A method for zonal mining of a thick and inclined coal seam

Abstract

The application discloses a method for zoned mining of a super-thick inclined coal seam, which comprises the steps of zoned construction, "eight"-shaped internal dumping, external dumping backfilling and longitudinal mining to transverse mining, etc.; the whole open-pit mine realizes longitudinal mining to transverse mining, only the coal seam in the shallow area is mined in the initial construction stage, the stripping ratio is small, the investment can be recovered as soon as possible, the mining of the deep area and the shallow area is combined, and the stripping ratio is balanced; the internal dumping after the mining of the coal seam with a large inclination angle is realized, the external dumping land occupation is greatly reduced, the external dumping land is firstly established and then backfilled, the open-pit mining is completed without the external dumping land, the internal dumping material is not removed twice in the mining process, and the stripping cost is small; the internal dumping land is constructed in a pseudo-inclined mode, safety is ensured, the working lines are arranged staggeredly, the nearest transportation distance from the internal dumping land is kept, and the internal dumping cost is low.

Description

Technical Field

[0001] This invention relates to a method for the construction and mining of open-pit mines, specifically a method for the zoned mining of extremely thick inclined coal seams. Background Technology

[0002] The dip angle of coal seams has a significant impact on open-pit mining procedures and the internal disposal of overburden. Based on domestic experience in developing inclined coal seams, the initial mining process typically employs a strike-grooving, dip-advancing approach. This approach offers significant advantages such as minimal infrastructure investment and rapid construction. However, it also presents challenges, including difficulties in constructing internal waste disposal sites and the large land area required for external waste disposal sites, significantly impacting the long-term benefits of resource development and the extent of ecological disturbance. Northwest my country contains numerous thick, inclined coal seams that are shallow, have low average stripping ratios, and offer significant development benefits. With the westward shift of the national coal development focus, the efficient development of these resources is crucial for ensuring national energy security and improving the economic efficiency of coal enterprises. However, the traditional longitudinal mining procedure is still used for the thick, inclined coal seams, making the construction and stability assurance of the internal waste dump more difficult and having a significant impact on open-pit mining: First, a large amount of stripping material is discharged in the early stages of open-pit mining, and the waste dump occupies a large amount of land; second, the large stripping ratio and the large elevation of the stripping material discharge during deep mining lead to poor economic benefits of resource development. When mining in sections or phases along the dip, the materials discharged in the early stages need to be stripped again in the deep sections, which further worsens the resource development effect; third, the internal discharge volume is insufficient in the later stages of open-pit mining, leaving huge pits after the end of resource development, which are difficult to restore and reuse, and also bring geological disaster risks to the mining area. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a method for zoned mining of thick, inclined coal seams, which achieves internal drainage in open-pit mines while maintaining a balanced stripping ratio, thereby improving mine safety and mining efficiency.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for zoned mining of a very thick inclined coal seam, comprising the following steps:

[0005] S1: Delineate the open-pit mining boundary according to the principle that the production stripping ratio is equal to the economically reasonable stripping ratio n, and determine the dip boundary and strike boundary in sequence according to the occurrence conditions of the coal seam. The position where the stripping ratio of the upper boundary of the coal seam is n is the deep and shallow boundary. The area with a stripping ratio greater than n is the deep area, and the area with a stripping ratio less than n is the shallow area.

[0006] S2: Select an initial location on the strike boundary of the open-pit mine, dig a trench along the strike to form the first working line, and advance the first working line along the dip to form mining area one;

[0007] S3: The side closer to the initial position and the dip boundary is the short side of the strike, and the side farther away is the long side of the strike; outside the open-pit mine boundary adjacent to the short side and the long side of the strike, the short side external spoil disposal site and the long side external spoil disposal site shall be established respectively.

[0008] S4: When mining zone 1 advances to the boundary between the deep and shallow parts, while maintaining the original working line and direction of advancement, establish a second working line and a third working line on the short side and the long side of the strike respectively, and advance in three directions at the same time. Mining zone 2 is formed on the short side of the strike in the shallow part, and mining zone 3 is formed on the long side of the strike in the shallow part.

