coal body above the fully-mechanized caving face in the roadway on one side of the air return roadway of the fully-mechanized caving face, the drilling hole faces the advancing direction of the fully-mechanized caving face, and the interception and extraction of the coal body before the collapse is realized.

[0012] Further, in step a, the main air inlet roadway at the boundary of the panel is connected with the air inlet main roadway, the main air return roadway at the boundary of the panel is connected with the air return main roadway, and the panel air inlet roadway and the mining area air return roadway are connected by the panel drainage roadway, so as to realize full air pressure ventilation.

[0013] Further, the panel air return roadway is arranged at the boundary of the mining face, so that when a large amount of gas is emitted during the coal production of the mining face, the air return of the mining face can be properly distributed, that is, part of the air return of the mining face flows out through the mining face air return roadway, and part of the air return of the mining face flows out through the roadway between the mining face air return roadway and the panel drainage roadway, so as to realize the diversion of the air return gas of the mining face.

[0014] Further, in step b, the conventional measure of increasing air volume in the initial mining stage is that, based on the normal production period ventilation air volume designed according to the working procedure of the fully-mechanized caving face, the air supply of the fully-mechanized caving face in the initial mining stage is 1.2-1.5 times of the designed air volume.

[0015] Further, in step b, the pre-splitting blasting roof caving is to drill holes in the pre-roof caving coal body or the upper roof rock layer and blast before the fully-mechanized caving face starts to mine.

[0016] Further, in step c, the drill field is constructed between the two adjacent roadways of the working face, and multiple rows of directional long boreholes are constructed in the drill field to achieve the full coverage of the boreholes to the uncaved coal body of the working face.

[0017] Further, the drill field is opened in the roadway adjacent to the fully-mechanized caving face, the drill field is arranged at an angle with the roadway, and the drill field is arranged towards the retreat direction of the working face; the directional boreholes constructed in the roadways on both sides of the fully-mechanized caving face are arranged at an angle, and there is a spatial overlap and intersection in the uncaved coal body above the mining height, which can achieve the stress release of the top coal body due to the mining pressure relief, and the gas release in the coal body is extracted and discharged by the boreholes.

[0018] Further, in step d, the drainage roadway is formed before the roadway construction of the working face, and the coal body above the mining height of the working face is extracted and discharged before the roof caving during the initial mining of the fully-mechanized caving face.

[0019] Further, the boreholes are arranged along the length range of the inclination of the open-off cut of the working face, the boreholes are constructed in two rows or three rows, and are arranged in three flower holes or five flower holes, the terminal holes of the boreholes in the lower row of the roadway are located at the highest horizon, the terminal holes of the uppermost row of boreholes in the upper part of the roadway are located at the lowest horizon, and the boreholes at different horizons are arranged staggeredly.

[0020] Further, in step e, the short boreholes on one side of the air return roadway are constructed during the initial mining stage, and the length of the boreholes is determined according to the thickness of the uncaved coal body above the mining height; the boreholes are constructed towards the solid coal above the top of the air return roadway, the boreholes are obliquely arranged above the solid coal, and the terminal holes of the boreholes enter the rock mass above the coal seam.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] On the basis of increasing the air volume and blasting the roof before the initial mining of the conventional fully-mechanized caving face, the present application adopts multiple new gas extraction methods to intercept and extract the gas in the uncaved coal body above the fully-mechanized caving face, to achieve the timely extraction of the gas in the coal body when the stress unloading cracks appear, to avoid the gas overrun accidents caused by the instantaneous release of a large amount of gas caused by the collapse of a large amount of roof caving coal. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The present application is a plan view of the roadway layout of the super-thick fully-mechanized caving face.

[0024] Figure 2The drawing shows a directional drilling field layout and drilling trajectory plan view of the two sides of the fully mechanized caving face of the present application.

[0025] Figure 3 The drawing shows a bedding drilling plan view of different layers of the drainage roadway construction of the present application.

[0026] Figure 4 The drawing shows a bedding drilling profile of the drainage roadway of the present application.

