An open pit mine deep notch invasive mining method

Abstract

This invention discloses an invasive mining method for deep-pit open-pit mines, comprising three main steps: over-stripping and over-drainage, horizontal pushing and internal drainage, and top-mining reverse drainage. In the over-stripping process, the originally inclined goaf floor is transformed into a horizontal one, creating internal drainage conditions for mining the entire depressed area and reducing external drainage volume and costs. In the over-drainage process, excess stripped material is temporarily stored within the mining area, and subsequent internal drainage can be achieved through reverse drainage, avoiding land resource occupation caused by external drainage. Horizontal pushing and internal drainage achieves horizontal advancement of the depressed area, restoring the management mode to its pre-depression state, reducing management difficulty, avoiding overhead or downward mining, and improving equipment utilization efficiency. In the top-mining reverse drainage process, the secondary stripping and over-drainage waste dump is backfilled into the depressed area, balancing the stripping ratio and drainage space, fully utilizing mine equipment capacity, and avoiding safety issues caused by idle goaf areas. By adjusting the temporal and spatial correlation between mining, stripping, and drainage, various problems currently faced when mining through depressed areas are avoided.

Description

Technical Field

[0001] This invention relates to an open-pit mining method, specifically an invasive open-pit mining method for deep pit mines. Background Technology

[0002] Due to crustal movement, coal seams that were originally nearly horizontally distributed have formed a distribution pattern in some areas or even over a large area, with a central depression and upward dipping on both sides, resembling a "√" shape. When open-pit mining is used to extract coal resources in this area, it forms the deep-depression open-pit mine described in this invention. When mining in this area, the following problems will arise: First, an imbalance in waste disposal space. Conventional open-pit mining uses the coal seam floor as the boundary. If this traditional method is continued in the depression, when the depression angle of the coal seam floor exceeds 20 degrees, the floor no longer has the conditions for internal waste disposal. This will result in the inability to achieve internal waste disposal before the open-pit mine passes the lowest point of the depression, with the stripped material occupying land. After passing the lowest point, the space in the depression goaf is rapidly released, but the stripped material is insufficient to fill it, causing regional safety issues. Second, an imbalance in the stripping ratio. After mining passes the lowest point of the depression, the coal seam gradually dips upward, and the amount of stripping decreases rapidly. Compared to before passing the lowest point, the stripping ratio decreases significantly, posing challenges to mine management. Third, there is an imbalance in equipment utilization efficiency. With the imbalance in the stripping ratio, in order to ensure the output of open-pit mines, a large number of various excavation and transportation equipment need to be used in the early stage, but in the later stage, it causes serious redundancy in equipment capacity. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides an invasive mining method for deep open-pit mines. By adjusting the temporal and spatial relationships between mining, stripping, and dumping, it avoids imbalances in dumping space, stripping-to-mining ratio, and equipment utilization efficiency.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for invasive mining of deep open-pit mines, comprising the following steps:

[0005] Over-stripping: When the open-pit mine working line advances to the starting point of the depression, the original working side of the open-pit mine gradually increases the slope angle to the maximum slope angle by adding steep slopes and merging sections, and maintains this angle for advancement; from the starting point of the depression, the working bench of the open-pit mine begins to extend vertically downward, forming a depression end side on the side of the original inner spoil heap, forming a depression working side in the depression area, and connecting with the original working side.

[0006] The concave end wall intrudes into the rock strata below the coal seam floor. On the basis of maintaining the minimum pit bottom width distance between the lowest step of the concave end wall and the lowest step of the concave working wall, the two walls continue to extend downward until they reach the horizontal position of the lowest point of the concave coal seam and then stop concave, at which point a horizontal open-pit mine pit bottom is formed.

