Methods for complete recovery of coal pillars in mining areas

Abstract

This invention belongs to the field of coal mining and provides a method for the complete recovery of coal pillars in a mining area. The method includes: simultaneously supporting the haulage roadway between the current and next mining faces while mining the current working face; after the current working face is completed, retracting the hydraulic supports within the current working face using a retraction channel, and supporting the retraction channel corresponding to the current working face; completing the mining of all working faces and the support of corresponding retraction channels using the mining and support methods of the current working face; and recovering the coal pillars using the mining area haulage roadway and the retraction channel. This invention, by supporting the haulage roadway in the mining face, eliminates the need to leave section coal pillars during the mining process. During the hydraulic support retraction, the retraction channel is supported, preserving the retraction channel. The coal pillars are then completely recovered using the retraction channel and the mining area haulage roadway, thereby improving the coal pillar recovery rate.

Description

Technical Field

[0001] This invention relates to the field of coal mining, and more particularly to a method for the complete recovery of coal pillars in a mining area. Background Technology

[0002] Most mining areas employ longwall mining, which involves leaving coal pillars in the roadways for support, thus increasing safety during the mining process. After all working faces in the mining area have been mined out (after which the mining area becomes a goaf), coal pillar recovery is necessary. Mining area coal pillars include section coal pillars, abandoned coal pillars, and main roadway coal pillars.

[0003] In existing technologies, the use of gob-side roadway retention technology can achieve the complete recovery of section coal pillars, while the use of short-wall mining face can achieve the partial recovery of main roadway coal pillars and unmined coal pillars. However, the overall process is complex and the recovery rate is not high. Summary of the Invention

[0004] This invention provides a method for the complete recovery of coal pillars in mining areas, which solves the defects of complex coal pillar recovery processes and low recovery rates in the prior art.

[0005] This invention provides a method for the complete recovery of coal pillars in a mining area, comprising:

[0006] While the current longwall face is being mined, the transport roadway between the current longwall face and the next longwall face is being supported.

[0007] After the current longwall face is completed, the hydraulic supports in the current longwall face are withdrawn using the withdrawal channel, and the withdrawal channel corresponding to the current longwall face is supported during the withdrawal process.

[0008] Using the current mining and support methods of the mining face, complete the mining of all mining faces and the support of the corresponding retreat channels;

[0009] Coal pillars are recovered using the mining area transport roadways and retreat channels.

[0010] According to an embodiment of the present invention, a method for completely recovering coal pillars in a mining area, wherein while mining the current longwall face, support is provided for the transport roadway between the current longwall face and the next longwall face, comprising:

[0011] While the current longwall face is being mined, the first support column is used to support the transport roadway between the current longwall face and the next longwall face.

[0012] According to an embodiment of the present invention, a method for completely recovering coal pillars in a mining area is provided, wherein, while the current mining face is being mined, a first support pillar is used to support the transport roadway between the current mining face and the next mining face, comprising:

[0013] After each preset distance of mining in the current mining face, the transport roadway of the mining face corresponding to that preset distance between the current mining face and the next mining face is supported by the first support column.

[0014] According to an embodiment of the present invention, a method for completely recovering coal pillars in a mining area, prior to supporting the haulage roadway between the current mining face and the next mining face using a first support pillar, the method further includes:

[0015] Based on the hysteresis pressure of the current longwall face, the support strength of the first support column is determined.

[0016] According to an embodiment of the present invention, a method for completely recovering coal pillars in a mining area, wherein the recovery of coal pillars is carried out using mining area transport roadways and retreat channels, includes:

[0017] The two roadways of the mining area transport roadway and the retreat passage are used as the coal pillar recovery working face to recover the main roadway coal pillar and the coal pillar that has been stopped from mining at the same time.

[0018] According to an embodiment of the present invention, a method for completely recovering coal pillars in a mining area, prior to supporting the haulage roadway between the current and next mining faces while mining the current mining face, the method further includes:

[0019] Construct a retreat channel and provide primary support for the retreat channel.

[0020] According to an embodiment of the present invention, a method for completely recovering coal pillars in a mining area, wherein constructing the retreat channel and providing primary support for the retreat channel includes:

[0021] The retraction channel is provided with primary support by a support structure, which includes a support beam and multiple pillars, with the multiple pillars supporting the support beam on the top plate of the retraction channel.

