A method for setting up and blasting boreholes in deep open-pit mine ore passes.

Abstract

This invention discloses a method for setting up and blasting boreholes in the deep ore pass of an open-pit mine, comprising the following steps: 1) Setting up boreholes, shaping boreholes, buffer boreholes, and main blasting boreholes sequentially outward from the horizontal ore pass opening before the blasting; 2) The downslope boreholes are the first ring of boreholes set along the edge of the ore pass opening; 3) The shaping boreholes are the second ring of boreholes adjacent to the downslope boreholes; 4) The buffer boreholes are the third ring of boreholes located between the shaping boreholes and the main blasting boreholes; 5) The main blasting boreholes are the fourth ring of boreholes adjacent to the buffer boreholes, with a single borehole charge of 210-220 kg. The blasting of the ore pass downslope is carried out in the order of detonation of the downslope boreholes, shaping boreholes, main blasting boreholes, and buffer boreholes. The beneficial effects of this invention are: it can minimize the vibration and impact damage during the blasting of the ore pass opening and its surrounding boreholes, thus ensuring the integrity and stability of the surrounding rock of the ore pass.

Description

Technical Field

[0001] This invention relates to the field of blasting technology in open-pit mining engineering, specifically to a method for setting up blasting boreholes and blasting methods for descending sections of deep open-pit mine ore passes. Background Technology

[0002] Advance ore pass development is the most common development method in open-pit mines, establishing transportation channels from various mining levels in the open-pit area to industrial sites such as the surface crushing station. Deep open-pit ore passes typically refer to vertical storage ore passes with a depth exceeding 100m and a diameter exceeding 5m. Lowering blasting of open-pit ore passes refers to blasting operations that lower the ore pass opening by one bench height along with the open-pit mining project. Each ore pass must undergo 1-2 lowering blasting operations before the completion of the upper bench mining (one blast per bench for full lowering, and two blasts per bench for half-wall lowering). Descending blasting in ore passes is a challenging and crucial engineering blasting technique. The success of the blasting directly affects the smooth operation of the ore pass and subsequent processes. Although many mine blasting technicians in China are continuously exploring new methods for descending blasting in ore passes, no effective and referable technical experience has yet been formed. After descending blasting, there are common problems such as the ore pass opening diameter increasing due to collapse and blockage accidents caused by large pieces of collapsed rock entering the ore pass.

[0003] Currently, the mining area has four deep ore passes, each designed with a diameter of 6 meters. Due to wear and tear from long-term operation, their actual diameters now exceed 8 meters. Specifically: Passes #1 and #2 were put into operation during the initial construction phase; Pass #1 has a current depth of 140 meters, and Pass #2 has a depth of 152 meters. Passes #3 and #4 were built and put into operation in 2014, and their current depths are both 382 meters. Each pass experiences extremely poor operation for approximately one month after each blasting section, frequently resulting in production accidents where large pieces of rock fragments enter the pass and block the ore outlet. This problem is particularly severe in Passes #3 and #4, which have fractured surrounding rock and have undergone four blasting sections for blasting, where the diameter of the pass opening has increased and the blockage problem has become increasingly serious. Currently, all four passes are in an "elliptical funnel-shaped" state, with the slope angle of the shaft wall in the blasting section exceeding 50 degrees. ° ~72 ° Between these measurements, the upper opening length of each ore pass exceeded 22m and the width exceeded 15m. The cross-section of the well wall at the new level (referred to as the "theoretical lower opening") was approximately 8-10m long and 7-9m wide. If the existing blasting technology for lowering the ore pass is continued, there is a high probability of major accidents such as the inability to install the new ore pass screen and the blockage of the ore pass by large pieces of ore. From a blasting technology perspective, the main reason for the deterioration of the stability of the ore pass after the lowering blasting is the unreasonable design of parameters such as the arrangement of blast holes, the over-depth value, the base resistance line, the charge structure, the micro-delay detonation time, and the throwing direction. The excessive amount of explosive charge at the bottom of the hole increases the blasting vibration and impact damage around the ore pass wall. Summary of the Invention

[0004] The purpose of this invention is to provide a simple and easy-to-operate method for the layout and blasting of blast holes in deep open-pit mine ore passes. This method employs a gas-spaced, radially decoupled, and segmented charge structure with micro-delay detonation technology for each blast hole, which makes the distribution of explosives at the bottom of each blast hole more dispersed and minimized. This method can minimize the vibration and impact damage during blasting of the ore pass and its surrounding blast holes, and ensure the integrity and stability of the surrounding rock of the ore pass.

