Layered interval paste filling coal mining method for three-under-three thick coal seam

Abstract

The embodiment of the invention discloses a layered interval paste filling coal mining method for a'under three 'thick coal seam, and relates to the technical field of coal filling mining, the coal mining method comprises the following steps: dividing a thick coal seam to be mined into at least two mining layers along the vertical direction; the thickness of the thick coal seam is greater than 3.5 m; all the layers are mined from top to bottom in sequence; wherein a transportation crossheading, an air return crossheading and an open-off cut of each layer are tunneled and arranged, each mining layer is divided into a plurality of branch roadways, the branch roadways are mined by adopting a coal mining method of branch roadway jump mining and paste filling, and filling mining of a lower layer is carried out after a working face of the upper layer is completely mined and a filling body reaches expected strength to form an artificial roof. The embodiment of the invention is suitable for mining the thick coal seam with the thickness of more than 3.5 m.

Description

Technical Field

[0001] The invention relates to the technical field of coal filling mining, and in particular to a "three-down" thick coal seam layered interval paste filling coal mining method. Background Art

[0002] The thickness of underground coal seams is generally classified into: thin coal seams, medium-thick coal seams, thick coal seams and extra-thick coal seams. Among them, the thickness of thin coal seams is generally less than or equal to 1.3 meters; the thickness of medium-thick coal seams is generally between 1.3 meters and 3.5 meters; the thickness of thick coal seams is generally greater than 3.5 meters; the thickness of extra-thick coal seams refers to coal seams with a thickness of more than 8 meters. "Three-under" coal mining refers to the mining of deposits located under buildings, railways and water bodies. Faced with the rapid development of the coal industry, more and more coal companies are facing the mining difficulties of "three-under" thick coal seams and extra-thick coal seams. According to relevant technical regulations of the coal industry, the resource recovery rate of thick coal seam mining is ≥ 75%, and based on the occurrence conditions of extra-thick coal seams and belonging to "three-under" overburden resources, its recovery rate is bound to be lower than 75%, resulting in a large amount of coal resources Waste, at the same time, a large amount of corner coal and irregular block coal resources are left behind during the mining of extra-thick coal seams. Therefore, exploring new mining methods for "three-under" thick coal seams and extra-thick coal seams has become a technical problem that needs to be solved urgently. Summary of the invention

[0003] In view of this, an embodiment of the present invention provides a "three-down" thick coal seam layered interval paste filling coal mining method, which can not only effectively support the roof, but also improve the resource extraction rate.

[0004] In order to achieve the above object, the present invention adopts the following technical scheme: A "three-down" thick coal seam stratified and spaced paste filling coal mining method comprises: dividing the thick coal seam to be mined into at least two mining layers along the vertical direction; the thickness of the thick coal seam is greater than 3.5 meters; mining each layer in sequence from top to bottom; wherein each layer is excavated and arranged with its own transport drift, return air drift and cutting eye, each mining layer is divided into a plurality of branch tunnels, and the branch tunnels are mined by a branch tunnel skipping and then paste filling coal mining method, and after the upper layer working face is fully mined and the filling body reaches the expected strength to form an artificial false roof, the filling mining of the lower layer is then carried out.

[0005] According to an implementable manner of an embodiment of the present invention, dividing the thick coal seam to be mined into at least two mining layers along the vertical direction includes: dividing the thick coal seam to be mined into at least two mining layers from top to bottom along the vertical direction; the at least two mining layers include a first layer and a second layer, the second layer is located below the first layer and adjacent to the first layer; Among them, the mining of each layer in sequence from top to bottom includes: in the first layer, excavating and arranging the transportation drift, return air drift and cut-eye of the first layer; dividing the first layer into multiple branch tunnels, and mining the branch tunnels from the inside to the outside by adopting a coal mining method of branch tunnel skipping and then paste filling until the mining of the first layer is completed; after the filling body of the first layer reaches the expected strength, in the second layer, excavating and arranging the transportation drift, return air drift and cut-eye of the second layer; dividing the second layer into multiple branch tunnels, and mining the branch tunnels from the inside to the outside by adopting a coal mining method of branch tunnel skipping and then paste filling until the mining of the second layer is completed.