[0022] According to an embodiment of the present invention, a method for completely recovering coal pillars in a mining area is provided, wherein the hydraulic supports within the current mining face are withdrawn using a withdrawal channel, and the withdrawal channel corresponding to the current mining face is supported during the withdrawal process, including:

[0023] The retreat channel is used to retreat multiple hydraulic supports in the current mining face one by one, and during the retreat of each hydraulic support, the retreat channel corresponding to that hydraulic support is supported by a second support column.

[0024] A method for completely recovering coal pillars in a mining area according to an embodiment of the present invention, the method further comprising:

[0025] An isolation structure is installed between adjacent second support columns.

[0026] According to an embodiment of the present invention, a method for completely recovering coal pillars in a mining area is provided, wherein the first support pillar and the second support pillar are both pier pillars.

[0027] The method for complete recovery of coal pillars in a mining area provided by this invention supports the transport roadway between the current mining face and the next mining face while the current mining face is being mined. This eliminates the need to leave section coal pillars during the mining process. Furthermore, the hydraulic supports within the mining face are withdrawn using a withdrawal channel, and the withdrawal channel corresponding to the mining face is supported during the withdrawal process, thus preserving the withdrawal channel. Therefore, the complete recovery of coal pillars can be achieved using only the withdrawal channel and the mining area transport roadway, thereby improving the coal pillar recovery rate. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is one of the flowcharts illustrating the method for completely recovering coal pillars in a mining area provided in an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the layout of the coal pillars left in the longwall mining face according to an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the arrangement for supporting the transport roadway of the longwall mining face while mining the longwall face, provided by an embodiment of the present invention.

[0032] Figure 4 This is a schematic diagram of the layout for completing the mining of all mining faces and the support of the corresponding retreat channels, provided by an embodiment of the present invention.

[0033] Figure 5 This is the second flowchart illustrating the method for completely recovering coal pillars in a mining area provided in this embodiment of the invention.

[0034] Figure 6 This is the third flowchart illustrating the method for completely recovering coal pillars in a mining area provided in this embodiment of the invention;

[0035] Figure 7 This is a schematic diagram of the support structure at the retraction channel provided in an embodiment of the present invention;

[0036] Figure 8 This is a schematic diagram of the process of retracting the hydraulic support in the goaf provided in an embodiment of the present invention;

[0037] Figure 9 This is the fourth flowchart illustrating the method for completely recovering coal pillars in a mining area provided in this embodiment of the invention;

[0038] Figure 10 This is a schematic diagram of pressure relief near the retraction channel provided in an embodiment of the present invention.

[0039] Figure label:

[0040] 100. Section coal pillar;

[0041] 1. Mining area transport roadway; 2. Mining area return air roadway; 3. Mining area track roadway; 4. Main roadway coal pillar; 5. Stopped mining coal pillar; 6. Retreat passage;

[0042] 7. Support structure; 71. Support beam; 72. Column; 73. Anchor cable; 74. Second support column;

[0043] 8. Goaf; 81. Hydraulic support; 9. Transport roadway of longwall face; 10. First support pillar; 101. First pressure relief position; 102. Second pressure relief position;

[0044] A. Stop mining line. Detailed Implementation

[0045] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0046] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not 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 the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0047] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0048] In embodiments of the present 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," "on top of," and "over" 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.

[0049] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present 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.

[0050] The following is combined Figures 1-10 This invention describes a method for the complete recovery of coal pillars in a mining area, according to an embodiment of the present invention.

[0051] This invention proposes a method for the complete recovery of coal pillars in a mining area. Figure 1 An example of a flowchart illustrating one of the methods for completely recovering coal pillars in a mining area provided by an embodiment of the present invention is shown below. Figure 1 As shown, the method for completely recovering coal pillars in a mining area includes the following steps:

[0052] Step 101: While the current longwall face is being mined, support is provided for the longwall transport roadway 9 between the current longwall face and the next longwall face.

[0053] It is understandable that in existing technologies, such as Figure 2As shown, to ensure normal and safe production in the longwall face, safety coal pillars, namely section coal pillars 100, are left between sections of the longwall face. These section coal pillars 100 serve two purposes: firstly, to isolate the goaf 8 (which becomes the goaf 8 after the longwall face is mined out); and secondly, to ensure the stability of the section roadways (section roadways, i.e., the longwall face transport roadways 9, are formed between two adjacent goaf 8). However, the recovery of section coal pillars 100 is not considered, resulting in significant coal pillar losses and a low mine recovery rate. Furthermore, using goaf-side roadway retention technology to achieve complete recovery of section coal pillars is a complex process. In contrast, this embodiment of the invention supports the longwall face transport roadways 9 between longwall faces during the longwall face mining process, eliminating the need for section coal pillars 100.

