A method of mining thick coal seam open-pit mine based on time-dependent slope

Abstract

The present invention discloses a method for mining against the wall of an open-pit mine in a thick coal seam based on a time-dependent slope, comprising four steps of pressure-releasing mining, wall-expanding mining, wall-mining and wall-pressure drainage. The present invention divides the process of wall-mining into stages, and timely implements wall-pressure drainage, which greatly shortens the existence time of the steep wall slope after wall-mining, and can both mine coal against the wall and maintain the stability of the wall slope. The step grouping and staggered mining scheme realizes the staged and step-by-step implementation of wall-mining, and avoids the concentrated impact on the end wall stability caused by the previous wall-mining method. The pressure-releasing mining realizes the early mining of the upper coal seam during the wall-mining process, avoids the excessively high requirements on the mining equipment capacity of the mine due to concentrated mining, and releases the pressure on the steps of the lower coal seam, thereby increasing the stability of the lower steps. The wall-expanding mining process realizes the wall-mining of the local steps, and simultaneously prepares resources and space in advance for the final wall-mining.

Description

Technical Field

[0001] The invention relates to an open-pit mine sidewall mining method, in particular to an open-pit mine sidewall mining method for a huge thick coal seam based on a time-dependent slope. Background Art

[0002] The mining rate of coal pressure at the end of open-pit mines has always been an important factor affecting the overall mining rate of open-pit mines, especially for thick coal seam open-pit mines in Inner Mongolia Autonomous Region, Xinjiang Uygur Autonomous Region and other places. The thickness of the coal seam exceeds 100m and there are more than 6 coal steps. Due to the large mining depth, many steps and huge amount of coal pressure at the end, the open-pit mine cannot set the slope angle of the end too large due to the requirements of end stability. The resulting loss of coal pressure at the end exceeds one million tons, which not only affects the production efficiency of mining enterprises, but also brings huge challenges to the efficient mining and utilization of coal resources. Based on this, some scholars have proposed the traditional sidewall mining method, but because the multi-step synchronous sidewall method adopted by it has a large disturbance to the end wall, and the steep end wall exists for a long time during the sidewall process, it has a great impact on the stability of the end wall. In recent years, experts and scholars in the field of open-pit mining have proposed the time-effect slope theory through research, that is, time is regarded as one of the factors affecting the stability of the open-pit mine slope. The study found that the increase in the slope angle in a short period of time has limited effect on the overall stability of the slope, which provides theoretical support for sidewall mining under time-effect slope. Based on this, the present invention proposes a method for mining thick coal seam open-pit mines against the wall under the condition of time-dependent slope, so as to solve the problems encountered in current open-pit mining. Summary of the invention

[0003] In view of the problems existing in the above-mentioned prior art, the present invention provides a method for mining thick coal seam open-pit mines based on time-effective slopes, which improves the mining rate of end-wall compressed coal while ensuring the stability of the slope.

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a method for mining against the wall of a thick coal seam open-pit mine based on a time-effect slope, comprising four steps of pressure-releasing mining, wall-expanding mining, wall-implanting mining and wall-pressure dumping; the top two layers of original end wall steps of the coal seam steps are divided into a pressure-releasing step group, the bottom two layers of original end wall steps of the coal seam steps are divided into a wall-implanting step group, and the coal seam steps between the pressure-releasing step group and the wall-implanting step group are divided into a plurality of wall-expanding step groups according to 2-3 layers of original end wall steps as a group;

[0005] Pressure relief mining: starting from one side of the spoil dump in the open-pit mine, along the advancing direction of the open-pit mine, the coal of the original end wall step of the lower layer of the pressure relief step group is mined, and the original end wall step of the upper layer of the pressure relief step group is mined to keep the original state; as the open-pit mine working face 18 continues to advance, the pressure relief mining is also continuously carried out, and finally the two layers of the original end wall step of the pressure relief step group are merged into one layer;

