The combined support mining method of segmented open pit method for unstable ore body in the upper wall

Abstract

The present application provides a combined support mining method for the segmented open-pit method of an unstable ore body in the upper plate, which belongs to the field of mining engineering, wherein the middle section of the ore body is divided into plate areas along the strike and pillars are set, the plate area is divided into the upper plate area and the lower plate area, and the lower plate is divided into three sections; the mining area is divided along the strike in the upper plate area, and the mining area is divided perpendicular to the strike in the lower plate area; pedestrian skylights, layered connecting roads, cutting bottom tunnels and related return air facilities are constructed; the upper plate area is mined layer by layer and supported simultaneously; the lower plate area uses the empty area formed in the upper plate as compensation space for downward mining; finally, the empty area is sealed or filled with waste rock. The present application divides the ore body into upper and lower plate areas, combines shallow hole grooving with the upper plate support process, not only realizing layered mining and blasting grooving in the upper plate area, but also providing blasting compensation space for mining in the lower plate area, reducing loss and depletion, and providing working conditions for the reinforcement and support of unstable rock bodies in the upper plate.

Description

Technical Field

[0001] The present invention relates to the technical field of mining engineering, and in particular to a segmented open-pit method combined with support mining method for an unstable upper plate ore body. Background Art

[0002] Currently, the sublevel open-stop mining method is often used for thick, steeply inclined ore bodies with stable ore bodies but unstable hanging walls. To improve hanging wall stability and mining safety, this method primarily involves reserving a certain thickness of retaining wall in the hanging wall or reinforcing the rock mass with long anchor cables grouting from the upper sublevel support chamber into the hanging wall of the sublevel. While this method improves the stability of the stope's hanging wall, it significantly increases the mining loss rate, especially when rich ore zones exist in the hanging wall, making the overall applicability of this method poor. While reinforcing the rock mass with long anchor cables grouting from the upper sublevel support chamber into the hanging wall of the sublevel can quickly reinforce and reconstruct the rock mass and improve the stability of the hanging wall, it also presents challenges such as large support engineering workload, high construction costs, and poor support system integrity and bearing capacity.

[0003] In view of this, it is necessary to design an improved segmented open-pit mining method combined with support mining for unstable upper wall ore bodies to solve the above problems. Summary of the Invention

[0004] In view of the technical problems existing in the background technology, the present application provides a segmented open-field combined support mining method for unstable ore bodies in the upper plate, aiming to solve the technical problems of poor mining stability, large mining losses and high support costs of unstable ore bodies in the upper plate.

[0005] The present application provides a method for mining an unstable ore body in the upper wall by a segmented open-pit method and a combined support method, comprising the following steps:

[0006] S1. Divide the middle section into panels along the strike of the ore body, with pillars between panels; divide the panel into an upper panel and a lower panel, with the upper panel serving as the trough support area and the lower panel serving as the forward row mining area; divide the lower panel into three sections along the height of the middle section; divide the upper panel into stopes along the strike of the ore body; and divide the lower panel into stopes perpendicular to the strike of the ore body;

[0007] S2. Construct pedestrian shafts along the ore body inclination in the inter-panel columns, and construct layered connecting roads every 5m in the vertical direction toward the upper panel stope. Construct a cutting bottom roadway along the strike of the upper panel stope at the middle level, and construct a return air shaft, return air connecting roadway, and connecting shaft upwards.

[0008] S3. The upper wall area is mined layer by layer from bottom to top, and double reinforcement and grouting anchor support operations are carried out synchronously after each layer is mined;

[0009] S4. Using the empty area formed in the upper wall area as the compensation space for the forward mining of the lower wall area, the lower wall area is segmented and mined downward;

[0010] S5. After mining is completed, the empty area shall be sealed or filled with waste rock.

[0011] As a further improvement of the present application, in step S3, the mining method of the upper wall area is:

[0012] S31. Using the cut bottom roadway as the free surface, top mining is carried out on the upper layer;

[0013] S32. Use a scraper to shovel out the ore, with each ore discharge amounting to one-third of the layered ore, and the remaining ore serving as a platform for further mining;

[0014] S33. After the mine is completed, support operations are carried out, including floor leveling, drilling and point construction, anchor installation and grouting, double reinforcement and anchor tray installation;

[0015] S34. After the support is completed, the upper layer is continued to be mined and supported with the layered space as the blasting free surface and working space until the mining and support of the entire upper plate area are completed, and the upper plate area is mined to form a cutting groove in the lower plate area.

[0016] As a further improvement of the present application, in the described top pressure mining, the diameter of the blasthole is 35~45mm, the hole depth is 2.5~3.0m, the blasthole inclination is 30~45°, the minimum resistance line is 0.8~1.0m, the row spacing is 1.0~1.5m, and the height of each ore drop is 1.5~2.0m.

