A method of mining by longwall top slicing

Abstract

The application provides a downward layering filling mining method, and relates to the technical field of layering filling mining. In the downward layering filling mining method, the middle sections are mined from top to bottom, and each section in the middle section is also mined from top to bottom. The ore body is divided into several middle sections, and the middle sections are arranged into sections. The section is divided into several mining fields. The boundary between the middle section and the section is a curve formed by connecting several flat bottom V-shaped structures. The middle section transport drifts and the section transport drifts are arranged outside the lower disc of the ore body vein. The middle section chute is arranged between the middle sections, and the middle section chute connects the middle section transport drifts of the upper and lower middle sections. The middle section air return drift is arranged in the upper disc of the ore body vein, and the middle section air return drift is connected with the special air return shaft. The downward layering filling method realizes automatic ore transport and ore falling, high efficiency, low cost and safe mining during downward horizontal layering filling, improves the mining capacity and reduces the mining cost, and ensures the mining safety.

Description

Technical Field

[0001] This invention relates to the field of layered backfilling mining technology, and more specifically, to a downward layered backfilling mining method. Background Technology

[0002] Currently, when backfilling and mining steeply dipping or inclined thick ore bodies, the downward horizontal layered backfilling method or the downward access backfilling method is generally used when the ore and rock are not stable enough. When using the downward horizontal layered backfilling method, it is necessary to reinforce the bottom layer of the upper layered backfill body into a solid artificial false bottom, or switch to the downward access backfilling method with smaller exposed space.

[0003] When using the downward horizontal layered backfilling method, the high cost of constructing a false bottom with reinforced steel and high-strength concrete leads to higher ore mining costs. Conversely, when using the downward access backfilling method with its limited exposed space, the restricted working face results in lower ore extraction capacity, failing to meet the requirements of large-scale ore mining. Furthermore, regardless of whether it's the downward horizontal layered backfilling or downward access backfilling method, the blasted ore is generally piled up in situ after blasting, requiring long-distance transport by loading equipment, further increasing transportation costs and reducing mining efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the above-mentioned background technology and provide a high-efficiency and low-cost downward layered filling mining method that is applicable to thick ore bodies with unstable ore rocks, does not require the construction of high-strength artificial false bottoms, has high ore extraction efficiency, and allows some ore to fall automatically.

[0005] To achieve the above objectives, the technical solution adopted by this invention is as follows: A downward layered filling mining method is provided, in which the intermediate sections are mined from top to bottom, and each sub-section within the intermediate section is also mined from top to bottom. Before formal mining, the ore body is divided into several intermediate sections according to the vertical height of each intermediate section of 40-60m, and the intermediate sections are further subdivided into sub-sections every 8-10m. Within each sub-section, several stopes are divided every 80-120m. Each stope is rectangular in plan view and has a flat-bottomed V-shaped structure with a low center and upward-sloping wings on both sides in a vertical cross-section. The width of the flat-bottomed part in the low center is about 10-12m, and the inclination angle of the two upward-sloping wings is 30-45°. The boundary between the intermediate sections and sub-sections is a curve formed by connecting several flat-bottomed V-shaped structures.

[0006] Intermediate transport horizontal tunnels and segmented transport horizontal tunnels are arranged in the hanging wall of the ore body; intermediate chutes are arranged between the intermediate sections, and the intermediate chutes connect the intermediate transport horizontal tunnels of the upper and lower intermediate sections; intermediate return air tunnels are arranged in the hanging wall of the ore body, and the intermediate return air tunnels are connected to dedicated return air shafts.

[0007] The down-layer filling mining method includes the following steps:

[0008] A: From the segmented transport tunnel, the segmented connecting tunnel is driven horizontally along the ore body to enter the flat bottom section of the V-shaped stope. The flat bottom section is about 10-12m wide. In the center of the bottom of the stope, a central tunnel is driven through the entire horizontal thickness of the ore body. The central tunnel is 3-4m wide.

[0009] B: Fill the central measures level roadway with backfill material. The backfill material partition wall is about 3-4m away from the upper and lower boundaries of the ore body. After the backfill material solidifies, enter through the segmented connecting roadway and excavate two horizontal roadways around the backfill material perpendicular to the ore body strike. Connect with the previously reserved unfilled central measures level roadway to form a central ring level roadway. The backfill material previously filled in the central measures level roadway forms a central backfill partition wall that divides the stope into left and right parts.