[0006] Wall expansion mining: When the length of pressure relief mining exceeds 50m, starting from one side of the spoil dump in the open-pit mine, along the direction of the open-pit mine, the coal of all the original end wall steps in the top wall expansion step group is mined; after the top wall expansion step group is advanced for more than 50m, the second wall expansion step group below it starts to be mined according to the steps of the top wall expansion step group, and similarly, mining is carried out in sequence until the bottom wall expansion step group;

[0007] Sidewall mining: When the mining length of the lowest sidewall step group exceeds 50m, the coal of the original sidewall step on the upper layer of the sidewall step group will be mined starting from the side of the dump in the open-pit mine and along the direction of the open-pit mine advancement; When the mining length of the original sidewall step on the upper layer of the sidewall step group exceeds 50m, the coal of the original sidewall step on the lower layer of the sidewall step group will be mined starting from the side of the dump in the open-pit mine and along the direction of the open-pit mine advancement;

[0008] Pressure wall dumping: When the mining distance of the original end wall step below the wall step group reaches the minimum working flat width of the open-pit mine, the dumping yard is formed starting from one side of the open-pit mine and the lowest layer of the coal seam step is used for dumping. The dumping height is the height of the wall step group, and the dumping width is twice the width of the original end wall step.

[0009] Furthermore, in the wall expansion and mining step, a minimum transport road width is maintained between the topmost original end wall step in the topmost wall expansion step group and the pressure release step group.

[0010] Furthermore, in the wall expansion and mining step, the mining of the upper original end wall step in each wall expansion step group must advance the mining of the lower original end wall step, and the advance distance is equal to the width of the end wall safety plate.

[0011] Furthermore, in the sidewall mining step, during the process of mining the original end sidewall steps on the upper layer of the sidewall step group, the top width of the original end sidewall steps on the upper layer after mining should be maintained to be no less than the minimum working flat plate width.

[0012] Furthermore, in the wall expansion mining step, the mining distance of the upper wall expansion step group is not less than 30m ahead of the mining distance of the lower wall expansion step group.

[0013] Furthermore, in the sidewall mining step, the mining of the original end sidewall step on the upper layer of the sidewall step group lags behind the mining of the lowest original end sidewall step in the lowest sidewall expansion step group by no less than 30m.

[0014] Compared with the prior art, the present invention divides the process of mining by leaning against the wall into stages, and timely implements the internal drainage of the pressure wall, which greatly shortens the existence time of the steep slope after leaning against the wall, and can not only mine coal by leaning against the wall, but also maintain the stability of the slope. The step grouping and staggered mining scheme realizes the staged and step-by-step implementation of leaning against the wall mining, avoiding the concentrated impact on the stability of the end wall caused by the previous leaning against the wall method. Pressure-releasing mining not only realizes the early mining of the upper coal seam during the leaning against the wall, avoiding the excessive requirements of concentrated mining on the capacity of mining equipment, but also releases the pressure on the steps of the lower coal seam, increasing the stability of the lower steps. The process of expanding the wall mining not only realizes the leaning against the wall mining of local steps, but also prepares resources and space in advance for the final leaning against the wall mining. The present invention can carry out leaning against the wall mining on at least 5 steps, with considerable output and good economic benefits. The step grouping scheme also ensures the smooth transportation road of the upper end wall of each group of steps, avoiding the impact of leaning against the wall within the group on mine transportation. The implementation process of the present invention is independent of the open-pit mine working side mining, the internal dump can discharge soil normally, the impact on coal mine production is relatively small, and there is no need to purchase additional equipment or train personnel, the feasibility is high, and the benefit is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the pressure release mining stage of the present invention;

[0016] Figure 2 This is a schematic diagram of the expansion and mining stage of the present invention;

[0017] Figure 3 This is a schematic diagram of the mining stage of the present invention;

[0018] Figure 4 This is a schematic diagram of the soil pressing and discharging stage of the present invention;

[0019] Figure 5 for Figure 1 Schematic diagram of the middle AA section;