[0005] The present invention provides a blasting hole for descending sections in a deep open-pit mine ore pass, comprising a descending section hole 1, a shaping hole 2, a buffer hole 3, and a main blasting hole 4;

[0006] The descending hole 1 includes a plugging section I101 and a charge cartridge I102. The charge cartridge I102 is fixedly connected to the bottom surface of the plugging section I101. The charge capacity of a single hole is 55-60 kg. The function of the descending hole 1 is to lower the height of the horizontal chute 13 before the descending blast by one stage after detonation. The chute is lowered by 12 m, forming a new horizontal chute with a platform of 1-1.5 m in edge contour and width.

[0007] The shaping hole 2 includes a filling section II 201 and a charge cartridge II 202. The bottom surface of the filling section II 201 is fixedly connected to the charge cartridge II 202. The charge capacity of a single hole is 55-60 kg. The shaping hole 2 mainly serves to widen the working platform of the horizontal chute 14 after the descending blast. After detonation, it can form a stable platform 4-5 m wide around the horizontal chute 14 after the descending blast.

[0008] The buffer hole 3 includes a first filling section 301, a first drug roll section 302, a second filling section 303, a second drug roll section 304, and a gas spacer II 305. The bottom surface of the first filling section 301 is connected to the first drug roll section 302, the bottom surface of the first drug roll section 302 is connected to the second filling section 303, the bottom surface of the second filling section 303 is connected to the second drug roll section 304, and the bottom surface of the second drug roll section 304 is provided with a gas spacer II 305. The first drug roll section 302 and the second drug roll section 304 form a secondary drug column 12, with a single hole drug loading capacity of 115-120 kg.

[0009] The main blast hole 4 includes a plugging section 8, a gas spacer I 9, and a main explosive charge 10. The bottom surface of the plugging section 8 is provided with a gas spacer I 9, and the bottom surface of the gas spacer I 9 is connected to the main explosive charge 10. The charge per hole is 210-220 kg, and the explosive charge in one blast is 50,000-60,000 tons. After the blast pile is loaded, a transportation operation platform with a width of more than 15m can be formed around the horizontal chute opening 14 after the descending blast.

[0010] The diameter of the descending hole 1 is 90mm, the inclination angle α1 of the descending hole 1 is 60°~80°, the depth of the descending hole 1 is 12.5m, of which the extra depth is 0.5m, and the number of descending holes 1 is 21-23.

[0011] The diameter of the shaping hole 2 is 90mm, the inclination angle α2 of the shaping hole 2 is 65°~85°, the depth of the shaping hole 2 is 13m, of which the extra depth is 1.0m, and the number of shaping holes 2 is 21-23.

[0012] The buffer hole 3 has a diameter of 200mm and is a vertical blast hole. The blast hole depth of the buffer hole 3 is 13.5m, of which the extra depth is 1.5m. The number of buffer holes 3 is 15-17.

[0013] The main blast hole 4 has a diameter of 200mm, is a vertical blast hole, and has an extra depth of 2-2.5m. The number of main blast holes 4 is 57-59.

[0014] A method for laying out blasting holes in a deep open-pit mine ore pass for descending sections includes the following steps:

[0015] 1) Along the horizontal chute opening 13 before the blasting of the descending section, descending section hole 1, shaping hole 2, buffer hole 3, and main blasting hole 4 are arranged outward in sequence;

[0016] 2) The descending section hole 1 is the first ring of blast holes arranged along the edge of the chute opening;

[0017] 3) The shaping hole 2 is the second ring of blast holes immediately adjacent to the descending section hole 1;

[0018] 4) The buffer hole 3 is the third ring of blast holes located between the shaping hole 2 and the main blast hole 4;

[0019] 5) The main blast hole 4 is the fourth ring of blast holes adjacent to the buffer hole 3.