[0007] Over-discharge: The stripping material produced during the over-stripping process is discharged along the direction of open-pit mine advancement, starting from the over-discharge point, forming an over-discharge spoil heap;

[0008] Horizontal Advance: The concave working face and the original working face advance horizontally and continuously in the direction of open-pit mine advancement, mining the concave coal seam, stripping the stripped material in the concave area, and continuously widening the bottom width of the open-pit mine along the direction of open-pit mine advancement;

[0009] Internal discharge: As the bottom of the open-pit mine continues to widen, the internal discharge site is constructed layer by layer from the bottom of the open-pit mine along one side of the concave end. The stripped material during the flat-pushing process is directly discharged into the internal discharge site, thus realizing the internal discharge of stripped material.

[0010] Upward mining: After the horizontal push and internal drainage are completed, the open-pit mine continues to advance, and the lowest step of the concave working side begins to be arranged closely to the bottom of the coal seam and gradually moves upward.

[0011] Reverse dumping: During the mining process, a large amount of space in the open-pit mine's subsided goaf is released. At this time, the secondary stripping over-dumping dump is used, and the material from the secondary stripping is transported in the reverse direction and backfilled into the subsided goaf.

[0012] Furthermore, the super-discharge point is calculated as the contact point between the concave working face and the ground surface, starting from the lowest point of the concave coal seam and along the direction of open-pit mine advancement, based on the maximum working face slope angle.

[0013] Furthermore, the recessed spoil heap gradually rises and eventually connects with the original spoil heap to form an integrated spoil heap.

[0014] Furthermore, the horizontal pushing and internal discharge continues until the lowest step of the concave working side reaches the lowest point of the concave coal seam. At this point, the original working side has just advanced to the over-discharge point, and the horizontal pushing and internal discharge stops.

[0015] Furthermore, when the extraction begins, the original working tool has just advanced to the position of the over-discharge point.

[0016] Compared with existing technologies, this invention transforms the originally inclined goaf floor into a horizontal one during the over-stripping process, creating internal dumping conditions for mining the entire concave area, reducing external dumping volume and lowering dumping costs. During the over-dumping process, excess stripping material is temporarily stored within the mining area, and subsequent internal dumping can be achieved through reverse dumping, avoiding land resource occupation caused by external dumping. The horizontal push-inward dumping achieves horizontal advancement of the concave area, restoring the management mode to its pre-concave-area state, reducing management difficulty, avoiding overhead or downward mining, and improving equipment utilization efficiency. During the upward mining reverse dumping process, the secondary stripping over-dumping dump is backfilled into the concave area, balancing the stripping ratio and dumping space, fully utilizing mining equipment capacity, and avoiding safety issues caused by idle goaf areas. This invention effectively avoids various problems encountered when crossing concave areas as described in the background art by adjusting the temporal and spatial relationships of mining, stripping, and dumping. The implementation process of this invention is easy to understand and operate, and does not add additional difficulty to mine production management. Attached Figure Description

[0017] Figure 1 This is a cross-sectional view of an open-pit mine during the over-stripping and over-drainage stage of this invention;

[0018] Figure 2 This is a cross-sectional view of the open-pit mine during the horizontal push-inward drainage stage of this invention;

[0019] Figure 3 This is a cross-sectional view of the open-pit mine during the reverse drainage stage of this invention;

[0020] In the diagram: 1-Open-pit mine advance direction; 2-Depressed coal seam; 3-Depressed starting point; 4-Depressed ending point; 5-Original spoil heap; 6-Original working side; 7-Depressed end side; 8-Depressed working side; 9-Rock strata below the coal seam floor; 10-Lowest point of the depressed coal seam; 11-Open-pit mine bottom; 12-Over-discharge point; 13-Over-discharge spoil heap; 14-Depressed inner spoil heap. Detailed Implementation

[0021] The invention will now be further described with reference to the accompanying drawings.

[0022] 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.

