The method of mining with staged drilling followed by filling is suitable for ore bodies with unstable thickness

Abstract

The present invention discloses a method for mining with empty field and subsequent filling in the stage of segmented rock drilling, which is suitable for ore bodies with unstable thickness. The mining area of ​​the stope of the ore block is divided into regions based on the thickness of the lower segmented ore body, and the lower segmented ore body and the ore body located directly above the lower segmented ore body are divided into the core area ore body, and the ore body located on both sides of the ore body directly above the lower segmented ore body are divided into the peripheral area ore body; firstly, the core area ore body is preferentially mined and the ore is cleared, and then the segmented structure directly below the peripheral area ore body is independently mined and the waste rock is cleared, and finally the peripheral area ore body is mined and the ore is cleared. By step-by-step mining of the core area ore body, the lower segmented structure directly below the peripheral area ore body, and the peripheral area ore body, the ore in the core area ore body and the peripheral area ore body and the waste rock in the lower segmented structure directly below the peripheral area ore body are independently and separately mined, so as to achieve ore-waste separation and reduce the dilution loss rate of the stope.

Description

Technical Field

[0001] The invention relates to the technical field of mining and filling, in particular to a mining method for emptying and subsequently filling in a segmented rock drilling stage suitable for ore bodies with unstable thickness. Background Art

[0002] At present, for steeply inclined, thick and large-scale ore bodies with stable rock, the method of mining with positive step segmented drilling and subsequent empty site filling is generally adopted. By arranging segmented drilling tunnels in the height direction of the mining area, and then drilling upward fan-shaped medium-deep holes, the ore is collapsed from the top to the bottom segmented positive steps. The collapsed ore is concentrated and discharged from the mining trench arranged in the bottom segment. After the mining is completed, the empty area of ​​the mining area is filled with tailings to maintain the ground pressure of the mining area. This is very suitable for the situation where the thickness of the ore body is relatively stable at the stage, but it is extremely unreasonable for the situation where the ore body is thick in the upper part and narrow in the lower part in the stage height direction. When the upper segment mining boundary exceeds a certain distance from the adjacent lower segment, the bottom trench will be insufficiently mined and a large amount of collapsed ore will accumulate on the bottom plate of this segment. At this time, if the bottom structure length or the segment mining boundary is extended to the upper segment mining boundary according to conventional mining practices, the ore depletion rate of the mining field will be greatly increased. If it is not extended in time, a large amount of ore will be accumulated at the level of the segment bottom plate. If a remote-controlled shovel loader is used to enter the segment bottom plate to clean up the remaining accumulated ore, it may easily cause the equipment to fall into the lower segment or the bottom structure, which is not conducive to the safe production of the mine. At the same time, it greatly affects the ore discharge efficiency of the mining field and even causes serious depletion losses in the entire mining field.

[0003] The invention patent with patent application number CN201610784137.X discloses a mining method for spatial reconstruction of gently inclined, thick and lean ore bodies. The method utilizes the mining spatial reconstruction method to construct two high-strength horizontal isolation layers in the gently inclined, thick and lean ore bodies. The horizontal isolation layers are then used as boundaries to vertically divide the gently inclined, thick and lean ore bodies into three blocks: upper, middle and lower. The ore bodies are spatially reconstructed into three blocks: a gently inclined ore body, an inclined ore body and a steeply inclined ore body. The gently inclined ore body in the upper block is mined by the open-field method or the filling method, and the inclined ore body in the middle block and the steeply inclined ore body in the lower block are mined by the caving method. In the above scheme, the caving method is adopted for the steeply inclined ore body. When the upper segment mining boundary exceeds a certain distance from the adjacent lower segment, it is inevitable that the bottom trench will have insufficient mining area and a large amount of collapsed ore will accumulate on the bottom plate of this segment. Therefore, the problem of increased mining depletion rate in the mining field will also occur due to extending the bottom structure length or the segment mining boundary to the upper segment mining boundary.

