Safe recovery construction method for middle-section inner-pointed ore body

Abstract

The invention discloses a safe recovery construction method for a middle-section inner pointed ore body, and relates to the technical field of mining. The method comprises the three steps of accurate mining engineering construction, stoping blasting construction and ore transportation and ventilation. In the mining preparation project, a hanging cage method and an ordinary method are combined to construct a shaft and a raise, and arrangement of a chamber and a funnel is optimized; a bidirectional blast hole is combined with a fractional millisecond millisecond detonation process in the stoping blasting process, and beam-shaped holes are specifically arranged to recover peach-shaped jambs; an electric rake way and draw shaft mode is adopted for ore transportation, and an independent air inlet and return system is matched. According to the method, top pillars do not need to be reserved, remaining ores and bottom pillars can be jointly stoped, the problems that the middle-section inner pointed ore body resource recovery rate is low, roadways are prone to being damaged by blasting, and construction safety is poor are solved, mining efficiency and economical efficiency are improved, and the method is suitable for safe and efficient recovery of the middle-section inner pointed ore body.

Description

Technical Field

[0001] This invention relates to the field of mining technology, and in particular to a method for the safe recovery of pinch-out ore bodies in intermediate sections. Background Technology

[0002] In the mining industry, pinch-out ore bodies in the middle section, located between the upper and lower middle sections, have always been a challenging area for mining operations due to their irregular shape and complex burial conditions. The top and bottom of such ore bodies are often connected to the roadways and pillars of the upper and lower middle sections. Conventional mining methods typically require the installation of top and bottom pillars to ensure the stability of the roadway structure. This results in a large amount of ore resources being retained, leading to generally low resource recovery rates and making it difficult to meet the needs of mines for efficient resource utilization.

[0003] Meanwhile, the development and transportation conditions of the pinch-out ore body in the middle section are limited, making the layout of the preparatory engineering difficult. Traditional preparatory engineering often adopts a single tunneling method, which is poorly adaptable to shafts and chambers of different depths and surrounding rock conditions. This not only results in low construction efficiency but also easily leads to safety hazards such as surrounding rock collapse. In the blasting operation, conventional one-time blasting methods release concentrated energy and have a large blasting impact force, which can easily damage critical facilities such as electric scraper tracks and ore passes, leading to increased roadway maintenance costs and even affecting the normal progress of subsequent mining operations.

[0004] Furthermore, pinch-out ore bodies in the middle section are often accompanied by residual ore and pillars. These residual ore bodies are scattered and poorly integrated with the existing production system, making individual mining costly and posing significant safety risks. Traditional mining techniques lack joint mining solutions for these scattered ore bodies, further exacerbating the problem of resource waste.

[0005] Currently, the industry lacks a mature solution for mining mid-level pinch-out ore bodies that balances resource recovery rate, construction safety, and operational efficiency. Therefore, developing a construction method capable of safely and efficiently recovering mid-level pinch-out ore bodies is of significant practical importance for improving mine resource utilization, reducing mining costs, and ensuring operational safety. Summary of the Invention

[0006] The purpose of this application is to provide a safe construction method for recovering pinch-out ore bodies in the middle section, which can solve the existing technical problems of low resource recovery rate of pinch-out ore bodies in the middle section, easy damage to surrounding roadways by blasting, poor construction safety and low efficiency.

[0007] To achieve the above objectives, this application provides the following technical solution: a method for safe recovery of a pinch-out ore body in a mid-section, comprising...

[0008] S1: Construction of the mining preparation project, in the -295m middle section, the No. 1 guide section electric scraper track and electric scraper chamber are arranged through the 33 line. The No. 1 personnel shaft and the No. 2 ore pass are arranged in the guide section electric scraper track. The No. 1 personnel shaft is connected to the -255m middle section. The No. 2 ore pass is constructed to the -275m horizontal elevation (the ore pass is precisely connected to the -275m ore extraction level, shortening the ore transfer distance and reducing energy consumption and ore loss during the transfer process).

[0009] A return air duct is arranged at the end of the guide section to connect with the -295m transport roadway along the vein;

[0010] In the -295m middle section, the 32A line is arranged to connect the No. 3 return air well with the N14# power line in the -255m middle section, forming a complete air intake and return system with the return air duct, realizing the directional flow of air, improving ventilation efficiency, and timely expelling toxic and harmful gases generated by the explosion.

