A seasonal open-pit mining method

Abstract

This invention discloses a seasonal open-pit mining method, comprising five steps: advanced stripping, deep trenching, bottom drainage, horizontal stripping and mining, trenching along the mining platform, and preparation for subsequent operations. The invention retains the advanced mining platform to prevent weathering and spontaneous combustion after large-scale coal seam exposure; the total length of multiple horizontal mining lines is not less than the length of the open-pit mine's working lines before the implementation of this invention, ensuring that the open-pit mine's production capacity is not reduced; the pit bottom space is pre-allocated, solving the problem of insufficient drainage space during concentrated stripping and avoiding the problem of longer transport distances for stripped materials during advanced stripping; trenching along the mining platform provides construction space for the next stage of operations; the invention as a whole only re-coordinates the relationship between open-pit mining, stripping, and drainage, and adjusts the mining area space, without fundamentally modifying the mine's production, making construction simple and management easy.

Description

Technical Field

[0001] This invention relates to an open-pit mining method, specifically an open-pit seasonal mining method. Background Technology

[0002] Northwest China experiences cold winters and long freezing periods, leading to high coal demand and rapid open-pit mine development. However, severe permafrost in winter makes stripping operations costly and inconvenient. During non-winter periods, coal demand is lower, and mine development is slower, but higher temperatures facilitate rock stripping. However, these high temperatures also increase the risk of spontaneous combustion of exposed coal. To adapt to different seasonal climates and coal demand, a number of seasonal open-pit mines have emerged in Northwest China. These mines operate year-round, with mining progressing faster in winter than in other seasons. Stripping is typically carried out in spring, summer, and autumn, with stripping ceasing or only minimally occurring in winter. While seasonal mining adapts to the climate and coal market, it also results in insufficient internal drainage space during peak stripping periods (spring, summer, and autumn). Large amounts of exposed coal at the end of autumn, when stripping ceases, are prone to spontaneous combustion. Furthermore, before the start of stripping the following year, the mine pits are wide, resulting in wasted space, long internal haulage distances, and high costs. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a seasonal open-pit mining method that coordinates the relationship between open-pit mining, stripping, and dumping, adjusts the mining area space, ensures open-pit mine production capacity, shortens the transport distance of stripped material, and reduces stripping costs.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for seasonal open-pit mining, comprising five steps: advance stripping, deep trenching, bottom drainage, horizontal stripping and mining, trenching along the mining surface, and preparation for subsequent mining operations.

[0005] Advanced stripping:

[0006] At the start of the concentrated stripping period in open-pit mines, except for the first stripping step above the coal seam, all other stripping steps above the coal seam are stripped ahead of the mine's advance direction at an accelerated pace, forming an advance flat plate above the coal seam. The width of the advance flat plate in the advance direction is greater than or equal to the annual advance rate N of the open-pit mine. The advance stripping should be completed before the end of the concentrated stripping period of the year.

[0007] Groove depth:

[0008] During the advanced stripping process, starting from the bottom of the open-pit mine, along the direction of the open-pit mine advance, a cutting groove is excavated on the advanced flat plate. The cutting groove runs through the entire advanced flat plate and extends to the bottom of the coal seam. The width of the cutting groove on the bottom of the coal seam is not less than the minimum bottom width of the pit.

[0009] Pit bottom drainage:

[0010] The stripping material generated during the advanced stripping and deep grooving steps is directly and locally dumped to the bottom of the open pit, forming a bottom dump. The height of the lowest dumping step of the bottom dump is the same as the height of the coal seam and is completely connected to the coal bench of the coal seam. The bottom dump gradually connects with the dump to form a whole.

[0011] Peeling and harvesting horizontally:

[0012] When winter arrives or the bottom of the open-pit mine is buried and the original working line of the open-pit mine is not ready for mining, when the length of any cut groove reaches the minimum working line length, then starting from that cut groove, lateral stripping working lines are deployed towards the two sides of the open-pit mine end face to strip the stripped material on the advance plate; then lateral mining working lines are deployed to mine the coal below the advance plate.

