A framework stoping method suitable for underground ore bodies in extreme geological conditions

Abstract

This invention relates to the field of underground metal deposit mining technology, and discloses a frame-type backfill mining method suitable for underground deposits under extreme geological conditions. The top of the ore block is reconstructed using a downward approach, first mining the stope, then the pillars. Deep-hole grouting is used to plug water in the footwall's water-rich layer, and the surrounding rock of the pillar's hanging wall is reinforced by grouting to create hydrological and engineering geological safety conditions. The lower stope is mined using a downward approach backfilling method. The pillars, protected by surrounding backfill, are mined using a staged drilling method followed by backfilling. Finally, a one-step stope pillar recovery is performed using medium-deep holes. After the stope and pillars are mined, downsloping backfilling boreholes are drilled to the goaf for backfilling. This method solves the problems of existing technologies, such as the lack of coupling of water control and soft ore body mining, small stope parameters, and low production capacity. It effectively controls risks such as water inrush and roof collapse, improves mining safety and efficiency, and achieves safe and efficient mining of underground deposits under extreme geological conditions.

Description

Technical Field

[0001] This invention relates to the field of underground metal deposit mining technology, specifically a frame-type backfilling mining method suitable for underground deposits under extreme geological conditions. Background Technology

[0002] Large-scale water-bearing, soft-rock-bearing, and fractured mines are among the most complex, risky, technically challenging, and costly types of mines, posing the most severe challenge to safe production in underground metal mines. These mines are characterized by massive water inflows, fractured ore and rock, and poor mechanical properties. When a mine simultaneously possesses these three characteristics—large water volume, soft rock, and fractured rock—it faces risks such as water inrush, roof collapse, and spalling, significantly increasing the difficulty of mining. Furthermore, these factors can interact and exacerbate each other.

[0003] Previous studies have mainly focused on safety protection for weak and fractured ore bodies through pre-controlled roof support, false roof / bottom construction of backfill bodies, and grouting reinforcement of rock masses. A series of mining methods have been developed. For example, CN119163410A discloses a combined segmented backfilling mining method for steeply inclined, relatively fractured, thick, and large-scale ore bodies. The ore body is divided into segments according to its location in the middle section, with each middle section further divided into upper, middle, and lower segments. Panels are divided along the strike of the ore body, and within each panel, the ore blocks are divided into upper and lower mining areas. The upper mining area is divided into several first-step stops and second-step pillars, and is mined using the segmented open stope followed by backfilling mining method. The lower mining area is divided into several access stopes, and is mined using the pre-controlled roof access backfilling mining method. The stope height in the lower mining area is the lower segment height, and the stope height in the upper mining area is the upper and middle segment heights.

[0004] However, existing technologies only target fractured ore bodies, failing to consider the large water environment of the deposit and thus failing to couple mine water control with the mining of soft and fractured ore bodies. Furthermore, the mining methods provided by existing technologies are all small-parameter stopes, with low production capacity and high production costs, making it difficult to achieve safe and efficient mining of underground deposits under extreme geological conditions of large water and soft fractures. Summary of the Invention

[0005] The purpose of this invention is to provide a frame-type backfill mining method suitable for underground deposits under extreme geological conditions. The top of the ore block is reconstructed using a downward approach, first mining the stope, then the pillars. Deep-hole grouting is used to plug water in the footwall's water-rich layer, and grouting is also used to reinforce the surrounding rock of the pillar's hanging wall, creating hydrological and engineering geological safety conditions. The lower stope is mined using a downward approach backfilling method. The pillars, protected by surrounding backfill, are mined using a staged drilling method followed by backfilling. Finally, a one-step stope pillar recovery is performed using medium-deep holes. After the stope and pillars are mined, downsloping backfilling boreholes are drilled to the goaf for backfilling. This method effectively prevents risks such as water inrush and roof collapse, improves mining safety and efficiency, and enables safe and efficient mining of underground deposits under extreme geological conditions, solving the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A frame-type backfill mining method suitable for underground deposits under extreme geological conditions, characterized by comprising the following steps:

[0008] Step 1: Using ore blocks as production units, the ore blocks are arranged perpendicular to the strike of the ore body, and all development and preparation works are arranged on the side away from the water-rich rock group.