[0004] In view of the above problems, it is urgent to develop an inclined ore body filling mining method that can reduce the depletion loss rate of unstable thickness ore bodies. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the present invention provides a segmented rock drilling stage empty site followed by filling mining method suitable for ore bodies with unstable thickness, which can separately mine ore and waste rock, achieve ore-waste separation, and reduce the depletion loss rate of the mining site.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is to provide a segmented rock drilling stage empty field and subsequent filling mining method suitable for ore bodies with unstable thickness, which comprises the following steps:

[0007] The stope is divided into sections according to the middle section of the ore body, and each middle section is divided into three sections: upper, middle and lower;

[0008] The mining area of ​​the block is divided into regions based on the thickness of the lower segmented ore body. The lower segmented ore body and the ore body located directly above the lower segmented ore body are divided into core area ore bodies, and the ore bodies located on both sides of the ore body directly above the lower segmented ore body are divided into peripheral area ore bodies.

[0009] First, the ore body in the core area is mined and the ore is cleared first, then the segmented structure directly below the ore body in the peripheral area is mined independently and the waste rock is cleared, and finally the ore body in the peripheral area is mined and the ore is cleared.

[0010] Preferably, in the process of mining the segmented structure directly below the ore body in the peripheral area, the mining boundaries of adjacent segments gradually shrink from top to bottom.

[0011] Preferably, the mining boundaries of adjacent segments differ by the spacing distance of a row of blastholes.

[0012] Preferably, the mining boundary of the lower segment is a steep slope that gradually decreases from top to bottom.

[0013] Preferably, the core area ore body is mined from top to bottom using a staged rock drilling followed by backfill mining.

[0014] Preferably, the recovery progress between two adjacent sections in the core area differs by the spacing distance of two rows of blastholes.

[0015] Preferably, upward fan-shaped medium-deep holes are used to blast and recover the ore body in the core area.

[0016] Preferably, the ore bodies in the peripheral areas of the upper and middle sections are mined synchronously from top to bottom.

[0017] Preferably, annular medium-deep holes are used to simultaneously mine the ore bodies in the outer areas of the upper and middle sections.

[0018] Preferably, upward fan-shaped medium-depth holes are used to recover the lower segmented structure directly below the ore body in the peripheral area.

[0019] The beneficial effects of the present invention are:

[0020] The present invention divides the mining area of ​​the mine field of the ore block into regions based on the thickness of the lower segmented ore body, divides the lower segmented ore body and the ore body located directly above the lower segmented ore body into the core area ore body, and divides the ore bodies located on both sides of the ore body directly above the lower segmented ore body into the peripheral area ore body; by step-by-step mining of the core area ore body, the lower segmented structure directly below the peripheral area ore body, and the peripheral area ore body, the ore in the core area ore body and the peripheral area ore body and the waste rock in the lower segmented structure directly below the peripheral area ore body are independently and separately mined, thereby realizing ore-waste separation and reducing the depletion loss rate of the mine field.

[0021] The present invention adopts a down-the-hole drill to drill annular medium-depth holes in the ore bodies in the outer areas of the upper and middle sections when recovering the ore bodies in the outer areas, and carries out synchronous blasting and caving of the upper and middle sections. The caving ore is concentratedly discharged from the receiving cuttings arranged in the bottom sections, thereby improving the mining efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a long-axis longitudinal projection diagram of the mining method of empty-site and subsequent filling in the stope in the stage of segmented rock drilling suitable for ore bodies with unstable thickness as described in an embodiment of the present invention.

[0023] Figure 2 for Figure 1 Cross-sectional view of II-II.

[0024] Figure 3 for Figure 1 Cross-sectional view of III-III.

[0025] Figure 4 for Figure 1 Cross-sectional view of section IV-IV.

[0026] The markings of the components in the accompanying drawings are as follows:

[0027] 1. Boundary of the top pillar of the mining area; 2. Final boundary of the mining area; 3. Ore body in the core area; 4. Upward fan-shaped medium-deep holes; 5. Circular medium-deep holes; 6. Collapsed ore; 7. Downward fan-shaped medium-deep holes; 8. Segmented rock drilling tunnels; 9. Receiving tunnels; 10. Mine access roads; 11. Transport tunnels; 12. Mine exit tunnels; 13. Segmented horizontal tunnels; 14. Ore body boundary; 15. Segmented ramps; 16. Ore trenches; 17. Waste rock trenches; 18. Ore body in the peripheral area; 19. Rock body in the ore-fall compensation area; 20. Filling and rock drilling tunnels. DETAILED DESCRIPTION