[0010] Then, from the end of the central annular horizontal tunnel near the footwall of the ore body, the mining ventilation and uphill access roads are excavated on the two inclined wings above the mining area. According to the dip angle of the two wings, in order to meet the needs of equipment and personnel passage, the mining ventilation and uphill access roads are arranged in a pseudo-inclined manner. After the mining ventilation and uphill access roads reach the end of the sub-mining area, the vein return air horizontal tunnel is excavated horizontally perpendicular to the strike of the ore body. From the vein return air horizontal tunnel, a short return air connecting tunnel is excavated horizontally above the footwall outside the vein. The return air connecting tunnel is then used to excavate the middle section return air shaft. The middle section return air shaft is connected to the middle section return air horizontal tunnel through a short tunnel.

[0011] C: Divide the left and right wings of the flat-bottomed V-shaped stope into several pseudo-inclined strips in an oblique direction parallel to the stope ventilation and uphill access. The width of the pseudo-inclined strips is about 12 to 16m. In the middle of the pseudo-inclined strips, pseudo-inclined strip access routes parallel to the stope ventilation and uphill access routes are arranged.

[0012] D: Strip ore-receiving pillars are left at the bottom of the two wings of the flat-bottomed V-shaped stope near the flat bottom, with a thickness of about 2-3m. During pseudo-dipping strip mining, mining is carried out from the bottom of the two wings of the flat-bottomed V-shaped stope near the central bottom, and the drilling and charging equipment enters the return airway from the stope ventilation and uphill access road, and then enters the pseudo-dipping strip access road for drilling and charging. After blasting, some of the ore rolls down to the strip ore-receiving pillars under the action of gravity. The loading equipment enters from the bottom of the two wings and loads the ore into the pseudo-dipping strip access road to the transport equipment, which transports it out of the stope to the surface. After the other ore bodies in the pseudo-dipping strip are mined, the strip ore-receiving pillars of the pseudo-dipping strip are mined last.

[0013] To improve the ore extraction capacity and ensure the safety of the stope, the pseudo-inclined strips on both wings of the flat-bottomed V-shaped stope are mined one at a time. When one pseudo-inclined strip is mined, the adjacent pseudo-inclined strips are not mined to support the roof. To further ensure the safety of mining, the opposite pseudo-inclined strips on both wings of the flat-bottomed V-shaped stope adopt a staggered mining mode.

[0014] E: After the first set of pseudo-dipping strips is mined, the empty area generated by its mining is filled; after the filling body solidifies, the adjacent pseudo-dipping strips are mined, and the mining process is as described in step D; all pseudo-dipping strips except for the strips where the stope ventilation and the uphill access road are located and the corner ore bodies are mined in an alternating manner.

[0015] F: Subsequently, mining is carried out on the strip where the stope ventilation and uphill access are located, as well as the corner ore bodies without pseudo-dipping strip access. At this time, no strip ore-receiving pillars are set up. When mining the pseudo-dipping strip where the stope ventilation and uphill access are located, mining is carried out from the upper part of both wings of the flat-bottomed V-shaped stope downwards to the central bottom. The lower ore body is used to hold back the upper blasted ore body to prevent it from falling on a large scale and to ensure mining safety. The shovel loading equipment enters the access to shovel the ore to the transportation equipment to transport it out of the stope to the surface.

[0016] G: After the mining of the strip containing the stope ventilation and the uphill access road, as well as the corner ore bodies without pseudo-inclined strip access roads, is completed, the ore bodies on top of the vein return airway, the central annular airway, and the central filling partition wall adjacent to the mined stope are mined by blasting. Then, the remaining unfilled parts of the stope are filled, and the filling order is as follows: the void area containing the corner ore bodies without pseudo-inclined strip access roads → the void area above the vein return airway → the void area containing the stope ventilation and uphill access road → the void area above the central annular airway and the central filling partition wall.

[0017] Furthermore, in step D, the central annular level tunnel can form a ring passage, improving the transportation efficiency of transport equipment in the flat-bottomed V-shaped mining area.

[0018] Furthermore, in step D, during pseudo-inclined strip mining, a shaped charge is used, with the shaped charge cavity facing the middle bottom of the flat-bottomed V-shaped stope. The ore is transported in a directional manner using explosive force to assist in achieving larger-scale automatic ore dropping by coordinating with the inclined slope of the two wings of the flat-bottomed V-shaped stope.