[0009] Step 2: Use deep hole grouting to plug water in the footwall of the ore body and reinforce the surrounding rock of the hanging wall in the second-step pillar mining area;

[0010] Step 3: The top mining area of ​​the ore block is mined using the downward approach cemented backfilling method. After the approach mining is completed, high-strength cemented backfilling is carried out to form an artificial roof for the lower mining area.

[0011] Step 4: First, mine the stope in the first part of the area. The stope is mined using the down-entry backfilling method. After the down-entry backfilling is completed, cemented backfilling is carried out immediately. The ore body of the lowest segment of the stope is left as a bottom pillar and is not mined for the time being.

[0012] Step 5: After the stope is backfilled, the second-stage pillar is backfilled using the segmented drilling stage followed by backfilling method.

[0013] Step 6: After the pillar is mined out, drill a downward-sloping filling borehole to the goaf, lay filling pipes for staged filling and roof connection.

[0014] After step seven and two, the pillars are backfilled, and the bottom pillars of the mining chamber are mined. After the mining is completed, backfilling boreholes are drilled to fill the goaf.

[0015] Preferably, in step one, the length of the ore block along the strike is 50.0m-60.0m, the width perpendicular to the strike is equal to the thickness of the ore body, and the height is 50.0-60.0m; the middle section is divided into several segments with a height of 12.0-15.0m, and the height of the first mining area at the top of the ore block is 7.0-8.0m; the width of the stope and the pillars are both 12.0-15.0m, and they are all arranged perpendicular to the strike of the ore body.

[0016] Preferably, in step two, the opening diameter of the grouting hole is 108mm, and the final hole diameter is 75mm; the hole opening uses a seamless steel pipe with an outer diameter of 89mm, a wall thickness of 3mm, and a length of 5m as the hole opening pipe, and the burial depth is not less than 4.5m; the upper grouting uses ultrafine cement-water glass single-liquid grout with a water-cement ratio of 0.8-1.0 and the amount of water glass added is 3-5% of the cement mass; the lower grouting uses silicate cement-water glass double-liquid grout with a water-cement ratio of 0.8-1.0 and the mass ratio of water glass to cement is 1:1; the thickness of the water-proof curtain layer and the surrounding rock reinforcement layer formed by grouting is not less than 20.0m.

[0017] Preferably, in step three, the top mining access road is arranged in two layers along the strike of the ore body, and each layer adopts a mining sequence of three mining passes per layer, advancing from the footwall to the hanging wall; after the access road is mined, steel bars are laid at the bottom and high-strength tailings are cemented and backfilled, with the backfill strength ≥4.0MPa; after the top mining access road of the uppermost layer is excavated, the roof is supported by a combination of anchor bolts, anchor cables, steel mesh and shotcrete.

[0018] Preferably, in step four, the stope adopts a mining sequence of one mining pass per turn, with the mining pass arranged perpendicular to the strike of the ore body, and the mining proceeds from the hanging wall to the footwall in an alternating mining sequence; after the mining pass is completed, steel bars are laid at the bottom and high-strength tailings are cemented and backfilled, with the backfill strength ≥3.0MPa; after the mining of the upper layer is completed, the next layer is mined.

[0019] Preferably, in step five, the second-step pillar adopts a mining sequence of three miners per step, advancing from the lower plate to the upper plate, with the upper section mining preceding the lower section; after the ore falls, it is removed through the bottom trench in conjunction with a loader.

[0020] Preferably, in step six, the diameter of the filling borehole is 180-220mm, and the filling pipe is a wear-resistant flexible hose; the bottom 10m of the goaf is filled with high-strength filling with a filling body strength ≥3.0MPa, and the middle and upper parts are filled with low-strength filling with a filling body strength ≥1.0MPa.

[0021] Preferably, in step seven, after the bottom pillars of the stope are mined out, medium-strength backfilling is used, with a backfill strength ≥2.0MPa; underground waste rock can be dumped to the goaf through segmented rock-drilling connecting tunnels for auxiliary backfilling.

