Method for coordinated recovery of top and bottom pillars based on medium-length holes

Abstract

The application provides a top and bottom pillar collaborative recovery method based on medium-deep holes, belongs to the field of underground mining of metal mines, and obtains top and bottom pillar ore body information through three-dimensional laser scanning to delimit a recovery range; anchor rods are used for reinforcing a roadway in a top pillar area; anchor cables are used for reinforcing a bottom pillar area; a ventilation manway is used as a cutting well, the cutting well is drawn to the width of the roadway to form an initial blasting free surface; downward fan-shaped medium-deep holes are drilled in the top pillar and the bottom pillar, and the holes are arranged in a cross arrangement; directional fracturing technology is used to first blast the side holes of the fan-shaped medium-deep holes, loose blasting is used to increase the free surface of the middle holes, and the remaining holes are finally blasted; a layered millisecond blasting network is used to control the blasting time sequence of the top pillar and the bottom pillar; blasting parameters are controlled to make the ore thrown to the middle section of the goaf to concentrate on ore drawing; and blasting vibration and roof and floor displacement are monitored and regulated in real time. Through the cooperation of drilling design and blasting process, the application realizes the synchronous, safe and efficient recovery of the top and bottom pillars.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of underground mining of metal mines, in particular to a top and bottom pillar cooperative recovery method based on medium-length holes. BACKGROUND

[0002] In the underground mining of metal mines, the top and bottom pillars, as the key structure for maintaining the stability of the stope, have always been a difficulty in mining engineering. The traditional top and bottom pillar recovery adopts a split operation mode (first recover the top pillar and then recover the bottom pillar, or vice versa), which has the following outstanding problems: (1) Long construction period: split recovery needs to wait for the completion of the previous operation (such as roof treatment after top pillar recovery) before starting the subsequent operation, and the single-step cycle is as long as 30-60 days, which prolongs the overall top and bottom pillar recovery cycle by more than 30%; (2) Resource waste: the bottom pillar is prone to cracks due to blasting vibration during top pillar recovery, resulting in ore loss; during bottom pillar recovery, the top pillar residual body may collapse, causing dilution, and the comprehensive recovery rate is usually less than 75%; (3) High safety risk: during split recovery, stress concentration may occur when the top pillar or the bottom pillar is loaded alone, which may cause roof collapse, rib spalling and other accidents, especially in high-stress ore bodies; (4) Difficult operation coordination: the drilling and blasting parameters of the traditional top and bottom pillar recovery are independent of each other, which easily causes blasting interference and increases the complexity of site management.

[0003] Therefore, it is necessary to design a top and bottom pillar cooperative recovery method based on medium-length holes to solve the above problems. SUMMARY

[0004] In view of the technical problems in the background art, the present application provides a top and bottom pillar cooperative recovery method based on medium-length holes, which aims to solve the technical problems of long construction period, low resource recovery rate and high safety risk in traditional top and bottom pillar split recovery.

[0005] The present application provides a top and bottom pillar cooperative recovery method based on medium-length holes, comprising the following steps:

[0006] S1: Obtain the top and bottom pillar ore body information by using three-dimensional laser scanning, and delineate the recovery range;

[0007] S2: Anchor rod reinforcement is used in the top pillar area roadway, and anchor cable reinforcement is used in the bottom pillar area;

[0008] S3: Take the ventilated manway as a cutting well, and draw a groove to the width of the roadway to form an initial blasting free surface;

[0009] S4: Construct upward fan-shaped medium-length holes in the top pillar and downward fan-shaped medium-length holes in the bottom pillar, and adopt cross-hole arrangement;

[0010] S5: using directional fracture technology to blast the edge hole of the fan-shaped medium-length hole first, using loose blasting to increase the free surface of the middle hole, and blasting the remaining holes last; using a layered micro-difference initiation network to control the blasting timing of the top and bottom pillars;

[0011] S6: controlling the blasting parameters to throw the ore to the middle section of the goaf for centralized ore drawing;

[0012] S7: real-time monitoring and control of blasting vibration and roof and floor displacement.

[0013] As a further improvement of the present application, in step S4, the diameter of the upward fan-shaped medium-length hole and the downward fan-shaped medium-length hole is greater than or equal to 60 mm and less than or equal to 80 mm, the hole spacing is greater than or equal to 0.8 m and less than or equal to 1.5 m, and the row spacing is greater than or equal to 1.5 m and less than or equal to 2.0 m.

