A method for fully mechanized caving and re-mining in coal mine goaf area

Abstract

The present invention belongs to the field of coal mining methods, and specifically relates to a method for fully mechanized caving and re-mining in a coal mine goaf area. The method comprises mining the upper coal seam and the middle coal seam together using a fully mechanized caving process, mining the middle coal seam, caving the upper coal seam, and setting a mining roadway in the middle coal seam to arrange a standard fully mechanized caving working face. Simultaneously, the filling process is determined based on the volume ratio of the mined coal. For goaf areas where caving is performed due to a high coal volume ratio, high-water-density materials are used to ensure the strength of the filling. For goaf areas where caving is performed due to a low coal volume ratio, gangue blocks are used to fill. Furthermore, all goaf areas in the lower coal seam are filled with high-water-density materials. The present invention can simplify the mining process of the upper coal seam, reduce the workload of roadway excavation, arrange a standard working face, improve mining efficiency, reduce mining costs, and solve the problem of re-mining and re-mining of coal seams affected by goaf areas.

Description

Technical Field

[0001] The invention belongs to the field of coal mining methods, and in particular relates to a fully mechanized caving and re-mining method in a coal mine goaf area. Background Art

[0002] Small coal mines are not formally mined and generally adopt the tunnel mining method, that is, mining the coal seam in the form of digging a tunnel in the coal seam. This mining method can simplify the support process or even eliminate support, saving support costs and mining equipment costs. However, this mining method is inefficient, has a low recovery rate and poor safety. After mining in small coal mines, a tunnel mining area including empty tunnels and coal pillars will be formed in the coal seam.

[0003] After the integration of small coal mines, the coal seams that have been mined without a plan will be subsequently re-mined in a regular manner, such as using a comprehensive mechanized coal mining process. However, the existing goaf will have an impact on the subsequent mining process and mining plan. For example, if the goaf is located above the coal seam to be mined and the distance is relatively close, it is easy to cause roof collapse accidents when mining the coal seam to be mined; if the goaf is located below the coal seam to be mined and the distance is relatively close, it will form a step-out mining situation, which is easy to cause floor collapse accidents when mining the coal seam to be mined; if the coal seam where the goaf is located is the coal seam to be mined, it is necessary to consider the ability of the coal pillars in the goaf to withstand the advance support pressure, as well as the stability of the roof when the coal pillars in the goaf are mined using a comprehensive mechanized coal mining process.

[0004] If the completely unmined coal seam is a middle coal seam, and the upper and lower coal seams adjacent to it have all been mined in small coal kilns, there are goaf areas in the lanes. For this complex mining condition, how to plan the mining sequence of the coal seams and how to pass through the goaf areas during coal seam mining, and how to ensure mining safety and mining efficiency become technical difficulties that need to be overcome. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention proposes a method for fully mechanized caving and mining in a coal mine, which comprises the following steps:

[0006] S1: Excavate coal transport tunnel and material transport tunnel along the strike in the middle coal seam, and excavate cut holes to connect the coal transport tunnel and material transport tunnel to form a fully mechanized caving working face;

[0007] S2: Determine the mining height and height reduction of the fully mechanized caving working face. The mining height part is the middle coal seam and part of the interbedded gangue layer, and the height reduction part is part of the interbedded gangue layer and the upper coal seam.

[0008] S3: For each goaf area in the upper coal seam, assuming that caving is performed, calculate the volume ratio of the upper coal seam objects to other non-coal objects; caving is performed on goaf areas whose volume ratio reaches a first threshold, while caving is not performed on goaf areas that do not reach the first threshold, and only the high-mined portion is mined; caving is performed on upper coal seam areas where no goaf areas exist;

[0009] S4: For the goaf of the roadway where caving is being carried out, high-water-repellent material and water are injected into the top empty roadway in the goaf, and the strength of the high-water filling body is made equal to that of the upper coal seam;

[0010] For goafs where no caving is carried out, gangue blocks of different particle size distributions are filled into the top goaf of the goaf, and the expansion coefficient of the gangue blocks after collapse is the same as that of the upper coal seam after collapse;

[0011] S5: For each goaf in the lower coal seam, inject high-water-density material and water into the bottom goaf, and make the strength of the high-water-density filling body the same as that of the lower coal seam;

[0012] S6: The fully mechanized caving technology is used to mine the fully mechanized caving working face; the goaf of the tunnel filled with waste rock blocks is not mined.