[0006] According to an implementable method of an embodiment of the present invention, the first layer is divided into a plurality of branch tunnels, and the branch tunnels are mined from the inside to the outside by a coal mining method of branch tunnel skipping and then filling with paste until the first layer is mined, including: dividing the first layer into a plurality of branch tunnels; the plurality of branch tunnels include a first branch tunnel, a second branch tunnel and an Nth branch tunnel; wherein the first branch tunnel is close to the cut eye of the first layer, the second branch tunnel is located between the first branch tunnel and the Nth branch tunnel, and the second branch tunnel is adjacent to the first branch tunnel, and N is a natural number greater than or equal to 3; in the first layer, the first branch tunnel is excavated to connect the first branch tunnel to the transport chute and the return air chute of the first layer; the first branch tunnel is filled with paste; in the first layer, the Nth branch tunnel is excavated to connect the Nth branch tunnel to the transport chute and the return air chute of the first layer; wherein a coal seam of at least one branch tunnel width is reserved between the Nth branch tunnel and the first branch tunnel; The Nth branch tunnel is filled with paste; in the first layer, a second branch tunnel is excavated to connect the second branch tunnel with the transport chute and the return air chute of the first layer; the second branch tunnel is filled with paste.

[0007] According to an implementable method of an embodiment of the present invention, the second layer is divided into a plurality of branch tunnels, and the branch tunnels are mined from the inside to the outside by a coal mining method of branch tunnel skipping and then filling with paste until the second layer is mined, including: dividing the second layer into a plurality of branch tunnels; the plurality of branch tunnels include a first branch tunnel, a second branch tunnel and an Nth branch tunnel; wherein the first branch tunnel is close to the cut eye of the second layer, the second branch tunnel is located between the first branch tunnel and the Nth branch tunnel, and the second branch tunnel is adjacent to the first branch tunnel, and N is a natural number greater than or equal to 3; in the second layer, the first branch tunnel is excavated to connect the first branch tunnel to the transport chute and the return air chute of the second layer; the first branch tunnel is filled with paste; in the second layer, the Nth branch tunnel is excavated to connect the Nth branch tunnel to the transport chute and the return air chute of the second layer; wherein a coal seam of at least one branch tunnel width is reserved between the Nth branch tunnel and the first branch tunnel; The Nth branch tunnel is filled with paste; in the second layer, the second branch tunnel is excavated to connect the second branch tunnel with the transport chute and the return air chute of the second layer; the second branch tunnel is filled with paste.

[0008] According to an implementable method of an embodiment of the present invention, in the second layer, excavating and arranging the transport chute and return air chute of the second layer, including: in the second layer, at a position deviating from the transport chute of the first layer in the horizontal direction, excavating and arranging the transport chute of the second layer, so that the transport chute of the second layer formed is parallel to the transport chute of the first layer, and the upper and lower positions are offset; in the second layer, at a position deviating from the return air chute of the first layer in the horizontal direction, excavating and arranging the return air chute of the second layer, so that the return air chute of the second layer formed is parallel to the return air chute of the first layer, and the upper and lower positions are offset.

[0009] According to an implementable method of an embodiment of the present invention, the directions of the multiple branch lanes divided in the first layer are parallel, the directions of the multiple branch lanes divided in the second layer are parallel, and the directions of the multiple branch lanes divided in the first layer and the multiple branch lanes divided in the second layer are spatially intersected.

[0010] According to an achievable manner of an embodiment of the present invention, the method further includes: mining the branch tunnel by adopting a coal mining method of branch tunnel skipping and then filling with paste, until the first layer is mined, and then filling the transport chute, return air chute and cut-eye of the first layer with paste; and mining the branch tunnel by adopting a coal mining method of branch tunnel skipping and then filling with paste, until the second layer is mined, and then filling the transport chute, return air chute and cut-eye of the second layer with paste.

[0011] According to an implementable manner of the embodiment of the present invention, the first layer is located below the roof of the thick coal seam and adjacent to the roof; Among them, filling the first branch tunnel of the first layer with paste includes: at the top of the first branch tunnel, driving anchor rods and / or anchor cables into the roof of the thick coal seam, and exposing a predetermined length of the anchor rods and / or anchor cables in the first branch tunnel; laying a mesh structure on the bottom plate of the first branch tunnel; filling the first branch tunnel with paste.