[0027] Figure 5 The drawing shows a bedding drilling plan view of one side of the working face return air roadway of the present application. DETAILED DESCRIPTION

[0028] The embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the accompanying drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0029] Combination Figures 1 to 5 The embodiment of the present application provides a prevention and control method for gas overrun in initial mining of fully mechanized caving face of super-thick coal seam, which comprises the following steps:

[0030] a. When planning the roadway layout of super-thick coal seam, a main air inlet roadway, a main return air roadway and a panel drainage roadway need to be constructed at the boundary of the mining area, so that the main fully mechanized caving face in the panel can achieve independent ventilation and realize U-type ventilation, avoid the problem of ventilation in the goaf, and prevent gas overrun in the return air roadway of the working face.

[0031] The main air inlet roadway at the boundary of the panel is connected with the air inlet main roadway, the main return air roadway at the boundary of the panel is connected with the return air main roadway, and the panel air inlet roadway and the mining area return air roadway are connected by the panel drainage roadway, thereby realizing full air pressure ventilation.

[0032] The purpose of arranging the panel return air roadway at the boundary of the mining face is to achieve appropriate distribution of return air volume when a large amount of gas is emitted during coal production of the mining face, that is, part of the return air of the mining face flows out through the mining face return air roadway, and part of the return air of the mining face flows out through the roadway between the mining face return air roadway and the panel drainage roadway, thereby realizing the shunt of the return air gas of the mining face and avoiding the gas overrun accident caused by the large amount of gas flowing out through the mining face return air roadway.

[0033] Specifically, the mining face return air roadway and the roadway connected with the panel drainage roadway are the same roadway, and the names of the two are distinguished by the open road transverse river flowing out of the working face return air.

[0034] Specifically, the main air inlet lane of the mining face and the auxiliary air inlet lane of the mining face are located on both sides of the fully mechanized caving face, both of which are air inlet lanes, the main air inlet lane has a large air inlet, and the auxiliary air inlet lane has a small air inlet, the air return lane of the mining face is located on the adjacent side of the auxiliary air inlet lane of the mining face, and the two lanes are connected by a transverse river, and the transverse rivers are temporarily sealed and closed.

[0035] Specifically, the temporary sealing between the transverse rivers is in a closed state under normal circumstances, and when the cut of the working face is mined to a certain sealing wall, the sealing wall is opened to meet the ventilation needs of the air return of the mining face. The last sealing wall pushed by the cut is resealed for air inlet.

[0036] Specifically, a certain sealing wall and the last sealing wall are in terms of the cut advancing position of the fully mechanized caving face, and the sealing wall pushed by the cut is called the last sealing wall. Since the cut of the sealing wall has been pushed, the next sealing wall closest to the cut changes from closed to open, and the last sealing wall changes from open to closed.

[0037] b. The interval between the start of mining in the fully mechanized caving face and the first roof fall in the working face is called the first roof fall in the working face, and the production process before the first roof fall in the working face is called the initial mining in the working face. In addition to the conventional measures of increasing air volume and pre-splitting blasting to release the roof in thin coal seams or medium-thick coal seams, various extraction measures are also used to intercept the gas in the top coal above the mining height.

[0038] The conventional measure of increasing air volume in the initial mining stage is to increase the air supply to the working face by 1.2-1.5 times the designed air volume based on the normal production period ventilation air volume designed according to the working face operation procedure.

[0039] Pre-splitting blasting to release the roof means drilling holes in the pre-released coal body or the upper roof rock layer before the start of mining in the fully mechanized caving face and blasting, and the specific construction process is referred to the published patent with patent number 2016108925387, which discloses a blasting method for forced roof release in a fully mechanized mining face with large mining height and large cut.

[0040] c. Before the working face starts mining, drill sites are constructed in the adjacent lanes on both sides of the working face, and directional interception extraction is carried out in the pre-released coal body above the fully mechanized caving face in the drill sites.

[0041] Drill sites are constructed every certain distance in the two adjacent lanes of the working face, and 2-3 rows of directional long boreholes are constructed in the drill sites to achieve full coverage of the boreholes in the un-fallen coal body of the working face.

