Coal pillar full recovery mining method coordinated with caving and filling of adjacent longwall face

Abstract

The present application relates to the technical field of coal mining, in particular to a coal pillar full recovery mining method for coordination of caving and filling of adjacent longwall faces, which comprises: sequentially dividing the mining faces of a mining area along the width direction of the mining faces into a first mining face, a second mining face and a third mining face, the face length of the second mining face being greater than the face length of the first mining face and the face length of the third mining face, the first mining face and the third mining face using the filling method to treat the roof, and the second mining face using the caving method to treat the roof. The coal pillar full recovery mining method for coordination of caving and filling of adjacent longwall faces reduces the filling cost and improves the coal mining rate.

Description

Technical Field

[0001] This invention relates to the field of coal mining technology, specifically to a long-mining, short-filling coal mining method. Background Technology

[0002] Longwall mining in coal mines employs caving and backfilling methods to treat the roof. The caving method causes rock strata damage, and natural roof collapse can lead to stress concentration and surrounding rock failure in adjacent roadways, rendering the roadways unusable. The backfilling method treats the roof after mining, supporting it by filling the space after coal seam excavation. Backfilling effectively controls surface subsidence and prevents rock strata fracturing, but it has low mining efficiency and high backfilling costs. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose a method for full recovery mining of coal pillars that coordinates the collapse and backfilling of adjacent longwall working faces, eliminating the need for separate roadway excavation, reducing backfilling costs, and increasing coal extraction rates.

[0004] An embodiment of the present invention provides a coal pillar full recovery mining method for coordinating the collapse and backfilling of adjacent longwall working faces, comprising:

[0005] The mining face of the mining area is divided into a first mining face, a second mining face, and a third mining face along the width direction. The length of the second mining face is greater than the length of the first mining face and the length of the third mining face.

[0006] The first and third mining faces used the backfilling method to treat the roof, while the second mining face used the caving method.

[0007] The coal pillar full recovery mining method of the present invention, which coordinates the collapse and backfilling of adjacent longwall working faces, eliminates the need for separate roadway excavation, reduces backfilling costs, and increases coal mining efficiency.

[0008] In some implementations, the mining area includes a return airway and a haulage roadway. The return airway is located between the first and second mining faces and is connected to the main return airway. The haulage roadway is located between the second and third mining faces and is connected to the main haulage roadway.

[0009] A return airway is arranged during the mining of the first mining face, and a transport airway is arranged during the mining of the third mining face. The return airway and the transport airway are supported.

[0010] In some implementations, the goaf formed by the first mining face is filled, and the goaf formed by the third mining face is filled.

[0011] In some implementations, tests are conducted on the goaf area after filling the first mining face to determine the solidification of the filling material, and tests are conducted on the goaf area after filling the second mining face to determine the solidification of the filling material.

[0012] In some implementations, the first, second, and third mining faces all employ forward-moving mining.

[0013] The first and third mining faces are mined before the second mining face. When the first mining face is mined, a return airway is set up and roadway support is provided. After the first mining face and the goaf formed by the first mining face are filled, the third mining face is mined.

[0014] In some implementations, the first and third mining faces both employ forward mining, while the second mining face employs backward mining.

[0015] During the mining of the first working face, a return airway is arranged, roadway support is provided, and the goaf of the first working face is filled.

[0016] When the third mining face is being mined, a transport roadway is set up and roadway support is provided. The goaf of the third mining face is then filled. After the goaf of the first and third mining faces is filled and the filling material in the goaf has solidified, the mining of the second mining face is started.

[0017] In some implementations, the first, second, and third mining faces all adopt a retreat mining method, with the transport roadway and return airway being excavated in advance, and the support in the return airway and transport roadway being provided before the mining of the first, second, and third mining faces begins.

[0018] In some implementations, the dimension of the second mining face in the width direction of the mining face is b, and 450m ≥ b ≥ 200m.