[0013] Grooves along the edge of the plate:

[0014] During the advancement of the horizontal mining line, a horizontal mining pit bottom is formed in the mined area. When the width of the horizontal mining pit bottom exceeds twice the minimum pit bottom width, the stripping material generated during the horizontal stripping process at the bottom of the horizontal mining pit forms a horizontal mining dump. The horizontal mining dump is connected to the pit bottom dump. A connecting trench is reserved on the side of the horizontal mining dump near the advanced flat plate.

[0015] Next steps:

[0016] At the end of winter, all the coal in the advanced stripping pan is mined out, and the next year's concentrated stripping period begins. The above steps are repeated to complete the mining, stripping and stripping work every year thereafter.

[0017] Furthermore, during the advanced stripping process, the stripping and coal mining steps within the advanced flat plate area advance normally along the open-pit mine's advancing direction, mining the amount of coal required at that moment.

[0018] Furthermore, the number of the cutting grooves n ≥ (L / N) / 2, where N is the annual advance rate of the open-pit mine and L is the original working line length of the open-pit mine.

[0019] Furthermore, when the number of eyelet grooves exceeds one, the eyelet grooves are evenly and equidistantly distributed within the range of the advanced flat plate.

[0020] Furthermore, the width of the connecting channel is the minimum pit bottom width, and its length extends through both sides of the open-pit mine end wall.

[0021] Furthermore, the two steps of horizontal stripping and mining and trenching along the stripping plate are completed before the start of the concentrated stripping period in the following year.

[0022] Compared with existing technologies, this invention retains the advanced flatbed to avoid weathering and spontaneous combustion after large-area exposure of the coal seam; the total length of multiple transverse mining lines is not less than the length of the open-pit mine working lines before the implementation of this invention, which can maintain the open-pit mine's production capacity; the open-pit mine pit bottom space is adjusted and used in advance, which not only solves the problem of insufficient internal drainage space during concentrated stripping, but also avoids the problem of longer transportation distance of stripped material during advanced stripping; the groove left along the flatbed provides construction space for the next process; the invention as a whole only re-coordinates the relationship between open-pit mining, stripping and drainage, and adjusts the mining area space, without making a complete modification to the mining area production, making construction simple and management easy. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the advanced peeling and deep grooving steps of the present invention;

[0024] Figure 2 This is a schematic diagram showing the state of the pit bottom discharge and horizontal stripping and mining steps of the present invention;

[0025] Figure 3 for Figure 2 Schematic diagram of section AA;

[0026] Figure 4 This is a schematic diagram of the horizontal stripping and mining and groove retention steps of the present invention;

[0027] In the diagram: 1-Coal seam; 2-Stripping bench; 3-Open-pit mine advance direction; 4-Advanced leveling plate; 5-Open-pit mine pit bottom; 6-Cut-out slot; 7-Original open-pit mine working line; 8-Pit bottom spoil heap; 9-Spoil heap; 10-Transverse stripping working line; 11-Transverse mining working line; 12-Transverse mining end wall; 13-Transverse mining pit bottom; 14-Transverse mining spoil heap; 15-Connecting slot; 16-Open-pit mine end wall. Detailed Implementation

[0028] The invention will now be further described with reference to the accompanying drawings.

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] like Figures 1 to 4 As shown, the present invention provides a technical solution, which includes five steps: advanced stripping, deep grooving, bottom drainage, horizontal stripping and mining, groove retention along the plate, and subsequent preparation.

[0031] like Figure 1As shown, advanced stripping: At the beginning of the concentrated stripping period of the open-pit mine, that is, when the ground thaws in spring each year, except for the first stripping step 2 above coal seam 1, all other stripping steps 2 above coal seam 1 are accelerated to strip ahead along the advance direction 3 of the open-pit mine, forming an advanced flat plate 4 above coal seam 1. The width of the advanced flat plate 4 in the advance direction should be greater than or equal to the annual advance rate N of the open-pit mine. The annual advance rate N of the open-pit mine is a value that has been determined during the construction of the open-pit mine and generally will not change. Moreover, the value is different for each open-pit mine. The advanced stripping should be completed before the end of the concentrated stripping period of the year, that is, at the end of autumn.

