A method for layered mining of thick coal seams with cemented backfilling in longwall.

Abstract

This invention discloses a method for longwall cemented backfilling mining of thick coal seams, comprising: dividing the thick coal seam into four layers according to a layer thickness of 1.8–4.0 m for downward mining, with the upper and lower layers sharing a preparation roadway excluding the cut-out; arranging equipment according to the cemented backfilling method of fully mechanized longwall mining, with the return airway arranged along the roof of the first layer and the transport airway arranged along the floor of the second layer; after the first layer has been backfilled and mined for 30 m, a cut-out for the second layer is arranged directly below the cut-out for the first layer; alternating mining, preparation, backfilling, and solidification of the first and second layers until the working face is completely mined; three months after the first and second layers have been mined, the third and fourth layers are mined using the same method until the entire thick coal seam is mined. This invention provides a method for backfilling mining of thick coal seams, which improves mining efficiency, reduces tunneling work, and lowers production costs through simultaneous layered mining, and has wide applicability in the mining of thick coal seams under "three-under" pressure.

Description

Technical Field

[0001] This invention relates to the field of mining technology for thick coal seams with three layers, and in particular to a method for mining longwall cemented backfill coal seams with a thickness of 3.6m to 16m in layers. Background Technology

[0002] Thick coal seams (>3.5m) are widely distributed in my country and are crucial for achieving high-yield and efficient mining. To meet the energy demands of rapid economic development, after nearly a decade of continuous high-intensity mining, most mining areas face the challenge of mining under pressure from the surrounding rock strata. Currently, there are two main categories of mining methods for these thick coal seams in China: the first is limited-thickness mining, strip mining, and coordinated mining; the second is layered mining and backfilling mining. Both methods can control surface subsidence to some extent, ensuring the safety of surface buildings, water bodies, railways, etc. However, the first method suffers from low recovery rates, significant coal loss, high production costs, low efficiency, and small scale; the second method has a higher recovery rate, but requires waiting for the backfill to solidify, resulting in only one shift of coal production per day, leading to low recovery efficiency, large tunneling workload, and difficulty in achieving high-yield and efficient production. Therefore, developing a mining method that can control rock strata movement, protect surface buildings and aquifers, and achieve high-yield, high-efficiency, and low-cost recovery of thick coal seams is urgently needed.

[0003] Chinese patent application CN103306720A discloses a method for inclined layered solid backfilling mining of extra-thick coal seams. This method determines the number of inclined layers based on a layer thickness of 2.5–4.5 m, employs a layered mining and downhill backfilling mining sequence, arranges roadways and equipment according to conventional solid backfilling mining methods, and implements a cyclical sequence of mining, laying metal mesh and bamboo mats, and backfilling to complete the first mining face and the backfilling mining of the first layer. Simultaneously, four months after the completion of mining in this layer, mining is carried out at the corresponding location of the second layer, under the artificial false roof formed by the first layer, using the same backfilling mining method. This cycle continues, continuously mining the current layer under the artificial false roof created by the previous layer, until the entire extra-thick coal seam is mined. However, this patent application uses solid backfilling downhill longwall mining with three layers of underburden, resulting in low production efficiency, a large amount of tunneling work, and difficulty in meeting high-yield and high-efficiency production requirements.

[0004] Chinese patent CN107939401B discloses a method for solid cemented backfilling roadway mining of extra-thick coal seams. This method divides the extra-thick coal seam in the section to be mined into multiple layers according to its height, and mines from top to bottom. Each layer is further divided into multiple segments according to the mining height and the length of the working face coal wall, and these segments are mined intermittently. Mining begins from the first segment of the first layer, proceeding along the uphill roadway direction from the boundary of the protective coal pillar. Roadway mining and cemented backfilling are carried out in a progressive, cyclical manner. Coal is extracted from the coal seam using a roadheader. Cementing material is injected into the mined roadway, flowing along the roadway to the other end until it fills the entire roadway. After solidification, the cementing material has excellent pressure-bearing capacity and deformation resistance. This method employs roadway mining, layered mining and backfilling to recover coal under pressure, resulting in low production efficiency, a large amount of tunneling work, and difficulty in meeting the requirements for high-yield and high-efficiency production.

