A method and system for treating the thickening zone of the working face coal seam and the adjacent coal seam with equal thickness

Abstract

A method and system for treating the thickened zone of the working face coal seam and the adjacent coal seam with equal thickness. First, the thickened zone of the coal seam is punched and unloaded by means of hydraulic drilling or hydraulic punching. The volume of the coal body in the thickened zone of the coal seam after unloading is approximately equal to the volume of the coal body in the coal seam with normal thickness. Then, in the thickened zone of the coal seam, the same regional gas control method as that for the coal seam with normal thickness can be adopted, which is beneficial to accurately eliminating the outburst risk in the thickened zone of the coal seam. It is applicable to coal seams that have experienced coal and gas outbursts, have coal and gas outburst risks or are high-gas coal seams, during the preparation process of the working face and before the driving of the coal roadway, during the construction of regional measures for preventing coal and gas outbursts.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas control, and particularly relates to a method and a treatment system for equal-thickness treatment of the thickened zone of the coal seam in the working face and the adjacent coal seam. Background Art

[0002] Article 45 of the "Regulations on the Prevention and Control of Coal and Gas Outbursts" stipulates that regional outburst prevention measures refer to outburst prevention measures taken for a large area of the outburst coal seam before mining and excavation in the outburst coal seam. Regional outburst prevention measures include two categories: mining protective seams and pre-draining coal seam gas. The methods that can be used for pre-draining coal seam gas are: pre-draining coal seam gas by surface wells, and pre-draining sectional coal seam gas by underground cross-cut boreholes or bord-and-pillar boreholes, pre-draining coal roadway strip coal seam gas by cross-cut boreholes, pre-draining coal seam gas in the mining area by bord-and-pillar boreholes or cross-cut boreholes, pre-draining coal seam gas in the coal uncovering area of the cross-cut (including vertical and inclined shafts, etc.) by cross-cut boreholes, pre-draining coal roadway strip coal seam gas by bord-and-pillar boreholes, etc.

[0003] Article 49 of the "Regulations on the Prevention and Control of Coal and Gas Outbursts" stipulates that when taking various pre-draining coal seam gas regional outburst prevention measures, the following requirements shall be met:

[0004] (1) The boreholes for the regional outburst prevention measures of pre-draining sectional coal seam gas by cross-cut boreholes or bord-and-pillar boreholes shall control the entire mining block within the section, the two sides of the return roadways and a certain range of the coal seam outside them. The requirement for the range of the boreholes to control outside the return roadways is: for inclined and steeply inclined coal seam roadways, at least 20 m outside the upper rib contour line and at least 10 m outside the lower rib; for others, at least 15 m outside the contour lines on both sides of the roadway. The above-mentioned borehole control ranges are all distances along the coal seam plane, and the same applies hereinafter;

[0005] (2) The boreholes for the regional outburst prevention measures of pre-draining coal roadway strip coal seam gas by cross-cut boreholes shall control the entire coal roadway and a certain range of the coal seam on both sides. This range is the same as the requirement for the outside of the return roadways in item (1) of this article;

[0006] (3) The boreholes for the regional outburst prevention measures of pre-draining coal seam gas in the mining area by bord-and-pillar boreholes or cross-cut boreholes shall control the coal seam of the entire mining block;

[0007] (4) The regional outburst prevention measures of pre-draining coal seam gas in the coal uncovering area of the cross-cut (including vertical and inclined shafts, etc.) by cross-cut boreholes shall be implemented before the minimum normal distance between the coal uncovering working face and the coal seam is 7 m (the distance shall be appropriately increased in the tectonic damage zone). The minimum control range of the boreholes is: 12 m outside the roadway contour line at the coal uncovering of the cross-cut, vertical shaft and inclined shaft (6 m at the bottom or lower rib of the steeply inclined coal seam), and at the same time, it shall be ensured that the minimum distance from the outer edge of the control range to the roadway contour line (including the contour line of the expected coal uncovering section of the roadway ahead) is not less than 5 m, and when the borehole cannot penetrate the entire coal seam thickness at one time, the minimum advance distance of the coal hole shall be maintained at 15 m.

