A safe and efficient mining method for high-stage large-scale stopes in underground metal mines

Abstract

The present invention discloses a safe and efficient mining method for a high-stage, large-scale stope in an underground metal mine, comprising the following steps: S1, dividing the mining area into long and wide mining units along the strike of the ore body; merging two middle sections into high-stage mining; S2, first constructing and completing the bottom trench receiving structure, and then completing the middle section rock drilling chamber from the upper middle section roadway, which is divided into two layers of chambers for downward ore dropping; S3, the ore pillars in the middle section rock drilling chamber adopt a multi-segment small ore pillar structure; S4, constructing reinforcement anchor cable groups from the lower stage rock drilling chambers on both sides of the lower middle section to the adjacent ore rocks of the stope of the adjacent secondary mining units on both sides; S5, mining units. The present invention effectively reduces the concentration of high stress by adjusting the size of the ore pillars in the middle of the stope and the blasting point, and simultaneously strengthens the rock mass by using anchor cable groups, thereby ensuring that the goaf is stable and does not suffer damage during the mining, ore extraction, and filling and mining cycles.

Description

Technical Field

[0001] The present invention relates to the field of metal mining, and in particular to a safe and efficient mining process for large-scale mining sites at advanced stages of metal mines. Background Art

[0002] Deeply buried metal ore bodies are often mined underground due to factors such as the extensive stripping, widespread environmental impact, and economic inequality associated with open-pit mining. For large and extra-large deposits, low-cost open-stop or block-caving methods were often used in previously underdeveloped economies, when environmental awareness was weak, and when there were no residents or critical infrastructure on the surface. With economic development, growing environmental awareness, and the rapid advancement of mining equipment, these mining methods have been gradually replaced by backfill or open-stop and subsequent backfill methods, which minimize environmental impact and maximize solid waste disposal, achieving the optimal outcome of extracting useful ore resources without significant environmental damage.

[0003] The staged empty site and subsequent filling method has the advantages of high mining efficiency and good safety as all personnel work in the chamber. It is widely used in large and extra-large metal mines at home and abroad. However, due to the limitations of rock conditions and ground stress, the length, width and height of the mining site are limited, which reduces mining efficiency and increases mining costs.

[0004] The staged empty stope and subsequent filling method first excavates the bottom of the mine cut (funnel) and the rock drilling chamber, and uses large-diameter deep holes or deep hole downward blasting to recover the ore. The high-stage large-scale stope structure has a large amount of ore retained in each recovery unit, a strong mining capacity, a small unit mining and cutting workload, and a high mining effect. However, the stope structure is large in size, especially the high-stage stope has a large vertical height and large exposed area, which makes it easy for the rock mass on both sides of the long axis of the goaf to fail and become unstable. The rock mass instability poses a safety hazard and is not conducive to the normal recovery of the subsequent stope. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem that the mining stress is concentrated in the middle part of the goaf due to the large vertical height and exposed surface of the large-scale stope in the high-stage underground mining of metal mines, which in turn causes the collapse of ore rocks. It ensures that the goaf is stable and not damaged during the mining, ore extraction and filling and mining cycle, and realizes a method for safe and efficient mining of large-scale stopes in the high-stage.

[0006] The technical solution adopted by the present invention is: a safe and efficient mining method for a large-scale stope at a high stage in an underground metal mine, comprising the following steps:

[0007] S1, divide the mining units into long and wide units along the strike of the ore body; merge the two middle sections into high-stage mining;

[0008] S2, first complete the bottom trench receiving structure, use trackless scrapers to unload the ore, then complete the middle section rock drilling chamber from the upper middle section tunnel, divided into two layers of chambers for downward ore dropping;

[0009] S3, the middle section of the rock drilling chamber adopts a multi-segment small pillar structure. The lateral hanging roof area of the goaf is the cause of concentrated stress, so a multi-segment small pillar structure is adopted to reduce the damage to the chamber roof caused by the roof of the mining unit. High-position blasting drilling is also carried out along the lateral goaf of the working face to eliminate high stress concentration at the source.