[0022] Preferably, the ventilation system is configured as follows:

[0023] During top mining operations, fresh air enters the working face through the stratified connecting roadway and the stratified cutting cross passage, while contaminated air returns through the filling return air shaft and the filling return air cross passage. During stope mining operations, fresh air enters the working face through the stratified connecting roadway and the stratified cutting cross passage, while contaminated air returns to the upper and middle sections through the along-path filling return air shaft. During two-stage pillar mining operations, fresh air enters the working face through the middle section intake air shaft and the inclined ramp, while contaminated air returns to the upper and middle sections through the middle section return air shaft.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1. This invention achieves stope roof reconstruction through down-path mining and backfilling. Secondly, a reinforcement layer ≥20m thick is formed on the hanging wall of the second-stage pillar through deep-hole grouting. The first-stage stope is then mined using a down-path approach. Through backfilling structure reconstruction and rock mass grouting reinforcement reconstruction, a comprehensive safety protection structure is provided for high-parameter mining of the second-stage pillar. During the second-stage pillar mining, both sides and the roof are filled with high-strength backfill material, completely eliminating the risk of rock mass collapse.

[0026] 2. This invention forms a water-resistant curtain ≥20m thick in the footwall of the ore body through deep-hole grouting; the segmented drilling tunnels and bottom trenches also serve drainage functions, allowing residual water in the ore body to be drained in advance. Mining operations are arranged on another side of the water-rich stratum, avoiding the need for excavation within the water-rich stratum. Simultaneously, the softening effect of water on the ore and rock is reduced, increasing the overall strength of the ore and rock, meeting the safe mining water environment requirements of water-rich deposits, and completely isolating the risk of water inrush from the water-rich stratum.

[0027] 3. In this invention, the approach mine adopts a three-mining-one-mining or one-mining-one-mining sequence, and the stope and pillars also adopt a three-mining-one-mining sequence, significantly reducing stress concentration in the surrounding rock around the stope. During approach mining, personnel and equipment operate under the protection of a false roof, and the second-stage pillars are mined under the protection of high-strength backfill on both sides. Personnel and equipment do not enter the goaf area. Trackless equipment is used for production tunneling, rock drilling, and ore extraction, resulting in high mining safety.

[0028] 4. In this invention, after the top of the ore block and the first-stage stope are reconstructed using the approach method, the second-stage pillars and the bottom pillars of the first-stage stope both adopt upward fan-shaped medium-deep hole ore extraction, which reduces the amount of false roof construction and shortens the cycle operation time of filling, ventilation, ore extraction, and filling, thereby improving the overall production capacity of the ore block; the tunneling, rock drilling, and ore extraction all adopt trackless equipment, and the equipment can be conveniently transported through inclined ramps and segmented horizontal roadways, resulting in high shift efficiency; the second-stage pillars and the bottom pillars of the first-stage stope both adopt upward fan-shaped medium-deep hole ore extraction, which reduces the amount of false roof construction and significantly reduces the costs of rock drilling, blasting, filling, support, and mining. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the mining structure during the top mining reconstruction of the mine stope according to the present invention;

[0030] Figure 2 This is a schematic diagram of the mining structure during the first step of the mine recovery and reconstruction of the present invention;

[0031] Figure 3 This is a schematic diagram of the mining structure during the two-step pillar recovery process of the present invention;

[0032] Figure 4 for Figure 1 Schematic diagram of the IV-IV longitudinal section;

[0033] Figure 5 for Figure 1 A schematic diagram of the V-V cross-section;

[0034] Figure 6 for Figure 2 Schematic diagram of the longitudinal section of VI-VI;

[0035] Figure 7 for Figure 2 Schematic diagram of the cross section of VII-VII;

[0036] Figure 8 for Figure 3 Schematic diagram of the longitudinal section of VIII-VIII;

[0037] Figure 9 for Figure 3 Schematic diagram of the cross section of IX-IX;

[0038] Figure 10 This is a schematic diagram of a two-step pillar filling method;

[0039] Figure 11 This is a schematic diagram of a one-step filling method for the bottom of a mine.

