A method for mining a coal seam having a variable thickness

Abstract

The application discloses a mining method for a coal seam with variable thickness, which comprises the following steps: excavating a connecting lane in a critical area of a first coal seam and a second coal seam in advance; mining the first coal seam by a full-height mining method; when a working face advances to a set distance from the connecting lane, disconnecting a connection between an end support and a transfer machine; continuously advancing the working face and supporting an area between the end support and the transfer machine; when the working face advances to a position opposite to the connecting lane, transporting and arranging a rear scraper conveyor behind the working face support through the connecting lane; moving a tail of the transfer machine backward and connecting the tail with the end support to form a top coal caving device; and mining the second coal seam by a top coal caving method. The mining method can realize mining of a coal seam with variable thickness, and avoids a series of problems, such as coal wall spalling, low resource recovery rate, high mining cost, large workload and the like, in mining of the coal seam with variable thickness in the prior art.

Description

Technical Field

[0001] This invention relates to the field of coal seam mining technology, and more specifically, to a method for mining coal seams with varying thickness. Background Technology

[0002] During underground mining, some coal seams exhibit significant variations in thickness along the mining direction, meaning they have a large coefficient of variation. In some cases, the thickest part of the seam can be more than twice the thickness of the thinnest part. Currently, the most common mining methods for these variable coal seams include fully mechanized mining (one-pass full-height mining), top coal caving, and multi-stage mining with multiple sets of equipment. However, these methods suffer from problems such as coal wall spalling, low resource recovery rates, high mining costs, and heavy workloads, and cannot fully meet the needs of mining coal seams with varying thicknesses. Summary of the Invention

[0003] The present invention aims to at least partially solve one of the technical problems in the related art.

[0004] Therefore, this invention proposes a method for mining coal seams with varying thickness. This method enables the mining of coal seams with significant variations in thickness, avoiding a series of problems in existing technologies for mining such coal seams with varying thickness, such as coal wall spalling, low resource recovery rate, high mining cost, and large workload.

[0005] The present invention discloses a method for mining coal seams with varying thickness, wherein the varying thickness coal seam includes a first coal seam and a second coal seam arranged sequentially in the mining direction, the first coal seam being thinner than the second coal seam, and the mining method includes the following steps:

[0006] S1: A connecting roadway is pre-excavated in the critical area between the first coal seam and the second coal seam;

[0007] S2: The first coal seam is mined by mining the full height in one go;

[0008] S3: When the working face advances to a set distance from the connecting roadway, disconnect the end support and the transfer machine;

[0009] S4: Continue to advance the working face and provide support for the area between the end support and the transfer machine;

[0010] S5: When the working face is advanced to the position opposite the connecting roadway, the rear scraper conveyor is transported to the rear of the working face support through the connecting roadway and arranged.

[0011] S6: Move the tail of the transfer machine backward and connect it to the end support to construct a top coal caving device;

[0012] S7: The second coal seam is mined by top coal caving.

[0013] In some embodiments, in step S4, the area between the end support and the transfer machine is supported by temporary support, the form of which includes at least one of the following: point pillars, timber stacks, and single hydraulic props.

[0014] In some embodiments, in step S5, the working face support includes a central hydraulic support and a transition support, and the rear scraper conveyor is connected to the rear of the central hydraulic support and the transition support.

[0015] In some embodiments, the mining equipment for full-height mining in one operation includes a front scraper conveyor, which is located in front of the working face support and is connected to the transfer machine via an end-discharge arrangement or a cross-side-discharge arrangement.

[0016] In some embodiments, the front scraper conveyor is connected to the transfer machine via an end-discharge arrangement, and the rear scraper conveyor is connected to the transfer machine via a cross-side-discharge arrangement after being transported to the rear of the working face support through the connecting tunnel.

[0017] In some embodiments, the front scraper conveyor is connected to the transfer machine via a cross-side unloading arrangement, and step S5 further includes the following step:

[0018] S51: The middle trough and tail drive unit of the rear scraper conveyor are transported to the rear of the working face support via the connecting tunnel;

[0019] S52: Disconnect the connection between the middle trough and the transition trough of the front scraper conveyor, and then move the transition trough and the drive unit of the front scraper conveyor backward and connect them with the middle trough of the rear scraper conveyor to construct the complete rear scraper conveyor.

[0020] S53: The end-discharge transition trough and drive unit are transported via the connecting tunnel to the front scraper conveyor and connected to the middle trough of the front scraper conveyor to construct a new front scraper conveyor.

[0021] In some embodiments, step S6 further includes the following step:

[0022] The transport trough of a portion of the transfer machine is conveyed via the connecting tunnel to the front side of the tail of the transfer machine to fill the missing part between the front scraper conveyor and the rear scraper conveyor.

[0023] In some embodiments, during the top coal caving process, a single-row advanced support, a rear advanced support, and a front advanced support are arranged sequentially along the mining direction in the transport roadway serving the working face. The single-row advanced support is located on the non-production side of the transfer machine and is connected to the rear advanced support.

[0024] The construction of the top coal caving equipment includes the following steps:

[0025] The single-row advanced support is transported via the connecting lane to the non-production side of the transport lane and connected to the rear of the rear advanced support.