[0013] Preferably, the method further includes S7: mining the lower coal seam using a comprehensive mechanized one-time full-height mining process;

[0014] Alternatively, the coal mining equipment used in the fully mechanized caving working face can be used to mine the lower coal seam using the fully mechanized caving technology, and the caving height should be greater than the height of the bottom empty roadway.

[0015] Preferably, in step S7, when the comprehensive caving technology is adopted, for each goaf in the lower coal seam, it is assumed that caving is to be carried out, and the volume ratio of the lower coal seam objects to be mined and other non-coal objects is calculated; caving is carried out for the goaf whose volume ratio reaches the second threshold, and caving is not carried out for the goaf that does not reach the second threshold.

[0016] The beneficial effects of the present invention are: 1. The present invention is aimed at the working conditions of extremely close coal seam groups, and there are goafs in the upper coal seam, the middle coal seam is intact, and there are goafs in the lower coal seam. The upper coal seam and the middle coal seam are mined together using the comprehensive mining process, wherein the middle coal seam is mined and the upper coal seam is mined; the recovery tunnel is arranged in the middle coal seam, and the middle coal seam can be used to arrange a standard comprehensive mining working face; there is no need to mine the goafs in the tunnels with high recovery rates, and mining is performed on the goafs in the tunnels with low recovery rates. Compared with arranging a comprehensive mining working face alone for mining the upper coal seam, the mining process of the upper coal seam can be simplified and the workload of tunnel excavation can be reduced.

[0017] 2. Furthermore, different filling processes are adopted for filling the goaf of the upper coal seam roadway according to whether mining is carried out or not; for the goaf of the roadway where mining is carried out, due to the addition of the mining process, the recovery speed of the comprehensive caving working face is slow, and the roof needs to maintain strength for a longer time, so high-water-content materials are used for filling to ensure the strength of the filling body; while the goaf of the roadway where mining is not carried out is filled with gangue blocks. Since the gangue blocks can be obtained locally and do not require cementation, the cost is low, and since no mining is carried out, the comprehensive caving working face advances quickly, the requirements for the roof strength are reduced, and low-strength gangue blocks can be used for filling; in addition, the use of gangue blocks for filling can make its crushing expansion coefficient after collapse the same as that of the upper coal seam, ensuring the stability of the roof falling.

[0018] 3. For the goaf areas of the lower coal seam, all high-water-density materials are used to ensure the strength of the filling body to ensure the stability of the floor when the middle coal seam is mined; at the same time, since the goaf areas generated after the upper coal seam and the middle coal seam are mined are close to the lower coal seam, the high-water-density filling body can ensure that there are rock layers of sufficient thickness and strength to isolate the lower coal seam from the upper goaf area, thereby reducing the risk of roof collapse when mining the lower coal seam. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the stratum structure of the coal mine goaf area of the present invention;

[0020] Figure 2 This is a schematic plan view of the layout of the mining roadway in the fully mechanized caving working face of the present invention;

[0021] Figure 3 This is a schematic plan view of the relative position relationship between the goaf of No. 9 coal lane and the fully mechanized caving working face mining laneway of the present invention;

[0022] Figure 4 This is a schematic plan view of the relative position relationship between the goaf area of No. 11 coal lane and the fully mechanized caving working face mining laneway of the present invention;

[0023] In the figure, limestone roof 1; 9# coal 2; shale interbedded gangue 3; 10# coal 4; shale floor 5; 11# coal 6; coal transport lane 7; cutting eye 8; material transport lane 9; coal transport up the mountain 10; material transport up the mountain 11; top empty lane 12; top coal pillar 13; bottom empty lane 14; bottom coal pillar 15; fully mechanized caving working face 16. DETAILED DESCRIPTION

