A method for recovering top and bottom pillars and corner residual ore in underground metal mines

Abstract

The present invention discloses a method for recovering top and bottom pillars and residual ore from corners of underground metal mines, comprising the following main steps: dividing the top and bottom pillars into strip-shaped chambers, performing two-step interval recovery, drilling rock tunnels therein, and then constructing a stope access road to connect the transport tunnel and the rock tunnel; constructing a cutting shaft in the rock tunnel, drilling upward fan-shaped medium-deep holes for blasting, using the cutting shaft and the rock tunnel as free surfaces and initial compensation space, and blasting the caving stope ore in one step; after each blasting, fresh air flows from the trackless transport tunnel through the stope access road into the stope to fully clean the working face, and then the polluted air is discharged into the main return air lane through the return air lane; after recovery is completed, the stope is sealed and backfilled to connect the top, and two-step recovery is performed. Cutting the shaft, grooving, and recovery are performed in one operation, reducing problems such as ore and rock damage and backfill damage caused by repeated operations, as well as high dilution loss rate and high safety risks; based on the use of medium-deep holes for efficient recovery, the resource recovery rate and the lowest dilution loss rate are guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of underground mining, and in particular to a method for recovering top and bottom pillars and corner residual ores in underground metal mines. Background Art

[0002] Mineral resources are non-renewable. Therefore, when mining and developing mineral resources, methods with high recovery rates should be used whenever possible. Considering the scale, safety, equipment, and personnel of mining, underground mines generally require the reservation of top and bottom pillars to ensure safety when mining the upper and lower sections simultaneously or when mining the lower section.

[0003] Conventional pillar recovery methods usually use shallow hole filling methods for mining, such as upward approach filling mining method or upward layer filling mining method, and a few use medium-deep hole subsequent filling for mining.

[0004] In the process of mining using shallow hole methods, there are usually low recovery efficiency, large mining and cutting workload, unsafe conditions, and the need for secondary reserved pillars, resulting in a low overall recovery rate.

[0005] In the mining method using medium-deep hole recovery, due to problems such as low blasting technology and poor equipment matching, the recovery safety is low and the upper filling body is damaged due to multiple blasting vibrations. The same problems and troubles exist in the recovery of residual ores. Summary of the Invention

[0006] The main purpose of the present invention is to provide a method for recovering top and bottom pillars and corner residual ores in underground metal mines with small mining and cutting workload, high recovery efficiency and high operation safety.

[0007] The method for recovering top and bottom pillars, corner and residual ore in underground metal mines provided by the present invention comprises the following main steps:

[0008] (1) Divide the top and bottom pillars into strip-shaped chambers, conduct two-step interval mining, drill rock tunnels in them, and then construct stope access roads to connect the transport level tunnels and the rock drilling level tunnels;

[0009] (2) Construct a cutting well in the rock drilling tunnel, drill a medium-deep hole in the upward fan shape for blasting, use the cutting well and the rock drilling tunnel as the free surface and initial compensation space, and blast the ore in the mining area in one go;

[0010] (3) After each blast, fresh air flows into the stope from the trackless transport tunnel through the stope access road. After fully cleaning the working face, the polluted air is discharged into the main return air tunnel through the return air level tunnel;

[0011] (4) After mining is completed, the mining area is sealed and top-filled to carry out two-step mining.

[0012] In one embodiment of the above method, the width of the first-step mine chamber is 6-8m, the width of the second-step mine chamber is 8-10m, and the height of the ore body is the full thickness of the top and bottom pillar residual ore.

[0013] In one implementation of the above method, the pillar stope is arranged vertically to the chamber stope, and the stope width is 6-10 m and the length is 20-40 m.

[0014] In one embodiment of the above method, a drilling tunnel is constructed along the center line of the stope, and a cutting tunnel is constructed at the top of the stope perpendicular to the direction of the stope, and holes are drilled in the drilling tunnel and the cutting tunnel.