[0028] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0029] The present invention provides a method for mining with empty pits and subsequent filling in the stage of segmented rock drilling, which is suitable for ore bodies with unstable thickness, and comprises the following steps:

[0030] S1. Divide the stope into sections according to the middle section of the ore body, and divide each middle section into three sections: upper, middle and lower;

[0031] S2. Divide the mining area of ​​the block into regions based on the thickness of the lower segmented ore body, divide the lower segmented ore body and the ore body directly above the lower segmented ore body into core area ore body 3, and divide the ore bodies on both sides of the ore body directly above the lower segmented ore body into peripheral area ore body 18;

[0032] S3. First, the core area ore body 3 is mined and the ore is removed first, then the segmented structure directly below the peripheral area ore body 18 is mined and the waste rock is removed independently, and finally the peripheral area ore body 18 is mined and the ore is removed.

[0033] By dividing the ore blocks into regions, the core area ore body 3, the lower segmented structure directly below the peripheral area ore body 18, and the peripheral area ore body 18 are mined in steps, so that the ore in the core area ore body 3 and the peripheral area ore body 18 and the waste rock in the lower segmented structure directly below the peripheral area ore body 18 can be mined separately, thereby realizing ore-waste separation and reducing the depletion loss rate of the mining area.

[0034] Specific as Figures 1 to 4 As shown, the middle section of the ore block is divided into three sections from top to bottom: upper, middle and lower, wherein a top column is left at the bottom of the upper section; the contour line of the ore body in the lower section is used as a reference to vertically divide the core area ore body 3 and the peripheral area ore body 18, that is, the maximum width along the contour line of the ore body in the lower section is the thickness of the ore body in the core area, and the ore body in the lower section ore body and the ore body in the core area ore body thickness corresponding to the upper and lower parts of the lower section ore body in the upper and middle sections are divided into the core area ore body 3, and the ore body on both sides of the core area ore body 3 in the upper and middle sections are divided into the peripheral area ore body 18.

[0035] After the regional division, Figures 1 to 3 As shown, the core area ore body 3 is first mined first, and the core area ore body is mined from top to bottom by using the segmented rock drilling stage and subsequent backfill mining method, that is, the core area ore body 3 of the upper, middle and lower segments is mined by the positive step method from top to bottom, and the difference in the mining progress between two adjacent segments is the spacing distance of two rows of blastholes. Figure 1 and Figure 2 As shown, when mining the core area ore body 3 of the upper, middle and lower sections, a drilling rig is used to drill upward fan-shaped medium-deep holes 4 for blasting mining, and the ore is collapsed section by section from top to bottom. The collapsed ore 6 is concentrated and mined from the receiving ore trench arranged in the lower section.

[0036] The lower structure of the ore body 18 in the peripheral area is the rock mass 19 in the ore compensation area. After the collapsed ore 6 in the core area is cleared, the lower structure of the ore body 18 in the peripheral area, i.e. the rock mass 19 in the ore compensation area, is excavated to increase the mining area of ​​the bottom trench and avoid the problem of a large amount of collapsed ore 6 accumulating on the bottom plate of this section. Specifically, in the process of recovering the rock mass 19 in the ore compensation area, in order to realize the downward mining of adjacent upper sections, the final mining boundaries of adjacent sections need to differ by the spacing distance of rows of blastholes, and the mining boundaries of adjacent sections gradually decrease from top to bottom. Figure 1 As shown, the left mining boundary of the middle segment structure is smaller than the left mining boundary of the ore body 18 in the outer area of ​​the upper segment. When the left mining boundary of the upper segment differs from the left mining boundary of the middle segment by the spacing distance of three rows of blastholes, it is necessary to additionally excavate two rows of blastholes to the left in the middle segment directly below the ore body 18 in the left outer area of ​​the upper segment. After additional excavation of the rock mass 19 in the ore drop compensation area of ​​the middle segment, the left mining boundary of the middle segment structure is smaller than the left mining boundary of the ore body 18 in the outer area of ​​the upper segment by the spacing distance of one row of blastholes. The left mining boundary of the lower segment structure is smaller than the left mining boundary of the ore body 18 in the peripheral area of ​​the middle segment, and the left mining boundary of the middle segment differs from the left mining boundary of the lower segment by the spacing distance of 6 rows of blastholes. Then, the lower segment directly below the ore body 18 in the left peripheral area of ​​the middle segment is additionally excavated to the left by the spacing distance of 5 rows of blastholes, and after the additional excavation of the rock mass 19 in the ore drop compensation area of ​​the lower segment, the left mining boundary of the lower segment structure is smaller than the left mining boundary of the ore body 18 in the peripheral area of ​​the middle segment by the spacing distance of 1 row of blastholes. It is preferred to use the upward fan-shaped medium-deep hole 4 to mine the rock mass 19 in the ore drop compensation area.

