Deep hole static fracturing and blasting combined mining dilution control method

Abstract

The method of deep hole static fracturing combined with blasting for recovery and dilution control is as follows: the surrounding fracturing holes are arranged in the edge area of the two-step stope adjacent to the one-step filling body, the blasting deep holes are concentratedly arranged in the core area of the ore body in the middle of the stope, the blasting deep holes and the auxiliary blasting holes are arranged in parallel, the auxiliary vibration hole blasting auxiliary hole is arranged in the middle, the joint operation ore falling process strictly follows the order of “first static fracturing and then sublevel blasting”, the precise partition of blasting load and fracturing weakening is realized, the direct damage of blasting vibration to the filling body is maximally isolated, and there are six process steps and conditions, which can solve the technical problems of high ore dilution rate caused by the mixing of filling body and ore pile due to insufficient filling body strength or complex construction in the recovery process of existing two-step stope, and can also consider safety, process simplification and dilution control.

Description

Technical Field

[0001] This invention relates to the field of underground mining technology for metal mines, specifically to a method for controlling dilution during deep-hole static fracturing and blasting combined mining. Background Technology

[0002] The open-stope backfilling method is an important technical means in mining. It has significant advantages in improving the recovery rate of ore resources and effectively maintaining ground pressure. The open-stope backfilling method with vertical ore body layout usually adopts the "two-step mining" mode: that is, the mining and tailings backfilling of the first-step stope are completed first, and then the backfill body is used as the support of the surrounding rock on both sides in the second-step stope for subsequent operations. However, the existing technology has the following key defects: First, the strength of the filling body is insufficient: Compared with the original rock, the mechanical strength of the filling body is low, and it is easy to be damaged under the vibration of deep hole blasting, which leads to the collapse of the filling body on both sides of the two-step mining area. A large amount of filling body is mixed into the ore pile, which significantly increases the ore dilution rate and affects the resource utilization efficiency and mine economic benefits; Second, the existing strengthening or improvement technology has the following limitations: (1) Suspended reinforced filling body technology, such as CN108547660 B "Suspended reinforced filling body goaf filling method", this technology attempts to improve the stability of the goaf filling body by erecting a suspension fixed beam and flexible net through traction rope, but its construction requires the pre-arrangement of traction rope and fixed beam. When the mining area is long or high, the flexible net roll is large in volume and heavy in weight, which leads to the complexity of the construction process and a significant increase in difficulty; In addition, some people have noticed that the flexible net is prone to sticking to the wall during the descent process, and the actual support effect is difficult to guarantee; (2) Filling material technology containing straw fiber, such as CN 107500686 B "A filling material containing rice straw fiber and its application in filling mining" This technology improves the compressive and fracture resistance of the filling body after solidification by incorporating rice straw fiber. However, the addition of rice straw fiber reduces the fluidity of the slurry and is prone to blockage during underground filling pipeline transportation, which limits the feasibility and efficiency of its industrial application.

[0003] In summary, current technologies for enhancing the stability and construction feasibility of backfill bodies during two-step mining operations generally suffer from drawbacks such as complex construction procedures and unstable results. They are insufficient to effectively address the ore dilution problem caused by backfill body damage. The industry urgently needs an innovative solution that balances structural stability and ease of construction to overcome these technical bottlenecks.

[0004] Therefore, it is of great significance to develop a method for controlling dilution in deep-hole static fracturing and blasting combined with open-hole filling in the mining area. Summary of the Invention

[0005] The objective of this invention is to overcome the shortcomings of the prior art and provide a method for controlling ore dilution in deep-hole static fracturing and blasting combined mining. This method can solve the technical problem of high ore dilution rate caused by the mixing of backfill material into the ore pile due to insufficient strength of the backfill material or complex construction in the existing two-step mining process. It can also take into account safety, process simplification and dilution control.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] The combined deep-hole static fracturing and blasting mining dilution control method involves arranging peripheral fracturing holes in the edge area of ​​the second-stage stope adjacent to the first-stage backfill, while blasting deep holes are concentrated in the core area of ​​the ore body in the middle of the stope. The blasting deep holes and auxiliary blasting holes are arranged in parallel, with auxiliary vibration holes and blasting auxiliary holes centrally located. The combined operation strictly follows the sequence of "static fracturing first, then staged blasting" to achieve precise zoning of blasting load and fracturing weakening, maximizing the isolation of direct damage to the backfill from blasting vibration. The specific process steps and conditions are as follows:

