Segmented open-stope combined support mining method for ore body with unstable hanging wall

Abstract

The invention provides a segmented open-stope combined support mining method for an ore body with an unstable hanging wall, and belongs to the field of mine engineering.The method comprises the steps that the middle section of the ore body is divided into panels in the strike direction, studs are arranged, the panels are divided into an upper panel and a lower panel, and the lower panel is divided into three segments; stopes are divided in the upper panel along the trend, and stopes are divided in the lower panel along the vertical trend; constructing a pedestrian courtyard, a layered connection way, a cutting undercut roadway and related air return facilities; stoping the hanging panel layer by layer and synchronously supporting; a dead zone formed by the hanging wall is used as a compensation space in the lower wall area, and descending type recovery is carried out; and finally, the goaf is subjected to blocking or barren rock filling treatment. According to the method, the ore body is divided into the upper panel area and the lower panel area, shallow hole groove broaching and the hanging wall supporting technology are combined, layered stoping and blasting groove broaching of the hanging wall area are achieved, meanwhile, a blasting compensation space is provided for stoping of the footwall area, loss and dilution are reduced, and operation conditions are provided for reinforcing and supporting of unstable hanging wall rock mass.

Description

Technical Field

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

[0002] At present, the segmented open-pit mining method is often used for inclined or steeply inclined thick ore bodies with stable ore bodies and unstable upper plates. In order to improve the stability of the upper plate and the safety of mining, a certain thickness of retaining wall ore is reserved in the upper plate or long anchor cable grouting is constructed to reinforce the rock mass through the upper segment support chamber to the upper plate of the current segment. Although the stability of the upper plate of the mining site is improved after the retaining wall is reserved, the mining loss rate is greatly increased, especially when there is a rich ore zone in the upper plate, the loss is more serious, and the overall applicability of the scheme is poor; and the long anchor cable grouting is constructed to reinforce the rock mass in the upper plate of the current segment through the upper segment support chamber. Although it can reinforce and reconstruct the rock mass in a short time and improve the stability of the upper plate rock mass, it also has problems such as large support engineering volume, high construction cost, poor integrity and bearing capacity of the support system.

[0003] In view of this, it is necessary to design an improved segmented open-pit method combined with support mining method for unstable upper plate ore body 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 an unstable upper plate ore body, aiming to solve the technical problems of poor mining stability, large mining losses and high support costs of an unstable upper plate ore body.

[0005] The present application provides a combined support mining method for segmented open pit method of an unstable ore body in the upper plate, comprising the following steps: S1. Divide the middle section into panels along the ore body strike, and set columns between panels; divide the panel into an upper panel and a lower panel, wherein the upper panel is a groove support area, and the lower panel is a positive row mining area; divide the lower panel into three sections along the height direction of the middle section; divide the upper panel into stopes along the ore body strike; and divide the lower panel into stopes perpendicular to the ore body strike; S2. Construct pedestrian skylights along the ore body inclination in the inter-panel columns, and construct layered connecting roads every 5m in height to the upper pan area stope; construct cutting bottom tunnels along the direction of the upper pan area stope at the middle level, and construct return air skylights, return air connecting roadways and connecting skylights upwards; S3. The upper plate 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; S4. Using the empty area formed in the upper plate area as the compensation space for the positive row mining of the lower plate area, the lower plate area is segmented for downward mining; S5. After mining is completed, the empty area shall be sealed or filled with waste rock.

[0006] As a further improvement of the present application, in step S3, the mining method of the upper plate area is: S31. Use the cut bottom tunnel as the free surface to carry out top mining on the upper layer; S32. Use a scraper to shovel out the ore, with the ore output each time being one-third of the ore output in each layer, and the remaining ore is used as a platform for further mining; S33. After the mine is completed, support operations are carried out, including floor leveling, drilling and point construction, anchor cable installation and grouting, double reinforcement and anchor cable tray installation; 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 is completed, and ore is placed in the upper plate area to form a cutting groove in the lower plate area.

[0007] 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.

[0008] As a further improvement of the present application, the floor of the stratified mining area is leveled to form a working space with a height of ≥2.5m; after the leveling, wooden pillars or anchor nets are used for temporary support of local safety hazard areas.

[0009] 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.

[0010] 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 of ≥1600 MPa.

[0011] 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.

[0012] As a further improvement of the present application, the spacing between the longitudinal ribs and the transverse ribs of the double ribs is equal, and the anchor cable tray is installed closely against the double ribs and the rock wall.