[0032] During the advanced stripping process, the stripping and coal mining benches within the advanced flat plate 4 area advance normally along the open-pit mine advance direction 3, mining the amount of coal required at the moment. The reason why the first stripping bench 2 above coal seam 1 is not subjected to advanced stripping is to cover the coal seam and prevent weathering and spontaneous combustion after a large area of ​​coal seam 1 is exposed.

[0033] Deepening of the cutting groove: During the advance stripping process, starting from the bottom 5 of the open-pit mine, along the advance direction 3 of the open-pit mine, a trench is excavated on the advance platform 4 as a cutting groove 6. The cutting groove 6 extends through the entire advance platform 4 in length and reaches the bottom of the coal seam 1 in depth. The width of the cutting groove 6 on the bottom of the coal seam 1 is not less than the minimum bottom width of the pit. The number n of the cutting groove 6 is determined according to the correlation between the annual advance rate N of the open-pit mine and the length L of the original working line 7 of the open-pit mine, generally n≥(L / N) / 2. The core logic of this relationship is to ensure that the total length of the subsequent transverse mining working line 11 is not less than the length of the open-pit mine working line 7 before the implementation of the plan, thereby maintaining the open-pit mine's production capacity. Furthermore, when the number of cutting grooves 6 exceeds one, they should be evenly and equidistantly distributed within the advance platform 4.

[0034] like Figure 2 and Figure 3 As shown, the waste generated during the advanced stripping and deep grooving steps is directly dumped into the entire area of ​​the open-pit mine bottom 5, forming the bottom waste dump 8. In order to facilitate the secondary stripping construction during the mining of coal seam 1 in the horizontal stripping and mining steps, the height of the lowest waste dump 8 is the same as the height of coal seam 1, and it is completely connected with the coal bench of coal seam 1. The bottom waste dump 8 gradually connects with the waste dump 9 into a whole.

[0035] The purpose of the pit bottom discharge step is to utilize the pit space to discharge stripped materials. Traditional open-pit mining always has pit bottom space for equipment operation. This invention, through the combination of the trenching deepening step, the pit bottom discharge step, and the subsequent horizontal stripping and mining step, pre-allocates the space at the bottom of the open-pit mine 5. Subsequently, multiple small pit bottom spaces are regenerated through the horizontal stripping and mining step. On the one hand, it solves the problem of insufficient discharge space during concentrated stripping. On the other hand, it avoids the problem of longer transport distance of stripped materials during advanced stripping.

[0036] like Figure 4 As shown, horizontal stripping and mining: When winter comes or the bottom 5 of the open-pit mine is buried and the original working line 7 of the open-pit mine is not ready for mining, when the length of any cut groove 6 reaches the minimum working line length, which is generally calculated based on the mining equipment, and the data of each open-pit mine is inconsistent, then the cut groove 6 is used as the starting point, and horizontal stripping working lines 10 are deployed towards the two open-pit mine end walls 16 to strip the stripped material on the advance plate 4; then horizontal mining working lines 11 are deployed to mine the coal below the advance plate 4; one cut groove 6 can form two sets of stripping working lines and coal mining working lines with opposite directions of advancement. During the horizontal stripping and mining process, the original open-pit mine stripping bench 2 and soil dumping bench become the horizontal mining end wall 12.

[0037] Because the bottom dumping process causes the bottom dumping site 8 to connect with the coal seam 1, during the horizontal stripping and mining process, the bottom dumping site 8 connected to the coal seam 1 needs to be stripped a second time to ensure that the coal at the connection point is completely extracted.

[0038] Along the mining platform: During the advancement of the transverse mining working line 11, a transverse mining pit bottom 13 is formed in the mined area. When the width of the transverse mining pit bottom 13 exceeds twice the minimum pit bottom width, the stripped material generated during the transverse stripping process at the transverse mining pit bottom 13 forms a transverse mining dump 14. The transverse mining dump 14 is connected to the pit bottom dump 8. A trench is reserved on the side of the transverse mining dump 14 near the advanced flat 4 as a connecting trench 15. The width of the connecting trench 15 is the minimum pit bottom width, and its length runs through the two open-pit mine end walls 16. Its function is to provide construction space for the next process. The two steps of transverse stripping and mining and along the mining platform are completed before the start of the concentrated stripping period in the following year.