[0008] S1. Stope mining and backfilling: After the ore mining of the first-stage stope is completed, stope backfilling operations are carried out in the goaf to construct a cemented backfill body with preliminary support capacity, which serves as a stable surrounding rock support structure on the left and right sides of the second-stage stope, providing safe operating conditions for the subsequent second-stage mining.

[0009] S2. Construction of the ore extraction system in the lower part of the stope: Construct ore extraction channels and ore extraction routes in the lower part of the two-step stope, lay out medium-deep holes inside the ore extraction channels, and form ore extraction trenches by blasting through medium-deep holes to build a dedicated channel for subsequent ore dropping and transportation, ensuring smooth ore extraction.

[0010] S3. Construction of the upper drilling system in the mining area: Drilling roadways and drilling chambers are constructed at the corresponding positions in the upper part of the two-step mining area. In combination with the occurrence characteristics of the ore body at the end or middle, cutting shafts are constructed and cutting slots are formed. The cutting slots are used as the core structure for controlling the ore falling range and the blasting free face.

[0011] S4. Precise layout of deep holes in different zones in the stope: Deep fracturing holes are specially arranged in the drilling chamber and the area around the stope adjacent to the filling bodies on both sides; blasting deep holes are arranged in the core area of ​​the ore body in the middle of the stope away from the filling bodies; blasting auxiliary holes are arranged at the preset intervals outside the fracturing holes around the perimeter, so as to realize the functional zoning and process coordination of fracturing, blasting and auxiliary vibration holes, and the hole diameters of the three types of holes are consistent.

[0012] S5. Combined Static Fracturing and Blasting Operation for Ore Drop: Strictly follow the procedure of first performing hydraulic static fracturing and then performing segmented blasting. First, perform segmented hydraulic static fracturing on the deep fracturing holes near the cutting groove. Through hydraulic pre-fracturing, directional micro-cracks are formed inside the surrounding ore and rock, achieving pre-weakening of the ore and rock. Throughout the process, only slight disturbances are generated to the surrounding filling body, without damaging the integrity of the filling body. Subsequently, the explosives are loaded in the blasting auxiliary holes and blasting deep holes, and segmented blasting is carried out to drop the ore. The vibration of the blasting auxiliary holes drives the pre-weakened ore and rock to collapse smoothly, avoiding the blasting shock wave from directly impacting the filling body on both sides, thus reducing the risk of the filling body collapsing and mixing into the ore from the source.

[0013] S6. Cyclic mining and final backfilling: The deep holes in the stope are divided into several mining units. The above-mentioned joint operation ore extraction process is repeated group by group to complete all ore mining operations in the two-step stope. After mining is completed, the goaf of the two-step stope is backfilled as a whole to form a stable overall stope structure and ensure stope safety.

[0014] Compared with the prior art, the innovative points and advantages or effects of this invention are as follows:

[0015] (1) Improved structural stability: Hydraulic static fracturing only applies micro-disturbance to the backfill around the stope, avoiding the destruction of the backfill caused by direct blasting, thereby significantly enhancing the overall structural stability of the stope;

[0016] (2) Simplified construction process: By dividing the area into holes and arranging them in a combined manner, the pre-installation process of complex support structures (such as flexible nets and reinforced beams) is eliminated, which reduces the difficulty and cost of construction.

[0017] (3) Effective control of dilution rate: Deep hole blasting is concentrated on the ore and rock in the middle area of ​​the stope, and the auxiliary holes drive the ore and rock in the fracturing area to fall into the ore. The arrangement of fracturing holes around the perimeter reduces the amount of filling material mixed into the ore pile, directly solving the problem of ore dilution caused by the destruction of filling material.