[0013] As a further improvement of the present application, in step S4, the mining method of the lower plate area is: S41. Construct upward fan-shaped medium-deep holes in the rock drilling tunnel, use inter-row micro-difference blasting to carry out blasting operations, with a micro-difference time of 50-75ms, and the detonation method is reverse detonation at the bottom of the hole. When the ore collapses, use the upper plate empty area as the free face for retreat mining. First, go back to the mining room stope in the section, then go back to the mining pillar stope. After all the mining in the same section is completed, go to the next section for mining, until the mining of the entire lower plate area is completed; S42. Fresh air flows into the empty area of ​​the stope through the segmented rock drilling tunnel or the middle segmented rock drilling tunnel, and after diluting the blasting smoke, the dirty air flows into the upper middle segment connecting road through the return air connecting tunnel, connecting skylight or the upper segmented rock drilling tunnel, and then merges into the main return air channel through the upper middle segment main transport tunnel; S42. Use remote-controlled shovel loaders to carry out mining operations. At the entrance of the segmented rock drilling tunnel or in the empty area, the collapsed ore is transferred to the segmented chute, and then released into the middle-stage mine car and transported to the surface ore bin through the main hoisting system.

[0014] As a further improvement of the present application, the blasthole 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°.

[0015] The beneficial effects of this application are: The present application provides a combined support mining method for the segmented empty field method of the 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, divides the plate areas into the groove support area of ​​the upper plate and the positive row mining area of ​​the lower plate, and divides the lower plate into three sections; divides the mining field along the strike in the upper plate area, and divides the mining field vertically in the lower plate area; constructs pedestrian skylights and layered connecting roads in the pillars, and constructs cutting and pulling bottom tunnels and related return air facilities 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 by the upper plate as compensation space for downward mining; and finally the empty area is blocked or filled with waste rock. The present application divides the ore body into upper and lower plate areas, combines shallow hole groove pulling with the upper plate support process, not only realizing the layered mining and blasting groove pulling of the ore body in the upper plate area, but also providing blasting compensation space for the positive row mining of the lower plate mining field, reducing loss and depletion, and providing working conditions for the reinforcement and support of the unstable rock mass in the upper plate.

[0016] By combining grouting anchor cables with double reinforcement support, the present application 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.

[0017] The present application provides a new safe, reliable and economical method for supporting the upper plate 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 mining production and safety management.

[0018] 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

[0019] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 A vertical cross-section of the middle section of the upper unstable ore body in the embodiment of the present application; Figure 2 It is a horizontal cross-section of the middle section of the upper unstable ore body in the embodiment of the present application; Figure 3 This is a longitudinal section of the upper plate area of ​​the unstable ore body in the embodiment of this application; Figure 4 This is a double rib design diagram in the embodiment of this application; Explanation of the reference numerals in the accompanying drawings: 1. Main transport tunnel in the middle section; 2. Connecting road in the middle section; 3. Rock drilling tunnel in the middle section; 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 mining area; 9. Return air shaft; 10. Goaf in the upper middle section; 11. Connecting road in the upper middle section; 12. Main transport tunnel in the upper middle section; 13. Connecting shaft; 14. Top pillar in the mining area; 15. Return air shaft; 16. Ore body; 17. Medium and deep hole blast holes; 18. Segmented horizontal tunnel; 19. Segmented connecting road; 20. Segmented rock drilling tunnel; 21. Chute connecting road; 22. Mine chute; 23. Inter-plate column; 24. Pedestrian shaft; 25. Layered connecting road; 26. Shaft connecting road; 27. Anchor cable tray; 28. Double reinforcement bars; 2801. Longitudinal reinforcement; 2802. Transverse reinforcement. DETAILED DESCRIPTION

[0021] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field 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" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0023] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0024] 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. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which 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 referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0025] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0026] For the segmented open-stop mining of inclined to steeply inclined thick ore bodies, the existing technology improves stability by reserving 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 the problems of large support engineering volume, high cost and insufficient support system performance.

[0027] In order to solve the technical problems of poor mining stability, large mining losses and high support costs of unstable ore bodies in the upper plate, the present application provides a segmented open-pit method combined with support mining method for unstable ore bodies in the upper plate, wherein the ore body is divided into upper and lower plate areas and 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 in the lower plate mining area, reduces losses and depletion, and provides working conditions for the reinforcement and support of the unstable rock mass in the upper plate.