[0019] Furthermore, in steps D and E, when mining the pseudo-inclined strip, the strip where the stope ventilation and uphill access road are located is temporarily not mined, in order to ensure smooth ventilation in the stope and that personnel and equipment can smoothly enter the two wings of the V-shaped stope.

[0020] Furthermore, in step G, when mining and filling the return airway and the upper void area within the vein, only the portion adjacent to the already mined stope is mined and filled; while the return airway adjacent to the unmined stope is not mined for the time being, so as to be used for ventilation and pedestrian access when the next stope is mined.

[0021] Furthermore, the strip filling is carried out in layers, with a single layer filling height of 2 to 3 meters; when filling the top layer, phenolic resin foam material is used to fill in order to meet the requirements of the filling body to the top.

[0022] Furthermore, the phenolic resin foam material is formed by reacting component A and component B in a volume ratio of 4:1. Component A is composed of phenolic resin and foaming agent in a mass ratio of 4:1, and component B is composed of organic acid and inorganic acid in a mass ratio of 7:3.

[0023] Compared with the prior art, the downward layered filling method of the present invention has the following advantages:

[0024] 1) The downward layered filling method divides the ore body in the stope into two wings, and the two wings are divided into pseudo-dipping strips. The strips have pseudo-dipping strip access routes, which can be mined simultaneously by multiple strip access routes. Compared with the general downward horizontal layered filling mining method, the ore production capacity of the stope has been greatly improved.

[0025] 2) Compared with the general downward horizontal layered filling mining method, the downward layered filling method of this invention has a flat-bottomed V-shaped structure stope with a flat bottom in the middle and two wings inclined at 30-45°. The flat bottom in the middle of the stope is a central annular horizontal roadway, which is separated by a central filling partition wall. The transportation equipment can achieve circular transportation without the need for passing and shunting, resulting in higher ore loading and transportation efficiency. When mining the inclined wings, some ore can automatically roll down, saving ore transfer costs.

[0026] 3) When mining the two wings of a flat-bottomed V-shaped stope, the ore body on both wings is divided into several pseudo-inclined strips along an oblique direction parallel to the stope ventilation and uphill access. During mining, the pseudo-inclined strips on both wings of the flat-bottomed V-shaped stope are mined alternately, and the pseudo-inclined strips on both wings are mined in a staggered mining mode. The unmined pseudo-inclined strips can effectively support the roof. Furthermore, since the roof filling is also inclined, the pressure from above on the flat-bottomed V-shaped stope is further dispersed, and the stress on the stope is reduced. Therefore, the upper filling of the downward layered filling method of this invention does not require the production of a high-cost, high-strength artificial false bottom to ensure mining safety.

[0027] 4) When mining the two wings of the flat-bottomed V-shaped stope, the inclination angle of the two wings is relatively large. In addition, the use of shaped charge explosives for blasting operations, and controlling the shaped charge explosives to be oriented towards the middle bottom of the flat-bottomed V-shaped stope, enables the directional transport of a large amount of ore by explosive force and automatic ore dropping, which can effectively reduce the ore transfer distance and transfer cost. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a front view of the mining process according to an embodiment of the present invention.

[0030] Figure 2 This is a top view of the mining process in an embodiment of the present invention.

[0031] Figure 3 This is a schematic diagram of step A of mining in a single mining area according to an embodiment of the present invention.

[0032] Figure 4 This is a schematic diagram of step B of mining in a single mining area according to an embodiment of the present invention.

[0033] Figure 5 This is a schematic diagram of step C of mining in a single mining area according to an embodiment of the present invention.

[0034] Figure 6 This is a schematic diagram of step D of mining in a single mining area according to an embodiment of the present invention.

[0035] Figure 7 This is a schematic diagram of step E of mining in a single mining area according to an embodiment of the present invention.

[0036] Figure 8 This is a schematic diagram of step F of mining in a single mining area according to an embodiment of the present invention.

[0037] Figure 9 This is a schematic diagram of step G of mining in a single mining area according to an embodiment of the present invention.

