A gas drainage method by means of raise boring for gas emission from a fully-mechanized caving face in a very thick coal seam with slicing

Abstract

The present invention belongs to the field of gas drainage, and relates to a method for gas drainage from a reverse well in a fully mechanized top coal caving face with slicing mining in extra-thick coal seams. It can solve the problem of excessive gas in the upper corner of the first slice in the fully mechanized top coal caving face with slicing mining in extra-thick coal seams. While constructing a reverse well in the bottom drainage roadway to control the gas in the upper corner and goaf, it can also pre-drain the gas in the coal body of the lower slice, and has broad prospects in the field of gas control in coal seam mining under different gas component conditions.

Description

Technical Field

[0001] The invention belongs to the field of gas drainage, and relates to a method for reverse well drainage of gas gushing from the working face of fully-mechanized top coal caving mining in extra-thick coal seams with slicing. Background Art

[0002] Most of the fully-mechanized top coal caving mining mines in extra-thick coal seams are high-gas mines. The fully-mechanized top coal caving mining working face has the following characteristics: ① large production capacity and high absolute gas gushing volume; ② gas is easy to accumulate at the upper corner, and the accumulation degree is large; ③ the gas gushing volume in the goaf increases. The above characteristics lead to large gas gushing from the fully-mechanized top coal caving mining working face, and even frequent overlimit accidents occur.

[0003] In view of the problem of large gas gushing from the fully-mechanized top coal caving mining working face in extra-thick coal seams, during the mining process, methods such as surface wells, high-level gas drainage headings in the roof, and gas drainage by burying pipes at the upper corner are mainly used to control the pressure-relieved gas and the gas in the goaf. Among the above methods, (1) surface well drainage has problems such as large construction difficulty, high cost, and difficult maintenance; (2) high-level gas drainage headings in the roof and large-diameter directional boreholes in the roof are mainly used to drain the fissure gas in the goaf. High-level gas drainage headings in the roof have the disadvantages of long construction period and high cost, and large-diameter directional boreholes in the roof have the disadvantages of difficult borehole hole protection and poor drainage effect. Moreover, both methods have a certain drainage effect on coal seams with CH4 as the main gas component. Since the density of CH4 gas is small and it is easier to accumulate in the roof fissures, a better drainage effect can be achieved. However, for mines with CO2 as the main gas component, due to the large density of CO2 gas, it is easier to accumulate in the lower middle part of the goaf, and high-level gas drainage headings in the roof and large-diameter directional boreholes in the roof are generally about 10 - 30 m above the coal seam. Therefore, the drainage effect for the CO2 in the goaf and fissures is poor; (3) burying pipes at the upper corner is mainly used to drain the gas in the goaf near the upper corner. The pure drainage volume of burying pipes at the upper corner is generally 0.5 - 2 m3 / min, and the drainage volume is limited and not enough to solve the overlimit problem at the upper corner. It is generally used as an auxiliary measure. To sum up, the currently commonly used methods mainly aim at controlling the gas gushing from the first slice, and do not effectively control the pressure-relieved and discharged gas generated in the lower slices. Summary of the Invention

[0004] In view of this, the purpose of the invention is to provide a method for reverse well drainage of gas gushing from the working face of fully-mechanized top coal caving mining in extra-thick coal seams with slicing, which can achieve the simultaneous control of the overlimit problem of gas gushing from the working face of the first slice and the drainage of the pressure-relieved gas in the lower slices.

[0005] To achieve the above purpose, the invention provides the following technical solution: A method for reverse well drainage of gas gushing from the working face of fully-mechanized top coal caving mining in extra-thick coal seams with slicing, including the following steps:

[0006] S1, after the excavation of the first layer return air chute and the bottom extraction lane of the return air chute is completed, several reverse wells are constructed in the return air chute from the bottom extraction lane of the return air chute to the bottom plate of the return air chute by using a reverse well drilling rig;

[0007] S2, after the well construction is completed, the hole protection screen pipe is lowered into the well;

[0008] S3, use a circular iron mesh to wrap the wellhead, and cover the iron mesh with a wind tube cloth to prevent pedestrians from stepping in and causing wind disturbance;

[0009] S4, connect all the reverse wells to the drainage pipeline in the bottom drainage lane of the return air chute, with a drainage negative pressure of 80~100kpa, and start to drain the coal body fissure gas in the lower layer;

[0010] S5, when the working face is mined, the wind tube cloth on the reverse well is immediately removed, and the first reverse well starts to extract gas from the upper corner of the working face and the goaf, while taking into account the extraction of gas inside the lower layer coal body. The reverse well in front of the working face still mainly extracts gas inside the lower layer coal body;

[0011] S6. When the working face is mined to the second wellbore, remove the wind tube cloth on the second wellbore and close the extraction valve of the first wellbore to prevent the negative pressure extraction of the first wellbore from causing spontaneous combustion in the goaf. As the working face advances forward, the remaining wellbores are operated according to this step until the working face is mined.

[0012] Optionally, the diameter of the reverse well is 1~1.2m.

[0013] Optionally, the reverse shafts are arranged at intervals of 30 to 50 m, with the first reverse shaft being arranged at the corner behind the cut eye.

[0014] Optionally, the hole opening of the hole-protecting screen pipe is flush with the bottom plate of the return air chute.

[0015] The beneficial effects of the present invention are as follows: the present invention provides a reverse well extraction method for gas outburst in a fully-mechanized caving mining working face of an extremely thick coal seam, which can simultaneously extract gas from the upper corner and goaf in reverse well construction during bottom extraction tunnel construction, and can pre-extract gas from the lower stratified coal body. Compared with the techniques of ground well extraction, roof high extraction tunnel extraction, and large-diameter directional drilling on the roof, the method has high efficiency and low cost in controlling excessive gas accidents in the upper corner.