[0009] S5: After continuing to advance into the deeper area of ​​mining zone 1 to the deep boundary, the advance is stopped. Working lines are established on the short side of the strike and the long side of the strike of the deep area respectively, and mining of the coal seam in the deep area begins.

[0010] S6: When the final length of the pit bottom formed in mining area 1 reaches the working line required for the construction of the inner spoil dump, take the midpoint of the deep boundary of mining area 1 as the starting point, and the shallow boundaries of mining areas 2 and 3 as the ending points, and construct the spoil dump working line of the "eight"-shaped inner spoil dump at a certain pseudo-inclination angle with the bottom plate of the coal seam. The inclination angle of the pseudo-inclination angle is less than the inclination angle of the bottom plate of the coal seam and not greater than the stable slope angle of the inner spoil dump.

[0011] S7: The strike length of mining area 2 is short and the advance speed is high, so it will reach the strike boundary quickly. The remaining amount of mining and stripping in the deep area on the short side of the strike is called the short side coal pillar. The recovery is accelerated by advancing in both directions along the strike in the deep area and along the dip in mining area 2. The working line of the "eight"-shaped inner spoil heap follows the coal seam mining in sync, and the material of the short side outer spoil heap is gradually reversed to the "eight"-shaped inner spoil heap according to the stripping and dumping relationship to avoid leaving the mine pit at the end.

[0012] S8: After the backfilling of the short side spoil heap is completed, all working lines on the side of the short side are closed. At this time, only the shallow working line of mining zone 3 and the deep working line of mining zone 1 after turning are left. At this time, the advancing direction of the two working lines has changed from advancing along the dip in the early stage of open-pit mine construction to advancing along the strike, realizing the transformation of open-pit mine from longitudinal mining to transverse mining.

[0013] Furthermore, the length of the first working line in step S2 should satisfy the requirement that the length of the coal mining working line when advancing to the boundary between the deep and shallow parts of mining area 1 is greater than the minimum pit bottom width.

[0014] Furthermore, in step S3, the length of the shorter side of the path is not less than one time the shortest working line length, not less than the minimum width of the open-pit mine bottom, and not greater than 0.5 times the reasonable truck transport distance.

[0015] Furthermore, in step S8, the working line for mining zone three and the deep working line after turning in mining zone one advance forward in an alternating manner.

[0016] Furthermore, in step S6, before constructing the figure-eight shaped inner spoil heap, the bottom plate of the coal seam is roughened, and trenches 0.5-1.0 meters deep are dug at intervals of 2-3 meters. A material with strong water absorption is laid in the trenches to reinforce the foundation of the spoil heap.

[0017] Compared with existing technologies, this invention initially mines only the shallow part of the coal seam, resulting in a small stripping ratio and low production costs, allowing for rapid investment recovery. Subsequently, it achieves a complete shift from longitudinal to transverse mining in open-pit mines, combining deep and shallow mining to balance the stripping ratio and improve overall development efficiency. In the early stages of open-pit mining, three working sides operate simultaneously, enabling production to be achieved with a shorter initial working line length, thus reducing the initial working line length, lowering the amount of infrastructure stripping, and shortening the construction period. Through the "eight"-shaped internal spoil heap and the shift from longitudinal to transverse mining, it achieves... The current method of internal stripping of overburden after steeply inclined coal seam mining significantly reduces the land occupied by external stripping. The external stripping site is built first and then backfilled, achieving the goal of minimizing the number of external stripping sites and residual mining pits after open-pit mining ends, and eliminating secondary stripping of materials during mining, resulting in low stripping costs. The pseudo-inclination construction of the internal stripping site with the coal seam floor reduces the apparent dip angle of the stripping work line, ensures the safety of the internal stripping site slope, and promotes the early internal stripping of overburden. The staggered arrangement of the work line according to the coal seam occurrence conditions increases the bench capacity of the internal stripping site, reduces the internal stripping transport distance, and keeps internal stripping costs low. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the partition construction process of the present invention;