[0017] As a further improvement of the present application, the floor of the stratified stope is leveled to form a working space with a height of ≥2.5m; after leveling, wooden pillars or anchor nets are used to temporarily support the local safety hazard areas.

[0018] As a further improvement of the present application, the drilling and placement construction method is: constructing anchor holes toward the upper plate area, the anchor holes are perpendicular to the layered rock wall, the hole diameter is 60~70mm, the hole depth is 8.0~9.0m, and the hole row spacing is 2.0~2.5m.

[0019] As a further improvement of the present application, the anchor cable is a hollow grouting anchor cable with a diameter of 25-35 mm, a length of 8.0-10.0 m, and a breaking strength ≥1600 MPa.

[0020] As a further improvement of the present application, grouting is carried out by mixing ordinary Portland cement with medium-grained sand, with a cement-sand ratio of 1:(1~1.5) and a water-cement ratio of 0.4~0.45.

[0021] As a further improvement of the present application, the distances between the longitudinal ribs and the transverse ribs of the double ribs are equal, and the anchor cable tray is installed close to the double ribs and the rock wall.

[0022] As a further improvement of the present application, in step S4, the mining method of the lower plate area is:

[0023] S41. Construction of upward fan-shaped medium-long holes within the rock tunnel. Blasting operations are carried out using inter-row micro-difference blasting, with a micro-difference time of 50-75ms. Detonation is initiated from the bottom of the hole in reverse. During ore collapse, retreat mining is conducted using the upper wall void as the free face. Within each section, mining is first conducted in the mining room stope, followed by the mining pillar stope. Mining is completed within the same section before moving to the next section, until mining is complete in the entire lower wall stope.

[0024] S42. Fresh air flows through the sub-section rock drilling tunnel or the middle section rock drilling tunnel into the stope void, diluting the blasting smoke. The polluted air then flows through the return air connecting tunnel, connecting skylight, or the upper sub-section rock drilling tunnel into the upper-middle section connecting road, and then flows through the upper-middle section main transport tunnel into the main return air duct.

[0025] S42. Use remote-controlled scrapers to carry out mining operations, transfer the collapsed ore to the segmented chute at the entrance of the segmented rock drilling tunnel or in the empty area, and then release it into the mid-section mine car and transport it to the surface ore bin through the main hoisting system.

[0026] As a further improvement of the present application, the diameter of the fan-shaped medium-deep hole is 60~65mm, the hole depth is 5.0~18.0m, the row spacing is 1.4~1.5m, the hole bottom distance is 1.8~2.0m, and the side hole angle is 15~20°.

[0027] The beneficial effects of this application are:

[0028] The present application provides a combined support mining method for the segmented open-pit method of an unstable ore body in the upper plate, which divides the middle section of the ore body into plate areas along the strike and sets pillars, and divides the plate areas into the upper plate trough support area and the lower plate forward mining area, with the lower plate divided into three sections; the upper plate area is divided into mining areas along the strike, and the lower plate area is divided into mining areas perpendicular to the strike; pedestrian skylights and layered connecting roads are constructed in the pillars, and cutting and pulling bottom tunnels and related return air facilities are constructed along the strike of the upper plate area; the upper plate area is mined layer by layer and double reinforcement and grouting anchor cable support are carried out simultaneously; the lower plate area uses the empty area formed in the upper plate as compensation space for downward mining; and finally, the empty area is sealed or filled with waste rock. The present application divides the ore body into upper and lower plate areas, combines shallow hole troughing with the upper plate support process, and not only realizes the layered mining and blasting troughing of the ore body in the upper plate area, but also provides blasting compensation space for the forward mining of the lower plate stope, reduces loss and depletion, and provides working conditions for the reinforcement and support of the unstable rock mass in the upper plate.

[0029] This application combines grouting anchor cables with double reinforcement support, which not only enhances the integrity and bearing capacity of the support system, expands the support area, and improves the stability of the surrounding rock, but also can adjust the stiffness of the support system to a certain extent to adapt to the uneven deformation of the upper plate surrounding rock.

[0030] This application provides a new safe, reliable and economical method for supporting the upper wall of unstable segmented open-pit mining area. The equipment used in this method is conventional rock drilling equipment, which has simple process, low cost and broad application prospects, and provides a guiding basis for mine mining production and safety management.