[0023] like Figures 1 to 3As shown, this invention provides a technical solution comprising three steps: over-stripping and over-dumping, horizontal internal dumping, and upward mining reverse dumping. First, several concepts are defined for ease of subsequent solution description. Following the open-pit mine's advancing direction 1, the position where the open-pit mine working line first contacts the concave coal seam 2 is called the concave starting point 3, and the final contact position is called the concave ending point 4. The dumping ground before the open-pit mine working line advances to the concave starting point is called the original dumping ground 5, and the working face above the line connecting the concave starting point 3 and the concave ending point 4 is called the original working face 6.

[0024] Super peeling:

[0025] When the open-pit mine working line advances to the concave starting point 3, the original working slope 6 of the open-pit mine gradually increases the slope angle to the maximum slope angle through the method of steep slope addition and merging, and maintains this angle for advancement. The specific angle varies depending on the open-pit mine geology and coal seam overburden conditions, usually between 25° and 40°. Starting from the concave starting point 3, the open-pit mine working bench begins to extend vertically downward, forming the concave end slope 7 on the side of the original inner spoil heap, forming the concave working slope 8 in the concave area, and connecting with the original working slope 6.

[0026] The boundary of the concave end slope 7 is no longer defined by the traditional coal seam floor, but extends downwards by the maximum slope angle of the end slope. The specific angle is determined according to the geological conditions, and is generally not less than 25° and greater than the concave dip angle of the coal seam. As a result, the concave end slope 7 intrudes into the rock strata 9 below the coal seam floor, and compared with the traditional mining method, the stripping material is over-stripped.

[0027] While maintaining the minimum pit bottom width distance between the lowest step of the concave end 7 and the lowest step of the concave working 8, the two sides continue to extend downwards until they reach the horizontal position of the lowest point 10 of the concave coal seam, at which point the concavation stops, forming a horizontal open-pit mine bottom 11.

[0028] With this, the over-stripping was completed. During the extension process of the two sides, the coal resources were mined simultaneously, and the stripping material below the coal seam floor was over-stripped.

[0029] Super-emission:

[0030] Starting from the lowest point 10 of the concave coal seam, along the open-pit mine advancing direction 1, the contact point between the concave working face 8 and the surface is calculated according to the maximum working face slope angle and is taken as the over-discharge point 12. Since the over-stripping process cannot achieve internal discharge, the stripping material produced by the over-stripping process is discharged along the open-pit mine direction starting from the over-discharge point 12, forming the over-discharge waste dump 13. Since the over-discharge waste dump 13 is ahead of the original working face 6, it has prematurely invaded the future mining area of ​​the open-pit mine, which is the over-discharge.

[0031] Flat push:

[0032] The concave working side 8, together with the original working side 6, continues to advance horizontally in the direction of open-pit mine advancement 1, mining the concave coal seam 2, stripping the stripped material in the concave area, and continuously widening the width of the open-pit mine bottom 11 along the direction of open-pit mine advancement 1.

[0033] Inner row:

[0034] As the bottom of the open-pit mine 11 is widened, a recessed inner spoil disposal site 14 is constructed layer by layer from the bottom of the open-pit mine 11 along one side of the recessed end wall 7. The stripped material during the flat pushing process is directly discharged into the recessed inner spoil disposal site 14, thus realizing the internal discharge of stripped material.

[0035] As the inner spoil heap 14 gradually rises, it eventually connects with the original spoil heap 5, forming an integrated spoil heap. The horizontal pushing of the inner spoil heap continues until the lowest step of the inner working face 8 reaches the lowest point 10 of the inner coal seam. At this point, the original working face 6 has just advanced to the over-discharge point 12, and the horizontal pushing of the inner spoil heap stops.

[0036] Shangcai:

[0037] After the internal drainage is completed, the open-pit mine continues to advance. At this time, as the concave coal seam 2 begins to gradually dip upward, the lowest bench of the concave working side 8 begins to be arranged close to the bottom of the coal seam and gradually moves upward, that is, the lowest bench gradually moves upward to form the upper mining.