[0037] After the compensation area is mined, the peripheral area ore body 18 is mined. Since the compensation area has not been filled after mining, at this time, Figure 3 As shown, the area directly below the outer area ore body 18 in the middle section is mined out. At this time, a down-the-hole drill is used in the segmented rock drilling tunnel 8 of the upper section to drill annular medium-deep holes 5 in the outer area ore bodies 18 of the upper and middle sections, and the upper and middle sections are blasted synchronously to collapse the ore. The collapsed ore 6 is concentrated and discharged from the mining trench arranged in the bottom section.

[0038] After all areas have been mined, build retaining walls, hang filling hoses and filter pipes, and use 1:4 to 1:8 full tailings cementation to fill the empty areas.

[0039] To further illustrate the segmented rock drilling stage empty field subsequent filling mining method suitable for unstable thickness ore bodies proposed by the present invention, a copper-nickel mine in Xinjiang, my country, which is controlled by the secondary fracture and crushing zone of the regional Huangshan deep fault zone, is taken as an example. Its ore deposit is produced in the No. Ⅰ basic-ultramafic complex, and the ore-bearing rocks are mainly hornblende pyroxene, hornblende pyroxene and hornblende gabbro. The ore body is layered, veined, and cystic, extending in the NE-SW direction, with a length of more than 740 meters, and has the phenomenon of expansion, contraction, and branching and compounding with the change of rock body morphology. Among them, the narrowing and contraction phenomenon of the ore body is particularly prominent between the 900-850m level. The geological reserves of the middle section of 850m are 1.045 million tons, of which the amount of rich ore accounts for 28%, the amount of industrial ore accounts for 71%, the average grade of Cu is 0.73%, the average grade of Ni is 1.05%, the amount of Cu metal is 7628.5t, and the amount of Ni metal is 10972.5t. The ore body changes relatively stably along the strike direction, showing the characteristics of thick upper part and narrow lower part. It is a steeply inclined thick ore body with a dip angle of 70° to 80° and an average thickness of 27m. The ore rock conditions are moderately stable, and the joints and fissures are relatively developed.

[0040] (1) Mining site division: a block mining site is divided every 60m along the ore body. The block mining site is arranged vertically, with a width of 15m, a length of the ore body thickness, and a height of 50m. The block mining site adopts a mining-recovery sequence. After the first-step block mining site is recovered, the tailings are cemented and filled with a lime-sand ratio of 1:4 to 1:8. The second-step block mining site is filled with tailings. In order to improve the mining efficiency as much as possible and reduce the dilution loss rate, the 850m middle section ore body is designed to be mined by the segmented rock drilling stage empty site and subsequent filling mining method proposed by the present invention, which is suitable for ore bodies with unstable thickness; the 850m middle section ore body is divided into three sections in height direction, namely, 850m, 865m, and 880m, upper, middle, and lower. The height of each section is 15m. Among them, a top pillar with a height of 8m is reserved in the upper segment mining site.