[0020] A blasting method for descending blasting holes in a deep open-pit mine ore pass includes the following steps: The descending blasting network is designed with descending holes 1, shaping holes 2, main blasting holes 4, and buffer holes 3 in the detonation sequence. Descending holes 1 are detonated in two paths with slight delays, one descending hole 1 is selected as the detonation point, and the slight delay times for adjacent descending holes 1 on both sides are 20ms and 30ms respectively. Other adjacent descending holes 1 are detonated with a slight delay of 20ms. The first shaping hole 2 to be detonated has a delay time set to 65ms, and is detonated in two paths with slight delays, one on the left and one on the right. The delay times for the two shaping holes 2 adjacent to the first detonated hole are 85ms and 95ms respectively. Other adjacent shaping holes 2 are detonated with a slight delay of 20ms. The detonation time is ms; the main detonation holes 4 are detonated one by one in the order from the front row main detonation holes 4 to the back row main detonation holes 4. The delay time of the first detonating main detonation hole 4 is 130ms, the micro-difference time between adjacent main detonation holes 4 is 25ms, and the micro-difference time between rows is 65ms; the buffer hole 3 is detonated with a micro-difference time 25ms later than the adjacent main detonation hole 4.

[0021] When the descending hole 1 and the shaping hole 2 are detonated, the empty height of the chute is maintained at 8-11m.

[0022] After the blasting of the descending hole 1, shaping hole 2, main blasting hole 4, and buffer hole 3 is completed, the blast pile within 5m of the resulting horizontal chute opening 14 and its surrounding area must be cleared before the ore chute discharge operation can be carried out. In order to ensure that there is sufficient free surface during the blasting of descending hole 1 and shaping hole 2 and to prevent large rocks exceeding the standard from entering the chute, the chute clearance height should be maintained between 8 and 11m during the blasting. The ore chute discharge operation can only be carried out after the blast pile within 5m of the resulting horizontal chute opening 14 and its surrounding area has been cleared.

[0023] The beneficial effects of this invention are:

[0024] 1) The present invention designs the first ring of descending holes 1 and the second ring of shaping holes 2 around the wellhead as φ90 small-diameter inclined blast holes, which are evenly distributed in a fan shape on the upper and lower flat plates. Each hole adopts a radially uncoupled charging structure with a small charge amount, which greatly reduces the impact and damage to the surrounding rock of the wellhead when the explosive at the bottom of the blast hole detonates. This solves the problem of wellhead collapse caused by the excessive charge at the bottom of the hole when φ200 vertical blast holes are arranged around the wellhead in the original technology, which increases the fracture range of the surrounding rock of the wellhead.

[0025] 2) A third ring of buffer holes 3 is arranged between the shaping hole 2 and the main blast hole 4. The detonation time is delayed after the shaping hole 2 and the adjacent main blast hole 4. It is equivalent to a solid retaining wall with a preset width of about 4.5m. It can reduce the impact and damage of the stress wave of the main blast hole 4 on the chute wall 7. At the same time, the buffer hole 3 adopts a small amount of explosive and a segmented charging structure. After the blast, it can break this part of the solid retaining wall, avoiding the presence of residual foundation between the shaping hole 2 and the main blast hole 4. This solves the problem of the main blast hole 4 being too close to the chute wall in the original technology, which has a large impact and damage effect on the chute wall 7.

[0026] 3) The radial decoupled charge structure is adopted for the descending hole 1 and the shaping hole 2, the segmented charge structure is adopted for the other buffer holes 3 and the main blasting hole 4, and the micro-delay initiation technology is adopted for the descending hole 1, the shaping hole 2, the buffer hole 3 and the main blasting hole 4. This minimizes the blasting vibration hazard effect, ensures the integrity and stability of the surrounding rock of the chute wall 7, and solves the problem that the original technology only adopted the segmented charge structure for the first ring of descending holes 1 around the chute opening and the simultaneous detonation of the first ring of descending holes 1 around the chute opening caused a large vibration damage to the surrounding rock of the chute wall 7.

