Fully-mechanized caving re-mining method for stepping-out area of coal mine

Abstract

The invention belongs to the field of coal mining methods, and particularly relates to a coal mine stepping area fully-mechanized caving re-mining method which comprises the steps that an upper coal seam and a middle coal seam are mined together through a fully-mechanized caving process, the middle coal seam is mined, the upper coal seam is mined, and a mining roadway is arranged in the middle coal seam to arrange a standard fully-mechanized caving face; meanwhile, a filling process is determined according to the volume ratio of the caved and mined coal, high-water materials are adopted for filling the roadway goaf which is caved and mined due to the high volume ratio of the coal, the strength of a filling body is guaranteed, and gangue blocks are adopted for filling the roadway goaf which is caved and mined due to the low volume ratio of the coal; in addition, all the roadway goaf of the lower coal seam is filled with high-water materials. The mining process of the upper coal seam can be simplified, the roadway tunneling workload is reduced, meanwhile, a standard working face can be arranged, the stoping efficiency is improved, the stoping cost is reduced, and the coal seam re-mining and stoping problems affected by the roadway goaf are solved.

Description

Technical Field

[0001] The present invention belongs to the field of coal mining methods, and particularly relates to a fully mechanized top coal caving recovery method for a mined-out area in a coal mine. Background Art

[0002] The small coal mines are irregularly mined, generally adopting the roadway mining method, that is, mining the coal seam in a form similar to digging a tunnel in the coal seam. This mining method can simplify the support process or even not carry out support, saving the support cost and the cost of mining equipment. However, this mining method has low efficiency, low recovery rate, and poor safety; after the small coal mines are mined, mined-out areas including gob roads 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 planning will be regularly recovered later, such as by using the fully mechanized coal mining process. However, the formed mined-out areas of roadways will affect the subsequent mining process and mining plan. For example, if the mined-out area of the roadway is located above the coal seam to be mined and is relatively close, roof caving accidents are likely to occur during the mining of the coal seam to be mined; if the mined-out area of the roadway is located below the coal seam to be mined and is relatively close, a situation of mined-out area caving mining is formed, and floor subsidence accidents are likely to occur during the mining of the coal seam to be mined; if the coal seam where the mined-out area of the roadway is located is the coal seam to be mined, it is necessary to consider the ability of the coal pillar in the mined-out area of the roadway to bear the advanced support pressure, and the stability of the roof when the coal pillar in the mined-out area of the roadway is recovered by the fully mechanized top coal caving process.

[0004] If the intact coal seam to be mined is a middle coal seam, and the upper and lower coal seams adjacent to it have been mined by small coal mines and there are mined-out areas of roadways, for this complex mining condition, how to plan the mining sequence of the coal seam and how to pass through the mined-out area of the roadway during the coal seam mining, and ensure mining safety and mining benefits have become technical difficulties to be overcome. Summary of the Invention

[0005] In view of the above technical problems, the present invention provides a fully mechanized top coal caving recovery method for a mined-out area in a coal mine, including the following steps: S1: Drive a coal haulage roadway and a material haulage roadway along the strike in the middle coal seam, and drive a cutting roadway to connect the coal haulage roadway and the material haulage roadway to form a fully mechanized top coal caving face; S2: Determine the mining height and caving height of the fully mechanized top coal caving face. The mining height part is the middle coal seam and part of the parting layer, and the caving height part is part of the parting layer and the upper coal seam; S3: For each mined-out area of the roadway in the upper coal seam, assume caving mining, and calculate the volume ratio of the caved objects in the upper coal seam to other non-coal objects; for the mined-out area of the roadway with the volume ratio reaching the first threshold, carry out caving mining, and for the mined-out area of the roadway that does not reach the first threshold, do not carry out caving mining, and only mine the mining height part; carry out caving mining on the area of the upper coal seam without mined-out areas of the roadway; S4: For the roadway gob area where coal mining with top coal caving is carried out, inject high-water material and water into the top empty roadway in this roadway gob area, and make the strength of the high-water filling body the same as that of the upper coal seam. For the roadway gob area where coal mining with top coal caving is not carried out, fill different particle size graded gangue blocks into the top empty roadway in this roadway gob area, and make the bulking factor of the gangue blocks after caving the same as that of the upper coal seam after caving. S5: For each roadway gob area in the lower coal seam, inject high-water material and water into the bottom empty roadway therein, and make the strength of the high-water filling body the same as that of the lower coal seam. S6: Adopt the fully mechanized top coal caving technology for mining the fully mechanized caving face; the roadway gob area filled with gangue blocks does not carry out coal mining with top coal caving.