[0020] Figure 6 for Figure 1 Schematic diagram of the middle BB section;

[0021] Figure 7 for Figure 2 Schematic diagram of the middle CC section;

[0022] Figure 8 for Figure 3 Schematic diagram of the middle DD section;

[0023] Fig. 9 for Figure 4 Schematic diagram of the middle EE section;

[0024] Fig.10 for Figure 4 Schematic diagram of the middle FF section;

[0025] In the figure: 1-end wall rock and soil step; 2-coal seam step; 3-original end wall step; 4-pressure relief step group; 5-back wall step group; 6-expanded wall step group; 7-open pit mine dump; 8-open pit mine advancement direction; 9-pressure relief mining working face; 10-coal quantity of the lower step in the pressure relief group; 11-step transportation passage; 12-expanded wall mining working face; 13-coal quantity of each step in the expanded wall group; 14-first back wall working face; 15-second back wall working face; 16-coal quantity of all steps in the back wall group; 17-pressure wall dump; 18-open pit mine working face. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings.

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] The present invention provides a technical solution, including four steps: pressure relief mining, wall expansion mining, wall leaning mining and wall pressure dumping; Figure 5 and Figure 6 As shown, the end wall rock and soil step 1 is kept unchanged, and according to the order of the coal seam steps 2, the top two original end wall steps 3 of the coal seam steps 2 are divided into a pressure relief step group 4, and the bottom two original end wall steps 3 of the coal seam steps 2 are divided into a back wall step group 5, and the coal seam steps 2 between the pressure relief step group 4 and the back wall step group 5 are divided into multiple wall expansion step groups 6 with 2-3 layers of original end wall steps 3 as a group.

[0029] Pressure relief mining: Figure 1 , Figure 5 and Figure 6 As shown, starting from one side of the spoil dump 7 in the open-pit mine, a pressure relief mining working face 9 is arranged on the original end wall step 3 of the lower layer of the pressure relief step group 4, and along the open-pit mine advancement direction 8, the coal of the original end wall step 3 of the lower layer of the pressure relief step group 4 is mined, and the original end wall step 3 of the upper layer of the pressure relief step group 4 remains in its original state; with the continuous advancement of the open-pit mine working face 18, the pressure relief mining is also continuously carried out, and finally the two layers of original end wall steps 3 of the pressure relief step group 4 are merged into one layer.

[0030] The end wall pressure coal mined during the pressure relief mining stage is the amount of coal 10 on the lower step in the pressure relief group. The purpose of pressure relief mining is to mine the coal on the original end wall step 3 of the lower layer of the pressure relief step group 4 while maintaining the upper step transportation passage 11 uninterrupted, to achieve local leaning in advance, and more importantly, to reduce the pressure above the leaning step group 5 and the expanded wall step group 6, which helps to maintain stability of the two. The end wall slope angle does not change during the pressure relief mining stage.

[0031] Expansion mining: Figure 2 and Figure 7 As shown, when the pressure relief mining length exceeds 50m, starting from one side of the spoil dump 7 in the open-pit mine, the wall expansion mining working face 12 is arranged on the 2-3 layers of original end wall steps 3 in the top-level wall expansion step group 6, and the coal of all the original end wall steps 3 in the top-level wall expansion step group 6 is mined along the open-pit mine advancement direction 8. The minimum transportation road width is maintained between the topmost original end wall step 3 in the top-level wall expansion step group 6 and the pressure relief step group 4 to ensure that transportation vehicles can pass. The mining of the upper layer of original end wall step 3 in the wall expansion step group 6 must be ahead of the mining of the lower layer of original end wall step 3. The optimal leading distance is equal to the width of the end wall safety plate to ensure the normal mining work. With the continuous advancement of the pressure relief mining above, the wall expansion mining also continues to advance. After the top-level wall expansion step group 6 advances more than 50m, the second-level wall expansion step group 6 below it starts to be mined according to the steps of the top-level wall expansion step group 6, and similarly, it is mined in sequence until the bottom-level wall expansion step group 6; during the wall expansion mining process, the mining distance of the upper-level wall expansion step group 6 must be kept ahead of the mining of the lower-level wall expansion step group 6 by no less than 30m.