[0011] An N7# electric scraper track is installed at an elevation of -275m, using a double-sided staggered funnel arrangement with a funnel spacing of 5m and a tentatively set bottom pillar height of 5m. The mining width is equal to the ore body thickness, and the mining height ranges from -270m to -250m. The double-sided staggered funnel arrangement increases the ore receiving area and avoids ore production interruptions caused by blockage of a single funnel. The funnel spacing and bottom pillar height parameters are adapted to the ore body thickness to ensure ore receiving stability. The mining width and mining height are set according to the actual range of the ore body to avoid over-excavation or under-excavation and improve resource utilization.

[0012] Cutting chambers are arranged along the strike of the ore body at horizontal elevations of -270m and -260m, respectively. Vertical trench chambers are arranged perpendicular to the strike of the ore body. Vertical trench lifts are arranged in the vertical trench chambers to connect with the upper layer. The cutting chambers provide the initial free face for blasting, reducing the consumption of explosives per unit. The vertical trench lifts connect with the upper layer, further expanding the free face space, making it easier to release blasting stress and improving the ore body crushing effect. The layered arrangement of cutting chambers adapts to the shape of the pinch-out ore body in the middle section, realizing layered and segmented mining.

[0013] The vertical shafts #4, #5, and #6 were constructed using the conventional method, while the pedestrian shaft #1, chute #2, and return air shaft #3 were constructed using the suspended bucket method. The primary function of the vertical shafts is to provide free surfaces. The conventional method is cost-effective and simple, meeting the construction requirements. The pedestrian shafts, chute shafts, and return air shafts are critical passageways. The suspended bucket method eliminates the need for scaffolding, resulting in high construction efficiency and ensuring the verticality of the shafts, thus preventing subsequent passage and transport functions from being affected by shaft tilt.

[0014] S2: The blasting operation for mining involves multiple blasting operations using vertical upward medium holes and vertical downward deep holes with the vertical trench lift as the free face, and wire guide holes with the vertical trench chamber as the free face. The combination of bidirectional blasting holes and different free faces achieves three-dimensional crushing of the ore body and reduces blasting dead zones. The multiple blasting operations can control the energy release of each blast, reduce the impact damage to the surrounding roadways, and facilitate the adjustment of subsequent parameters based on the effect of the previous blast.

[0015] The deep holes were drilled using an SKQ-100 down-the-hole drill, with a borehole diameter of φ90mm. The borehole grid in the vertical trench chamber was 2.0×2.0m, with a row spacing of 2.1m and a bottom hole distance of 1.8~2.5m. φ70mm strip-shaped emulsion explosives were continuously charged throughout the hole.

[0016] The upward-facing central hole was drilled using a YGZ90 pneumatic rock drill with a borehole diameter of φ55mm. The borehole grid size of the vertical trench chamber was 1.0×1.0m, the row spacing was 1.3m, and the bottom distance of the holes was 1.2~2.0m. φ45mm strip-shaped emulsion explosive was continuously charged throughout the hole, and digital electronic detonators were used for detonation.

[0017] In the -255m middle section transport roadway, bundled holes are arranged in chambers 8 and 9 for the recovery of peach-shaped ore pillars. The bundled holes are specifically designed to target the irregularly shaped peach-shaped ore pillars, so as to achieve precise recovery of residual ore bodies at the edges and corners and avoid resource waste.

[0018] The mining area was blasted in three stages, using electronic detonators for segmented millisecond-delay detonation. The same row of holes was detonated in the same segment, with a 50ms detonation interval between rows. The segmented millisecond-delay detonation allowed the blasting energy to be released row by row, reducing the intensity of blasting vibration and protecting surrounding facilities such as electric scraper tracks and ore passes. The same row of holes being detonated in the same segment ensured the synchronous crushing of the ore body, while the 50ms interval between rows avoided the superposition of blasting stress and ensured the orderly collapse of the ore.

[0019] S3: Ore handling and ventilation. The mined ore is scraped into the No. 2 pass through the N7# electric scraper funnel at the -275m level, and then transferred to the -295m middle section for loading and transportation. Fresh air enters the No. 1 foot shaft from the -295m middle section and then enters the -275m level electric scraper, while the polluted air is discharged to the surface through the No. 3 return air shaft.