[0040] In the diagram: 1. Mid-section transport level roadway; 2. Inclined ramp; 3. Segmented along-vein level roadway; 4. Segmented drilling roadway; 5. Mining access roadway; 501. Top mining access roadway; 502. First-stage stope mining access roadway; 6. First-stage stope pillar; 7. Layered connecting roadway; 8. Layered cutting cross roadway; 9. Layered cutting through vein; 10. Ore extraction access roadway; 11. Ore extraction access roadway connecting roadway; 12. Filling return air through vein; 13. Segmented drilling connecting roadway; 14. Mid-section intake air shaft; 15. Mid-section return air shaft; 16. Filling return air shaft; 17. Along-path filling return air shaft; 18. Filling borehole; 19. Passage; 20. Lower footing water plugging grouting hole; 21. Upper footing reinforcement grouting hole; 22. Cutting riser; 23. Medium-deep hole. Detailed Implementation

[0041] 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.

[0042] To address the issues of existing technologies lacking integration of water control and soft ore body mining, limited stope parameters, and low production capacity, please refer to [the relevant documentation / reference]. Figure 1-11 This embodiment provides the following technical solution:

[0043] The mining structure consists of six parts: basic development works, preparation works, cutting works, grouting and protection works, mining access structure, and backfilling structure.

[0044] The basic development works include the middle section transport level roadway 1 and the ramp road 2.

[0045] Specifically, the intermediate transport level 1 and the inclined ramp 2 are both located on the side away from the water-rich rock formation. If the footwall of the ore body is a water-rich rock formation, they are located on the hanging wall, and vice versa. The intermediate transport level 1 is arranged along the strike of the ore body, and the inclined ramp 2 serves as a vertical connecting channel, connecting with each intermediate transport level 1 and the segmental along-vein level 3, thereby enabling the transfer of trackless equipment between different intermediate sections and segments.

[0046] The preparation works include 3 segmented horizontal tunnels along the vein, 4 segmented rock drilling tunnels, 7 layered connecting tunnels, 10 ore exit access road, 11 ore exit access connecting tunnel, 12 filling return air passage, 13 segmented rock drilling connecting tunnel, 14 intermediate section intake air shaft, 15 intermediate section return air shaft, 16 filling return air shaft, 17 along the route filling return air shaft, and 19 ore pass.

[0047] Specifically, the segmented vein-side horizontal tunnel 3 is arranged along the strike of the ore body and connected to the inclined ramp 2; the segmented rock drilling tunnel 4 is perpendicular to the strike of the ore body and is arranged in the center of the second-stage pillar, and is connected to the segmented vein-side horizontal tunnel 3 through the segmented rock drilling connecting tunnel 13; the layered connecting tunnel 7 is perpendicular to the strike of the ore body and connects the segmented vein-side horizontal tunnel 3 with the top mining access road 501 and the first-stage stope mining access road 502 in each layer.

[0048] Specifically, the ore access roadway 11 is located at the bottom of each mining section, perpendicular to the ore body strike and in the center of the stope. The ore access roadway 10 is excavated from the ore access roadway 11 to the left and right sides at a 45° angle. The filling return air passageway 12 is located in the upper-middle section, perpendicular to the ore body strike and connected to the upper-middle section transport passageway 1. The middle section intake air shaft 14 and the middle section return air shaft 15 are both vertical shafts, connecting the upper and lower middle section transport passageways 1 and each segmental vein passageway 3. Their functions can be converted to each other as the production area changes. The filling return air shaft 16 is set in the mining area corresponding to the top two layers of access roads. The along-road filling return air shaft 17 is arranged on the hanging wall of the first-step stope. The ore pass 19 is set on one side of the middle section transport passageway 1 and connected to the lower-middle section transport passageway 1.

[0049] The cutting project includes cutting the transverse tunnel 8 in layers, cutting the through vein 9 in layers, and cutting the skylight 22.

[0050] Specifically, the layered cutting cross passage 8 is located at the boundary of the upper plate of each mining layer in the first-stage stope and is arranged along the strike of the ore body. It is connected to the segmented vein level passage 3 through the layered connecting passage 7. The layered cutting through vein 9 is perpendicular to the strike of the ore body and is arranged in the center of the top layer of the ore block. The cutting riser 22 is set in the center of the lower end of the second-stage pillar and is constructed using a reverse drilling rig to provide compensation space for the blasting of the medium-deep hole 23.

[0051] The grouting protection project includes the lower water-blocking grouting hole 20 and the upper reinforcement grouting hole 21.