[0026] In some embodiments, an auxiliary transport lane is provided on the side of the transport lane, and the auxiliary transport lane is connected to the transport lane through a connecting lane. The single-row advanced support and the rear scraper conveyor are transported through the auxiliary transport lane and the connecting lane.

[0027] In some embodiments, the working surface is provided with a plurality of central hydraulic supports, the plurality of central hydraulic supports are arranged sequentially along the extension direction of the working surface, and transition supports are provided at both ends of the plurality of central hydraulic supports.

[0028] The central hydraulic support includes a telescopic insert plate and a tail beam. During the process of mining a full height in one go, the telescopic insert plate retracts and the tail beam is lowered to its lowest position.

[0029] The height adjustment range of the central hydraulic support is determined in the following way:

[0030] Using the maximum coal thickness revealed by the borehole diagram of the working face as a reference, a parameter is then set upwards on the reference as the maximum height adjustment of the central hydraulic support;

[0031] The minimum height adjustment of the central hydraulic support is determined based on the well drilling method and the actual situation of the existing equipment.

[0032] Beneficial effects: The coal seam mining method of the present invention can realize the mining of coal seams with large variations in thickness, avoiding a series of problems in the prior art for mining such coal seams with varying thickness, such as coal wall spalling, low resource recovery rate, high mining cost, and large workload. Attached Figure Description

[0033] Figure 1 This is a side view of the support and transportation system according to an embodiment of the present invention.

[0034] Figure 2 This is a top view schematic diagram of the support and transportation system according to an embodiment of the present invention.

[0035] Figure 3This is a schematic diagram of the working face equipment layout during a single full-height mining process according to an embodiment of the present invention.

[0036] Figure 4 This is a schematic diagram illustrating the process of switching from a full-height mining face to a top-coal caving face in an embodiment of the present invention.

[0037] Figure 5 This is a schematic diagram of the working face equipment layout during the top coal caving process according to an embodiment of the present invention.

[0038] Figure label:

[0039] 1-Transfer conveyor; 2-Crusher; 3-Front advance support; 4-Rear advance support; 5-First jack; 6-Second jack; 7-Single row advance support; 8-End support; 9-Front scraper conveyor; 10-Rear scraper conveyor; 11-Transition support; 12-Transport roadway; 13-Connecting roadway; 14-Auxiliary transport roadway; 15-Middle hydraulic support; 16-Coal mining machine; 17-Return airway; 18-One-time full-height conveyor. Detailed Implementation

[0040] 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.

[0041] This invention is based on the inventor's discoveries and understanding of the following facts and problems:

[0042] For coal mining faces where the coal seam thickness increases unidirectionally in the mining direction and the coefficient of variation is large (the maximum coal thickness is about twice the minimum coal thickness), the main mining methods currently used are fully mechanized longwall mining, face relocation and face replacement, and fully mechanized longwall top coal caving mining. However, each of these three methods has its own drawbacks.

[0043] (1) Full-length fully mechanized mining process: In order to extract as much top coal as possible, the maximum height adjustment of the hydraulic support often needs to meet the mining requirements of the maximum coal thickness. This makes the contradiction between improving the resource recovery rate and the existing hydraulic support technology level prominent. That is, to ensure the resource recovery rate, it is necessary to increase the maximum height adjustment of the hydraulic support, which will lead to the following problems: 1. When the mining height is large, the side spalling phenomenon is serious, and large pieces of coal can enter the front and inside of the support pedestrian passage. Moreover, the distance between the ends of the support beam is too large, which is prone to safety problems such as roof fall and support collapse; 2. When the coal thickness is small, the hydraulic support maintains a low posture for a long time, and the phenomenon of breakage of the ear plate of the shield beam balance jack is frequent.

[0044] (2) The mining method of relocating and changing the working face mainly involves mining the working face in two sections and relocating and changing the working face in the middle. This method requires the purchase of two sets of working face three-machine (hydraulic support, coal mining machine, scraper conveyor) equipment, and requires two cutting and tunneling operations, two working face equipment installation operations, and two working face equipment removal operations. In addition, a sufficiently wide coal pillar needs to be left between the first section stop line and the second section working face cutting to ensure the safety of the tunneling process.

[0045] The disadvantages of the face relocation and replacement process are: 1. Equipment investment doubles; 2. The workload of cutting, excavating, installing and removing equipment doubles; 3. A sufficiently wide coal pillar needs to be left between the stop line of the first working face and the cut of the second working face, resulting in a large amount of coal that cannot be mined, which seriously affects economic benefits.

[0046] (3) The disadvantages of the fully mechanized top coal caving process are: 1. The working face advances slowly; 2. The top coal recovery rate is generally between 65% and 80%, while the coal recovery rate of machine mining can reach 98%. The comprehensive resource recovery rate of the fully mechanized top coal caving process is significantly lower than that of the fully mechanized one-time full-height mining process; 3. Under the condition of small mining-to-caving ratio, the difficulty of coal caving increases and the gangue content of the fallen coal is high.

[0047] Based on the above, this invention proposes a method for mining coal seams with varying thickness.

[0048] It should be noted that the mining method in this embodiment of the invention is based on a matching top coal caving support and transportation system.

[0049] like Figure 1 and Figure 2 As shown, the top coal caving face support and transportation system (hereinafter referred to as the top coal caving support and transportation system) of this embodiment of the invention includes a transfer machine 1, a crusher 2, a front advance support 3, a rear advance support 4, a first jack 5, a second jack 6, a single-row advance support 7, an end support 8, a front scraper conveyor 9, a rear scraper conveyor 10, and multiple transition supports 11. Both the first jack 5 and the second jack 6 can be pushing jacks.