[0031] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] To more clearly illustrate the technical solution of this application, the following is a brief introduction to the drawings used in this application. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0033] Figure 1 This is a vertical cross-sectional view of the middle section of the stope of the unstable ore body in the upper wall in the embodiment of this application;

[0034] Figure 2 This is a horizontal cross-section of the middle section of the stope of the unstable hanging wall ore body in the embodiment of this application;

[0035] Figure 3 This is a longitudinal cross-section of the upper wall area of ​​the unstable ore body in the embodiment of this application;

[0036] Figure 4 This is a design diagram of double ribs in the embodiment of this application;

[0037] Explanation of the accompanying symbols: 1. Middle section main transport tunnel; 2. Middle section connecting road; 3. Middle section rock drilling tunnel; 4. Remaining ore; 5. Unstable rock mass in the upper plate; 6. Stable rock mass in the upper plate; 7. Grouting anchor cable; 8. Layered stope; 9. Return air shaft; 10. Goaf in the upper middle section; 11. Upper middle section connecting road; 12. Upper middle section main transport tunnel; 13. Connecting shaft; 14. Stope top pillar; 15. Return air connecting tunnel; 16. Ore body; 17. Medium and deep hole blasting hole; 18. Segmented horizontal tunnel; 19. Segmented connecting road; 20. Segmented rock drilling tunnel; 21. Chute connecting road; 22. Ore chute; 23. Inter-plate column; 24. Pedestrian shaft; 25. Layered connecting road; 26. Shaft connecting road; 27. Anchor cable tray; 28. Double reinforcement; 2801. Longitudinal reinforcement; 2802. Transverse reinforcement. DETAILED DESCRIPTION

[0038] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0040] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0041] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0042] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0043] For the segmented open-stop mining of inclined to steeply inclined thick ore bodies, existing technologies improve stability by reserving retaining wall mines in the upper wall or constructing long anchor grouting to reinforce the rock mass. However, these methods may increase the mining loss rate, especially when there is a rich ore zone in the upper wall, or face problems such as large support engineering volume, high cost and insufficient support system performance.

[0044] In order to solve the technical problems of poor mining stability, large mining losses and high support costs in the unstable upper plate ore body, the present application provides a segmented open-pit method combined with support mining method for the unstable upper plate ore body, wherein, by dividing the ore body into the upper and lower plate areas, the shallow hole grooving is combined with the upper plate support process, which not only realizes the layered mining and blasting grooving of the ore body in the upper plate area, but also provides blasting compensation space for the positive row mining of the lower plate mining area, reduces loss and depletion, and provides working conditions for the reinforcement and support of the unstable rock mass in the upper plate.

[0045] Please refer to Figures 1 to 4 The present invention provides a method for mining an unstable ore body in an upper wall by a segmented open-pit method and a combined support method, comprising the following steps:

[0046] S1. Divide the middle section into panels along the strike of the ore body, with pillars placed between panels. Divide the panels into upper and lower panels, with the upper panel serving as the trough support area and the lower panel serving as the forward row mining area. Divide the lower panel into three subsections along the height of the middle section. The upper panel is divided into stopes along the strike of the ore body; the lower panel is divided into stopes perpendicular to the strike of the ore body.

[0047] S2. Construct pedestrian shafts 24 along the orebody's inclination within the panel column 23. Construct layered connecting roads 25 at 5-meter intervals toward the upper panel stope. Construct a cutting bottom roadway at the mid-section level along the upper panel stope's strike. Construct upwards return air shaft 9, return air connecting roadway 15, and connecting shaft 13.

[0048] S3. The upper plate area is mined layer by layer from bottom to top, and double reinforcement 28 and grouting anchor cable 7 support operations are carried out synchronously after each layer is mined;

[0049] S4. Use the voids formed in the upper wall area as compensation space for forward mining in the lower wall area, and conduct downward mining in the lower wall area;

[0050] S5. After mining is completed, the empty area shall be sealed or filled with waste rock.

[0051] In the technical solution of the embodiment of the present application, the combined support of double ribs 28 and grouting anchor cables 7 effectively improves the stability of the upper wall rock mass, reduces rock deformation and displacement, ensures the safety of mining operations, optimizes the upper wall support method, reduces unnecessary wall ore reservation, and reduces mining loss rate and improves resource utilization, especially when there are rich ore zones. Compared with the traditional long anchor cable grouting reinforcement method, the combined support of double ribs 28 and grouting anchor cables 7 reduces the amount of support engineering, reduces construction costs, and improves economic benefits. By using downward mining and utilizing the empty area formed in the upper wall area as compensation space, the mining efficiency of the lower wall area is improved.

