Variable coal pillar mining method

Abstract

The present invention provides a coal pillar mining method, which relates to the field of coal mining technology and aims to address the problem of low coal recovery rate. This method involves: during excavation of a first tunnel, after deviating away from the goaf, excavation continues in a direction parallel to the length of a predetermined coal pillar, forming a protruding coal pillar. After the protruding coal pillar is formed, a second tunnel is excavated from the base of the protruding coal pillar in a direction parallel to the predetermined coal pillar, with both ends connected to the first tunnel. This method can improve coal recovery rate.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mining, in particular to a coal pillar-changing mining method. Background Art

[0002] At present, underground coal mining usually adopts a longwall mining mode in which two tunnels 34 enclose a working face 31, and a section coal pillar 33 is left between adjacent working faces 31. Figure 1 and Figure 2 Typically, the size of the adjacent coal pillars 33 of a working face 31 will not change once it is determined. The adjacent coal pillars 33 usually have two sizes, namely, large coal pillars of 20m-50m and small coal pillars of 4m-10m.

[0003] However, in some cases, such coal pillars are difficult to meet on-site requirements: while large coal pillars provide effective support and can isolate harmful gases or mine water from adjacent goafs 32, they waste coal resources and result in a low recovery rate. Small coal pillars offer high recovery rates and coal extraction rates, but often exhibit deformation in the roadways 34 and coal pillars, which can easily lead to leakage of harmful gases and mine water from adjacent goafs 32, compromising the safety of the working face 31 and adjacent goafs 32. During small coal pillar mining, if this occurs, reinforcement measures such as coal wall grouting and spraying are necessary. While these measures can address on-site issues to a certain extent, they can still affect excavation progress or pose significant safety risks. For example, oxygen leakage into the goaf 32 can lead to natural gas explosions in the goaf 32, gas leakage into the roadway 34 can lead to gas explosions, and water leakage from the goaf 32 into the roadway 34 can lead to water accumulation in the roadway 34. Summary of the Invention

[0004] The first aspect of the present invention aims to provide a coal pillar mining method to solve the technical problem of low coal recovery rate in the prior art.

[0005] The variable coal pillar mining method provided in the first aspect of the present invention includes: when excavating a first tunnel, after deviating in the direction away from the goaf, then continuing to excavate along the length direction parallel to the preset coal pillar to form a protruding coal pillar; after the protruding coal pillar is formed, a second tunnel with both ends connected to the first tunnel is excavated from the root of the protruding coal pillar along a direction parallel to the preset coal pillar.

[0006] The beneficial effects of the coal pillar mining method of the present invention are:

[0007] During the excavation of the first tunnel, drainage and ventilation equipment are often inadequate, resulting in weak exhaust and drainage capabilities. Therefore, if excavation strictly follows the edge of the pre-designed coal pillar and a leak occurs, the drainage and ventilation capacity will be far behind the rate of gas leakage or water intrusion, which can easily lead to danger. Therefore, when designing the first tunnel, or if the pre-designed tunnel is found to not meet requirements during excavation, the excavation direction of the first tunnel can be adjusted to increase the thickness of the coal pillar between the first tunnel and the goaf, forming a protruding coal pillar. This increased coal pillar thickness not only effectively isolates gas and water from the goaf, preventing them from leaking into the first tunnel, but also reduces the risk of oxygen leaking from the first tunnel into the goaf, which could cause spontaneous combustion. Furthermore, because the first tunnel is partially deflected away from the goaf, this deflection method can improve coal recovery compared to directly using a large coal pillar, thus promoting green mining.

[0008] In an optional technical solution, after continuing to excavate in a direction parallel to the length of the preset coal pillar, the first tunnel is also excavated obliquely in a direction toward the goaf.

[0009] In an optional technical solution, after the first tunnel is excavated obliquely in the direction toward the goaf, the first tunnel is further excavated in a length direction parallel to the preset coal pillar.