[0050] The crusher 2 is located in the middle of the transfer conveyor 1. For example, the transfer conveyor 1 can be located in the transport roadway 12 of the working face and extend along the transport roadway 12, specifically along... Figure 1 Extending in the front-to-back direction, the crusher 2 can be mounted in the middle position of the transfer conveyor 1 in the front-to-back direction. In use, the transfer conveyor 1 can transfer coal mined from the working face to the belt conveyor, while the crusher 2 can perform crushing operations on coal and other blocky structures.

[0051] Both the front advance support 3 and the rear advance support 4 can straddle the transfer machine 1. The front advance support 3 can be close to the head of the transfer machine 1, and the rear advance support 4 can be close to the tail of the transfer machine 1. The crusher 2 is located between the front advance support 3 and the rear advance support 4.

[0052] For example, both the front advance support 3 and the rear advance support 4 can be roughly U-shaped. Both the front advance support 3 and the rear advance support 4 are located in the transport tunnel 12 and span across the top of the transfer machine 1. The front advance support 3 can be located in front of the rear advance support 4. The front advance support 3 and the rear advance support 4 can provide advance protection for the transfer machine 1 and the crusher 2.

[0053] The first jack 5 is connected between the front advance support 3 and the crusher 2, and the second jack 6 is connected between the crusher 2 and the rear advance support 4. For example, as Figure 1 and Figure 2 As shown, there can be two first jacks 5 and two second jacks 6. The two first jacks 5 can be located on the left and right sides of the transfer machine 1, respectively, and both first jacks 5 are connected between the front support 3 and the crusher 2. The two second jacks 6 can also be located on the left and right sides of the transfer machine 1, respectively, and both second jacks 6 are connected between the rear support 4 and the crusher 2.

[0054] A single-row advance support 7 is located on the non-production side of the transfer conveyor 1 and connected to the rear advance support 4. The rear advance support 4 is located between the crusher 2 and the single-row advance support 7. For example, as... Figure 1 and Figure 2 As shown, compared to the front advance support 3 and the rear advance support 4, the single-row advance support 7 can be a single-row support. The non-production side of the transfer machine 1 can be the right side of the transfer machine 1. The single-row advance support 7 can be located only on the right side of the transfer machine 1 and connected to the rear of the rear advance support 4. In use, the single-row advance support 7 can move synchronously with the rear advance support 4 in the front-back direction.

[0055] The end support 8 includes a third jack, which is connected to the tail of the transfer machine 1. The tail of the transfer machine 1 can be the rear end of the transfer machine 1, which can be equipped with a pushing beam or other structures. The third jack can be installed at the base of the end support 8 and can be connected to the pushing beam or other structures of the transfer machine 1.

[0056] The rear scraper conveyor 10 is located between the front scraper conveyor 9 and the end support 8. The front scraper conveyor 9 is connected to the transfer conveyor 1, and the rear scraper conveyor 10 is connected to the transfer conveyor 1. For example, as Figure 2As shown, both the front scraper conveyor 9 and the rear scraper conveyor 10 can be located within the working surface and extend in the left-right direction, with the front scraper conveyor 9 positioned in front of the rear scraper conveyor 10. The front scraper conveyor 9 can be directly connected to the transfer conveyor 1 via an end-discharge arrangement. There is no rigid connection between the front scraper conveyor 9 and the transfer conveyor 1, meaning the front scraper conveyor 9 can move independently of the transfer conveyor 1. The rear scraper conveyor 10 can be connected to the transfer conveyor 1 via a cross-side-discharge arrangement, allowing the rear scraper conveyor 10 and the transfer conveyor 1 to move synchronously.

[0057] Multiple transition supports 11 are provided between the front scraper conveyor 9 and the rear scraper conveyor 10. Each transition support 11 includes a fourth jack and a connecting piece. The fourth jack is connected to the front scraper conveyor 9, and the connecting piece is connected to the rear scraper conveyor 10.

[0058] For example, such as Figure 2 As shown, there can be three transition supports 11. In other embodiments, there can also be two, four, or other numbers of transition supports 11. The three transition supports 11 can be arranged at intervals in the left-right direction, and in the front-back direction, the three transition supports 11 can be located between the front scraper conveyor 9 and the rear scraper conveyor 10. The base of each transition support 11 can be equipped with a fourth jack, the front end of which can be connected to the front scraper conveyor 9, thereby meeting the need for pushing the front scraper conveyor 9 forward. The top beam of each transition support 11 can be designed as a single beam.

[0059] The connecting parts can be jacks, chains, etc. The base of each transition bracket 11 can be connected to the rear scraper conveyor 10 through the connecting parts, so that the rear scraper conveyor 10 can be driven to move forward when the transition bracket 11 moves forward.

[0060] The mining method in this embodiment of the invention is also based on a matching full-height support and transportation system (hereinafter referred to as the full-height support and transportation system).