[0014] As a further improvement of the present application, in step S5, the top and bottom pillars are divided into blasting units, the top pillar is blasted first, and the bottom pillar is lagged behind, with a lag time greater than or equal to 50 ms and less than or equal to 100 ms, and the adjacent blasting units are separated by a micro-difference interval greater than or equal to 30 ms and less than or equal to 50 ms.

[0015] As a further improvement of the present application, in step S2, the diameter of the anchor rod is greater than or equal to 15 mm and less than or equal to 25 mm, and the length is greater than or equal to 2 m and less than or equal to 3 m; the anchor rods are arranged in a row-column pattern, with a longitudinal and transverse spacing of greater than or equal to 1.0 m and less than or equal to 1.2 m; the anchoring force of the anchor rod is not less than 100 kN.

[0016] As a further improvement of the present application, in step S2, the diameter of the anchor cable is greater than or equal to 15 mm and less than or equal to 18 mm, and the length is greater than or equal to 8 m and less than or equal to 12 m; the anchor cables are arranged in a plum blossom pattern, with a spacing between adjacent anchor cables of greater than or equal to 1.5 m and less than or equal to 2.0 m, and the anchoring force of the anchor cable is not less than 200 kN.

[0017] As a further improvement of the present application, the anchoring length of the anchor cable is not less than 3 m, and the free section length is greater than or equal to 5 m and less than or equal to 9 m.

[0018] As a further improvement of the present application, the maximum blasting vibration speed is controlled to be less than or equal to 12 cm / s, and when the roof and floor displacement rate exceeds 5 mm / day, supplemental support is provided.

[0019] As a further improvement of the present application, it further includes filling the goaf formed by the combination after the top and bottom pillars are recovered.

[0020] As a further improvement of the present application, in step S5, a segmented blasting process is used, with the first three rows of holes blasted row by row, and the remaining holes blasted simultaneously in multiple rows.

[0021] As a further improvement to this application, the ore block size after blasting is ≤300mm.

[0022] The beneficial effects of this application are as follows:

[0023] This application provides a method for the coordinated recovery of top and bottom pillars based on medium-deep holes. The method involves using 3D laser scanning to acquire information about the ore bodies in the top and bottom pillars and delineating the recovery area; anchor bolts are used to reinforce the roadway in the top pillar area; anchor cables are used to reinforce the bottom pillar area; ventilation and pedestrian shafts are used as cutting shafts, and the shafts are grooved to the width of the roadway to form the initial blasting free face; upward fan-shaped medium-deep holes are constructed for the top pillars and downward fan-shaped medium-deep holes for the bottom pillars, using a cross-hole layout; directional fracture technology is used to blast the side holes of the fan-shaped medium-deep holes first, and loosening blasting is used for the middle holes to increase the free face, with the remaining holes blasted last; a layered micro-delay blasting network is used to control the blasting sequence of the top and bottom pillars; blasting parameters are controlled to ensure the ore is thrown into the lower middle section of the goaf for concentrated extraction; and blasting vibrations and roof and floor displacements are monitored and controlled in real time. This application utilizes a technical system integrating borehole design, blasting technology, ore extraction process, and safety support to achieve simultaneous recovery of top and bottom pillars. Specifically, it includes steps such as goaf reshaping, borehole construction, blasting optimization, safety protection, and ore extraction coordination. Through 3D modeling and rock mechanics analysis, borehole parameters are collaboratively set. Layered micro-delay blasting and energy gradient release processes are employed to control blasting energy. Combined with top and bottom anchor bolt support and blasting vibration monitoring, this significantly shortens the recovery cycle, improves resource recovery rate, and reduces safety risks. This application is applicable to high-stress, fractured orebody conditions, providing a highly efficient, safe, and resource-utilizing new technical solution for underground metal mining.