[0024] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0025] like Figure 1 、 Figure 3-Figure 4As shown, there are three coal layers in the Sanpan area of Liuwan Coal Mine of Fenxi Mining Group, namely 9# Coal 2, 10# Coal 4 and 11# Coal 6, with thicknesses of 1.5m, 1.85m and 4.9m respectively. All of them are nearly horizontal coal seams with a dip angle of about 4°; the upper part of 9# Coal 2 is a limestone roof 1 with a thickness of 5.0m; between 9# Coal 2 and 10# Coal 4 is a shale interbedded gangue layer 3 with a thickness of 2.15m; between 10# Coal 4 and 11# Coal 6 is a shale floor 5 with a thickness of 4.4m; part of 9# Coal 2 and 11# Coal 6 are mined by small coal mines using the tunnel mining technology, forming tunnel goaf areas. The tunnel goaf area in 9# Coal 2 includes the top tunnel 12 and the top coal pillar 13. The goaf area in 11# coal 6 includes the bottom goaf 14 and the bottom coal pillar 15. 10# coal 4 is a complete unmined coal seam; the top goaf 12 is 1.5m high and 2.2m wide; the bottom goaf 14 is 1.8m high and 2.2m wide. The bottom goaf 14 is mined along the top surface of 11# coal 6, and the lower part of the bottom goaf 14 is the unmined part of 11# coal 6; based on the thickness of 9# coal 2, 10# coal 4 and 11# coal 6, the thickness and strength of the top and bottom plate rock layers, the thickness and strength of the interbedded gangue layer, and the scope of the goaf area, the following mining method is proposed. Under the premise of ensuring safe mining, the mining efficiency and mining benefits can be maximized.

[0026] Specifically, the present invention proposes a method for fully-mechanized top coal caving and re-mining in a coal mine goaf area, wherein fully-mechanized top coal caving refers to a comprehensive mechanized top coal caving mining process, which is a mining method well known in the coal mining field; re-mining refers to the re-mining of the unmined portion of a mined coal seam due to incomplete mining, which is a technical term well known in the art; goaf area refers to the mined goaf area below the mining working face, which is a technical term well known in the art. For example, in this embodiment, there is a goaf area of the 11# coal 6 lane below the fully-mechanized top coal caving working face 16. For the fully-mechanized top coal caving working face 16, the goaf area of the 11# coal 6 lane is the goaf area;

[0027] The method for fully mechanized caving and mining in a coal mine goaf area comprises the following steps:

[0028] S1: If Figure 2-Figure 4 As shown, in the 10# coal 4, a coal transport tunnel 7 is excavated along the strike by the coal transport uphill 10, and a material transport tunnel 9 is excavated along the strike by the material transport uphill 11. A cut hole 8 is excavated to connect the coal transport tunnel 7 and the material transport tunnel 9 to form a fully-mechanized caving working face 16; the fully-mechanized caving working face 16 has a strike length of 800m and a dip length of 204m. Taking the 10# coal 4 as a reference, the average buried depth of the fully-mechanized caving working face 16 is 114.8m. The strike and dip are well-known technical terms in the field of geological and mining engineering and will not be explained here.

[0029] S2: Determine the mining height and caving height of fully mechanized caving working face 16. Fully mechanized caving working face 16 adopts fully mechanized caving technology for mining. The designed mining height is 2.35m, including the height of the entire 10# coal 4 and the height of 0.5m below the shale interbedded gangue layer 3; the designed caving height is 3.15m, including the height of 1.65m above the shale interbedded gangue layer 3 and the height of the entire 9# coal 2.

[0030] S3: For each goaf in 9# coal 2, assuming that caving is performed, the mined volume of the top empty goaf 12 is determined based on the height, width, and total length of the top empty goaf in the goaf. Further, based on the plane area of the goaf, combined with the heights of 9# coal 2, shale interlayer 3, and 10# coal 4, as well as the designed mining height and caving height, the volume ratio of 9# coal 2 mined in the goaf to other non-coal objects (shale interlayer 3 and high-water filling) is calculated; goafs whose volume ratio reaches a first threshold are caving, and goafs that do not reach the first threshold are not caving, and only the 2.35m portion of the designed mining height is mined; other 9# coal 2 areas where no goaf exists are caving, and the range of the first threshold is 0.3-0.4;

[0031] S4: For the goaf of the lane where caving is being carried out, high-water-density material and water are injected into the top empty lane 12 in the goaf, and the strength of the high-water-density filling body formed is adjusted by adjusting the ratio of high-water-density material to water, so that the strength of the high-water-density filling body is the same as that of 9# coal 2;

[0032] For the goaf of a roadway where only the designed mining height portion is mined without caving, gangue blocks of different particle sizes and gradations are filled into the top empty roadway 12 in the goaf. By adjusting the particle size and gradation of the gangue blocks, the crushing expansion coefficient of the gangue blocks after collapse is the same as that of the 9# coal 2 after collapse. Coal has low strength and a small crushing expansion coefficient, while gangue blocks have high strength and a large crushing expansion coefficient. However, there are gaps between the gangue blocks. Therefore, by adjusting the particle size and gradation of the gangue blocks, the crushing expansion coefficient can be achieved to be the same as that of the 9# coal 2 after collapse.