[0061] like Figure 3 As shown, the single-mining full-height support and transportation system of this invention mainly includes a single-mining full-height conveyor 18, a working face support, an end support 8, and a transfer machine 1. The working face support mainly includes multiple central hydraulic supports 15 and transition supports 11 located at both ends of the multiple central hydraulic supports 15. The single-mining full-height conveyor 18 is located in front of the working face support, and the end support 8 and the transfer machine 1 are both located within the transportation roadway 12.

[0062] It should be noted that the variant coal seam of the present invention mainly refers to a coal seam that gradually thickens in the mining direction. The variant coal seam can be divided into a first coal seam and a second coal seam according to the different thicknesses in the mining direction. The first coal seam can be half the thickness of the second coal seam, and the first coal seam should be mined before the second coal seam.

[0063] Based on the above-mentioned support and transportation system, the mining method for coal seams with varying thickness according to this invention includes the following steps:

[0064] S1: A connecting roadway 13 is pre-excavated in the critical area between the first and second coal seams. For example, as... Figure 3 As shown, an auxiliary haulage roadway 14 can be provided on the side of the haulage roadway 12. Before the working face is officially mined, the critical area between the first coal seam and the second coal seam can be determined first. The critical area is the junction of the first coal seam and the second coal seam. Then, a connecting roadway 13 can be excavated at the location of the critical area. The connecting roadway 13 extends roughly in the left and right direction and connects the haulage roadway 12 and the auxiliary haulage roadway 14.

[0065] S2: The first coal seam is mined using a full-height mining method. For example, after the aforementioned full-height mining support and transportation system is installed, the first coal seam can be mined using a fully mechanized full-height mining method. Specifically, the coal cut by the coal mining machine 16 can be transported to the transfer conveyor 18 via a full-height mining conveyor, and then directly transported to the belt conveyor and out of the working face via the transfer conveyor 1. The original central hydraulic support 15 and transition support 11 can provide support for the roof of the working face roadway, while the original front advance support 3, rear advance support 4, and end support 8 can provide support for the advance section and the triangular area.

[0066] S3: When the working face advances to a set distance from the connecting roadway 13, disconnect the end support 8 and the transfer machine 1.

[0067] For example, such as Figure 4 As shown, the set distance can be a space sufficient to accommodate subsequent single-row advance supports 7, rear scraper conveyors 10, and other equipment, or it can be considered part of the transport roadway 12. When the working face advances to a position at a set distance from the connecting roadway 13, the connection between the end support 8 and the transfer machine 1 can be manually disassembled, so that the end support 8 will not move synchronously with the transfer machine 1 during the subsequent advancement of the working face.

[0068] S4: Continue advancing the working face and provide support for the area between the end support 8 and the transfer machine 1. For example, after the connection between the end support 8 and the transfer machine 1 is removed, the working face can continue to advance. During the advancement of the working face, due to the lack of timely support from the end support 8, the distance between the tail of the transfer machine 1 and the end support 8 will gradually increase, resulting in a gap between them. At this time, it is necessary to provide timely support for the roof between them to prevent the roof from collapsing, thereby ensuring the safety of the mining operation.

[0069] S5: When the working face advances to the point where it is opposite to the connecting roadway 13, the rear scraper conveyor 10 is transported and arranged behind the working face support via the connecting roadway 13. For example, as Figure 5 As shown, when the head of the coal mining machine 16 in the working face is directly opposite the connecting roadway 13 in the left-right direction, the rear scraper conveyor 10 used for top coal caving can be transported to the rear of the working face support through the auxiliary transport roadway 14 and the connecting roadway 13 to complete the installation and arrangement of the rear scraper conveyor 10.

[0070] It should be noted that, since the transfer machine 1 and the end support 8 are separated in advance, the components of the rear scraper conveyor 10 can be transported through the gap between the transfer machine 1 and the end support 8, which facilitates the installation and arrangement of the rear scraper conveyor 10.

[0071] S6: Move the tail of the transfer conveyor 1 backward and connect it to the end support 8 to construct a top coal caving device. For example, after the rear scraper conveyor 10 is installed and arranged, the tail of the transfer conveyor 1 can be moved backward and reconnected to the end support 8. If the length of the transfer conveyor 1 is insufficient, it can be supplemented by adding a transport trough.

[0072] It should be noted that the top coal caving equipment can be understood as the aforementioned top coal caving support and transportation system, and the aforementioned full-height conveyor 18 for one-time full-height mining can be constructed as a front scraper conveyor 9, thereby meeting the transportation needs of the coal mined by the front coal mining machine 16.

[0073] S7: The second coal seam is mined by top coal caving. Specifically, such as... Figure 5 As shown, after the aforementioned full-height support and haulage system is completely converted into a top-coal caving support and haulage system, the second coal seam can be mined through the converted top-coal caving support and haulage system. During the mining process, the coal cut by the coal mining machine 16 can be transported to the transfer conveyor 1 via the front scraper conveyor 9, while the coal falling from the roof can be transported to the transfer conveyor 1 via the rear scraper conveyor 10. The coal on the transfer conveyor 1 can be transferred to the belt conveyor and finally transported out of the working face.

[0074] After cutting to a certain depth, the front scraper conveyor 9 can be moved forward using the pushing jacks of the multiple central hydraulic supports 15 on the working face and the fourth jack of the aforementioned transition support 11. Then, the forward movement of the aforementioned front advance support 3 can be achieved using the first jack 5. Finally, the overall forward movement of the transfer machine 1, crusher 2, and rear scraper conveyor 10 can be achieved using the first jack 5, the second jack 6, the third jack, etc.