[0005] Chinese patent CN107939401B discloses a method for layered intermittent backfilling mining of extra-thick coal seams. This method employs a downward mining sequence, first mining the backfilling layers sequentially from top to bottom: In each backfilling layer, a solid backfilling mining face is arranged, and metal mesh and bamboo mats are laid to create artificial false roofs and floors, compacting and backfilling the materials transported to the goaf; then, the caving layers are mined sequentially from top to bottom: the internal stress and deformation of the backfill in each backfilling layer are monitored, and after confirming the stability of the backfill deformation, a fully mechanized mining face is arranged in the caving layer for caving mining. This method uses both backfilling and caving methods to manage the roof, and employs layered mining and backfilling to recover coal under pressure from the "three underground" areas (underground, underground, and underground). However, it has low production efficiency, a large amount of tunneling work, and is difficult to meet the requirements of high-yield and high-efficiency production.

[0006] Chinese patent CN108278113B discloses a method for layered non-integral backfilling mining of extra-thick coal seams. This method utilizes upper pillar non-integral backfilling to recover coal pillars and lower strip backfilling mining. The entire coal seam is mined sequentially using these two methods, first the upper layer, then the lower layer, until the entire coal seam is mined. However, this method has low production efficiency and a large amount of tunneling work, making it difficult to meet the requirements of high-yield and high-efficiency production.

[0007] Chinese patent application CN104775817A discloses a full negative pressure continuous mining and step-by-step replacement "three-under" coal mining method. This method mainly divides the entire coal mining section into multiple production units, each consisting of three branch roadway working faces. The branch roadways connect the transport roadway and the return air roadway. The mining sequence adopts a skip-mining method, starting with unit one, then proceeding to unit one, unit three, unit five, and so on, then starting with unit two, then proceeding to unit two, unit four, unit six, and so on, until all production units in the entire section are mined and backfilled. It employs a shortwall mining method within the working face, mining thick coal seams in layers. However, this method has low production efficiency, requires a large amount of tunneling work, and is difficult to meet the needs of high-yield and high-efficiency production.

[0008] This invention provides a fully mechanized longwall mining method for thick coal seams, which combines layered mining and cemented backfilling. The method employs fully mechanized longwall mining, resulting in high recovery and backfilling efficiency. The use of backfilling significantly improves resource recovery rate. Backfilling and mining can be carried out in parallel, theoretically increasing efficiency by more than 100%. Summary of the Invention

[0009] In view of this, the purpose of this invention is to propose a method for mining thick coal seams by layering and simultaneously mining longwall cemented backfilling, which can achieve large-scale mining with high mining efficiency, small tunneling workload and low production cost.

[0010] Based on the above objectives, the present invention provides a method for layered mining and longwall cemented backfilling of thick coal seams, comprising the following steps:

[0011] Based on the thickness of the thick coal seam, the overburden structure, and the protection requirements for surface structures and aquifers, coal seams with a thickness of 3.6m to 16m are divided into 2 or 4 layers with a thickness of 1.8m to 4.0m per layer.

[0012] The working face is laid out according to the cemented backfilling method of integrated mechanized longwall mining. The working face is 100m to 200m long and the mining roadway is 4m to 6m wide. The return airway is arranged along the roof of the first layer and the transport roadway is arranged along the floor of the second layer. The first and second working faces share the transport roadway, the return airway and other preparation roadways except for the cut-in, such as the reverse chamber, the centralized transport roadway, and the stone gate.

[0013] The first layer of working face is subjected to mining and filling cycle operation, which includes mining, preparation, filling and solidification processes in sequence; the cycle operation is repeated until the first layer advances to a position 30-40m away from the cut-off point, the first layer of transport roadway and return airway are reinforced with support, and roadway retention along the goaf is achieved;

[0014] The second working face is arranged directly below the first working face, and the second working face is used for mining and filling cycle operation. The second working face lags behind the first working face by 30-40m. The mining and filling cycle of the first and second working faces is alternating. Ventilation windows are set in the goaf section of the first transport roadway to adjust the air volume.