[0033] S5: For each goaf in the 11# coal 6, high-water-density material and water are injected into the bottom empty goaf 14, and the strength of the formed high-water-density filling body is adjusted by adjusting the ratio of high-water-density material to water, so that the strength of the high-water-density filling body is the same as that of the 11# coal 6;

[0034] S6: The fully mechanized caving technology is used to mine the fully mechanized caving working face 16, with a mining height of 2.35m and a caving height of 3.15m; the goaf of the tunnel filled with waste rock blocks is not mined, and only the 2.35m part of the designed mining height is mined.

[0035] Furthermore, the fully mechanized top-coal caving mining method for a coal mine in a goaf area of the present invention further includes the step of recovering the goafed 11# coal 6, specifically:

[0036] S7: Design a mining face in No. 11 coal 6, adopt comprehensive mechanized one-time mining full-height process, and the mining height is 4.9m;

[0037] Alternatively, the coal mining equipment used in the fully mechanized caving working face 16 is used to adopt the fully mechanized caving process for mining, with a mining height of 2.5m and a caving height of 2.4m, which is greater than the height of the bottom empty roadway 14; for each goaf area in the 11# coal 6, assuming that caving is performed, the volume ratio of the mined 16# coal 6 to other non-coal objects (high-water filling bodies) is calculated; if the volume ratio reaches the second threshold, the goaf area of the goaf is mined; if the second threshold is not reached, the goaf area of the goaf is not mined, and only the 2.5m part of the designed mining height is mined; the 16# coal 6 area where there is no goaf is mined; in this embodiment, the range of the second threshold is 0.4-0.5.

[0038] Of course, the above description is only a preferred embodiment of the present invention, and the present invention is not limited to the above-mentioned embodiments. It should be noted that all equivalent substitutions and obvious deformation forms made by any technician familiar with this field under the guidance of this specification fall within the substantive scope of this specification and should be protected by the present invention.

Claims

1. A method for fully mechanized caving and mining in a coal mine, characterized in that: The following steps are involved: S1: Excavate coal transport tunnel and material transport tunnel along the strike in the middle coal seam, and excavate cut holes to connect the coal transport tunnel and material transport tunnel to form a fully mechanized caving working face; S2: Determine the mining height and height reduction of the fully mechanized caving working face. The mining height is 2.35m for the middle coal seam and part of the interbedded coal seam, and 3.15m for the part of the interbedded coal seam and the upper coal seam. The thicknesses of the upper coal seam, interbedded coal seam, and lower coal seam are 1.5m, 2.15m, and 1.85m, respectively. S3: For each goaf in the upper coal seam, if caving is to be performed, the volume ratio of the upper coal seam objects to other non-coal objects is calculated; goafs whose volume ratio reaches a first threshold are caved, while goafs that do not reach the first threshold are not caved and only the mined height portion is mined; caving is performed on upper coal seam areas where no goaf exists; the range of the first threshold is 0.3-0.4; S4: For the goaf of the roadway where caving is being carried out, high-water-repellent material and water are injected into the top empty roadway in the goaf, and the strength of the high-water filling body is made equal to that of the upper coal seam; For goafs where no caving is carried out, gangue blocks of different particle size distributions are filled into the top goaf of the goaf, and the expansion coefficient of the gangue blocks after collapse is the same as that of the upper coal seam after collapse; S5: For each goaf in the lower coal seam, inject high-water-density material and water into the bottom goaf, and make the strength of the high-water-density filling body the same as that of the lower coal seam; S6: The fully mechanized caving technology is used to mine the fully mechanized caving working face; the goaf of the roadway filled with waste rock blocks is not mined; S7: Use the coal mining equipment used in the fully mechanized caving working face and adopt the fully mechanized caving technology to mine the lower coal seam, and the caving height is less than the height of the bottom empty road.

2. The method for fully mechanized top-coal caving and mining in a coal mine according to claim 1, characterized in that: In step S7, for each goaf in the lower coal seam, the volume ratio of the lower coal seam objects to be mined and other non-coal objects is calculated when the goaf is mined; mining is performed on the goaf whose volume ratio reaches the second threshold, and mining is not performed on the goaf that does not reach the second threshold.

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