[0032] The end wall pressure coal mined during the wall expansion mining stage is the amount of coal 13 in each step of each layer of the wall expansion group. While maintaining the continuous transportation passage of the upper steps in each layer of the wall expansion step group 6, the wall expansion mining can mine the coal of the original end wall steps 3 in each layer of the wall expansion step group 6, and realize local wall mining in advance; at the same time, the wall expansion mining of the lowest wall expansion step group 6 also prepares resources and space for the next step of wall group mining; the end wall slope angle does not change during the wall expansion mining stage.

[0033] Mining by helping: Figure 3 , Figure 8 and Fig. 9As shown, when the mining length of the lowest wall expansion step group 6 exceeds 50m, the first wall working face 14 is arranged on the original end wall step 3 on the upper layer of the wall expansion step group 5, starting from one side of the spoil dump 7 in the open-pit mine, and the coal of the original end wall step 3 on the upper layer of the wall expansion step group 5 is mined along the advancing direction 8 of the open-pit mine. During the mining process, the top width of the original end wall step 3 on the upper layer after mining should be kept not less than the minimum working flat plate width to ensure that the equipment on the wall expansion step group 6 above it can operate normally. With the continuous advancement of the upper wall expansion step group 6, the wall mining is also continuously advanced, but the original end wall step 3 on the upper layer of the wall expansion step group 5 should be kept The mining of the side step 3 lags behind the mining distance of the lowest original end side step 3 in the lowest expanded side step group 6 by no less than 30m, and the angle of the end side slope remains unchanged at this time; when the mining length of the original end side step 3 on the upper layer of the side step group 5 exceeds 50m, a second side step working face 15 is arranged on the original end side step 3 of the lower layer of the side step group 5 starting from one side of the spoil dump 7 in the open-pit mine, and the coal of the original end side step 3 of the lower layer of the side step group 5 is mined along the advancement direction 8 of the open-pit mine, that is, the lowest coal mining step of the entire open-pit mine, and the top width of the original end side step 3 of the lower layer after mining is kept at the minimum working flat plate width during the mining process.

[0034] The end wall pressure coal mined in the wall mining stage is the amount of coal 16 of all steps in the wall group. The purpose of the wall mining is to realize the wall mining of two steps in stages, which reduces the construction time of each stage. Before the original end wall step 3 of the lower layer is mined, the slope angle of the end wall of the entire open-pit mine remains unchanged, realizing the recovery of coal resources while maintaining the stability of the end wall. The advantage of the staged implementation is that the slope angle increases only when the original end wall step 3 of the lower layer is mined, which reduces the exposure time of the steep end wall and ensures the stability of the end wall.

[0035] Pressing and discharging soil: Figure 4 and Fig.10 As shown, when the mining distance of the original end wall step 3 of the lower layer of the back wall step group 5 reaches the distance of the minimum working flat plate width of the open-pit mine, starting from one side of the dump 7 in the open-pit mine, the dump 17 is formed by dumping soil from the lowest layer of the coal seam step 2. The dumping height is the height of the back wall step group 5, and the dumping width is twice the width of the original end wall step 3. The lower end wall exposed after the back wall mining is buried in time, and as the back wall mining is continuously advanced, the dump 17 is also continuously followed up, so as to always keep the exposure time of the end wall after the back wall mining as short as possible, so as to avoid or reduce the adverse effects on the stability of the end wall.

[0036] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any slight modification, equivalent substitution and improvement made to the above embodiment based on the technical essence of the present invention should be included in the protection scope of the technical solution of the present invention.