[0010] S4, constructing reinforcement anchor cable groups from the lower stage rock drilling chambers on both sides of the lower middle section to the adjacent ore rocks of the secondary mining units on both sides; the reinforcement anchor cable group consists of at least three reinforcement anchor cables, which are respectively inclined upward, horizontal, and downward, forming a "fan" shape; the length of the upward reinforcement anchor cable is slightly longer than the horizontal reinforcement anchor cable, and the downward reinforcement anchor cable is longer than the upward reinforcement anchor cable; the length of the reinforcement anchor cable group penetrating into the rock mass is about half of the width of the mining unit, and the length of the adjacent reinforcement anchor cable groups penetrating into the rock mass is different, and the bottom is opened into a "W" shape; the interval between the reinforcement anchor cable groups is one-quarter of the width of the mining unit; through a group of "fan"-shaped anchor cable groups with "W"-shaped bottoms between groups, a reinforcement body is formed for the lateral middle rock mass to avoid or reduce damage caused by stress concentration;

[0011] S5, the mining unit, first pulls the bottom of the trench to form a lower compensation space, then drops ore from the lower stage drilling chamber of the lower middle section, and then drops ore from the upper stage drilling chamber of the upper middle section to complete the mining; high and low position blasting technology is used when dropping ore to shorten the collapse distance, and at the same time, high position blasting drilling is carried out in the side goaf along the mining face.

[0012] As a further improvement of the present invention, in S1, the length of the mining unit is 75-80m, the width is 25-30m; the height of the single middle section is 50-60m, and the height of the double middle sections is 100-120m.

[0013] As a further improvement of the present invention, the upper inclination angle of the reinforcement anchor cable group is 30-45 degrees, and the lower inclination angle is 45-55. According to research, the breaking angle of most rock formations is approximately 55 degrees and extends upward, so the upper and lower inclination angles of the reinforcement anchor cable group can achieve a good reinforcement effect.

[0014] As a further improvement of the present invention, in the S4, three anchor cables are arranged in a fan shape, the lengths of the adjacent reinforcement anchor cables penetrating into the rock mass are different, and the bottom of the groups are arranged in a "W" shape in an alternating manner. On the basis of the lateral reinforcement bodies with a flat mining surface, the ore rock structure belt and large joint surfaces are effectively avoided.

[0015] As a further improvement of the present invention, radial small conduits are added between the reinforcement anchor cable groups in the middle and lower part. The collapse of the low-lying rock formation will cause a certain disturbance, and the addition of radial small conduits between the reinforcement anchor cable groups can achieve the effect of breaking the top of the low-lying rock formation.

[0016] As a further improvement of the present invention, if the adjacent mining units do not have the conditions for constructing reinforcement anchor cables, the corresponding mining units adopt normal mining height.

[0017] The beneficial effects of this invention include: effectively reducing the concentration of high stress by adjusting the size of the ore pillars in the middle of the stope and the blasting points, while also reinforcing the rock mass with anchor cables, thereby ensuring that the goaf remains stable and undamaged during the mining, ore removal, and backfilling cycles. This also effectively reduces engineering workload and costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic plan view of the lower middle section chamber of the present invention ( Figure 1 for Figure 2 II cross-sectional view)

[0019] Figure 2 for Figure 1 A cross-section along the middle of the mining unit ( Figure 2 for Figure 1 II-II cross-section diagram)

[0020] As shown in the figure: 1. Lower stage drilling chamber, 2. Adjacent ore and rock in the mining area, 3. Reinforcement anchor cable group, 4. Chamber pillars, 5. Frame to be mined, 6. Blasting deep hole, 7. Upper stage drilling chamber. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] A safe and efficient mining method for a large-scale stope at a high stage in an underground metal mine comprises the following steps:

[0023] S1, divide the mining units into long and wide units along the strike of the ore body; merge the two middle sections into high-stage mining;

[0024] S2: First, the bottom trench receiving structure is constructed and the ore is unloaded using a trackless scraper. Then, the middle drilling chamber is completed from the upper middle tunnel. The ore is dropped downwards in two chambers. Ore is temporarily retained in the stope. The unloading of ore meets the compensation space for subsequent blasting. After all blasting is completed, a large amount of ore is unloaded.