[0024] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0025] To more clearly illustrate the technical solution of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0026] Figure 1 This is a longitudinal projection view of the stope of the top and bottom pillar collaborative recovery method based on medium-deep holes in the embodiments of this application;

[0027] Figure 2This is a stope plan view of the top and bottom pillar collaborative recovery method based on medium-deep holes in the embodiments of this application;

[0028] Figure 3 Diagram showing the layout of the cutting groove boreholes;

[0029] Figure 4 This is a diagram showing the layout of the top and bottom pillar blast holes;

[0030] Explanation of reference numerals in the attached diagram: 1. Top column; 2. Bottom column; 3. Anchor cable; 4. Ventilated pedestrian well; 5. Cutting groove downward hole; 6. Cutting groove upward hole; 7. Top column upward fan-shaped medium-deep hole; 8. Bottom column downward fan-shaped medium-deep hole. Detailed Implementation

[0031] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0033] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0034] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0035] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0036] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0037] In underground mining of metal mines, the recovery of top and bottom pillars, as a key structure for maintaining the stability of the mining area, is a difficult point in mining engineering. The traditional phased operation mode has prominent problems such as long construction period, waste of resources, high safety risks and difficulty in operation coordination. The blasting vibration and residual body collapse caused by mutual interference when the top and bottom pillars are recovered one after the other can lead to ore loss and dilution. Stress concentration when the pillars are carried out alone can easily cause accidents such as roof collapse. The risks are particularly significant in high-stress ore bodies. Furthermore, the independent design of drilling and blasting parameters can easily cause blasting interference and increase the complexity of on-site management.

[0038] To address the technical challenges of long construction periods, low resource recovery rates, and high safety risks associated with traditional top and bottom pillar recovery methods, this application provides a method for the coordinated recovery of top and bottom pillars based on medium-deep holes. This method achieves simultaneous, safe, and efficient recovery of top and bottom pillars through a technical system that integrates drilling design, blasting processes, ore extraction processes, and safety support.

[0039] Please refer to Figures 1 to 4 This application provides a method for the coordinated recovery of top and bottom pillars based on medium-deep holes, comprising the following steps:

[0040] S1: Use three-dimensional laser scanning to obtain information on the top and bottom pillar ore bodies and delineate the recovery area;

[0041] Specifically, through three-dimensional laser scanning, the thickness of the top and bottom pillar ore bodies, the volume and shape of the goaf, and the resource quantity information are accurately obtained, and the technically feasible and economically reasonable recovery range is delineated, providing basic data for subsequent drilling design, blasting parameter optimization, and ore extraction planning.

[0042] S2: The roadway in the top pillar 1 area is reinforced with anchor bolts; the roadway in the bottom pillar 2 area is reinforced with anchor cables 3.

[0043] Specifically, a "top anchor bolt + bottom anchor cable" coordinated reinforcement method is adopted. Anchor mesh support is carried out in the roadway of the top pillar 1 area, and high-strength low-relaxation steel strand anchor cable 3 is used for support in the bottom pillar 2 area.

[0044] S3: Using the ventilation pedestrian well 4 as the cutting well, it is grooved to the width of the tunnel to form the initial blasting free face;

[0045] Specifically, the ventilation walkway 4 is used as the cutting shaft. Medium-deep hole blasting technology is used to expand it to the width of the roadway to form a sufficient initial blasting free face. First, the downward cutting groove 5 and the upward cutting groove 6 are constructed. Through micro-differential detonation technology, these blasting holes are detonated sequentially to gradually blast the ventilation walkway 4 into a regular cutting groove, which serves as the compensation space and free face for the subsequent large-scale fan-shaped hole blasting of the top pillar 1 and bottom pillar 2.

[0046] S4: The top column is constructed with an upward fan-shaped medium-deep hole 7 and the bottom column is constructed with a downward fan-shaped medium-deep hole 8, and the holes are arranged in a cross pattern.

[0047] Specifically, a fully hydraulic crawler self-propelled down-the-hole drill rig was used to simultaneously construct the medium-deep holes of the top column 1 and the bottom column 2; the top column 1 used an upward fan-shaped hole, and the bottom column 2 used a downward fan-shaped hole, and a cross-hole layout was used to achieve full coverage of the blasting area; during the construction process, the hole position deviation was strictly controlled to be ≤100mm and the hole depth error to be ≤500mm, and the inclination angle was checked every five holes to ensure drilling accuracy;

[0048] S5: The side holes of the fan-shaped deep holes are blasted first using directional fracture technology, the middle holes are blasted to increase the free surface using loosening blasting, and the remaining holes are blasted last; the blasting sequence of the top column 1 and the bottom column 2 is controlled by a layered micro-delay detonation network.