[0015] Repeat the mining and filling cycle until the first and second working faces are completely mined out.

[0016] Three months after the completion of the second working face, the third and fourth working faces are arranged 20-30m below it, perpendicular to the inclination and advancing direction of the second working face. The working faces are then mined in an alternating mining and filling cycle according to the first and second working faces until the entire "three-under" thick coal seam is mined.

[0017] In some embodiments, the mining and filling operation cycle of the first and second working faces is alternating, which means that the first and second working faces take turns performing coal mining, preparation, filling and solidification processes in sequence.

[0018] In some implementations, during the mining and filling cycle of the first working face, return airway and transport airway are left along the goaf and are supported in advance.

[0019] In some implementations, during the second layer filling process, the sealed space formed by the filling bag or flexible mold extends to the return air level and the transport level, filling both levels.

[0020] In some implementations, a layered, simultaneous, downward mining sequence is adopted.

[0021] In some embodiments, coal mining refers to cutting coal, moving the tube sheet conveyor, and moving the filling hydraulic support, repeating this cycle until one filling step is advanced, with the filling step ranging from 2.4 to 6.4 meters; preparation refers to hanging filling bags or flexible molds in the goaf under the protection of the rear tail beam of the support to form a sealed space, laying filling pipelines, and installing relevant pipe fittings; cemented filling refers to transporting the slurry prepared on the ground through pipelines to the sealed space formed by the filling bags or flexible molds by pump pressure and gravity until the sealed space is filled; solidification refers to solidification after 6 to 10 hours to achieve self-supporting and initial strength.

[0022] As can be seen from the above, the thick coal seam layered mining and longwall cemented backfilling method provided by the present invention, through the layered mining roadway arrangement, allows the upper and lower working faces to share all the preparatory roadways except for the cut-in, reducing the amount of mine roadway engineering and saving construction time and costs. Furthermore, by adopting the staggered advance of the upper and lower layered working faces and the staggered arrangement of the upper and lower layers, the stress concentration of the surrounding rock in the roadway is reduced, and the difficulty of roadway support is reduced. At the same time, the alternating cyclic operation of the upper and lower layered working faces increases the working face output and improves labor efficiency.

[0023] The coal mining method provided by this invention can not only effectively control rock strata movement, protect surface buildings and aquifers, and improve the recovery rate of thick coal seams under pressure, but also significantly improve the efficiency of backfilling mining and reduce its cost, thus having wide applicability in this technical field. Furthermore, this invention consumes solid waste such as coal gangue, construction waste, and fly ash, resulting in significant environmental, economic, and social benefits. Attached Figure Description

[0024] Figure 1 A schematic diagram of the working face layout structure in an embodiment of the thick coal seam layered mining and longwall cemented backfilling method provided by the present invention;

[0025] Figure 2 This is a cross-sectional view along direction AA in the schematic diagram of the working face layout structure in an embodiment of the thick coal seam layered mining and longwall cemented backfilling method provided by the present invention.

[0026] In the diagram: 1-Return airway shared by the first and second working faces; 2-Transportation airway shared by the first and second working faces; 3-First working face; 4-Second working face; 5-Filling trunk pipeline; 6-Working face filling pipeline; 7-Working face material placing pipe; 8-Filling bag; 9-Filling body; 10-Filling hydraulic support; 11-Support tail beam; 12-End support; 13-Coal mining machine; 14-Scraper conveyor; 15-Crusher; 16-Transfer conveyor; 17-Belt conveyor; 18-Single support. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0028] It should be noted that all uses of "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two entities or parameters with the same name but different names. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the present invention. Subsequent embodiments will not explain this in detail.

[0029] See attached document Figure 1 and attached Figure 2 These are, respectively, a schematic diagram of the working face layout structure and a cross-sectional view along the AA direction in the schematic diagram of the working face layout structure in an embodiment of the thick coal seam layered co-mining longwall cemented backfilling coal mining method provided by the present invention.