[0038] Explanation of symbols in the diagram:

[0039] 1. Intermediate haulage level; 2. Segmented haulage level; 3. Intermediate chute; 4. Segmented connecting roadway; 5. Central access level; 6. Central filling partition wall; 7. Intermediate ring level; 8. Stope ventilation and uphill access road; 9. Intravesical return air level; 10. Return air connecting roadway; 11. Intermediate return air shaft; 12. Intermediate return air level; 13. Dedicated return air shaft; 14. Pseudo-inclined strip; 15. Pseudo-inclined strip access road; 16. Strip ore-receiving pillar; 17. Temporary access road at the corner of the stope. Detailed Implementation

[0040] To make the technical problems, solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0041] The downward layered filling mining method provided by the embodiments of the present invention will now be described. For example... Figure 1 , Figure 2 As shown, this embodiment is for mining steeply dipping thick ore bodies, and adopts the downward layered filling mining method. The middle section is mined from top to bottom, and each sub-section within the middle section is mined from bottom to top.

[0042] Before formal mining, the ore body is divided into several intermediate sections with a vertical height of 40-60m. These intermediate sections are then further subdivided into segments every 8-10m. Within each segment, several stopes are divided every 80-120m. Each stope is rectangular in plan view and, vertically along the strike, has a flat-bottomed V-shaped structure with a lower center and upward-sloping wings. The width of the lower flat-bottomed portion of the stope is approximately 10-12m, and the dip angle of the two upward-sloping wings is 30-45°. The boundaries between intermediate sections and segments are curves formed by connecting several flat-bottomed V-shaped structures.

[0043] like Figure 1 , Figure 2 As shown, a mid-section transport level 1 and a segmented transport level 2 are arranged on the lower footwall outside the ore body. A mid-section chute 3 is arranged between the mid-sections, and the mid-section chute 3 connects the mid-section transport level 1 of the upper and lower mid-sections. A mid-section return air level 12 is arranged on the upper footwall outside the ore body, and the mid-section return air level 12 is connected to a dedicated return air shaft 13.

[0044] like Figures 3-9 As shown, the formal mining of a single stope includes steps A through G:

[0045] A: From the segmented transport level 2, the segmented connecting roadway 4 is driven horizontally perpendicular to the ore body to enter the flat bottom section of the V-shaped stope, which is about 10-12m wide. A central measures level 5, 3-4m wide, is then driven through the center of the stope bottom, penetrating the entire horizontal thickness of the ore body.

[0046] B: Fill the central measures level roadway 5 with backfill material, with the backfill partition wall about 3-4m away from the boundaries of the hanging wall and footwall of the ore body. After the backfill material solidifies, it enters through the segmented connecting roadway 4 and is driven into two horizontal roadways perpendicular to the ore body strike around the backfill material. These roadways connect with the previously reserved unfilled central measures level roadway 5 to form the central annular level roadway 7. The backfill material previously filled in the central measures level roadway 5 forms the central backfill partition wall 6 that divides the stope into left and right parts.

[0047] Then, from the end of the central annular horizontal tunnel 7 near the footwall of the ore body, the two inclined wings of the stope are excavated to form the stope ventilation and uphill access roads 8. According to the dip angle of the two wings, in order to meet the needs of equipment and personnel passage, the stope ventilation and uphill access roads 8 are arranged in a pseudo-inclined manner. After the stope ventilation and uphill access roads 8 reach the end of the sub-stope, the vein return air horizontal tunnel 9 is excavated horizontally perpendicular to the strike of the ore body. From the vein return air horizontal tunnel 9, a short return air connecting tunnel 10 is excavated horizontally to the footwall outside the vein. From the return air connecting tunnel 10, the middle section return air shaft 11 is excavated upwards. The middle section return air shaft 11 is connected to the middle section return air horizontal tunnel 12 through a short tunnel.

[0048] C: Divide the left and right wings of the flat-bottomed V-shaped stope into several pseudo-inclined strips 14 in an oblique direction parallel to the stope ventilation and uphill access road 8. The pseudo-inclined strips 14 are about 12 to 16 m wide. In the middle of the pseudo-inclined strips 14, pseudo-inclined strip access roads 15 are arranged parallel to the stope ventilation and uphill access road 8.