[0018] (4) Applicability and efficiency are both taken into account: This method is applicable to ore bodies with different occurrence characteristics (such as end or middle cutting grooves), and by combining static fracturing and blasting, it takes into account both ore extraction efficiency and safety.

[0019] In summary, this invention, through process optimization and mechanics-based design, provides a safe, reliable, easy-to-operate, and highly effective dilution control technical approach for two-stage mining in deep mines. It fills the gap in existing technologies for controlling mining stability and dilution under complex conditions and has broad engineering application prospects. The deep-hole static fracturing and blasting combined mining dilution control method of this invention, through zoned borehole layout and fracturing followed by weak vibration blasting, significantly reduces blasting damage and collapse mixing into the backfill bodies on both sides of the two-stage mining area. This achieves: a 3-8 percentage point reduction in ore dilution rate in the two-stage mining area; a 3-10% increase in ore grade; and a significant improvement in the integrity and construction stability of the backfill body. The dilution control effect is reliable, quantifiable, and easy to promote. Attached Figure Description

[0020] Figure 1 This is a front view of a stope subsequently filled in, based on a deep-hole static fracturing and blasting combined mining dilution control method proposed in this invention.

[0021] Figure 2 for Figure 1 The following is a side view of the open area subsequently filled in mining area II-II.

[0022] Figure 3 for Figure 1 The diagram shows a top view of the subsequent filling of the open area.

[0023] Figure 4 This is a schematic diagram of a deep-hole static fracturing and blasting combined mining dilution control method proposed in this invention for subsequent backfilling of the stope.

[0024] The symbols in the attached diagram represent:

[0025] 1. Drilling through veins 2. Ore-exporting through veins 3. Cemented backfill 4. Pillars 5. Stopes 6. Drilling chambers 7. Drilling chamber connecting passages 8. Return airway 9. Ore-exporting access road 10. Transport along the vein 11. Peripheral fracturing holes 12. Blasting auxiliary holes 13. Deep blasting holes

[0026] The present invention will now be described in further detail with reference to the accompanying drawings. Detailed Implementation

[0027] like Figures 1-4As shown, the combined deep-hole static fracturing and blasting mining dilution control method involves arranging peripheral fracturing holes 11 in the edge area of ​​the two-step stope adjacent to the filling body of the first step, and blasting deep holes 13 concentrated in the core area of ​​the ore body in the middle of the stope. The blasting deep holes 13 and blasting auxiliary holes 12 are arranged in parallel, and the auxiliary vibration holes and blasting auxiliary holes 12 are arranged in the center. The combined operation strictly follows the sequence of "static fracturing first, then segmented blasting" to achieve precise zoning of blasting load and fracturing weakening, and to maximize the isolation of direct damage to the filling body from blasting vibration. The specific process steps and conditions are as follows:

[0028] S1. Stope mining and backfilling: After the ore mining of the first-stage stope is completed, stope backfilling operations are carried out in the goaf to construct a cemented backfill body with preliminary support capacity, which serves as a stable surrounding rock support structure on the left and right sides of the second-stage stope, providing safe operating conditions for the subsequent second-stage mining.

[0029] S2. Construction of the ore extraction system in the lower part of the stope: Construct ore extraction channel 2 and ore extraction access road 9 in the lower part of the two-step stope. Set up medium-deep holes inside ore extraction channel 2, and form ore extraction trench through blasting of medium-deep holes to build a dedicated channel for subsequent ore dropping and transportation, so as to ensure smooth ore extraction.

[0030] S3. Construction of the upper drilling system in the mining area: Drilling roadways and drilling chambers 6 are constructed at the corresponding positions in the upper part of the two-step mining area. In combination with the occurrence characteristics of the ore body at the end or middle, cutting shafts are constructed and cutting grooves are formed. The cutting grooves are used as the core structure for controlling the ore falling range and the blasting free face.