[0006] Preferably, it further includes S7: Adopt the fully mechanized one-trip full-height mining technology for mining the lower coal seam. Or, use the coal mining equipment used in the fully mechanized caving face, and adopt the fully mechanized caving technology for mining the lower coal seam, and the caving height is greater than the height of the bottom empty roadway.

[0007] Preferably, in step S7, when adopting the fully mechanized caving technology, for each roadway gob area in the lower coal seam, assume coal mining with top coal caving is carried out, and calculate the volume ratio of the coal mining object in the lower coal seam to other non-coal objects; for the roadway gob area where the volume ratio reaches the second threshold, carry out coal mining with top coal caving, and for the roadway gob area that does not reach the second threshold, do not carry out coal mining with top coal caving.

[0008] The beneficial effects of the present invention are as follows: 1. The present invention aims at the working conditions of extremely close coal seam groups, where there is a roadway gob area in the upper coal seam, the middle coal seam is intact, and there is a roadway gob area in the lower coal seam. The upper coal seam and the middle coal seam are mined together by the fully mechanized caving technology, in which the middle coal seam is mined and the upper coal seam is mined with top coal caving; the return airway is arranged in the middle coal seam, and a standard fully mechanized caving face can be arranged by using the middle coal seam; for the roadway gob area with a high recovery rate, there is no need to carry out coal mining with top coal caving, and for the roadway gob area with a low recovery rate, coal mining with top coal caving is carried out. Compared with separately arranging a fully mechanized coal mining face for mining the upper coal seam, the mining process of the upper coal seam can be simplified, and the roadway driving workload can be reduced.

[0009] 2. Further, different filling processes are adopted for the upper coal seam roadway gob area according to whether coal mining with top coal caving is carried out; for the roadway gob area where coal mining with top coal caving is carried out, due to the addition of the coal mining with top coal caving process, the mining speed of the fully mechanized caving face is slow, and the roof needs to maintain a relatively long-term strength. Therefore, high-water material is used for filling to ensure the strength of the filling body; while for the roadway gob area where coal mining with top coal caving is not carried out, gangue blocks are used for filling. Since the gangue blocks can be obtained locally and do not require cementation, the cost is low, and since coal mining with top coal caving is not carried out, the advancing speed of the fully mechanized caving face is fast, and the requirement for the roof strength is reduced, and gangue blocks with low strength can be used for filling; in addition, using gangue blocks for filling can make the bulking factor after caving the same as that of the upper coal seam, ensuring the smoothness of the roof subsidence.

[0010] 3. For all the roadway gob areas in the lower coal seam, high-water materials are used for backfilling to ensure the strength of the backfill body, which is conducive to ensuring the stability of the floor during the mining of the middle coal seam. At the same time, due to the proximity of the gob areas formed after the mining of the upper coal seam and the middle coal seam to the lower coal seam, the high-water backfill body can ensure that there is a rock stratum with sufficient thickness and strength to isolate the lower coal seam from the upper gob area, reducing the risk of roof fall during the mining of the lower coal seam. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic diagram of the strata structure of the gob area of the coal mine of the present invention; Figure 2 is a schematic plan view of the layout of the gateway roadways in the fully mechanized caving face of the present invention; Figure 3 is a schematic plan view of the relative position relationship between the gob area of the 9# coal roadway and the gateway roadways in the fully mechanized caving face of the present invention; Figure 4 is a schematic plan view of the relative position relationship between the gob area of the 11# coal roadway and the gateway roadways in the fully mechanized caving face of the present invention; In the figure, limestone roof 1; 9# coal 2; shale parting layer 3; 10# coal 4; shale floor 5; 11# coal 6; coal haulage gateway 7; cutting roadway 8; material haulage gateway 9; coal haulage rise 10; material haulage rise 11; top gob roadway 12; top coal pillar 13; bottom gob roadway 14; bottom coal pillar 15; fully mechanized caving face 16. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0012] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0013] As Figure 1 、 Figures 3 - 4As shown in the figure, there are three coal seams in the third panel of Liuwan Coal Mine of Fenxi Mining Group, namely Coal Seam 9#2, Coal Seam 10#4, and Coal Seam 11#6. The thicknesses are 1.5m, 1.85m, and 4.9m respectively. They are all nearly horizontal coal seams with an inclination angle of about 4°. The upper part of Coal Seam 9#2 is the limestone roof 1 with a thickness of 5.0m. Between Coal Seam 9#2 and Coal Seam 10#4 is the shale parting layer 3 with a thickness of 2.15m. Between Coal Seam 10#4 and Coal Seam 11#6 is the shale floor 5 with a thickness of 4.4m. In some areas of Coal Seam 9#2 and Coal Seam 11#6, the roadway mining process has been used by small coal mines, forming roadway gob areas. The roadway gob area in Coal Seam 9#2 includes the top gob roadway 12 and the top coal pillar 13. The roadway gob area in Coal Seam 11#6 includes the bottom gob roadway 14 and the bottom coal pillar 15. Coal Seam 10#4 is an intact unmined coal seam. The top gob roadway 12 is 1.5m high and 2.2m wide. The bottom gob roadway 14 is 1.8m high and 2.2m wide. The bottom gob roadway 14 is excavated along the top surface of Coal Seam 11#6. The unexcavated part of Coal Seam 11#6 is below the bottom gob roadway 14. According to the thicknesses of Coal Seam 9#2, Coal Seam 10#4, and Coal Seam 11#6, the thicknesses and strengths of the roof and floor rock layers, and the thickness and strength of the parting layer, combined with the scope of the roadway gob area, the following mining method is proposed below. On the premise of ensuring safe mining, the mining efficiency and mining benefits can be maximized.

