Combined filling mining method for micro-inclined thick and large ore body with broken top plate

Abstract

The invention discloses a combined filling mining method for a micro-inclined thick and large ore body with a broken top plate, and belongs to the technical field of underground mining. According to the method, a staged collaborative mining mode is adopted for solving the problem that safety and efficiency are difficult to consider in mining of micro-inclined thick and large ore bodies with broken roof surrounding rocks. In the first stage, in the whole area of the top of an ore body, an integral artificial roof firmly combined with surrounding rock is constructed through an access stoping process of mining one at intervals, three-dimensional connection of roof anchor rods and reinforcing meshes and a one-time high-strength filling process, and the roof caving risk is controlled fundamentally. And in the second stage, under the reliable protection of the artificial roof, efficient stoping is conducted on the lower ore body through a downward parallel deep hole stage open stoping subsequent filling method, and stope stability is guaranteed and cost is optimized through the sequence of stoping one at intervals and the differential filling strategy of one-step high strength and two-step low strength. According to the method, safe, efficient and low-depletion mining of the thick and large ore body under the condition of the broken roof is achieved.

Description

Technical Field

[0001] This invention relates to the field of underground mining technology, and more specifically, to a combined backfilling mining method for slightly inclined thick ore bodies with fractured roof surrounding rock. Background Technology

[0002] The safe and efficient mining of mineral resources has always been a core issue in the mining industry. For gently dipping ore bodies, the choice of mining technology is particularly unique and highly dependent on the stability of the overlying roof rock. Because the ore body is nearly horizontal, a large area of ​​the roof is exposed after the formation of the goaf, and its own stability directly determines the safety and economy of mining activities.

[0003] Currently, several relatively mature mining schemes have been developed in the industry for slightly dipping ore bodies of varying thicknesses. For thinner ore bodies, full-scale mining is often used due to its simple process and high efficiency. However, this method requires extremely stable roof rock to support large exposed goaf areas for extended periods without extensive support. For medium-thickness ore bodies, room-and-pillar mining is a more common choice. Regular or irregular pillars are reserved to support the roof, thus requiring slightly less roof stability than full-scale mining. However, this method still relies on the surrounding rock having considerable self-stabilizing capacity, and permanent pillars can cause some resource loss. When the mining target becomes a thick ore body, the stope-filling method is widely used to balance efficiency and a certain degree of safety redundancy. This method first efficiently extracts a large amount of ore in a stope, and then fills the goaf in one go to support the surrounding rock. Its successful implementation implies a key prerequisite: the ore and rock (especially the roof) must remain stable and not collapse during the interval between mining and filling. In addition, the upward horizontal layered filling method, as one of the safest methods, achieves immediate support for the roof and sides by mining one layer and filling one layer at a time. Theoretically, it can be applied to unstable surrounding rock conditions, but its problems of low mining efficiency, complex procedures and high costs are also very prominent.

[0004] It is evident that existing mainstream methods face severe challenges when dealing with thick, slightly dipping ore bodies with fractured surrounding rock. On the one hand, methods relying on the self-stabilizing surrounding rock, such as the full-area method, room-and-pillar method, and subsequent open-hole backfilling method, are highly susceptible to roof collapse accidents under fractured roof conditions, compromising safety. Furthermore, the mixing of fallen waste rock with the ore leads to a sharp increase in dilution rate, severely impacting economic efficiency. On the other hand, the only method capable of handling fractured surrounding rock conditions, the upward horizontal layered backfilling method, suffers from low production efficiency and excessively high costs, making it difficult to meet the economic requirements of large-scale, thick ore body mining. This core contradiction—the incompatibility between "safety" and "efficiency"—severely restricts the development and utilization of such complex and refractory mineral resources.

[0005] Although there have been attempts in the industry to improve the working environment by constructing artificial roofs, most solutions are either limited to inefficient route-based mining, failing to fundamentally solve the efficiency bottleneck; or they only focus on roof reconstruction, failing to deeply integrate with a complete and efficient mining system. Furthermore, there is a lack of systematic solutions regarding how to reliably combine artificial roofs with the original fractured roof, and how to ensure the safety of large-scale blasting operations under the artificial roof. Therefore, developing an integrated mining method that can synergistically solve the two major challenges of roof control and efficient mining, achieving a balance between safety and economy, has become a pressing technological bottleneck in the current mining engineering field. Summary of the Invention

[0006] The technical problem to be solved: This invention aims to overcome the shortcomings of existing technologies and provide a combined backfilling mining method for thick, slightly inclined ore bodies with fractured roofs. This method achieves efficient mining of thick ore bodies by combining phased and regional processes, while ensuring the safety and controllability of the roof.