[0028] Please refer to Figures 1 to 4 The present application provides a method for mining an unstable ore body in an upper plate by a segmented open pit method and a combined support method, comprising the following steps: S1. Divide the middle section into panels along the ore body strike, and set up pillars between panels; divide the panel into upper panel and lower panel, the upper panel is the trough support area, the lower panel is the positive row mining area, and the lower panel is divided into three sections along the height direction of the middle section; divide the upper panel into stopes along the ore body strike; divide the lower panel into stopes perpendicular to the ore body strike; S2. A pedestrian skylight 24 is constructed along the ore body inclination in the inter-panel column 23, and a layered connecting road 25 is constructed every 5m in the height direction toward the upper pan area stope; a cutting bottom tunnel is constructed along the direction of the upper pan area stope at the middle level, and a return air skylight 9, a return air connecting roadway 15 and a connecting skylight 13 are constructed upward; 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; S4. Using the empty area formed in the upper plate area as the compensation space for the positive row mining in the lower plate area, the lower plate area is mined in sections in a downward direction; S5. After mining is completed, the empty area shall be sealed or filled with waste rock.

[0029] In the technical solution of the embodiment of the present application, the combined support of the double ribs 28 and the grouting anchor cable 7 effectively improves the stability of the upper plate rock mass, reduces the deformation and displacement of the rock mass, ensures the safety of the mining operation, optimizes the upper plate support method, reduces unnecessary wall ore reservation, and especially reduces the mining loss rate and improves resource utilization when there is a rich ore belt. Compared with the traditional long anchor cable grouting reinforcement method, the combined support of the double ribs 28 and the grouting anchor cable 7 reduces the amount of support engineering, reduces construction costs, and improves economic benefits. Through downward mining and using the empty area formed in the upper plate area as compensation space, the mining efficiency of the lower plate area is improved.

[0030] Further, in some embodiments, in step S3, the mining method of the upper plate area is: S31. Use the cut bottom tunnel as the free surface to carry out top mining on the upper layer; S32. Use a scraper to shovel out the ore, with the ore output each time being one-third of the ore output in each layer, and the remaining ore is used as a platform for further mining; S33. After the mine is completed, support operations are carried out, including floor leveling, drilling and point construction, anchor installation and grouting, double reinforcement 28 and anchor tray 27 installation; 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 is completed, and ore is placed in the upper plate area to form a cutting groove in the lower plate area.

[0031] In the technical solution of the embodiment of the present application, by using the top-pressing mining method with the cut bottom tunnel as the free surface, efficient layered mining is achieved, which speeds up the mining progress of the entire upper plate area. The use of a scraper 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. After the ore is out, support operations are carried out to ensure the stability of the working surface and reduce the risk of safety accidents. After the support is completed, the upper layered mining and support are continued to achieve a 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.

[0032] Furthermore, in some embodiments, in 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.

[0033] 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 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 caused by blasting.

[0034] 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 potential safety hazard areas.

[0035] In the technical solution of the embodiment of the present application, the unevenness of the bottom plate and potential hidden dangers can be eliminated through the leveling operation, and the safety accidents during the operation can be reduced. Through temporary support measures, the rock displacement in the local unstable area can be controlled in time, and the safety hazard area can be dealt with in a targeted manner, creating better conditions for subsequent support operations, avoiding excessive support of the entire mining site, thereby saving support materials and construction costs.

[0036] Further, in some embodiments, the drilling and point construction method is: constructing anchor holes in the direction of 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.

[0037] In the technical solution of the embodiment of the present application, the anchor cable holes are arranged vertically to the layered rock wall, which can ensure that the anchor cable is effectively anchored in the stable rock layer, thereby providing stronger support force and improving the overall stability of the upper plate area. The specified hole diameter, hole depth and hole row spacing help to achieve uniform anchor cable distribution, avoid support blind spots, and ensure the uniformity of 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.

[0038] 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 of ≥1600 MPa.

[0039] In the technical solution of the embodiment of the present application, the diameter of the anchor cable is 25-35 mm, which has a strong bearing capacity and can adapt to the support requirements under different rock mass conditions. The appropriate length can ensure that the anchor cable penetrates into the stable rock layer, thereby providing a more effective anchoring effect and enhancing the stability of the upper rock mass. The anchor cable with high breaking strength can withstand greater tension, ensuring that the anchor cable will not break when the rock mass is displaced or deformed, thereby maintaining the stability of the support system.

[0040] 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.