[0010] Among the optional technical solutions, the variable coal pillar mining method also includes:

[0011] In an optional technical solution, after excavating the second tunnel, the part of the first tunnel corresponding to the protruding coal pillar is filled.

[0012] In an optional technical solution, when excavating the second tunnel, forward excavation, reverse excavation or multi-head excavation is adopted.

[0013] In an optional technical solution, the multi-head excavation also continues to excavate the first tunnel.

[0014] In an optional technical solution, during the multi-head excavation, a connecting tunnel is excavated at the lowest point of the protruding coal pillar, and then excavated upward to both sides in a direction parallel to the preset coal pillar.

[0015] In an optional technical solution, the deflection is in the direction away from the goaf, and the deflection angle is 10°~15°.

[0016] In an optional technical solution, the direction toward the goaf is tilted, and the tilt angle is 10°~15°.

[0017] In an optional technical solution, the maximum width of the protruding coal pillar is 20m~50m. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the background technology, the following briefly introduces the drawings required for use in the embodiments or the background technology description. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0019] Figure 1 It is a schematic top view of the mining method in the background technology.

[0020] Figure 2 It is a side view of the mining method in the background technology.

[0021] Figure 3 A schematic diagram of a tunnel to be excavated in the variable coal pillar mining method provided in an embodiment of the present invention.

[0022] Figure 4 A schematic diagram of a tunnel to be excavated in the variable coal pillar mining method provided in an embodiment of the present invention showing an area where the coal pillar width needs to be changed.

[0023] Figure 5 This is a schematic diagram of setting a region for changing the width of a coal pillar in the variable coal pillar mining method provided in an embodiment of the present invention.

[0024] Figure 6 A schematic diagram of the second tunnel excavated in the variable coal pillar mining method provided in an embodiment of the present invention.

[0025] Figure 7 A schematic diagram of back-excavating a second tunnel in the variable coal pillar mining method provided in an embodiment of the present invention.

[0026] Figure 8 A schematic diagram of multi-head excavation of the second tunnel in the variable coal pillar mining method provided in an embodiment of the present invention.

[0027] Figure 9 This is a schematic diagram of the multi-head excavation of the second tunnel while continuing to excavate the first tunnel in the variable coal pillar mining method provided by an embodiment of the present invention.

[0028] Figure 10 A schematic diagram of setting a protruding coal pillar in a specific implementation of the variable coal pillar mining method provided in an embodiment of the present invention.

[0029] Figure 11 A side view of a second tunnel being excavated by multiple heads in a specific implementation of the variable coal pillar mining method provided in an embodiment of the present invention.

[0030] Description of reference numerals:

[0031] 11-first lane; 12-second lane; 13-filling area;

[0032] 21-preset coal pillar; 22-protruding coal pillar; 23-connecting tunnel;

[0033] 31-working face; 32-goaf; 33-section coal pillar; 34-tunnel. DETAILED DESCRIPTION

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0035] Example 1:

[0036] Figure 3 A schematic diagram of a tunnel to be excavated in the variable coal pillar mining method provided in an embodiment of the present invention. Figure 4 A schematic diagram of a tunnel to be excavated in the variable coal pillar mining method provided in an embodiment of the present invention showing an area where the coal pillar width needs to be changed. Figure 5 This is a schematic diagram of setting a region for changing the width of a coal pillar in the variable coal pillar mining method provided in an embodiment of the present invention. Figure 6 A schematic diagram of the second tunnel excavated in the variable coal pillar mining method provided in an embodiment of the present invention. Figure 7 A schematic diagram of back-excavating a second tunnel in the variable coal pillar mining method provided in an embodiment of the present invention. Figure 8 Schematic diagram of multi-head excavation of the second tunnel in the variable coal pillar mining method provided by the embodiment of the present invention, wherein Figure 8 The state shown in the figure is the state after the connecting tunnel is filled. Figure 3-Figure 8 As shown, the variable coal pillar mining method provided in the first embodiment of the present invention includes: when excavating the first tunnel 11, after deviating in the direction away from the goaf 32, then continuing to excavate along the length direction parallel to the preset coal pillar 21 to form a protruding coal pillar 22; after the protruding coal pillar 22 is formed, excavating a second tunnel 12 from the root of the protruding coal pillar 22 along the direction parallel to the preset coal pillar 21, with both ends connected to the first tunnel 11.