[0052] Specifically, the lower footwall grouting hole 20 is drilled in the footwall surrounding rock of the ore body, while the upper footwall reinforcement grouting hole 21 is drilled only in the upper footwall surrounding rock of the second-stage pillar mining area. The two form a water-blocking curtain layer and a surrounding rock reinforcement layer with a thickness of not less than 20.0m, respectively. The opening diameter of both types of grouting holes is φ108mm, and the final hole diameter is φ75mm. The hole opening is made of seamless steel pipe with a diameter of φ89mm, a wall thickness of 3mm, and a length of 5m, and the burial depth is not less than 4.5m.

[0053] The mining access structure is arranged based on the block unit. The block is set perpendicular to the strike of the ore body, with a length of 50.0-60.0m along the strike, a width equal to the thickness of the ore body, and a height of 50.0-60.0m (the height of the middle section). The middle section is divided into several segments with a height of 12.0-15.0m. The top 7.0-8.0m of the block is the first mining area, and the lower part is divided into stopes and pillars, each with a width of 12.0-15.0m. The top mining access 501 is arranged in two layers along the strike of the ore body, with its long axis perpendicular to the long axis of the first-stage stope mining access 502 and the second-stage pillars. The first-stage stope mining access 502 is arranged perpendicular to the strike of the ore body, and the ore body of the lowest segment of the stope is retained as the first-stage stope bottom pillar 6. The second-stage pillar area is equipped with a bottom trench structure, which is connected to the ore extraction access 10.

[0054] The filling structure includes filling borehole 18, filling pipes, and graded filling bodies.

[0055] Specifically, the filling borehole 18 is a downward-sloping hole with a diameter of 180-220mm; the filling borehole 18 corresponding to the goaf of the second-stage pillar is formed by drilling the filling return air channel 12, and the filling borehole 18 corresponding to the goaf of the first-stage stope pillar 6 is formed by drilling the upper segmented rock drilling connecting channel 13; the filling pipeline uses a wear-resistant flexible hose of φ108-133mm, which is laid along the filling borehole 18 into the goaf.

[0056] The specific mining method steps are as follows:

[0057] Step 1: Each mining section is based on a block as the production unit, with the blocks arranged perpendicular to the ore body strike, and the parameters are as described above; all development and preparation works are arranged on the side away from the water-rich rock group to avoid excavating shafts and tunnels in the water-rich layer.

[0058] Step 2: Deep hole grouting is used to plug water in the footwall and reinforce the surrounding rock of the hanging wall of the second-step pillar. The hanging wall grouting uses ultrafine cement-water glass single-liquid grout with a water-cement ratio of 0.8-1.0 and the amount of 45 Baume water glass added is 3-5% of the cement mass. The footwall grouting uses 425 silicate cement-water glass double-liquid grout with a water-cement ratio of 0.8-1.0 and the ratio of water glass to cement is 1:1.

[0059] Step 3: The top 7.0-8.0m of the ore block is mined using the downward approach cemented backfill method. The approach is arranged along the strike of the ore body and mined in two layers, with each layer mined in a three-layer sequence, advancing from the footwall to the hanging wall. After the approach is mined, the bottom is reinforced with steel bars and filled with high-strength tailings cemented backfill. The backfill strength is ≥4.0MPa, serving as the artificial roof for the lower mining. The top layer of the approach roof is supported by a combination of 22mm×L2500mm left-hand threaded anchor bolts, 18.9mm×L6000mm steel strand anchor cables, steel mesh, and shotcrete.

[0060] Step 4: The lower stope is mined sequentially with alternating mining steps, using the downward approach filling method. The approach is perpendicular to the strike of the ore body, and the mining proceeds sequentially from the hanging wall to the footing wall with alternating mining steps. After the approach is mined, reinforcement is laid and backfilled immediately. The backfill strength is ≥3.0MPa. The next layer is mined only after the upper layer is mined. The lowest segment of the ore body is left as the bottom pillar 6 of the first-step stope and will not be mined for the time being.