[0012] According to an implementable manner of the embodiment of the present invention, in the same layer, adjacent branch tunnels for excavation are spaced 3-5 branch tunnel widths apart.

[0013] According to an implementable manner of the embodiment of the present invention, the thick coal seam is a nearly horizontal thick coal seam or a thick coal seam with an inclination angle of no more than 14°.

[0014] The "three-down" thick coal seam stratified interval paste filling coal mining method provided by the embodiment of the present invention first divides the thick coal seam to be mined into at least two mining layers in the vertical direction, and then mines each layer in sequence from top to bottom; wherein, each layer is excavated and arranged with its own transport chute, return air chute and cut-eye, and each mining layer is divided into multiple branch lanes, and the branch lanes are mined by a coal mining method of branch lane skipping and then paste filling, and the upper layer working face is fully mined and the filling body reaches the expected strength to form an artificial false roof, and then the lower layer is filled and mined. In this way, the upper layer is mined first, and the upper layer working face is fully mined and the filling body reaches the expected strength to form an artificial false roof, and then the lower layer is filled and mined. On this basis, when mining each layer, the branch lane is mined by a coal mining method of branch lane skipping and then paste filling, which can not only effectively support the roof and ensure the stability of the roof, but also realize the full mining of coal resources in each layer and its branch lanes, and improve the resource mining rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 It is a schematic flow chart of the "three-down" thick coal seam layered interval paste filling coal mining method according to an embodiment of the present invention; Figure 2 It is a schematic diagram of the cross arrangement of each layered drift and branch lane of the present invention; Figure 3 It is a layout diagram of the layered working face roadway arrangement on the AA section of the present invention; Figure 4 The layout diagram of the lower layer working face roadway after the upper layer of the AA section forms a false roof in the present invention; Figure 5 Schematic diagram of the dense paste filling process for the upper layered branch tunnel by skipping.

[0017] In the figure: 1-lower layer branch tunnel; 2-upper layer branch tunnel; 3-lower layer filling return air tunnel; 4-upper layer filling return air tunnel; 5-lower layer filling transport tunnel; 6-upper layer filling transport tunnel; 7-upper layer working face cut-eye; 8-lower layer working face cut-eye; 9-auxiliary transport tunnel; 10-transport tunnel; 11-return air tunnel; 12-coal seam roof; 13-coal seam floor; 14-upper layer working face; 15-lower layer working face; 16-roof anchor rod; 17-false roof; 18-excavation branch tunnel; 19-filling branch tunnel; 20-filling pipeline. DETAILED DESCRIPTION

[0018] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0019] It should be clear that the described embodiment is only a component embodiment of the present invention, not all embodiments. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] See also Figure 1 The embodiment of the present invention provides a "three-down" thick coal seam layered interval paste filling coal mining method, comprising the steps of: S11. Divide the thick coal seam to be mined into at least two mining layers along the vertical direction.

[0021] The thick coal seam described in this embodiment includes a thick coal seam with a thickness greater than 3.5 meters, and also includes an extra-thick coal seam with a thickness greater than 8 meters. In some embodiments, the thick coal seam is a nearly horizontal thick coal seam or a thick coal seam with a coal seam inclination angle of no more than 14°.

[0022] Thick coal seams can be divided into two or more mining layers in the vertical direction according to the thickness of the coal seam, the characteristics of the roof and floor plates, the branch mining equipment and the branch support capacity, so that the coal resources in each layer can be mined from top to bottom using a layered mining method.

[0023] S12. Mining each layer in sequence from top to bottom; wherein, each layer is excavated and arranged with its own transport drift, return air drift and cutting eye, and each mining layer is divided into multiple branch tunnels. The branch tunnels are mined by the coal mining method of branch tunnel skipping and then paste filling. After the upper layer working face is fully mined and the filling body reaches the expected strength to form an artificial false roof, the filling mining of the lower layer is carried out.