[0008] Corresponding to actual production, for single, soft coal seams and working faces that do not have the conditions for mining protective layers, due to the soft coal quality and poor stability of the roof, floor and surrounding rock, hole wall collapse is very likely to occur during drilling construction, causing drill sticking and drill burial, resulting in low porosity, which affects the gas extraction effect. In particular, the coal seam thickening zone has high gas pressure and high gas content, and the coal seam thickening zone cannot be discovered by drilling along the layer, which poses a major hidden danger to coal mine safety production. Summary of the invention

[0009] The purpose of the present invention is to provide a method for treating the thickening zone of the coal seam at the working face with the adjacent coal seam to be equal in thickness. The method is used in the underground production process of the coal mine, and on the premise that the thickening zone of the coal seam at the working face is detected, the thickening zone of the coal seam and the adjacent coal seam are treated to be equal in thickness. It is a supplementary measure in the regional measures, which can ensure the safe recovery of the thickening zone of the coal seam and the safety of the underground workers. It is suitable for regional prevention and control measures for coal and gas outbursts in coal seams that have experienced coal and gas outbursts, have outburst hazards or are high in gas, and in the process of working face preparation, and is particularly suitable for single, soft coal seams and coal seam working faces that do not have the conditions for mining protective layers.

[0010] Another object of the present invention is to provide a system for processing the thickened coal seam zone and the adjacent coal seams of equal thickness in a working face suitable for the above method.

[0011] To achieve the above object, the technical solution of the present invention is: a method for treating the thickened zone of a working face coal seam with the adjacent coal seam to be equal in thickness, comprising the following steps:

[0012] Step 1: confirm that the working face has a coal seam thickening zone, and construct a floor rock tunnel under the coal seam; use a drill to construct a through-layer detection borehole vertically toward the roof coal seam every 1.5m in the floor rock tunnel, and the drilling depth must penetrate the coal seam floor by at least 0.5m to detect the thickness h and range d of the coal seam thickening zone;

[0013] Step 2: According to the range of the coal seam thickening zone detected in step 1, calculate and determine the volume of the coal body in the coal seam thickening zone. The top plate length of the coal seam thickening zone is L1, the bottom plate length is L2, the thickness is h, and the width is d. Then the volume of the coal seam thickening zone is ; The normal length of the coal seam in the adjacent area is The volume of the coal seam is V o ;

[0014] Step 3: drill holes upwards through the bottom rock tunnel to the coal seam, arrange the drill holes in a grid pattern, and make the angles between the drill holes the same. Each time, n drill sites are constructed along the coal seam inclination and strike. The drill holes in each drill site are arranged in a fan shape, penetrating 0.5 m from the coal seam roof.

[0015] Step 4: After completing the drilling in Step 3, use the hydraulic punching and cavity - forming equipment. First, conduct primary hydraulic punching and cavity - forming at a position near the roof of the target coal seam using a high - pressure water jet of no less than 25 MPa. Then, conduct hydraulic punching and cavity - forming once every 0.5 m of drill withdrawal until the bottom of the coal seam, finally forming a pressure - relief cavity. This is one cycle.

[0016] Step 5: Repeat the above Steps 1 - 4 until all the coal seams in the coal - seam thickening zone have undergone hydraulic punching and cavity - forming.

[0017] Step 6: During the process of hydraulic cavity - forming, a large amount of soft coal body is washed out. Calculate the volume of the washed - out coal body so that the volume of the coal body in the thickened coal - seam zone after pressure - relief is equal to the volume of the coal body in the normal coal seam.

[0018] The beneficial effects of the present invention are as follows: During the underground coal - mine production process of the present invention, according to relevant omens (the difference in hardness between the roof and floor of the coal seam, the softness of the coal seam, the development of tectonic coal, and the existence of large faults near the working face), 3D seismic exploration or borehole disclosure, it is determined that there is a coal - seam thickening zone in the working face, and the thickness and scope of the coal - seam thickening zone are accurately detected. Then, the coal in the coal seam is unloaded through hydraulic punching and cavity - forming, so that the volume of the coal body in the thickened coal - seam zone after unloading is approximately equal to the volume of the coal body in the coal seam with normal thickness. Then, the coal - seam or gas content in this area is close to that of the adjacent coal body with normal thickness. Finally, by adopting the same regional gas drainage method as the adjacent coal body, after the drainage reaches the standard, safe mining can be achieved.

[0019] A system for equal - thickness treatment of the coal - seam thickening zone and adjacent coal seams in a working face includes a roadway arranged in the rock formation, and a number of weighing belt conveyors and vibrating screens arranged in the roadway.

[0020] The roadway is arranged below the coal - seam thickening zone. Along the roadway's trend, a number of pressure - relief openings are arranged on the roof of the roadway. Inside the pressure - relief openings, a number of hydraulically - formed cavity holes distributed in a fan - shaped pattern are connected. One end of the hydraulically - formed cavity holes extends into the coal seam. The vibrating screen is arranged corresponding to the pressure - relief opening, directly below the pressure - relief opening. A funnel - shaped feeder is arranged at the feeding end of the vibrating screen, and the discharging end is connected to the weighing belt conveyor.

[0021] It also includes a belt conveyor arranged on one side in the roadway. The discharging ends of a number of weighing belt conveyors are connected to the belt conveyor.

[0022] A coal - slag tank is arranged below the vibrating screen.

