A method for recovering top pillars by combined blasting of pre-splitting blastholes and radial blastholes

Abstract

A method for recovering a top column by blasting a combination of pre-splitting blastholes and radial blastholes at intervals comprises the following steps: (1) determining the length of the top column to be recovered in blocks according to the width of the top column; (2) excavating a connecting road from a pedestrian ventilation shaft in the intermediate column to the surrounding rock of the lower wall, and excavating a top column blasting and rock drilling tunnel parallel to the top column at the end of the connecting road; (3) excavating a top column pre-splitting hole and radial blastholes in the top column blasting and rock drilling tunnel; (4) first blasting the top column pre-splitting blasthole to produce pre-cracks, and then blasting the radial blastholes in blocks at intervals to recover the top column, and after blasting, the upper segmented waste rock falls into the mining field to fill the empty area of ​​the mining field. Compared with the traditional top column recovery method, the present invention has safe construction operations, controllable recovery process, low ore block rate, and high top column recovery rate.

Description

Technical Field

[0001] The invention relates to the field of blasting recovery of stope top pillars, in particular to a method for recovering top pillars by combined blasting of pre-splitting blastholes and radial blastholes. Background Art

[0002] Traditional open-pit mining methods are widely used in underground mining of metal mines due to their simple structure, high recovery rate, low dilution rate and loss rate. However, the top pillar recovery of open-pit mining methods is relatively difficult, and the large-scale blasting during the recovery process is difficult to control.

[0003] The traditional open-field method usually uses horizontal bundles of medium-to-deep holes for top pillar drilling, and the entire top pillar is recovered in one blast. This recovery method results in a high rate of large blasting blocks, and a single large-scale blast makes the blasting process and blasting results difficult to control. The top pillar ore dropped by the blasting is difficult to be unearthed and recovered through a funnel or a shovel loader.

[0004] Through the combination of pre-splitting blastholes and radial blastholes, blastholes are drilled in blocks, blasted in blocks, and top pillars are recovered at intervals. The main implementation steps are: first determine the length of each cycle of blasting; then drill the connecting road and the top pillar blasting rock drilling tunnel, then drill pre-splitting blastholes and radial blastholes in the top pillar blasting rock drilling tunnel, and finally implement pre-splitting blasting to produce pre-cracks, so that the top pillar is divided into blocks, and then block recovery blasting is carried out to complete the ore dropping and recovery of the top pillar. According to the cycle of "pre-splitting blasting-block recovery blasting-pre-splitting blasting-...", the top pillar can be recovered in a controllable manner at intervals. Summary of the invention

[0005] The purpose of the present invention is to provide a method for recovering top pillars by blasting a combination of pre-splitting blastholes and radial blastholes at intervals. The method combines the pre-splitting blastholes with the radial blasthole arrangement, firstly pre-splitting blasting is used to create pre-cracks, and then the top pillars are recovered by blasting in blocks at intervals.

[0006] After the ore recovery in the mining area is completed and the goaf is processed, blasting to recover the top pillar begins. To ensure a controllable process, the length of the top pillar recovered in each cycle of blasting is controlled by controlling the spacing between adjacent pre-splitting blastholes. Usually, the length recovered in each cycle is 1 / 4 to 1 / 5 of the total length of the top pillar. Pre-cracks are created by pre-splitting blasting to provide a free surface for subsequent blasting; then radial blastholes are blasted to control the top pillar in controlled blocks. The amount of blasted ore recovered by the top pillar and the blasting quality are controlled through the cycle of "pre-splitting blasting-block blasting".

[0007] The technical solution adopted by the present invention is: a method for recovering the top column by blasting a combination of pre-splitting blastholes and radial blastholes at intervals, comprising the following steps:

[0008] (1) Determine the length of the top column for block recovery

[0009] The length of the top pillar to be recycled in each cycle is determined based on the width of the top pillar. When the width of the top pillar is less than or equal to 4m, 1 / 4 of the total length of the top pillar is recycled in each cycle; when the width of the top pillar is greater than 4m, 1 / 5 of the total length of the top pillar is recycled in each cycle;

[0010] (2) Excavation of connecting roads and top pillar blasting rock drilling tunnels

[0011] From the pedestrian ventilation shafts in the pillars on both sides of the stope, connecting roads are excavated to the lower wall respectively. From the ends of the two connecting roads, top pillar blasting and rock drilling tunnels are excavated parallel to the ore body, and the top pillar rock drilling tunnel is ensured to be at least 5m away from the top pillar;

[0012] (3) Drilling pre-crack holes and radial blast holes

[0013] Pre-splitting blastholes are drilled toward the top pillar in the top pillar blasting drilling tunnel, and the spacing between the two rows of top pillar pre-splitting blastholes is the same as the length of the top pillar recovered in each cycle; radial medium-deep holes are drilled between the two rows of pre-splitting blastholes in the top pillar blasting drilling tunnel, and the distance between the bottom of the blastholes of the medium-deep holes is less than the spacing between the blastholes during large-scale blasting of the ore body, and the angle between the blasthole radiation angle and the horizontal plane ranges from 0° to 60°;