[0020] As a preferred embodiment of this example, the construction steps of the suspended tank method are as follows: a drilling rig is arranged in the -255m section to drill a 100mm diameter central hole along the center of the well; a hoisting device is installed horizontally at -255m, and a steel rope is passed through the central hole and connected to the suspended tank in the -295m section.

[0021] After completing the rock drilling and explosive loading operations on the suspended container, the container is lowered to carry out the blasting.

[0022] Slag is removed at the -295m level. A bottom-up construction sequence is adopted. This bottom-up construction allows for automatic slag removal by utilizing the self-weight of the blasted slag, reducing the amount of manual slag removal work. At the same time, the lower roadway is formed first to provide a safety guarantee for the upper construction.

[0023] As a preferred implementation method in this embodiment, the construction sequence of the preparatory engineering is as follows: first, construct the electric scraper track, electric scraper chamber, and return air duct of the No. 1 guide section in the -295m middle section (prioritizing the construction of basic channels for ore extraction and ventilation, providing transportation and ventilation guarantees for subsequent shaft construction and personnel operations, and avoiding interference from cross-operations); then, widen the shaft location by brushing the sidewalls (reserving space for shaft construction in advance to avoid damage to the existing roadway during subsequent construction and ensure the stability of the roadway structure); subsequently, at -255m... The hoisting chamber in the middle section of the mine shaft is constructed using the hoisting method. Next, the N7# electric scraper chamber, scraper track, and funnel are constructed at the -275m level. Then, the cutting layer and vertical shaft are constructed at the -270m and -260m levels respectively. Finally, chambers #8 and #9 are constructed in the middle section at -255m. The chamber construction is carried out only after the main ore body preparation work is completed to avoid interference between chamber construction and the main project. The chambers are used as recovery pillars, achieving joint recovery of the main ore body and residual pillars, thus improving resource recovery rate.

[0024] As a preferred embodiment of this example, the phased blasting specifically involves the first blasting of some holes in rows C1-C4 of the No. 2 vertical trench, some holes in rows C1-C2 of the deep holes in the No. 2 vertical trench, and all holes in rows P1-P19 of the No. 8 chamber, totaling 102 holes. The first blasting prioritizes detonating the blast holes in key areas to form the initial ore passage and free face, creating conditions for subsequent blasting. All blast holes in the No. 8 chamber are detonated, allowing for the early recovery of the peach-shaped ore pillars and preventing the pillars from collapsing and blocking the passage during the blasting of the main ore body.

[0025] The second blasting involved the remaining deep holes in the No. 2 vertical trench, the middle holes in rows S1-S7 and the deep holes in rows S1-S4 of the No. 3 chamber, totaling 94 holes. The remaining deep holes and the blast holes in the No. 3 chamber were detonated to further expand the crushing range and release the stress in the ore body. The amount of explosives and the number of holes were reasonably controlled to avoid excessive blasting vibration that could damage the roadway.

[0026] The third blasting operation involved 200 holes, including the middle holes in rows N1-N11 of chamber 4, the deep holes in rows N1-N7, and all holes in rows P1-P12 of chamber 9. Finally, the blast holes in chambers 4 and 9 were detonated to recover the remaining ore body, achieving comprehensive recovery of the ore body throughout the entire mining area. Although the number of holes was the largest, the blasting was carried out in stages to ensure the blasting effect while controlling the vibration intensity.

[0027] As a preferred embodiment of this method, the method eliminates the need for horizontal pillars at the top. It combines the mining of the remaining ore around the -255m horizontal transport roadway and the structural pillars at the bottom of the N14# electric scraper roadway, thus eliminating the need for horizontal pillars at the top and completely solving the problem of ore retention at the top in traditional mining, thereby improving the resource recovery rate. The combined mining of the remaining ore and the bottom pillars incorporates scattered ore bodies into a unified mining system, reducing the cost and safety risks of individual mining.

[0028] As a preferred implementation method in this embodiment, three blasting operations are performed: after all the blast holes within the first detonation range are loaded with explosives, the blasting is detonated. After a few days, some ore is extracted from the bottom first, and then the blast holes within the second detonation range are tested, loaded with explosives, and detonated again. After another few days, some ore is extracted from the bottom, and the above operation is repeated for the third detonation.