[0023] The processing system of the present application has a simple structure, is applicable to the equal - thickness treatment method of the present invention, can effectively calculate the coal unloading volume in the coal - seam thickening zone, realize the equal - thickness treatment of the coal seam, and at the same time, after treatment, can drain the coal - seam gas to achieve the goal of safe production. Brief Description of the Drawings

[0024] Figure 1Schematic sectional view of borehole layout for hydraulic punching and cavity formation in the coal seam thickening zone of the working face;

[0025] Figure 2 Schematic diagram of borehole layout for hydraulic punching and cavity formation in the coal seam thickening zone of the working face;

[0026] Figure 3 Schematic diagram of the construction of boreholes for hydraulic punching and cavity formation in the working face;

[0027] Figure 4 Schematic structural diagram of the equal-thickness treatment system of the present application;

[0028] In the figure: 1 - coal seam; 2 - rock stratum; 3 - coal seam thickening zone; 4 - floor rock roadway; 5 - drill rig; 6 - cross-cut borehole; 7 - vibrating screen; 8 - weighing belt conveyor; 9 - belt conveyor. Detailed implementation mode

[0029] The present invention will be further described below with reference to the examples in the accompanying drawings:

[0030] As Figure 4 shown, an equal-thickness treatment system for the coal seam thickening zone and the adjacent coal seam of the working face includes a floor rock roadway 4 arranged in the rock stratum, a plurality of weighing belt conveyors 8 and vibrating screens 7 arranged in the roadway, and a belt conveyor 9

[0031] The floor rock roadway 4 is arranged below the coal seam thickening zone 3. Along the roadway trend, a plurality of pressure relief openings 41 are arranged on the roof of the floor rock roadway 4. Inside the pressure relief openings 41, a plurality of hydraulically formed cavities through cross-cut boreholes 6 are communicated in a fan-shaped distribution. One end of the hydraulically formed cavity extends into the coal seam. The vibrating screen 7 is arranged corresponding to the pressure relief opening 41, directly below the pressure relief opening 41. A funnel-shaped feeder 71 is arranged at the feeding end of the vibrating screen, and the discharging end is connected to the weighing belt conveyor 8. A coal slag tank 72 is arranged below the vibrating screen 7 for collecting coal slag water; the belt conveyor 9 is arranged on one side in the roadway, and the discharging ends of a plurality of weighing belt conveyors are connected to the belt conveyor.

[0032] As Figure 1 shown, a method for equal-thickness treatment of the coal seam thickening zone and the adjacent coal seam of the working face of the present invention discharges coal from the coal seam through hydraulic punching and cavity formation, so that the volume (mass) of the coal body in the coal seam thickening zone after coal discharge is approximately equal to the volume of the coal body in the normal coal seam, and is processed through hydraulic punching and cavity formation. Regional gas drainage measures can be carried out only after the effect inspection meets the standards, so as to achieve the corresponding gas control effect. The specific steps are as follows:

[0033] Step 1, explore or drill the position where the coal seam thickening zone 3 appears in the coal seam 1. At intervals of 1.5 m, use the drill rig 5 to vertically construct detection boreholes (b1, b2, b3... b n), drill through the coal seam roof by at least 0.5 m, and finely detect the thickness (h1, h2, h3…h n ) and the range d of the coal seam thickening zone;

[0034] Step 2, according to the detected average thickness h a and the range d of the coal seam thickening zone, calculate the volume (mass) of the coal body in the coal seam thickening zone. The coal seam thickening zone can generally be equivalent to a trapezoidal area. The length of the roof of the coal seam thickening zone is L1, the length of the floor is L2, the thickness is h a , and the width is d. Then the volume of the coal seam thickening zone is ; The length of the normal coal seam without coal seam thickening in the adjacent area is The volume of the coal seam is V o ;

[0035] Step 3, construct upward cross-cut boreholes 6 from the floor rock roadway to the coal seam, and arrange grid-shaped cross-cut boreholes. The angle α between the boreholes is the same. Each time, a number of drill sites are constructed along the dip and strike of the coal seam. The cross-cut boreholes in each drill site are arranged in a fan shape and penetrate more than 0.5 m above the coal seam roof;

[0036] Step 4, after the cross-cut boreholes are constructed in the floor rock roadway, use the hydraulic punching and cavity-forming equipment. First, use a high-pressure water jet of not less than 25 MPa to conduct primary hydraulic punching and cavity-forming near the roof of the target coal seam, and then conduct hydraulic punching and cavity-forming every 0.3 m of drill withdrawal until the bottom of the coal seam, and finally form a coal unloading cavity. This is one cycle;

[0037] Step 5, repeat the above steps 1-4 until all the coal seam thickening zones are subjected to hydraulic punching and cavity-forming;

[0038] Step 6, during the hydraulic cavity-forming process, a large amount of soft coal body is flushed out. Calculate the volume of the flushed-out coal body through the system of the present invention, so that the volume (mass) of the coal body in the coal seam thickening zone after coal unloading is approximately equal to the volume (mass) of the coal body in the normal coal seam.