[0075] The coal seam mining method of the present invention, which is characterized by varying coal seam thickness, realizes segmented mining of the coal seam. The first coal seam can be mined using a more suitable full-height mining method, while the second coal seam, being thicker, can be mined using a more suitable top coal caving method. This avoids the problems of coal wall spalling and low resource recovery rate caused by using only a single mining method in the prior art.

[0076] Secondly, the transformation from a full-height support and transportation system to a top coal caving support and transportation system can be achieved by directly adjusting the original support and transportation system. Compared with the relocation method used in the existing technology, the overall operation process is simpler, more efficient, and cheaper, and it also greatly reduces the overall labor intensity, which is conducive to ensuring the overall mining efficiency.

[0077] In some embodiments, in step S4, the area between the end support 8 and the transfer machine 1 is supported by temporary support. The form of temporary support includes at least one of the following: point pillar, timber stack, or single hydraulic prop.

[0078] Specifically, after the transfer machine 1 and the end support 8 are disconnected, the roof in front of the end support 8 can be temporarily supported in a timely manner as the working face advances by one step, thereby realizing the support as the working face moves and fully ensuring the safety of the mining.

[0079] In some embodiments, in step S5, the working face support includes a central hydraulic support 15 and a transition support 11, and the rear scraper conveyor 10 is connected to the rear of the central hydraulic support 15 and the transition support 11. For example, after the rear scraper conveyor 10 is assembled at the rear of the working face support, it can be connected to the central hydraulic support 15 and the transition support 11 in the working face support via chains, jacks, etc. This allows the rear scraper conveyor 10 to move forward as the working face support moves.

[0080] In some embodiments, the mining equipment for full-height mining in one go includes a front scraper conveyor 9, also known as a full-height mining conveyor 18. The front scraper conveyor 9 is located in front of the working face support. When mining the first coal seam in one-time full-height mining, the front scraper conveyor 9 can be connected to the transfer machine 1 by end-discharge arrangement or cross-side-discharge arrangement.

[0081] For example, the front scraper conveyor 9 can be directly connected to the transfer machine 1 by end unloading. There is no rigid connection between the front scraper conveyor 9 and the transfer machine 1, that is, the front scraper conveyor 9 can move independently of the transfer machine 1. In use, the front scraper conveyor 9 can be pushed forward independently with the help of the jacks of the middle hydraulic support 15 and the transition support 11.

[0082] In other embodiments, the front scraper conveyor 9 may also be connected to the transfer machine 1 in a cross-side unloading arrangement, so that the front scraper conveyor 9 can move forward synchronously with the transfer machine 1.

[0083] In some embodiments, the front scraper conveyor 9 is connected to the transfer conveyor 1 via an end-discharge arrangement, and the rear scraper conveyor 10, after conveying the material behind the working face support through the connecting roadway 13, is connected to the transfer conveyor 1 via a cross-side-discharge arrangement. Therefore, once the rear scraper conveyor 10 is installed, the single-pass full-height conveyor 18, due to its end-discharge arrangement, can be directly converted into the front scraper conveyor 9 for top coal caving without any changes, thus simplifying the overall conversion process.

[0084] The scraper conveyor 10 is then connected to the transfer machine 1 via a cross-side unloading arrangement, which enables the scraper conveyor 10 and the transfer machine 1 to move synchronously, fully meeting the needs of top coal caving production.

[0085] In some embodiments, the front scraper conveyor 9 is connected to the transfer conveyor 1 via a cross-side unloading arrangement, that is, the aforementioned single-pass full-height conveyor 18 is directly connected to the transfer conveyor 1 via a cross-side unloading arrangement. In this case, step S5 further includes the following step:

[0086] S51: The middle trough and tail drive unit of the rear scraper conveyor 10 are transported to the rear of the working face support via the connecting roadway 13. For example, the middle trough and tail drive unit of the rear scraper conveyor 10 can be transported to the rear of the aforementioned middle hydraulic support 15 and transition support 11 via the auxiliary transport roadway 14 and connecting roadway 13 using traction equipment.

[0087] S52: Disconnect the connection between the middle trough and the transition trough of the front scraper conveyor 9, and then move the transition trough and drive unit of the front scraper conveyor 9 backward and connect them with the middle trough of the rear scraper conveyor 10 to construct a complete rear scraper conveyor 10. Thus, since the head drive unit of the front scraper conveyor 9 is arranged in a cross-side discharge configuration, by removing the head drive unit and transition trough of the front scraper conveyor 9 and directly using them as the head drive unit and transition trough of the rear scraper conveyor 10, the installation arrangement of the rear scraper conveyor 10 is facilitated, and the installation requirements of the cross-side discharge arrangement of the rear scraper conveyor 10 are also met.

[0088] Specifically, the connection mechanism between the middle trough and the head transition trough of the front scraper conveyor 9 can be a dumbbell pin. When disassembling, the dumbbell pin can be removed directly, so that the middle trough of the front scraper conveyor 9 can be separated from the head transition trough and the head drive part.