[0019] In some implementations, the width of the transport roadway in the mining face is set as d, and the width of the return air roadway in the mining face is set as e. Then d and e satisfy: 5m≤d=e≤6m.

[0020] In some implementations, the length of the first mining face is 'a' and the length of the third mining face is 'c'.

[0021] a and c satisfy the condition that a is greater than c. c is greater than ,

[0022] ,

[0023] in, r is the critical width of the coal pillar, in meters; r is the average apparent density of the overburden, in kg / m³. 3 H represents the average mining depth in meters (m); Sc represents the uniaxial compressive strength of the standard laboratory specimen of the coal seam in MPa; g represents the acceleration due to gravity. B represents the width of the overburden supporting the coal pillar, in meters; h represents the height of the coal pillar within the mining area, in meters. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the first mining face in an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the collapse of the second mining face in an embodiment of the present invention.

[0026] Figure 3 This is a schematic diagram of the collapse of the third mining face in an embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram of the collapse of the second mining face in an embodiment of the present invention.

[0028] Figure label:

[0029] First mining face 1, first goaf 101, second mining face 2, second goaf 201, third mining face 3, third goaf 301, return airway 4, transport roadway 5,

[0030] The mining face is 10, the return airway is 20, the transport airway is 30, and the mining area is 40. Detailed Implementation

[0031] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0032] An embodiment of the present invention provides a coal pillar full recovery mining method for coordinating the collapse and backfilling of adjacent longwall working faces, comprising:

[0033] The mining face 10 of mining area 40 is divided into a first mining face 1, a second mining face 2, and a third mining face 3 along the width direction. The length of the second mining face 2 is greater than the length of the first mining face 1 and the length of the third mining face 3.

[0034] The first mining face 1 and the third mining face 3 used the backfilling method to treat the roof, while the second mining face 1 used the caving method to treat the roof.

[0035] From left to right, the working faces are designated as the first working face 1, the second working face 2, and the third working face 3. The second working face 2 uses the caving method to treat the roof, while the first working face 1 or the third working face 3 uses the backfilling method. The goaf formed after the third working face 3 is designated as the third goaf 301, the goaf formed after the first working face 1 is designated as the first goaf 101, and the goaf formed after the second working face 2 is designated as the second goaf 2. The third goaf 301 and the first goaf 101 are backfilled, and the roof above the second goaf 2 is treated using the caving method.

[0036] That is, the first mining face 1 and the third mining face 3 use the filling method to treat the third goaf 301 and the first goaf 101, while the second mining face 2 uses the caving method to treat the second goaf 2.

[0037] Alternatively, it can be understood as supporting the rock strata of the third goaf 301 and the first goaf 101. Since the rock strata are a single unit, the filling material of the third goaf 301 and the first goaf 101 provides a certain degree of support to the rock strata above the second goaf 2.

[0038] That is, the filling materials of the third goaf 301 and the first goaf 101 provide support to the rock strata of the first goaf 101 and the third goaf 301 to a certain extent, reducing the range of rock strata fracture and collapse in goaf 2.

[0039] It should be noted that the first mining face 1, the second mining face 2, and the third mining face 3 can be mined simultaneously, or they can be mined at different times.

[0040] The coal mining method of long filling and short mining according to the embodiments of the present invention, by performing collapse treatment on the second goaf 2 and filling treatment on the third goaf 301 and the first goaf 101, eliminates the need to fill the entire mining area 40, thereby avoiding ground subsidence, improving coal mining efficiency, and reducing mining costs. Moreover, after the first goaf 101 and the third goaf 301 are filled, they provide a certain support for the second goaf 2, eliminating the need to leave coal pillars, thus improving coal mining efficiency and coal recovery rate.

[0041] In some implementations, the mining area 40 is provided with a return airway 4 and a transport airway 5. The return airway 4 is located between the first mining face 1 and the second mining face 2, and is connected to the main return airway 20. The transport airway 5 is located between the second mining face 2 and the third mining face 3, and is connected to the main transport airway 30.