[0031] S4. Precise layout of deep holes in different zones of the stope: Deep fracturing holes are specially arranged in the area of ​​the rock drilling chamber 6 and the area of ​​the stope adjacent to the filling bodies on both sides; blasting deep holes 13 are arranged in the core area of ​​the ore body in the middle of the stope away from the filling bodies; blasting auxiliary holes 12 are arranged at a preset interval outside the fracturing holes 11 around the perimeter, so as to realize the functional zoning and process coordination of the three types of blast holes: fracturing, blasting and auxiliary vibration, and the diameter of the three types of blast holes is consistent.

[0032] S5. Combined Static Fracturing and Blasting Operation for Ore Drop: Strictly follow the procedure of first performing hydraulic static fracturing and then performing segmented blasting. First, perform segmented hydraulic static fracturing on the deep fracturing hole near the cutting groove. Through hydraulic pre-fracturing, directional micro-cracks are formed inside the surrounding ore rock, achieving pre-weakening of the ore rock. Throughout the process, only slight disturbances are generated to the surrounding filling body without damaging the integrity of the filling body. Subsequently, the explosives are loaded in the blasting auxiliary hole 12 and the blasting deep hole 13, and segmented blasting is carried out to drop the ore rock. With the help of the vibration of the blasting auxiliary hole 12, the pre-weakened ore rock is driven to collapse smoothly, avoiding the blasting shock wave from directly impacting the filling body on both sides, thus reducing the collapse of the filling body and the mixing of ore from the source.

[0033] S6. Cyclic mining and final backfilling: The deep holes in the stope are divided into several mining units. The above-mentioned joint operation ore extraction process is repeated group by group to complete all ore mining operations in the two-step stope. After mining is completed, the goaf of the two-step stope is backfilled as a whole to form a stable overall stope structure and ensure stope safety.

[0034] The method of the present invention can be further described as follows:

[0035] The fracturing holes 11 in step S1 are only arranged in the edge area of ​​the second-step stope adjacent to the filling body of the first step. The blasting deep holes 13 are concentrated in the core area of ​​the ore body in the middle of the stope. The blasting deep holes 13 and blasting auxiliary holes 12 are arranged in parallel along the length of the stope.

[0036] In step S1, the blasting auxiliary hole 12 is arranged outside the peripheral fracturing hole 11 to achieve precise isolation of the blasting load and minimize the direct damage of blasting vibration to the filling body.

[0037] The combined operation of step S5 strictly follows the sequence of "static fracturing first, followed by segmented blasting". The hydraulic static fracturing process is free of strong vibration and shock waves, and only completes the pre-fracture and weakening of the ore and rock without damaging the integrity of the filling body.

[0038] The subsequent blasting in step S5 is only aimed at the central ore and rock. The blasting auxiliary hole 12 only plays an auxiliary role in causing the pre-fractured ore and rock to collapse, which greatly reduces the probability of the filling body collapsing and mixing into the ore pile, and directly controls the ore dilution rate.

[0039] Step S5 does not require the pre-installation of external reinforced support structures such as suspension fixed beams and flexible nets, nor does it require the addition of modified materials such as straw fiber to the filling slurry. The entire process is carried out through the zoned layout of blast holes and the fracturing-blasting synergistic process, which can achieve dilution control, simplify downhole construction procedures, avoid technical defects such as filling pipe blockage and flexible net wall failure, and ensure the stability of construction efficiency and dilution control effect.