[0014] (4) Top pillar pre-splitting blasting and top pillar block blasting

[0015] Pre-splitting blasting is used to create pre-cracks, providing a structural surface for subsequent radial hole blasting, and the blastholes used for pre-splitting blasting are charged and sealed at intervals; adjacent blastholes serve as guiding holes for each other, so that the stress waves formed by the blasting meet between the two holes, and tensile stress appears in the rock mass along the direction of the pre-splitting hole, resulting in pre-cracks; all pre-splitting blasting charged blastholes use uncoupled charging to reduce the blasting pressure of the explosives on the blasthole wall; all pre-splitting blastholes are detonated at one time to shorten the detonation error of the pre-splitting holes and ensure the seam-forming effect of the pre-splitting blasting. After the pre-splitting blasting, radial hole blasting is carried out to recover the top pillar, and the radial blastholes are charged within the length of the ore body, and no charge is charged within the length of the surrounding rock and only sealed; millisecond differential blasting is used for radial hole blasting.

[0016] The specification of the connecting channel in step (2) is 2.5×2m 2 The specifications of the top pillar blasting rock drilling tunnel are 3×2.8m 2 .

[0017] The length of the pre-splitting blastholes in step (3) is 8 to 18 m, the number of pre-splitting blastholes in each row is 3 to 15, the length of the radial medium-deep holes is 8 to 25 m, the number of radial medium-deep holes in each row is 6 to 18, and the hole bottom distance is 0.8 to 2.0 m.

[0018] The uncoupled charge coefficient in step (4) is 2 to 5, the blast hole plugging is made of polyurethane, ore powder or clay material, and the millisecond difference blasting delay time is 10 to 60 ms.

[0019] The outstanding advantages of the present invention are:

[0020] (1) This blasting method can recover the top pillar in a controlled manner at each distance, thus reducing the probability of accidents caused by large-scale blasting;

[0021] (2) Block blasting can reduce the large block rate of the top pillar and improve the recovery rate of the top pillar ore;

[0022] (3) While recovering the top pillar, the waste rock from the upper section falls into the empty area, which can control the ground pressure;

[0023] (4) Construction work is safe, all processes are carried out in the pillars or the surrounding rock of the footwall, and personnel do not enter the empty area of ​​the stope;

[0024] (5) Combine traditional pre-splitting and radial hole drilling and blasting technologies to achieve new engineering goals and make the traditional technology combination produce a better overall effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a stereoscopic diagram of the method for recovering top pillars at intervals by combined blasting of pre-splitting blastholes and radial blastholes according to the present invention.

[0026] Figure 2 This is a cross-sectional view of the method for recovering the top column at a distance by blasting a combination of pre-splitting blastholes and radial blastholes according to the present invention.

[0027] Figure 3 This is a cross-sectional view II-II of the method for recovering top pillars at intervals by combined blasting of pre-splitting blastholes and radial blastholes according to the present invention.

[0028] Figure 4 This is a blasthole arrangement diagram for recovering top pillars at intervals by blasting a combination of pre-splitting blastholes and radial blastholes according to the present invention.

[0029] Marked in the figure are: top pillar blasting rock drilling tunnel 1; top pillar pre-splitting blasthole 2; top pillar blasting radiation blasthole 3; unblasted top pillar 4; upper stage waste rock 5; connecting road 6; pedestrian ventilation shaft 7; intermediate pillar 8; mining area 9; pre-splitting blasting hole 10; blasting equipotential surface 11. DETAILED DESCRIPTION

[0030] Taking the chamber method of the staged rock drilling of a steeply inclined medium-thick ore body in a mine as an example, the length of the chamber top column is 50m, the width is 10m, and the thickness is 8m. The technical solution of the present invention is further described through drawings and examples.

[0031] like Figures 1 to 4 As shown, this embodiment is an example of the method for recovering the top column by blasting the pre-splitting blasthole and the radial blasthole combination according to the present invention, comprising the following steps:

[0032] (1) The width of the steeply inclined medium-thick roof pillar is 10 m, the length of the mine room is 50 m, and 1 / 5 of the total length of the roof pillar, i.e. 10 m, is recovered in each cycle;

[0033] (2) From the pedestrian ventilation shaft 7 in the pillars 8 on both sides of the stope, dig 2.5×2m to the lower wall 2 Connecting Road 6, excavate 3×2.8m parallel to the ore body from the end of connecting road 6 2 Top pillar blasting rock drilling tunnel 1, and ensure that the top pillar rock drilling tunnel is more than 5m away from the top pillar;

[0034] (3) First, in the top pillar blasting drilling tunnel 1, pre-splitting holes 2 are drilled toward the top pillar 4. The number of blast holes in each row of pre-splitting blasting is 13, and the distance between the bottom of the pre-splitting blast holes is 1.8m; the spacing between the two rows of pre-splitting blast holes is the same as the total length of the top pillar recovered in each cycle, which is 10m. Secondly, in the top pillar blasting drilling tunnel 1, radial medium-depth holes 3 are drilled between the two rows of pre-splitting blast holes, with a total of 6 blast holes in each row and a total of 13 rows in each cycle; the distance between the bottom of the radial blast holes is 1.4m, and the angle between the blast hole radiation angle and the horizontal plane ranges from 0° to 60°;

[0035] (4) Pre-splitting blasting to create pre-cracks. The pre-splitting holes are charged at intervals, i.e., the top column pre-splitting hole 2 is charged, and the pre-splitting blasting empty hole 10 is not charged. The empty hole 10 blasted without charge is the guide empty hole of the top column pre-splitting hole 2. All pre-splitting blasting charged holes use uncoupled charges, and the uncoupling coefficient is 2; all pre-splitting holes with charges are detonated at one time.