[0061] Step 5: The pillars are mined sequentially with a three-mining interval. The method of ore extraction followed by backfilling is adopted in the stage of segmented drilling. Ore is extracted through the upward medium-deep holes 23 drilled in the segmented drilling roadway 4, and ore is extracted through the bottom trench and loader. The mining progresses from the footwall to the hanging wall, with the upper segment mining preceding the lower segment.

[0062] Step Six: After the mining is completed, drill the filling borehole 18 diagonally downward from the filling return air channel 12 to the goaf, and lay the filling pipeline for filling; the bottom 10m of the goaf is filled with high strength with a strength ≥3.0MPa, and the middle and upper parts are filled with low strength with a strength ≥1.0MPa to ensure roof connection.

[0063] Step 7: After the second-step pillar filling is completed, the first-step stope pillar 6 is mined using the upward medium-deep hole 23, advancing from the footwall to the hanging wall; after the mining is completed, the filling borehole 18 is drilled from the upper segmented rock-connecting tunnel 13, and the goaf is treated with medium-strength filling with a strength ≥2.0MPa.

[0064] Working principle: This mining structure relies on the intermediate transport roadway 1 and inclined ramp 2, which are located far from the water-rich rock group, to build the basic transport system. The water-blocking grouting hole 20 in the footwall forms a water-blocking curtain to block groundwater in the footwall of the ore body, and the reinforcement grouting hole 21 in the hanging wall forms a reinforcement layer in the surrounding rock of the pillar. The segmented vein roadway 3, segmented drilling roadway 4, layered connecting roadway 7, ore exit connecting roadway 11 and segmented drilling connecting roadway 13 are interconnected to form a mining preparation channel network covering the entire ore block.

[0065] The mining operation uses the layered cutting of the through vein 9 and the layered cutting of the cross roadway 8 as the initial free face. First, the top mining approach 501 is used to mine and fill the artificial roof. Then, the stope is used to mine and fill the stope. A stope pillar 6 is reserved at the bottom of the stope. The pillar is protected by the filling bodies on both sides. The ore is dropped from the medium-deep hole 23 in the segmented drilling roadway 4 and transferred through the ore exit approach 10. The pillar is recovered after the pillar is filled.

[0066] The treatment of the goaf is achieved by drilling filling boreholes 18 at an angle. The filling boreholes 18 for the pillar goaf are drilled from the filling return air channel 12, and the filling boreholes 18 for the bottom pillar goaf are drilled from the segmented rock drilling connecting channel 13. The filling pipeline is laid along the borehole to the goaf to complete the filling and roof connection, and finally a stable support is formed.

[0067] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0068] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A frame-type backfill mining method suitable for underground mineral deposits under extreme geological conditions, characterized in that, Includes the following steps: Step 1: Each mining section is based on a block as the production unit. The blocks are arranged perpendicular to the strike of the ore body. All development and preparation works are arranged on the side away from the water-rich rock group. Step 2: Drill water-blocking grouting holes (20) in the footwall surrounding rock of the ore body to form a water-blocking curtain, and drill upper wall reinforcement grouting holes (21) in the upper wall surrounding rock of the second step pillar mining area for reinforcement; Step 3: The top mining area of ​​the ore block is mined using the downward approach cemented backfilling method. After the top mining approach (501) is completed, high-strength cemented backfilling is carried out to form an artificial roof to protect the lower mining area. Step 4: First, mine the stope in the lower area. The stope is mined using the downward access backfilling method. After the access backfilling is completed, cemented backfilling is carried out immediately. The ore body of the lowest segment of the stope is left as the bottom pillar of the stope for one step and is not mined for the time being. Step 5: After the stope is backfilled, the second-stage pillar is mined. The second-stage pillar is mined by the segmented rock drilling stage followed by backfilling method, and the ore is dropped through the upward medium-deep hole (23). Step 6: After the pillar is mined out, drill a downward-sloping filling borehole (18) to the goaf, lay filling pipes for graded filling and roof connection. After the second step pillar filling is completed, the first step stope pillar (6) is mined by using an upward medium-deep hole (23). After the mining is completed, the filling borehole (18) is drilled to fill the goaf.