[0052] Furthermore, in some embodiments, in step S3, the mining method of the upper wall area is:

[0053] S31. Using the cut bottom roadway as the free surface, top mining is carried out on the upper layer;

[0054] S32. Use a scraper to shovel out the ore, with each ore discharge amounting to one-third of the layered ore, and the remaining ore serving as a platform for further mining;

[0055] S33 after the completion of the mine support operations, support operations include floor leveling, drilling point construction, anchor installation and grouting, double reinforcement 28 and anchor tray 27 installation;

[0056] S34. After the support is completed, the upper layer is continued to be mined and supported with the layered space as the blasting free surface and working space until the mining and support of the entire upper plate area are completed, and the upper plate area is mined to form a cutting groove in the lower plate area.

[0057] In the technical solution of the embodiment of the present application, efficient layered mining is achieved by using the top-pressing mining method with the cut bottom tunnel as the free surface, which speeds up the mining progress of the entire upper plate area. The use of scrapers to shovel out the ore in batches not only improves the ore-out efficiency, but also provides convenience for subsequent mining by retaining part of the ore as a working platform. Support operations are carried out after the ore is out to ensure the stability of the working surface and reduce the risk of safety accidents. After the support is completed, the mining and support of the upper layers are continued to realize the cyclic operation of mining and support, which improves the continuity and efficiency of the operation. By placing ore in the upper plate area mining field, a cutting groove is formed in the lower plate area mining field, which provides the necessary compensation space and free surface for the downward mining of the lower plate area, further improving the overall mining efficiency.

[0058] Furthermore, in some embodiments, in roof pressure mining, the diameter of the blasthole is 35~45 mm, the hole depth is 2.5~3.0 m, the blasthole inclination is 30~45°, the minimum resistance line is 0.8~1.0 m, the row spacing is 1.0~1.5 m, and the height of each ore drop is 1.5~2.0 m.

[0059] In the technical solution of the embodiment of the present application, by setting appropriate blasthole diameter, hole depth, inclination, minimum resistance line and row spacing, the efficiency and effect of the blasting operation can be ensured, and effective crushing of the ore can be achieved. Appropriate blasthole parameters help to achieve uniform ore crushing, reduce the generation of large ore pieces, and improve the efficiency of subsequent mining and transportation. Accurate blasthole arrangement and ore drop height control help to reduce ore loss and depletion and improve resource utilization. Reasonable blasthole inclination and minimum resistance line design can reduce the impact of blasting on the surrounding rock mass and reduce the safety risks brought by blasting.

[0060] Furthermore, in some embodiments, the floor of the stratified stope 8 is leveled to form a working space with a height of ≥2.5 m; after leveling, wooden pillars or anchor nets are used to temporarily support the local safety hazard areas.

[0061] In the technical solution of the embodiments of this application, leveling operations can eliminate floor unevenness and potential hazards, reducing safety accidents during operations. Temporary support measures can promptly control rock displacement in locally unstable areas, specifically addressing areas of potential safety hazards, creating better conditions for subsequent support operations, and avoiding over-supporting the entire stope, thereby saving support materials and construction costs.

[0062] Furthermore, in some embodiments, the drilling and placement construction method is: constructing anchor holes in the upward direction of the plate area, the anchor holes are perpendicular to the layered rock wall, the hole diameter is 60~70mm, the hole depth is 8.0~9.0m, and the hole row spacing is 2.0~2.5m.

[0063] In the technical solution of the embodiments of this application, the anchor holes are arranged perpendicular to the layered rock wall, ensuring that the anchor cables are effectively anchored in the stable rock strata, thereby providing stronger support and improving the overall stability of the hanging wall area. The specified hole diameter, hole depth, and hole row spacing help achieve uniform anchor cable distribution, avoid support blind spots, and ensure uniform support effects. The regular arrangement of anchor cable holes facilitates subsequent operations such as anchor cable installation, grouting, and tray installation, ensuring the smooth progress of support operations.

[0064] Furthermore, in some embodiments, the anchor cable is a hollow grouting anchor cable with a diameter of 25-35 mm, a length of 8.0-10.0 m, and a breaking strength ≥1600 MPa.

[0065] In the technical solution of the embodiments of this application, the anchor cable has a diameter of 25-35 mm, which provides a strong load-bearing capacity and can adapt to the support requirements of different rock mass conditions. The appropriate length ensures that the anchor cable penetrates deeply into the stable rock formation, thereby providing more effective anchoring and enhancing the stability of the hanging wall rock mass. The high breaking strength of the anchor cable can withstand greater tensile forces, ensuring that the anchor cable will not break when the rock mass moves or deforms, thereby maintaining the stability of the support system.

[0066] Furthermore, in some embodiments, the grouting is performed by mixing ordinary Portland cement with medium-grained sand, with a cement-sand ratio of 1:(1-1.5) and a water-cement ratio of 0.4-0.45.