[0037] Because drainage and ventilation equipment are often inadequate during excavation of the first roadway 11, resulting in weak exhaust and drainage capabilities, if excavation is conducted solely along the edge of the pre-set coal pillar 21 and a leak occurs, the drainage and ventilation capabilities will be far less capable than the gas leak or water intrusion into the roadway 34, potentially leading to a dangerous situation. Therefore, when designing the first roadway 11, or if the pre-set roadway is found to be insufficient during excavation, the excavation direction of the first roadway 11 can be adjusted to increase the thickness of the coal pillar between the first roadway 11 and the goaf 32, forming a protruding coal pillar 22. This increased thickness not only effectively isolates gas and water from the goaf 32, preventing them from leaking into the first roadway 11, but also reduces the risk of oxygen from the first roadway 11 leaking into the goaf 32, potentially causing spontaneous combustion in the goaf 32. Furthermore, because the first roadway 11 is partially deflected away from the goaf 32, the deflection method can improve the coal recovery rate compared to directly using a large coal pillar, facilitating green mining. By excavating a second roadway 12 within the protruding coal pillar 22 to connect with the first roadway 11, the second roadway 12 within the protruding coal pillar 22 and the first roadway 11 outside the protruding coal pillar 22 can be combined to form a single integrated roadway, facilitating the deployment of mining equipment along the working face 31 for mining. Furthermore, the coal within the protruding coal pillar 22 can be mined, thereby increasing the recovery rate.

[0038] Because drainage and exhaust facilities were incomplete when the protruding coal pillar 22 was excavated, drainage and exhaust capabilities were weak, making it difficult to respond to gas leaks or water seepage accidents. However, after the protruding coal pillar 22 was formed, the equipment in the first tunnel 11 was fully installed, providing strong drainage and ventilation capabilities. Therefore, excavating the protruding coal pillar 22 at this time could dilute the leaked gas or drain the leaked water in a timely manner, eliminating any danger, and thus allowing excavation of the second tunnel 12 to proceed.

[0039] Specifically, whether the preset overall roadway meets the requirements depends on the geological data obtained before designing the first roadway 11. If the geological data shows that the coal seam gas content is high or there is water accumulation in the goaf, such as Figure 3 As shown, a protruding coal pillar 22 can be designed in the first tunnel 11 during design, as shown in FIG. Figure 4 and Figure 5 As shown, when the tunnel reaches the corresponding position, it deviates in the direction away from the goaf 32. Alternatively, when geological data is insufficient, tunneling can be carried out according to the preset coal pillar 21. During the tunneling process, when it is found that the gas exceeds the standard or the water inflow is too large, the first tunnel 11 can be deviated and tunneled. The specific situation of gas exceeding the standard can be that the gas concentration exceeds 1% or the carbon dioxide concentration exceeds 1.5%. And the water inflow is too large, for example, due to water accumulation or water inflow at the tunneling head, the tunneling speed is reduced by more than 30%. Figure 4 and Figure 5 The area enclosed by the dotted rectangle on the left side of the center is the area with high gas content or high water content shown by geological data.

[0040] In this application, "excavation parallel to the length of the predetermined coal pillar 21" does not necessarily require that the angle between the excavation direction and the length of the predetermined coal pillar 21 be exact, nor does it necessarily mean that an angle of even 0.01° is prohibited. In this application, "parallel to the length of the predetermined coal pillar 21" encompasses situations where the angle between the excavation direction and the length of the predetermined coal pillar 21 is less than 5°.

[0041] like Figure 5 As shown, optionally, it is tilted away from the goaf 32, and the tilt angle is 10° to 15°.