[0042] During the mining of the first mining face 1, a return airway 4 is arranged, and during the mining of the third mining face 3, a transport airway 5 is arranged, and the return airway 4 and the transport airway 5 are supported.

[0043] Specifically, such as Figures 1 to 4 As shown, mining area 40 is equipped with a return airway 4 and a transport roadway 5, which extend in the front-to-back direction. The return airway 4 is located between the first mining face 1 and the second mining face 2, and is used for ventilation of mining area 40. The transport roadway 5 is located between the second mining face 2 and the third mining face 3, and is used for transporting materials and conveying coal. When mining the first mining face 1 and the third mining face 3, after the coal mining machine has finished mining, it advances in the mining direction, and the anchor bolt support machine supports the transport roadway 5 and the return airway 4. That is, the roadways are formed by the coal mining machine cutting coal, and the support is arranged in the transport roadway 5 or the return airway 4. Construction equipment is used to support the return airway 4 and the transport airway 5. For example, it can be supported by a bolting machine to complete the bolting support, or by using existing support devices or equipment such as scaffolding support or roadway supports. At the same time, the roadway sides are supported, that is, the roadway sides of the transport airway 5 and the return airway 4 are supported, so that the first mining face 1 and the third mining face 3 can be mined and the roadways are arranged at the same time, that is, the transport airway 5 and the return airway 4 are arranged, so as to facilitate the mining and transportation of coal in the second mining face 2, and to ventilate the mining area 40 to avoid excessive concentration of gas or carbon dioxide in the mining area 40. The width direction of the mining face 10 is left and right.

[0044] Meanwhile, transport roadway 5 and return air roadway 4 can also be used to transport backfill materials, which can then be used to fill and grout the first goaf 101 of the first mining face 1 or the third goaf 301 of the third mining face 3, improving mining efficiency. At the same time, after mining coal in the first mining face 1 and the third mining face 3, support is carried out to avoid the cross-operation of coal cutting and support, saving roadway support time and preventing coal cutting from affecting roadway support, or vice versa.

[0045] The coal mining method of long-filling short-mining in this embodiment of the invention involves, after mining in the first mining face 1 and the third mining face 3, arranging support construction equipment in the roadway to complete the support of the return airway 4 or the transport roadway 5, such as anchor bolt support, canopy support or roadway support, thereby completing the arrangement of the return airway 4 and the transport roadway 5. This facilitates the transportation of the dropped coal during construction and avoids excessive concentrations of methane or carbon dioxide in the mining area 40. After the coal is dropped by the coal mining machine, it is supported by the anchor bolt machine, realizing that the coal dropping and support operations do not overlap, thus improving coal mining efficiency.

[0046] In some implementations, the goaf formed by the first mining face 1 is filled, and the goaf formed by the third mining face 3 is filled.

[0047] Specifically, such as Figures 1 to 4 As shown, during the forward advance of the first mining face 1, and after the support of the return airway 4 is completed, the first goaf 101 is filled. Grouting is performed by setting up both a surface filling station and an underground filling station. For example, the surface filling station is suitable for providing the filling material, and the underground filling station is connected to the surface filling station to grout the filling material into the first goaf 101, thereby allowing the first mining face 1 to continue advancing.

[0048] As the third mining face 3 advances and the support for the post-mining transport roadway 5 is completed, the third goaf 301 is filled. Grouting is performed using both surface and underground filling stations. For example, the surface filling station provides the filling material, and the underground filling station is connected to the surface station to inject the filling material into the third goaf 301, allowing the third mining face 3 to continue advancing.

[0049] The coal mining method of long filling and short mining in this embodiment of the invention fills the third goaf 301 and the first goaf 101, thereby eliminating the need to leave coal pillars to support the rock strata above the goaf, thus improving the coal mining rate, and eliminating the need to excavate the transport roadway 5 and return airway 4 separately in advance, thereby reducing the coal mining cost.

[0050] In some implementations, tests were conducted on the goaf area after filling the first mining face 1 to determine the solidification of the filling material, and tests were conducted on the goaf area after filling the third mining face 3 to determine the solidification of the filling material.