[0049] Specifically, directional fracturing technology is used to blast the edge holes first to create a flat sliding surface; loosening blasting is used in the middle part of the blast holes to increase the free surface; the remaining blast holes are blasted last to improve the ore discharge effect.

[0050] The first three rows of blast holes were blasted sequentially, with each row creating a new free surface; the remaining blast holes were blasted simultaneously in multiple rows to reduce the total number of blasts and improve efficiency.

[0051] The top column 1 and the bottom column 2 are divided into several blasting units. The timing control of the top column 1 detonating first and the bottom column 2 detonating with a certain delay is achieved by using millisecond-level detonators. The delay time is greater than or equal to 50ms and less than or equal to 100ms. The micro-differential interval between adjacent units is greater than or equal to 30ms and less than or equal to 50ms, and the overall vibration intensity is controlled to be ≤120mm / s.

[0052] The top pillar 1 uses "low unit consumption, high dispersion" charge (the charge amount per hole is reduced by 10-15%) to avoid excessive blasting causing roof instability; the bottom pillar 2 uses "high unit consumption, strong crushing" charge to ensure that it forms a continuous accumulation with the ore falling from the top pillar 1, and the ore block size is controlled within 300mm after blasting.

[0053] S6: Control the blasting parameters to throw the ore into the lower middle section of the goaf for concentrated ore extraction;

[0054] Specifically, by precisely controlling the blasting parameters, the ore from the top and bottom pillars is directionally thrown into the accessible range of the lower and middle sections of the goaf; the loader in the lower and middle sections is coordinated to prepare for operation in advance, so as to achieve seamless connection between blasting and loader transportation; the ore from each deep hole collapse falls into the lower goaf, and after all the top and bottom pillars are recovered, it is extracted from the lower and middle section of the orework.

[0055] S7: Real-time monitoring and control of blasting vibration and top and bottom plate displacement;

[0056] Specifically, 3 to 5 vibration sensors are installed within 100m of the mining area to control the maximum vibration velocity to ≤12cm / s and avoid affecting the stability of the surrounding rock. Deep base point displacement gauges (range 0~500mm) are used to monitor the settlement of the roof and floor. When the displacement rate exceeds 5mm / day, anchor mesh and anchor cable reinforcement are promptly implemented.

[0057] In the technical solution of this application embodiment, the recovery range is precisely delineated by three-dimensional laser scanning, reducing ore loss and dilution; differentiated support of top pillar anchors and bottom pillar anchors specifically reinforces key weak points, providing a reliable working environment for personnel and equipment; cross-hole layout and coordinated blasting technology ensure uniform and thorough crushing of top and bottom pillars, reducing the proportion of large blocks and the foundation, and improving the quality and quantity of mined ore; directional fracture technology effectively protects the surrounding rock and reduces the risk of surrounding rock instability caused by blasting. This application solves the problems of high safety risks, large resource losses, and low production efficiency in traditional pillar recovery through precise digital modeling, optimized cross-hole layout, intelligent blasting control, and differentiated active support synergy, achieving safe, efficient, and green mining.

[0058] Furthermore, in some embodiments, in step S4, the diameters of the deep holes in the upward sector and the deep holes in the downward sector are greater than or equal to 60 mm and less than or equal to 80 mm, the hole spacing is greater than or equal to 0.8 m and less than or equal to 1.5 m, and the row spacing is greater than or equal to 1.5 m and less than or equal to 2.0 m.

[0059] In the technical solution of this application embodiment, the precise hole mesh parameters ensure accurate control of the pillar boundary. The combination of cross-hole layout and reasonable hole spacing can maximize the recovery of pillar resources, significantly reduce ore loss caused by insufficient blasting, promote rock failure under tensile stress, generate more and more uniform cracks, thereby reducing the proportion of large blocks. The uniform block size creates excellent conditions for subsequent loading, transportation and mineral processing operations, and improves the efficiency of the entire production line.

[0060] Furthermore, in some embodiments, in step S5, the top column 1 and the bottom column 2 are divided into blasting units. The top column 1 is detonated first, and the bottom column 2 is detonated with a certain delay, the delay time being greater than or equal to 50ms and less than or equal to 100ms. The micro-difference interval between adjacent blasting units is greater than or equal to 30ms and less than or equal to 50ms. The ore block size after blasting is ≤300mm.