[0019] Figure 2 for Figure 1 Schematic diagram of resource occurrence at section AA;

[0020] Figure 3 This is a schematic diagram of the construction process of the external spoil disposal site according to the present invention;

[0021] Figure 4 This is a schematic diagram of the construction process of mining zone two and mining zone three of this invention;

[0022] Figure 5 This is a schematic diagram of the construction of the "eight"-shaped internal spoil heap of the present invention;

[0023] Figure 6 This is a schematic diagram of the vertical-to-horizontal mining conversion of the present invention;

[0024] In the diagram: 1. Coal seam dip, 2. Dip boundary, 3. Strike boundary, 4. Deep area, 5. Shallow area, 6. Coal seam, 7. Mining area 1, 8. Short strike side, 9. Long strike side, 10. Short side external spoil heap, 11. Long side external spoil heap, 12. Mining area 2, 13. Mining area 3, 14. Short side coal pillar, 15. "Eight" shaped internal spoil heap, 16. First working line, 17. Deep and shallow boundary, 18. Second working line, 19. Third working line. Detailed Implementation

[0025] The invention will now be further described with reference to the accompanying drawings.

[0026] 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.

[0027] This invention provides a technical solution, which includes steps such as zoned construction, combined deep and shallow mining, "eight"-shaped internal drainage, external drainage backfilling, and conversion from vertical to horizontal mining.

[0028] Zoned construction, such as Figure 1 and Figure 2 As shown:

[0029] S1: Delineate the open-pit mining boundary according to the principle that the production stripping ratio is equal to the economically reasonable stripping ratio n, and determine the dip boundary 2 and strike boundary 3 of the open-pit mining in sequence according to the occurrence conditions of coal seam 6. The position of the stripping ratio n at the dip boundary of coal seam 6 is the deep and shallow boundary 17, the area with a stripping ratio greater than n is the deep area 4, and the area with a stripping ratio less than n is the shallow area 5.

[0030] S2: On the strike boundary of the open-pit mine, select a section with a small stripping ratio, a small dip angle of the coal seam floor, and proximity to the railway loading line as the initial trenching location. Trench along the strike to form the first working line 16. Advance along the first working line 16 to form mining zone 7. During mining, the length of the surface working line remains constant. Therefore, the length of the first working line 16 should satisfy the requirement that the length of the coal mining working line at the deep / shallow boundary 17 of mining zone 7 is greater than the minimum pit bottom width. This can be determined by the following formula:

[0031] L>H1 / tanβ1+H2 / tanβ2+W,

[0032] In the formula: L is the length of the first working line 16, m; H1 is the height of the side slope of the short side 8 at the boundary between the surface and the deep / shallow parts of mining area 7, m; β1 is the angle of the side slope of the short side 8, °; H2 is the height of the side slope of the long side 9 at the boundary between the surface and the deep / shallow parts of mining area 7, m; β2 is the angle of the side slope of the long side 9, °; W is the minimum working line length that meets the requirements of the layout of the open-pit mine's mining, transportation, drainage and other systems, m.

[0033] S3: The side closer to the dip boundary at the initial trench location is the short side of the strike (8), and the side farther from the dip boundary is the long side of the strike (9). Outside the open-pit mine boundary adjacent to both the short side of the strike (8) and the long side of the strike (9), adjacent dump sites 10 and 11 are established nearby to facilitate local dumping and separate coal and rock transport, simplifying the open-pit mine's transportation system layout. The dump capacity is determined based on terrain conditions and mine backfilling needs, prioritizing the needs of the short side dump site 10. That is, under unrestricted terrain conditions, the capacity of the short side dump site 10 should meet the following requirements:

[0034] V1≤H*(H / tanβ3+H / tanβ4)*(H / tanβ5+H / tanα) / 6,

[0035] In the formula: V1 is the capacity of the short-side external spoil heap of the open-pit mine, in m³. 3 H represents the final mining depth of the short side 8 of the open-pit mine, in meters; β3 represents the final end slope angle of the short side 8, in degrees; β4 represents the final slope angle of the inner spoil heap of the short side 8, in degrees; β5 represents the final working slope angle of the short side 8, in degrees; α represents the dip angle of the coal seam floor, in degrees.