[0041] 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 more solid anchor body, thereby improving the bonding force between the anchor cable and the rock mass and enhancing 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 a 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.

[0042] 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 cable tray 27 is installed close to the double ribs 28 and the rock wall.

[0043] In the technical solution of the embodiment of the present application, the equal spacing between the longitudinal ribs 2801 and the transverse ribs 2802 can ensure that the double ribs 28 provide uniform support in the entire structure, which helps to disperse the pressure of the rock wall and reduce local stress concentration. The anchor cable tray 27 serves as a transition layer between the anchor cable and the rock wall, which can disperse the tension of the anchor cable, reduce the direct impact on the rock wall, and improve the anchoring effect.

[0044] Further, in some embodiments, in step S4, the mining method of the lower plate area is: S41. Construct upward fan-shaped medium-deep holes in the rock drilling tunnel, use inter-row micro-difference blasting to carry out blasting operations, with a micro-difference time of 50-75ms, and the detonation method is reverse detonation at the bottom of the hole. When the ore collapses, use the upper plate empty area as the free face for retreat mining. First, go back to the mining room stope in the section, then go back to the mining pillar stope. After all the mining in the same section is completed, go to the next section for mining, until the mining of the entire lower plate area is completed; S42. Fresh air flows into the empty area of ​​the stope through the segmented rock drilling tunnel 20 or the middle segmented rock drilling tunnel 3, and after diluting the blasting smoke, the dirty air flows into the upper middle segmented connecting road 11 through the return air connecting road 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 segment main transport tunnel 12; S42. Use a remote-controlled scraper to carry out mining operations, transfer the collapsed ore to the segmented chute at the entrance of the segmented rock drilling tunnel 20 or in the empty area, and then release it into the middle section mine car and transport it to the surface ore bin through the main hoisting system.

[0045] 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 shovel loader mining, the blasting and mining efficiency are significantly improved, the operation safety is ensured, the ventilation and ore transportation process is optimized, the cost is reduced, and efficient and safe mining operations are achieved.

[0046] Furthermore, in some embodiments, 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°.

[0047] 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 recovery rate of the ore, but also enhances the stability of the working surface, further improving the safety and economic benefits of mining operations.

[0048] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be obtained commercially.

[0049] Example 1 This embodiment provides a method for mining an unstable ore body in the upper plate by a segmented open-field method and a joint support mining method. The ore body to be mined is a tectonic altered lithological gold deposit in a certain mine. The main mining No. Ⅰ ore body is in the shape of a wide vein or a large lens, with an "S" shape on the plane, and is distributed in the tectonic alteration zone in a gentle wave along the dip. The ore body is about 2,300 meters long from north to south, with an overall strike of 12° and an overall dip of 282°. The dip is steep in the north and becomes gentle to the south. The maximum dip is nearly 75°, the minimum dip is 40°, and the average dip is 56°. The maximum thickness of the ore body is 40.59m, the minimum thickness is 12.45m, and the average thickness is 23.60m. The ore body is a medium-stable to stable ore body, including an unstable rock body 5 in the upper plate and a stable rock body 6 in the upper plate, especially the unstable contact zone, and the rock body in the lower plate is moderately stable. The gold grade of the ore is not high, with an average grade of about 1.84g / t. The metal minerals in the ore are mainly pyrite, with occasional galena, sphalerite and chalcopyrite. The non-metallic minerals in the ore are mainly 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 types, the geological environment quality of the mining area is good, and the surface allows collapse.

[0050] Combined with the mining technology conditions and production status, the design adopts the segmented open-pit mining method, YGZ-90 rail-type rock drill for rock drilling, and remote-controlled scraper for mining. Figures 1 to 4As shown, the specific steps include: S1. Stope division and structural parameters The middle section is divided into panels along the strike of the ore body. The panel length is 50m, the height is 50m of the middle section, the width is the thickness of the ore body, and 15m columns are left between the panels. Considering the potential safety hazards of mining in the unstable rock mass 5 of the upper plate, the panel area is divided into the upper plate area and the lower plate area. The upper plate area is the trough support area, and the stopes are divided along the strike. The stopes are 50m long, 2.5~3.0m wide, and the height is the height of the middle section. The lower plate area is the positive row mining area, which also serves as the mining channel for the stratified mining of the upper plate area. The stopes are divided vertically, and the span of the stopes is 12.5m. The middle section is divided into three sections in the height direction, and the height of each section is 15m. The panel area is set with a stope top column 14 adjacent to the upper middle section goaf 10. The thickness of the stope top column 14 is 8~12m, and no bottom column is left.