[0067] In the technical solution of the embodiment of the present application, the hollow grouting anchor cable can fill the gap between the anchor cable and the hole wall by grouting to form a stronger anchor body, improve the bonding force between the anchor cable and the rock mass, and enhance the support effect. The grouting operation can improve the crack and pore structure of the rock mass, improve the integrity and shear strength of the rock mass. After solidification, the mixed slurry can evenly transfer stress, reduce stress concentration between the anchor cable and the rock mass, and improve the overall support effect. The appropriate water-cement ratio ensures that the slurry has good fluidity, allowing the slurry to penetrate into the small cracks of the rock mass and enhance the integrity of the rock mass. Ordinary Portland cement has high early strength and can harden quickly, thereby providing support as soon as possible. The optimized configuration of the ash-sand ratio and the water-cement ratio can make the grouting body have a higher final strength to meet the needs of long-term support.

[0068] Furthermore, in some embodiments, the longitudinal ribs 2801 and the transverse ribs 2802 of the double ribs 28 are spaced at equal distances, and the anchor tray 27 is installed close to the double ribs 28 and the rock wall.

[0069] In the technical solution of the present embodiment, the equal spacing between longitudinal ribs 2801 and transverse ribs 2802 ensures that the double ribs 28 provide uniform support throughout the structure, helping to disperse pressure from the rock wall and reduce localized stress concentration. The anchor cable tray 27, acting as a transition layer between the anchor cable and the rock wall, disperses the tension of the anchor cable, reducing direct impact on the rock wall and improving the anchoring effect.

[0070] Furthermore, in some embodiments, in step S4, the mining method of the footwall area is:

[0071] S41. Construction of upward fan-shaped medium-long holes within the rock tunnel. Blasting operations are carried out using inter-row micro-difference blasting, with a micro-difference time of 50-75ms. Detonation is initiated from the bottom of the hole in reverse. During ore collapse, retreat mining is conducted using the upper wall void as the free face. Within each section, mining is first conducted in the mining room stope, followed by the mining pillar stope. Mining is completed within the same section before moving to the next section, until mining is complete in the entire lower wall stope.

[0072] S42. Fresh air flows through the sub-section rock drilling tunnel 20 or the middle section rock drilling tunnel 3 into the stope void, diluting the blasting smoke. The polluted air then flows through the return air connecting tunnel 15, the connecting skylight 13, or the upper sub-section rock drilling tunnel into the upper middle section connecting tunnel 11, and then through the upper middle section main transport tunnel 12 into the main return air duct.

[0073] S42. Use a remote-controlled scraper to carry out mining operations, and transfer the collapsed ore to the segmented chute at the entrance of the segmented rock drilling tunnel 20 or in the empty area. Then, the ore is slid into the middle mine car and transported to the surface ore bin through the main hoisting system.

[0074] In the technical solution of the embodiment of the present application, through upward fan-shaped medium-deep hole micro-difference blasting, backward mining, airflow control and remote-controlled scraper ore extraction, the blasting and mining efficiency are significantly improved, the operation safety is ensured, the ventilation and ore transportation processes are optimized, the cost is reduced, and efficient and safe mining operations are achieved.

[0075] Furthermore, in some embodiments, the diameter of the fan-shaped medium-long hole is 60~65mm, the hole depth is 5.0~18.0m, the row spacing is 1.4~1.5m, the hole bottom distance is 1.8~2.0m, and the side hole angle is 15~20°.

[0076] In the technical solution of the embodiment of the present application, more accurate and efficient blasting operations are achieved by precisely controlling the relevant parameters of the blasthole, which not only improves the ore recovery rate, but also enhances the stability of the working surface, further improving the safety and economic benefits of mining operations.

[0077] Some specific examples are listed below. It should be noted that the examples described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used without manufacturer's indication are all commercially available conventional products.

[0078] Example 1

[0079] This embodiment provides a method for mining an unstable hanging wall orebody using the sublevel open-stop method with combined support. The orebody to be mined is a tectonic alteration lithologic gold deposit at a certain mine. The primary mining body, orebody No. 1, exhibits a wide vein or large lens shape, with an S-shaped plan view and a gentle undulating distribution along the dip within the tectonic alteration zone. The orebody is approximately 2,300 meters long from north to south, with an overall strike of 12° and an overall dip of 282°. The dip is steeper in the north and tapers southward, with a maximum dip of nearly 75°, a minimum dip of 40°, and an average dip of 56°. The orebody has a maximum thickness of 40.59m, a minimum thickness of 12.45m, and an average thickness of 23.60m. The orebody is moderately stable to stable, consisting of an unstable hanging wall rock body 5 and a stable hanging wall rock body 6. The contact zone is particularly unstable, while the footwall rock body is moderately stable. The gold grade of the ore is low, with an average grade of approximately 1.84g / t. The metallic minerals in the ore are primarily pyrite, with occasional galena, sphalerite, and chalcopyrite. The non-metallic minerals in the ore are primarily quartz and sericite, followed by potassium feldspar, plagioclase, calcite, and trace amounts of fluorite and titanite. The hydrogeology and engineering geology in the area are simple, and the geological environment quality of the mining area is good. Furthermore, surface caving is permitted.