[0027] 4) The over-depth values ​​of the descending hole 1, the shaping hole 2, and the buffer hole 3 are 0.5m, 1m, and 1.5m, respectively. Compared with the over-depth value of the blast hole at the same position in the original technical solution, it is reduced by 0.5m. This not only helps to maintain the integrity of the surrounding rock at the bottom of the chute, but also forms a reverse slope of 2% to 5% around the bottom of the chute, so that the unloading platform at the chute is compliant with laws and regulations.

[0028] 5) The blasting of the ore pass adopts a hole layout of 1 descending hole, 2 shaping hole, 3 buffer hole and 4 main blasting hole. The gas spacing, radial decoupling and segmented charge structure and micro-delay initiation of each blast hole are used to make the explosive distribution at the bottom of the 1 descending hole, 2 shaping hole, 3 buffer hole and 4 main blasting hole more dispersed and minimized. This can minimize the vibration and impact damage during the blasting of the ore pass and its surrounding blast holes, and ensure the integrity and stability of the surrounding rock of the ore pass.

[0029] 6) By adopting the hole layout method of descending hole 1, shaping hole 2, buffer hole 3 and main blasting hole 4, the design and construction operation of descending blasting in the ore pass are standardized, refined and effective, which explores an effective way for descending blasting design of deep ore passes in open-pit mines and is conducive to the long-term stable operation of deep ore passes in open-pit mines.

[0030] 7) By adopting the hole layout method of descending hole 1, shaping hole 2, buffer hole 3, and main blasting hole 4 for descending blasting, the relative integrity of the ore pass can be ensured in essence. This effectively solves the problems of ore pass collapse and large slag enlargement and the difficulty of screen installation, and avoids large blocks entering the ore pass and causing blockage accidents. At the same time, it can reduce the consumption of explosives and increase the lump ore rate. It provides referable and scalable technical experience for descending blasting of deep ore passes in open-pit mines, and has good economic and social benefits.

[0031] 8) This invention standardizes and refines the design of blasting for descending sections in open-pit mines, and explores a new and effective blasting technology path for descending sections in deep open-pit mines. Compared with the original non-fixed descending section blasting scheme, it is more operable and has better blasting effect. Attached Figure Description

[0032] Figure 1 This is a plan view of the layout of blasting holes for the quarry descending section in this invention;

[0033] Figure 2 This is a cross-sectional view of the blasting hole arrangement for the ore pass in this invention.

[0034] Figure 3 This is a comparison diagram of the dimensions of the chute opening before and after the blasting of the No. 4 chute in this embodiment of the invention.

[0035] In the diagram: 1. Descending section hole, 101. Filling section I, 102. Charge section I, 2. Shaping hole, 201. Filling section II, 202. Buffer hole, 3. First filling section, 301. First charge section, 302. Second filling section, 303. Second charge section, 304. Gas compartment II, 305. Main blast hole, 4. Top line of upper flat plate, 5. Bottom line of lower flat plate, 6. Cutter wall, 7. Filling section, 8. Gas compartment, 9. Main charge, 10. Ultra-deep section, 11. Secondary charge, 12. Horizontal chute opening before descending blast, 13. Horizontal chute opening after descending blast, 14. Horizontal cross section of the horizontal chute before descending blast, 15. Detailed Implementation

[0036] The following will be combined with the appendix Figure 1-3 The present invention will be further described below.