[0041] (2) Setting up the mining and cutting project: The mining project mainly includes the segmented rock drilling tunnel 8, segmented chute, receiving tunnel, ore exit road 10, ore exit tunnel 12 and related connecting roads. Among them, the segmented rock drilling tunnel 8 mainly provides working space for segmented medium-deep hole rock drilling, charging and blasting operations, and also serves as a transportation channel for personnel, equipment and materials. The tunnel section is 3.0m×3.0m. The segmented chute is mainly used as a ore and slag discharge channel during the excavation of the segmented mining project, with a cross-sectional specification of 1.5m×2.0m. The receiving tunnel is a ore collection tunnel of the bottom structure and an important part of the trench structure. The tunnel section is 3.0m×3.0m. The ore exit tunnel 12 is a part of the bottom structure ore exit system, arranged vertically between two adjacent mining areas, and has a tunnel section of 3.0m×3.0m. As part of the bottom structure mining system, the mining access road 10 is evenly spaced between the mining tunnel and the mining tunnel 12. The distance between the access roads is 12m, and the horizontal angle with the mining tunnel 12 is 45°. The tunnel section is 3.0m×3.0m. The rock drilling tunnel connection road is mainly used as a connecting passage between the segmented rock drilling tunnel 8 and the segmented horizontal tunnel 13, and the tunnel section is 3.0m×3.0m. The chute connection road is used as a connecting passage between the segmented horizontal tunnel 13 and the segmented chute, and the tunnel section is 3.0m×3.0m and the length is 5m.

[0042] like Figure 1 As shown, the cutting project mainly includes segmented cutting tunnels and cutting shafts; the segmented cutting tunnel is arranged in the middle of the segmented stope along the ore body, and is the working space for cutting slot drilling, charging, and blasting. The tunnel section is 4.0m×3.0m, and the length is the width of the stope. The segmented cutting shaft is arranged at the end of the segmented cutting tunnel, mainly to provide free surface and compensation space for the formation of cutting slot blasting, with a section specification of 2.0m×2.0m and a length of 12m.

[0043] (3) Ore recovery: Figures 1 to 4 As shown, the left mining boundary of the upper section is larger than that of the middle section by the spacing distance of three rows of blastholes, the right mining boundary of the upper section is also larger than that of the middle section by the spacing distance of three rows of blastholes, the left mining boundary of the middle section is larger than that of the lower section by the spacing distance of six rows of blastholes, and the right mining boundary of the middle section is larger than that of the lower section by the spacing distance of four rows of blastholes. Therefore, both the middle section and the lower section require additional excavation of rock mass in the ore drop compensation area 19.

[0044] Specifically, firstly, the ore body 3 in the core area is mined by the segmented drilling stage and the subsequent backfilling mining method, and the ore is removed; then, the upward fan-shaped medium-deep hole 4 is drilled to mine the rock body 19 in the ore-drop compensation area in the lower section, and the waste rock is removed; then, based on the ore body 18 in the peripheral area of ​​the middle section, an annular medium-deep hole 5 is drilled in the segmented drilling tunnel 8 of the middle section to mine the ore body 18 in the peripheral area of ​​the middle section, and part of the ore body 18 in the peripheral area of ​​the upper section corresponding to the ore body 18 in the peripheral area of ​​the middle section, and the ore is removed; then, the downward fan-shaped medium-deep hole is drilled to mine the rock body 19 in the ore-drop compensation area of ​​the middle section, and finally, the downward fan-shaped medium-deep hole 7 is drilled in the self-filling and drilling tunnel 20 to mine the remaining peripheral area ore body 18 in the upper section.

[0045] The mining area uses YGZ-90 drilling rigs and KQJ-100B down-the-hole drilling rigs for rock drilling operations. Among them, the YGZ-90 rail-type rock drilling rig with the TJ25 disc-type drill frame is preferably used in the core area ore bodies 3 of the upper, middle and lower sections to carry out the upward fan-shaped medium-deep hole 4 rock drilling operations, with a blasthole diameter of Φ65mm, a blasthole row spacing of 1.4 to 1.6m, and a hole bottom distance of 1.9 to 2.2m. The KQJ-100B down-the-hole drilling rig is used in the outer area ore bodies 18 of the upper and middle sections to carry out the annular medium-deep hole 5 and the downward fan-shaped medium-deep hole 7 rock drilling operations, with a blasthole diameter of Φ100mm, a blasthole row spacing of 1.8 to 2.0m, and a hole bottom distance of 2.7 to 3.1m.

[0046] The BQF-100 type charge charger is used for unified charging. The explosive is powdered ammonium nitrate explosive. The digital electronic detonator is reversely detonated at the bottom of the hole. The hole mouth is blocked at intervals of 1m to 1.5m. 1 to 2 rows are blasted each time.