[0061] In the technical solution of this application embodiment, the micro-delay blasting technology controls the blasting vibration within a safe threshold, effectively protecting the roof and floor, and fundamentally reducing the risk of rock instability induced by blasting. The complex overall blasting is decomposed into orderly and controllable unit blasting, avoiding unpredictable concentrated energy release and making the entire operation safer and more reliable. Coordinated initiation and optimized blasting methods ensure that the ore body is fully crushed, reducing residual ore remaining in the stope due to incomplete blasting, bringing the recovery rate close to the theoretical limit, reducing excessive damage and mixing of waste rock and surrounding rock, thereby reducing the ore dilution rate and improving the grade of the raw ore. The blasted ore can directly and efficiently enter the ore extraction process, avoiding secondary crushing and achieving optimization of the entire process cost.

[0062] Further, in some embodiments, in step S2, the anchor bolt has a diameter greater than or equal to 15mm and less than or equal to 25mm, and a length greater than or equal to 2m and less than or equal to 3m; the anchor bolts are arranged in a row-column pattern, with longitudinal and transverse spacing greater than or equal to 1.0m and less than or equal to 1.2m, and the anchoring force of the anchor bolt is not less than 100kN. The anchor cable 3 has a diameter greater than or equal to 15mm and less than or equal to 18mm, and a length greater than or equal to 8m and less than or equal to 12m; the anchor cable 3 is arranged in a staggered pattern, with the spacing between adjacent anchor cables greater than or equal to 1.5m and less than or equal to 2.0m, and the anchoring force of the anchor cable 3 is not less than 200kN. The anchoring length of the anchor cable 3 is not less than 3m, and the free section length is greater than or equal to 5m and less than or equal to 9m.

[0063] In the technical solution of this application embodiment, the coordinated reinforcement of top anchor bolts and bottom anchor cables is adopted. In the top column 1 area, short and dense anchor bolts are arranged in rows to reinforce the shallow surrounding rock in a timely manner and effectively suppress the risk of roof delamination and collapse. At the same time, in the bottom column 2 area, long and strong anchor cables 3 are arranged in a quincunx pattern to deeply anchor and stabilize the rock mass and significantly improve the shear resistance and anti-heave capacity, forming a zoned coordinated support system. While ensuring the safety of mining operations, it achieves precise allocation of support resources and optimization of cost-effectiveness.

[0064] Furthermore, in some embodiments, reinforcement support is provided when the maximum blasting velocity is controlled to be ≤12cm / s and the displacement rate of the top and bottom plates exceeds 5mm / day.

[0065] In the technical solution of this application embodiment, controlling the maximum blasting vibration velocity effectively reduces the disturbance and damage of blasting to the surrounding rock. At the same time, the displacement rate of the top and bottom plates is monitored in real time and reinforcement support is initiated in time when it exceeds 5mm / day. This not only ensures the long-term stability of the surrounding rock and the safety of operation, but also realizes the precise input and dynamic optimization of support measures.

[0066] Furthermore, in some embodiments, the method also includes filling the merged goaf after the top and bottom pillars have been recovered.

[0067] In the technical solution of this application embodiment, after the top and bottom pillars are recovered synchronously, the two goaf areas are merged to form a larger goaf area. In order to reduce the risk of ground pressure activity, the merged goaf area is filled from the upper and middle sections.

[0068] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific technologies or conditions are not specified in the embodiments, they shall be performed in accordance with the technologies or conditions described in the literature in this field or in accordance with the product manual.

[0069] Example 1:

[0070] This embodiment provides a method for the coordinated recovery of top and bottom pillars based on medium-deep holes, including the following steps:

[0071] S1: Use three-dimensional laser scanning equipment to perform a full-range scan of the mining area, obtain the thickness distribution of the ore body of the top pillar 1 and bottom pillar 2, accurately measure the volume and shape of the goaf and the amount of residual resources, and delineate the recovery range in combination with the ore and rock mechanical parameters.

[0072] In this embodiment, the average thickness of the top pillar 1 is 5.2m, the average thickness of the bottom pillar 2 is 4.8m, and the volume of the goaf is approximately 8000m³. 3 ;

[0073] S2: The roadway in the top column 1 area uses threaded steel anchor bolts with a diameter of 20mm and a length of 2.5m, arranged in rows and columns of 1.0m×1.0m, and laid with metal mesh with a grid size of 200mm×200mm. The actual measured anchoring force of the anchor bolts is 110kN.