[0024] The "three-down" thick coal seam stratified interval paste filling coal mining method provided by the embodiment of the present invention first divides the thick coal seam to be mined into at least two mining layers in the vertical direction, and then mines each layer in sequence from top to bottom; wherein, each layer is excavated and arranged with its own transport chute, return air chute and cut-eye, and each mining layer is divided into multiple branch lanes, and the branch lanes are mined by a coal mining method of branch lane skipping and then paste filling, and the upper layer working face is fully mined and the filling body reaches the expected strength to form an artificial false roof, and then the lower layer is filled and mined. In this way, the upper layer is mined first, and the upper layer working face is fully mined and the filling body reaches the expected strength to form an artificial false roof, and then the lower layer is filled and mined. On this basis, when mining each layer, the branch lane is mined by a coal mining method of branch lane skipping and then paste filling, which can not only effectively support the roof and ensure the stability of the roof, but also realize the full mining of coal resources in each layer and its branch lanes, and improve the resource mining rate. In addition, the branch tunnels in each layer adopt the filling coal mining method with interval skipping. The coal mining branch tunnels and the filling branch tunnels do not interfere with each other in time and space, and can operate in parallel, thereby improving coal mining efficiency.

[0025] In some embodiments, dividing the thick coal seam to be mined into at least two mining layers along the vertical direction (step S11) includes: dividing the thick coal seam to be mined into at least two mining layers from top to bottom along the vertical direction; the at least two mining layers include a first layer and a second layer, and the second layer is located below the first layer and adjacent to the first layer.

[0026] The method of mining each layer in sequence from top to bottom includes the following steps: A1. In the first layer, excavate and arrange the transport drift, return air drift and cutting eye of the first layer.

[0027] The first-layer transport chute is formed by excavating from the main transport tunnel, and the first-layer return air chute is formed by excavating from the auxiliary transport tunnel. The first-layer transport chute and the return air chute are excavated and connected to form the first-layer working face cut, and the entire first-layer working face forms a full negative pressure U-shaped ventilation.

[0028] The transport chute is used for transporting coal in the branch tunnels and also for air supply, and the return air chute is used for arranging filling pipelines and return air.

[0029] The cut can be made from within the haulage drift. In some cases, the length of the cut can be determined based on the capacity of the tunnel filling equipment and the coal seam occurrence conditions.

[0030] A2. Divide the first layer into multiple branch tunnels, and mine the branch tunnels from the inside to the outside using a coal mining method of branch tunnel skipping and then paste filling until the first layer is mined.

[0031] The first layered working face is divided into several branch tunnels parallel to the cutting eye. The width of each branch tunnel can be 4-6 meters. The width of the branch tunnel can also be determined based on the ultimate span theory and the mining capacity of the tunneling equipment.

[0032] The branch tunnels of the first layered working face are mined from the inside to the outside, with adjacent branch tunnels mined at intervals of 3-5 branch tunnel widths. After the branch tunnels are excavated, paste filling is carried out in a timely manner. After the branch tunnel filling body reaches the expected strength, the adjacent branch tunnels are mined, and the entire first layered working face is mined in sequence.

[0033] After the first layer working face is mined, the first layer transport chute, return air chute and cutting eye are all filled with paste.

[0034] The paste filling materials described in this embodiment include coal gangue, loess, river sand, slag, fly ash, slag, construction solid waste, etc., which are mixed with cementitious materials to form a cementitious paste filling material for filling.

[0035] A3. When the filling body of the first layer reaches the expected strength, excavate and arrange the transport drift, return air drift and cutting eye of the second layer in the second layer.

[0036] The second-layer transport chute is formed by excavating from the main transport tunnel, and the second-layer return air chute is formed by excavating from the auxiliary transport tunnel. The second-layer transport chute and the return air chute are excavated and connected to form the second-layer working face cut-in, and the entire second-layer working face forms a full negative pressure U-shaped ventilation.

[0037] A4. Divide the second layer into multiple branch tunnels, and mine the branch tunnels from the inside to the outside using a coal mining method of branch tunnel skipping followed by paste filling until the second layer is mined.

[0038] The mining method of the second layer is similar to that of the first layer, and so on, until all mining layers of the thick coal seam are mined.