[0047] (4) Ventilation of the mining area: Fresh air flows from the middle main transport tunnel through the mine exit tunnel 12 and the mine exit access road 10 into the mining area, or from the ramp through the segmented horizontal tunnel 13 and the segmented rock drilling tunnel 8 into the mining area. The dirty air flows from the segmented rock drilling tunnel 8 through the uppermost segmented horizontal tunnel 13 into the middle return air shaft, and finally converges into the main return air shaft and is discharged to the surface.

[0048] (5) Roof management: After the blasting of the mine and effective ventilation to remove the blasting smoke, the safety personnel enter the face to clean the loose floating stones on the roof and the two sides. If the roof and the two sides are still not safe after treatment, anchor spraying or anchor net support shall be carried out in accordance with the corresponding safety regulations of the mine. During the production process, safety inspections shall be strengthened in a timely manner, and problems shall be dealt with on site in a timely manner.

[0049] (6) Mining out of the stope: 2m 3 The shovel loader enters the receiving tunnel 9 from the mine exit road 10 to complete the shoveling operation, unloads the ore to the middle ore chute through the mine exit tunnel 12, and then loads it into the bottom mine car, which is towed by an electric locomotive to the bottom of the mine yard, and finally lifted to the surface by the main shaft cage.

[0050] The above are only embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for mining with a staged rock drilling followed by filling in a ore body with unstable thickness, characterized in that: The steps include: The stope is divided into sections according to the middle section of the ore body, and each middle section is divided into three sections: upper, middle and lower; The mining area of ​​the block is divided into regions based on the thickness of the lower segmented ore body. The lower segmented ore body and the ore body located directly above the lower segmented ore body are divided into core area ore bodies, and the ore bodies located on both sides of the ore body directly above the lower segmented ore body are divided into peripheral area ore bodies. First, the ore body in the core area is mined and the ore is cleared first, then the segmented structure directly below the ore body in the peripheral area is mined independently and the waste rock is cleared, and finally the ore body in the peripheral area is mined and the ore is cleared.

2. The method of mining with subsequent filling in the staged rock drilling process suitable for ore bodies with unstable thickness according to claim 1 is characterized in that: In the process of mining the segmented structure directly below the ore body in the peripheral area, the mining boundaries of adjacent segments gradually narrow from top to bottom.

3. The method of mining with subsequent filling in the staged rock drilling process suitable for ore bodies with unstable thickness according to claim 2 is characterized in that: The mining boundaries of adjacent sections differ by the spacing of a row of blastholes.

4. The method of mining with subsequent filling in the staged rock drilling process suitable for ore bodies with unstable thickness according to claim 1, characterized in that: The mining boundary of the lower section is a steep slope that gradually decreases from top to bottom.

5. The method of mining with subsequent filling in the staged rock drilling process suitable for ore bodies with unstable thickness according to claim 1, characterized in that: The core area ore body is mined from top to bottom using the staged rock drilling and subsequent backfilling mining method.

6. The method of mining with subsequent filling in the staged rock drilling process suitable for ore bodies with unstable thickness according to claim 5, characterized in that: The mining progress between two adjacent sections of the core area ore body differs by the spacing between two rows of blastholes.

7. The method of mining with subsequent filling in the staged rock drilling process suitable for ore bodies with unstable thickness according to claim 5, characterized in that: The core area ore body is mined by blasting using upward fan-shaped medium-deep holes.

8. The method of mining with subsequent filling in the staged rock drilling process suitable for ore bodies with unstable thickness according to claim 1, characterized in that: The ore bodies in the outer areas of the upper and middle sections are mined synchronously from top to bottom.

9. The method of mining with subsequent filling in the staged rock drilling process suitable for ore bodies with unstable thickness according to claim 8, characterized in that: Annular medium-deep holes are used to simultaneously mine the ore bodies in the outer areas of the upper and middle sections.

10. The method of mining with subsequent filling in the staged rock drilling process suitable for ore bodies with unstable thickness according to claim 1, characterized in that: The lower segmented structure directly below the ore body in the peripheral area is mined using upward fan-shaped medium-deep holes.

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