[0037] To verify the effectiveness of this invention, on April 17, 2022, the design and practice of descending-stage blasting for No. 4 ore pass were carried out according to the hole layout method and hole-by-hole initiation network technology described in this invention. The No. 4 ore pass currently has an upper opening length of 25.1m, a width of 16.58m, a lower opening length of 10.09m, and a width of 7.74m, with a wall slope angle of 50.56° to 71.35°. The descending-stage height of the ore pass is 12m, presenting an "elliptical trumpet-shaped opening." A total of 122 blasting holes were designed, including 23 descending-stage holes 1, 23 shaping holes 2, 17 buffer holes 3, and 59 main blasting holes. The total charge was 17,520kg, consuming 198 digital electronic detonators. A hole-by-hole micro-delay initiation method was used. The measured empty height of the ore pass before initiation was 10.8m, and the measured blast volume after blasting was approximately 83,000 tons.

[0038] The present invention provides a blasting hole for descending sections in a deep open-pit mine ore pass, comprising a descending section hole 1, a shaping hole 2, a buffer hole 3, and a main blasting hole 4;

[0039] The descending hole 1 includes a plugging section I101 and a charge cartridge I102. The charge cartridge I102 is fixedly connected to the bottom surface of the plugging section I101. The charge capacity of a single hole is 55-60 kg. The function of the descending hole 1 is to lower the height of the horizontal chute 13 before the descending blast by one stage after detonation. The chute is lowered by 12 m, forming a new horizontal chute with a platform of 1-1.5 m in edge contour and width.

[0040] The shaping hole 2 includes a filling section II 201 and a charge cartridge II 202. The bottom surface of the filling section II 201 is fixedly connected to the charge cartridge II 202. The charge capacity of a single hole is 55-60 kg. The shaping hole 2 mainly serves to widen the working platform of the horizontal chute 14 after the descending blast. After detonation, it can form a stable platform 4-5 m wide around the horizontal chute 14 after the descending blast.

[0041] The buffer hole 3 includes a first filling section 301, a first drug roll section 302, a second filling section 303, a second drug roll section 304, and a gas spacer II 305. The bottom surface of the first filling section 301 is connected to the first drug roll section 302, the bottom surface of the first drug roll section 302 is connected to the second filling section 303, the bottom surface of the second filling section 303 is connected to the second drug roll section 304, and the bottom surface of the second drug roll section 304 is provided with a gas spacer II 305. The first drug roll section 302 and the second drug roll section 304 form a secondary drug column 12, with a single hole drug loading capacity of 115-120 kg.

[0042] The main blast hole 4 includes a plugging section 8, a gas spacer I 9, and a main explosive charge 10. The bottom surface of the plugging section 8 is provided with a gas spacer I 9, and the bottom surface of the gas spacer I 9 is connected to the main explosive charge 10. The charge per hole is 210-220 kg, and the explosive charge in one blast is 50,000-60,000 tons. After the blast pile is loaded, a transportation operation platform with a width of more than 15m can be formed around the horizontal chute opening 14 after the descending blast.

[0043] The diameter of the descending hole 1 is 90mm, the inclination angle α1 of the descending hole 1 is 60°~80°, the depth of the descending hole 1 is 12.5m, of which the over-depth is 0.5m, and there are 23 descending holes 1. The hole depth L1 is obtained according to the formula L1=H÷sinα1+C1. The number of holes is obtained by dividing the perimeter when the outline of the upper opening of the chute is expanded by 0.5m by the hole spacing. The first descending hole 1 is laid first and its direction is perpendicular to the upper and lower openings of the chute. Starting from the first descending hole 1, the hole positions of the remaining descending holes 1 are designed according to the method of equal division with a hole spacing of 3m from the top line 5 of the upper flat plate and a hole spacing of 1.93m from the bottom line 6 of the lower flat plate. The descending hole 1 adopts a radially uncoupled charging structure, with a charge diameter of 70mm, a filling height of 2~2.5m, and a single hole charge of 55kg.

