A method for continuous grouting and backfilling of waste rock deposits in fractured ore bodies

Abstract

A continuous mining and filling method for waste rock piles in fractured ore bodies, employing a "retreating cutting + waste rock pile grouting" process system, significantly reduces the amount of new mining and cutting work, resulting in a more concentrated and rational roadway layout. This allows for full reuse of existing works, effectively reducing the mining-to-cutting ratio, construction costs, and construction period. Strict control of the single cutting span within the range of 7m to 8m, combined with pre-reserved upper wall support, bolt-and-cable joint support, and precise control of blasting vibration, significantly reduces disturbance to the fractured surrounding rock, improves the stability of key upper layers, and avoids the risks of collapse and delamination. Relying on the high-strength cemented filling body formed by waste rock pile grouting, continuous mining and filling can be achieved in the stope without the need for top pillars or intermediate pillars. For high-grade ore blocks, reinforced concrete false bottoms are used instead of bottom pillars, ensuring stope stability and effectively reducing ore dilution and loss, achieving a dual improvement in resource recovery rate and economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of underground metal mine backfilling mining technology, and in particular relates to a method for continuous grouting and backfilling of waste rock piles suitable for fractured ore bodies. Background Technology

[0002] During the mining of deep, high-stress, and fractured surrounding rock ore bodies, the surrounding rock grade is generally III-IV, which presents problems such as large loosening zone in the stope, thin ore body thickness, weak stability, and easy occurrence of roof collapse and stope instability.

[0003] To maintain stope stability, paste filling is typically used. However, while conventional paste filling provides high strength, it still has the following drawbacks: ① High-concentration slurry has high pipeline resistance and a high risk of pipe blockage; ② High filling cost and difficulty in large-scale fine material preparation; ③ Large pieces of waste rock cannot be utilized in situ.

[0004] In addition, although crushed ore bodies can utilize large amounts of waste rock underground as aggregate and cement the waste rock deposits into a whole through grouting to form a supporting key layer and achieve "mining and filling simultaneously", existing mining methods still have not solved the following technical pain points: ① Insufficient control of the single span in the retreat cutting stope leads to large disturbance in the hanging wall; ② The slurry in the waste rock pile has poor permeability and insufficient fluidity, making it difficult to form a uniform and high-strength cementitious body; ③ It cannot achieve continuous "mining-filling" cycle operation, resulting in low mining efficiency.

[0005] Therefore, there is an urgent need for a new method for continuous mining and filling of waste rock grouting that can operate stably under fractured ore body conditions, support continuous mining, reduce backfilling costs, and has high safety. Summary of the Invention

[0006] To address the problems of existing technologies, this invention provides a continuous mining and filling method for waste rock piles in fractured ore bodies. Employing a "retreating cutting + waste rock pile grouting" process system, it significantly reduces the amount of new mining and cutting work, resulting in a more concentrated and rational roadway layout. This allows for full reuse of existing works, effectively reducing the mining-to-cutting ratio, construction costs, and construction period. Strict control of the single cutting span within the range of 7m to 8m, combined with pre-reserved upper wall support, bolt-and-cable joint support, and precise control of blasting vibration, significantly reduces disturbance to the fractured surrounding rock, improves the stability of key upper layers, and avoids the risks of collapse and delamination. Relying on the high-strength cemented filling body formed by waste rock pile grouting, the stope can achieve simultaneous mining and filling without the need for top pillars or intermediate pillars. For high-grade ore blocks, reinforced concrete false bottoms are used instead of bottom pillars, ensuring stope stability and effectively reducing ore dilution and loss, achieving a dual improvement in resource recovery rate and economic benefits.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a method for continuous grouting and backfilling of waste rock deposits suitable for fractured ore bodies, comprising the following steps: Step 1: Layout of mining and cutting operations and formation of working space; Inside the ore block, through-cutting, drilling, and cutting tunnels are arranged along the strike of the ore body to form an initial free face. Based on the thickness of the ore body and the characteristics of the fractured surrounding rock, a 0.5m thick retaining wall layer is reserved in the hanging wall. Step Two: Blasting and Cutting Operation; The retreating blasting cutting method is used to mine along the ore body, and the single cutting advance length is controlled at 7m to 8m. Step 3: Construction of the waste rock accumulation body; After a single cutting operation is completed, the waste rock from the mine is scattered into the goaf and compacted to form a waste rock accumulation. Step 4: Grouting and filling; Cement grout is injected into the waste rock pile, and the grout is uniformly penetrated to the entire cross-section of the waste rock pile through gravity flow or low-pressure grouting to form a cemented waste rock filling body. Step 5: Continuous mining and charging cycle; After the cemented waste rock backfill reaches its initial strength, the next round of blasting and cutting operations, waste rock accumulation and grouting are carried out. The above steps are repeated until the entire layer is completely mined.

