A two-step stope pre-reinforcement wall large diameter deep hole stage emptying and subsequent filling mining method

Abstract

The present invention discloses a two-step stope pre-reinforced protective wall large-diameter deep hole stage empty site subsequent filling mining method, which is suitable for the recovery of the two-step stope when the filling quality is poor after the recovery and filling of the thick and large ore body in the first-step stope. When recovering the two-step stope, reserved protective walls are designed on both sides of the stope to isolate the one-step stope filling bodies on both sides, and a "∩"-shaped steel strand mesh support is formed by downward long anchor cables and transverse tensioning bars to support and reinforce the reserved protective walls, and then a large-diameter deep hole stage empty site subsequent filling method is used to recover the two-step stope. The present invention can not only effectively reduce the thickness of the reserved protective wall during the recovery of the two-step stope and improve the ore recovery rate, but also significantly improve the strength and stability of the reserved protective wall, ensuring the safety and efficiency of the two-step stope recovery.

Description

Technical Field

[0001] The present invention belongs to the field of underground mining, and particularly relates to a two-step stope pre-reinforced wall protection large-diameter deep hole stage empty stope subsequent filling mining method, which is particularly suitable for the recovery of a thick and large ore body in a two-step stope when the filling quality is poor after the recovery and filling of a first-step stope is completed. Background Art

[0002] In recent years, with the advancement of green mine construction, backfill mining has been widely used in major mines for reasons such as safe operation and delayed surface subsidence. Large-diameter deep hole stage empty field and subsequent backfill mining is widely used in major mines because of its safe mining operation, small amount of mining and cutting engineering, and large production capacity, and has achieved considerable economic benefits. When a thick and large ore body is mined by large-diameter deep hole stage empty field and subsequent backfill mining, the ore body is divided into two steps of mining: the mine room and the pillar. The first step is to mine the mine room. After the mining of the mine room is completed, a higher strength cementing filling body is used to fill the mine room. After the filling and maintenance is completed, the second step is to mine the pillar. After the mining of the pillar is completed, a non-cementing backfilling mining field is used to prevent environmental pollution caused by surface subsidence and reduce the filling cost at the same time.

[0003] The large-diameter deep-hole stage empty-site and subsequent backfill mining method is suitable for ore bodies with medium or higher stability. The basic condition for its use is that the stability of the ore body is medium or higher, and a large open-site exposure area and a long exposure time can be allowed. For mines that choose to adopt this method, when the first-step mine room is mined, the upper and lower plates and the walls on both sides of the mining area are all native rock bodies with medium or higher stability, so the mining difficulty is relatively small, and generally safe and efficient mining can be achieved. When mining in the second step, the walls on both sides of the mining area are the filling bodies formed after the first-step mining. At this time, the filling body is equivalent to an artificial pillar. The strength requirement is not only to be self-supporting, but also to be able to bear a certain load. Therefore, when filling the mine room in the first step, a higher-strength cemented filling body is required, and the filling quality must be guaranteed. In production practice, some mines have problems with the filling quality of the first-step stope due to reasons such as too fine tailings particles, problems with the ratio of cementitious materials, or inadequate filling quality control, resulting in substandard filling quality in the first-step stope, insufficient or even no filling strength, which has brought huge problems to the mining of the second-step pillars. The filling strength of the first-step stope is substandard or no, and the mining of the second-step pillars is risky and difficult. If mining is carried out in the conventional way, the filling in the first-step stope will collapse over a large area, threatening the safety of the operating personnel and equipment, causing a large amount of loss and depletion, and may also cause the risk of surface subsidence and collapse.

[0004] Patent No. CN106121643A discloses a two-step nested combined filling mining method with reserved ore wall. The purpose is to prevent the loss and dilution of ore due to the relatively broken ore rock. The reserved ore wall is used to further prevent the broken surrounding rock from mixing into the stope due to the influence of blasting vibration and causing dilution. Patent No. CN115182728A discloses a downward segmented empty field and subsequent filling mining method, which also divides the ore block into a mine room and a pillar, and adopts medium-deep hole or deep hole rock drilling and blasting from top to bottom for mining. At the same time, the stope is mined in the form of staggered arrangement of the upper and lower middle sections corresponding to the stope to avoid the impact of blasting vibration on the filling body. When the strength of the filling body in the first-step mining area does not meet the standard or has no strength, a certain amount of retaining wall can be considered for the second-step mining. However, in production practice, the thickness of the retaining wall cannot be too thick due to factors such as ore recovery rate. In addition, due to factors such as blasting vibration and long mining cycle during mining, the retaining wall often collapses during mining. Not only does it fail to isolate the low-quality filling body in the first step and prevent it from collapsing, but the original rock blocks caused by the collapse of the retaining wall increase the safety hazard and the large block rate in the mining area.