[0080] In combination with the mining technology conditions and production status, the design adopts the sub-level open-pit mining method, YGZ-90 guide rail rock drill for rock drilling, and remote control scraper for ore removal. Figures 1 to 4 As shown, the specific steps include:

[0081] S1. Stope division and structural parameters

[0082] Within the middle section, the ore body is divided into panels along the strike of the ore body. Each panel is 50m long, 50m high, and the same width as the ore body thickness. 15m-high pillars are placed between panels. Considering the mining safety risks posed by the unstable rock mass 5 in the upper wall, the panel is divided into an upper and lower wall. The upper wall serves as a trough support area, with stopes divided along the strike. The stopes are 50m long, 2.5-3.0m wide, and the same height as the middle section. The lower wall serves as a forward mining area, also serving as an egress channel for stratified mining in the upper wall. Stopes are divided perpendicular to the strike, with a span of 12.5m. The middle section is divided into three sections along the height, each 15m high. A stope top pillar 14 is placed adjacent to the upper-middle section goaf 10 in the panel. The thickness of this top pillar 14 is 8-12m, and no bottom pillars are retained.

[0083] S2. Layout of mining and cutting projects

[0084] The project primarily includes a pedestrian skylight 24, a return air skylight 9, a middle main transport tunnel 1, a middle connecting road 2, a middle drilling tunnel 3, a sub-level drilling tunnel 20, a sub-level connecting road 19, a sub-level drift 18, a chute connecting road 21, a mine chute 22, and a skylight connecting road 26. A pedestrian skylight 24, measuring 1.5m x 1.5m, was constructed along the ore body's inclination within the inter-panel column 23 to serve as a passage for pedestrians, materials, and equipment transport within the stope. Layered connecting roads 25 were constructed every 5.0m in elevation toward the upper wall stope, connecting the layered stopes 8. A cutting bottom tunnel was constructed horizontally in the middle section, along the direction of the upper wall stope, to provide a free surface and compensation space for layered mining. A return air skylight 9, a return air connecting tunnel 15, and a connecting skylight 13 were constructed upward from the cutting bottom tunnel and near the middle drilling tunnel 3 to serve as return air channels for the stope, also serving as a secondary safety exit.

[0085] S3. Layered mining and stope support in the hanging wall area

[0086] The mining sequence of the upper plate area is similar to the shallow hole ore retention method, and the mining is carried out layer by layer from bottom to top.

[0087] Taking the cutting bottom tunnel as the free surface, the upper layers are gradually pressed down and mined. The YT-28 air-leg rock drill is used for rock drilling. The blasthole specification is 40mm, the hole depth is 2.5~3.0m, the blasthole inclination is 30~45°, the minimum resistance line is 0.8~1.0m, the inter-row spacing is 1.0~1.5m, and 2# rock emulsion explosives are used for blasting. The height of the ore drop is 1.5~2.0m at a time.

[0088] After stratum mining is complete, a scraper is used to shovel out ore at the end of the middle drilling tunnel 3 or the sub-drilling tunnel 20. The ore output per shovel is one-third of the stratum drop volume, and the remaining ore 4 serves as a platform for further mining. When the mined stratum is higher than the sub-drilling tunnel 20, the ore is simultaneously transferred to the previous sub-drilling tunnel 20.

[0089] Now that all ore has been mined in stratified stope 8, stratified support work has begun. The specific process includes stratified floor leveling, drilling and placement, anchor cable installation and grouting, and installation of double reinforcement bars 28 and anchor cable trays 27.

[0090] The bottom plate of the layered stope 8 should be as flat as possible, and the height of the working space after leveling should be above 2.5m. For local areas with potential safety hazards, they should be thoroughly checked in a timely manner and temporary wooden pillars or anchor nets should be used for support.

[0091] Afterwards, the drilling rig is fixed at the layered setting position, and the YGZ-90 drilling rig is used to construct anchor holes in the upward direction. The blast holes should be perpendicular to the layered rock wall, with a hole diameter of 65mm, a hole depth of 8.0~9.0m, and a hole row spacing of 2.0~2.5m. The specific spacing can be flexibly adjusted according to the ore and rock conditions.