[0007] To achieve the above objectives, the core of the technical solution adopted by this invention is as follows: First, a continuous and complete high-strength artificial false roof is constructed in the area immediately below the broken roof using a backfilling process; then, under the reliable protection of this artificial false roof, the lower main ore volume is mined using a high-efficiency downward parallel deep hole stage open space backfilling method.

[0008] Specifically, the present invention provides a method for combined backfilling mining of a slightly inclined, thick ore body with a fractured roof, characterized by comprising the following steps: S1. Artificial false roof construction stage: Below the ore-rock boundary of the roof, a continuous and integral artificial false roof is constructed at the top of the entire mining area using the inlet filling method; S2. High-efficiency mining stage of the lower ore body: After the construction of the integral artificial false roof is completed, the ore body below it is mined using the downward parallel deep hole stage open space subsequent filling method.

[0009] Specifically, in step S1, the construction of the integral artificial false roof includes: S11. At a predetermined location 3.4m-4.5m below the ore-rock boundary of the roof, multiple parallel mining routes are arranged along the dip of the ore body. S12. The mining route is mined in an alternating order. After each mining route is mined, the roof support anchor bolts are immediately installed to provide temporary support to the roof. S13. A crushed ore cushion layer is laid on the supported access road bottom slab, and a steel mesh is laid on the cushion layer; wherein, the steel mesh is connected to the roof support anchor rod through the suspension rod, and is anchored to the surrounding rock through the false roof anchor rod constructed on the access road side wall to form a three-dimensional stress structure; S14. Perform a one-time high-strength filling on the completed reinforcement path; S15. After all the mining routes and interconnecting roadways have been filled according to the procedures of S12-S14, the integral artificial false roof is formed.

[0010] Specifically, in step S13, the thickness of the crushed ore cushion layer is 200mm; 1-2 lifting rods are arranged along the width direction of the access road, and the spacing along the length direction of the access road is 2.0m-3.0m.

[0011] Specifically, in step S13, the steel mesh includes longitudinally arranged main bars and transversely arranged secondary bars, with the main bars and secondary bars intersecting and connected; the steel mesh of adjacent routes is lapped and connected by steel bars that are reserved at the ends or sides and folded up.

[0012] Specifically, in step S2, the subsequent backfilling method for the downward parallel deep hole stage mining includes: S21. Divide the lower ore body into mining areas along the strike, arrange the mining areas perpendicular to the strike, and further combine them into panels; S22. Within the panel area, the stope adjacent to the panel pillar is mined first as a one-step stope. After the one-step stope is mined, a high-strength backfill body is used for subsequent backfilling. S23. After the backfill material of the first-stage stope reaches the design strength, the adjacent stope is mined as the second-stage stope. After the second-stage stope is mined, a backfill material with a lower strength than that of the first-stage stope is used for subsequent backfilling.

[0013] Specifically, in steps S22 and S23, the mining of the first-step and second-step mining areas is carried out by drilling parallel deep holes downward in the rock-drilling chamber below the integral artificial false roof, and the ore is broken off by blasting in layers.

[0014] Specifically, the diameter of the parallel deep holes is 100m-165mm, the hole spacing is 3m×3m, and the layered blasting height is 3m-5m.

[0015] Specifically, in step S2, a "fishbone" shaped trench bottom structure is constructed at the bottom of the mining area for shoveling and transporting the collapsed ore.

[0016] Specifically, the filling slurry with a mortar-to-sand ratio of 1:4 is used in the first-step mining area, and the filling slurry with a mortar-to-sand ratio of 1:20 is used in the second-step mining area.

[0017] Specifically, the strength of the filling body of the integral artificial false roof is higher than the strength of the filling body in the first-step stope during the mining of the lower ore body.

[0018] Beneficial effects The beneficial effects of this invention are significant. First, the first-step backfilling process proactively and reliably addresses the problem of a fractured roof, constructing a permanent safety barrier and fundamentally eliminating the risk of roof collapse. Second, after securing a safe working platform, the second step employs a large-scale, high-efficiency open-stope backfilling method to recover the main ore volume, greatly improving overall mining efficiency and overcoming the inefficiency of single-layer backfilling methods. Finally, by optimizing the panel layout and employing a phased differential backfilling strategy, backfilling costs are effectively controlled while ensuring stope stability. This invention achieves a harmonious balance between safety and efficiency under the challenging condition of a fractured roof, providing an innovative solution for the safe and efficient mining of similar ore bodies. Attached Figure Description

[0019] Figure 1 This is a schematic diagram illustrating the operational principle of a combined backfilling mining method for a micro-inclined thick ore body with a fractured roof, according to the present invention. Figure 2 for Figure 1 Sectional view II-II in the middle; Figure 3 for Figure 1 Sectional view of section III-III; Figure 4 for Figure 1 Sectional view of section IV-IV; Figure 5 A schematic diagram of the AA surface construction for the base slab and hanging rods of the false ceiling; Figure 6 A schematic diagram of the BB surface construction for the base slab and hanging rods of the false ceiling; Figure 7 This is a schematic diagram of the C-plane construction of the base slab and suspension rods of the false ceiling.