[0051] Specifically, such as Figures 1 to 4 As shown, the filling materials of the first goaf 101 and the third goaf 301 are tested to check whether the filling materials have solidified and formed. The filling materials can be cement grouting filling, or on-site gangue, sand, urban garbage near the mining area, etc.

[0052] In some implementations, the first mining face 1, the second mining face 2, and the third mining face 3 all adopted the forward mining method.

[0053] The first mining face 1 and the third mining face 3 are mined before the second mining face 2. When the first mining face 1 is mined, the return airway 4 is arranged and the roadway is supported. After the goaf formed by the first mining face 1 or the third mining face 3 is filled, the second mining face 2 is mined.

[0054] Specifically, such as Figures 1 to 4As shown, the first mining face 1 employs an advancing mining method. For example, the first mining face 1 begins mining from one end adjacent to the haulage roadway 30 and the return air roadway 20, and proceeds away from the haulage roadway 30 and the return air roadway 20. That is, the first mining face 1 mines from the rear end to the front end of the mining area 40. Similarly, the third mining face 3 employs an advancing mining method. For example, the third mining face 3 begins mining from one end adjacent to the haulage roadway 30 and the return air roadway 20, and proceeds away from the haulage roadway 30 and the return air roadway 20. That is, the third mining face 3 mines from the rear end to the front end of the mining area 40.

[0055] During the mining of the first mining face 1, after the coal chuck completes its coal cutting operation, the bolting machine provides bolt support for the return airway 4. During the mining of the third mining face 3, after the coal chuck completes its coal cutting operation, the bolting machine provides bolt support for the transport airway 5. The second mining face 2 is mined from the rear end to the front end of mining area 40.

[0056] Understandably, the first mining face 1 and the third mining face 3 can be mined first. During the mining of the first mining face 1, a return airway 4 can be laid out, and during the mining of the third mining face 3, a transport airway 5 can be laid out. After the first mining face 1 and the third mining face 3 have been mined for a certain distance, the first goaf 101 and the third goaf 301 should be backfilled in a timely manner to prevent collapses in the first goaf 101 and the third goaf 301 from impacting the transport airway 5 or the return airway 4. Personnel and equipment in the transport airway 5 and the return airway 4 should be protected.

[0057] After the goaf formed by the first mining face 1 or the third mining face 3 is filled, the second mining face 2 will be mined.

[0058] This can be understood as follows: after the first mining face 1 and the third mining face 3 have been mined for a certain distance, the first goaf 101 and the third goaf 301 are filled, which means that the second mining face 2 begins to mine coal. In other words, the positions corresponding to the first goaf 101 and the third goaf 301 in the left and right directions of the coal mining position of the second mining face 2 have been filled. Therefore, when the second mining face 2 is mined, the left and right ends of the second mining face 2 are supported by the filling body, which improves the stability and safety of the second mining face 2 during coal mining.

[0059] Alternatively, after the mining of the first mining face 1 and the third mining face 3 is completed, and the first goaf 101 and the third goaf 301 are filled, the mining of the second mining face 2 can begin, thereby improving the stability and safety of the mining of the second mining face 2.

[0060] In some implementations, both the first mining face 1 and the third mining face 3 adopt the forward mining method, while the second mining face 2 adopts the backward mining method.

[0061] During the mining of the first working face 1, a return airway 4 is arranged, roadway support is provided, and the goaf of the first working face 1 is filled.

[0062] When mining the third mining face 3, a transport roadway is arranged and roadway support is provided. The goaf of the third mining face 3 is filled. After the goafs of the first mining face 1 and the third mining face 3 are filled and the filling material in the goaf solidifies, mining of the second mining face 2 is started.