[0016] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, wherein:

[0018] Figure 1 is the overall plan view of the present invention;

[0019] Figure 2 is the overall sectional view of the present invention;

[0020] Figure 3 is the diagram of raise boring drainage of the present invention.

[0021] Reference numerals: 1 - return air crossheading, 2 - mining line, 3 - goaf, 4 - bottom gas drainage roadway in return air crossheading, 5 - raise bore, 51 - first raise bore, 52 - second raise bore, 53 - third raise bore, 54 - fourth raise bore, 55 - fifth raise bore, 56 - sixth raise bore, 6 - hole protection screen pipe, 7 - circular iron net, 8 - air duct cloth, 9 - gas drainage pipeline, 10 - lower slice, 11 - goaf gas, 12 - gas inside lower slice coal body, 13 - gas drainage valve. Specific embodiments

[0022] The following specific examples illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0023] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and should not be construed as limitations on the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will 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 in the drawings may be omitted.

[0024] 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 the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position 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.

[0025] See also Figures 1 to 3 , which is a method for gas emission reverse well extraction in a fully mechanized caving mining working face of an extra-thick coal seam, comprising the following steps:

[0026] S1. After the excavation of the first-layer return air chute 1 and the return air chute bottom extraction lane 4 is completed, a reverse well 5 is constructed from the return air chute bottom extraction lane 4 to the bottom plate of the return air chute 1 using a reverse well drilling rig. The diameter of the reverse well 5 is 1~1.2m;

[0027] S2, there are 6 reverse shafts 5, namely 51-first reverse shaft, 52-second reverse shaft, 53-third reverse shaft, 54-fourth reverse shaft, 55-fifth reverse shaft, 56-sixth reverse shaft, and the 6 reverse shafts 5 are arranged at a spacing of 30-50m, among which the first reverse shaft 51 is arranged at the corner behind the cut-eye;

[0028] After the construction of S3 and the reverse shaft 5 is completed, the hole-protecting screen pipe 6 is lowered into the reverse shaft throughout the entire process, and the hole position of the hole-protecting screen pipe 6 is flush with the bottom plate of the return air chute 1;

[0029] S4, using a circular iron net 7 to wrap the wellhead of the anti-well 5, and at the same time covering the iron net with a wind tube cloth 8 to prevent pedestrians from stepping in and causing wind turbulence;

[0030] S5, connect all the reverse wells 5 to the extraction pipeline 9 in the bottom extraction lane 4 of the return air chute, extract negative pressure 80~100kpa, and start to extract the coal body fissure gas in the lower layer 10;

[0031] S6. When the working face is mined, the wind tube cloth 8 on the reverse shaft 51 is immediately removed, and the first reverse shaft 51 starts to extract gas 11 in the upper corner of the working face and the goaf, and gas 12 inside the lower layer coal body. The reverse shafts (52, 53, ...) in front of the mining still mainly extract gas 12 inside the lower layer coal body;

[0032] S7. When the working face advancing line reaches the second raise 52, remove the upper air duct cloth 8 of the second raise 52, and close the drainage valve 13 of the first raise 51 to prevent spontaneous combustion in the goaf 3 caused by the negative pressure drainage effect of the first raise 51. As the working face advances forward, the remaining raises are all operated according to this procedure until the end of the working face mining.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and all of them should be covered by the scope of the claims of the present invention.

Claims

1. A gas drainage method by means of an inverse well for gas emission from a fully mechanized caving face in a very thick coal seam, characterized in that, It includes the following steps: S1. After the driving of the first-level return airway and the bottom gas drainage roadway of the return airway is completed, several raise bores are constructed from the bottom gas drainage roadway of the return airway to the floor of the return airway in the return airway by using a raise boring machine; S2. After the raise bore construction is completed, a hole protection screen pipe is inserted throughout the raise bore; S3. The wellhead of the raise bore is wrapped with a circular iron net, and at the same time, a ventilation duct cloth is covered on the iron net to prevent pedestrians from stepping in and causing air flow disorder; S4. All the raise bores are connected to the gas drainage pipeline in the bottom gas drainage roadway of the return airway, with a drainage negative pressure of 80-100 kPa, and the gas in the coal seam fissures of the lower slice is drained; S5. When the working face is mined, the upper ventilation duct cloth of the raise bore is immediately removed, and the first raise bore starts to drain the gas in the upper corner and the goaf of the working face, while taking into account the drainage of the gas inside the coal body of the lower slice. The raise bores in front of the working face still mainly drain the gas inside the coal body of the lower slice; S6. When the working face is mined to the second raise bore, the upper ventilation duct cloth of the second raise bore is removed, and the drainage valve of the first raise bore is closed to prevent spontaneous combustion of the goaf caused by the negative pressure drainage of the first raise bore. As the working face advances forward, the remaining raise bores are all operated according to this step until the mining of the working face is completed.

2. A gas drainage method by inverse well for gas emission in a fully-mechanized top coal caving face with extra-thick coal seams according to claim 1, characterized in that: The diameter of the raise bore is 1-1.2 m.

3. A gas drainage method for a reverse well in a fully-mechanized caving face with slicing mining in an extra-thick coal seam according to claim 1, characterized in that: The raise bores are arranged at intervals of 30-50 m, and the first raise bore is arranged at the corner behind the cutting eye.

4. A gas drainage method for an inverted well in a fully mechanized caving face of a very thick coal seam by slicing, according to claim 1, characterized in that: The orifice position of the hole protection screen pipe is flush with the floor of the return airway.

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