[0089] S53: The end-discharge transition trough and drive unit are transported to the front scraper conveyor 9 via the connecting lane 13 and connected to the middle trough of the front scraper conveyor 9 to construct a new front scraper conveyor 9. Since the transition trough and head drive unit of the front scraper conveyor 9 have been replaced by the rear scraper conveyor 10, the end-discharge transition trough and head drive unit need to be transported to the front scraper conveyor 9 via the auxiliary transport lane 14 and the connecting lane 13 and connected to the remaining middle trough, thus satisfying the installation requirements of the front scraper conveyor 9 with an end-discharge arrangement.

[0090] In some embodiments, step S6 further includes the following step: conveying a portion of the transport trough of the transfer machine 1 to the front side of the tail of the transfer machine 1 via the connecting lane 13 to fill the missing portion between the front scraper conveyor 9 and the rear scraper conveyor 10.

[0091] Specifically, due to the addition of the rear scraper conveyor 10, the original length of the transfer machine 1 could not meet the needs of top coal caving mining. Several transport troughs of the transfer machine 1 could be transported into the transport roadway 12 via the auxiliary transport roadway 14 and the connecting roadway 13. The additional transport troughs were then connected between the tail of the transfer machine 1 and the front of the transfer machine 1, thereby increasing the length of the transfer machine 1 and meeting the needs of top coal caving mining.

[0092] In some embodiments, such as Figure 1 and Figure 2 As shown, during the top coal caving process, the transport roadway 12 serving the working face is equipped with a single-row advanced support 7, a rear advanced support 4, and a front advanced support 3 arranged sequentially along the mining direction. The single-row advanced support 7 is located on the non-production side of the transfer machine 1 and is connected to the rear advanced support 4. Specifically, the non-production side can be the right side of the transfer machine 1, and the single-row advanced support 7 can be arranged only on the right side of the transfer machine 1. The top beam and base of the single-row advanced support 7 can be connected to the top beam and base of the rear advanced support 4 respectively through connecting beams, etc. The single-row advanced support 7 can improve the overall support area, thereby fully meeting the needs of advanced support.

[0093] The above-mentioned top coal caving equipment includes the following steps: transporting the single-row advance support 7 through the connecting roadway 13 to the non-production side of the transport roadway 12 and connecting it to the rear of the rear advance support 4.

[0094] Specifically, the single-row advanced support 7 is transported into the non-production side of the transport lane 12 via the auxiliary transport lane 14 and the connecting lane 13, and is located behind the aforementioned rear advanced support 4. Then, the top beam and base of the single-row advanced support 7 can be rigidly connected to the top beam and base of the right frame of the rear advanced support 4 through the non-extendable connecting beam. At this time, the movement of the single-row advanced support 7 is consistent with that of the front rear advanced support 4, and the single-row advanced support 7 can work together with the lagging end support 8 to protect the top of the machine head triangle area.

[0095] In some embodiments, an auxiliary transport lane 14 is provided beside the transport lane 12, such as... Figures 3 to 5 As shown, the auxiliary transport lane 14 can be located on the side of the transport lane 12 away from the working face. The auxiliary transport lane 14 can extend along the extension direction of the transport lane 12. The auxiliary transport lane 14 is connected to the transport lane 12 through the connecting lane 13. The connecting lane 13 can extend in the left-right direction. The left end of the connecting lane 13 can be connected to the transport lane 12, and the right end of the connecting lane 13 can be connected to the auxiliary transport lane 14. The head drive unit, head transition trough, and single-row advance support 7 of the aforementioned front scraper conveyor 9 can be transported to the working face through the connecting lane 13 and the auxiliary transport lane 14. In some other embodiments, if the aforementioned full-height conveyor 18 itself adopts an end-discharge arrangement, the head drive unit and head transition trough of the rear scraper conveyor can be transported into the working face via the auxiliary transport lane 14 and the connecting lane 13.

[0096] In some embodiments, such as Figures 3 to 5 As shown, the working face is provided with multiple central hydraulic supports 15, which are arranged sequentially along the extension direction of the working face, and each of the central hydraulic supports 15 has a transition support 11 at both ends. Four transition supports 11 may be provided on the left side of the central hydraulic supports 15, and three transition supports 11 may be provided on the right side of the central hydraulic supports 15.

[0097] The central hydraulic support 15 includes a telescopic slide plate and a tail beam. During a full-height mining operation, the telescopic slide plate retracts, and the tail beam lowers to its lowest position. The lowest position is the lowest point where the tail beam can swing downwards. This prevents the collapse of the roof from impacting the rear of the support.

[0098] In some embodiments, the height adjustment range of the central hydraulic support 15 is determined by: using the maximum coal thickness revealed by the borehole diagram of the working face as a reference, and then setting parameters upward on the reference as the maximum height adjustment of the central hydraulic support 15, and determining the minimum height adjustment of the central hydraulic support 15 based on the well drilling method and the actual situation of existing equipment.

[0099] Specifically, the central hydraulic support 15 can adopt the basic configuration of a two-column shield-type top coal caving support, which has the function of top coal caving and is also equipped with a swing tail beam and a telescopic insert plate. The height adjustment range of the central hydraulic support 15 can be determined by the coal thickness distribution range of the first half (first coal seam). When determining the height, extreme outliers can be eliminated. The maximum coal thickness revealed by the borehole map in the mining direction of the working face is used as the benchmark, and then a certain parameter is added upwards as the maximum height adjustment of the hydraulic support.