[0063] Specifically, such as Figures 1 to 4 As shown, the first mining face 1 and the third mining face 3 are mined first. During the mining of the first mining face 1, a return airway 4 is laid out. During the mining of the third mining face 3, a transport airway 5 is laid out. After the first mining face 1 and the third mining face 3 have been mined for a certain distance, the first goaf 101 and the third goaf 301 are filled, and the transport airway 5 and the return airway 4 are supported to prevent collapses in the first goaf 101 and the third goaf 301 from impacting the transport airway 5 or the return airway 4. Personnel and equipment in the transport airway 5 and the return airway 4 are protected.

[0064] After the mining of the first mining face 1 and the third mining face 3 is completed, and the first goaf 101 and the third goaf 301 are filled, the retreat mining of the second mining face 2 will begin, that is, mining from the front end to the rear end, to improve the stability and safety of mining the second mining face 2.

[0065] The coal pillar recovery mining method for coordinated collapse and backfilling of adjacent longwall working faces in this invention involves advancing mining in both the first and third mining faces 1 and 3. During mining, roadways are arranged, namely, transport roadways 5 and return airways 4. Before mining the second mining face 2, materials are transported via the return airway 4. During mining of the second mining face 2, coal is transported via the transport roadway 5. This eliminates the need for advance roadway excavation to form transport roadways 5 or return airways 4, reducing costs. Furthermore, after backfilling of the first and third goaf areas 101 and 301, no coal pillars are required, enabling retreat mining of the second mining face 2. This increases the coal extraction volume, stability, and safety of the mining area 40.

[0066] Furthermore, after the first mining face 1 and the third mining face 3 have been mined at a predetermined distance, the goaf areas of the first mining face 1 and the third mining face 3 are filled. First, the transport roadway 5 and the return air roadway 4 are supported, and then the goaf areas of the first mining face 1 and the third mining face 3 are filled, that is, the first goaf 101 and the third goaf 301 are filled. This achieves non-interference between coal cutting and support, improving coal mining efficiency, and also achieves non-interference between support and filling operations, improving support and filling efficiency.

[0067] In some implementations, the dimension of the second mining face 2 in the width direction of the mining face 10 is b, and 450m ≥ b ≥ 200m.

[0068] Specifically, such as Figures 1 to 4 As shown, the dimension of the second mining face 2 in the left-right direction is b, and b satisfies 450m≥b≥200m. Therefore, the length of the second mining face 2 can be set to increase the coal mining volume. b can be 450m, 430m, 400m, 350m, 300m, 290m, 230m, 240m, 220m, 210m, or 200m.

[0069] By setting the length of the second mining face 2 in the left-right direction, the limited support provided by the first goaf 101 and the third goaf 301 to the rock strata above the mining area 40 after filling is avoided. This prevents the second mining face 2 from being too long, which could lead to the collapse of the second goaf 201 and ground subsidence. Simultaneously, it avoids the second mining face 2 being too short, resulting in a smaller size of the mining area 40 in the left-right direction. Since the first goaf 101 and the second goaf 301 are filled, the overall filling cost of the mining area 40 is high. By setting the length of the second mining face 2 in the left-right direction, coal mining costs can be controlled, and coal face subsidence can be prevented.

[0070] In some embodiments, the first mining face 1, the second mining face 2, and the third mining face 3 all adopt a retreat mining method, excavating the transport roadway 5 and the return air roadway 4 in advance, supporting the return air roadway 4 and the transport roadway 6, and then starting the mining of the first mining face 1, the second mining face 2, and the third mining face 3.