[0044] The diameter of the shaped hole 2 is 90mm, the inclination angle α2 of the shaped hole 2 is 65°~85°, the depth of the shaped hole 2 is 13m, of which the extra depth is 1.0m, and the number of shaped holes 2 is 23; the row spacing b2 of the upper plate is 2m, the hole spacing a2 is 3.5m; the extra depth C2 is 1m, the hole depth L2 is obtained according to the formula L2=H÷sinα2+C2, and the number of holes is obtained by dividing the perimeter of the line connecting the holes 1 of the lower section of the upper plate by the hole spacing when it is expanded by 2m; the row spacing b of the lower plate is... 2d =2.5m; the hole spacing of the lower plate is determined by dividing the circumference of the lower plate when the line connecting the descending hole 1 to the lower plate is extended by 2.5m by the number of blast holes, and the a of the No. 4 ore pass. 2d = 2.66m; The first fixed hole 2 is laid out first with its orientation perpendicular to the upper and lower openings of the chute. Taking the first fixed hole 2 as the starting point, the positions of each fixed hole 2 are designed according to the method of equal division of the hole spacing on the upper plate (3.5m) and the hole spacing on the lower plate (2.66m); The inclination angle α2 of the fixed hole 2 is calculated according to ctgα2=(b2+H×ctgα1-b 2d The design tilt angle α2 is calculated using the formula α = 60.28 ÷ H. ° ~86.14 ° Between; the azimuth angle of each shaped hole 2, that is, the oblique angle or the included angle between two adjacent holes, is laid out at the drilling site according to the coordinate points of the bottom and the opening of the hole; the shaped hole 2 adopts a radially uncoupled charge structure, the charge roll diameter is 70mm, the filling height is 2~2.5, and the charge per hole is 55~60kg.

[0045] The buffer hole 3 has a diameter of 200mm, is a vertical blast hole, and has a blast hole depth of 13.5m, including an extra depth of 1.5m. There are 17 buffer holes 3 in total, and the blast holes are 90mm in diameter. ° Vertical holes; extra-deep 1.5m, hole depth L3=13.5m; the row spacing of the shaping hole 2 is 2m, the row spacing of the main blast hole 4 is 2.5m, and the hole spacing is 5m; the row spacing of the lower flat plate buffer hole 3 from the shaping hole 2 is designed to be 2.5~4m, therefore, the method of adding φ90mm inclined blast holes between the buffer holes 3 with a row spacing of more than 4m at the bottom of the hole is adopted; the buffer hole 3 adopts a gas interval plus segmented charging structure, the gas interval height at the bottom of the hole is 1m, the upper part of the gas interval is the main charge of 120kg and 4.4m high, the upper part of the main charge is filled with 2.5m and then a 30kg auxiliary charge is charged, the height of the filling section from the hole mouth to the auxiliary charge is about 4.4m.

[0046] The main blasting hole 4 has a diameter of 200mm and is a vertical blasting hole. There are 59 main blasting holes 4. The blasting parameters are as follows: the hole network parameters are 5m×7m, that is, the hole spacing of the front row is 6-6.5m, the hole spacing of the rear row is 6.5-7m, the row spacing is 5m, the row spacing with the buffer hole 3 is 1.5-2m, the blasting hole depth of the main blasting hole 4 is 14-14.5m, of which the extra depth is 2-2.5m; the main blasting hole 4 adopts a gas-interval charging structure with the explosive charge at the top. The explosive charge of the front row is 220kg, the explosive charge of the rear row is 210kg, the gas interval height is 1.5m, and the filling height is 5m.

[0047] A method for laying out blasting holes in a deep open-pit mine ore pass for descending sections includes the following steps:

[0048] 1) Along the horizontal chute opening 13 before the blasting of the descending section, descending section hole 1, shaping hole 2, buffer hole 3, and main blasting hole 4 are arranged outward in sequence;

[0049] 2) The descending section hole 1 is the first ring of blast holes arranged along the edge of the chute opening;

[0050] 3) The shaping hole 2 is the second ring of blast holes immediately adjacent to the descending section hole 1;

[0051] 4) The buffer hole 3 is the third ring of blast holes located between the shaping hole 2 and the main blast hole 4;

[0052] 5) The main blast hole 4 is the fourth ring of blast holes adjacent to the buffer hole 3.