[0030] An embodiment of the thick coal seam layered longwall cemented backfilling mining method provided by the present invention includes the following steps:

[0031] Step 101: Based on the thickness of the thick coal seam, the overburden structure, and the protection requirements for surface structures and aquifers, the thick coal seam is divided into 4 layers with a thickness of 1.8m to 3.0m per layer;

[0032] Step 102: Arrange the equipment according to the conventional cemented backfilling coal mining method. The return airway 1 is arranged along the roof of the first layer, and the transport airway 2 is arranged along the floor of the second layer. The first layer working face 3 and the second layer working face 4 share the return airway, the transport airway, and other mining preparation roadways except for the cut-off.

[0033] Step 103: Perform the first layer working face 3 mining and filling cycle operation, which includes sequentially performing coal mining, preparation, filling and solidification processes; repeat the cycle operation until the first layer advances to a position 30m away from the cut-off point;

[0034] Step 104: Arrange the second layer working face 4 directly below the first layer cutting face, and carry out the second layer working face 4 mining and filling cycle operation. The second layer working face 4 lags behind the first layer working face 3 by 30-40m; the mining and filling cycle of the first layer working face 3 and the second layer working face 4 is alternating.

[0035] Step 105: Repeat the mining and filling cycle until the first working face 3 and the second working face 4 are mined out.

[0036] Step 106: Three months after the completion of the second layer working face 4, the third layer working face and the fourth layer working face are arranged directly below it, perpendicular to the advancing direction of the second layer working face 4, and offset by 20-30m. The mining is carried out in the alternating mining and filling cycle operation mode of the first layer and the second layer until the mining of the entire "three-under" thick coal seam is completed.

[0037] Preferably, the mining and filling operation cycle of the first layer working face 3 and the second layer working face 4 is alternating, which means that the first layer working face 3 and the second layer working face 4 take turns to carry out the coal mining, preparation, filling and solidification processes in sequence.

[0038] Furthermore, during the 3-stage working face mining and filling cycle operation, a transport and return airway is left along the goaf, and advanced support is provided for it.

[0039] Preferably, during the second layer filling process, the sealed space formed by the filling bag 8 or the flexible mold extends to the transport and return air level, filling both level.

[0040] Optionally, a layered, simultaneous downward mining sequence can be adopted.

[0041] Furthermore, the coal mining refers to the coal cutting by the coal mining machine 13, the pushing of the tube sheet conveyor 14, and the pushing of the filling coal mining hydraulic support 10, in a cycle until one filling step is advanced, with the filling step ranging from 2.4 to 6.4 meters; the preparation refers to hanging filling bags 8 or flexible molds in the goaf under the protection of the tail beam 11 of the support to form a sealed space, laying filling pipelines and installing relevant pipe fittings; the cemented filling refers to transporting the slurry prepared on the ground through pipelines to the sealed space formed by the filling bags or flexible molds by pump pressure and gravity until the sealed space is filled; the solidification refers to solidification after 6 to 10 hours to achieve self-supporting and initial strength.

[0042] Specifically, refer to the appendix Figure 1 and attached Figure 2Another embodiment of the thick coal seam layered mining and longwall cemented backfilling method provided by the present invention includes the following steps:

[0043] Step 201: Based on the coal seam thickness of 10m, the medium-hard overburden structure and the aquifer protection requirements, the thick coal seam is divided into 4 layers at 2.5m intervals. The four working faces from top to bottom are the first layer, the second layer, the third layer and the fourth layer working faces. The mining sequence of unified tunneling and separate mining is adopted.

[0044] Step 202: The first layer working face 3 and the second layer working face 4 share the transport and return air level; the return air level 1 is arranged along the top plate of the first layer working face for personnel, material, and air intake; the transport level 2 is arranged along the bottom plate of the second layer working face for return air and coal transport; fully mechanized cemented filling equipment and materials are arranged in the transport, return air level and other working face shafts and chambers.