[0042] The distance between the drilling fields is generally kept at 50-80m, the drilling field and the roadway have an angle of 5° to 20°, and the drilling field and the roadway horizontal plane have an angle of 30° to 60°, that is, the drilling field is located at the upper part of the roadway and at the upper part of the mining height of the working face, so that the drilling and the long-time gas extraction of the drilling can be realized.

[0043] In the drilling field construction, the drilling machine used is a directional small drilling machine, which can realize a drilling length of 150m or more, and is equipped with a measurement and positioning system while drilling to realize the accurate and quantitative positioning of the drilling trajectory.

[0044] The drilling is located in the un-collapsed coal body above the mining coal seam height of the working face, and a branch hole is constructed at an interval of 30-50m in different directions and trends.

[0045] The drilling field is opened in the roadway near the fully-mechanized caving face, the drilling field and the roadway have an angle, which is generally kept at 5-10°, and the drilling field retreats towards the advancing direction of the working face. The drilling field is constructed along a certain slope above the un-collapsed coal body to be caved in the mining coal seam from the opening, and the slope is generally 10-20°.

[0046] The directional drilling constructed in the roadway on both sides of the fully-mechanized caving face has an angle of 60°-120° with the working face roadway, and there is a spatial overlap and intersection in the un-collapsed coal body above the mining coal seam height, so that the stress release of the top coal body caused by the mining pressure relief can be realized, and the gas in the coal body is released and extracted by the drilling.

[0047] d. Before the working face is mined or during the formation of the working face, a length of 80-100m of the bedding drilling is constructed in the drainage roadway in advance, the drilling is constructed at the top of the roadway wall of the drainage roadway, and the terminal hole of the drilling is located in the different height ranges of the un-collapsed solid coal of the working face.

[0048] The drainage roadway is formed before the working face roadway is constructed, and the coal body above the working face mining height can be pressure relieved and extracted before the roof is collapsed during the initial mining of the fully-mechanized caving face.

[0049] The drilling is arranged along the length range of the working face cut in the direction, the drilling is constructed in two rows or three rows, and is arranged in three flower eyes or five flower eyes, the terminal hole of the drilling in the lower row of the roadway is located in the highest layer, the terminal hole of the uppermost row of the drilling in the roadway is located in the lowest layer, and the different layer drilling is staggered.

[0050] e. In order to prevent the gas in the upper corner of the working face from exceeding the limit, a short drilling is constructed in the un-collapsed coal body above the roadway on one side of the air return roadway of the working face, the drilling faces the advancing direction of the working face, and the coal body is intercepted and extracted before it collapses.

[0051] The short boreholes on one side of the air return roadway are constructed in the initial mining stage, the interval of each row of boreholes is 2-3m, the interval of the boreholes in the same row is 0.5m, and the length of the borehole is determined by the thickness of the un-caved coal above the mining coal seam.

[0052] The boreholes near the coal body on the side of the working face are constructed in the direction of the working face, the boreholes on the side of the solid coal of the working face are appropriately densified, the angle between the boreholes and the air return roadway of the working face is 60°-90°, and the length of the boreholes is appropriately lengthened.

[0053] The boreholes constructed in the air return roadway can be constructed by using the common drill machine.

[0054] The boreholes are constructed in the solid coal above the top of the air return roadway, the angle between the boreholes and the horizontal plane of the roadway is 30-60°, the boreholes are obliquely constructed upwards through the solid coal above, and the terminal holes of the boreholes enter the rock mass above the coal seam.