[0053] A blasting method for blasting boreholes in the deep pass of an open-pit mine includes the following steps: The blasting of the pass's descending sections employs a detonation sequence of descending borehole 1, shaping borehole 2, main blasting borehole 4, and buffer borehole 3. Descending borehole 1 is detonated in two paths with slight delays, one descending borehole 1 is selected as the detonation point, and the slight delay times for adjacent descending boreholes 1 on both sides are 20ms and 30ms respectively. Other adjacent descending boreholes 1 are detonated with a slight delay of 20ms. The shaping borehole 2 that is detonated first has a delay time set to 65ms, and is detonated in two paths with slight delays, one on the left and one on the right. The delay times for the two shaping boreholes 2 adjacent to the first detonating borehole 2 are 85ms and 95ms respectively. Other adjacent shaping boreholes 2 are detonated with a slight delay of 20ms. The detonation time is ms; the main detonation holes 4 are detonated one by one in the order from the front row main detonation holes 4 to the back row main detonation holes 4. The delay time of the first detonating main detonation hole 4 is 130ms, the micro-difference time between adjacent main detonation holes 4 is 25ms, and the micro-difference time between rows is 65ms; the buffer hole 3 is detonated with a micro-difference time 25ms later than the adjacent main detonation hole 4.

[0054] When the descending hole 1 and the shaping hole 2 are detonated, the empty height of the chute is maintained at 8-11m.

[0055] After the blasting of the descending hole 1, shaping hole 2, main blasting hole 4, and buffer hole 3 is completed, the blast pile within 5m of the resulting horizontal chute opening 14 and its surrounding area must be cleared before the ore chute discharge operation can be carried out. In order to ensure that there is sufficient free surface during the blasting of descending hole 1 and shaping hole 2 and to prevent large rocks exceeding the standard from entering the chute, the chute clearance height should be maintained between 8 and 11m during the blasting. The ore chute discharge operation can only be carried out after the blast pile within 5m of the resulting horizontal chute opening 14 and its surrounding area has been cleared.

[0056] The aforementioned perforation parameters are row spacing × hole spacing.

[0057] After adopting the new hole layout method for blasting, the No. 4 ore pass in the lower section formed an ore pass opening (referred to as "lower opening") with a length of 11.49m and a width of 10.15m on the lower flat plate. This is significantly smaller than the original upper opening, which was 25.1m long and 16.58m wide. The lower opening of the ore pass meets the conditions for the installation of screens and steel retaining walls. The surrounding rock of the ore pass is relatively intact, and the unloading platform is stable. Moreover, with the reduction of explosive consumption per unit compared to the original scheme, the excavability of the blast pile has improved, and the ore block rate has increased. During the period from the completion of the blast pile loading and transportation out of the ore pass, no large blocks entered the ore pass and blocked the discharge port. This completely solved the problems existing in the original lowering section blasting technology, enabling the ore pass lowering section blasting technology to achieve a qualitative leap.