[0042] By tilting the tunnel away from the goaf 32 at the aforementioned angle, the width of the coal pillar can be increased to the desired width within an appropriate overall tunnel length range. Furthermore, by employing a deflection angle within the aforementioned range, the speed of angle conversion in the first tunnel 11 can be controlled appropriately, thereby reducing the difficulty of changing the tunneling angle.

[0043] like Figure 5 As shown, optionally, it is tilted toward the goaf 32, and the tilt angle is 10° to 15°.

[0044] By tilting the tunnel toward the goaf 32 at the aforementioned angle, the width of the coal pillar can be reduced to the desired width within an appropriate range of the overall tunnel length. Furthermore, by employing a deflection angle within the aforementioned range, the speed of the angle conversion of the first tunnel 11 can be controlled appropriately, thereby reducing the difficulty of changing the tunneling angle.

[0045] like Figure 5 As shown, optionally, after continuing to excavate in a length direction parallel to the preset coal pillar 21 , the first tunnel 11 is also excavated obliquely in a direction toward the goaf 32 .

[0046] By deviating in the direction toward the goaf 32, the excavation position can be restored to the preset coal pillar 21 after bypassing the higher-risk position in the preset coal pillar 21, thereby reducing the width of the coal pillar in the local area, thereby reducing coal pillar waste and improving the coal recovery rate.

[0047] Of course, in another implementation, if the area where the coal pillar needs to be thickened is the end of the first tunnel 11 , it is not necessary to excavate the first tunnel 11 obliquely toward the goaf 32 .

[0048] Optionally, the maximum width of the protruding coal pillar 22 is 20m-50m.

[0049] When the width of the protruding coal pillar 22 is selected to be the above value, it can be equivalent to the width of the large coal pillar, which is sufficient to effectively support the coal seam above, and form a sufficient barrier between the goaf 32 and the first tunnel 11 to prevent water seepage in the goaf 32, gas leakage, or oxygen in the first tunnel 11 from entering the goaf 32 and causing danger.

[0050] like Figure 5 As shown, optionally, after the first tunnel 11 is excavated obliquely in the direction toward the goaf 32 , the first tunnel 11 is further excavated in a length direction parallel to the preset coal pillar 21 .

[0051] After excavating the protruding coal pillar 22 and excavating obliquely toward the goaf 32, the first tunnel 11 is continued to be excavated in the direction parallel to the preset coal pillar 21. This not only reduces the waste of coal seams, but also can be coaxially arranged with the first tunnel 11 before excavating the protruding coal pillar 22. If the protruding coal pillar 22 is excavated through, they can form an integral tunnel together.

[0052] Of course, in another implementation method, if the area where the coal pillar needs to be thickened is close to the first tunnel 11, and the process of excavating the first tunnel 11 obliquely toward the goaf 32 is completed and the width of the preset coal pillar 21 is reached at the same time, the end of the first tunnel 11 is also reached, then there is no need to excavate the first tunnel 11 in a direction parallel to the preset coal pillar 21.

[0053] like Figure 6-Figure 8 As shown, optionally, after the second tunnel 12 is excavated, a portion of the first tunnel 11 corresponding to the protruding coal pillar 22 is filled.

[0054] After excavating the second roadway 12, the second roadway 12 within the protruding coal pillar 22 and the first roadway 11 outside the protruding coal pillar 22 together form a single, integrated roadway. When ventilating this integrated roadway, because the portion of the first roadway 11 corresponding to the protruding coal pillar 22 is zigzag-shaped, the ventilation airflow primarily passes through the second roadway 12 rather than the portion of the first roadway 11 outside the protruding coal pillar 22. Consequently, the gas concentration in this portion of the first roadway 11 may increase. Therefore, after the ventilation capacity of the integrated roadway is established, even if the portion of the first roadway 11 corresponding to the protruding coal pillar 22 is filled to form the filling area 13, the dangerously high gas concentration in this portion can be prevented. Because the space in this portion is occupied by the filling material, even if there is a gas leak in the coal seam near this portion, the leaked gas will remain in the integrated roadway and be carried away by the ventilation of the integrated roadway.