[0040] Example 1

[0041] In a large copper ore body mine, the ore body has a middle section height of 50m. The mine employs a large-diameter deep-hole backfilling method. The stope is arranged vertically to the ore body, with a length or thickness of 50m and a width of 15m. The stope mining is divided into two steps: After the first step of stope mining is completed, tailings are used to cement and backfill the stope, forming a preliminary support structure. The second step of mining involves: constructing a bottom cutting groove and blast holes at the bottom of the second-step stope, including drilling through the vein 1 and the ore access road 9. A 2m × 2m cutting shaft, 12-15m high, is set at the center of the bottom of the stope. Through the cutting shaft, slotting blasting is carried out along the length of the stope to form the bottom cutting groove. Subsequently, upward fan-shaped blast holes with a height of 12-15m are arranged in the rock drilling vein, with the inclination angle of the side holes not less than 50°; V-shaped grooves are formed and ore extraction channels are constructed. Two to three rows of blasting operations are carried out sequentially from the bottom cutting groove to both sides of the stope. After the ore is shoveled out through the ore extraction access road 9, a V-shaped groove is gradually formed at the bottom of the stope. This V-shaped groove serves as the space for subsequent deep-hole blasting and ore extraction and a centralized ore receiving channel, ensuring the orderly collapse of ore and reducing disturbance to the filling body; point pillars and cutting grooves are set at the top of the stope. The rock drilling vein connecting road 7 and the rock drilling vein are arranged at the top of the stope, and point pillars are reserved on both sides every 4-5m along the rock drilling chamber 6. The point pillars are 2.0m wide and 4-5m wide, and are used to support the structural stability of the rock drilling chamber. Based on the ore body's occurrence characteristics, a 2m×2m cutting shaft is installed at the top end or center of the stope, with its depth corresponding to the uncut ore height. Through the cutting shaft, slotting blasting is performed along the length of the stope to form a cutting groove at the top of the stope. Deep holes are arranged in zones within the stope's drilling chambers, with a diameter of 126mm and a spacing of 3.0~3.5m×3.0~3.5m. The holes around the stope are designed as peripheral fracturing holes (11) for static fracturing. The deep holes in the central area serve as deep-hole blasting holes (13) for subsequent efficient ore extraction. To ensure smooth ore and rock collapse in the peripheral fracturing hole area, an auxiliary blasting hole (12) with the same diameter as the deep holes is additionally arranged 1.5m outside the peripheral holes. For joint operations and safety control, to ensure the safety of the mining process, the deep holes are divided into groups of 2~3 rows. In each operation, hydraulic fracturing is first performed on the perimeter fracturing holes 11. The fracturing holes are divided into three sections, each maintained at high pressure using a sealer. The fracturing pressure is controlled at 15-20 MPa, and the fracturing duration for each section is 30 minutes. After the perimeter holes are pre-fracturing, the charging and blasting operations are simultaneously carried out on the auxiliary blasting holes 12 and the deep-hole blasting holes 13 within the group. After each blasting operation is completed, the ore is extracted using the shovel loading system at the bottom of the stope. Subsequent groups operate in this cyclical manner until all mining operations in the two-step stope are completed.

[0042] After adopting a combined deep-hole static fracturing and blasting mining method, the dilution rate in the two-step stope was reduced from 25% to 14%, and the copper grade of the ore from the stope increased from 1.9% to 2.1%. This embodiment effectively solves the problem of dilution caused by insufficient backfill strength or complex construction in existing technologies by using zoned hole layout (peripheral holes are hydraulic fracturing holes, and central holes are blasting holes), combining the micro-disturbance characteristics of static fracturing with the high efficiency of deep-hole blasting, thus providing reliable technical support for safe and efficient mine production.