[0020] Explanation of reference numerals in the attached figures: 1-Stage transport roadway; 2-Transport connecting roadway; 3-Ore extraction roadway; 4-Pass shaft; 5-Inclined ramp; 6-Roof transport connecting roadway; 7-Entry roadway connecting to backfilled stope; 8-Drilling chamber connecting roadway; 9-Drilling and roof cutting roadway; 10-Roof support anchor bolt; 11-False roof anchor bolt; 12-Ore extraction connecting roadway; 13-Cutting trench drilling roadway; 14-Retreat access roadway; 15-High-strength backfill; 16-Low-strength backfill; 17-Backfill retaining wall; 18-Roof return airway; 19-Roof return air connecting roadway; 20 21-Return air connecting roadway for drilling chamber; 22-Pantry pillar; 23-Mining body; 24-Bottoming space; 25-Collapsed ore; 26-Backfilling return air shaft; 27-Main reinforcement; 28-Secondary reinforcement; 29-Hanging reinforcement; 30-Bottoming crushing; 31-Cutting shaft; 32-Bottoming blast hole; 33-Mining blast hole; 34-Crossing transport roadway; 35-Cut roof connecting roadway; 36-Drilling chamber; 37-Ore body roof; 38-Ore body floor; 39-Roof ore-rock boundary; 40-Floor ore-rock boundary; a represents the dip direction of the ore body, b represents the strike direction of the ore body, and c represents the vertical direction of the ore body. Detailed Implementation

[0021] These embodiments are provided to make the disclosure thorough and complete, and to fully express the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, material composition, numerical expressions, and values ​​set forth in these embodiments should be interpreted as exemplary only and not as limiting.

[0022] This invention provides a combined backfilling mining method for a slightly inclined, thick ore body with a fractured roof, specifically comprising the following two steps: The first step is the construction of an artificial false roof. At a predetermined distance below the ore-rock boundary 39 of the ore body roof, a series of rectangular mining access roads 14 are arranged along the dip direction a of the ore body. Mining follows a skip-the-one-access sequence, i.e., skip-access mining. After blasting, each mining access road 14 immediately anchors the exposed roof. Then, a crushed ore cushion layer (i.e., bottom crushed ore 29) is laid on the bottom of the access road, and a steel mesh is laid on the cushion layer. The steel mesh is connected to the roof support anchors 10 of the roof via suspension bars 28, and simultaneously anchored to the surrounding rock via false roof anchors 11 on the sidewalls. Finally, the access road is filled with high-strength material in one go. After all mining access roads 14 and their connecting roadways have been filled according to this process, a well-integrated reinforced concrete structural layer is formed below the ore body roof 37, serving as a safe artificial false roof for subsequent mining.

[0023] The second step is the efficient mining of the lower ore body. After the artificial false roof is constructed, the thick ore body below it is mined using the downward parallel deep-hole staged open-pit subsequent backfilling method. The lower ore body is divided into stopes along the strike, arranged perpendicular to the strike, and further divided into panels. Within each panel, the ore body 22 to be mined is mined first in the stopes adjacent to the panel pillar 21, following the same alternating mining sequence. In a dedicated drilling chamber 36, parallel deep holes are drilled downwards to break the ore through layered blasting. The broken ore 24 is transported out through a pre-formed "fishbone" shaped ore extraction structure at the bottom. After one stope is mined, backfilling is carried out immediately; the first-stage stope is backfilled with high-strength backfill material, and the second-stage stope is backfilled with low-strength backfill material. The subsequent stopes can only be mined after the backfill material of the adjacent first-mined stope has reached the design strength.

[0024] The embodiments of this disclosure will be further described in detail below with reference to the accompanying drawings and examples. The detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of this disclosure by way of example, but should not be used to limit the scope of this disclosure. This disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0025] Example 1: Taking a certain underground metal mine as an example, the target ore body has an average thickness of 35m and a dip angle of approximately 12°. The roof of the hanging wall, directly above the ore body, consists of fractured rock layers influenced by tectonic structures, making it extremely unstable. (Reference) Figures 1 to 7 The mining process using the combined backfilling mining method of this invention involves the following specific steps: Specifically, the first stage: the construction of an integral artificial false roof.

[0026] The objective of this stage is to construct a continuous, complete, and firmly bonded high-strength reinforced concrete slab beneath the fractured direct orebody roof 37, serving as a permanent artificial pressure arch to provide absolutely safe roof conditions for the large-scale mining in the second stage.