[0025] S3, the ore pillars in the middle section of the rock drilling chamber adopt a multi-segment small ore pillar structure to reduce the damage to the chamber roof caused by the mining unit breaking the roof; high-position blasting drilling is carried out along the side of the working face to the goaf to eliminate high stress concentration at the source;

[0026] S4, constructing reinforcement anchor cable groups 3 from the lower stage rock drilling chambers 1 on both sides of the lower middle section to the adjacent ore rocks 2 of the stope of the adjacent secondary mining and recovery units on both sides; the reinforcement anchor cable group consists of at least three reinforcement anchor cables, which are respectively arranged in an upward, horizontal, and downward direction and form a group in a "fan" shape. The length of the upward reinforcement anchor cable is slightly longer than the horizontal reinforcement anchor cable, and the downward reinforcement anchor cable is longer than the upward reinforcement anchor cable; the length of the reinforcement anchor cable group penetrating into the rock mass is approximately half of the width of the recovery unit, and the length of the penetrating rock mass between adjacent reinforcement anchor cable groups is different, and the bottom is opened in a "W" shape; the spacing between the reinforcement anchor cable groups is one-quarter of the width of the recovery unit;

[0027] S5, the mining unit, first digs the bottom trench to form a lower compensation space, then drops ore from the lower stage drilling chamber 1 of the lower middle section, and then drops ore from the upper stage drilling chamber 7 of the upper middle section to complete the mining; high and low position blasting technology is used when dropping ore to reduce the empty top span during the blasting process and form an approximate pressure balance arch. At the same time, high position blasting drilling is carried out along the side goaf of the mining face.

[0028] Theoretical mechanics calculations and practical applications have shown that the stress of high-stage mining in a stope is mainly concentrated in the middle part of the stope void, that is, the middle part of the stope in the long axis direction and near the lower drilling chamber in the vertical direction. Therefore, the middle part of the stope is pre-reinforced to reduce and avoid damage to the stress concentration part, so as to achieve the goal of efficient mining.

[0029] The following combination Figures 1 to 2 , the present invention is further described.

[0030] Example 1, a method for achieving underground high-stage continuous mining, comprising the following steps:

[0031] S1, divided into long and wide mining units along the strike of the ore body, with the two middle sections merged into high-stage mining;

[0032] S2, first complete the bottom trench receiving structure, use trackless scrapers to unload the ore, then complete the middle section drilling chamber from the upper middle section tunnel, and divide it into two layers of chambers for downward ore dropping;

[0033] S3, construct reinforcement lines 3 from the rock drilling chambers 1 on both sides of the lower middle section to the secondary mining unit ore rock 2 on the adjacent two sides;

[0034] S4, reinforcement anchor cable 3 consists of three cables: upward, horizontal and downward, forming a group like a "fan" anchor cable group;

[0035] S5, the upper and lower inclination angles of the anchor cable are 45-55 degrees, and the horizontal length of the anchor cable into the ore rock is half the width of the mining unit, 12-15m;

[0036] S6, the interval between anchor cable groups is half of their horizontal length into the ore rock, i.e. about 6-7.5m;

[0037] S7, the horizontal depth intervals of anchor cable groups into the rock mass are different. For example, the 1st, 3rd and 5th groups penetrate 12m, and the 2nd, 4th and 6th groups penetrate 15m. The bottom of the anchor cable groups are staggered and arranged in a "W" shape on different sides. This effectively avoids the reduction of anchoring force due to structural planes and large joints and fissures in the ore rock at the same bottom, thereby improving the overall anchoring strength.

[0038] S8, by reinforcing the anchor cables 3 to form a "fan" shape within the group, a staggered "W" shape at the bottom between groups, and a flat surface in the open area, effectively prevents the possibility of instability and damage to the side walls due to stress concentration during high-stage stope recovery, providing guarantee for safe mining, ore removal and filling in the stope;

[0039] S9, the adjacent mining units (stopes) do not have the conditions for constructing reinforced anchor cables, so a normal single middle section is adopted, and the mining height is 50-60m above the middle section.