[0008] In step two, a rock drill is used to horizontally arrange blasting holes, and the depth of the blasting holes is the thickness of the ore body minus the thickness of the retaining layer.

[0009] In step two, an electronic detonator micro-delay initiation method is used, and the blasting vibration velocity is controlled within 1.5 cm / s.

[0010] In step two, after a single ore drop, timely ventilation, hazard removal, and preliminary ore extraction are required to provide space for support and backfilling operations. The stability of the hanging wall is ensured by combining intermittent support with short-cut controlled blasting.

[0011] In step three, waste rock is transported to the mining area using a chute or conveyor belt, and then thrown into the cutting space by a rock-throwing machine. The particle size of the waste rock is controlled between 30mm and 300mm.

[0012] In step three, the height of the waste rock pile needs to match the height of the mining area. The waste rock is spread and repeatedly pushed and compacted by a loader and a leveler until the waste rock pile is compacted.

[0013] In step three, the stockpiling ratio of the waste rock pile shall not exceed 70%.

[0014] In step four, the mass concentration of cement slurry is 55% to 57%. Detachable grouting pipes and venting pipes are pre-arranged on the top plate of the mining area. The grouting pipes are provided with cross-shaped outlet holes to allow the cement slurry to seep in multiple directions.

[0015] The grouting pipes are arranged along the direction of the ore body, and the total length of the grouting pipes is consistent with the length of a single cut. The grouting pressure is controlled at 0.2MPa to 0.4MPa, and the average flow velocity of the cement slurry is controlled at 0.06m / s to 0.15m / s.

[0016] In step four, the initial strength formation time of the waste rock cemented backfill shall not be less than 24 hours, and the initial strength of the waste rock cemented backfill shall be controlled between 1.2 MPa and 1.5 MPa.

[0017] The beneficial effects of this invention are: This invention relates to a continuous mining and filling method for waste rock piles in fractured ore bodies. It employs a "retreating cutting + waste rock pile grouting" process system, significantly reducing the amount of new mining and cutting work, resulting in a more concentrated and rational roadway layout. This allows for full reuse of existing works, effectively reducing the mining-to-cutting ratio, construction costs, and construction period. Strict control of the single cutting span within the range of 7m to 8m, combined with pre-reserved upper wall support, bolt-and-cable joint support, and precise control of blasting vibration, significantly reduces disturbance to the fractured surrounding rock, improves the stability of key upper layers, and avoids the risks of collapse and delamination. Relying on the high-strength cemented filling body formed by waste rock pile grouting, continuous mining and filling can be achieved in the stope without the need for top pillars or intermediate pillars. For high-grade ore blocks, reinforced concrete false bottoms are used instead of bottom pillars, ensuring stope stability and effectively reducing ore dilution and loss, achieving a dual improvement in resource recovery rate and economic benefits. Attached Figure Description

[0018] Figure 1 This is a schematic diagram illustrating the operational principle of a continuous grouting and filling method for waste rock piles in fractured ore bodies, according to the present invention. Figure 2 for Figure 1 Sectional view of AA in the middle; Figure 3 for Figure 1 Cross-sectional view of the middle section (BB); In the diagram, 1—intermediate transport roadway, 2—mining area ramp, 3—through vein, 4—ore pass, 5—blasting hole, 6—rock drilling roadway, 7—ventilation shaft, 8—segmented roadway, 9—layered connecting roadway, 10—artificial false bottom, 11—waste rock cemented backfill. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0020] like Figures 1 to 3 As shown, a method for continuous grouting and backfilling of waste rock deposits suitable for fractured ore bodies includes the following steps: Step 1: Layout of mining and cutting operations and formation of working space; Inside the ore block, through-cutting tunnels 3, drilling tunnels 6, and cutting tunnels are arranged along the strike of the ore body to form an initial free face. Based on the thickness of the ore body and the characteristics of the fractured surrounding rock, a 0.5m thick retaining wall layer is reserved in the hanging wall.