[0051] S2. Layout of mining and cutting works It mainly includes pedestrian skylight 24, return air skylight 9, middle section main transport tunnel 1, middle section connecting road 2, middle section rock drilling tunnel 3, segmented rock drilling tunnel 20, segmented connecting road 19, segmented horizontal tunnel 18, chute connecting road 21, mine chute 22, skylight connecting road 26 and other projects. A pedestrian skylight 24 with a specification of 1.5m×1.5m is constructed along the ore body in the plate interval column 23, as a passage for pedestrians, materials and equipment transportation in the mining area. A layered connecting road 25 is constructed every 5.0m in the height direction toward the upper plate mining area, which is used to connect the layered mining area 8; a cutting bottom tunnel is constructed in the middle section along the direction of the upper plate mining area 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 are constructed upward from the cutting bottom tunnel and the position of the middle section rock drilling tunnel 3 as the return air passage of the mining area, and also serve as the second safe exit of the mining area.

[0052] S3. Layered mining and stope support in the upper wall area The mining sequence of the upper plate area is similar to the shallow hole ore retention method, which adopts the method of mining layer by layer from bottom to top.

[0053] Taking the cutting bottom tunnel as the free surface, the upper layers are gradually mined by top pressure. 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 explosive is used for blasting. The height of the ore falling at one time is 1.5~2.0m.

[0054] After the stratified mining is completed, the ore is shoveled out by a scraper at the end of the middle drilling tunnel 3 or the segmented drilling tunnel 20. The ore output each time is one-third of the stratified ore output, and the ore 4 is retained as a platform for continued mining. When the mining stratum is higher than the segmented drilling tunnel 20, the ore is synchronously transferred to the previous segmented drilling tunnel 20.

[0055] At present, all the ore in the stratified stope 8 has been mined out and the stratified support work has begun. The specific process includes stratified floor leveling, drilling and point construction, anchor cable installation and grouting, double reinforcement bar 28 and anchor cable tray installation 27 and other processes.

[0056] The bottom plate of the layered mining area 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.

[0057] Afterwards, fix the drilling rig at the layered setting position, and use the YGZ-90 drilling rig 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, which can be flexibly adjusted according to the ore and rock conditions.

[0058] After all the layered blastholes are constructed, the anchor cable installation and grouting are started. The grouting anchor cable 7 uses a hollow grouting anchor cable with a nominal diameter of 29mm, a length of 8.0~10.0m, and a breaking strength of 1670MPa. Ordinary silicate cement is used, and medium-grained sand is preferably used. The cement-sand ratio is 1:1.25, and the water-cement ratio is 0.4~0.45. The grouting method is used once, and the grouting is stopped when the slurry flows out of the hole.

[0059] Finally, the double ribs 28 and the anchor cable tray 27 are installed. The double ribs 28 are welded with 18mm diameter threaded steel bars, with a total length of 6.0m. They are welded and fixed by transverse ribs every 2.0~2.5m in the length direction. The spacing between the longitudinal ribs 2801 and the transverse ribs 2802 is 10cm. The anchor cable tray 27 is made of Q235 steel plate, with a specification of 300mm×300mm and a thickness of 18mm. The anchor cable tray 27 should be installed close to the double ribs 28 and the rock wall.

[0060] When the support of this layer is completed, the upper layer is continued to be mined and supported with the layer space as the free surface and working space, and the next cycle is entered until the mining and support of the entire upper plate mining area is completed. Finally, a large amount of ore is released into the upper plate mining area to form a cutting groove for the lower plate mining area.

[0061] S4. Mining technology in the lower plate area The lower plate area adopts downward mining between the 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, and then the mining pillar stope is mined. After all the mining in the same section is completed, the next section will be mined.

[0062] Rock drilling and blasting: YGZ-90 rail-type rock drill is used to construct upward fan-shaped medium-deep holes in the rock drilling tunnel. The diameter of the medium-deep hole 17 is 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°. BQF-100 type charge device is used for continuous charging. The explosive is rock powder emulsion explosive with a charge density of 1.05~1.15g / cm 3 The hole mouth is blocked with gun mud, and the blocking length is 1.0~1.5m. The row-to-row micro-difference blasting method is adopted, and the micro-difference time is 50~75ms. The digital electronic detonator is reversely detonated at the bottom of the hole. When the mine collapses, the upper plate empty area is used as the free face for retreat mining.