[0040] In a practical application case, a metal mine in Tongling boasts a 60m-high middle section, with a mining unit 80m long, 30m wide, and 120m high. The trench bottom structure is ore-damped, and deep-hole blasting chambers are deployed in both the upper and lower middle sections. Using the aforementioned method, the lower chamber reinforces the middle section of the high side walls with anchor cables at varying intervals, forming a complete reinforcement structure. The bottom structure is initially pulled down to create a free surface for large-hole blasting and provide compensation space. Then, large-diameter deep holes are drilled downwards in the lower and finally upper layers, allowing for ore removal and backfilling in one operation. After the mining unit was completed, no significant collapse or damage occurred along the 120m-long lateral walls on either side. This has been shown to save 1,200 cubic meters of bottom structure engineering and 1,200 meters of additional anchor cable reinforcement. These savings offset costs exceeding 250,000 yuan per two normal mining units (60m high) compared to single-section mining, and shorten construction time by at least three months, resulting in significant economic benefits.

[0041] Those skilled in the art should know that the protection scheme of the present invention is not limited to the above-mentioned embodiments, and various arrangements, combinations and transformations can be made on the basis of the above-mentioned embodiments. Without violating the spirit of the present invention, various transformations of the present invention fall within the protection scope of the present invention.

Claims

1. A safe and efficient mining method for a large-scale stope at a high stage in an underground metal mine, comprising the following steps: S1, divide the mining unit into long and wide units along the strike of the ore body; merge the two middle sections into a high-stage mining; the mining unit is 75-80m long and 25-30m wide; the height of the single middle section is 50-60m, and the height of the double middle sections is 100-120m; S2: First, the bottom trench receiving structure is constructed and the ore is unloaded using a trackless scraper. Then, the middle drilling chamber is completed from the upper middle tunnel. The ore is dropped downwards in two chambers. Ore is temporarily retained in the stope. The unloading of ore meets the compensation space for subsequent blasting. After all blasting is completed, a large amount of ore is unloaded. S3, the ore pillars in the middle section of the rock drilling chamber adopt a multi-segment small ore pillar structure to reduce the damage to the chamber roof caused by the mining unit breaking the roof; high-position blasting drilling is carried out along the side of the working face to the goaf to eliminate high stress concentration at the source; S4, constructing reinforcement anchor cable groups (3) from the lower stage rock drilling chambers (1) on both sides of the lower middle section to the adjacent ore rocks (2) of the stope of the adjacent secondary mining and recovery units on both sides; the reinforcement anchor cable group is composed of at least three reinforcement anchor cables, and the three reinforcement anchor cables are respectively arranged in an upward, horizontal and downward shape in a group, forming a "fan" shape, the length of the upward reinforcement anchor cable is slightly longer than the horizontal reinforcement anchor cable, and the downward reinforcement anchor cable is longer than the upward reinforcement anchor cable; the length of the reinforcement anchor cable group penetrating into the rock mass is about half of the width of the recovery unit, and the length of the adjacent reinforcement anchor cable groups penetrating into the rock mass is different, and the bottom is opened in a "W" shape; the interval between the reinforcement anchor cable groups is one quarter of the width of the recovery unit; S5, the mining unit, first carries out bottom trenching to form a lower compensation space, then the ore is dropped downward from the lower stage rock drilling chamber (1) of the lower middle section, and then the ore is dropped downward from the upper stage rock drilling chamber (7) of the upper middle section to complete the mining; when dropping the ore, high and low position blasting technology is used to reduce the empty top span during the blasting process, forming an approximate pressure balance arch, and at the same time, high position blasting drilling is carried out along the side goaf of the mining face.

2. A safe and efficient mining method for high-stage large-scale stopes in underground metal mines according to claim 1, characterized in that The upward inclination angle of the reinforcement anchor cable group (3) is 30-45°, and the downward inclination angle is 45-55°.

3. A safe and efficient mining method for high-stage large-scale stopes in underground metal mines according to claim 1, characterized in that In the S4, three anchor cables are arranged in a fan shape, the lengths of adjacent reinforcement anchor cables penetrating into the rock mass are different, and the bottoms of the groups are staggered in a "W" shape. On the basis of the lateral reinforcement bodies with a flat mining surface, the ore-rock structural belt and large joint surfaces are effectively avoided.

4. A safe and efficient mining method for high-stage large-scale stopes in underground metal mines according to claim 1, characterized in that Add small radial guide tubes between the reinforcement anchor cable groups located in the lower middle part.

5. A safe and efficient mining method for high-stage large-scale stopes in underground metal mines according to any one of claims 1 to 4, characterized in that If the adjacent mining units do not have the conditions for constructing reinforcement anchor cables, the corresponding mining units shall adopt the normal mining height.

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