A safe mining method for rock burst island working face

Abstract

The present invention relates to the field of safe mining of coal mines, and discloses a safe mining method for an isolated working face of a rock burst mine. The coal gangue produced at the bottom of the well is crushed and pulped, and grouting is performed within the design range of the adjacent goaf of the isolated working face. After solidification, the filling body can serve as the supporting coal rock body on both sides of the working face, and the roof of the isolated working face is supported on both sides, so as to solve the problem of high stress concentration during the mining process of the isolated working face, and prevent disasters caused by high stress such as rock burst from occurring during the mining process of the isolated working face. The present invention utilizes the coal gangue produced by the mine to be crushed and pulped to fill a certain range of the goaf on both sides of the isolated working face, and then safely mines the isolated working face. Compared with the existing strip filling mining method, the filling work can be completed continuously at one time, and the coal output efficiency of the working face is high. Compared with the existing solid filling and paste filling, the filling cost is low and the coal gangue generated by underground mining activities can be processed.

Description

Technical Field

[0001] The invention relates to the field of safe mining of coal mines, and in particular to a safe mining method for an isolated island working face in a rock burst mine. Background Art

[0002] Due to the unreasonable design of the working face excavation sequence, the mine generates an isolated working face in the mine field. The isolated working face is subject to the high support pressure formed by the goaf on both sides, resulting in a high degree of stress concentration on the isolated working face. During the mining process, it is very easy to cause disasters such as impact ground pressure and large-scale instability of the tunnel. In addition, the large-scale and high-intensity mining activities in underground coal mines across the country have generated a large amount of coal gangue solid waste. Most of the coal gangue is treated by ground discharge, which not only occupies a large amount of ground land, but also pollutes the soil and groundwater.

[0003] Domestic and foreign scholars have mainly proposed comprehensive utilization technology and strip filling mining technology for isolated working face mining. The comprehensive utilization technology has poor applicability and is difficult to promote. The cost of solid filling and paste filling in strip filling mining is high, and the production capacity of the working face is low. At the same time, a large amount of coal gangue is currently produced underground. It requires a lot of financial and material resources to lift the coal gangue from the bottom of the well to the surface, and the stacking of coal gangue on the surface causes pollution to the soil and environment. Summary of the invention

[0004] In view of the problems of gangue discharge and low mining efficiency of isolated working faces in the prior art, the present invention provides a safe mining method for isolated working faces in rock burst mines, and proposes a mining process for filling the goaf on both sides of the coal gangue slurry for the mining of isolated working faces, which can not only solve the problem of gangue discharge, but also improve the mining efficiency of the isolated working faces and reduce the mining cost. In addition, a grouting walling process in the goaf is proposed for non-horizontal working faces, which solves the problem of slurry continuously flowing from high to low in the goaf due to its own weight.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for safe mining of isolated island working faces in rock burst mines, comprising the following steps:

[0007] Step 1: According to the excavation sequence of the conventional working face and combined with the actual situation on site, the working face retreat channel, return air lane, cut eye and transport lane are excavated to form an isolated working face. Small coal pillars are left in the return air lane, transport lane and adjacent goaf for excavation;

[0008] Step 2, calculating the width of the filling area in the goaf along both sides of the isolated island working face;

[0009] Step 3, according to the width of the filling area in step 2, in the two tunnels of the isolated working face, small coal pillars are drilled and the wall is sprayed between the filling area and the goaf in the adjacent goaf;

[0010] Step 4, after the grouting wall is completed, the filling area is filled with slurry. After the slurry solidifies, the filling bodies on both sides of the isolated working face support the vertical overburden stress of the adjacent goaf of the isolated working face, which facilitates safe mining of the isolated working face.

[0011] Preferably, in step 1, the width of the small coal pillar is 5-8m.

[0012] Preferably, in step 2, the calculation formula for the width of the filling area in the goaf along both sides of the isolated island working face is as follows:

[0013] a×R1=2b×R2

[0014] Among them, a is the width of the island working face; b is the width of the filling area; R1 is the uniaxial compressive strength of the coal body; R2 is the uniaxial compressive strength of the filling body after solidification.

[0015] Preferably, in step 3, the small coal pillar drilling is a spliced ​​hollow drilling, and the small coal pillar drilling steps are as follows:

[0016] Drill holes in the small coal pillars with a diameter of 30 mm, a spacing of 1 m along the tunnel direction, and a distance of 1.5 to 2 m from the bottom plate. Insert directional shotcrete drill rods into the holes to spray and build walls between the filling area and the goaf.