[0049] D: Strip-shaped ore-receiving pillars 16 are left near the bottom of the flat-bottomed V-shaped stope on both wings, with a thickness of approximately 2-3 meters. During the mining of the pseudo-dipping strip 14, mining proceeds diagonally upwards from near the central bottom of both wings of the flat-bottomed V-shaped stope. The drilling and charging equipment enters the vein's return airway 9 from the stope ventilation and uphill access road 8, and then enters the pseudo-dipping strip access road 15 for drilling and charging. After blasting, some of the ore rolls down to the strip-shaped ore-receiving pillars 16 under gravity. Loading equipment enters from the bottom of both wings into the pseudo-dipping strip access road 15 to load the ore onto the transport equipment, which then transports it out of the stope to the surface. After the other ore bodies in the pseudo-dipping strip 14 have been mined, the strip-shaped ore-receiving pillars 16 of the pseudo-dipping strip 14 are mined last.

[0050] To improve ore extraction capacity and ensure safety in the stope, the pseudo-inclined strips 14 on both wings of the flat-bottomed V-shaped stope are mined alternately. When one pseudo-inclined strip 14 is being mined, the adjacent pseudo-inclined strips 14 are not mined to support the roof. To further ensure mining safety, the opposite pseudo-inclined strips 14 on both wings of the flat-bottomed V-shaped stope are mined in a staggered manner.

[0051] E: After the first set of pseudo-dipping strips 14 is mined, the resulting voids are filled. After the filling material solidifies, the adjacent pseudo-dipping strips 14 are mined, following the process described in step D. All pseudo-dipping strips 14, excluding the strip containing the stope ventilation and uphill access road 8, and the corner ore bodies, are mined in an alternating manner.

[0052] F: Subsequently, mining will proceed along the strip containing the stope ventilation and uphill access road 8, as well as the corner ore bodies of access road 15 without pseudo-dipping strips. At this stage, no strip-receiving pillars 16 will be installed. During the mining of the pseudo-dipping strip 14 containing the stope ventilation and uphill access road 8, mining will proceed downwards from the upper part of both wings of the flat-bottomed V-shaped stope towards the central bottom. The lower ore body will hold back the upper blasted ore body, preventing it from falling on a large scale and ensuring mining safety. Loading equipment will enter the stope ventilation and uphill access road 8 to load ore into transport equipment, which will then transport it out of the stope to the surface.

[0053] G: After the mining of the ore body in the strip containing the stope ventilation and uphill access road 8, and the corner ore body of the access road 15 without pseudo-inclination strip, the ore body at the top of the vein return airway 9, the central annular airway 7, and the central filling partition wall 6 adjacent to the mined stope will be mined by blasting. Then, the remaining unfilled parts of the stope will be filled in the following order: the empty area where the corner ore body of the access road 15 without pseudo-inclination strip is located → the empty area of ​​the vein return airway 9 and its upper part → the empty area of ​​the strip containing the stope ventilation and uphill access road 8 → the empty area of ​​the central annular airway 7 and the central filling partition wall 6 and its upper part.

[0054] In step D, the central annular level roadway 7 can form an annular passage, improving the transportation efficiency of the transport equipment in the flat-bottomed V-shaped stope. When the pseudo-inclined strip 14 is mined, in conjunction with the shaped charge technology, the shaped charge cavity of the charge is oriented towards the middle bottom of the flat-bottomed V-shaped stope, and the blasting directionally transports the ore to assist in achieving a larger-scale automatic ore dropping by coordinating with the inclined slope of the two wings of the flat-bottomed V-shaped stope.

[0055] In steps D and E, when mining the pseudo-inclined strip 14, the strip where the stope ventilation and uphill access road 8 are located will not be mined for the time being, in order to ensure smooth ventilation in the stope and that personnel and equipment can smoothly enter the two wings of the V-shaped stope.

[0056] In step G, when mining and filling the return airway 9 and the upper void area within the vein, only the portion adjacent to the already mined stope is mined and filled; the return airway 9 adjacent to the unmined stope is not mined for the time being, so as to be used as the return airway 9 for the next stope.

[0057] Furthermore, in this mining method, the pseudo-inclined strip 14 is filled in layers, with each layer having a height of 2-3 meters. For the uppermost layer, to ensure proper roof contact, phenolic resin foam is used. This foam is composed of component A and component B reacted in a 4:1 volume ratio. Component A is a mixture of phenolic resin and a foaming agent in a 4:1 mass ratio, while component B is a mixture of organic and inorganic acids in a 7:3 mass ratio. After filling, this foam can expand more than 25 times its volume while maintaining sufficient support strength, thus ensuring good roof contact for the filling. This foam is suitable for both non-coal underground mines and coal mines.