[0043] Example 2

[0044] Taking a large, thick gold ore body as an example, the ore body has a middle section height of 50m. The large-diameter deep-hole backfilling method is used, with the stope arranged vertically to the ore body. The stope length is 45m (or the ore body thickness), and the width is 12m. Stope mining is divided into two steps: After the first step of stope mining is completed, tailings are used to cement and backfill the stope, forming a preliminary support structure. The second step of mining involves: the arrangement of cutting grooves and blast holes at the bottom of the stope; the construction of rock drilling vein 1 and ore access road 9 at the bottom of the second-step stope; and the setting of a 1.8m × 1.8m cutting shaft with a height of 15m at the center of the bottom of the stope. Through the cutting shaft, slotting blasting is carried out along the length of the stope to form the bottom cutting groove. Subsequently, upward-facing fan-shaped blast holes with a height of 15m are arranged within the drilling vein, with the side hole inclination angle not less than 45°. V-shaped groove formation and ore extraction channel construction: 2-3 rows of blasting operations are carried out sequentially from the bottom cutting groove towards both sides of the stope. After the ore is shoveled out through the ore extraction access road 9, a V-shaped groove gradually forms at the bottom of the stope. This V-shaped groove serves as the space for subsequent deep-hole blasting and a centralized ore receiving channel, ensuring orderly ore caving and reducing disturbance to the backfill. Point pillars and cutting grooves are set at the top of the stope. A drilling vein connecting road 7 and drilling veins are arranged at the top of the stope, and point pillars are reserved on both sides every 5m along the drilling chamber 6. The point pillars are 2.0m wide × 5m in size and are used to support the structural stability of the drilling chambers. Based on the ore body occurrence characteristics, cutting shafts with a specification of 1.8m × 1.8m are set at the top end or center of the stope, with their depth corresponding to the un-mined height of the stope. Cutting trenches are created at the top of the stope by blasting along the length of the cutting shaft. Deep holes are arranged in sections within the drilling chambers along the length of the stope, with a diameter of 126mm and a spacing of 3.0m x 3.0m. The perimeter holes (designed as peripheral fracturing holes 11) are used for static fracturing; the deep holes in the central area serve as deep-hole blasting holes 13 for subsequent efficient ore extraction. To ensure smooth ore and rock caving in the perimeter fracturing hole area, auxiliary blasting holes (12) with the same diameter as the deep holes are arranged 1.5m outside the peripheral holes. For combined operation and safety control, to ensure safety during the mining process, the deep holes are grouped into sets of 2-3 rows. In each operation, hydraulic fracturing is first performed on the perimeter fracturing holes 11. These holes are divided into three sections, each maintained under high pressure using a sealer. The fracturing pressure is controlled between 18 and 25 MPa, and each section lasts for 30 minutes. After the perimeter holes are pre-fracturing, the auxiliary blasting holes 12 and deep-hole blasting holes 13 within the group are simultaneously loaded and blasted. After each blasting operation, ore is extracted using the shovel loading system at the bottom of the stope. Subsequent groups follow this cyclical operation until all mining operations in the two-step stope are completed. After adopting the combined deep-hole static fracturing and blasting mining method, the dilution rate of the two-step stope decreased from 22% to 13%, and the gold grade of the extracted ore increased from 3.1 g / t to 3.5 g / t.

[0045] As described above, the present invention can be well implemented. The above embodiments are only the best implementations of the present invention, but the implementation of the present invention is not limited to the above embodiments. Other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention should be considered equivalent substitutions and are all included within the protection scope of the present invention.