[0045] Step 203: Conduct the first layer working face 3 filling and coal mining cycle operation, that is, carry out coal mining, preparation, filling and solidification processes in sequence; coal mining is carried out by the coal mining machine 13 cutting coal, pushing the tube sheet conveyor 14, pushing the filling coal mining hydraulic support 10 and the end support 12 in sequence, and the coal from the working face is transported out by the crusher 15, the transfer machine 16 and the belt conveyor 17. This cycle is repeated until one filling step distance (e.g., 3.2m) is advanced; then filling preparation is carried out, that is, laying the filling main pipeline 5, the working face filling pipeline 6, the working face material distribution pipe 7 and installing the relevant pipe fittings, at the tail beam 1 of the support. 1. Under protection, filling bags 8 are hung in the goaf to form a sealed space; after preparation, cemented filling is carried out. The slurry made by mixing river sand, fly ash, cementing materials, additives, etc. with water is transported through pipelines to the sealed space formed by filling bags 8 by pump pressure and gravity until the sealed space is filled; solidification, that is, solidification for 6 to 10 hours to form a pressure-bearing filling body 9; the next mining and filling cycle is carried out until the first layer advances to a position 30m away from the cut-off; during the mining and filling cycle of the first layer working face, a transport and return air level is left along the goaf, and it is supported by single props 18;

[0046] Step 204: Arrange the second layer working face 4 cutter directly below the first layer working face 3 cutter. Perform the mining and filling cycle operation of the second layer working face 4 according to the method described in step 203 to advance the working face. The horizontal distance between the two working faces is 30-40m. During the filling process of the second layer working face 4, the sealed space formed by the filling bag needs to extend to the two roadways to fill them. The operation cycle of the two working faces is alternating, that is, when the first layer working face 3 is cutting coal, the filling body of the second layer working face 4 is solidifying and waiting; when the first layer working face 3 is preparing and filling, the second layer working face 4 is cutting coal; when the filling body of the first layer working face 3 is solidifying and waiting, the second layer working face 4 is preparing and filling. This cyclic operation method requires workers to have high labor skills and be proficient in various filling and coal mining techniques. This cyclic operation method ensures continuous production of the working face and improves the output and production efficiency of the working face.

[0047] Step 205: Repeat the mining and filling cycle until both the first and second working faces have been mined out;

[0048] Step 206: Three months after the completion of the second working face 4, the third and fourth working faces are arranged 30m directly below it, perpendicular to the direction of the working face advance. The working faces are mined using the same methods as the first and second working faces, such as mining and filling cycles and alternating operations, until the entire "three-under" thick coal seam is mined.

[0049] As can be seen from the above, the thick coal seam layered mining and longwall cemented backfilling method provided by the present invention, through the layered mining roadway arrangement, allows the upper and lower working faces to share all the preparatory roadways except for the cut-in, reducing the amount of mine roadway engineering and saving construction time and costs. Furthermore, by adopting the staggered advance of the upper and lower layered working faces and the staggered arrangement of the upper and lower layers, the stress concentration of the surrounding rock in the roadway is reduced, and the difficulty of roadway support is reduced. At the same time, the alternating cyclic operation of the upper and lower layered working faces increases the working face output and improves labor efficiency.

[0050] The coal mining method provided by this invention can not only effectively control rock strata movement, protect surface buildings and aquifers, and improve the recovery rate of thick coal seams under pressure, but also significantly improve the efficiency of backfilling mining and reduce its cost, thus having wide applicability in this technical field. Furthermore, this invention consumes solid waste such as coal gangue, construction waste, and fly ash, resulting in significant environmental, economic, and social benefits.

[0051] The upper and lower limits of the process parameters (such as temperature, time, etc.) and the range values ​​of the present invention can all achieve the method, and examples are not listed here.