[0100] The difference between the maximum and minimum height of the support frame constitutes its height adjustment range. A larger height adjustment range allows for a wider range of applications, but an excessively large range can complicate support frame structural design and reduce reliability. Therefore, when determining the minimum height adjustment, the minimum support height can be determined based on the well site development method, the current equipment technology level, the maximum allowable size of the downhole, and the height adjustment range permitted by the current equipment technology level.

[0101] In some embodiments, the power of the coal mining machine 16 applied in the above mining method can be determined by the instantaneous coal drop volume corresponding to the maximum cutting height, and the drum diameter can be determined by the cutting range, which should be 0.55 to 0.6 of the maximum cutting height.

[0102] The following describes a specific example of the mining method according to an embodiment of the present invention.

[0103] The mining method of this invention mainly includes three stages: full-height mining in one pass, conversion from full-height mining to top coal caving, and top coal caving in one pass.

[0104] (1) Full-height stage process of one-time mining in fully mechanized mining: The equipment is installed in the working face cut. The front scraper conveyor 9 is arranged in the front of the working face support by end unloading or cross side unloading. The coal mining machine 16 straddles the front scraper conveyor 9. The working face support adopts the fully mechanized top coal caving frame type. The rear insert plate is in the retracted state and the tail beam is lowered to the lowest position to avoid the impact of the collapsed roof on the rear of the hydraulic support.

[0105] (2) Fully mechanized mining one-time full height to fully mechanized top coal caving conversion process: When the coal seam thickness reaches the critical value of process conversion, ① when the working face advances to a set distance behind the connecting roadway 13 (the set distance should be able to meet the space requirements of equipment layout), disconnect the connection between the end support 8 and the tail push beam of the transfer machine 1, and the end support 8 will no longer advance with the working face at this time.

[0106] ② The working face continues to advance. After each step, temporary support measures (point pillars, timber stacks, single hydraulic props, etc.) are used to temporarily support the roof in front of the end support 8. Support is provided as the working face moves until the working face stops advancing after reaching the set distance. At this time, the head of the working face is directly facing the connecting roadway 13, and all hydraulic supports of the working face and the advanced section are in the supported state.

[0107] ③The tail drive unit and middle trough of the rear scraper conveyor 10 are transported by the traction equipment to the rear of the working face through the auxiliary transport roadway 14 and the connecting roadway 13, and connected to the rear of the base of the middle support and the transition support 11. The connection method is generally to use chains, jacks, etc. The tail of the transfer machine 1 is moved back along with the tail push beam and connected to the end support 8.

[0108] ④ If the front scraper conveyor 9 adopts the end-discharge arrangement: the transition trough of the rear scraper conveyor 10 and the head drive unit are transported to the back of the working face support through the auxiliary transport roadway 14 and the connecting roadway 13, and connected to the middle trough of the rear scraper conveyor 10. At this time, the rear scraper conveyor 10 is in the cross-side discharge arrangement.

[0109] If the front scraper conveyor 9 adopts a cross-side unloading arrangement: disconnect the connection between the middle trough and the transition trough of the front scraper conveyor 9, disconnect the connection between the transfer machine 1 and the head drive unit of the front scraper conveyor 9, move the transition trough and the head drive unit of the front scraper conveyor 9 backward, and connect them with the rear scraper conveyor 10. The rear scraper conveyor 10 is then arranged in a cross-side unloading manner. The transition trough and the head drive unit of the front scraper conveyor 9 are transported to the front of the working face support through the auxiliary transport roadway 14 and the connecting roadway 13, and connected to the middle trough of the front scraper conveyor 9. The front scraper conveyor 9 is then arranged in an end-unloading manner.

[0110] ⑤ Transport several sections of the transfer machine 1 through the auxiliary transport lane 14 and the connecting lane 13 into the transport lane 12, and fill the gap of the transfer machine 1 section between the head drive of the front scraper conveyor 9 and the rear scraper conveyor 10.

[0111] ⑥ The single-row advance support 7 (two-link advance support) is transported via auxiliary haulage roadway 14 and connecting roadway 13 to the rear of the non-production side advance support 4 in haulage roadway 12. The top beam and base of the two-link advance support are rigidly connected to the top beam and base of the right frame of the rear advance support 4 via non-extendable connecting beams. At this point, the movement of the two-link advance support is synchronized with that of the rear advance support 4, and it can work in conjunction with the lagging end support 8 to provide roof protection for the triangular area of ​​the machine head. This completes the conversion from fully mechanized single-pass full-height mining to fully mechanized top coal caving mining.

[0112] (3) Longwall top coal caving stage process: At this time, the front scraper conveyor 9 adopts an end-discharge arrangement, and the rear scraper conveyor 10 adopts a cross-side-discharge arrangement. On the side of the transport roadway, the head drive of the rear scraper conveyor 10 is arranged vertically to increase the pedestrian space behind the front scraper conveyor 9. After mining back to the stop line, the coal mining operation of the entire working face is completed.

[0113] The beneficial effects of the coal seam mining method with varying coal seam thickness according to embodiments of the present invention are as follows:

[0114] 1) A novel mining technology is provided for coal mining faces where the coal seam thickness varies unidirectionally in the mining direction and the coefficient of variation of the coal seam is large (the maximum coal thickness is about twice the minimum coal thickness).

[0115] 2) This process optimizes the design of supporting technologies and equipment for the working face. By using a single set of equipment during the working face mining process, it integrates two types of processes: one-time full-height mining and top coal caving mining, thus achieving lean production of coal resources.