[0038] Reverse Drainage: During the upward mining process, a large amount of space in the sunken goaf of the open-pit mine is released. The upward mining process can produce a large amount of coal with less stripping. If only the stripping material formed by the original strata above the coal seam is stripped, it will not be enough to fill the sunken goaf. At this time, the stripping material in the over-stripping and over-drainage step begins to play its role. When the upward mining begins, the original working face 6 has just advanced to the position of the over-drainage point 12. As the upward mining continues, the original working face 6 advances. At this time, the secondary stripping and over-drainage spoil heap 13 begins. The material from the secondary stripping is transported in reverse and backfilled into the sunken goaf, making full use of the huge goaf space formed during the sunken process and realizing the reverse drainage of the over-drainage spoil heap 13.

[0039] As mining progressed, the goaf in the depression area was completely filled, and the open-pit mine reverted to the normal mining and drainage process that preceded the depression.

[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 method for invasive mining of deep open-pit mines, characterized in that, Includes the following steps: Over-stripping: When the open-pit mine working line advances to the position of the concave starting point (3), the original working side (6) of the open-pit mine gradually increases the slope angle to the maximum slope angle by the steep side and the parallel section method, and maintains this angle for advancement; starting from the concave starting point (3), the open-pit mine working step begins to extend vertically downward, forming a concave end side (7) on the side of the original inner spoil dump, forming a concave working side (8) in the concave area, and connecting with the original working side (6); The concave end wall (7) intrudes into the rock strata (9) below the bottom plate of the coal seam. The two sides continue to extend downwards on the basis of maintaining the minimum pit bottom width distance between the lowest step of the concave end wall (7) and the lowest step of the concave working wall (8) until they reach the horizontal position of the lowest point (10) of the concave coal seam, and then stop concave, thus forming a horizontal open-pit mine bottom (11). Over-discharge: The stripping material produced during the over-stripping process is discharged along the open-pit mine advance direction (1) starting from the over-discharge point (12) to form an over-discharge dump (13); the over-discharge point (12) is the contact point between the concave working face (8) and the ground surface calculated according to the maximum working face slope angle, starting from the lowest point (10) of the concave coal seam along the open-pit mine advance direction (1); Horizontal push: The concave working side (8) and the original working side (6) advance horizontally and continuously in the direction of open-pit mine advancement (1) to mine the concave coal seam (2), strip off the stripped material in the concave area, and continuously widen the width of the bottom (11) of the open-pit mine along the direction of open-pit mine advancement (1); Internal discharge: As the bottom of the open-pit mine (11) widens, the inner discharge soil field (14) is constructed layer by layer from the bottom of the open-pit mine (11) along the side of the concave end (7). The stripped material during the flat pushing process is directly discharged into the inner discharge soil field (14) to realize the internal discharge of stripped material. Upper mining: After the flat push and internal drainage is completed, the open-pit mine continues to advance, and the lowest step of the concave working side (8) begins to be arranged close to the bottom plate of the coal seam and gradually moves upward; Reverse discharge: During the mining process, a large amount of space in the open-pit mine's subsided goaf is released. At this time, the secondary stripping super-discharge dump (13) is used to transport the secondary stripping material back to the subsided goaf.

2. The method for invasive open-pit mining of deep pit mines according to claim 1, characterized in that, The recessed inner spoil disposal area (14) gradually rises and eventually connects with the original spoil disposal area (5) to form an integrated spoil disposal area.

3. The method for invasive open-pit mining of deep pit mines according to claim 1, characterized in that, The flat-push inward discharge continues until the lowest step of the concave working side (8) reaches the lowest point (10) of the concave coal seam. At this time, the original working side (6) has just advanced to the over-discharge point (12), and the flat-push inward discharge stops.

4. The method for invasive open-pit mining of deep pits according to claim 1, characterized in that, When the upper mining begins, the original working tool (6) is just advanced to the position of the over-discharge point (12).

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