[0054] It is understandable that the mining area has multiple longwall faces. While each longwall face is being mined, the transport roadway 9 between that longwall face and the next adjacent longwall face is being supported. Therefore, it is not necessary to leave section coal pillars 100 during the longwall face mining process, and thus there is no issue of recovering section coal pillars 100.

[0055] It is understandable that during the mining process of the longwall face, the 9th transport roadway of the longwall face is supported to reduce the dynamic pressure impact of the mining face on the roadways in the mining area.

[0056] Step 102: After the current longwall face is completed, the hydraulic support 81 in the current longwall face is withdrawn using the withdrawal channel 6, and the withdrawal channel 6 corresponding to the current longwall face is supported during the withdrawal process.

[0057] Understandably, once the longwall face is completed, it becomes goaf 8.

[0058] It is understandable that after the current mining face is completed, the hydraulic support 81 in the current goaf 8 is withdrawn using the withdrawal channel 6. In order to avoid deformation or support difficulties in the withdrawal channel 6 after the hydraulic support 81 is withdrawn, this embodiment of the invention supports the withdrawal channel 6 corresponding to the current goaf 8 during the withdrawal of the hydraulic support 81 in the current goaf 8, thereby preserving the withdrawal channel 6.

[0059] Step 103: Using the current mining and support methods of the mining face, complete the mining of all mining faces and the support of the corresponding retreat channel 6.

[0060] It is understandable that the mining area has multiple mining faces, which are set up sequentially along the mining direction. Therefore, mining of multiple mining faces and support of the corresponding retreat channel 6 are carried out sequentially along the mining direction.

[0061] It is understandable that, such as Figure 3 As shown in the illustration, this embodiment illustrates three working faces along the mining direction. Figure 3 From right to left, these are the first, second, and third longwall mining faces; firstly, as... Figure 3 As shown, the first longwall face is mined, and during the mining process, the transport roadway 9 between the first and second longwall faces is supported. After the first longwall face is mined, the first goaf is formed. Then, the hydraulic supports 81 in the first goaf are withdrawn using the withdrawal channel 6, and the withdrawal channel 6 corresponding to the first goaf is supported during the withdrawal process. Then, using the same mining and support method as the first longwall face, the mining of the second longwall face and the support of the withdrawal channel 6 corresponding to the second goaf are completed. Finally, using the same mining and support method as the first longwall face, the mining of the third longwall face and the support of the withdrawal channel 6 corresponding to the third goaf are completed, as shown. Figure 4 As shown, this completes the mining of all mining faces and the support of the corresponding retreat channel 6.

[0062] Step 104: Utilize the mining area transport roadway 1 and retreat passage 6 to recover the coal pillars.

[0063] Understandably, in existing technologies, a new roadway extending in the same direction as the mining area transport roadway 1 is excavated for the abandoned coal pillar 5. This newly excavated roadway serves as a recovery roadway, but it can only recover the abandoned coal pillar 5 between the newly excavated roadway and the mining area return airway 2, failing to achieve the complete recovery of the abandoned coal pillar 5. However, this embodiment of the invention utilizes the mining area transport roadway 1 and the withdrawal passage 6 as the recovery roadway, achieving the complete recovery of the abandoned coal pillar 5 and effectively improving the coal pillar recovery rate.

[0064] The method for complete recovery of coal pillars in mining areas provided by this invention supports the transport roadway 9 between the current mining face and the next mining face while mining the current mining face. This eliminates the need to leave section coal pillars 100 during the mining process. The hydraulic supports 81 in the mining face are withdrawn using the withdrawal channel 6, and the withdrawal channel 6 corresponding to the mining face is supported during the withdrawal process, thus preserving the withdrawal channel 6. Therefore, the complete recovery of coal pillars can be achieved using only the withdrawal channel 6 and the mining area transport roadway 1, thereby improving the coal pillar recovery rate.

[0065] It should be noted that the section coal pillars (recovered using the goaf retention technology), as well as the main roadway coal pillars and the stopped coal pillars (recovered using the shortwall mining method), need to be recovered separately using different processes, which leads to a complex overall recovery process. However, this invention does not require the retention of section coal pillars 100 during the mining process and does not involve the recovery of section coal pillars 100. The entire coal pillar can be recovered using only the retreat channel 6 and the mining area transport roadway 1, thus simplifying the recovery process and achieving a high recovery rate of coal pillars.

[0066] In one embodiment of the present invention, Figure 5 This is a second example of a flowchart illustrating the method for completely recovering coal pillars in a mining area provided by an embodiment of the present invention. Figure 5 As shown, prior to step 101, the method further includes the following steps:

[0067] Step 105: Construct the retreat channel 6 and provide primary support for the retreat channel 6.