[0014] Specifically, the present invention proposes a fully mechanized top coal caving mining method for coal mine gob areas. Among them, fully mechanized top coal caving refers to the fully mechanized top coal caving mining process, which is a well-known mining method in the coal mine field. Re-mining refers to the re-mining of the unmined part of the coal seam that has already been mined due to incomplete mining, which is a well-known technical term in this field. Gob area refers to the mined-out area existing below the coal mining face, which is a well-known technical term in this field. For example, in this embodiment, there is a roadway gob area of Coal Seam 11#6 below the fully mechanized coal mining face 16. For the fully mechanized coal mining face 16, the roadway gob area of Coal Seam 11#6 is the gob area. The fully mechanized top coal caving mining method for coal mine gob areas includes the following steps: S1: As Figures 2 - 4 shown in the figure, in Coal Seam 10#4, the coal haulage roadway 7 is driven along the strike from the coal haulage rise 10, and the material haulage roadway 9 is driven along the strike from the material haulage rise 11. The cutting eye 8 is driven to connect the coal haulage roadway 7 and the material haulage roadway 9 to form the fully mechanized coal mining face 16. The fully mechanized coal mining face 16 is 800m long along the strike and 204m long along the dip. Based on Coal Seam 10#4, the average buried depth of the fully mechanized coal mining face 16 is 114.8m. Strike and dip are well-known technical terms in the field of geological engineering and will not be explained here. S2: Determine the mining height and caving height of the fully mechanized coal mining face 16. The fully mechanized coal mining face 16 is mined by the fully mechanized top coal caving process. The designed mining height is 2.35m, including the height of the entire Coal Seam 10#4 and 0.5m of the height below the shale parting layer 3. The designed caving height is 3.15m, including 1.65m of the height above the shale parting layer 3 and the height of the entire Coal Seam 9#2. S3: For each roadway gob area in the 9# coal seam 2, assuming caving mining is carried out, determine the mined volume of the top-level empty roadway 12 in the roadway gob area according to the height, width and total length of the top-level empty roadway 12. Further, according to the plane area of the roadway gob area, combined with the heights of the 9# coal seam 2, the shale parting layer 3, and the 10# coal seam 4, as well as the designed mining height and caving height, calculate the volume ratio of the 9# coal seam 2 and other non-coal objects (shale parting layer 3 and high-water filling body) caved out from the roadway gob area; conduct caving mining on the roadway gob areas where the volume ratio reaches the first threshold, and do not conduct caving mining on the roadway gob areas that do not reach the first threshold, but only mine the 2.35 m part of the designed mining height; conduct caving mining on other areas of the 9# coal seam 2 where there is no roadway gob area. The range of the first threshold is 0.3 - 0.4; S4: For the roadway gob areas where caving mining is carried out, inject high-water materials and water into the top-level empty roadway 12 in the roadway gob area, and adjust the strength of the formed high-water filling body by adjusting the ratio of the high-water materials to water, so that the strength of the high-water filling body is the same as that of the 9# coal seam 2; For the roadway gob areas where only the designed mining height part is mined without caving mining, fill different particle size graded gangue blocks into the top-level empty roadway 12 in the roadway gob area, and make the bulking factor of the gangue blocks the same as that of the 9# coal seam 2 after caving by adjusting the particle size and its gradation of the gangue blocks; the strength of the coal is low and the bulking factor is small, while the strength of the gangue blocks is high and the bulking factor is large, but there are voids between the gangue blocks, so by adjusting the particle size and its gradation of the gangue blocks, the same bulking factor as that of the 9# coal seam 2 can be achieved after caving; S5: For each roadway gob area in the 11# coal seam 6, inject high-water materials and water into the bottom-level empty roadway 14 therein, and adjust the strength of the formed high-water filling body by adjusting the ratio of the high-water materials to water, so that the strength of the high-water filling body is the same as that of the 11# coal seam 6; S6: Adopt the fully mechanized caving mining technology for the fully mechanized caving face 16, with a mining height of 2.35 m and a caving height of 3.15 m; do not conduct caving mining on the roadway gob areas filled with gangue blocks, but only mine the 2.35 m part of the designed mining height.