[0027] The exemplary S11 preparatory work involves arranging preparatory roadways at an elevation approximately 4.0m below the hanging wall boundary (i.e., the ore body roof 37). First, in the surrounding rock on both sides of the ore body strike direction b, a roof haulage connecting roadway 6 and a roof return air roadway 18 extending along the dip are constructed. Then, within the roof haulage connecting roadway 6, several access roads 7 are excavated vertically to the ore body in the ore body direction c, at designed intervals (e.g., corresponding to the panel centerline and pillar centerline). These access roads 7 will serve as the starting point and haulage channels for subsequent access mining operations. Within the access roads 7, a series of parallel mining access roads 14 are constructed along the ore body dip (direction a). The access roadway cross-section is designed to be 4.0m wide and 4.0m high, with a length equal to half the width of the ore body strike. Depending on the degree of fracturing of the roof 37 of the ore body, this height can be adjusted between 3.4m and 4.5m. The more severe the fracturing, the smaller the height value should be, so as to facilitate roof support as soon as possible.

[0028] As an example, the S12 mining and temporary roof support: Mining operations are carried out in a "skip-one" sequence, i.e., skip-mining routes. First, the odd-numbered routes closest to the hanging wall boundary are mined. Each mining route 14 is mined forward using shallow-hole blasting. After each blast, before the workers have completely evacuated, temporary support must be immediately provided for the newly exposed fractured ore body roof 37. The support uses slotted pipe roof anchors 10, with a length of 2.0m, installed at a density of 5 anchors per row with a row spacing of 1.5m. Slotted pipe anchors are suitable for immediate support of fractured roofs due to their full-length anchoring and strong adaptability to surrounding rock deformation. This "mining as you go" process effectively controls the loosening and deformation of the roof in a short time, creating a safe working space for the subsequent construction of a permanent false roof.

[0029] As an example, the construction of the S13 artificial false floor: After the temporary support of the approach roof is completed, the construction of the artificial false floor (i.e., the base plate of the future artificial false roof) is carried out. First, the roadway floor is leveled, and a layer of crushed ore about 200mm thick is intentionally retained to form a bottom crushed ore cushion layer 29. The main function of this cushion layer is to absorb and attenuate the shock waves generated by the large-scale deep-hole blasting below during the subsequent second-stage mining, preventing the shock waves from directly acting on the artificial false roof filling body and causing it to crack or be damaged. The thickness of the crushed ore cushion layer is determined through blasting simulation tests; a thickness of 200mm can attenuate about 60% of the blasting shock stress wave.

[0030] Subsequently, a steel mesh framework was laid approximately 200mm above the 29th layer of crushed ore. This framework consisted of longitudinally arranged φ12mm main bars 26 (spaced 1.2m) and transversely arranged φ12mm secondary bars 27 (spaced 0.7m). Its innovative structure lies in: Preferably, the three-dimensional suspension system uses φ12mm suspension rods 28, the upper end of which is welded to the tail end of the installed top anchor rod 10, and the lower end is welded to the intersection of the main reinforcement 26 and secondary reinforcement 27 of the steel mesh. Two suspension rods are arranged along the width of the access road, and one row is arranged every 2.5m along the direction of access road advancement. This system connects the anchor rods anchored in the original roof slab with the artificial false bottom steel mesh into a whole, so that the two work together to bear the load.

[0031] Preferably, lateral anchoring: On both sides of the access road, at a height of 0.4m from the bottom plate, drill holes with a downward inclination of 5°-10° and a depth of 1.5m, install φ20mm false top anchor rods 11, and weld the exposed 0.3m section of the anchor rods to the main reinforcement 26 of the steel mesh, thereby anchoring the false top structure in the surrounding rock on both sides.

[0032] Preferably, the steel mesh of adjacent access routes is lapped and welded at the ends or sides by pre-reserved 0.5m long steel bars (27 secondary bars folded up at the ends and 26 main bars folded up on the sides) to ensure that the filling of all access routes does not form an isolated concrete block, but a continuous integral steel mesh, which is eventually poured into an integrated reinforced concrete slab.

[0033] As an example, high-strength filling and false roof formation for S14 and S15: After the steel mesh is laid, robust filling retaining walls 17 are constructed at both ends of the access road. High-strength cemented filling grout with a cement-sand ratio of 1:4 is used to fill the entire access road in one go through pipelines. The uniaxial compressive strength of the filling body after 28 days of curing is not less than 5MPa. After all odd-numbered access roads and their related connecting roadways have been filled and cured to the required standard according to this process, even-numbered access roads are mined and filled according to the same process. Finally, a high-strength artificial false roof with a thickness of about 4.0m, continuous internal steel reinforcement, firmly bonded to the broken roof through an "anchor bolt-suspender" system, and having an blast-resistant buffer layer is formed under the roof of the entire mining panel.