[0063] Ventilation of the mining area: fresh air flows into the mining area 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 merges into the main return air channel through the upper middle section main transport tunnel 12.

[0064] Mining site: 2.0m 3 The remote-controlled scraper is used to carry out mining operations, and the collapsed ore is transferred to the segmented chute at the entrance of the segmented rock drilling tunnel 20 or in the empty area, and then slid into the middle-stage mine car, and finally transported to the surface ore bin through the main hoisting system.

[0065] S5. Empty area processing 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.

[0066] The present application divides the pan area ore body into a groove support area and a positive row mining area, arranges a shallow hole ore retention method mining area along the ore body direction in the groove 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 double reinforcement 28 and the grouting anchor cable 7 support construction are 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 pan 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.

[0067] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A combined support mining method for unstable ore bodies in the upper plate, characterized in that: The following steps are involved: S1. Divide the middle section into panels along the ore body strike, and set columns between panels; divide the panel into an upper panel and a lower panel, wherein the upper panel is a groove support area, and the lower panel is a positive row mining area; divide the lower panel into three sections along the height direction of the middle section; divide the upper panel into stopes along the ore body strike; and divide the lower panel into stopes perpendicular to the ore body strike; S2. Construct pedestrian skylights along the ore body inclination in the inter-panel columns, and construct layered connecting roads every 5m in height to the upper pan area stope; construct cutting bottom tunnels along the direction of the upper pan area stope at the middle level, and construct return air skylights, return air connecting roadways and connecting skylights upwards; S3. The upper plate 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; S4. Using the empty area formed in the upper plate area as the compensation space for the positive row mining of the lower plate area, the lower plate area is segmented for downward mining; 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 plate by segmented open pit method and combined support according to claim 1 is characterized in that: In step S3, the mining method of the upper plate area is: S31. Use the cut bottom tunnel as the free surface to carry out top mining on the upper layer; S32. Use a scraper to shovel out the ore, with the amount of ore discharged each time being one-third of the amount of ore dropped in layers, and the remaining ore is used as a platform for further mining; S33. After the mine is completed, support operations are carried out, including floor leveling, drilling and point construction, anchor cable installation and grouting, double reinforcement and anchor cable tray installation; 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 is completed, and ore is placed in the upper plate area to form a cutting groove in the lower plate area.

3. The method for mining an unstable ore body in a segmented open pit method with combined support according to claim 2 is 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.

4. The method for mining an unstable ore body in a segmented open pit method with combined support according to claim 2 is 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.

5. The method for mining an unstable ore body in a segmented open pit method with combined support according to claim 2 is characterized in that: The drilling and point construction method is: construct anchor holes towards 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.

6. The method for mining an unstable ore body in the upper plate by segmented open pit method and combined support according to claim 5 is characterized in that: 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 of ≥1600 MPa.

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

45.

8. The method for mining an unstable ore body in the upper plate by segmented open pit method and combined support according to claim 2 is characterized in that: 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.

9. The method for mining an unstable ore body in the upper plate by segmented open pit method and combined support according to claim 1, characterized in that: In step S4, the mining method of the lower plate area is: S41. Construct upward fan-shaped medium-deep holes in the rock drilling tunnel, use inter-row micro-difference blasting to carry out blasting operations, with a micro-difference time of 50-75ms, and the detonation method is reverse detonation at the bottom of the hole. When the ore collapses, use the upper plate empty area as the free face for retreat mining. First, go back to the mining room stope in the section, then go back to the mining pillar stope. After all the mining in the same section is completed, go to the next section for mining, until the mining of the entire lower plate area is completed; S42. Fresh air flows into the empty area of ​​the stope through the segmented rock drilling tunnel or the middle segmented rock drilling tunnel, and after diluting the blasting smoke, the dirty air flows into the upper middle segment connecting road through the return air connecting tunnel, connecting skylight or the upper segmented rock drilling tunnel, and then merges into the main return air channel through the upper middle segment main transport tunnel; S42. Use remote-controlled shovel loaders to carry out mining operations. At the entrance of the segmented rock drilling tunnel or in the empty area, the collapsed ore is transferred to the segmented chute, and then released into the middle-stage mine car and transported to the surface ore bin through the main hoisting system.

10. The method for mining an unstable ore body in the upper plate by segmented open pit method and combined support according to claim 9, characterized in that: The blasthole diameter of the fan-shaped medium-deep 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°.

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