[0036] The outer spoil heap 11 should preferably be designed as a rectangle parallel to the long side 9 to facilitate later transport to the inner spoil heap. Its capacity should meet the following requirements:

[0037] V2≥V*k s -V1

[0038] In the formula: V2 is the capacity of the long side of the open-pit mine's external spoil heap 11, in m³. 3 V represents the total amount of stripping material discharged from the open-pit mine, in meters. 3 ;k s The loosening coefficient is the amount of stripped material at the external spoil disposal site.

[0039] The length of the short side 8 shall not be less than one time the shortest working line length, not less than the minimum width of the bottom of the open-pit mine, and not greater than 0.5 times the reasonable truck transport distance.

[0040] The main purposes of setting parameters such as trench length, initial position coal seam 6 dip direction length, and strike short side 8 length are: first, to achieve balanced stripping during the mining stage; second, to ensure sufficient space in subsequent mining areas; third, to ensure construction space for subsequent internal spoil heaps; and fourth, to reduce the transportation distance during early external spoil heaping and later backfilling, thereby ensuring the economic efficiency of the external spoil heaping and backfilling process.

[0041] Combined deep and shallow mining and the transition from vertical to horizontal mining, such as Figure 3 and Figure 4 As shown:

[0042] S4: When mining zone 1 7 advances to the boundary between the shallow and deep sections 17, while maintaining the original working line and direction of advancement, establish a second working line 18 and a third working line 19 on the side of the short strike side 8 and the side of the long strike side 9, respectively. Simultaneously advance in three directions, forming mining zone 2 12 on the side of the short strike side 8 of the shallow section 5, and mining zone 3 13 on the side of the long strike side 9 of the shallow section 5. The total length of the three working lines should meet the design production capacity requirements of the open-pit mine.

[0043] (L1*v1+L2*v2+L3*v3)*h*γ*k c ≥Q,

[0044] In the formula: L1 is the length of the first working line 16, m; v1 is the advancing speed of the first working line 16, which is constrained by both the advance rate of the open-pit mine working face and the deepening speed of the inclined coal seam, and is taken as the maximum value during production, m / a; L2 is the length of the second working line 18, m; v2 is the advancing speed of the second working line 18, which is mainly constrained by the advance rate of the open-pit mine working face and the selective mining of the inclined coal seam, and is taken as close to the maximum value during production, m / a; L3 is the length of the third working line 19, m; v3 is the advancing speed of the third working line 19, which is constrained by the advance rate of the open-pit mine working face and the selective mining of the inclined coal seam, and is determined according to the production capacity requirements during production, m / a; h is the thickness of coal seam 6, m; γ is the bulk density of raw coal, t / m³. 3 ;k c denoted as , where is the recovery rate of the raw coal face; Q is the designed production capacity of the open-pit mine, in tons per year (t / a). With this, the zoning construction work is complete.

[0045] S5: During the advance of mining zone 7 towards deep zone 4, the length of the working line at the bottom of the pit remains unchanged to facilitate the layout of the production system and ensure the production capacity of the open-pit mine. After mining reaches the deep boundary, the advance is stopped. Working lines are established on the short side 8 and the long side 9 of the strike of deep zone 4, respectively. The working side of the open-pit mine turns to mine the coal seam 6 of deep zone 4, and combines with mining zone 2 12 and mining zone 3 13 to realize the overall transformation of the open-pit mine from vertical mining to horizontal mining.