[0039] After the construction of equal-thickness treatment of the coal seam thickening zone is completed, it is necessary to adopt the same regional gas drainage method as the adjacent normal coal seam. After the drainage boreholes are constructed, the boreholes need to be centrally sealed. After the borehole sealing is completed, connect to the gas drainage system. After drainage for a period of time, conduct effect inspection on the drained area, including measuring parameters such as residual gas pressure and gas content. Only after the regional measure effect inspection is qualified (drainage meets the standard) can the working face mining operation be carried out.

[0040] The characteristics of the local coal seam thickening zone include: the coal quality is soft, there is a large difference in the hardness between the roof and floor of the coal seam, the permeability of the coal seam is low and the gas extraction is difficult; the gas pressure in the coal seam is high, the gas content is high, and the outburst potential is large. After adopting the method of the present invention, since the coal seam thickness, gas content and gas pressure in the coal seam thickening zone are effectively reduced, it is possible to effectively prevent the sudden outburst or accumulation of the thickening coal seam gas into the mining space, and prevent the occurrence of coal and gas outburst accidents.

Claims

1. A method for equalizing the thickness of the coal seam in the working face with that of the adjacent coal seam, comprising the following steps: Step 1: Confirm that there is a coal seam thickening zone on the working face, and construct a floor rock roadway under the coal seam; every 1.5 m in the floor rock roadway, use a drill to vertically drill through-layer exploration boreholes into the roof coal seam, with the borehole depth penetrating at least 0.5 m below the coal seam floor to detect the thickness h a and width d of the coal seam thickening zone; Step 2: According to the range of the coal seam thickening zone detected in Step 1, calculate and determine the volume of the coal body in the coal seam thickening zone. The length of the roof of the coal seam thickening zone is L1, the length of the floor is L2, and the thickness is h a , the width is d, then the volume of the coal seam thickening zone is ; The length of the normal coal seam in the adjacent area is The volume of the coal seam is Vo; Step 3: Drill upward through - layer boreholes into the coal seam through the floor rock roadway, and arrange the boreholes in a grid - type through - layer pattern. The angle between the boreholes is the same. Each time, construct n drill fields along the dip and strike of the coal seam. The through - layer boreholes in each drill field are arranged in a fan - shape and penetrate 0.5 m through the roof of the coal seam; Step 4: After completing the boreholes in Step 3, use a hydraulic punching and cavity - creating device. First, conduct primary hydraulic punching and cavity - creating at a position near the roof of the target coal seam using a high - pressure water jet with a pressure of not less than 25 MPa. Then, conduct hydraulic punching and cavity - creating every 0.5 m of drill withdrawal until the bottom of the coal seam, and finally form a pressure - relief cavity. So far, it is one cycle; Step 5: Repeat the above Steps 1 - 4 until all the coal seams in the coal - seam thickening zone have been subjected to hydraulic punching and cavity - creating; Step 6, a large amount of soft coal body is flushed out during the hydraulic cavity forming process, calculate the volume of the flushed coal body, so that the volume of the coal body in the thickening zone of the coal seam after coal unloading is equal to the volume Vo of the coal seam with a normal coal seam length of in the adjacent area.

2. The method for equal-thickness treatment of the thickening zone of the working face coal seam and the adjacent coal seam according to claim 1, characterized in that: It includes a roadway arranged in the rock stratum, and a number of weighing belt conveyors and vibrating screens arranged in the roadway, The roadway is arranged below the coal - seam thickening zone. A number of pressure - relief openings are arranged along the roadway strike on the roof of the roadway. A number of hydraulically - created cavity holes distributed in a fan - shape are communicated in the pressure - relief openings. One end of the hydraulically - created cavity holes extends into the coal seam. The vibrating screen is arranged corresponding to the pressure - relief opening, directly below the pressure - relief opening. A funnel - shaped feeder is arranged at the feeding end of the vibrating screen, and the discharging end is connected to the weighing belt conveyor.

3. The method for equal-thickness treatment of the thickening zone of the working face coal seam and the adjacent coal seam according to claim 2, wherein: It also includes a belt conveyor arranged on one side in the roadway. The discharging ends of a number of weighing belt conveyors are connected to the belt conveyor.

4. The method for equal-thickness treatment of the thickening zone of the working face coal seam and the adjacent coal seam according to claim 2, wherein: A coal - slag tank is arranged below the vibrating screen.

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