[0068] It is understandable that the excavation of the retreat channel 6 will be carried out after the location of the retreat channel 6 is determined, so as to construct the retreat channel 6, and first-level support will be carried out immediately after the excavation to ensure the long-term preservation of the retreat channel 6.

[0069] It is understandable that, such as Figure 3 As shown, the coal mining area is equipped with mining area transport roadway 1, mining area return air roadway 2, and longwall face transport roadway 9 for mining raw coal. The retreat passage 6, mining area return air roadway 2, and mining area transport roadway 1 are arranged adjacent to each other and extend in the same direction. A longwall face transport roadway 9 is set between adjacent mining areas. The longwall face transport roadway 9 is perpendicular to the extension direction of the retreat passage 6 and is connected to the mining area transport roadway 1 and the retreat passage 6.

[0070] Understandably, the use of retreat channel 6 when the hydraulic support 81 of the underground coal mining face (retreating face) is withdrawn greatly shortens the withdrawal time of the coal mining face, realizes the rapid withdrawal of the coal mining face, and contributes to the high production and efficiency of the mine.

[0071] It should be noted that in the existing technology, the recovery of the abandoned coal pillar 5 requires the excavation of a new roadway as a recovery roadway, which is a dynamic pressure tunneling process, resulting in high tunneling costs and consequently high coal pillar recovery costs. However, the embodiment of this invention does not require the excavation of a new roadway; the complete recovery of the abandoned coal pillar 5 can be achieved by retaining the retreat channel 6, further reducing the high cost of coal pillar recovery.

[0072] It should be noted that, regarding the recovery method of coal pillars, another approach is to directly connect them to the main roadway or mining area roadway at the end of the working face. After the hydraulic supports 81 of the goaf 8 are moved in sequence, the roadway is filled in to retain the roadway. However, in this method, because the stopped coal pillar 5 is connected to the main roadway coal pillar 4, the mining area roadway is severely affected by dynamic pressure, making roadway support difficult and maintenance costs high. Furthermore, the roadway deformation is significant, and there is no spare roadway as a recovery roadway available for the working face to utilize, posing a high risk. In contrast, the embodiment of this invention can achieve the complete recovery of the stopped coal pillar 5 by retaining the withdrawal channel 6, and reduces the dynamic pressure impact of working face mining on the mining area roadway.

[0073] In one embodiment of the present invention, Figure 6 This is illustrated in the third flowchart of the method for completely recovering coal pillars in a mining area provided by an embodiment of the present invention. Figure 6 As shown, prior to step 105, the method further includes the following steps:

[0074] Step 106: Determine the position of the retreat channel 6 based on the position of the stop line A, and depressurize the working face side that is at a preset distance from the stop line A.

[0075] The stop line A, also known as the final mining line or the stop line, represents the boundary where mining ceases at the coal face. It's understandable that a coal mine face cannot mine indefinitely; it will stop due to geological conditions, roadway layout, production systems, etc. Therefore, a stop line A is needed to limit forward mining; mining stops at this point. A reasonable stop line A location should be a safe distance from the main roadway. This safe distance can be designed based on experience, such as 50-100 meters, thus forming a stop coal pillar 5 between stop line A and the main roadway. This stop coal pillar 5 ensures safety after the goaf 8 is closed. The goaf 8 is formed after the mining face within the mining area has been fully mined. Figure 4 The diagram shows three goaf areas 8. In addition, to maintain the stability of the main roadway or mining area roadway, a stop coal pillar 5 is also required at the working face.

[0076] It is understandable that when the working face is mined to the vicinity of the retreat passage 6, the dynamic pressure of the working face will affect the retreat passage 6 and the main roadway, causing deformation of the retreat passage 6 and the main roadway. As a result, the roadway at the retreat passage 6 and the main roadway cannot be used as a roadway for the recovery of the working face, and thus the recovery of the coal pillar cannot be achieved. Therefore, in order to reduce the impact of the dynamic pressure of the working face on the retreat passage 6 and the main roadway, the present invention implements pressure relief at a position near the mining side of the working face and at a predetermined distance from the stop line A, to avoid the impact of the dynamic pressure of the working face on the retreat passage 6 and the main roadway.