[0046] The inner arrangement is in the shape of the number "8". Figure 5 As shown:

[0047] S6: When the final length of the pit bottom formed in mining area 7 reaches the required length for constructing the inner spoil heap, within the areas of mining area 7, mining area 12, and mining area 13, starting from the midpoint of the deep boundary of mining area 7, and ending at the shallow boundaries of mining area 12 and mining area 13 respectively, and forming a certain pseudo-inclination angle with the bottom plate of coal seam 6, the spoil heap working lines of the inner spoil heap 15 are constructed in a figure-eight shape using stripping material. The certain pseudo-inclination angle refers to the inclination angle of the spoil heap being less than the inclination angle of the coal seam bottom plate and not greater than the stable slope angle of the inner spoil heap, generally not greater than 10°.

[0048] The dumping steps of the "eight"-shaped inner dumping ground 15 will gradually increase in number as the working walls of the three mining areas advance, until the stripped material can be completely dumped internally. Preferably, before the construction of the "eight"-shaped inner dumping ground 15, the bottom plate of the coal seam 6 will be roughened, i.e., "roughened". At intervals of 2-3 meters, trenches 0.5-1.0 meters deep will be dug with a loosening plow, and materials with strong water absorption, water storage and drainage capacity (such as coarse sand, fly ash, lime, etc.) will be laid in the trenches to strengthen the foundation of the dumping ground. The main purpose is to increase the friction coefficient of the bottom plate of the coal seam 6 and reduce the influence of water, thereby improving the stability of the inner dumping ground.

[0049] After mining the shallow zone 5 coal seam 6 on the side of the short side 8 in mining zone 2 12, the deep zone 4 coal seam 6 on the side of the short side 8 will be left behind. As mining zone 1 7 in the previous step turns to start mining the deep zone 4 coal seam 6 on the side of the short side 8, mining continues until the boundary of the open-pit mine is reached, and the short side coal pillar 14 is recovered.

[0050] External backfilling and longitudinal mining to transverse mining, such as Figure 5 and Figure 6 As shown:

[0051] S7: Mining Zone 2 12 has a short strike length and a high advance speed, so it will quickly reach the strike boundary 3. The remaining amount of mining and stripping in Deep Zone 4 on the short side 8 of the strike is called the short side coal pillar 14. Deep Zone 4 is advanced along the strike and Mining Zone 2 12 is advanced along the dip to accelerate recovery. The working line of the "eight"-shaped inner spoil heap 15 is followed synchronously with the mining of coal seam 6, and the material of the short side outer spoil heap 10 is gradually reversed to the "eight"-shaped inner spoil heap 15 according to the stripping and dumping relationship to avoid leaving the mine pit at the end.

[0052] S8: After the backfilling of the short side outer spoil heap 10 is completed, all working lines on the side of the short side 8 are closed. At this time, only the shallow working line of mining zone 3 13 and the deep working line of mining zone 1 7 after turning are left. At this time, the advancing direction of the two working lines has changed from advancing along the dip in the early stage of open-pit mine construction to advancing along the strike, realizing the transformation of open-pit mine from longitudinal mining to transverse mining.

[0053] Because the number of mining benches in deep zone 4 and shallow zone 5 is different, the deep working line after turning in mining zone 1 7 will lag behind the working line of mining zone 3 13 for a long time. Therefore, the inner spoil heap needs to maintain a pseudo-inclined angle to shorten the internal dumping distance of the stripped material and improve the capacity of the spoil heap bench and the stability of the slope. At the same time, according to the stripping and dumping relationship during the open-pit mining and the need for mine area topography restoration, the material of the long side outer spoil heap 11 will be gradually dumped to the inner spoil heap 15 along with the stripped material of the working side, freeing up the land occupied by the outer spoil heap and restoring the strata and landform of the mine area.

[0054] 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.