[0005] In view of the two-step stope recovery under the above conditions and the shortcomings of the existing technology, there is an urgent need for a two-step stope pre-reinforced wall protection large-diameter deep hole stage empty site subsequent filling mining method to solve the problem of safe and efficient recovery of the two-step stope when the filling quality of the first-step stope of thick and large ore bodies is poor, so as to achieve its smooth recovery. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a two-step stope pre-reinforcement wall protection large diameter deep hole stage empty field subsequent filling mining method, which comprises the following steps:

[0007] Step a, delineate the mining range of the second-step stope, reserve retaining walls on both sides of the second-step stope to isolate the filling bodies of the first-step stope on both sides, arrange anchor cable construction tunnels at the boundaries of both sides of the top pillars of the second-step stope, construct a row of downward anchor cable holes along the strike in the anchor cable construction tunnel, and the downward anchor cable holes are located at the midline position of the reserved retaining walls; construct horizontal holes on the side walls of the anchor cable construction tunnel to penetrate the anchor cable construction tunnels of the adjacent second-step stopes, and the horizontal holes are 1.5 to 2 meters away from the bottom plate of the anchor cable construction tunnel and correspond to the positions of the downward anchor cable holes one by one;

[0008] Step b, after the construction of the downward anchor hole is completed, a vertical steel strand and a grouting pipe are installed in the hole, the vertical steel strand is exposed 1.5 to 2m from the hole mouth, and a transverse steel strand is inserted into the transverse borehole as a transverse reinforcement, and the transverse steel strand is exposed 2 to 3m at both ends of the borehole; then the downward anchor hole is grouted twice in the form of hole bottom return, the first grouting pressure is ≥0.5 to 1.0 MPa, and the first grouting is stopped when thick cement slurry flows out of the hole mouth. The second grouting is high-pressure splitting grouting, and the second grouting is carried out 3 to 5 hours after the first grouting, and the second grouting pressure is ≥1.5 to 2.0 MPa. After the second grouting is completed, it is cured for 25 to 30 days;

[0009] Step c, after the maintenance is completed, the vertical steel strands in the downward anchor cable holes are tensioned, and a secondary multi-stage tensioning process is adopted. The first tensioning straightens the steel strands and stabilizes them for 20 to 30 minutes to facilitate the transmission and adjustment of the prestress in the anchor cable. The second tensioning is carried out after the prestress of the first tensioning is stabilized to compensate for the prestress loss. The total tensioning tonnage is not less than the designed tonnage. After the vertical steel strands are tensioned, the vertical steel strands are tensioned and connected with the corresponding transverse steel strands, so that the anchor cables on the adjacent side of the adjacent two-step mining site are supported by the transverse steel strands in a "∩" shape, and the reinforced support of the reserved retaining walls on both sides of the two-step mining site is completed.

[0010] Step d, construct the mining and cutting project, construct a bottom rock drilling tunnel at the bottom of the stope in step 2, which also serves as a receiving tunnel, and forms a bottom mine access; construct a rock drilling chamber at the top of the stope, leave columns in the rock drilling chamber, and then construct a large-diameter deep hole downward in the rock drilling chamber according to the designed hole network parameters;

[0011] Step e, mining in the mine, first use the cutting shaft and cutting cross tunnel to form a cutting groove, then use the cutting groove as the free surface and compensation space for backward stage full-hole lateral blasting mining, the collapsed ore is shoveled out by a scraper and poured into the middle chute, and the mine is filled and topped after the mining is completed.

[0012] Preferably, the diameter of the downward anchor hole is 90-100 mm, the hole depth is the stage height, the hole spacing is 1-2 m, the wall width is 2-3 m, and the stage height is 50-60 m.

[0013] Furthermore, when grouting the downward anchor cable hole, the grouting liquid is cement slurry, and the water-cement ratio of the cement slurry is 1:4 to 1:6.

[0014] Preferably, the width of the bar is 2 to 3 m.

[0015] Furthermore, when the filling is performed after the mining is completed in the second step, the 28-day uniaxial compressive strength of the filling body within 5 to 6 m of the top and bottom of the mining area is greater than or equal to 3 MPa.