[0034] Specifically, the second stage: efficient mining of the lower ore body.

[0035] With the reliable protection of an integral artificial false roof, ore bodies with a lower thickness exceeding 30m can be mined using the high-efficiency, large-scale deep-hole open-field method.

[0036] The exemplary S21 stope layout divides the ore body below the artificial false roof into 18m wide stopes perpendicular to the strike. Every five stopes form a panel, with 18m wide panel pillars 21 between each panel. At the bottom of the stope, stage haulage roadways 1, cross-vein haulage roadways 34, and stope haulage connecting roadways 2 are arranged. A key innovation is the adoption of a highly efficient "fishbone-shaped" trench bottom structure: at the center of the stope bottom, through the ore body floor 38, an ore extraction connecting roadway 12 is excavated, with ore extraction roadways 3 symmetrically arranged on both sides at approximately 11m intervals, resembling a fishbone. This ensures that collapsed ore is evenly and thoroughly removed, greatly reducing bottom residue.

[0037] Demonstration S22 Drilling and Cracking: From the existing upper roadway system (such as roof transport connecting roadway 6), downward ramps 5 and drilling chamber connecting roadways 8 are excavated to the upper boundary of each stope, and the sides are widened to form a safe drilling chamber 36. Workers use down-the-hole drills to drill parallel deep holes (recovery blast holes 32) within the solid chambers. The hole diameter is 110mm, and the hole pattern parameters are 3.0m (row spacing) × 3.0m (hole spacing). Cracking is performed using a layered lateral caving method, with 3-4 rows of blast holes per blast, and a caving height of approximately 10-12m. Throughout the entire recovery process, a ore layer with a thickness of not less than 6m is maintained below the artificial false roof as a "protective cushion layer," effectively isolating the artificial false roof from the direct impact of blasting dynamic loads.

[0038] As an example, in S22, the ore extraction and subsequent differential backfilling occur as follows: the collapsed ore 24 falls into the bottom trench under its own weight, is scooped out from the extraction roadway 3 by an electric loader, and then transported away via the transportation system. The sequence of extraction and backfilling is crucial for ensuring the stability and economy of the stope.

[0039] As an example, S22 one-step mining (construction of artificial pillars): First, the two stopes immediately adjacent to the pillar 21 in each panel are mined (i.e., the one-step stopes). These stopes serve as lateral supports for subsequent mining, and their backfill must possess high strength. Therefore, after the one-step stopes are emptied, high-strength backfill slurry with a 1:4 lime-sand ratio is immediately used for subsequent backfilling, forming a high-strength backfill body 15. The strength of this backfill body after curing is comparable to that of an artificial false roof, thus functioning as a permanent artificial pillar.

[0040] As an example, the S23 two-step mining (efficient mining of main ore volume): Mining can only begin after the backfill material of the adjacent first-step stope reaches its design strength (e.g., 3.0 MPa). The second-step stope, surrounded by high-strength backfill materials on both sides and an artificial false roof above, exists in a relatively stable stress environment. Therefore, after the second-step stope is emptied, to save costs, low-strength backfill slurry with a 1:20 lime-sand ratio can be used for filling, forming a low-strength backfill body 16. Its main function is to fill the empty area and maintain ground pressure balance, with significantly reduced strength requirements (e.g., 0.5 MPa or higher is sufficient).

[0041] The beneficial effects of the present invention have been fully verified in this embodiment.

[0042] First, it has fundamentally improved safety. Through the construction of an integral artificial false roof that is integrated with the surrounding rock in the first phase, the fractured roof has been actively managed, transforming the uncontrollable natural roof into a reliable artificial structure, and achieving "inherent" control over roof safety.

[0043] Secondly, production efficiency has undergone a qualitative leap. In the second stage, more than 80% of the ore volume is mined using the downward parallel deep hole stage open field method, which has a production efficiency (mining intensity and ore output capacity) that is far higher than that of the traditional upward approach or layered filling method. The overall production capacity of the panel can be increased to 3-5 times that of the traditional method.

[0044] Subsequently, the economic benefits were significantly improved. The differential filling strategy of "high-intensity in the first step and low-intensity in the second step" greatly reduced filling costs while ensuring the stability of the mining area, making the technology economically feasible.

[0045] Finally, the resource recovery rate is high. The overall false top effectively isolates the waste rock in the hanging wall, and the optimized "fishbone" bottom structure reduces ore residue, so that the ore dilution rate and loss rate of this method can be effectively controlled within 10%.