[0029] The above-mentioned intermittent ore extraction after blasting avoids ore accumulation and blockage of the funnel and chute, ensuring the continuity of subsequent blasting; the borehole measurement process can promptly detect deformation or blockage of the blast holes, ensuring the charging effect and improving the blasting success rate;

[0030] The first blasting will detonate the C1 row #1 holes and C2 row #1 and #2 holes in the -270~-260m deep holes. Detonating them first will provide a channel for the ore to fall into the upper -260~-250m middle holes. Prioritizing the detonation of the lower deep holes will create a channel for the ore to fall in advance, preventing the ore from accumulating after the upper middle holes are blasted and ensuring the efficiency of blasting.

[0031] Subsequently, the blast holes in rows C1, C2, C3, and C4 around the No. 6 vertical shaft above 260m were detonated sequentially. Then, the blast holes in each row of the No. 8 chamber were detonated one row at a time. The blast holes around the vertical shaft were detonated first to further expand the free face and reduce the explosive consumption per unit of the upper ore body. The blast holes in the No. 8 chamber were detonated one row at a time to achieve uniform crushing of the peach-shaped ore pillar, reduce the proportion of large pieces, and reduce the cost of secondary crushing.

[0032] In summary, the technical effects and advantages of this invention are as follows:

[0033] 1. This invention eliminates the need for horizontal pillars at the top. It combines the mining of residual ore around the -255m horizontal transport roadway with the bottom structural pillars, reducing resource loss and improving ore recovery rate. By eliminating the need for horizontal pillars at the top, and simultaneously mining the residual ore around the -255m horizontal transport roadway with the bottom structural pillars of the N14# electric scraper roadway, this invention completely solves the problems of resource retention and difficulty in recovering corner ore bodies in traditional mid-section pinch-out ore body mining. In practical application, the ore recovery rate has been improved compared to traditional methods, significantly reducing resource waste.

[0034] 2. In this invention, a shaft construction method combining the suspended bucket method and the conventional method is adopted, which avoids the risks of high-altitude operations when erecting scaffolding in steep shafts; the mining blasting adopts a segmented millisecond micro-delay detonation process to precisely control the intensity of blasting vibration, reduce the impact and damage to key facilities such as surrounding electric scraper tracks and chutes, and reduce roadway maintenance costs; the independent intake and return air system ensures clean airflow at the working face, effectively reducing the harm of harmful gases and dust to workers;

[0035] 3. In this invention, the double-sided staggered arrangement of funnels improves ore receiving efficiency and reduces the frequency of funnel blockage; the blasting scheme of upper and lower bidirectional blast holes combined with the free face of the vertical trench achieves uniform crushing of the ore body, reduces the proportion of large blocks, and reduces the workload of secondary crushing; the operation mode of blasting in stages and extracting ore at intervals ensures the continuity of mining operations, and the daily output of the stope is improved compared with traditional methods; at the same time, there is no need to leave protective pillars and repeatedly repair roadways, thus reducing the overall mining cost. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a plan view of the N7# electric guide section #1 at -295m, used to show the layout of the electric scraper track, electric scraper chamber and shaft in the N7# electric guide section #1 at -295m.

[0038] Figure 2 This is a plan of the N7# electric hoist (-275m horizontal) at -295m, used to show the layout of the electric hoist track and hopper at the -275m horizontal level;

[0039] Figure 3 This is a plan of the N7# electric cutting system at -295 meters (horizontal at -270 meters), used to show the structure of the -270m horizontal cutting layer and the vertical trench chamber;

[0040] Figure 4 This is a plan of the N7# electric cutting system at -295 meters (horizontal at -270 meters), used to show the structure of the -270m horizontal cutting layer and the vertical trench chamber;

[0041] Figure 5 This is a plan view of the N7# electrical composite structure in the -255m middle section, used to show the location of chambers 8# and 9# and the transport roadway in the -255m middle section;

[0042] Figure 6 This is the first cross-sectional view of the N7# power line at -295 meters, used to show the vertical structure of the mining area and the connection relationship of the shaft;

[0043] Figure 7 This is the second profile of the N7# power plant at -295 meters, used to supplement the display of vertical blasting and ore body distribution in the mining area;

[0044] Figure 8 for Figure 7 Enlarged schematic diagram of point a in the middle. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] This implementation focuses on the pinch-out ore body in the middle section of the N7# stope of the 32-33 line in the -295m section of the Tianmashan mining area. The ore body is located between the -255m and -295m sections, with a thickness of 5-8m, a north-south strike, an eastward dip, and a dip angle of 60°-80°. The main metallic minerals are pyrite, chalcopyrite, and gold, while the gangue minerals are calcite and dolomite. The top and bottom plates of the ore body are moderately stable marble, with a geological mineral quantity of 7158t, a gold grade of 5.4g / t, and a sulfur grade of 22.7%.