[0074] The bottom column 2 area uses high-strength, low-relaxation steel strand anchor cable 3 with a diameter of 15.2mm, a length of 10m (3m anchor section and 7m free section), an anchoring force of 220kN, and arranged in a 1.8m×1.8m quincunx pattern. The anchor cable 3 forms a strong lifting constraint on the bottom rock mass.

[0075] S3: Using the ventilation pedestrian well 4 as the cutting well, the medium-deep hole blasting is used to pull the groove to the width of the roadway (3.2m) to form the initial blasting free face. During the specific construction, the downward hole 5 and the upward hole 6 of the cutting groove are drilled for blasting to provide pressure relief space for the subsequent fan-shaped hole blasting of the top and bottom pillars.

[0076] S4: The CLQ-100A down-the-hole drill rig is used to simultaneously construct the upward fan-shaped medium-deep hole 7 on the top column and the downward fan-shaped medium-deep hole 8 on the bottom column; the drilling diameter is 65mm, and the hole pattern parameters (hole spacing × row spacing) are 1.2m × 1.5m, with the holes arranged in a crisscross pattern;

[0077] Among them, the average depth of the fan-shaped deep hole 7 on the top column is 5.5m, and the average depth of the fan-shaped deep hole 8 on the bottom column is 8.0m. During construction, the hole position deviation is less than 95mm, the hole depth error is less than 450mm, and the inclination angle is checked every five holes to ensure that the drilling accuracy meets the design requirements.

[0078] S5: Side hole of deep hole in fan shape (e.g.) Figure 4 The blast holes within the yellow area in the image were blasted using directional fracture blasting to create a smooth slip surface; the intermediate blast holes (such as...) Figure 4 The blast holes within the purple area in the image are loosened by blasting to increase the free surface; the remaining blast holes (such as...) Figure 4 The blasting of the blast holes within the blue area in the image is completed by final detonation, improving the ore extraction effect;

[0079] The first three rows of blast holes were blasted one row at a time, while the remaining blast holes were blasted in multiple rows simultaneously.

[0080] Initiation network: Top post 1 detonates first, bottom post 2 detonates 80ms later, and the micro-differential interval between adjacent units is 40ms; the single-hole charge of top post 1 is reduced by 12% compared to the conventional method, and bottom post 2 is charged according to the design unit consumption.

[0081] Post-blast ore block size testing showed that over 90% of the ore blocks were ≤280mm in size, meeting the ore extraction requirements.

[0082] S6: After blasting, enter the working face after a 30-minute interval to achieve continuous ore extraction. The ore extraction after each blast is controlled at 30% of the ore collapse volume, and the remaining ore is temporarily stored in the goaf as a buffer layer.

[0083] S7: Blasting vibration monitoring: Four vibration sensors were installed within a range of 50-100m around the mining area. The measured maximum vibration velocity was 9.5-11.2cm / s, which meets the control requirement of ≤12cm / s.

[0084] Top and bottom plate monitoring: The deep foundation point displacement gauge shows that the average daily settlement of the top and bottom plates is 2~3mm, which does not exceed the warning value of 5mm / d, and the surrounding rock stability is good;

[0085] S8. After all the top and bottom pillars are recovered (total construction period 42 days), tailings cemented backfilling is carried out from the upper and middle section external roadway to the merged goaf area. The strength of the backfill body reaches more than 3MPa, effectively controlling ground pressure activity.

[0086] In this embodiment, the amount of resources recovered from the top and bottom columns increased by 18% compared to the traditional method, and the overall recovery rate reached 88.5%. No safety accidents such as top plate collapse or sidewall spalling occurred, which verified the effectiveness and safety of the present invention.

[0087] This application has the following significant advantages:

[0088] (1) The construction period is greatly shortened: the recovery cycle of the top and bottom pillars is reduced from the traditional 60-120 days to 30-45 days, and the overall mining efficiency of the mining area is increased by more than 40%;

[0089] (2) Significantly improved resource recovery rate: Eliminating the impact of blasting interference and residues in staged recovery, the overall recovery rate has increased from less than 75% to 85-90%;

[0090] (3) Reduced safety risks: The top and bottom pillars bear the load and relieve pressure simultaneously, avoiding stress concentration and reducing the risk of roof collapse by more than 60%, which is suitable for high stress and fractured ore body conditions;

[0091] (4) Enhanced operational coordination: Through integrated design and collaborative processes, blasting interference and process waiting are reduced, and on-site management efficiency is improved.