[0052] All aspects not described in detail in this invention can be covered using conventional technical knowledge in the field.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A longwall cemented fill mining method for the simultaneous slicing of thick coal seams, characterized in that, The method comprises the following steps: According to the thickness of the thick coal seam, the overburden structure, and the requirements of the surface buildings and the aquifer protection, the thick coal seam with a thickness of 3.6m-16m is divided into two or four sub-layers according to the thickness of each layer of 1.8m-4.0m; The working face length is 100m-200m, the recovery roadway width is 4m-6m, the air return roadway is arranged along the roof of the first sub-layer, the transportation roadway is arranged along the floor of the second sub-layer, the first sub-layer working face and the second sub-layer working face share the transportation roadway, the air return roadway and other mining and preparation roadways except the cut; The first sub-layer working face performs the mining and filling cycle operation, which comprises sequentially performing the mining, preparation, filling and solidification processes; the cycle operation is repeated until the first sub-layer advances to a position 30-40m away from the cut, the first sub-layer transportation roadway and the air return roadway are reinforced, and the gob-side entry retaining is realized; The second sub-layer working face cut is arranged directly below the first sub-layer cut, the second sub-layer working face performs the mining and filling cycle operation, and the second sub-layer working face lags behind the first sub-layer working face by 30-40m; the first sub-layer working face and the second sub-layer working face perform the mining and filling cycle operation in an alternating manner, and the air window is arranged in the gob-side entry retaining section of the first sub-layer transportation roadway to adjust the air volume; The mining and filling cycle operation is repeated until the first sub-layer working face and the second sub-layer working face are mined completely; After three months from the completion of the mining of the second sub-layer working face, the third sub-layer working face and the fourth sub-layer working face are arranged below the second sub-layer working face and offset by 20-30m in the direction perpendicular to the inclination direction and the advancing direction of the second sub-layer working face, the mining is performed in the alternating mining and filling cycle operation manner of the first sub-layer and the second sub-layer, and the entire thick coal seam mining is completed.

2. The longwall cemented fill mining method of slicing the thick coal seam simultaneously, according to claim 1, characterized in that, The first sub-layer working face and the second sub-layer working face perform the mining and filling cycle operation in an alternating manner, which means that the first sub-layer working face and the second sub-layer working face alternately perform the mining, preparation, filling and solidification processes, the second sub-layer performs the filling and solidification when the first sub-layer performs the mining, and one sub-layer always mines.

3. The longwall cemented fill mining method of thick coal seams in slices simultaneously, according to claim 1, characterized in that, The thick coal seam adopts the downward sub-layer simultaneous mining, the first sub-layer working face and the second sub-layer working face share the recovery roadway and other mining and preparation roadways except the cut.

4. The longwall cemented fill mining method of thick coal seams in slices simultaneously, according to claim 1, characterized in that, During the mining and filling cycle operation of the first sub-layer working face, the transportation roadway and the air return roadway are retained along the goaf, and the advanced support is performed.

5. The longwall cemented fill mining method of thick coal seams in slices simultaneously, according to claim 1, characterized in that, During the filling of the second sub-layer, the sealing space formed by the filling bag or the flexible mold extends to the transportation roadway and the air return roadway, and the transportation roadway and the air return roadway are filled.

6. The longwall cemented fill mining method of thick coal seams in slices simultaneously, according to claim 1, characterized in that After three months from the completion of the mining of the second sub-layer working face, the third sub-layer working face is arranged below the second sub-layer working face, and the third sub-layer working face is offset by 20-30m in the working face inclination direction and by 20-30m in the strike direction from the second sub-layer working face.

7. The longwall cemented fill mining method with slicing of thick coal seams according to any of claims 1 - 6, characterized in that, The coal mining refers to cutting coal, pushing and scraping a conveyor, pushing and filling a hydraulic support, and the cycle is repeated until a filling step is pushed, and the filling step range is 2.4-6.4 m; the preparation refers to hanging a filling bag or a flexible membrane under the protection of a tail beam of a support in a goaf to form a sealed space, laying a filling pipeline and installing related pipe fittings; the cemented filling refers to pumping and filling a cementing agent prepared on the ground into the sealed space formed by the filling bag or the flexible membrane through a pipeline by means of pump pressure and gravity until the sealed space is filled; and the solidification refers to solidifying for 6-10 h to achieve self-standing and initial strength.

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