[0016] Beneficial Effects

[0017] Compared with the existing technology and methods, the two-step stope pre-reinforcement wall protection large diameter deep hole stage empty site subsequent filling mining method provided by the present invention has the following beneficial effects:

[0018] By leaving a retaining wall, the low-quality filling body of the first-step mining area can be effectively isolated to prevent the filling body from collapsing and causing great losses and depletion. At the same time, the retained retaining wall is pre-reinforced and strengthened, and the supports of the adjacent retaining walls of the two adjacent second-step mining areas are formed into a complete whole by using vertical anchor cables and transverse reinforcements to support each other. This can effectively reduce the thickness of the retained retaining wall and increase the ore recovery rate, while also significantly improving the strength and stability of the retained retaining wall, ensuring the safety and efficiency of mining in the second-step mining area. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is further described in detail below with reference to the accompanying drawings.

[0020] Figure 1 It is a front view of a two-step stope pre-reinforcement wall protection large diameter deep hole stage empty site and subsequent filling mining method provided by the present invention;

[0021] Figure 2 A side view of a two-step stope pre-reinforcement wall protection large diameter deep hole stage empty site and subsequent filling mining method provided by the present invention;

[0022] Figure 3 A top view of a two-step stope pre-reinforcement wall protection large diameter deep hole stage empty site and subsequent filling mining method provided by the present invention;

[0023] In the figure: 1-middle transport tunnel; 2-bottom drilling tunnel; 3-mining access road; 4-protection wall; 5-vertical steel strand; 6-anchor cable construction tunnel; 7-horizontal steel strand; 8-drilling chamber; 9-column; 10-downward large-diameter deep hole; 11-one-step stope filling body. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions of various embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] Step a, defining the mining range of the second-step stope, reserving retaining walls 4 on both sides of the second-step stope to isolate the filling bodies 11 of the first-step stope on both sides, arranging anchor cable construction tunnels 6 at the boundaries of both sides of the top pillars of the second-step stope, constructing a row of downward anchor cable holes along the direction in the anchor cable construction tunnel 6, the downward anchor cable holes are located at the midline position of the reserved retaining walls 4, the diameter of the downward anchor cable holes is 90-100 mm, the hole depth is the stage height, the hole spacing is 1-2 m, the retaining wall 4 is 2-3 m wide, and the stage height is 50-60 m; constructing transverse drilling holes on the side walls of the anchor cable construction tunnel 6 to penetrate the anchor cable construction tunnel 6 of the adjacent second-step stope, the transverse drilling holes are 1.5-2 m away from the bottom plate of the anchor cable construction tunnel 6 and correspond to the positions of the downward anchor cable holes one by one;

[0026] Step b, after the construction of the downward anchor hole is completed, install the vertical steel strand 5 and the grouting pipe in the hole, the vertical steel strand 5 is exposed 1.5 to 2m from the hole mouth, and the horizontal steel strand 7 is inserted into the horizontal borehole as a horizontal reinforcement, and the horizontal steel strand 7 is exposed 2 to 3m at both ends of the borehole; then the hole bottom grouting is used to perform the hole grouting twice, and the grouting liquid is cement slurry, and the cement slurry water-cement ratio is 1:4 to 1:6. The first grouting pressure is ≥0.5 to 1.0 MPa, and the first grouting is stopped when thick cement slurry flows out of the hole mouth. The second grouting is high-pressure splitting grouting, and the second grouting is performed 3 to 5 hours after the first grouting, and the second grouting pressure is ≥1.5 to 2.0 MPa. After the second grouting is completed, it is cured for 25 to 30 days.

[0027] Step c, after the maintenance is completed, the vertical steel strands 5 in the downward anchor cable holes are tensioned, and a secondary multi-stage tensioning process is adopted. The first tensioning straightens the steel strands and stabilizes them for 20 to 30 minutes to facilitate the transmission and adjustment of the prestress in the anchor cable. The second tensioning is carried out after the prestress of the first tensioning is stabilized to compensate for the prestress loss. The total tensioning tonnage is not less than the designed tonnage. After the vertical steel strands 5 are tensioned, the vertical steel strands 5 are tensioned and connected with the corresponding transverse steel strands 7, so that the anchor cables on the adjacent side of the adjacent second-step mining site are supported by the transverse steel strands 7 in a "∩"-shaped steel strand mesh, completing the enhanced support of the reserved retaining walls 4 on both sides of the second-step mining site.

[0028] Step d, construction of the mining and cutting project, construction of the bottom rock drilling tunnel 2 at the bottom of the second step stope, which also serves as the receiving tunnel, and forms the bottom mine access 3; construction of the rock drilling chamber 8 at the top of the stope, with columns left in the rock drilling chamber 8, and the width of the column 9 is 2 to 3 meters. Then, a large-diameter deep hole 10 is constructed downward in the rock drilling chamber 8 according to the designed hole network parameters;

[0029] Step e, mining in the stope, first use the cutting skylight and cutting cross tunnel to form a cutting groove, then use the cutting groove as the free surface and compensation space to retreat and blast the full hole sideways, use the scraper to shovel out the collapsed ore and pour it into the middle chute, and fill the stope after the ore is unloaded. During the filling, the 28-day uniaxial compressive strength of the filling body within 5 to 6 meters of the top and bottom of the stope is greater than or equal to 3Mpa.