[0039] In some embodiments, the first layer is divided into a plurality of branch lanes, and the branch lanes are mined from the inside to the outside by a coal mining method of branch lane skipping and then paste filling until the first layer is mined (step A2), including the steps of: A21, dividing the first layer into a plurality of branch lanes; The first layer working face is divided into a plurality of branch tunnels parallel to the cutting eye, and the width of each branch tunnel may be 4-6 meters, and the width of each branch tunnel may also be determined according to the limit span theory and the mining capacity of the tunneling equipment. In some examples, the width of each branch tunnel may be 4.5 meters, in other examples, the width of each branch tunnel may be 4.8 meters, in other examples, the width of each branch tunnel may be 5 meters, and in other examples, the width of each branch tunnel may be 5.6 meters.

[0040] The plurality of branch lanes may include a first branch lane, a second branch lane, and an Nth branch lane; wherein the first branch lane is close to the cut eye of the first layer, the second branch lane is located between the first branch lane and the Nth branch lane, and the second branch lane is adjacent to the first branch lane, and N is a natural number greater than or equal to 3; A22. In the first layer, excavate and mine a first branch tunnel so that the first branch tunnel is connected to the transport chute and the return air chute of the first layer; A23, filling the first branch lane with paste; A24. In the first layer, excavate and mine the Nth branch tunnel to connect the Nth branch tunnel to the transport chute and the return air chute of the first layer; wherein, a coal seam with a width of at least one branch tunnel is reserved between the Nth branch tunnel and the first branch tunnel; in some embodiments, three coal seams with a width of branch tunnels are reserved between the Nth branch tunnel and the first branch tunnel, and in other embodiments, five coal seams with a width of branch tunnels are reserved between the Nth branch tunnel and the first branch tunnel.

[0041] A25, filling the Nth branch lane with paste; A26. In the first layer, excavate and mine a second branch tunnel so that the second branch tunnel is connected to the transport chute and the return air chute of the first layer; A27. Fill the second branch lane with paste.

[0042] After filling the second branch tunnel with paste, the N+1 branch tunnel is excavated in the first layer to connect the N+1 branch tunnel to the transport chute and return air chute of the first layer, and the N+1 branch tunnel is filled with paste. This cycle is repeated to achieve the branch tunnel skipping mining of the first layer and then the paste-filling coal mining method to mine the branch tunnel until the first layer is mined.

[0043] In some embodiments, the second layer is divided into a plurality of branch lanes, and the branch lanes are mined from the inside to the outside by a coal mining method of branch lane skipping and then paste filling until the second layer is mined (step A4), including the steps of: A41. Divide the second layer into a plurality of branch lanes; the plurality of branch lanes include a first branch lane, a second branch lane, and an Nth branch lane; wherein the first branch lane is close to the cut-off point of the second layer, the second branch lane is located between the first branch lane and the Nth branch lane, and the second branch lane is adjacent to the first branch lane, and N is a natural number greater than or equal to 3; A42, in the second layer, excavate and mine the first branch tunnel so that the first branch tunnel is connected to the transport chute and the return air chute of the second layer; A43, filling the first branch lane with paste; A43. In the second layer, excavate and mine the Nth branch tunnel so that the Nth branch tunnel is connected to the transport drift and the return air drift of the second layer; wherein a coal seam of at least one branch tunnel width is reserved between the Nth branch tunnel and the first branch tunnel; A45, filling the Nth branch lane with paste; A46. In the second layer, excavate and mine the second branch tunnel so that the second branch tunnel is connected to the transport chute and the return air chute of the second layer; A47. Fill the second branch lane with paste.

[0044] The second layer is divided into multiple branch tunnels, and the branch tunnels are mined from the inside to the outside using a coal mining method of branch tunnel skipping and then paste filling until the second layer is mined. This is similar to the process of dividing the first layer into multiple branch tunnels, and the branch tunnels are mined from the inside to the outside using a coal mining method of branch tunnel skipping and then paste filling until the first layer is mined.