[0116] 3) The head drive section and transition trough of the front scraper conveyor can be used to connect the transfer machine and the middle trough of the rear scraper conveyor, ensuring the efficiency of process conversion and reducing the difficulty of managing spare parts.

[0117] 4) Compared with the full-height mining process in one go: The mining height range of the support used in this invention is relatively low, thus avoiding the problems of roof collapse and roof fall when the machine mining height is too high, as well as the breakage of the ear plate of the shield beam balance jack when the support is kept in a low posture for a long time.

[0118] 5) Compared with segmented relocation mining: reduced equipment investment, reduced underground work, and avoidance of a large amount of stagnant coal resources.

[0119] 6) Compared with the whole-process top coal caving process: it has higher propulsion efficiency, higher comprehensive resource recovery rate, and lower coal gangue content.

[0120] In summary, this invention is a lean mining process applicable to specific coal occurrence conditions. It promotes the reduction of equipment investment, the reduction of workers' workload, the improvement of resource recovery rate, the improvement of coal quality, and the enhancement of mine safety and efficiency, and has the prospect of widespread promotion.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A method for mining coal seams with varying thickness, characterized in that, The thickened coal seam includes a first coal seam and a second coal seam arranged sequentially in the mining direction, wherein the first coal seam is thinner than the second coal seam, and the mining method includes the following steps: S1: A connecting roadway is pre-excavated in the critical area between the first coal seam and the second coal seam; S2: The first coal seam is mined by extracting the full height in one go; S3: When the working face advances to a set distance from the connecting roadway, disconnect the end support and the transfer machine; S4: Continue to advance the working face and provide support for the area between the end support and the transfer machine; S5: When the working face is advanced to the position opposite the connecting roadway, the rear scraper conveyor is transported to the rear of the working face support through the connecting roadway and arranged. S6: Move the tail of the transfer machine backward and connect it to the end support to construct a top coal caving device; S7: The second coal seam is mined by top coal caving; The mining equipment for full-height mining in one operation includes a front scraper conveyor, which is located in front of the working face support and is connected to the transfer machine by an end-discharge arrangement or a cross-side-discharge arrangement. The working face is provided with multiple central hydraulic supports, which are arranged sequentially along the extension direction of the working face, and each of the multiple central hydraulic supports is provided with a transition support at both ends. The central hydraulic support includes a telescopic insert plate and a tail beam. During the process of mining a full height in one go, the telescopic insert plate retracts and the tail beam is lowered to its lowest position. The height adjustment range of the central hydraulic support is determined in the following way: Using the maximum coal thickness revealed by the borehole diagram of the working face as a reference, a parameter is then set upwards on the reference as the maximum height adjustment of the central hydraulic support; The minimum height adjustment of the central hydraulic support is determined based on the well drilling method and the actual situation of the existing equipment; Step S5 also includes the following steps: S51: The middle trough and tail drive unit of the rear scraper conveyor are transported to the rear of the working face support via the connecting tunnel; S52: Disconnect the connection between the middle trough and the transition trough of the front scraper conveyor, and then move the transition trough and the drive unit of the front scraper conveyor backward and connect them with the middle trough of the rear scraper conveyor to construct the complete rear scraper conveyor. S53: The end-discharge transition trough and drive unit are transported via the connecting tunnel to the front scraper conveyor and connected to the middle trough of the front scraper conveyor to construct a new front scraper conveyor.

2. The method for mining coal seams with varying thickness according to claim 1, characterized in that, In step S4, the area between the end support and the transfer machine is supported by temporary support. The temporary support includes at least one of the following: point pillars, timber stacks, and single hydraulic props.

3. The method for mining coal seams with varying thickness according to claim 1, characterized in that, In step S5, the working face support includes a central hydraulic support and a transition support, and the rear scraper conveyor is connected to the rear of the central hydraulic support and the transition support.

4. The method for mining coal seams with varying thickness according to claim 1, characterized in that, The front scraper conveyor is connected to the transfer machine via an end-discharge arrangement. The rear scraper conveyor is transported to the rear of the working face support via the connecting roadway, and then connected to the transfer machine via a cross-side-discharge arrangement.

5. The method for mining coal seams with varying thickness according to claim 1, characterized in that, Step S6 also includes the following steps: The transport trough of a portion of the transfer machine is conveyed via the connecting tunnel to the front side of the tail of the transfer machine to fill the missing part between the front scraper conveyor and the rear scraper conveyor.

6. The method for mining coal seams with varying thickness according to claim 1, characterized in that, During the top coal caving process, a single-row advanced support, a rear advanced support, and a front advanced support are arranged sequentially along the mining direction in the transport roadway serving the working face. The single-row advanced support is located on the non-production side of the transfer machine and is connected to the rear advanced support. The construction of the top coal caving equipment includes the following steps: The single-row advanced support is transported via the connecting lane to the non-production side of the transport lane and connected to the rear of the rear advanced support.

7. The method for mining coal seams with varying thickness according to claim 6, characterized in that, An auxiliary transport lane is provided on the side of the transport lane. The auxiliary transport lane is connected to the transport lane through a connecting lane. The single-row advanced support and the rear scraper conveyor are transported through the auxiliary transport lane and the connecting lane.

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