[0047] S1: Preparation and Construction Engineering

[0048] Construction of the -295m middle section began with the construction of the No. 1 guide section electric scraper roadway at the location where the 33 line crosses the -295m middle section. The roadway measures 11.3m × 2m × 2m. At the end of the guide section, a 3.5m × 3.5m × 2m electric scraper chamber was constructed. Subsequently, a 5.2m × 2m × 2m return air duct was constructed at the end of the guide section, connecting with the -295m transport roadway along the vein. Finally, the pre-designated locations of the No. 1 pedestrian shaft, No. 2 chute, and No. 3 return air shaft were enlarged by brushing to meet the shaft construction size requirements.

[0049] The shaft construction includes a suspended chamber (3.8m × 2.0m × 3.8m) at the corresponding location in the -255m section. The suspended chamber method is used to construct the No. 1 personnel shaft, No. 2 ore pass, and No. 3 return air shaft. The specific steps are as follows: a drilling rig is positioned in the -255m section to drill a 100mm diameter center hole along the center of the shaft; a winch is installed, and a steel cable is threaded through the center hole and connected to the suspended chamber in the -295m section; after completing rock drilling and explosive loading operations on the suspended chamber, the chamber is lowered for blasting; slag is removed at the -295m level, with construction proceeding from bottom to top. The No. 1 personnel shaft and No. 3 return air shaft are connected to the -255m section, and the No. 2 ore pass is constructed to the -275m level.

[0050] The construction of the -275m level project involves entering the -275m level through the No. 1 foot shaft, constructing the N7# electric scraper chamber (3.5m×3.5m×2.0m) and the electric scraper track (30m×2.0m×2.0m), connecting the electric scraper track with wells No. 1, No. 2, and No. 3; constructing double-sided staggered funnels on both sides of the electric scraper track, with a funnel spacing of 5m and funnel dimensions of 3.0m×2.0m×5.0m.

[0051] The cutting layer and vertical trench ceiling construction: The cutting layer, with a total length of 20.3m, is constructed at the -270m level. It is divided into three chambers: Chamber 1, Vertical Trench Chamber 1, and Chamber 2. The dimensions of Vertical Trench Chamber 1 are 9.3m × 4.2m × 2.7m. The width and height of Chambers 1 and 2 are both 2.7m. Vertical trench ceilings 4 and 5 are constructed upwards from the Vertical Trench Chamber 1, with dimensions of 2.0m × 2.0m × 7.3m. A 13m long connecting tunnel was constructed at the -260m level to the boundary of the ore block, followed by a 21.2m long intermediate cutting layer, which is divided into chamber #3, vertical trench chamber #2, and chamber #4. The dimensions of vertical trench chamber #2 are 9.3m × 4.2m × 2.7m. Vertical trench ceiling #6 was constructed upwards from the chamber of vertical trench chamber #2, connecting with the -255m middle section.

[0052] The construction of the -255m intermediate chambers includes the construction of chambers #8 and #9, each measuring 2.7m x 2.7m x 2.7m, on the N14# electric scraper roadway. These chambers are used to arrange the peach-shaped pillars for bundled hole mining.

[0053] S2: Mining blasting operation

[0054] The borehole layout and drilling were carried out at a horizontal depth of -260m, with vertically upward intermediate holes and vertically downward deep holes. The downward deep holes were drilled using an SKQ-100 down-the-hole drill rig with a diameter of φ90mm. The borehole grid in the vertical trench chamber was 2.0×2.0m, with a row spacing of 2.1m and a bottom-to-bottom distance of 1.8~2.5m. The upward intermediate holes were drilled using a YGZ90 pneumatic rock drill with a diameter of φ55mm. The borehole grid in the vertical trench chamber was 1.0×1.0m, with a row spacing of 1.3m and a bottom-to-bottom distance of 1.2~2.0m. Nineteen rows of bundled holes were arranged in chamber #8, and twelve rows of bundled holes were arranged in chamber #9.