[0021] Step Two: Blasting and Cutting Operation; The retreating blasting cutting method is used for mining along the strike of the ore body, with the single cutting advance length controlled at 7m-8m. Specifically, blasting holes 5 are horizontally arranged using a rock drill, with the hole depth of blasting holes 5 being the ore body thickness minus the thickness of the retaining wall layer. Electronic detonators are used for micro-delay initiation, and the blasting vibration velocity is controlled within 1.5cm / s to reduce disturbance to the fractured surrounding rock in the hanging wall. After each ore drop, timely ventilation, hazard removal, and preliminary ore extraction are required to provide space for support and backfilling operations. A combination of intermittent support and short-advance controlled blasting is used to ensure the stability of the hanging wall. It is important to note that ventilation after blasting must be at least 30 minutes, followed by cleaning of the working face and preliminary ore extraction at a 60% extraction rate.

[0022] Step 3: Construction of the waste rock accumulation body; After a single cut is completed, the waste rock from the mine is scattered into the goaf and compacted to form a waste rock pile. Specifically, the waste rock is transported to the stope using a chute or conveyor belt, and then injected into the cutting space by a rock-throwing machine. The particle size of the waste rock is controlled between 30mm and 300mm. The pile height of the waste rock pile needs to match the stope height. The waste rock is spread and repeatedly pushed and compacted by a loader and a leveler until the waste rock pile is compacted, thereby improving the density and permeability of the waste rock pile. The stockpiling rate of the waste rock pile should not exceed 70% to avoid the excessive height of the waste rock pile, which would lead to poor permeability of the cement slurry and affect the strength of the waste rock cemented backfill 11.

[0023] Step 4: Grouting and filling; Cement grout is injected into the waste rock pile, and the grout is uniformly permeated to the entire cross-section of the waste rock pile through gravity flow or low-pressure grouting to form a cemented waste rock backfill 11. Specifically, the mass concentration of the cement grout is 55% to 57%. Removable grouting pipes and venting pipes are pre-installed on the top plate of the mining area. The grouting pipes have cross-shaped outlet holes to allow for multi-directional seepage of the cement grout. It should be noted that the optimal mass concentration of the cement grout is 55%, because when the mass concentration of the cement grout exceeds 57%, the fluidity of the cement grout will decrease. Therefore, using a cement grout with a mass concentration of 55% provides the best penetration effect, allowing the cement grout to flow throughout the entire waste rock pile to form a high-density cemented waste rock backfill 11. The grouting pipes are arranged along the strike of the ore body, with the total length of the grouting pipes consistent with the length of a single cut. The grouting pressure is controlled between 0.2 MPa and 0.4 MPa to avoid grout leakage, erosion of the rockfill, or damage to the surrounding rock due to excessive pressure. The average flow velocity of the cement grout is controlled between 0.06 m / s and 0.15 m / s. Several detachable grouting pipes are assembled in series to form a filling pipe, and an exhaust pipe ensures the smooth discharge of air during grouting and infiltration. The initial strength formation time of the waste rock cemented filling body 11 is not less than 24 hours, and the initial strength of the waste rock cemented filling body 11 is controlled between 1.2 MPa and 1.5 MPa.

[0024] Step 5: Continuous mining and charging cycle; After the cemented waste rock backfill 11 reaches an initial strength of 1.2MPa to 1.5MPa, the next round of blasting and cutting operations, waste rock accumulation, and grouting are carried out. The above steps are repeated until the entire layer is completely mined. The whole process realizes a continuous cycle of "mining a section, backfilling a section, and stabilizing a section". The cemented waste rock backfill 11 always closely follows the advance of the mining area and serves as temporary support for the new round of cutting. For high-grade ore blocks, reinforced concrete artificial false bottom 10 is used to replace the bottom pillar, which not only ensures the stability of the mining area, but also effectively reduces ore dilution and loss, and achieves a double improvement in resource recovery rate and economic benefits.