[0046] Example 2: refer to Figures 1 to 5 This invention proposes a combined backfilling mining method for a slightly inclined, thick ore body with a fractured roof, which includes the following steps: S1. The access road and filling stope shall be arranged 3.4m-4.5m below the ore-rock boundary 39 of the roof. The mining access road 14 shall be arranged along the dip direction a of the ore body. The height of the mining access road 14 shall be 3.4m-4.5m and the width shall be 3-5m. The value shall be smaller for higher fracture degree and larger for lower fracture degree. The length of the mining access road 14 shall be half the length of the panel.

[0047] S11. Preparation. At a location 3.4-4.5m below the ore-rock boundary 39 of the ore body roof, at predetermined positions in the surrounding rock along the two directions of the ore body strike b, a roof haulage connecting roadway 6 and a roof return air roadway 18 are respectively arranged along the dip direction a of the ore body. Within the roof haulage connecting roadway 6, corresponding to the center line of the panel pillar 21 and the panel center line, a pass-through filling stope connecting roadway 7 and a roof return air connecting roadway 19 are excavated perpendicular to the ore body strike b to the roof return air roadway 18. At the position corresponding to the panel center line of the roof haulage connecting roadway 6, a pass 4 is excavated, with its lower part connected to the stage haulage roadway 1. Within the roof return air roadway 18, corresponding to the position of the panel pillar, a filling return air lift 25 is arranged, connecting to the lower stage haulage roadway 1, serving as the return air and safety passage for the subsequent filling stope in the lower stage open area. A return access roadway 14 is arranged along the ore body dip a within the pass-through filling stope connecting roadway 7 within the ore body.

[0048] S12. Mining. Each mining route 14 is mined by tunneling and blasting. After the ore is extracted, the roof is reinforced with roof support anchors 10, and then the bottom laying, reinforcement laying, and filling processes are carried out.

[0049] Furthermore, the top support anchor 10 adopts a slotted pipe anchor with a length of 2m. The spacing between support rows is 1-2m, with a smaller value for high roof breakage and a larger value for low breakage. There are 4-6 anchors per row.

[0050] Furthermore, the mining access road 14, which is close to the ore boundary 39 of the roof, is mined first, in an alternating mining sequence. After the mining of each mining access road 14 is completed, bottom filling is carried out, and the filling body is cured to meet the strength requirements.

[0051] S13. Bottom Laying. After each mining pass 14 is completed, manual leveling is carried out to smooth out the remaining ore on the bottom plate of the mining pass 14, making the bottom plate flat both longitudinally and laterally. A 200mm thick layer of bottom crushed ore 29 is left on the bottom plate. The bottom crushed ore 29 has a good absorption and weakening effect on the blasting shock wave, reducing the damage to the backfill body caused by drilling and blasting, and also preventing the backfill body from collapsing and causing ore dilution.

[0052] S14. Laying reinforcement. On the sidewall of the mining access road 14 at the boundary of the roof rock 39, at a height of 0.4m from the bottom plate, drill a downward inclined hole with a depth of 1.5m (5°~10°) every 1-1.5m to install the false roof anchor rod 11. The anchor rod is made of Ф20mm threaded steel, with 0.3m of the rod exposed. The exposed part of each anchor rod is connected to the main reinforcement 26 by welding. The length of the welded part is not less than 200mm to improve the overall strength of the artificial false roof.

[0053] Furthermore, a 20cm elevation is placed on the bottom crushed ore 29 for laying the bottom reinforcement mesh. The main reinforcement 26 of the bottom reinforcement mesh is φ12mm steel bar, with a spacing of 1-1.5m; the secondary reinforcement 27 is φ12mm, with a spacing of 0.5-0.8m; the main reinforcement 26 is at the bottom and the secondary reinforcement 27 is at the top. The intersection of the main reinforcement 26 and the secondary reinforcement 27 is reinforced by wrapping or welding with 16# iron wire. When the end or side of the mining access 14 is a mining access, the main reinforcement 26 or secondary reinforcement 27 at the end and side are left with an extra 0.5m for folding up. The secondary reinforcement 27 is folded up at the end of the access for the mining area, and the main reinforcement 26 is folded up on the side of the access for the mining area, for the overlapping of the bottom reinforcement mesh of adjacent mining areas.

[0054] Furthermore, the upper end of the suspension rod 28 is connected to the top anchor rod 10, and the lower end of the suspension rod 28 is connected to the junction of the main reinforcement 26 and the secondary reinforcement 27 of the bottom plate. One or two suspension rods 28 are arranged perpendicular to the direction of the road, and the spacing of the suspension rods along the direction of the road is 2.0-3.0m.

[0055] S15. Filling. After the paving and reinforcement work is completed, filler retaining walls 17 are erected at both ends of the access road. Then, the access road is filled in one go using a 1:4 lime-sand ratio filling material.

[0056] S16. After the mining access road 14 on both sides of the access road 7 is filled, the bottom, reinforcement and filling of the access road 7 are carried out. The process flow is the same as that of the mining access road 14.