[0045] In some embodiments, in the second layer, excavating and arranging the transport chute and return air chute of the second layer includes: in the second layer, at a position deviating from the transport chute of the first layer in the horizontal direction, excavating and arranging the transport chute of the second layer, so that the transport chute of the second layer formed is parallel to the transport chute of the first layer, and the upper and lower positions are offset; in the second layer, at a position deviating from the return air chute of the first layer in the horizontal direction, excavating and arranging the return air chute of the second layer, so that the return air chute of the second layer formed is parallel to the return air chute of the first layer, and the upper and lower positions are offset; this will form a structure similar to a fault plane, preventing the top plate of the filling body in the first layer from sinking during the mining of the second layer.

[0046] In some embodiments, the directions of the multiple branch lanes divided in the first layer are parallel, the directions of the multiple branch lanes divided in the second layer are parallel, and the directions of the multiple branch lanes divided in the first layer and the multiple branch lanes divided in the second layer intersect in space (such as a spatial angle of 10-30 degrees). In this way, the branch lanes of the second layer are adjacent to the branch lanes of the first layer and intersect to form a certain inclination arrangement, so as to prevent the top plate of the filling body from sinking in the first layer during the mining process of the second layer.

[0047] In some embodiments, the method also includes: mining the branch tunnel by adopting the coal mining method of branch tunnel skipping and then filling with paste, until the first layer is mined, filling the transport chute, return air chute and cut-eye of the first layer with paste, so as to form a more stable false roof support in the first layer in combination with the filling structure of each branch tunnel of the first layer; and mining the branch tunnel by adopting the coal mining method of branch tunnel skipping and then filling with paste, until the second layer is mined, filling the transport chute, return air chute and cut-eye of the second layer with paste, so as to form a more stable false roof support in the second layer in combination with the filling structure of each branch tunnel of the second layer, thereby providing safety support for the mining of the layer below the second layer (such as the third layer).

[0048] In some embodiments, the first layer is located below the roof of the thick coal seam and adjacent to the roof; wherein, the first branch tunnel of the first layer is filled with paste, comprising: at the top of the first branch tunnel, driving anchor rods and / or anchor cables into the roof of the thick coal seam, and exposing a predetermined length of the anchor rods and / or anchor cables in the first branch tunnel; on the bottom plate of the first branch tunnel, laying a mesh structure; the mesh structure may be a wire mesh; and filling the first branch tunnel with paste.

[0049] In this embodiment, before the first branch tunnel is filled, a mesh structure is laid on the bottom plate of the first branch tunnel. The mesh structure can be connected to the ends of the anchor rods and / or anchor cables exposed in the first branch tunnel to form a paste filling skeleton, enhance the filling effect, and form a filling false ceiling for the lower layered branch tunnel (second branch tunnel).

[0050] The other branch lanes in the first layer and the branch lanes in the second layer can be filled in a manner similar to the first branch lane in the first layer.

[0051] Taking two mining layers as an example, the "three-down" thick coal seam layered interval paste filling coal mining method according to an embodiment of the present invention is specifically described below.

[0052] like Figures 2 to 5 As shown, the "three-down" thick coal seam layered interval paste filling coal mining method according to the embodiment of the present invention specifically comprises the following steps: An upper layer transport tunnel 6 and an upper layer filling return air tunnel 4 are arranged along the coal seam roof, and a working face cut 7 is formed by excavating from the transport drift at the working face boundary. The length of the cut is determined according to the filling capacity of the filling equipment and the coal seam occurrence conditions.

[0053] A plurality of branch tunnels 2 are arranged from the inside to the outside on the upper layer working face 14, and the width of the branch tunnel is determined according to the limit span theory, the mining capacity of the tunneling equipment and the tunnel support capacity.

[0054] The upper layer branch tunnels 2 are mined in sequence from the inside to the outside by the method of first skip mining and then filling. After the branch tunnels are mined, the next branch tunnel is excavated 18 after an interval of 3 to 5 branch tunnels. At the same time, the excavated branch tunnels 19 are filled. Specifically, the two ends of the branch tunnels are first sealed, and the colloid filling of the branch tunnels is carried out through the filling pipeline 20. After the strength of the filling body of the filled branch tunnel reaches the expected strength, the adjacent branch tunnels are mined. The operation is repeated until the upper layer working face is completely mined.

[0055] After the upper layer transport chute 6, return air chute 4 and cut-eye 7 are filled, that is, all upper layer working faces are filled and mined, a false top 17 of the filling body is formed. After reaching the expected strength, the lower layer working face 15 is rearranged for filling and mining. The filling and mining process of the lower layer working face 15 is similar to the filling and mining process of the upper layer working face 14.