[0039] Preparation for the next step: When winter ends, the coal in the advanced leveling plate 4 is mined out, and the concentrated stripping period of the following year begins. The above steps are followed in this manner to complete the mining, stripping and stripping work for each subsequent year.

[0040] It will be apparent to those skilled in the art that the present 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 its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any minor modifications, equivalent substitutions, and improvements made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A seasonal open-pit mining method, comprising five steps: advance stripping, deep trenching, bottom drainage, horizontal stripping and mining, sidewall trenching, and subsequent preparation. Advanced stripping: At the start of the concentrated stripping period of the open-pit mine, except for the first stripping step (2) above the coal seam (1), all other stripping steps (2) above the coal seam (1) are accelerated to strip ahead along the direction of the open-pit mine advance (3), forming an advance flat plate (4) above the coal seam (1). The width of the advance flat plate (4) in the direction of advance is greater than or equal to the annual advance rate N of the open-pit mine. The advance stripping should be completed before the end of the concentrated stripping period of the year. Groove depth: During the advance stripping process, starting from the bottom of the open-pit mine (5), along the advance direction of the open-pit mine (3), a cutting groove (6) is excavated on the advance plate (4). The cutting groove (6) runs through the entire advance plate (4) and extends to the bottom of the coal seam (1). The width of the cutting groove (6) on the bottom of the coal seam (1) is not less than the minimum bottom width of the pit. Drainage at the bottom of the pit: The stripping material generated during the advanced stripping and deep grooving steps is directly dumped to the entire area of ​​the bottom of the open pit (5) to form the bottom dump (8). The height of the lowest dumping step of the bottom dump (8) is the same as the height of the coal seam (1) and is completely connected with the coal step of the coal seam (1). The bottom dump (8) gradually connects with the dump (9) into a whole. Peeling and harvesting horizontally: When winter comes or the bottom of the open-pit mine (5) is buried and the original working line (7) of the open-pit mine is not ready for mining, when the length of any cut groove (6) reaches the minimum working line length, then starting from the cut groove (6), a transverse stripping working line (10) is deployed towards the two sides of the open-pit mine end wall (16) to strip the stripped material on the advance plate (4); then a transverse mining working line (11) is deployed to mine the coal below the advance plate (4); Grooves along the edge of the plate: During the advancement of the horizontal mining working line (11), a horizontal mining pit bottom (13) is formed in the mined area. When the width of the horizontal mining pit bottom (13) exceeds twice the minimum pit bottom width, the stripping material generated during the horizontal stripping process at the horizontal mining pit bottom (13) forms a horizontal mining dump (14). The horizontal mining dump (14) is connected to the pit bottom dump (8). A connecting trench (15) is reserved on the side of the horizontal mining dump (14) near the advanced flat plate (4). Next steps: At the end of winter, the coal in the advanced flat plate (4) is mined out, and the concentrated stripping period of the following year begins. The mining, stripping and drainage work is completed in the following years by following the above steps.

2. The method for seasonal open-pit mining according to claim 1, characterized in that, During the advanced stripping process, the stripping and coal mining steps within the range of the advanced flat plate (4) advance normally along the open-pit mine advance direction (3) to mine the amount of coal required at the moment.

3. The method for seasonal open-pit mining according to claim 1, characterized in that, The number of the cutting grooves (6) is n≥(L / N) / 2, where N is the annual advance of the open-pit mine and L is the length of the original working line (7) of the open-pit mine.

4. A seasonal open-pit mining method according to claim 3, characterized in that, When the number of eye grooves (6) exceeds one, the eye grooves (6) are evenly and equidistantly distributed within the range of the advanced flat plate (4).

5. A seasonal open-pit mining method according to claim 1, characterized in that, The width of the connecting channel (15) is the minimum bottom width of the pit, and its length extends through the open-pit mine end walls (16) on both sides.

6. A method for seasonal open-pit mining according to claim 1, characterized in that, The two steps of horizontal stripping and mining, and leaving grooves along the stripping plate, shall be completed before the start of the concentrated stripping period in the following year.

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