[0017] Preferably, in step 3, the grouting pipe is placed inside the large diameter drill rod during grouting wall construction, and the length of the grouting pipe and the large diameter drill rod are both greater than the sum of the widths of the small coal pillar and the filling area.

[0018] Preferably, in step 3, the slurry material for spraying the wall is an expandable and quick-setting material.

[0019] Preferably, in step 4, the filling steps of the filling area with slurry are as follows:

[0020] The coal gangue at the bottom of the well is crushed, and the coal gangue, fly ash and cement are selected and stirred to obtain a mixed slurry, and an accelerator is added to the mixed slurry to obtain a filling slurry, and the filling slurry is filled into the goaf through a grouting pipe using a hydraulic pump.

[0021] Furthermore, the mass ratio of coal gangue, fly ash and cement is 5:2:1.

[0022] Furthermore, the cement used is silicate cement, and the strength is greater than 32.5R.

[0023] Preferably, in step 4, when the filling area is filled with slurry, a large diameter drill rod is used to be sent into the goaf again along the original drill hole of the small coal pillar, and grouting is performed while withdrawing the drill rod from the inside to the outside.

[0024] Compared with the prior art, the present invention has the following beneficial technical effects:

[0025] The present invention provides a safe mining method for an isolated working face in a rock burst mine. The method comprises the following steps: the coal gangue produced at the bottom of the mine is crushed into pulp, and grouting is performed within the designed range of the goaf adjacent to the isolated working face. After the filling body solidifies, the filling body can serve as supporting coal and rock bodies on both sides of the working face, and support the roof of the isolated working face on both sides, thereby solving the problem of high stress concentration during the mining of the isolated working face and preventing disasters and accidents caused by high stress such as rock burst during the mining of the isolated working face.

[0026] Furthermore, the present invention utilizes the crushing and slurrying of the mine's own coal gangue to fill a certain range of the goaf on both sides of the isolated working face, and then safely recovers the isolated working face. Compared with the existing strip filling mining method, the filling work can be completed continuously at one time, and the coal output efficiency of the working face is high. Compared with the existing solid filling and paste filling, the filling cost is low and the coal gangue generated by underground mining activities can be processed. The grouting wall building process proposed in the present invention can limit the continuous flow of the filling slurry from high to low under the action of its own weight. After the coal gangue is crushed underground, it is prepared into goaf filling material to fill and mine the isolated coal pillar, which not only solves the problem of coal gangue emission, but also ensures the safe recovery of the isolated coal pillar. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the filling position of the goaf areas on both sides of the isolated island working face of the present invention;

[0028] Figure 2 It is a schematic diagram of grouting filling of a non-horizontal working surface according to the present invention. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0030] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0032] See also Figure 1 The present invention provides a safe mining method for isolated working faces in rock burst mines. For the mining of isolated working faces, a coal gangue slurry filling mining process on both sides of the goaf is proposed, which can not only solve the problem of gangue discharge, but also improve the mining efficiency of the isolated working face and reduce the mining cost. In addition, a grouting wall building process in the goaf is proposed for non-horizontal working faces, which solves the problem of slurry continuously flowing from high to low in the goaf due to its own weight.

[0033] The problem of handling coal gangue at the bottom of the well can be solved by crushing and slurrying the coal gangue produced at the bottom of the well, which not only saves the manpower and material costs of transporting the coal gangue to the ground, but also solves the problem of environmental pollution caused by storing coal gangue on the ground.

[0034] See also Figure 2 For non-horizontal working faces, a grouting wall building process is designed before grouting filling. Grouting is carried out in advance in the goaf according to the pre-designed position to form a closed wall, which prevents the filling slurry from continuing to flow to a low level position under the action of its own weight.

[0035] Specifically, the method for safe mining of isolated island working face in rock burst mine comprises the following steps:

[0036] Step 1: According to the excavation sequence of the conventional working face and combined with the actual situation on site, the working face retreat channel, return air lane, cut eye and transport lane are excavated to form an isolated working face. Small coal pillars are left in the return air lane, transport lane and adjacent goaf for excavation;

[0037] Among them, the width of the small coal pillar is 5-8m.

[0038] Step 2, calculating the width of the filling area in the goaf along both sides of the isolated island working face;

[0039] Since the strength of coal bodies and the rock properties of roof and floor plates in different mines vary greatly, the force and support forms of the isolated working face are simplified. In addition, during the mining process of the isolated working face, the rocks in the collapsed zone in the goaf cannot provide effective support to the roof of the goaf in time, and the support effect has a certain lag. Therefore, the support effect of the rocks in the collapsed zone is negligible.