[0056] After the upper layer mining and filling is completed, the branch tunnels and chute are filled. The upper layer branch tunnels and chute are arranged along the coal seam roof, and the lower layer branch tunnel 1, transport chute 5, and return air chute 3 are arranged along the upper layer filling body. After the upper layer is fully filled, there is no connection between the filling bodies of each branch tunnel and between the branch tunnel and the chute filling body, which is similar to the fault surface structure. Therefore, in order to stabilize the filling body roof, the chute of the upper and lower layers are staggered and arranged in parallel; the upper and lower layer mining branch tunnels are arranged at a certain angle to prevent the upper layer filling body roof from sinking as a whole when the lower layer is mined. This coal mining method solves the problems of low coal resource recovery rate, mining capacity and support difficulties in the "three lower" thick coal seam covering resource recovery process, and has many advantages of safety, efficiency, economy and practicality.

[0057] Compared with the existing backfill coal mining technology, the technical solution adopted in the above embodiment of the present invention has the following beneficial effects: 1. The present invention utilizes the upper layer filling body as a false roof to ensure safe and efficient recovery of the lower layer working face, leaving no coal behind, with a high coal recovery rate and good filling effect, and can control the movement of the overlying rock strata and protect surface buildings.

[0058] 2. The present invention mines thick coal seams in layers, which is less affected by mining equipment and tunnel support capacity, has a simple process, flexible equipment operation, and strong applicability. The present invention cleverly designs the parallel staggered arrangement of each layered tunnel (transport chute, return air chute) and the cross arrangement of filling and mining branch tunnels to ensure safe and efficient mining of each layer. The present invention is practicable and has a good prospect for promotion and application.

[0059] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0060] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A "three-down" thick coal seam layered interval paste filling coal mining method, characterized in that: include: Dividing the thick coal seam to be mined into at least two mining layers in the vertical direction; the thickness of the thick coal seam is greater than 3.5 meters; Each layer is mined in sequence from top to bottom; each layer is excavated and arranged with its own transport drift, return air drift and cutting eye, and each mining layer is divided into multiple branch tunnels. The branch tunnels are mined by the coal mining method of branch tunnel skipping and then paste filling. After the upper layer working face is fully mined and the filling body reaches the expected strength to form an artificial false roof, the filling mining of the lower layer is carried out.

2. The "three-down" thick coal seam layered interval paste filling coal mining method according to claim 1 is characterized in that: The thick coal seam to be mined is divided into at least two mining layers along the vertical direction, including: Dividing the thick coal seam to be mined into at least two mining layers from top to bottom along the vertical direction; the at least two mining layers include a first layer and a second layer, the second layer is located below the first layer and adjacent to the first layer; The mining of each layer in sequence from top to bottom includes: In the first layer, excavating and arranging the transport drift, return air drift and cut-eye of the first layer; Dividing the first layer into a plurality of branch lanes, mining the branch lanes from the inside to the outside by adopting a coal mining method of branch lane skipping and then paste filling until the first layer is mined; When the filling body of the first layer reaches the expected strength, in the second layer, the transport drift, return air drift and cut-eye of the second layer are excavated and arranged; The second layer is divided into a plurality of branch tunnels, and the branch tunnels are mined from the inside to the outside by adopting a coal mining method of branch tunnel skipping and then paste filling until the second layer is mined.

3. The "three-down" thick coal seam layered interval paste filling coal mining method according to claim 2 is characterized in that: The first layer is divided into a plurality of branch lanes, and the branch lanes are mined from the inside to the outside by using a coal mining method of branch lane skipping and then paste filling until the first layer is mined, including: The first layer is divided into a plurality of branch lanes; the plurality of branch lanes include a first branch lane, a second branch lane and an Nth branch lane; wherein the first branch lane is close to the cut-eye of the first layer, the second branch lane is located between the first branch lane and the Nth branch lane, and the second branch lane is adjacent to the first branch lane, and N is a natural number greater than or equal to 3; In the first layer, excavating a first branch tunnel so that the first branch tunnel is connected to the transport chute and the return air chute of the first layer; Filling the first branch lane with paste; In the first layer, excavating and mining the Nth branch tunnel so that the Nth branch tunnel is connected to the transport drift and the return air drift of the first layer; wherein a coal seam of at least one branch tunnel width is reserved between the Nth branch tunnel and the first branch tunnel; Filling the Nth branch lane with paste; In the first layer, excavating a second branch tunnel so that the second branch tunnel is connected to the transport chute and the return air chute of the first layer; The second branch lane is filled with paste.