[0057] S2. Below the entry and filling stope, the ore body is mined using the downward parallel deep-hole stage open-stope subsequent filling method. The stopes are arranged along the strike direction of the ore body, with a length equal to the width of the ore body. The stope width is 15-20m. Panels are set along the width of the stopes, with a length of 160-180m. Each panel contains 6-10 stopes, and the panel pillar width is 15-20m. An even number of stopes are arranged in each panel, which allows for the use of fewer high-strength filling bodies (15) in the panel pillars, saving filling costs.

[0058] S21. Preparation: From the centerline of each panel pillar 21 within the stage transport roadway 1, a cross-cut transport roadway 34 is excavated along the strike direction b of the ore body, connecting it to the stage transport roadway 1 on the other side. Within the surrounding rock on one side of the ore body strike direction b, a transport connecting roadway 2 for subsequent filling of the stope is excavated along the dip direction a. A ore extraction connecting roadway 12 is excavated perpendicularly between every two stops, connecting the stage transport roadway 1 and the stope transport connecting roadway 2 in the strike direction. At a distance of approximately 8-10m on both sides of the ore extraction connecting roadway 12, a trenching and drilling roadway 13 parallel to the ore extraction connecting roadway 12 is excavated for bottom drilling and receiving ore from stope collapses within each stope. Ore extraction roadways 3 are arranged every 10-12m within the ore extraction connecting roadway 12, ensuring even distribution within the stope and preventing ore residue formation. A ramp 5 is excavated within the stope transport connecting roadway 2 to connect with the top access filling stope connecting roadway 7. A downward-sloping drilling chamber connecting roadway 8 is excavated from the access filling stope connecting roadway 7, serving as a passage for subsequent drilling and ventilation in the filling stope. The drilling chamber connecting roadways 8, connecting various stops along the ore body dip, form the roof-cutting connecting roadway 35.

[0059] S22, Drilling and Cutting: Within the top-cutting connecting roadway 35, corresponding to the centerline position of each stope, the stope drilling top-cutting roadway 9 and the drilling chamber return air connecting roadway 20 are excavated. The drilling top-cutting roadway 9 is used as a free face to extend to the boundary of each stope to form the drilling chamber 36. Within the stope transport connecting roadway 2, corresponding to the boundary line of the two stops, the ore extraction connecting roadway 12 is excavated. Within the stope transport connecting roadway 2, corresponding to the predetermined position of each stope, the trench drilling roadway 13 parallel to the ore extraction connecting roadway 12 is excavated. Within the ore extraction connecting roadway 12, the ore extraction roadway 3 is excavated every 10-12m, forming a "fishbone" type trench ore extraction bottom structure with the ore extraction connecting roadway 12.

[0060] Furthermore, parallel deep holes with a diameter of 100-165mm are drilled downwards in the rock drilling chamber 36, with a hole spacing of 3m×3m.

[0061] Furthermore, a cutting well 30 is drilled upwards at a predetermined position within the trench drilling roadway 13. The well is 2m × 2m in size. Using the cutting well 30 as the free surface, 4-6 rows of cutting blast holes 33 are arranged around it, with a row spacing of 1.2-1.5m. Fan-shaped bottom-pulling blast holes 31 parallel to the cutting blast holes are drilled within the trench drilling roadway. A bottom-pulling cutting groove is formed by blasting simultaneously within the trench drilling roadway 13. Then, using the cutting groove as the free surface and compensation space, the bottom-pulling blast holes 31 are blasted 3-5 times to form a bottom-pulling space 23, providing compensation space and ore receiving space for large-scale ore collapse in the stope.

[0062] S23. Ore Recovery: Layered blasting is carried out in the downward parallel deep holes within the drilling chamber 36, with a layer height of 3-5m. The final remaining ore layer thickness is not less than two layer heights to ensure operational safety. Electric loaders are used to scoop ore from the ore connection roadway 12 below the bottom ore boundary 40 into the ore roadway 3, transporting it to the stage pass 4 or directly loading it into mining trucks for lifting to the surface. Within the panel, the adjacent stops of the panel pillar 21 are recovered first, with each stop being recovered on an alternate basis. Adjacent stops are recovered only after the filling body of the first-stage stope reaches the design strength.

[0063] S23. Backfilling: After the stope is mined out, the passage to the stope is blocked by the backfilling retaining wall 17. Then, the backfilling pipeline is used to transport the connecting roadway 6 from the roof to the cutting connecting roadway 35 to the corresponding stope for backfilling. When the stope backfill reaches the designed backfilling strength, the adjacent stope can be mined out.

[0064] Furthermore, the first-stage mining chamber uses a backfill with a 1:4 lime-sand ratio, while the second-stage mining chamber uses a backfill with a 1:20 lime-sand ratio.