[0015] In one embodiment of the above method, multiple circles of circular drill holes are constructed at the cutting well position, and the central drill hole adopts a large-diameter drill hole with a diameter of 76-90mm, and the other blast holes adopt 50-64mm. The spacing between each circle of drill holes is 300-500mm; parallel blast holes are used in the cutting groove area, and the row spacing between parallel blast holes is 1.0-1.5m. Fan-shaped blast holes are used in the normal mining area, with a diameter of 50-64mm, a row spacing of 1.3-1.5m, and a hole bottom distance of 1.6-2.0m. A distance of 0.5-1.0m must be reserved between the bottom of all blast holes and the filling body.

[0016] In one embodiment of the above method, a YGZ-90 rock drill is used to drill upward fan-shaped medium-deep holes in a flat rock tunnel.

[0017] In one embodiment of the above method, the blastholes are loaded with explosives using a charging trolley, the slot holes are detonated using double-shot digital detonators, and no detonating cord is laid in the holes; the recovery holes are detonated using single-shot millisecond difference detonating cord detonators, and detonating cords are laid in the holes, and the detonating cords in the same sections are connected.

[0018] In one embodiment of the above method, in the two-step intermittent mining, when the ore body of the first step is mined, the ore body of the second step serves as a pillar to support the roof of the mining area, the two sides of the mine room of the second step are filling bodies, the micro-difference between the blasting circles of the cutting well blastholes is 25-40ms, the micro-difference between the slot holes and the outermost circle blastholes of the cutting well is 50-75ms, and the micro-difference between the main row blastholes and the last row of slot holes is 75-100ms.

[0019] In one implementation of the above method, after blasting and ventilation, a remote-controlled scraper is used to remove the ore, and the ore is sealed and filled after removal.

[0020] In one embodiment of the above method, high-strength roof filling is used for pillar stopes, and the filling body strength is not less than 2.5MPa. For mine room stopes, low-strength filling is used, and the filling body strength is not less than 1.5Mpa.

[0021] The present invention achieves the purpose of safe and efficient mining by adopting the method of subsequent mining with medium and deep holes; adopts a rock drilling rig and a matching YT-28 drilling rig to reduce the mining and cutting work to a minimum; adopts a one-time blasting mining method to reduce the damage to the upper filling body caused by repeated charging and blasting vibration, as well as the safety hazards in the charging process; adopts remote control trolleys, charging trolleys, rock drilling trolleys and other mechanical equipment to reduce the input and participation of personnel in the whole process as much as possible; by improving the strength of the filling body at the top and bottom of the mining area, adjusting the mining direction of residual ore resources, and achieving the purpose of ensuring the safety of the entire mining process. In short, the present invention has the following advantages: well cutting, grooving, and mining are performed in one operation, reducing the problems of ore and rock damage and filling body damage caused by repeated operations, high depletion loss rate, and high safety risks; on the basis of using medium and deep holes for efficient mining, it ensures the resource recovery rate and the lowest depletion loss rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the plan layout of an embodiment of the present invention.

[0023] Figure 2 for Figure 1 Schematic diagram of Ⅱ-Ⅱ in .

[0024] Figure 3 Schematic diagram of the blast hole charging structure in this embodiment.

[0025] Figure 4 Schematic diagram of the slotted blasthole arrangement and detonation sequence in this implementation.

[0026] Figure 5 Schematic diagram of the arrangement of mining blastholes and the detonation sequence in this embodiment.

[0027] Figure 6 This is a schematic diagram of the blasting network connection in this embodiment.

[0028] The serial numbers in the figure are: 1-cutting well area; 2-cutting groove area; 3-large diameter empty hole; 4-positive row mining area; 5-cutting groove blast hole; 6-cutting well blast hole; 7-cutting cross road; 8-connecting road; 9-upper filling body; 10-ore body boundary; 11-positive row blast hole; 12-rock drilling level road; 13-blast hole collapse range. DETAILED DESCRIPTION