[0092] After all layered blastholes are completed, anchor cable installation and grouting begin. Grouting anchor cable 7 uses a 29mm nominal diameter hollow grouting anchor cable, 8.0-10.0m in length, and a breaking strength of 1670MPa. Ordinary Portland cement is used, and medium-grained sand is preferred. The cement-sand ratio is 1:1.25, and the water-cement ratio is 0.4-0.45. Grouting is performed in a single pass, and grouting ceases once slurry flows from the orifice.

[0093] Finally, install the double reinforcement bars 28 and anchor cable tray 27. Double reinforcement bars 28 are welded from 18mm diameter threaded steel bars, totaling 6.0m in length. Transverse reinforcement bars are welded every 2.0-2.5m along the length, with 10cm spacing between longitudinal reinforcement bars 2801 and transverse reinforcement bars 2802. Anchor cable tray 27 is constructed from Q235 steel plates, measuring 300mm x 300mm and 18mm thick. It should be installed close to the double reinforcement bars 28 and the rock face.

[0094] When the support of this layer is completed, the upper layer will continue to be mined and supported with the layer space as the free surface and working space, and then enter the next cycle until the mining and support of the entire upper plate mining area is completed. Finally, a large amount of ore will be released into the upper plate mining area to form a cutting groove for the lower plate mining area.

[0095] S4. Mining technology in the lower plate area

[0096] The footwall section adopts a descending mining method between sections, first mining the ore body 16 of the previous section, and then mining the next section. Within the section, the mining room stope is first mined, then the mining pillar stope is mined, and the mining of the next section is not started until all the mining of the same section is completed.

[0097] Rock Drilling and Blasting: A YGZ-90 rail-type rock drill was used to drill upward fan-shaped medium-deep holes in the rock tunnel. The diameter of the medium-deep blastholes (17) was 65 mm, the hole depth was 5.0-18.0 m, the row spacing was 1.4-1.5 m, the hole bottom distance was 1.8-2.0 m, and the side hole angle was 15-20°. A BQF-100 charge loader was used for continuous charging. The explosive used was rock powder emulsion explosive with a charge density of 1.05-1.15 g / cm 3 The hole mouth is plugged with taphole mud, with a plugging length of 1.0-1.5m. Inter-row micro-delay blasting is used, with a micro-delay time of 50-75ms, and digital electronic detonators are used for reverse detonation at the bottom of the hole. In case of ore collapse, retreat mining is carried out, using the upper wall void as the free face.

[0098] Mine ventilation: Fresh air flows into the mine void from the segmented rock drilling tunnel 20 or the middle rock drilling tunnel 3. After diluting the blasting smoke, the dirty air flows into the upper middle section connecting road 11 from the return air connecting tunnel 15, the connecting skylight 13 or the upper segmented rock drilling tunnel, and then flows into the main return air channel through the upper middle section main transport tunnel 12.

[0099] Mining out of the stope: 2.0m 3The remote-controlled scraper carries out the mining operation, and transfers the collapsed ore to the segmented chute at the entrance of the segmented rock drilling tunnel 20 or in the empty area, and then chutes it into the middle section mine car, and finally transports it to the surface ore bin through the main hoisting system.

[0100] S5. Empty area processing

[0101] After the empty area is mined, the drilling tunnel in the empty area will be sealed, and the safety of the mining area roof will be mainly maintained by pillars. If necessary, the empty area can be filled with waste rock.

[0102] The present application divides the disk area ore body into a trough support area and a forward mining area, arranges a shallow hole ore-retaining method stope along the ore body direction in the trough support area, and performs layered ore drop mining on the upper plate ore body. During the mining process, the layered advancement direction is flexibly adjusted according to the changes in the ore-rock boundary. During the mining process of the upper plate area, the support construction of double reinforcement bars 28 and grouting anchor cables 7 is carried out simultaneously. During the mining process, a small amount of collapsed ore is released from the nearest segmented rock drilling tunnel 20 and transported to the disk area segmented chute by a scraper. The present application improves mining efficiency and economic benefits, while reducing costs, and realizes the effective utilization of resources and environmental protection.