[0092] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for top-bottom pillar coordinated recovery based on medium-length hole, characterized in that, The method comprises the following steps: S1: obtaining top and bottom pillar ore body information by using three-dimensional laser scanning, and delineating the recovery range; S2: using anchor rods to reinforce the roadway in the top pillar area, and using anchor cables to reinforce the roadway in the bottom pillar area; S3: taking the ventilation manway as a cutting well, and slotting it to the width of the roadway to form an initial blasting free surface; S4: constructing upward fan-shaped medium-length holes in the top pillar and downward fan-shaped medium-length holes in the bottom pillar, and arranging the holes in a cross arrangement; S5: using directional fracturing technology to first blast the side holes of the fan-shaped medium-length holes, using loose blasting to increase the free surface of the middle holes, and finally blasting the remaining holes; and using a layered millisecond detonation network to control the blasting timing of the top pillar and the bottom pillar; S6: controlling the blasting parameters to make the ore thrown to the middle section of the goaf to concentrate the ore; S7: real-time monitoring and regulation of blasting vibration and roof and floor displacement.

2. The medium-length hole based top-pillar coordinated recovery method according to claim 1, characterized in that, In step S4, the diameters of the upward fan-shaped medium-length holes and the downward fan-shaped medium-length holes are greater than or equal to 60 mm and less than or equal to 80 mm, the hole spacing is greater than or equal to 0.8 m and less than or equal to 1.5 m, and the row spacing is greater than or equal to 1.5 m and less than or equal to 2.0 m.

3. The medium-length hole based top-pillar coordinated recovery method according to claim 1, characterized in that, In step S5, the top pillar and the bottom pillar are divided into blasting units, the top pillar is blasted first, the bottom pillar is blasted with a lag time greater than or equal to 50 ms and less than or equal to 100 ms, and the adjacent blasting units are separated by a millisecond interval greater than or equal to 30 ms and less than or equal to 50 ms.

4. The medium-length hole based top-pillar coordinated recovery method according to claim 1, characterized in that, In step S2, the diameters of the anchor rods are greater than or equal to 15 mm and less than or equal to 25 mm, and the lengths are greater than or equal to 2 m and less than or equal to 3 m; the anchor rods are arranged in a row-column pattern, and the longitudinal and transverse spacings are both greater than or equal to 1.0 m and less than or equal to 1.2 m; and the anchoring force of the anchor rods is not less than 100 kN.

5. The medium-length hole based top-pillar coordinated recovery method according to claim 1, characterized in that, In step S2, the diameters of the anchor cables are greater than or equal to 15 mm and less than or equal to 18 mm, and the lengths are greater than or equal to 8 m and less than or equal to 12 m; the anchor cables are arranged in a quincunx pattern, and the spacings between adjacent anchor cables are both greater than or equal to 1.5 m and less than or equal to 2.0 m; and the anchoring force of the anchor cables is not less than 200 kN.

6. The medium-length hole based top-pillar and bottom-pillar coordinated recovery method according to claim 5, characterized in that, The anchoring length of the anchor cable is not less than 3 m, and the free section length is greater than or equal to 5 m and less than or equal to 9 m.

7. The medium-length hole based top-sub pillar coordinated recovery method according to claim 1, characterized in that, The maximum blasting vibration velocity is controlled to be less than or equal to 12 cm / s, and when the roof and floor displacement rate exceeds 5 mm / day, supplemental support is performed.

8. The medium-length hole based top-sub pillar coordinated recovery method according to claim 1, characterized in that, After the top and bottom pillar recovery is completed, the combined goaf is filled.

9. The medium-length hole based top-sub-pillar coordinated recovery method according to claim 1, characterized in that, In step S5, a segmented blasting process is used, the first three rows of holes are blasted row by row, and the remaining holes are blasted simultaneously in multiple rows.

10. The medium-length hole based top-sub pillar coordinated recovery method according to claim 9, characterized in that, After blasting, the ore size is less than or equal to 300 mm.

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