4. The "three-down" thick coal seam layered interval paste filling coal mining method according to claim 2 is characterized in that: The second layer is divided into a plurality of branch lanes, and the branch lanes are mined from the inside to the outside by using a coal mining method of branch lane skipping and then paste filling until the second layer is mined, including: The second layer is divided into a plurality of branch lanes; the plurality of branch lanes include a first branch lane, a second branch lane and an Nth branch lane; wherein the first branch lane is close to the cut-eye of the second layer, the second branch lane is located between the first branch lane and the Nth branch lane, and the second branch lane is adjacent to the first branch lane, and N is a natural number greater than or equal to 3; In the second layer, excavating and mining the first branch tunnel so that the first branch tunnel is connected to the transport chute and the return air chute of the second layer; Filling the first branch lane with paste; In the second layer, excavate and mine the Nth branch tunnel so that the Nth branch tunnel is connected to the transport drift and the return air drift of the second layer; wherein a coal seam of at least one branch tunnel width is reserved between the Nth branch tunnel and the first branch tunnel; Filling the Nth branch lane with paste; In the second layer, excavating a second branch tunnel so that the second branch tunnel is connected to the transport chute and the return air chute of the second layer; The second branch lane is filled with paste.

5. The "three-down" thick coal seam layered interval paste filling coal mining method according to claim 2 is characterized in that: In the second layer, excavating and arranging the transport drift and return air drift of the second layer includes: In the second layer, at a position that deviates from the transport drift of the first layer in the horizontal direction, excavating and arranging the transport drift of the second layer, so that the transport drift of the second layer is parallel to the transport drift of the first layer and the upper and lower positions are offset; In the second layer, at a position horizontally deviating from the return air chute of the first layer, the return air chute of the second layer is excavated and arranged so that the return air chute of the second layer formed is parallel to the return air chute of the first layer and the upper and lower positions are offset.

6. The "three-down" thick coal seam layered interval paste filling coal mining method according to claim 2 is characterized in that: The directions of the multiple branch lanes divided in the first layer are parallel, the directions of the multiple branch lanes divided in the second layer are parallel, and the directions of the multiple branch lanes divided in the first layer and the multiple branch lanes divided in the second layer intersect in space.

7. The "three-down" thick coal seam layered interval paste filling coal mining method according to claim 2 is characterized in that: The method further comprises: The branch tunnel is mined by adopting the coal mining method of skip mining and then filling with paste until the first layer is mined, and then the transport chute, return air chute and cut-hole of the first layer are filled with paste; and The branch tunnel is mined by adopting the coal mining method of branch tunnel skipping and then filling with paste until the second layer is mined, and then the transport chute, return air chute and cut eye of the second layer are filled with paste.

8. The "three-down" thick coal seam layered interval paste filling coal mining method according to claim 3 is characterized in that: The first layer is located below the roof of the thick coal seam and adjacent to the roof; Wherein, the first branch lane of the first layer is filled with paste, including: At the top of the first branch tunnel, driving anchor rods and / or anchor cables into the roof of the thick coal seam, and exposing a predetermined length of the anchor rods and / or anchor cables in the first branch tunnel; On the bottom plate of the first branch lane, lay mesh structure members; Fill the first alley with paste.

9. The "three-down" thick coal seam layered interval paste filling coal mining method according to claim 3 or 4, characterized in that: In the same layer, adjacent branch tunnels are excavated and mined at a distance of 3-5 branch tunnel widths.

10. The "three-down" thick coal seam layered interval paste filling coal mining method according to claim 1, characterized in that: The thick coal seam is a nearly horizontal thick coal seam or a thick coal seam with an inclination angle of no more than 14°.

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