[0071] Specifically, such as Figures 1 to 4As shown, the first mining face 1, the second mining face 2, and the third mining face 3 all mine from the front end of the mining area 40 to the rear end, that is, from the end of the mining area 40 furthest from the main haulage roadway 30 towards the adjacent main haulage roadway 30. Before mining, the return airway 4 and the haulage roadway 5 are excavated in advance and supported. Then, mining of the first mining face 1, the second mining face 2, and the third mining face 3 can begin. The first mining face 1 and the third mining face 3 can be mined before the second mining face 2, or they can be mined simultaneously with the second mining face 2. While mining the first mining face 1 and the third mining face 3, after mining a predetermined distance, the goaf of the first mining face 1 and the third mining face 3 is filled. This achieves no interference between coal cutting and support, improving coal mining efficiency, and no interference between support and filling operations, improving support and filling efficiency. By excavating the transport roadway 5 and return airway 4 in advance, the rock strata above mining area 40 can be supported, improving the stability and safety of coal mining in mining area 40. Furthermore, the first mining face 1 and the third mining face 3 use backfilling to treat the goaf, while the second mining face 2 uses the caving method to treat the goaf, supporting the rock strata in mining area 40, avoiding ground subsidence while reducing backfilling costs.

[0072] In some implementations, the dimension of the transport roadway 5 in the width direction of the working face 10 in the mining area 40 is set as d, and the dimension of the return air roadway 4 in the width direction of the working face 10 in the mining area 40 is set as e. Then d and e satisfy: 5m≤d=e≤6m.

[0073] Specifically, such as Figures 1 to 4 As shown, the spacing of the return airway 4 in the left and right directions is e, and d and e satisfy: 5m ≤ d = e ≤ 7m. For example, d and e can be 5m, 5.5m, 6.2m, 6.5m, or 7.0m, arranged according to the actual collapse conditions of the second goaf 2. Since the material and hardness of each rock layer are different, the collapse amount during collapse is different. When the collapse amount is large, that is, when there are many layers of rock that collapse, the size of d and e is set to 7.0m, thereby protecting the transport airway 5 and the return airway 4.

[0074] Understandably, the dimensions of the first mining face 1 and the third mining face 3 in the left-right direction can be determined based on the length of the second mining face 2. For example, when the length of the second mining face 2 is 200m, the lengths of the first mining face 1 and the third mining face 3 can be set to 50m.

[0075] When the length of the second mining face 2 is 450m, the lengths of the first mining face 1 and the third mining face 3 are set to 100m. This allows the filling material of the first goaf 101 and the third goaf 301 to provide some support to the rock strata above the second goaf, thereby improving the stability of coal mining.

[0076] It also facilitates ventilation in the return airway 4 when the second mining face 2 is being mined, and transport airway 5 is used to transport coal when the second mining face 2 is being mined.

[0077] The coal mining method of long filling and short mining in this embodiment of the invention sets d and e to set the dimensions of return airway 4 and transport airway 5 in the left and right directions. The size of d and e is set according to the on-site collapse conditions to improve the safety and stability of coal mining in the second mining face 2.

[0078] In some implementations, the length of the first mining face 1 is 'a' and the length of the third mining face 3 is 'c', where 'a' and 'c' satisfy the condition that 'a' is greater than 'c'. c is greater than And 50m≤a=c≤100m,

[0079] ,

[0080] in, 1 is the critical width of the coal pillar, in meters; r is the average apparent density of the overburden, in kg / m³; H is the average mining depth, in meters; Sc is the uniaxial compressive strength of the standard laboratory specimen of the coal seam, in MPa. acceleration due to gravity B represents the width of the overburden supporting the coal pillar, in meters.

[0081] h represents the height of the coal pillar within the mining area 40, in meters.

[0082] Specifically, such as Figures 1 to 4 As shown, trial mining can be conducted on coal seams close to the mining area. Samples are taken on-site and sent to the laboratory to determine the average apparent density of the overlying strata. The average mining depth refers to the distance between the mined coal seam and the surface, i.e., the average distance of mining area 40 from the surface. h is the height of the coal pillar within mining area 40. The bearing width of the coal pillar is the dimension of the direct roof above the coal pillar in the left-right direction, without any collapse or fracture, and is then calculated. Furthermore, 50m ≤ a = c ≤ 100m facilitates on-site personnel in estimating the face length range of the first mining face 1 and the third mining face 3. The face lengths of the first mining face 1 and the third mining face 3 are determined based on the actual coal mining equipment's dimensions in the left-right direction. This avoids situations where the face lengths of the first mining face 1 and the third mining face 3 are too small, resulting in insufficient support for the rock strata in the second goaf 201, leading to collapse and potential danger. Simultaneously, it avoids excessive backfilling, which would result in higher costs.