[0040] Among them, the calculation formula for the width of the filling area in the goaf along both sides of the isolated island working face is as follows:

[0041] a×R1=2b×R2

[0042] Among them, a is the width of the island working face; b is the width of the filling area; R1 is the uniaxial compressive strength of the coal body; R2 is the uniaxial compressive strength of the filling body after solidification.

[0043] Step 3, according to the width of the filling area in step 2, in the two tunnels of the isolated working face, small coal pillars are drilled and the wall is sprayed between the filling area and the goaf in the adjacent goaf;

[0044] Specifically, the small coal pillar drilling is a spliced ​​hollow drilling, and the steps of small coal pillar drilling are as follows:

[0045] Drill holes in the small coal pillars with a diameter of 30 mm, a spacing of 1 m along the tunnel direction, and a distance of 1.5 to 2 m from the bottom plate. Insert the directional shotcrete drill rod into the hole to spray and build the wall in the filling area.

[0046] When the grouting wall is built, the grouting pipe is placed inside the large diameter drill rod, and the length of the grouting pipe and the large diameter drill rod is greater than the sum of the widths of the small coal pillar and the filling area.

[0047] The slurry material for shotcrete wall construction adopts expandable and quick-setting materials to ensure the integrity and airtightness of the shotcrete wall.

[0048] Step 4, after the grouting wall is completed, the filling area is filled with slurry. After the slurry solidifies, the filling bodies on both sides of the isolated working face support the vertical overburden stress of the adjacent goaf of the isolated working face, which facilitates safe mining of the isolated working face.

[0049] Among them, the filling steps of slurry filling in the filling area are as follows:

[0050] The coal gangue at the bottom of the well is crushed, and the coal gangue, fly ash and cement are selected and stirred to obtain a mixed slurry, and an accelerator is added to the mixed slurry to obtain a filling slurry, and the filling slurry is filled into the goaf through a grouting pipe using a hydraulic pump.

[0051] Specifically, the mass ratio of coal gangue, fly ash and cement is 5:2:1.

[0052] When filling the filling area with slurry, a large diameter drill rod is used to be sent into the goaf again along the original drill hole of the small coal pillar, and grouting is performed from the inside to the outside while withdrawing the drill rod to ensure the density of the grouting filling in the goaf.

[0053] In the present invention, ordinary Portland cement is used to prepare the slurry in step 4, and the strength is not less than 32.5R. The strength of the slurry filled in the goaf after solidification is not less than 25MPa.

[0054] Example

[0055] a. Tunnel excavation

[0056] Conventional excavation technology is used to excavate the return air tunnel, transport tunnel, cutting eye and withdrawal passage of the isolated working face. Small coal pillars are left for excavation in the return air tunnel, transport tunnel and adjacent goaf, with a coal pillar width of 6m.

[0057] b. Filling width calculation

[0058] Assuming the width a of the isolated working face is 300m, the uniaxial compressive strength R1 of the coal body is 10MPa, the uniaxial compressive strength R2 of the filling body after solidification is 60MPa, and the working face is simplified to be horizontal, then the deadweight of the overburden per unit area of ​​the filling body and the coal body is the same. Therefore, the width b of one side of the filling body can be determined to be 25m by the following formula.

[0059] a×R1=2b×R2

[0060] c. Shotcrete wall construction

[0061] In the two tunnels of the working face, large-diameter hollow drill rods are used to drill holes in the small coal pillars. The diameter of the holes is 30 mm, the spacing between holes is 1 m along the direction of the tunnel, and the holes are 1.5 to 2 m away from the bottom plate.

[0062] After the drill rod penetrates the coal pillar, continue to splice the drill rod until the drill bit contacts the designed surface of the shotcrete wall. After the drilling is completed, do not pull out the drill rod for the time being, insert the shotcrete pipe equipped with a multi-directional shotcrete head into the drill rod, and push the shotcrete pipe until the shotcrete head is less than 20mm away from the designed surface of the shotcrete wall. Stop pushing the shotcrete pipe, start the shotcrete pump, and spray the pre-prepared expansion quick-setting slurry through the multi-directional nozzle to the designed surface of the shotcrete wall to form a closed wall.

[0063] d. Preparation of filling slurry

[0064] The coal gangue is crushed at the bottom of the well. The maximum particle size of the crushed coal gangue shall not exceed 15mm, and the proportion of gangue with a particle size of 0-5mm shall not be less than 50%. The ratio of coal gangue: fly ash: cement is 5:2:1. Accelerator is added to prepare the filling slurry. The prepared slurry should be stirred in the mixer for use to prevent solidification.