[0029] The method disclosed in the present invention for recovering top and bottom pillars and residual ore from corners of underground metal mines is applied to the recovery blasting design of the Sh-320mS9# bottom pillar stope of the Fankou Lead-Zinc Mine. The stope is located between the control lines X191 and X200, with a width of 9m and a length of 20.6m. The ore volume is 3800t. The upper, lower and both sides of the stope have been recovered and filled. At present, the medium-deep hole of the S9# bottom pillar has been constructed. The fan-shaped medium-deep hole is used for recovery, and the 3m 3The ore is unloaded by a remote-controlled scraper. The designed depletion rate is 12% and the loss rate is 2%. The geological overview is as follows:

[0030] The orebody is primarily composed of pyrite, lead, and zinc, with some pyrite. The strata are the D3ta and D3tb formations of the Upper Devonian Tianziling Formation, the downward pressured formations. Within these formations lies the northeast-trending F3 major fault and secondary minor faults. The D3ta and D3tb formations are structurally well-developed, prone to delamination and flaking, resulting in poor integrity. The orebody exhibits poor structure and structural development, prone to spalling and caving. Furthermore, the orebody is complex in morphology, with numerous branching and complex formations.

[0031] like Figures 1 to 6 As shown, the specific process of mining in this embodiment is as follows:

[0032] The pillar is divided into strip-shaped chambers, and mining is carried out in a two-step, intermittent manner. The first chamber is 8m wide, and the second chamber is 7m wide. The ore body height is the full thickness of the pillar residual ore (generally 8m). The pillar stope is arranged perpendicular to the chamber stope, with a width of 6-10m and a length of 20-40m. During mining, a YGZ-90 rock drill drills upward-facing, fan-shaped, medium-deep holes in the drilling lanes. Charges are loaded using a charging trolley. Cutting shafts are pre-constructed in the stopes. Mining blasting is carried out using medium-deep hole blasting, with the cutting shafts and drilling lanes serving as the free surface and initial compensation space. The ore in the stope is caving in a single blast. Mining of the ore body is carried out below the top plate of the backfill. To ensure operational safety, remote-controlled scrapers are used to remove the ore, and personnel are not allowed to enter the open area. After mining is completed, the stope is sealed and the backfill is connected to the roof. This mining method is fully mechanized. In two-step interval mining, when the first-step ore body is mined, the second-step ore body serves as a pillar to support the stope roof, and the two sides of the second-step mine room are filled with filling. Figure 1 The upper backfill area is staggered with the upper backfill area, and the upper backfill strength is required to be ≥4MPa. A thickness of 0.5-1.0m is reserved between the blasthole and the upper backfill area to maximize the safety of the medium and deep hole backfill and the depletion loss rate during the mining process.

[0033] Mining preparation primarily involves the entry of the stope and the drilling of horizontal tunnels; cutting primarily involves cutting horizontal tunnels. The stope is entered by driving the entry (3.0m x 3.0m) through the original segmented tunnels. After the entry is completed, a drilling tunnel (3.2m x 3.2m) is driven through the center of the mine room, passing through the return air tunnel. In stopes with good ore body stability, the sides of the drilling tunnel can be expanded and the roof can be raised, leaving side pillars to increase the drilling chamber space.

[0034] After the mining and cutting work is completed, the stope recovery operation is carried out, and the cutting well is formed by medium-deep hole blasting. The cutting well is used as the free surface and initial compensation space to blast the collapsed ore in one go.

[0035] A YGZ-90 drilling rig was used to construct medium-long holes with a diameter of 60 mm. Hole pattern parameters: The cutting tunnel was located at the eastern end of the drilling tunnel and extended toward the sides of the stope, revealing the backfill. The cutting tunnel was 3.0 m wide and 3.0 m high. Upward parallel medium-long holes were used for slotting, using diagonal blasting. Four empty holes were arranged as compensation space. The slotting area used upward parallel medium-long holes measuring 1.2 m by 1.2 m. The side blasting area used a fan-shaped medium-long hole arrangement with a row spacing of 1.3 m, a hole bottom distance of 1.6 m, a row face orientation of 0°, and an angle of 80° between the row face and the horizontal plane. A distance of 0.5-1.0 m was required between the bottom of each blasthole and the backfill.

[0036] On both sides of the rock tunnel, where medium- and deep-hole drilling is not feasible, a YT-28 drilling rig is used to drill 1.0-1.5m side holes until the filling is visible. For mining, inclined medium- and deep-holes are drilled until the filling is visible, and a exploratory hole is drilled in each row of slotting holes until the filling is visible.