[0077] The method for completely recovering coal pillars in a mining area provided in this embodiment of the invention depressurizes the working face side at a preset distance from the stop-mining line A to achieve advance depressurization of the retreat channel 6. Primary support is provided during the construction of the retreat channel 6, and secondary support is provided for the retreat channel 6 during the retreat of the hydraulic support 81 in the goaf 8, thereby preserving the retreat channel 6. The retreat channel 6 and the mining area transport roadway 1 are then used as the recovery roadway to achieve complete recovery of the stop-mining coal pillar 5, thereby improving the recovery rate of the stop-mining coal pillar 5.

[0078] Furthermore, step 105 specifically includes the following:

[0079] The retreat passage 6 is supported by a support structure 7, which includes a support beam 71 and multiple columns 72. The multiple columns 72 support the support beam 71 on the top plate of the retreat passage 6.

[0080] It is understandable that, since the retreat channel 6 needs to be retained for a long time, the present invention uses a support structure 7 to provide active and passive support for the retreat channel 6.

[0081] Figure 7 A schematic diagram of the support structure at the retraction channel provided in an embodiment of the present invention is shown, such as... Figure 7 As shown, the support structure 7 includes a support beam 71 and multiple columns 72, which support the support beam 71 on the top plate of the retraction channel 6.

[0082] Understandably, after the excavation of the retreat channel 6, the support beam 71 is supported on the top plate of the retreat channel 6 by multiple pillars 72 to achieve the support of the retreat channel 6.

[0083] In this embodiment of the invention, the support beam 71 can be a π-shaped beam, and the column 72 is a single column. Each π-shaped beam is supported by multiple single columns to achieve support for the retraction channel 6.

[0084] It is understandable that the support beams 71 arranged in the retreat channel 6 are multiple and are spaced apart along the extension direction of the retreat channel 6; then after each section of the retreat channel 6 is excavated, the retreat channel 6 is supported by π-shaped beams and multiple individual pillars that cooperate with the π-shaped beams.

[0085] In another embodiment of the invention, the support structure 7 further includes an anchor cable 73 adapted to support the top plate of the retraction channel 6.

[0086] Understandably, in order to improve the support strength of the retreat channel 6, the top slab of the retreat channel 6 can be supported simultaneously by anchor cables 73.

[0087] The method for completely recovering coal pillars in the mining area provided in this embodiment of the invention can effectively improve the support strength of the retreat channel 6 by using anchor cables 73 in conjunction with single props and π-shaped beams for support.

[0088] In one embodiment of the present invention, step 101 includes the following:

[0089] While the current longwall face is being mined, the roof of the longwall transport roadway 9 between the current longwall face and the next longwall face is supported by the first support column 10.

[0090] Understandably, as the hydraulic support 81 moves during the current longwall mining, the first support column 10 is installed with a delay, and the roof of the longwall transport roadway 9 between the current longwall mining face and the next longwall mining face is supported by the first support column 10.

[0091] Furthermore, after each preset distance of mining in the current mining face, the transport roadway 9 of the mining face corresponding to the preset distance between the current mining face and the next mining face is supported by the first support column 10.

[0092] It is understandable that after each mining section of the current mining face, the first support column 10 is installed in a delayed manner to support the mining face transport roadway between the mining face and the next mining face.

[0093] In one embodiment of the present invention, step 101 further includes the following:

[0094] Based on the hysteresis pressure of the current longwall face, the support strength of the first support column is determined.

[0095] It is understandable that the first support column 10 can be a high-strength pier column. The support strength of the first support column 10 is determined according to the lag pressure of the current working face, so as to select a suitable pier column support strength; then, as the longwall mining face advances, the pier columns are installed in a delayed manner.

[0096] In another embodiment of the present invention, step 104 specifically includes the following:

[0097] Using the mining area transport roadway 1 and the retreat passage 6 as two roadways for coal pillar recovery working faces, the main roadway coal pillar 4 and the stopped coal pillar 5 are recovered simultaneously.

[0098] It is understandable that, such as Figure 3 As shown, the retreat channel 6, the mining area return airway 2, and the mining area transport roadway 1 are arranged sequentially and at intervals along the mining direction of the working face, thereby forming a stop-mining coal pillar 5 between the retreat channel 6 and the mining area return airway 2, and a main roadway coal pillar 4 between the mining area return airway 2 and the mining area transport roadway 1.

[0099] It is understandable that by using the mining area transport roadway 1 and the retreat passage 6 as the mining roadway, it is possible to achieve the complete recovery of the main roadway coal pillar 4 and the unmined coal pillar 5 in one go.