[0055] 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 zonal mining of a thick and inclined coal seam, characterized in that, The method comprises the following steps: S1: according to the principle that the production stripping ratio is equal to the economic reasonable stripping ratio n, the open-pit mining boundary is delineated, and the dip boundary (2) and the strike boundary (3) are determined in sequence according to the occurrence conditions of the coal seam (6); the position of the open-pit mining boundary in the dip direction of the coal seam (6) with the stripping ratio n is the deep-shallow boundary (17); the area with the stripping ratio greater than n is the deep area (4); and the area with the stripping ratio less than n is the shallow area (5); S2: an initial position is selected on the strike boundary of the open-pit mine, a ditch is drawn along the strike to form a first working line (16), and the first working line (16) is advanced along the dip direction to form a mining area (7); S3: the side of the initial position closer to the dip boundary is a strike short side (8), and the side farther from the dip boundary is a strike long side (9); a short-side external dump (10) and a long-side external dump (11) are respectively established outside the open-pit mine boundary close to the strike short side (8) and the strike long side (9); S4: when the mining area (7) is advanced to the deep-shallow boundary (17), a second working line (18) and a third working line (19) are respectively established on the side of the strike short side (8) and the side of the strike long side (9) on the basis of maintaining the original working line and the advancing direction, and are simultaneously advanced in three directions; a mining area (12) is formed on the side of the strike short side (8) in the shallow area (5), and a mining area (13) is formed on the side of the strike long side (9) in the shallow area (5); S5: the mining area (7) continues to be advanced to the deep area (4) and then stops advancing after reaching the deep boundary; working lines are respectively established on the side of the strike short side (8) in the deep area (4) and the side of the strike long side (9) in the deep area (4) to start mining the coal seam (6) in the deep area (4); S6: when the length of the final slope of the pit bottom formed by the mining area (7) reaches the length required for constructing an internal dump working line, the midpoint of the deep boundary of the mining area (7) is taken as a starting point, the shallow boundaries of the mining area (12) and the mining area (13) are taken as ending points, and an internal dump (15) working line in the shape of an "8" is constructed at a certain pseudo-inclination angle with the coal seam (6) floor; the inclination angle of the pseudo-inclination angle is less than the coal seam floor inclination angle and not greater than the internal dump stable slope angle; S7: the strike length of the mining area (12) is small, and the advancing speed is large, so the mining area (12) will soon reach the strike boundary (3); the remaining mining and stripping amount of the deep area (4) on the strike short side (8) is called a short-side coal pillar (14); the deep area (4) is advanced along the strike and the mining area (12) is advanced along the dip to speed up the recovery; the working line of the internal dump (15) in the shape of an "8" is followed up with the mining of the coal seam (6); and the materials in the short-side external dump (10) are gradually transferred to the internal dump (15) in the shape of an "8" according to the stripping ratio relationship, so as to avoid leaving a final pit; S8: after the short-side external dump (10) is backfilled, all the working lines on the side of the strike short side (8) are closed; at this time, only the shallow working line of the mining area (13) and the deep working line after the mining area (7) is turned are left; at this time, the advancing directions of the two working lines have changed from the dip direction in the initial stage of the open-pit mine construction to the strike direction, so the longitudinal mining of the open-pit mine is changed to the horizontal mining.

2. The method according to claim 1, characterized in that: The length of the first working line (16) in step S2 should meet the length of the working line for mining a first zone (7) to the boundary (17) between the shallow and deep parts, which is greater than the minimum pit floor width.

3. The method for zonal mining of a thick and inclined coal seam according to claim 1, characterized in that: The length of the short side (8) in step S3 should not be less than one time the shortest working line length, not less than the minimum pit floor width, and not greater than 0.5 times the reasonable truck transport distance.

4. The method for zonal mining of a thick and inclined coal seam according to claim 1, characterized in that: The working line of the third zone (13) and the deep working line after the turning of the first zone (7) in step S8 are staggered and advanced forward.

5. The method for zonal mining of a thick and inclined coal seam according to claim 1, characterized in that: The "figure-eight" shaped inner dump (15) in step S6 is first treated by roughening the floor of the coal seam (6) before construction, 0.5-1.0 meter deep grooves are drawn every 2-3 meters, and strong water-absorbing material is laid in the grooves to strengthen the dump base.

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