[0058] This invention proposes a downward layered backfilling mining method for mining steeply dipping or inclined thick ore bodies, where some ore from the stopes can be automatically removed. This method solves the problems of high costs associated with constructing high-strength artificial false bottoms in traditional downward horizontal layered backfilling mining of steeply dipping or inclined thick ore bodies, and the low production capacity of downward-entry backfilling methods. The downward layered backfilling mining method of this invention achieves automatic ore removal and high-efficiency, low-cost, and safe mining during downward horizontal layered backfilling through the design of irregular layering, flat-bottomed V-shaped stope structures, and the division of pseudo-dipping strips on both sides of the stope. This improves mining capacity, reduces mining costs, and ensures mining safety.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Those skilled in the art can make various modifications and variations to the embodiments of the present invention. If these modifications and variations fall within the scope of the claims of the present invention and their equivalents, then these modifications and variations are also within the protection scope of the present invention. Content not described in detail in the specification is prior art known to those skilled in the art.

Claims

1. A method of mining by longwall top slicing, characterised in that: In the downward layered filling mining method, the intermediate sections are mined from top to bottom, while the sub-sections within each intermediate section are mined from bottom to top. Before formal mining, the ore body is divided into several intermediate sections according to the vertical height of each intermediate section of 40-60m. Each intermediate section is further divided into sub-sections every 8-10m. Within each sub-section, several stopes are divided every 80-120m. A single stope is rectangular in plan view and has a flat-bottomed V-shaped structure with a lower middle section and upward sloping wings on both sides. The width of the flat bottom section in the middle is 10-12m, and the dip angle of the two upward sloping wings is 30-45°. The boundary between intermediate sections and sub-sections is a curve formed by connecting several flat-bottomed V-shaped structures. Intermediate transport horizontal tunnels and segmented transport horizontal tunnels are arranged in the hanging wall outside the ore body; intermediate chutes are arranged between the intermediate sections, and the intermediate chutes connect the intermediate transport horizontal tunnels of the upper and lower intermediate sections; intermediate return air tunnels are arranged in the hanging wall outside the ore body, and the intermediate return air tunnels are connected to dedicated return air shafts. The down-filling mining method includes the following steps: A: From the segmented transport tunnel, the segmented connecting tunnel is driven horizontally along the ore body to enter the flat bottom section of the V-shaped stope. The flat bottom section is 10-12m wide. In the center of the bottom of the stope, a central measures tunnel is driven through the entire horizontal thickness of the ore body. The central measures tunnel is 3-4m wide. B: Fill the central measures level roadway with backfill material. The backfill material partition wall is 3-4m away from the upper and lower boundaries of the ore body. After the backfill material solidifies, enter through the segmented connecting roadway and excavate two horizontal roadways around the backfill material perpendicular to the ore body strike. Connect with the previously reserved unfilled central measures level roadway to form a central ring level roadway. The backfill material previously filled in the central measures level roadway forms a central backfill partition wall that divides the stope into left and right parts. Then, from the end of the central annular horizontal tunnel near the footwall of the ore body, the mining ventilation and uphill access roads are excavated on the two inclined wings above the mining area. According to the dip angle of the two wings, in order to meet the needs of equipment and personnel passage, the mining ventilation and uphill access roads are arranged in a pseudo-inclined manner. After the mining ventilation and uphill access roads reach the end of the sub-mining area, the vein return air horizontal tunnel is excavated horizontally perpendicular to the strike of the ore body. From the vein return air horizontal tunnel, a short return air connecting tunnel is excavated horizontally above the footwall outside the vein. The return air connecting tunnel is then used to excavate the middle section return air shaft. The middle section return air shaft is connected to the middle section return air horizontal tunnel through a short tunnel. C: Divide the left and right wings of the flat-bottomed V-shaped stope into several pseudo-inclined strips in an oblique direction parallel to the stope ventilation and uphill access. The width of the pseudo-inclined strips is 12-16m. In the middle of the pseudo-inclined strips, pseudo-inclined strip access routes parallel to the stope ventilation and uphill access routes are arranged. D: Strip ore-receiving pillars are left near the bottom of the flat bottom V-shaped stope on both wings, with a thickness of 2-3m. During pseudo-dipping strip mining, mining is carried out from the bottom of the flat bottom V-shaped stope on both wings, diagonally upwards. After the rock drilling and charging equipment enters the return airway from the stope ventilation and uphill access road, it enters the pseudo-dipping strip access road for rock drilling and charging. After blasting, some of the ore rolls down to the strip ore-receiving pillars under the action of gravity. The shoveling equipment enters the pseudo-dipping strip access road from the bottom of both wings to shovel the ore to the transport equipment, which transports it out of the stope to the surface. After the other ore bodies in the pseudo-dipping strip are mined, the strip ore-receiving pillars of the pseudo-dipping strip are mined last. To improve the ore extraction capacity and ensure the safety of the stope, the pseudo-inclined strips on both wings of the flat-bottomed V-shaped stope are mined one at a time. When one pseudo-inclined strip is mined, the adjacent pseudo-inclined strips are not mined to support the roof. To further ensure the safety of mining, the opposite pseudo-inclined strips on both wings of the flat-bottomed V-shaped stope adopt a staggered mining mode. E: After the first set of pseudo-dipping strips is mined, the empty area generated by its mining is filled; after the filling body solidifies, the adjacent pseudo-dipping strips are mined, and the mining process is as described in step D; all pseudo-dipping strips except for the strips where the stope ventilation and the uphill access road are located and the corner ore bodies are mined in an alternating manner. F: Subsequently, mining is carried out on the strip where the stope ventilation and uphill access are located, as well as the corner ore bodies without pseudo-dipping strip access. At this time, no strip ore-receiving pillars are set up. When mining the pseudo-dipping strip where the stope ventilation and uphill access are located, mining is carried out from the upper part of both wings of the flat-bottomed V-shaped stope downwards to the central bottom. The lower ore body is used to hold back the upper blasted ore body to prevent it from falling on a large scale and to ensure mining safety. The shovel loading equipment enters the access to shovel the ore to the transportation equipment to transport it out of the stope to the surface. G: After the mining of the strip containing the stope ventilation and the uphill access road, as well as the corner ore bodies without pseudo-inclined strip access roads, is completed, the ore bodies on top of the vein return airway, the central annular airway, and the central filling partition wall adjacent to the mined stope are mined by blasting. Then, the remaining unfilled parts of the stope are filled, and the filling order is as follows: the void area containing the corner ore bodies without pseudo-inclined strip access roads → the void area above the vein return airway → the void area containing the stope ventilation and uphill access road → the void area above the central annular airway and the central filling partition wall.