[0036] After the pre-splitting blasting is completed, the top pillar radial blastholes 3 are blasted and the top pillars 4 are recovered. The radial blastholes 3 are charged within the length of the ore body, and the surrounding rock length is not charged and sealed with polyurethane. The bottom two rows of radial blastholes 2 are blasted first, followed by the middle two rows of blastholes, and finally the top two rows of blastholes. The radial blastholes 3 recovered by the top pillars are blasted using millisecond micro-difference blasting, with an interval of 20ms and a total blasting time of 60ms. An equipotential surface 11 is formed during the blasting process. After the top pillars are blasted in blocks, the upper stage waste rock 5 falls from the blasted top pillar part, realizing the recovery of the top pillars at a distance and filling the empty area 9 of the mining area.

[0037] Steps (4) and (5) are repeated until the top pillar in a mine room is mined out.

Claims

1. A method for recovering the top column by blasting a combination of pre-splitting blastholes and radial blastholes at intervals. Its characteristics are: The following steps are involved: (1) Determine the length of the top column for block recovery The length of the top pillar to be recycled in each cycle is determined based on the width of the top pillar. When the width of the top pillar is less than or equal to 4m, 1 / 4 of the total length of the top pillar is recycled in each cycle; when the width of the top pillar is greater than 4m, 1 / 5 of the total length of the top pillar is recycled in each cycle; (2) Excavation of connecting roads and top pillar blasting rock drilling tunnels From the pedestrian ventilation shafts in the pillars on both sides of the stope, connecting roads are excavated to the lower wall respectively. From the ends of the two connecting roads, top pillar blasting and rock drilling tunnels are excavated parallel to the ore body, and the top pillar rock drilling tunnel is ensured to be at least 5m away from the top pillar; (3) Drilling pre-crack holes and radial blast holes Pre-splitting blastholes are drilled toward the top pillar in the top pillar blasting drilling tunnel, and the spacing between the two rows of top pillar pre-splitting blastholes is the same as the length of the top pillar recovered in each cycle; radial medium-deep holes are drilled between the two rows of pre-splitting blastholes in the top pillar blasting drilling tunnel, and the distance between the bottom of the blastholes of the medium-deep holes is less than the spacing between the blastholes during large-scale blasting of the ore body, and the angle between the blasthole radiation angle and the horizontal plane ranges from 0° to 60°; (4) Top pillar pre-splitting blasting and top pillar block blasting Pre-splitting blasting is used to create pre-cracks, providing a structural surface for subsequent radial hole blasting, and the blastholes used for pre-splitting blasting are charged and sealed at intervals; adjacent blastholes serve as guiding holes for each other, so that the stress waves formed by the blasting meet between the two holes, and tensile stress appears in the rock mass along the direction of the pre-splitting hole, resulting in pre-cracks; all pre-splitting blasting charged blastholes use uncoupled charging to reduce the blasting pressure of the explosives on the blasthole wall; all pre-splitting blastholes are detonated at one time to shorten the detonation error of the pre-splitting holes and ensure the seam-forming effect of the pre-splitting blasting. After the pre-splitting blasting, radial hole blasting is carried out to recover the top pillar, and the radial blastholes are charged within the length of the ore body, and no charge is charged within the length of the surrounding rock and only sealed; millisecond differential blasting is used for radial hole blasting.

2. The method for recovering the top column by blasting the pre-splitting blasthole and the radial blasthole combination according to claim 1, Its characteristics are: The specification of the connecting channel in step (2) is 2.5×2m 2 The specifications of the top pillar blasting rock drilling tunnel are 3×2.8m 2 .

3. The method for recovering the top column by blasting the pre-splitting blasthole and radial blasthole combination according to claim 1, Its characteristics are: The length of the pre-splitting blastholes in step (3) is 8 to 18 m, the number of pre-splitting blastholes in each row is 3 to 15, the length of the radial medium-deep holes is 8 to 25 m, the number of radial medium-deep holes in each row is 6 to 18, and the hole bottom distance is 0.8 to 2.0 m.

4. The method for recovering the top column by blasting the pre-splitting blasthole and the radial blasthole combination according to claim 1, Its characteristics are: The uncoupled charge coefficient in step (4) is 2 to 5, the blast hole plugging is made of polyurethane, ore powder or clay material, and the millisecond difference blasting delay time is 10 to 60 ms.

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