[0055] like Figure 6-Figure 8 As shown, optionally, when excavating the second tunnel 12, forward excavation, reverse excavation or multi-head excavation is adopted.

[0056] By adopting multiple methods to excavate the second roadway 12, it is possible to adapt to the specific conditions of the protruding coal pillar 22. Specifically, if the rear end of the protruding coal pillar 22 is high, the method of excavating the second roadway 12 in a forward direction can be adopted. This is because when excavating the second roadway 12, it is possible to use an upward excavation method, and water in the coal body flows toward the head of the first roadway 11, without interfering with the excavation working face 31. If the head end of the protruding coal pillar 22 is high, the method of excavating the second roadway 12 in a reverse direction can be adopted. This allows water in the coal body to flow toward the tail of the first roadway 11, without interfering with the excavation working face 31. Furthermore, by adopting a multi-head excavation method, a connecting roadway 23 can be excavated from the approximate middle of the protruding coal pillar 22 toward the goaf 32, and excavation can be carried out from the inner end of the connecting roadway 23 toward the head and tail of the first roadway 11, respectively. This can increase the excavation speed of the second roadway 12 and facilitate the earlier formation of the working face 31.

[0057] Figure 9 This is a schematic diagram of the method for mining coal with variable pillars provided in an embodiment of the present invention, wherein multiple tunnels are excavated into the second tunnel while continuing to excavate the first tunnel. Figure 9 The state shown in the figure is the state after the connecting tunnel is filled. Figure 9 As shown, optionally, the first tunnel 11 is continued to be excavated during multi-head excavation.

[0058] When excavating the second tunnel 12, it is not necessary to complete the excavation of the first tunnel 11. In particular, when the protruding coal pillar 22 is far away from the tail of the first tunnel 11, the excavation of the first tunnel 11 to its tail and the multi-head excavation of the second tunnel 12 can be carried out simultaneously to increase the formation speed of the working face 31.

[0059] Figure 11 A side view of a second tunnel being driven by multiple heads in a specific implementation of the variable coal pillar mining method provided by an embodiment of the present invention. Figure 11 As shown, optionally, during multi-head excavation, a connecting tunnel 23 is excavated at the lowest point of the protruding coal pillar 22, and then excavated upward to both sides in a direction parallel to the preset coal pillar 21.

[0060] The connecting tunnel 23 is set at the lowest point of the protruding coal pillar 22. After the excavation of the connecting tunnel 23 is completed, the tunnel is excavated from the inner end of the connecting tunnel 23 to both sides. No matter which side is excavated, the end of the connecting tunnel 23 is the lowest position of the entire tunnel being excavated. That is, no matter which side is excavated, it is excavated upward. If there is a protruding coal pillar 22, Figure 11 In the waterlogged area shown in the middle blue area, water during excavation flows to the end of the connecting tunnel 23. Because drainage facilities have already been laid in the first tunnel 11 outside the protruding coal pillar 22 during excavation of the connecting tunnel 23, water flowing into the connecting tunnel 23 can be quickly pumped away. Furthermore, during excavation of the second tunnel 12, water accumulation at the excavation face 31 will not interfere with excavation work.

[0061] The following embodiments are listed to specifically illustrate this method:

[0062] like Figure 3 As shown, first, for a certain working face 31 , the first tunnel 11 adjacent to the goaf 32 is excavated according to a small coal pillar of 8 m. Figure 10 A schematic diagram of a protruding coal pillar in a specific implementation of the variable coal pillar mining method provided by an embodiment of the present invention. Figure 10 and Figure 11 As shown, when excavating to a certain position, water was found to be gushing into the first tunnel 11 from one side of the goaf 32. At this time, the entire tunnel was excavated downward, and head-on excavation was prone to water accumulation, making drainage difficult and seriously affecting the excavation speed. The excavation direction was deviated by 10° to 15° away from the goaf 32. When the width of the protruding coal pillar 22 reached 30m, the deviated excavation was stopped and the excavation was changed to a direction parallel to the length of the preset coal pillar 21. After the water leakage was eliminated, the excavation was deviated by another 10° to 15° toward the goaf 32. When the width of the preset coal pillar 21 was reached, the excavation was changed to a direction parallel to the length of the preset coal pillar 21.