[0055] For charging and detonation, φ70mm strip-shaped emulsion explosive is used for continuous charging of the entire hole in the downward deep holes, and φ45mm strip-shaped emulsion explosive is used for continuous charging of the entire hole in the upward middle holes, equipped with digital electronic detonators; the mining area is blasted in three stages, using a segmented millisecond micro-delay detonation method, with holes in the same row detonated in the same segment, and the interval between rows is 50ms.

[0056] First blasting: 102 holes were charged and detonated, including some holes in rows C1-C4 of the central hole in the No. 2 vertical trench, some holes in rows C1-C2 of the deep hole in the No. 2 vertical trench, and all holes in rows P1-P19 of the No. 8 chamber. The total explosive charge was 814.1 kg. The detonation sequence was as follows: first, detonate the No. 1 hole in row C1 and the No. 1 and No. 2 holes in row C2 of the deep hole at -270~-260m to form the ore passage, and then detonate the upper central hole and the blasting holes in the No. 8 chamber.

[0057] Three days after the first blast, some ore was lowered, and the boreholes in the second blasting area were measured and charged. The remaining deep holes in the No. 2 vertical trench, the middle holes in rows S1-S7 and the deep holes in rows S1-S4 of the No. 3 chamber were detonated, totaling 94 holes, with a total explosive charge of 985.4 kg.

[0058] Three days after the second blast, the ore was extracted. The explosive charge was then applied to the area to be blasted for the third blast. The explosives were detonated in the middle holes of rows N1-N11, the deep holes of rows N1-N7, and all holes of rows P1-P12 in chamber 4, totaling 200 holes, with an explosive charge of 1683.6 kg.

[0059] S3: Ore handling and ventilation

[0060] The mined ore is raked into the No. 2 ore pass through the N7# electric scraper funnel at the -275m level, then transferred to the 33 line cross vein in the -295m middle section, and then raked into the loading platform through the No. 1 guide section electric scraper, loaded into 0.9m³ mine car sets, and transported to the concentrator by a 3-ton electric locomotive set.

[0061] Fresh air enters the No. 1 pedestrian shaft from the south side of the -295m middle section and flows into the N7# electric scraper track working face at the -275m level; polluted air is collected through the return air duct and flows into the north wing ventilation shaft of the -255m middle section through the No. 3 return air shaft, and is finally discharged to the ground surface, ensuring that the wind speed at the working face is not less than 0.3m / s.

[0062] In this embodiment, the above-mentioned method was used to recover the pinch-out ore body in the middle section of the N7# stope. A total of 8470t of ore was blasted, with a gold grade of 5.81g / t and a single explosive consumption of only 0.41kg / t. No safety accidents such as roadway damage or surrounding rock collapse occurred during the mining process. The ore recovery rate was increased by 18% compared with the traditional method, and the overall mining cost was reduced by 22%, achieving the goal of safe, efficient and economical ore body recovery.

[0063] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A safe recovery construction method for a middle section pinch ore body, characterized in that: include S1: During the preparation and construction of the mining project, the No. 1 guide section electric scraper track and electric scraper chamber are arranged in the middle section of the -295m section of the 33 line. The No. 1 manhole and the No. 2 chute are arranged in the electric scraper track of the guide section. The No. 1 manhole is connected to the middle section of the -255m section, and the No. 2 chute is constructed to the horizontal elevation of -275m. A return air duct is arranged at the end of the guide section to connect with the -295m transport roadway along the vein; In the -295m middle section, the 32A line is arranged to connect the No. 3 return air well with the N14 power line in the -255m middle section; The N7# electric scraper track is set up at the -275m elevation. The funnels are arranged in a staggered manner on both sides with a funnel spacing of 5m. The bottom pillar height is tentatively set at 5m. The mining width is equal to the thickness of the ore body. The mining height is from the -270m to the -250m elevation. Cutting chambers are arranged along the strike of the ore body at horizontal elevations of -270m and -260m respectively, and vertical trench chambers are arranged perpendicular to the strike of the ore body. Vertical trench ceilings are arranged in the vertical trench chambers to connect with the upper layer. The vertical shafts #4, #5, and #6 were constructed using the conventional method, while the pedestrian shaft #1, chute #2, and return air shaft #3 were constructed using the suspended bucket method. S2: The blasting operation for mining is carried out by using vertical upward medium holes and vertical downward deep holes with the vertical trench ceiling as the free face, and the wiring holes with the vertical trench chamber as the free face for multiple blasting operations. The deep holes were drilled using an SKQ-100 down-the-hole drill, with a borehole diameter of φ90mm. The borehole grid in the vertical trench chamber was 2.0×2.0m, with a row spacing of 2.1m and a bottom hole distance of 1.8~2.5m. φ70mm strip-shaped emulsion explosives were continuously charged throughout the hole. The upward-facing central hole was drilled using a YGZ90 pneumatic rock drill with a borehole diameter of φ55mm. The borehole grid size of the vertical trench chamber was 1.0×1.0m, the row spacing was 1.3m, and the bottom distance of the holes was 1.2~2.0m. φ45mm strip-shaped emulsion explosive was continuously charged throughout the hole, and digital electronic detonators were used for detonation. Bundle-shaped pillars were arranged in chambers 8 and 9 of the transport roadway at -255m. The mining area was blasted in three stages, using electronic detonators for segmented millisecond micro-delay detonation. The same row of holes was detonated in the same segment, with a detonation interval of 50ms between rows. S3: Ore handling and ventilation. The mined ore is scraped into the No. 2 pass through the N7# electric scraper funnel at the -275m level, and then transferred to the -295m middle section for loading and transportation. Fresh air enters the No. 1 foot shaft from the -295m middle section and then enters the -275m level electric scraper, while the polluted air is discharged to the surface through the No. 3 return air shaft.