Claims

1. A blasting method for blasting boreholes in deep open-pit mine ore passes, characterized in that, Includes the following steps: The blasting of the ore pass adopts the following detonation sequence: descending hole (1), shaping hole (2), main blasting hole (4), and buffer hole (3). The descending hole (1) is detonated in two paths with micro-delay, one descending hole (1) is selected as the detonation point, and the micro-delay time of the two adjacent descending holes (1) is 20ms and 30ms respectively. Other adjacent descending holes (1) are detonated with a micro-delay time of 20ms. The first shaping hole (2) to be detonated has a delay time of 65ms and is detonated in two paths with micro-delay, one on the left and one on the right. The delay times of the two shaping holes (2) adjacent to the first detonating hole (2) are 85ms and 95ms respectively. Other adjacent shaping holes (2) are detonated with a micro-delay time of 20ms. The detonation time is ms; the main detonation holes (4) are detonated one by one in the order from the front row of main detonation holes (4) to the back row of main detonation holes (4), the delay time of the first detonating main detonation hole (4) is 130ms, the micro-difference time between adjacent main detonation holes (4) is 25ms, and the micro-difference time between rows is 65ms; the buffer hole (3) is detonated with a micro-difference time 25ms later than the adjacent main detonation hole (4); The blasting holes for descending sections in the deep pass of an open-pit mine include descending holes (1), shaping holes (2), buffer holes (3), and main blasting holes (4). The descending hole (1) includes a filling section I (101) and a drug roll section I (102). The bottom surface of the filling section I (101) is fixedly connected to the drug roll section I (102), and the single hole can hold 55-60 kg of drug. The shaped hole (2) includes a filling section II (201) and a medicine roll section II (202). The bottom surface of the filling section II (201) is fixedly connected to the medicine roll section II (202), and the medicine loading capacity of a single hole is 55-60 kg. The buffer hole (3) includes a first filling section (301), a first drug roll section (302), a second filling section (303), a second drug roll section (304), and a gas spacer II (305). The bottom surface of the first filling section (301) is connected to the first drug roll section (302), the bottom surface of the first drug roll section (302) is connected to the second filling section (303), the bottom surface of the second filling section (303) is connected to the second drug roll section (304), and the bottom surface of the second drug roll section (304) is provided with a gas spacer II (305). The first drug roll section (302) and the second drug roll section (304) form a secondary drug column (12), with a single hole loading capacity of 115-120 kg. The main blast hole (4) includes a plugging section (8), a gas spacer I (9), and a main explosive charge (10). The bottom surface of the plugging section (8) is provided with a gas spacer I (9), and the bottom surface of the gas spacer I (9) is connected to the main explosive charge (10). The charge per hole is 210-220 kg.

2. The blasting method for deep open-pit mine ore pass blasting holes as described in claim 1, characterized in that: When the descending hole (1) and the shaping hole (2) are detonated, the empty height of the chute is maintained at 8-11m.

3. The blasting method for deep open-pit mine ore pass blasting holes as described in claim 1, characterized in that: After the blasting of the descending section hole (1), shaping hole (2), main blasting hole (4), and buffer hole (3) is completed, the blast piles within a 5m radius of the horizontal chute opening (14) formed after the descending section blasting are cleared before the ore chute discharge operation is carried out.

4. The blasting method for deep open-pit mine ore pass blasting holes as described in claim 1, characterized in that: The diameter of the descending hole (1) is 90mm, the inclination angle α1 of the descending hole (1) is 60°~80°, the depth of the descending hole (1) is 12.5m, of which the extra depth is 0.5m, and the number of descending holes (1) is 21-23.

5. The blasting method for deep open-pit mine ore pass blasting holes as described in claim 1, characterized in that: The diameter of the shaped hole (2) is 90 mm, the inclination angle α2 of the shaped hole (2) is 65°~85°, the depth of the shaped hole (2) is 13 m, of which the extra depth is 1.0 m, and the number of shaped holes (2) is 21-23.

6. The blasting method for deep open-pit mine ore pass blasting holes as described in claim 1, characterized in that: The buffer hole (3) has a diameter of 200mm and is a vertical blast hole. The blast hole depth of the buffer hole (3) is 13.5m, of which the extra depth is 1.5m. The number of buffer holes (3) is 15-17.

7. The blasting method for descending blasting holes in a deep open-pit mine ore pass as described in claim 1, characterized in that: The main blast hole (4) has a diameter of 200mm and is a vertical blast hole. The blast hole depth of the main blast hole (4) is 14-14.5m, of which the extra depth is 2-2.5m. The number of main blast holes (4) is 57-59.

8. The blasting method for deep open-pit mine ore pass blasting boreholes as described in claim 1, characterized in that, The method for laying out blasting holes includes the following steps: 1) Along the horizontal chute opening (13) before the blasting of the descending section, descending section holes (1), shaping holes (2), buffer holes (3), and main blasting holes (4) are arranged outward in sequence; 2) The descending section hole (1) is the first ring of blast holes arranged along the edge of the chute opening; 3) The shaping hole (2) is the second ring of blast holes immediately adjacent to the descending section hole (1); 4) The buffer hole (3) is the third ring of blast holes located between the shaping hole (2) and the main blast hole (4); 5) The main blast hole (4) is the fourth ring of blast holes adjacent to the buffer hole (3).

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