Claims

1. A method for controlling dilution during deep-hole static fracturing and blasting combined mining, characterized in that... Peripheral fracturing holes (11) are arranged in the edge area of ​​the second-stage stope adjacent to the first-stage filling body. Blasting deep holes (13) are concentrated in the core area of ​​the ore body in the middle of the stope. Blasting deep holes (13) and blasting auxiliary holes (12) are arranged in parallel. Auxiliary vibration holes and blasting auxiliary holes (12) are arranged in the center. The joint operation ore cutting process strictly follows the order of "static fracturing first, then segmented blasting" to achieve precise zoning of blasting load and fracturing weakening, and to maximize the isolation of blasting vibration from direct damage to the filling body. The specific process steps and conditions are as follows: S1. Stope mining and backfilling: After the ore mining of the first-stage stope is completed, stope backfilling operations are carried out in the goaf to construct a cemented backfill body with preliminary support capacity, which serves as a stable surrounding rock support structure on the left and right sides of the second-stage stope, providing safe operating conditions for the subsequent second-stage mining. S2. Construction of the mining system in the lower part of the mining area: Construction of the mining channel (2) and mining access road (9) in the lower part of the two-step mining area, laying out medium-deep holes in the mining channel (2), forming mining trenches by blasting through medium-deep holes, building a dedicated channel for subsequent ore dropping and transportation, and ensuring smooth mining. S3. Construction of the upper rock drilling system in the mining area: Construct rock drilling roadways and rock drilling chambers (6) at the corresponding positions in the upper part of the two-step mining area. Combined with the occurrence characteristics of the end or middle part of the ore body, construct cutting shafts and form cutting grooves. Use the cutting grooves as the core structure for controlling the ore falling range and the blasting free face. S4. Precise layout of deep holes in different zones of the mining area: Deep fracturing holes are specially arranged in the area of ​​the rock drilling chamber (6) and the area of ​​the mining area adjacent to the filling bodies on both sides; blasting deep holes (13) are arranged in the core area of ​​the ore body in the middle of the mining area away from the filling bodies; blasting auxiliary holes (12) are arranged at the preset spacing outside the fracturing holes (11) to realize the functional zoning and process coordination of fracturing, blasting and auxiliary vibration holes, and the hole diameters of the three types of holes are kept consistent. S5. Combined static fracturing and blasting operation for ore extraction: Strictly follow the procedure of first hydraulic static fracturing and then segmented blasting. First, segmented hydraulic static fracturing operation is carried out on the deep hole fracturing hole near the cutting groove. Through hydraulic pre-fracturing, directional expansion microcracks are formed in the surrounding ore rock to achieve pre-weakening of the ore rock. The entire process only causes slight disturbance to the surrounding filling body and does not damage the integrity of the filling body. Then, the explosive is loaded in the blasting auxiliary hole (12) and the blasting deep hole (13) and segmented blasting is carried out for ore extraction. With the help of the vibration of the blasting auxiliary hole (12), the pre-weakened ore rock is driven to collapse smoothly, avoiding the blasting shock wave from directly impacting the filling body on both sides, and reducing the collapse of the filling body and mixing with the ore from the source. S6. Cyclic mining and final backfilling: The deep holes in the stope are divided into several mining units. The above-mentioned joint operation ore extraction process is repeated group by group to complete all ore mining operations in the two-step stope. After mining is completed, the goaf of the two-step stope is backfilled as a whole to form a stable overall stope structure and ensure stope safety.

2. The method according to claim 1, characterized in that: The fracturing holes (11) in step S1 are only arranged in the edge area of ​​the second-step stope adjacent to the filling body of the first step. The blasting deep holes (13) are concentrated in the core area of ​​the ore body in the middle of the stope. The blasting deep holes (13) and blasting auxiliary holes (12) are arranged in parallel along the length of the stope.

3. The method according to claim 1 or 2, characterized in that: The step S1 blasting auxiliary hole (12) is arranged outside the peripheral fracturing hole (11) to achieve precise isolation of blasting load and minimize the direct damage of blasting vibration to the filling body.

4. The method according to claim 2, characterized in that: The combined operation of step S5 strictly follows the sequence of "static fracturing first, followed by segmented blasting". The hydraulic static fracturing process is free of strong vibration and shock waves, and only completes the pre-fracture and weakening of the ore and rock without damaging the integrity of the filling body.

5. The method according to claim 2, characterized in that: The subsequent blasting in step S5 is only for the central ore and rock. The blasting auxiliary hole (12) only plays an auxiliary role in causing the pre-fractured ore and rock to collapse, which greatly reduces the probability of the filling body collapsing and mixing into the ore pile, and directly controls the ore dilution rate.

6. The method according to claim 2, 4, or 5, characterized in that: Step S5 does not require the pre-installation of external reinforced support structures such as suspension fixed beams and flexible nets, nor does it require the addition of modified materials such as straw fiber to the filling slurry. The entire process is carried out through the zoned layout of blast holes and the fracturing-blasting synergistic process, which can achieve dilution control, simplify downhole construction procedures, avoid technical defects such as filling pipe blockage and flexible net wall failure, and ensure the stability of construction efficiency and dilution control effect.

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