[0103] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for mining an unstable ore body with a segmented open pit method and a combined support method, characterized in that: The following steps are involved: S1. Divide the middle section into panels along the strike of the ore body, with pillars between panels; divide the panel into an upper panel and a lower panel, with the upper panel serving as the trough support area and the lower panel serving as the forward row mining area; divide the lower panel into three sections along the height of the middle section; divide the upper panel into stopes along the strike of the ore body; and divide the lower panel into stopes perpendicular to the strike of the ore body; S2. Construct pedestrian shafts along the ore body inclination in the inter-panel columns, and construct layered connecting roads every 5m in the vertical direction toward the upper panel stope. Construct a cutting bottom roadway along the strike of the upper panel stope at the middle level, and construct a return air shaft, return air connecting roadway, and connecting shaft upwards. S3. The upper wall area is mined layer by layer from bottom to top, and double reinforcement and grouting anchor cable support operations are carried out simultaneously after each layer is mined; the longitudinal and transverse reinforcements of the double reinforcements are equally spaced, and the anchor cable trays are installed closely against the double reinforcements and the rock wall; specifically: S31. Using the cut bottom roadway as the free surface, top mining is carried out on the upper layer; S32. After stratum mining is completed, ore is shoveled out of the middle tunnel or the end of the sub-drilling tunnel using a scraper. The ore output per shovel is one-third of the stratum's total ore output, with the remaining ore serving as a platform for further mining. When the mined stratum is higher than the sub-drilling tunnel, the ore is simultaneously transferred to the previous sub-drilling tunnel. S33. After the mine is completed, support operations are carried out, including floor leveling, drilling and point construction, anchor installation and grouting, double reinforcement and anchor tray installation; S34. After support is completed, continue top mining and support of the upper layer, using the layered space as the blasting free surface and working space, until the entire upper wall stope is mined and supported. Then, ore is drawn from the upper wall stope to form a cutting groove for the lower wall stope. S4. Using the empty area formed in the upper wall area as the compensation space for the forward mining of the lower wall area, the lower wall area is segmented and mined downward; within the segment, the mining room stope is first returned, and the mining pillar stope is returned; specifically: S41. Construction of upward fan-shaped medium-long holes within the rock tunnel. Blasting operations are carried out using inter-row micro-difference blasting, with a micro-difference time of 50-75ms. Detonation is initiated from the bottom of the hole in reverse. During ore collapse, retreat mining is conducted using the upper wall void as the free face. Within each section, mining is first conducted in the mining room stope, followed by the mining pillar stope. Mining is completed within the same section before moving to the next section, until mining is complete in the entire lower wall stope. S42. Fresh air flows through the sub-section rock drilling tunnel or the middle section rock drilling tunnel into the stope void, diluting the blasting smoke. The polluted air then flows through the return air connecting tunnel, connecting skylight, or the upper sub-section rock drilling tunnel into the upper-middle section connecting road, and then flows through the upper-middle section main transport tunnel into the main return air duct. S43. Utilizing remote-controlled scrapers for ore removal, the caving ore is transferred from the entry or empty area of ​​the sub-drilling tunnel to the sub-section chute. The ore is then released into the intermediate mine car and transported to the surface ore bin via the main hoist system. S5. After mining is completed, the empty area shall be sealed or filled with waste rock.

2. The method for mining an unstable ore body in the upper wall by means of a segmented open pit method and a combined support method according to claim 1, characterized in that: In the roof pressure mining, the diameter of the blasthole is 35~45mm, the hole depth is 2.5~3.0m, the blasthole inclination is 30~45°, the minimum resistance line is 0.8~1.0m, the row spacing is 1.0~1.5m, and the height of each ore drop is 1.5~2.0m.

3. The method for mining an unstable ore body in the upper wall by means of a segmented open pit method and a combined support method according to claim 1, characterized in that: The floor of the stratified mining area is leveled to form a working space with a height of ≥2.5m; after leveling, wooden pillars or anchor nets are used for temporary support of local safety hazard areas.

4. The method for mining an unstable ore body in the upper wall by means of a segmented open pit method and a combined support method according to claim 1, wherein: The drilling and placement construction method is: construct anchor holes towards the upper wall area, the anchor holes are perpendicular to the layered rock wall, the hole diameter is 60~70mm, the hole depth is 8.0~9.0m, and the hole row spacing is 2.0~2.5m.

5. The method for mining an unstable ore body in the upper wall by means of a segmented open pit method and a combined support method according to claim 4, characterized in that: The anchor cable is a hollow grouting anchor cable with a diameter of 25~35mm, a length of 8.0~10.0m, and a breaking strength of ≥1600MPa.

6. The method for mining an unstable ore body in the upper wall by means of a segmented open pit method and a combined support method according to claim 4, characterized in that: The grouting is done by mixing ordinary Portland cement with medium-grained sand, with a cement-sand ratio of 1:(1~1.5) and a water-cement ratio of 0.4~0.

45.

7. The method for mining an unstable ore body in the upper wall by means of a segmented open pit method and a combined support method according to claim 1, characterized in that: The diameter of the fan-shaped medium-long hole is 60-65 mm, the hole depth is 5.0-18.0 m, the row spacing is 1.4-1.5 m, the hole bottom distance is 1.8-2.0 m, and the side hole angle is 15-20 degrees.

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