[0055] Although the embodiments of the present application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A method for preventing gas overrun in initial mining of an ultra-thick coal seam fully-mechanized caving face, characterized in that, Comprising the following steps: a. When planning roadway layout in super-thick coal seam, a main air inlet roadway, a main air return roadway and a panel drainage roadway need to be constructed at the boundary of the mining area, so that the main fully-mechanized caving face in the panel can achieve independent ventilation and realize U-type ventilation; b. The interval between the start of the fully-mechanized caving face and the first roof fall is called the first roof weighting, and the production process before the first roof weighting is called the initial mining of the face. In addition to the conventional measures of increasing air volume and pre-splitting blasting roof caving used in thin or medium-thick coal seams, various gas extraction measures are also used to intercept the gas in the top coal of the mining height; c. Before the working face is mined, a drilling field is constructed in the roadway adjacent to the two sides of the working face, and directional interception and extraction are carried out on the pre-roof caving coal above the mining height in the drilling field. The drilling field is constructed between the two roadways adjacent to the working face, and multiple rows of directional long boreholes are constructed in the drilling field to achieve full coverage of the boreholes on the uncollapsed coal of the working face. The drilling field is opened in the roadway adjacent to the working face, and the drilling field and the roadway are arranged at an angle, with the drilling field retreating in the direction of the working face. The directional boreholes constructed in the roadways on both sides of the fully-mechanized caving face are arranged at an angle, and there is spatial overlap and intersection in the uncollapsed coal above the mining height, which can realize stress release of the top coal due to mining pressure relief, and release and extraction of the gas in the coal by the boreholes; d. Before the working face is mined or during the formation of the working face, a bedding borehole is constructed in the drainage roadway. The borehole is constructed at the top of the roadway wall of the drainage roadway to ensure that the final hole of the borehole is located in different height ranges of the solid coal that has not collapsed in the working face; e. To prevent gas overrun in the upper corner of the working face, a short borehole is constructed in the coal above the roadway on one side of the air return roadway of the working face, and the borehole faces the advancing direction of the working face to achieve interception and extraction before the coal collapses.

2. The method for preventing gas overrun in initial mining of an ultra-thick coal seam fully mechanized caving face according to claim 1, characterized in that, In step a, the main air inlet roadway at the boundary of the panel is connected to the main air inlet roadway, the main air return roadway at the boundary of the panel is connected to the main air return roadway, and the panel air inlet roadway and the mining area air return roadway are connected by the panel drainage roadway to achieve full air pressure ventilation.

3. The method for preventing gas overrun in initial mining of an ultra-thick coal seam fully mechanized caving face according to claim 2, characterized in that, The panel air return roadway is arranged at the boundary of the mining face to achieve appropriate distribution of the air return volume when a large amount of gas is emitted during the production of the mining face, i.e. part of the air return of the mining face flows out through the mining face air return roadway, and part of the air return flows out through the roadway between the mining face air return roadway and the panel drainage roadway to achieve the diversion of the air return gas of the mining face.

4. The method for preventing gas overrun in initial mining of an ultra-thick coal seam fully mechanized caving face according to claim 1, characterized in that, In step b, the conventional measure of increasing air volume during the initial mining stage is to increase the air supply to the working face by 1.2-1.5 times the designed air volume during normal production according to the working face operation procedure.

5. The method for preventing gas overrun in initial mining of an ultra-thick coal seam fully mechanized caving face according to claim 1, characterized in that, In step b, pre-splitting blasting roof caving means that before the fully-mechanized caving face starts mining, holes are drilled in the pre-roof caving coal or the upper roof rock and blasted.

6. The method for preventing gas overrun in initial mining of an ultra-thick coal seam fully mechanized caving face according to claim 1, characterized in that, In step d, the drainage roadway is formed before the working face roadway is constructed, and the coal above the working face is relieved and extracted before the roof collapses during the initial mining of the fully-mechanized caving face.

7. The method for preventing gas overrun in initial mining of an ultra-thick coal seam fully mechanized caving face according to claim 6, characterized in that, The boreholes are arranged along the length of the working face cut, and the boreholes are arranged in two rows or three rows, and are arranged in three flower eyes or five flower eyes, the terminal holes of the boreholes in the lower row of the roadway are located at the highest layer, the terminal holes of the uppermost row of boreholes in the upper part of the roadway are located at the lowest layer, and the boreholes at different layers are staggered.

8. The method for preventing gas overrun in initial mining of an ultra-thick coal seam fully mechanized caving face according to claim 1, characterized in that, In step e, the short boreholes on one side of the air return roadway are constructed in the initial mining stage, and the length of the boreholes is determined according to the thickness of the un-collapsed coal above the height of the mining coal seam; the boreholes are constructed towards the solid coal above the top of the air return roadway, the boreholes are obliquely arranged above the solid coal, and the terminal holes of the boreholes are ensured to enter the rock mass above the coal seam.

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