[0100] It should be noted that when recovering the main roadway coal pillar 4, if an intermediate empty roadway is encountered, it can be reinforced by means of single props, timber stacks, or backfilling. In this embodiment, the intermediate empty roadway can be the mining area track roadway 3 located between the mining area transport roadway 1 and the mining area return air roadway 2. The mining area transport roadway 1, the mining area track roadway 3, and the mining area return air roadway 2 extend in the same direction. A main roadway coal pillar 4 with a width of 25m can be formed between the mining area transport roadway 1 and the mining area track roadway 3, as well as between the mining area track roadway 3 and the mining area return air roadway 2. The width direction of the main roadway coal pillar 4 is parallel to the mining direction of the working face.

[0101] It should be noted that when all working faces in the mining area have been mined out, coal pillar recovery is carried out. If only the mining area transport roadway 1 and the mining area return air roadway 2 are used to recover the main roadway coal pillar 4, coal pillar 5 that has been stopped from mining will remain, and the complete recovery of all coal pillars will not be achieved. However, in this embodiment of the invention, by retaining the retreat channel 6 and utilizing the mining area transport roadway 1 and the retreat channel 6, the coal pillar 4 and the coal pillar 5 that have been stopped from mining can be completely recovered in one go, thereby improving the recovery rate and recovery efficiency.

[0102] In another embodiment of the present invention, step 102 specifically includes the following:

[0103] The retreat channel 6 is used to retreat multiple hydraulic supports 81 in the current mining face one by one, and during the retreat of each hydraulic support 81, the retreat channel 6 corresponding to that hydraulic support 81 is provided with secondary support through the second support column 74.

[0104] It is understandable that the hydraulic support 81 of the goaf 8 is withdrawn using the withdrawal channel 6, and secondary support is provided on the side of the withdrawal channel 6 close to the goaf 8 through the second support column 74 during the withdrawal process.

[0105] It is understandable that during the retraction process of the hydraulic support 81 in the goaf 8 using the retraction channel 6, the retraction channel 6 is supported by the second support column 74, and the second support column 74 is located on the side of the retraction channel 6 close to the goaf 8.

[0106] Understandably, during the retraction of hydraulic support 81, a second support column 74 is installed behind it to support it, thereby preserving the retraction channel 6.

[0107] In this embodiment of the invention, the second support column 74 can be a high-strength pier column to reinforce the support of the retraction channel 6.

[0108] It is understandable that during the mining process, strong pillars are used to replace section coal pillar 100 to recover section coal pillar 100. Strong pillars are also installed in the retreat channel 6. The strong support of the pillars is used to retain the retreat channel 6, thereby using the retreat channel 6 and the mining area transport roadway 1 to recover all the main roadway coal pillar 4 and the stopped coal pillar 5.

[0109] Understandably, both the first support column 10 and the second support column 74 adopt the form of strong pier support to reduce the cumbersome problems caused by existing different processes (concrete wall, high water content material wall, U-shaped steel, etc.).

[0110] Furthermore, since there are multiple hydraulic supports 81 within each goaf 8, at the end of the working face mining phase, it is necessary to relocate the multiple hydraulic supports 81 within the goaf 8 through the retreat channel 6. This specifically includes the following:

[0111] The multiple hydraulic supports 81 in the goaf 8 are withdrawn one by one using the withdrawal channel 6, and the withdrawal channel 6 corresponding to each hydraulic support 81 is provided with secondary support through the second support column 74 during the withdrawal process.

[0112] Understandable. Figure 8 A schematic diagram illustrating the retraction process of the hydraulic support in the goaf provided in an embodiment of the present invention is shown, such as... Figure 8 As shown, the multiple hydraulic supports 81 in the goaf 8 are respectively the first hydraulic support, the second hydraulic support, the third hydraulic support, ... the Nth hydraulic support, which are arranged side by side along the extension direction of the withdrawal channel 6. The first hydraulic support is withdrawn using the withdrawal channel 6. During the withdrawal of the first hydraulic support, the position corresponding to the first hydraulic support in the withdrawal channel 6 is supported by the piers to complete the withdrawal of the first hydraulic support. Then, the second hydraulic support, the third hydraulic support, ... the Nth hydraulic support are withdrawn in the same way as the first hydraulic support, and are supported by the piers. Thus, after the multiple hydraulic supports 81 in the goaf 8 are withdrawn, the withdrawal channel 6 can be preserved through the support of the piers.

[0113] It is understandable that when each hydraulic support 81 is withdrawn, a temporary support frame can be set up first on the side of the withdrawal channel 6 near the goaf 8 and at the position that cooperates with the hydraulic support 81. After the hydraulic support 81 is withdrawn from the goaf 8 to the withdrawal channel 6, a second support column 74 is arranged at the position of the support frame. Figure 8 The diagram shows that one hydraulic support 81 has been retracted into the retraction channel 6, and the next hydraulic support 81 is about to be retracted.