[0063] After excavation is completed and the working face 31 is connected, mining begins. The second tunnel 12 is then excavated in the area of ​​the protruding coal pillar 22. Using the second tunnel 12 for mining can improve the coal recovery rate of the working face 31. Specifically, a connecting tunnel 23 is first excavated from the lowest point of the waterlogged area of ​​the protruding coal pillar 22. After the connecting tunnel 23 is excavated, it is excavated upward from the inner end of the connecting tunnel 23, i.e., the lowest point, to both sides. This not only increases the excavation speed, but also reduces the risk of water accumulation during upward excavation. The gushing water will flow to the inner end of the connecting tunnel 23 and be drained away by the drainage equipment already installed in the first tunnel 11, facilitating excavation.

[0064] After the excavation of the second roadway 12 is completed, the first roadway 11 outside the protruding coal pillar 22 is filled to prevent air leakage and fire. The second roadway 12 within the protruding coal pillar 22 and the first roadway 11 excluding the protruding coal pillar 22 form an integrated roadway. One sidewall of the integrated roadway is the sidewall of the preset coal pillar 21, and the leading sidewall of the integrated roadway can serve as the mining working face 31. Mining through this integrated roadway can improve the recovery rate. Moreover, compared to large coal pillars, the smaller width of the preset coal pillar 21 in this embodiment is more convenient for maintenance, and the stress within it is also lower, making it less prone to the risks caused by sudden stress release.

[0065] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

[0066] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprises" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article, or device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, article, or device that includes the element.

[0067] In the above embodiments, the descriptions of directions such as “upper” and “lower” are all based on the drawings.

[0068] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0069] Thus, the present invention will not be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A coal pillar mining method, characterized in that: include: When excavating the first tunnel (11), the tunnel deviates in the direction away from the goaf (32), and then continues to excavate in the length direction parallel to the preset coal pillar (21) to form a protruding coal pillar (22); after the protruding coal pillar (22) is formed, a second tunnel (12) is excavated from the root of the protruding coal pillar (22) in a direction parallel to the preset coal pillar (21), and the second tunnel (12) is connected to the first tunnel (11) at both ends; when excavating the second tunnel (12), forward excavation, reverse excavation or multi-head excavation is adopted; when the multi-head excavation is used, a connecting tunnel (23) is excavated at the lowest point of the protruding coal pillar (22), and then excavated in the direction parallel to the preset coal pillar (21) to both sides.

2. The coal pillar mining method according to claim 1, characterized in that: After continuing to excavate in a length direction parallel to the preset coal pillar (21), the first tunnel (11) is also excavated obliquely in a direction toward the goaf (32).

3. The coal pillar mining method according to claim 2, characterized in that: After the first tunnel (11) is excavated obliquely in a direction toward the goaf (32), the first tunnel (11) is further excavated in a length direction parallel to the preset coal pillar (21).

4. The coal pillar mining method according to claim 1, characterized in that: After the second tunnel (12) is excavated, the first tunnel (11) is filled with a portion corresponding to the protruding coal pillar (22).

5. The coal pillar mining method according to claim 1, characterized in that: During the multi-head excavation, the first tunnel (11) is also continued to be excavated.

6. The coal pillar mining method according to any one of claims 1 to 5, characterized in that: The deflection is in the direction away from the goaf (32), and the deflection angle is 10° to 15°.

7. The coal pillar mining method according to claim 2, characterized in that: The direction of the deflection is toward the goaf (32), and the deflection angle is 10° to 15°.

8. The coal pillar mining method according to any one of claims 1 to 5, characterized in that: The maximum width of the protruding coal pillar (22) is 20m to 50m.

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