[0025] The solutions in the embodiments are not intended to limit the scope of protection of the present invention. All equivalent implementations or modifications that do not depart from the present invention are included in the scope of protection of the present invention.

Claims

1. A method for continuous grouting and backfilling of waste rock deposits in fractured ore bodies, characterized in that, Includes the following steps: Step 1: Layout of mining and cutting operations and formation of working space; Inside the ore block, through-cutting, drilling, and cutting tunnels are arranged along the strike of the ore body to form an initial free face. Based on the thickness of the ore body and the characteristics of the fractured surrounding rock, a 0.5m thick retaining wall layer is reserved in the hanging wall. Step Two: Blasting and Cutting Operation; The retreating blasting cutting method is used to mine along the ore body, and the single cutting advance length is controlled at 7m to 8m. Step 3: Construction of the waste rock accumulation body; After a single cutting operation is completed, the waste rock from the mine is scattered into the goaf and compacted to form a waste rock accumulation. Step 4: Grouting and filling; Cement grout is injected into the waste rock pile, and the grout is uniformly penetrated to the entire cross-section of the waste rock pile through gravity flow or low-pressure grouting to form a cemented waste rock filling body. Step 5: Continuous mining and charging cycle; After the cemented waste rock backfill reaches its initial strength, the next round of blasting and cutting operations, waste rock accumulation and grouting are carried out. The above steps are repeated until the entire layer is completely mined.

2. The method for continuous grouting and backfilling of waste rock deposits suitable for fractured ore bodies according to claim 1, characterized in that: In step two, a rock drill is used to horizontally arrange blasting holes, and the depth of the blasting holes is the thickness of the ore body minus the thickness of the retaining layer.

3. The method for continuous grouting and backfilling of waste rock deposits in fractured ore bodies according to claim 1, characterized in that: In step two, an electronic detonator micro-delay initiation method is used, and the blasting vibration velocity is controlled within 1.5 cm / s.

4. A method for continuous grouting and backfilling of waste rock deposits suitable for fractured ore bodies according to claim 1, characterized in that: In step two, after a single ore drop, timely ventilation, hazard removal, and preliminary ore extraction are required to provide space for support and backfilling operations. The stability of the hanging wall is ensured by combining intermittent support with short-cut controlled blasting.

5. A method for continuous grouting and backfilling of waste rock deposits suitable for fractured ore bodies according to claim 1, characterized in that: In step three, waste rock is transported to the mining area using a chute or conveyor belt, and then thrown into the cutting space by a rock-throwing machine. The particle size of the waste rock is controlled between 30mm and 300mm.

6. A method for continuous grouting and backfilling of waste rock deposits suitable for fractured ore bodies according to claim 1, characterized in that: In step three, the height of the waste rock pile needs to match the height of the mining area. The waste rock is spread and repeatedly pushed and compacted by a loader and a leveler until the waste rock pile is compacted.

7. A method for continuous grouting and backfilling of waste rock deposits suitable for fractured ore bodies according to claim 1, characterized in that: In step three, the stockpiling ratio of the waste rock pile shall not exceed 70%.

8. A method for continuous grouting and backfilling of waste rock deposits in fractured ore bodies according to claim 1, characterized in that: In step four, the mass concentration of cement slurry is 55% to 57%. Detachable grouting pipes and venting pipes are pre-arranged on the top plate of the mining area. The grouting pipes are provided with cross-shaped outlet holes to allow the cement slurry to seep in multiple directions.

9. A method for continuous grouting and backfilling of waste rock deposits in fractured ore bodies according to claim 8, characterized in that: The grouting pipes are arranged along the direction of the ore body, and the total length of the grouting pipes is consistent with the length of a single cut. The grouting pressure is controlled at 0.2MPa to 0.4MPa, and the average flow velocity of the cement slurry is controlled at 0.06m / s to 0.15m / s.

10. A method for continuous grouting and backfilling of waste rock deposits in fractured ore bodies according to claim 1, characterized in that: In step four, the initial strength formation time of the waste rock cemented backfill shall not be less than 24 hours, and the initial strength of the waste rock cemented backfill shall be controlled between 1.2 MPa and 1.5 MPa.

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