[0065] The embodiments of this disclosure have now been described in detail. To avoid obscuring the concept of this disclosure, some details known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0066] It should be noted that, in the description of this disclosure, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationship, are only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0067] Furthermore, the terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. "Vertical" is not strictly vertical, but within the permissible margin of error. "Parallel" is not strictly parallel, but within the permissible margin of error. Terms such as "including" or "contains" mean that the element preceding the word encompasses the element listed after the word, and do not exclude the possibility of encompassing other elements as well.

[0068] It should also be noted that, in the description of this disclosure, unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this disclosure depending on the specific circumstances. When a particular device is described as being located between a first device and a second device, an intermediary device may or may not be present between the particular device and the first or second device.

[0069] All terms used in this disclosure have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as idealized or highly formalized, unless expressly defined herein.

[0070] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0071] While specific embodiments of this disclosure have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of this disclosure. Those skilled in the art should understand that modifications can be made to the above embodiments or equivalent substitutions can be made to some technical features without departing from the scope and spirit of this disclosure. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any manner.

Claims

1. A combined filling mining method for a top-fractured, slightly inclined and thick ore body, characterized in that, The method comprises the following sequential steps: S1, artificial false roof construction stage: a continuous integral artificial false roof is constructed on the top of the entire mining area below the ore body roof boundary by using the drift filling method; S2, high-efficiency mining of the lower ore body stage: after the construction of the integral artificial false roof is completed, the ore body below the integral artificial false roof is mined by using the downward parallel deep hole stage empty field subsequent filling method.

2. The combined filling mining method according to claim 1, characterized in that, In step S1, the construction of the integral artificial false roof specifically comprises: S11, a plurality of parallel mining drifts are arranged along the ore body inclination at a predetermined position 3.4m-4.5m below the ore body roof boundary; S12, the mining drifts are mined in turn according to the one-in-one-out sequence, and after each mining drift is mined, the roof is temporarily supported by constructing roof anchor rods; S13, a broken ore cushion is laid on the floor of the supported drift, and a steel mesh is laid on the cushion; wherein the steel mesh is connected with the roof anchor rods through hanging rods and anchored with the surrounding rock through the false roof anchor rods constructed on the side of the drift to form a three-dimensional force structure; S14, the drift with the laid steel mesh is filled once with high strength; S15, after all the mining drifts and the interconnected connecting roadways are filled according to the procedures S12-S14, the integral artificial false roof is formed.

3. The method of combined filling mining according to claim 2, characterized in that, In step S13, the thickness of the broken ore cushion is 200mm; the hanging rods are arranged in 1-2 along the width direction of the drift and spaced 2.0m-3.0m along the length direction of the drift.

4. The method of combined filling mining according to claim 2, characterized in that, In step S13, the steel mesh comprises longitudinally arranged main rods and transversely arranged auxiliary rods, and the main rods and the auxiliary rods are cross-connected; the steel meshes of adjacent drifts are connected by overlapping the steel rods reserved and folded at the ends or sides.

5. The method of combined filling mining according to claim 1, characterized in that, In step S2, the downward parallel deep hole stage empty field subsequent filling method mining specifically comprises: S21, the lower ore body is divided into stope fields along the strike, the stope fields are arranged vertically along the strike, and further combined into panels; S22, in the panel, first, the ore room adjacent to the panel pillar is mined as a one-step stope field, after the one-step stope field is mined, high-strength filling body is used for subsequent filling; S23, after the filling body of the one-step stope field reaches the designed strength, the ore room adjacent to the one-step stope field is mined as a two-step stope field, after the two-step stope field is mined, filling body with a strength lower than that of the one-step stope field is used for subsequent filling.

6. The method of combined filling mining according to claim 5, characterized in that, In steps S22 and S23, the mining of the one-step stope field and the two-step stope field is carried out in the rock drilling chamber below the integral artificial false roof, and parallel deep holes are drilled downward to collapse the ore in a layered blasting manner.

7. The method of combined filling mining according to claim 6, characterized in that, The parallel deep hole has a diameter of 100mm-165mm, a hole row spacing of 3m×3m, and a layered blasting height of 3m-5m.

8. The method of combined filling mining according to claim 5, characterized in that, In step S2, a "fishbone” type trench is constructed at the bottom of the stope field to serve as the bottom structure of the ore drawing for the collapsed ore.

9. The method of combined filling mining according to claim 5, characterized in that, The filling material slurry sand ratio used in the one-step stope field is 1:4, and the filling material slurry sand ratio used in the two-step stope field is 1:

20.

10. The combined filling mining method according to any of claims 1 - 9, characterized in that, The strength of the filling body of the integral artificial false roof is higher than that of the filling body of the one-step stope field in the mining of the lower ore body.

Images