[0037] The 4th and 5th holes in the 18th and 19th rows of gun holes must penetrate the bottom plate of the first section of the approach.

[0038] There are 19 rows of fan-shaped medium-long hole blasting holes for mining, with a total length of 189 holes and a total length of 612.1m. There are 64 medium-long holes parallel to the upper groove, with a total length of 198.4m. Figure 1 、 Figure 2 and Figure 4 、 Figure 5 .

[0039] According to actual measurements, there are a total of 64 deep holes in the medium-deep holes in the cutting slots of the mining area and the medium-deep holes in the fan-shaped mining area, 10 medium-deep holes in 2 rows of mining area and 4 shallow-eye filling holes, 10 medium-deep holes in 3 rows of mining area and 4 shallow-eye filling holes, and the construction of all blastholes basically meets the design requirements.

[0040] Based on actual measurements, the medium-long holes in the stope cutting slots and the medium-long holes in the recovery sector were 64 in total, totaling 210 meters in length. The recovery holes consisted of 204 medium-long blastholes in 19 rows, totaling 554.7 meters in length. A total of 70 shallow-hole supplementary holes were drilled, and all blasthole construction essentially met design requirements. Partial medium-long holes in the 18th and 19th rows penetrated a section of the roadway and required plugging before charging. Measured blasthole data indicated that the hole bottom spacing and row spacing, with slight deviations, met design requirements.

[0041] The slot holes are detonated with double millisecond difference nonel detonators, and no detonating cord is laid in the holes; the mining holes are detonated with single millisecond difference nonel detonators, and detonating cord is laid in the holes. The detonating cords between the same sections are connected. All the charges are loaded to the bottom of the hole, and the depth of the charge surface from the hole mouth is 1-2m. No charge is controlled in shallow holes, and the hole mouth is blocked with gun mud. Figure 3 .

[0042] The detonation is carried out using a nonel-nonel detonation network. All nonel tubes in the hole are connected to the blasting detonator (each bundle of nonel tubes cannot exceed 20 tubes). The detonation is carried out using two ordinary nonel detonators, which are detonated by a detonator. The detonation sequence of the slotted blasthole is shown in the following table. Figure 4 , the order of blasting the mining holes is shown in Figure 5 .

[0043] The top and bottom pillar stopes are blasted throughout the stope, with the cut slots serving as the free surface. Small charging trolleys are used to load mining emulsion explosives, with a unit explosive consumption of 0.3-0.4 kg / t and a packing length of 1.0-1.5 m. Slot holes are detonated with double-shot millisecond-delay detonators, without detonating cords installed. Stope holes are detonated with single-shot millisecond-delay detonators, with detonating cords installed within the holes, connecting the detonating cords within the same section. The detonation system utilizes a detonating cord-to-detonating cord system.

[0044] Charge per meter of blasthole:

[0045] q=π×r 2 ×l×ρ

[0046] =3.14×9.6cm2×100cm×1.0g / cm3×1kg / 1000g=3.01kg

[0047] The charge density is 1.2g / cm 3 According to the formula, the charge per meter of blasthole is 3.01kg. The amount of ore blasted this time is 1014.4m 3 The compensation space volume is 1249.7m 3 , the compensation space coefficient is 1.23. The blasting volume is about 3800t, requiring 1800kg of emulsion explosives, with a unit explosive consumption of 0.47kg / t. The slot holes are detonated with double millisecond difference detonating cord detonators, and no detonating cord is laid in the holes; the mining holes are detonated with single millisecond difference detonating cord detonators, and detonating cords are laid in the holes, with detonating cords connected between the same sections. See for details. Figure 6 324 millisecond delay detonators, detonating cord auxiliary detonation, 160 pieces of 4.5m / piece detonating cord, 20 pieces of 6.5m / piece detonating cord, and 120kg of rolled emulsion explosive.

[0048] The on-site explosive charge for blasting in the mining area was 1,820 kg. The mining area settlement data showed 2,704 tons of ore, 305 tons of waste rock, and a depletion rate of 10.1%.