[0114] In another embodiment of the present invention, the support resistance of the second support column 74 is greater than or equal to the support resistance of the hydraulic support 81 in the goaf 8.

[0115] It is understandable that when the hydraulic support 81 is withdrawn within the goaf 8, and the withdrawal channel 6 is supported by the second support column 74, the support resistance of the second support column 74 within the withdrawal channel 6 should not be lower than the support resistance of the hydraulic support 81 within the goaf 8. Here, the support resistance of the hydraulic support 81 within the goaf 8 refers to the support resistance of all hydraulic supports 81 within each goaf 8. Correspondingly, the support resistance of the second support column 74 within the withdrawal channel 6 refers to the support resistance of all second support columns 74 within the withdrawal channel 6 corresponding to that goaf 8.

[0116] Understandably, the second support column 74 is a pier column, and the pier column can be made of concrete. The strength grade of concrete is divided according to the standard compressive strength, which is called the grade. It can be divided into 19 grades. The cross-sectional area and spacing of the pier column are different depending on the strength grade of concrete selected. In actual implementation, the cross-sectional area of ​​the pier column and the distance between adjacent pier columns can be adjusted according to the selected concrete strength to ensure that the support resistance of the second support column 74 in the retreat channel 6 is not lower than the support resistance of the hydraulic support 81 in the goaf 8.

[0117] In another preferred embodiment of the present invention, step 102 specifically includes the following:

[0118] An isolation structure is installed between adjacent second support columns 74.

[0119] It is understandable that the multiple hydraulic supports 81 in the goaf 8 are withdrawn one by one. During the withdrawal process of each hydraulic support 81, the withdrawal channel 6 corresponding to the hydraulic support 81 is supported by the second support column 74, and an isolation structure is set between the current first support column 10 and the previous first support column 10.

[0120] It is understandable that, for each hydraulic support 81 withdrawn from the goaf 8, a second support column 74 is installed on the side of the withdrawal channel 6 closest to the goaf 8 and corresponding to the hydraulic support 81. Then, an isolation net is installed between the current first support column and the previous first support column that supported the withdrawal channel 6 during the withdrawal of the previous hydraulic support 81. The isolation structure can be an isolation net.

[0121] In another embodiment of the invention, Figure 9 Example four illustrates a flowchart of the method for completely recovering coal pillars in a mining area provided by an embodiment of the present invention, as follows: Figure 9 As shown,

[0122] Prior to step 106, the method further includes the following steps:

[0123] Step 107: Determine the position of the stop mining line A based on the width of the stop mining pillar 5.

[0124] Understandably, based on experience, a stop coal pillar 5 with a width of 50m to 100m is generally left. The stop coal pillar 5, located furthest from the main roadway along the working face mining direction, has the least impact on the main roadway. Therefore, the end face of the stop coal pillar 5 closest to the working face is taken as the stop line A, which means choosing the position with the lowest impact on the main roadway as the stop line A.

[0125] It is understandable that, for example, if the width of the coal pillar 5 to be stopped is 50m, then the position 50m away from the return airway of the mining area along the mining direction of the working face is the stop line A. Therefore, the position of the stop line A can be determined according to the width of the coal pillar 5 to be stopped.

[0126] In one embodiment of the present invention, step 106 further includes the following:

[0127] Multiple pressure relief positions are selected on the working face side at a preset distance from the stop line A; hydraulic fracturing is performed on the multiple pressure relief positions to complete the pressure relief on the working face side.

[0128] Understandably, in order to reduce the impact of dynamic pressure on the retreat passage 6 and the main roadway, hydraulic fracturing and other methods are used to relieve pressure on the goaf side.

[0129] Understandable, Figure 10 A schematic diagram illustrating pressure relief near the retraction channel provided in an embodiment of the present invention is shown, such as... Figure 10 As shown in the embodiment of the present invention, two pressure relief positions are set on the goaf side, namely the first pressure relief position 101 and the second pressure relief position 102. The distance L1 between the first pressure relief position 101 and the stop line A in the working face mining direction is 11m, and the distance H1 between the first pressure relief position 101 and the roof of the retreat channel 6 in the vertical direction is 18m. The distance L2 between the second pressure relief position 102 and the stop line A in the working face mining direction is 13m, and the distance H2 between the second pressure relief position 102 and the roof of the retreat channel 6 in the vertical direction is 32m. Since there are hard roofs of different layers above the retreat channel 6, the pressure relief position is selected according to the lithology and hardness of the strata. In this embodiment, the roof is accelerated to collapse in layers through two pressure relief boreholes.