2. The frame-type backfilling mining method for underground deposits under extreme geological conditions according to claim 1, characterized in that, In step three, the top mining approach (501) is arranged in two layers along the ore body strike. Each layer adopts a mining sequence of three mining passes per layer, advancing from the footwall to the hanging wall. After the mining of the approach is completed, steel bars are laid at the bottom and high-strength tailings are cemented and backfilled. The strength of the backfill is ≥4.0MPa. After the top mining approach (501) of the uppermost layer is excavated, the roof is supported by 22mm×L2500mm left-hand threaded anchor bolts, 18.9mm×L6000mm steel strand anchor cables, steel mesh and shotcrete.

3. The frame-type backfilling mining method for underground deposits under extreme geological conditions according to claim 1, characterized in that, In step four, the stope adopts a one-alternate-one-mining sequence. The stope mining approach (502) in step one is arranged perpendicular to the strike of the ore body and advances from the hanging wall to the footing wall in an alternating-one-mining sequence. After the approach is mined, steel bars are laid at the bottom and high-strength full tailings cemented backfill is carried out. The strength of the backfill is ≥3.0MPa. After the upper layer is mined, the next layer is mined.

4. The frame-type backfilling mining method for underground deposits under extreme geological conditions according to claim 1, characterized in that, In step five, the second-step pillar adopts a mining sequence of three miners per day, advancing from the lower plate to the upper plate, with the upper section mining preceding the lower section; after the ore falls, it is removed through the bottom trench in conjunction with a loader.

5. The frame-type backfilling mining method for underground deposits under extreme geological conditions according to claim 1, characterized in that, In step one, the length of the ore block along the strike is 50.0-60.0m, the width perpendicular to the strike is equal to the thickness of the ore body, and the height is 50.0-60.0m; the middle section is divided into several segments with a height of 12.0-15.0m, and the height of the first mining area at the top of the ore block is 7.0-8.0m; the width of the stope and pillars are both 12.0-15.0m, and they are all arranged perpendicular to the strike of the ore body.

6. The frame-type backfilling mining method for underground deposits under extreme geological conditions according to claim 1, characterized in that, In step two, the opening diameter of the lower water-blocking grouting hole (20) and the upper reinforcement grouting hole (21) is φ108mm, and the final hole diameter is φ75mm. The hole opening is made of seamless steel pipe with φ89mm, wall thickness of 3mm and length of 5m, and the burial depth is not less than 4.5m. The upper grouting uses ultrafine cement-water glass single liquid grout with a water-cement ratio of 0.8-1.0 and the amount of 45 Baume water glass added is 3-5% of the cement mass. The lower grouting uses 425 silicate cement-water glass double liquid grout with a water-cement ratio of 0.8-1.0 and the ratio of water glass to cement is 1:

1. The thickness of the water-proof curtain layer and the surrounding rock reinforcement layer formed by grouting is not less than 20.0m.

7. The frame-type backfilling mining method for underground deposits under extreme geological conditions according to claim 1, characterized in that, In step six, the diameter of the filling borehole (18) is 180-220mm, and the filling pipe is a wear-resistant hose with a diameter of φ108-133mm; the bottom 10m of the goaf is filled with high strength, with a filling strength ≥3.0MPa, and the middle and upper parts are filled with low strength, with a filling strength ≥1.0MPa.

8. A frame-type backfilling mining method for underground deposits under extreme geological conditions according to claim 1, characterized in that, In step seven, after the first-step stope pillar (6) is mined out, medium-strength backfilling is used, with a backfill strength ≥2.0MPa; underground waste rock can be dumped into the goaf through the segmented rock drilling connecting tunnel (13) for auxiliary backfilling.

9. A frame-type backfilling mining method for underground deposits under extreme geological conditions according to claim 1, characterized in that, In step three, when the top mining approach (501) is being mined, fresh air enters the working face through the layered connecting roadway (7) and the layered cutting cross passage (9), and polluted air returns through the filling return air shaft (16) and the filling return air cross passage (12). When the first-step stope mining approach (502) is being mined, fresh air enters the working face through the layered connecting roadway (7) and the layered cutting cross passage (8), and polluted air returns to the upper and middle sections through the road filling return air shaft (17). When the second-step pillar mining is being mined, fresh air enters the working face through the middle section intake air shaft (14) and the inclined roadway (2), and polluted air returns to the upper and middle sections through the middle section return air shaft (15).

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