Claims

1. A method for mining thick coal seam open-pit mines based on time-dependent slopes, characterized in that: The method comprises four steps of pressure relief mining, wall expansion mining, wall support mining and wall pressure removal; the top two layers of original end wall steps (3) of the coal seam step (2) are divided into a pressure relief step group (4); the bottom two layers of original end wall steps (3) of the coal seam step (2) are divided into a wall support step group (5); the coal seam step (2) between the pressure relief step group (4) and the wall support step group (5) is divided into a plurality of wall expansion step groups (6) according to 2-3 layers of original end wall steps (3) as a group; Pressure relief mining: starting from one side of the spoil dump (7) in the open-pit mine, along the open-pit mine advancement direction (8), the coal of the original end wall step (3) of the lower layer of the pressure relief step group (4) is mined, and the original end wall step (3) of the upper layer of the pressure relief step group (4) is mined to maintain the original state; as the open-pit mine working face (18) continues to advance, the pressure relief mining is also continuously carried out, and finally the two layers of the original end wall step (3) of the pressure relief step group (4) are merged into one layer; Expanded wall mining: when the depressurization mining length exceeds 50m, starting from one side of the spoil dump (7) in the open-pit mine, along the open-pit mine advancement direction (8), the coal of all the original end wall steps (3) in the topmost expanded wall step group (6) is mined; after the topmost expanded wall step group (6) is advanced for more than 50m, the second layer of expanded wall step group (6) below it begins to be mined according to the steps of the topmost expanded wall step group (6), and the above mining steps are repeated, and mining is carried out in sequence until the bottommost expanded wall step group (6); Sidewall mining: When the mining length of the lowest sidewall step group (6) exceeds 50m, starting from one side of the open-pit mine dump (7), along the open-pit mine advancement direction (8), the coal of the original sidewall step (3) on the upper layer of the sidewall step group (5) is mined; when the mining length of the original sidewall step (3) on the upper layer of the sidewall step group (5) exceeds 50m, starting from one side of the open-pit mine dump (7), along the open-pit mine advancement direction (8), the coal of the original sidewall step (3) on the lower layer of the sidewall step group (5) is mined; Pressure wall dumping: When the mining distance of the original end wall step (3) below the side wall step group (5) reaches the minimum working plate width of the open-pit mine, starting from one side of the dumping yard (7) in the open-pit mine, the dumping starts from the lowest layer of the coal seam step (2) to form a pressure wall dumping yard (17). The dumping height is the height of the side wall step group (5), and the dumping width is twice the width of the original end wall step (3).

2. The method for mining thick coal seam open-pit mines based on time-dependent slope according to claim 1, characterized in that: In the wall expansion and mining step, a minimum transport road width is maintained between the uppermost original end wall step (3) in the topmost wall expansion step group (6) and the pressure relief step group (4).

3. The method for mining thick coal seam open-pit mines based on time-dependent slope according to claim 1, characterized in that: In the wall expansion mining step, the mining of the upper original end wall step (3) in each wall expansion step group (6) must be ahead of the mining of the lower original end wall step (3), and the leading distance is equal to the width of the end wall safety plate.

4. The method for mining thick coal seam open-pit mines based on time-dependent slope according to claim 1, characterized in that: In the sidewall mining step, during the process of mining the original end sidewall step (3) on the upper layer of the sidewall step group (5), the top width of the original end sidewall step (3) on the upper layer after mining should be maintained to be no less than the minimum working plate width.

5. The method for mining thick coal seam open-pit mines based on time-dependent slope according to claim 4 is characterized by: In the wall expansion mining step, the mining of the upper wall expansion step group (6) is ahead of the mining of the lower wall expansion step group (6) by no less than 30m.

6. The method for mining thick coal seam open-pit mines based on time-dependent slope according to claim 1, characterized in that: In the sidewall mining step, the mining of the original end sidewall step (3) on the upper layer of the sidewall step group (5) lags behind the mining of the lowest original end sidewall step (3) in the lowest sidewall expansion step group (6) by no less than 30 m.

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