[0130] It should be noted that in other implementations, the depressurization point can be designed as one or more as needed, and the setting position can also be adjusted adaptively as needed.

[0131] In one embodiment of the present invention, the method for completely recovering coal pillars in a mining area may specifically include the following:

[0132] First, based on the width of the stop coal pillar 5, determine the position of the stop line A;

[0133] Secondly, based on the location of the stop line A, the location of the retreat channel 6 is determined, and multiple pressure relief locations are selected on the working face side with a preset distance from the stop line A. Hydraulic fracturing is used to fracture the multiple pressure relief locations to complete the pressure relief on the working face side.

[0134] Third, excavation of retreat passage 6 was carried out to construct retreat passage 6, and primary support was provided for retreat passage 6.

[0135] Fourth, multiple longwall faces are mined one by one. During the mining process of each longwall face, the transport roadway 9 between the current longwall face and the next adjacent longwall face is supported. After the mining of each longwall face is completed, the hydraulic supports 81 in the corresponding goaf 8 are withdrawn. At the same time, during the withdrawal of the hydraulic supports 81 in the goaf 8, the withdrawal channel 6 corresponding to the goaf 8 is provided with secondary support, thereby preserving the withdrawal channel 6. After the mining of all coal areas is completed, the withdrawal channels 6 corresponding to all goaf 8 are preserved.

[0136] Understandable, Figure 4 The diagram shows three longwall faces in a mining area: the first longwall face, the second longwall face, and the third longwall face. The corresponding retreat channels 6, along the coal pillar recovery direction, are respectively the retreat channel for face 01, the retreat channel for face 02, and the retreat channel for face 03. First, the first longwall face is mined. During the mining process, the first support column 10 supports the transport roadway 9 between the first and second longwall faces. After mining, the first goaf is formed. The hydraulic support 81 within the first goaf is retreated through the retreat channel for face 01. During the retreat, the retreat channel for face 01 receives secondary support from the second support column 74. Then, the mining of the second and third longwall faces, as well as the secondary support of the retreat channels for faces 02 and 03, are completed in the same manner. Thus, after the mining of the three longwall faces is completed, the three retreat channels 6 corresponding to the three goafs 8 are all retained.

[0137] Fifth, after all working faces in the mining area have been mined, the mining area transport roadway 1 and the withdrawal passage 6 are used as two roadways for coal pillar recovery working faces to fully recover the main roadway coal pillar 4 and the stopped coal pillar 5 in one go.

[0138] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of fully recovering a coal pillar of a mining area, characterized by, The method comprises the following steps: constructing a retreat channel and supporting the retreat channel; supporting the mining face haulage way between the current mining face and the next mining face while mining the current mining face; after the mining of the current mining face is completed, retreating the hydraulic support in the current mining face by using the retreat channel, and supporting the retreat channel corresponding to the current mining face during the retreat process; using the mining and supporting mode of the current mining face to complete the mining of all mining faces and the support of the corresponding retreat channels; using the mining area haulage way and the retreat channel as two crossheading of the coal pillar recovery working face to simultaneously recover the main roadway coal pillar and the stop mining coal pillar; wherein the construction of the retreat channel and the primary support of the retreat channel comprises: supporting the retreat channel by a supporting structure, the supporting structure comprising a support beam and a plurality of support columns, and the plurality of support columns supporting the support beam on the roof of the retreat channel; the supporting of the mining face haulage way between the current mining face and the next mining face while mining the current mining face comprises: after each mining of a preset distance of the current mining face, supporting the mining face haulage way corresponding to the preset distance between the current mining face and the next mining face by a first support column; the retreat of the hydraulic support in the current mining face by using the retreat channel and the support of the retreat channel corresponding to the current mining face during the retreat process comprises: retreating the plurality of hydraulic supports in the current mining face one by one by using the retreat channel, and supporting the retreat channel corresponding to each hydraulic support by a second support column during the retreat process of the hydraulic support.

2. The method of fully recovering a coal pillar according to claim 1, characterised in that, Before the supporting of the mining face haulage way between the current mining face and the next mining face by the first support column, the method further comprises: determining the supporting strength of the first support column based on the lag pressure of the current mining face.

3. The method of fully recovering a coal pillar according to claim 1, wherein, The method further comprises: setting an isolation structure between adjacent second support columns.

4. The method of fully recovering a coal pillar according to claim 1, wherein, The first support column and the second support column are both pier columns.

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