[0015] Further, a fully mechanized caving mining method for gob areas in a coal mine of the present invention further includes the step of mining the 11# coal seam 6 in the gob area, specifically: S7: Design a mining face in the 11# coal seam 6 and adopt the fully mechanized one-trip full-height mining technology for mining, with a mining height of 4.9 m; Alternatively, using the coal mining equipment employed in the fully mechanized top coal caving face 16, mining is carried out using the fully mechanized top coal caving technology, with a mining height of 2.5 m and a caving height of 2.4 m, and the caving height is greater than the height of the underlying gob roadway 14; for each gob area of the roadway in the 11# coal seam 6, assuming caving mining is carried out, calculate the volume ratio of the 16# coal seam 6 mined by caving to other non-coal objects (high water filling body); if this volume ratio reaches the second threshold, caving mining is carried out for this gob area of the roadway, if it does not reach the second threshold, caving mining is not carried out for this gob area of the roadway, and only the 2.5 m part of the designed mining height is mined; the 16# coal seam 6 area without a gob area of the roadway is subjected to caving mining; in this embodiment, the range of the second threshold is 0.4 - 0.5.

[0016] Of course, the above description is only a preferred embodiment of the present invention, and the present invention is not limited to listing the above embodiments. It should be noted that all equivalent substitutions and obvious deformation forms made by any person skilled in the art under the guidance of this specification fall within the substantial scope of this specification and should be protected by the present invention.

Claims

1. A fully-mechanized caving mining method for gob areas in coal mines, characterized in that, It includes the following steps: S1: Drive the coal haulage gateway and the material haulage gateway along the strike in the middle coal seam, and drive the cutting roadway to connect the coal haulage gateway and the material haulage gateway to form a fully mechanized top coal caving face; S2: Determine the mining height and caving height of the fully mechanized top coal caving face. The mining height part is the middle coal seam and part of the parting seam, and the caving height part is part of the parting seam and the upper coal seam; S3: For each roadway gob area in the upper coal seam, if caving mining is carried out, calculate the volume ratio of the caved upper coal seam objects to other non-coal objects; carry out caving mining on the roadway gob area where the volume ratio reaches the first threshold, and do not carry out caving mining on the roadway gob area that does not reach the first threshold, and only mine the mining height part; carry out caving mining on the upper coal seam area without roadway gob area; S4: For the roadway gob area where caving mining is carried out, inject high-water material and water into the top-level empty roadway in the roadway gob area, and make the strength of the high-water filling body the same as that of the upper coal seam; For the roadway gob area where caving mining is not carried out, fill the top-level empty roadway in the roadway gob area with gangue blocks of different particle size gradations, and make the bulking factor of the gangue blocks after collapse the same as that of the upper coal seam after collapse; S6: For each roadway gob area in the lower coal seam, inject high-water material and water into the bottom-level empty roadway in it, and make the strength of the high-water filling body the same as that of the lower coal seam; S7: Mine the fully mechanized top coal caving face by the fully mechanized top coal caving technology; do not carry out caving mining on the roadway gob area filled with gangue blocks; S8: Use the coal mining equipment used in the fully mechanized top coal caving face to mine the lower coal seam by the fully mechanized top coal caving technology, and the caving height is less than the height of the bottom-level empty roadway.

2. The fully-mechanized caving mining method for gob areas in coal mines according to claim 1, characterized in that, In step S8, for each roadway gob area in the lower coal seam, calculate the volume ratio of the caved lower coal seam objects to other non-coal objects when caving mining is carried out on the roadway gob area; carry out caving mining on the roadway gob area where the volume ratio reaches the second threshold, and do not carry out caving mining on the roadway gob area that does not reach the second threshold.

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