[0083] The coal mining method of long filling and short mining in this embodiment of the invention limits the length of the first mining face 1 and the third mining face 3, so that the first goaf 101 and the third goaf 301 after filling can provide a certain support to the rock strata above the second goaf 2, thereby improving the safety and stability of coal mining in the second mining face 2.

[0084] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0085] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0086] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0087] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0088] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0089] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for full recovery of coal pillars in mining with coordinated caving and backfilling of adjacent longwall working faces, characterized in that, include: The mining face of the mining area is divided into a first mining face, a second mining face, and a third mining face along the width direction. The length of the second mining face is greater than the length of the first mining face and the length of the third mining face. The first and third mining faces used the backfilling method to treat the roof, while the second mining face used the caving method to treat the roof. The mining area includes a return airway and a haulage airway. The return airway is located between the first and second mining faces and is connected to the main return airway. The haulage airway is located between the second and third mining faces and is connected to the main haulage airway. When the first mining face is being mined, a return airway is arranged, and when the third mining face is being mined, a transport airway is arranged. The return airway and the transport airway are supported. Let the width of the transport roadway in the mining face be d, and the width of the return air roadway in the mining face be e. Then d and e satisfy: 5m≤d=e≤6m. The length of the first mining face is 'a' and the length of the third mining face is 'c'. a and c satisfy the condition that a is greater than c. c is greater than , ,in, r is the critical width of the coal pillar, in meters; r is the average apparent density of the overburden, in kg / m³. 3 H represents the average mining depth in meters (m); Sc represents the uniaxial compressive strength of the standard laboratory specimen of the coal seam in MPa; g represents the acceleration due to gravity. B represents the width of the overburden supporting the coal pillar, in meters. h represents the height of the coal pillar within the mining area, measured in meters (m).

2. The method for full recovery of coal pillars with coordinated caving and backfilling of adjacent longwall working faces according to claim 1, characterized in that, The goaf formed by the first mining face is filled, and the goaf formed by the third mining face is filled.

3. The method for full recovery mining of coal pillars with coordinated caving and backfilling of adjacent longwall working faces according to claim 2, characterized in that, Tests were conducted on the goaf area after filling the first mining face to determine the solidification and shaping of the filling material. Tests were also conducted on the goaf area after filling the second mining face to determine the solidification and shaping of the filling material.

4. The method for full recovery mining of coal pillars with coordinated caving and backfilling of adjacent longwall working faces according to claim 3, characterized in that, The first, second, and third mining faces all employ the forward-advancing mining method. The first and third mining faces are mined before the second mining face. When the first mining face is being mined, a return airway is set up and roadway support is provided. After the goaf formed by the first and third mining faces is filled, the second mining face is mined.

5. The method for full recovery mining of coal pillars with coordinated caving and backfilling of adjacent longwall working faces according to claim 3, characterized in that, The first and third mining faces both employ forward mining, while the second mining face employs backward mining. During the mining of the first working face, a return airway is arranged, roadway support is provided, and the goaf of the first working face is filled. When the third mining face is being mined, a transport roadway is set up and roadway support is provided. The goaf of the third mining face is then filled. After the goaf of the first and third mining faces is filled and the filling material in the goaf has solidified, the mining of the second mining face is started.

6. The method for full recovery mining of coal pillars with coordinated caving and backfilling of adjacent longwall working faces according to claim 1, characterized in that, The first, second, and third mining faces all employ a retreat mining method, with the transport roadway and return airway advanced in advance. Support is provided in the return airway and transport roadway before mining begins on the first, second, and third mining faces.

7. The method for full recovery mining of coal pillars with coordinated caving and backfilling of adjacent longwall working faces according to claim 1, characterized in that, The second mining face has a width dimension of b, and 450m ≥ b ≥ 200m.

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