[0030] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A two-step stope pre-reinforcement wall protection large diameter deep hole stage empty site subsequent filling mining method, characterized in that The following steps are involved: Step a, delineate the mining range of the second-step stope, reserve retaining walls on both sides of the second-step stope to isolate the filling bodies of the first-step stope on both sides, arrange anchor cable construction tunnels at the boundaries of both sides of the top pillars of the second-step stope, construct a row of downward anchor cable holes along the strike in the anchor cable construction tunnel, and the downward anchor cable holes are located at the midline position of the reserved retaining walls; construct horizontal holes on the side walls of the anchor cable construction tunnel to penetrate the anchor cable construction tunnels of the adjacent second-step stopes, and the horizontal holes are 1.5 to 2 meters away from the bottom plate of the anchor cable construction tunnel and correspond to the positions of the downward anchor cable holes one by one; Step b, after the construction of the downward anchor hole is completed, a vertical steel strand and a grouting pipe are installed in the hole, the vertical steel strand is exposed 1.5 to 2m from the hole mouth, and a transverse steel strand is inserted into the transverse borehole as a transverse reinforcement, and the transverse steel strand is exposed 2 to 3m at both ends of the borehole; then the downward anchor hole is grouted twice in the form of hole bottom return, the first grouting pressure is ≥0.5 to 1.0 MPa, and the first grouting is stopped when thick cement slurry flows out of the hole mouth. The second grouting is high-pressure splitting grouting, and the second grouting is carried out 3 to 5 hours after the first grouting, and the second grouting pressure is ≥1.5 to 2.0 MPa. After the second grouting is completed, it is cured for 25 to 30 days; Step c, after the maintenance is completed, the vertical steel strands in the downward anchor cable holes are tensioned, and a secondary multi-stage tensioning process is adopted. The first tensioning straightens the steel strands and stabilizes them for 20 to 30 minutes to facilitate the transmission and adjustment of the prestress in the anchor cable. The second tensioning is carried out after the prestress of the first tensioning is stabilized to compensate for the prestress loss. The total tensioning tonnage is not less than the designed tonnage. After the vertical steel strands are tensioned, the vertical steel strands are tensioned and connected with the corresponding transverse steel strands, so that the anchor cables on the adjacent side of the adjacent two-step mining site are supported by the transverse steel strands in a "∩" shape, and the reinforced support of the reserved retaining walls on both sides of the two-step mining site is completed. Step d, construct the mining and cutting project, construct a bottom rock drilling tunnel at the bottom of the stope in step 2, which also serves as a receiving tunnel, and forms a bottom mine access; construct a rock drilling chamber at the top of the stope, leave columns in the rock drilling chamber, and then construct a large-diameter deep hole downward in the rock drilling chamber according to the designed hole network parameters; Step e, mining in the mine, first use the cutting shaft and cutting cross tunnel to form a cutting groove, then use the cutting groove as the free surface and compensation space for backward stage full-hole lateral blasting mining, the collapsed ore is shoveled out by a scraper and poured into the middle chute, and the mine is filled and topped after the mining is completed.

2. A two-step stope pre-reinforcement wall protection large diameter deep hole stage empty site subsequent filling mining method according to claim 1, characterized in that: The diameter of the downward anchor hole is 90-100 mm, the hole depth is the stage height, the hole spacing is 1-2 m, the wall width is 2-3 m, and the stage height is 50-60 m.

3. A two-step stope pre-reinforcement wall protection large diameter deep hole stage empty site subsequent filling mining method according to claim 1, characterized in that: When grouting the downward anchor cable hole, the grouting liquid is cement slurry, and the water-cement ratio of the cement slurry is 1:4 to 1:

6.

4. A two-step stope pre-reinforcement wall protection large diameter deep hole stage empty site subsequent filling mining method according to claim 1, characterized in that: The width of the bar is 2 to 3 m.

5. The two-step stope pre-reinforcement wall protection large diameter deep hole stage empty site subsequent filling mining method according to claim 1 is characterized by: When filling after the mining is completed in the second step, the 28-day uniaxial compressive strength of the filling body within 5 to 6 m of the top and bottom of the mining area is greater than or equal to 3 MPa.

Images