[0065] e. Grouting filling

[0066] Use a large diameter drill rod to drill again at the location of the original drill hole in the small coal pillar, and stop drilling when the drill bit reaches the filling design line. Push the grouting head and grouting pipe into the drill rod, and start grouting after the grouting head reaches the filling design line. During the grouting process, pull the grouting pipe out of the drill rod at a uniform speed, and control the pulling speed of the grouting pipe according to the grouting volume and the grouting pipe slurry discharge speed. Repeat this grouting process, and grout through the small coal pillars in sequence along the direction of the roadway.

[0067] f. Mining

[0068] After the filling solidifies for 28 days, the isolated island working face will be mined normally.

[0069] In summary, the present invention provides a safe mining process for an isolated working face, which mainly utilizes the crushing and slurrying of the coal gangue produced by the mine to fill a certain range of the goaf on both sides of the isolated working face, and then safely mines the isolated working face. Compared with the existing strip filling mining method, the filling work can be completed continuously at one time, and the coal output efficiency of the working face is high. Compared with the existing solid filling and paste filling, the filling cost is low and the coal gangue generated by underground mining activities can be processed. The grouting wall building process proposed in the present invention can limit the continuous flow of the filling slurry from high to low under the action of its own weight. After the coal gangue is crushed underground, it is prepared into a goaf filling material to fill and mine the isolated coal pillar, which not only solves the problem of coal gangue emission, but also ensures the safe mining of the isolated coal pillar.

[0070] 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 it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A safe mining method for isolated island working face in rock burst mine, characterized in that: The steps include: Step 1: According to the excavation sequence of the conventional working face and combined with the actual situation on site, the working face retreat channel, return air lane, cut eye and transport lane are excavated to form an isolated working face. Small coal pillars are left in the return air lane, transport lane and adjacent goaf for excavation; Step 2, calculating the width of the filling area in the goaf along both sides of the isolated island working face; The calculation formula for the width of the filling area in the goaf along both sides of the isolated working face is as follows: Among them, a is the width of the island working face; b is the width of the filling area; R1 is the uniaxial compressive strength of the coal body; R2 is the uniaxial compressive strength of the filling body after solidification; Step 3, according to the width of the filling area in step 2, in the two tunnels of the isolated working face, small coal pillars are drilled and the wall is sprayed between the filling area and the goaf in the adjacent goaf; The drilling of small coal pillars is a spliced ​​hollow drilling. The steps of drilling small coal pillars are as follows: Drill holes in the small coal pillars with a diameter of 30 mm, a spacing of 1 m along the tunnel direction, and a distance of 1.5 to 2 m from the bottom plate. Insert the directional shotcrete drill rod into the borehole to spray the wall between the filling area and the goaf. When the grouting wall is built, the grouting pipe is placed inside the large diameter drill pipe, and the length of the grouting pipe and the large diameter drill pipe is greater than the sum of the width of the small coal pillar and the filling area; The slurry material for shotcrete wall construction is expandable and quick-setting material; Step 4, after the grouting wall is completed, the filling area is filled with slurry. After the slurry solidifies, the filling bodies on both sides of the isolated working face support the vertical overburden stress of the adjacent goaf of the isolated working face, which facilitates safe mining of the isolated working face.

2. A method for safe mining of isolated island working faces in rock burst mines according to claim 1, characterized in that: In step 1, the width of the small coal pillar is 5-8m.

3. The safe mining method for isolated island working face in rock burst mine according to claim 1, characterized in that: In step 4, the filling steps of the filling area are as follows: The coal gangue at the bottom of the well is crushed, and the coal gangue, fly ash and cement are selected and stirred to obtain a mixed slurry, and an accelerator is added to the mixed slurry to obtain a filling slurry, and the filling slurry is filled into the goaf through a grouting pipe using a hydraulic pump.

4. A method for safe mining of isolated island working faces in rock burst mines according to claim 3, characterized in that: The mass ratio of coal gangue, fly ash and cement is 5:2:

1.

5. A method for safe mining of isolated island working face in rock burst mine according to claim 4, characterized in that: The cement used is silicate cement with a strength greater than 32.5R.

6. The safe mining method for isolated island working face in rock burst mine according to claim 1, characterized in that: In step 4, when the filling area is filled with slurry, a large diameter drill rod is used to be sent into the goaf again along the original drill hole of the small coal pillar, and grouting is performed while withdrawing the drill rod from the inside to the outside.

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