2. The downward layered backfilling mining method as described in claim 1, characterized in that: In step D, the central annular level tunnel forms a ring passage, improving the transportation efficiency of transport equipment in the flat-bottomed V-shaped mining area.

3. The downward layered backfilling mining method as described in claim 1, characterized in that: In step D, during pseudo-inclined strip mining, a shaped charge is used with the shaped charge cavity facing the middle bottom of the flat-bottomed V-shaped stope. The ore is transported by explosive force in a directional manner to assist in achieving a larger-scale automatic ore dropping by cooperating with the inclined slope of the two wings of the flat-bottomed V-shaped stope.

4. The downward layered backfilling mining method as described in claim 1, 2, or 3, characterized in that: In steps D and E, when mining the pseudo-inclined strip, the strip where the stope ventilation and uphill access road are located will not be mined temporarily, in order to ensure smooth ventilation in the stope and that personnel and equipment can smoothly enter the two wings of the V-shaped stope.

5. The downward layered backfilling mining method as described in claim 1, characterized in that: In step G, when mining and filling the return airway and its upper void within the vein, only the portion adjacent to the already mined stope is mined and filled. The return airway adjacent to the unmined stope will not be mined for the time being, in order to be used for ventilation and pedestrian access during the next stope mining.

6. The downward layered backfilling mining method as described in claim 1, characterized in that: When filling strips, layered filling is adopted, with a single layer filling height of 2-3m; when filling the top layer, phenolic resin foam material is used to fill in order to meet the need for the filling body to reach the top.

7. The downward layered backfilling mining method as described in claim 6, characterized in that: The phenolic resin foam material is formed by reacting component A and component B in a volume ratio of 4:

1. Component A is composed of phenolic resin and foaming agent in a mass ratio of 4:1, and component B is composed of organic acid and inorganic acid in a mass ratio of 7:3.

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