[0049] After each blasting, fresh air flows into the mine through the trackless transport tunnel and the mine access road. After fully cleaning the working face (ventilation time is not less than 40 minutes), the polluted air is discharged into the main return air tunnel through the return air level tunnel.

[0050] After ensuring good ventilation, a remote-controlled scraper is used to transport the ore to the chute; after the collapsed ore is removed, the next cycle of operation will be carried out. When the bottom pillar mining area is relatively long or the bottom pillar is relatively broken, mining will be stopped after a certain length, and the mined area will be filled with formwork to control the ground pressure and safely mine the remaining ore.

[0051] Note that this embodiment requires that when filling the normal mining area, the strength of the top and bottom filling bodies must be strictly ≥4MPa and the thickness must be ≥6m, or the filling strength and thickness must be used in the empty area close to the residual ore.

Claims

1. A method for recovering top and bottom pillars, corner and residual ore in an underground metal mine, comprising the following steps: (1) Divide the top and bottom pillars into strip-shaped chambers, carry out two-step interval mining, drill rock tunnels in them, and then construct stope access roads to connect the transport level tunnels and the rock drilling level tunnels; (2) Construct a cutting well in the rock drilling tunnel, drill an upward fan-shaped medium-deep hole for blasting, use the cutting well and rock drilling level tunnel as the free surface and initial compensation space, and blast the ore in the mine in one go; (3) After each blast, fresh air flows into the stope from the trackless transport tunnel through the stope access road. After fully cleaning the working face, the polluted air is discharged into the main return air tunnel through the return air level tunnel; (4) After the mining is completed, the stope is sealed and top-filled, and the second step of mining is carried out; The width of the first-step mine chamber is 6-8m, the width of the second-step mine chamber is 6-10m, and the height of the ore body is the full thickness of the top and bottom pillar residual ore; Construct rock drilling tunnels along the center line of the stope, and construct cutting tunnels perpendicular to the direction of the stope at the top of the stope, and construct drilling holes in the rock drilling tunnels and cutting tunnels; Multiple circles of circular boreholes are constructed at the cutting well location, with the center hole using a large-diameter borehole of 76-90mm, and other blastholes using 50-64mm. The spacing between each circle of boreholes is 300-500mm. Parallel blastholes are used in the cutting groove area, with a row spacing of 1.0-1.5m between parallel blastholes. Fan-shaped blastholes are used in the normal mining area, with a hole diameter of 50-64mm, a row spacing of 1.3-1.5m, and a hole bottom distance of 1.6-2.0m. A distance of 0.5-1.0m must be reserved between the bottom of each blasthole and the backfill. In two-step interval mining, when the first-step ore body is mined, the second-step ore body serves as a pillar to support the mining area roof. The two sides of the second-step mine room are filling bodies. The micro-difference between the blasting circles of the cutting well blastholes is 25-40ms, the micro-difference between the slot holes and the outermost circle blastholes of the cutting well is 50-75ms, and the micro-difference between the main row blastholes and the last row of slot holes is 75-100ms.

2. The method according to claim 1, wherein: The pillar stope is arranged vertically to the mine room stope, with a width of 6-10m and a length of 20-40m.

3. The method according to claim 1, wherein: A YGZ-90 rock drill is used to drill upward fan-shaped medium-deep holes in the rock drilling tunnel.

4. The method according to claim 1, wherein: The blast holes are loaded with explosives using charging trolleys, the slot holes are detonated using double-shot digital detonators, and no detonating cord is laid in the holes; the recovery holes are detonated using single-shot millisecond difference detonating cord detonators, and detonating cords are laid in the holes, and the detonating cords in the same sections are connected.

5. The method according to claim 1, wherein: After blasting and ventilation, a remote-controlled scraper is used to remove the ore, which is then sealed and filled.

6. The method according to claim 5, wherein: For pillar mining areas, high-strength top filling is adopted, and the filling body strength is not less than 2.5MPa. For room mining areas, low-strength filling is adopted, and the filling body strength is not less than 1.5MPa.

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