2. The safe recovery method of construction for middle section pinch ore body according to claim 1, characterized in that: The construction steps of the suspended tank method are as follows: a drilling rig is arranged in the middle section at -255m to drill a central hole with a diameter of 100mm along the center of the well; a hoisting device is installed horizontally at -255m, and a steel rope is passed through the central hole and connected to the suspended tank in the middle section at -295m. After completing the rock drilling and explosive loading operations on the suspended container, the container is lowered to carry out the blasting. Slag is removed at a level of -295m, and a bottom-up construction sequence is adopted.

3. The method for safe recovery of a middle section pinched ore body according to claim 1, characterized in that: The construction sequence of the mining preparation project is as follows: first, construct the electric scraper track, electric scraper chamber, and return air duct of the No. 1 guide section in the -295m middle section; then, widen the shaft position by brushing the side walls; next, construct the hoisting chamber in the -255m middle section, using the hoisting method to construct the shaft; then, construct the N7# electric scraper chamber, electric scraper track, and funnel at the -275m level; then, construct the cutting layer and vertical trench ceiling at the -270m and -260m levels respectively; and finally, construct the No. 8 and No. 9 chambers in the -255m middle section.

4. The method for safe recovery of a middle-segment pinched ore body according to claim 1, characterized in that: The phased blasting is as follows: the first blasting involves blasting some holes in rows C1-C4 of the central holes in the No. 2 vertical trench, some holes in rows C1-C2 of the deep holes in the No. 2 vertical trench, and all holes in rows P1-P19 of the No. 8 chamber, totaling 102 holes; the second blasting involves blasting the remaining deep holes in the No. 2 vertical trench, the central holes in rows S1-S7 of the No. 3 chamber, and the deep holes in rows S1-S4, totaling 94 holes; and the third blasting involves blasting the central holes in rows N1-N11 of the No. 4 chamber, the deep holes in rows N1-N7, and all holes in rows P1-P12 of the No. 9 chamber, totaling 200 holes.

5. The method for safe recovery of a pinch-out ore body in a mid-section according to claim 1, characterized in that: The method eliminates the need for horizontal pillars and allows for the combined mining of the remaining ore around the -255m horizontal transport roadway and the structural pillars at the bottom of the N14# electric scraper roadway.

6. The method for safe recovery of a pinch-out ore body in a mid-section according to claim 1, characterized in that: Three-stage blasting: After loading explosives into all the blast holes within the first detonation range, the blasting is detonated. After a few days, some ore is extracted from the bottom first. Then, the blast holes within the second detonation range are tested, loaded with explosives, and detonated again. After another few days, some ore is extracted from the bottom, and the above operation is repeated for the third detonation. The first blasting was initiated with boreholes #1 in row C1 and #1 and #2 in row C2, which were located at depths of -270 to -260m. This initial detonation provided a passageway for the blasting of the intermediate boreholes at depths of -260 to -250m. Subsequently, some boreholes in rows C1, C2, C3, and C4 around the vertical shaft at depth of -260m were blasted. Then, the boreholes in each row of the chamber at depth of chamber #8 were blasted sequentially.

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