Microwave fracturing assisted blasting rock breaking method for hole wall of fan-shaped medium-length hole

Abstract

The invention relates to a fan-shaped medium-length hole wall microwave fracturing assisted blasting rock breaking method which comprises the following steps: S1, drilling in a stope according to a blasting design construction scheme; s2, generating a blast hole wall image before microwave radiation cracking; s3, microwave radiation fracturing is conducted on the blast hole, so that the wall of the blast hole and an ore body around the blast hole are fractured, and generation of microcracks in the ore body is promoted; s4, a blast hole wall image after microwave radiation is generated again, the microwave radiation cracking damage effect is analyzed, and when the effect is not ideal, microwave radiation cracking is conducted on the blast hole again; s5, the blast hole subjected to microwave radiation is washed; and S6, according to the blasting design scheme, the fan-shaped medium-length hole is subjected to explosive charging and filling and then detonating. According to the method, the microwave cracking technology and traditional explosive blasting are combined, the mechanical strength of the rock mass is reduced through the microwave cracking technology, then explosive blasting is conducted, and therefore the purposes of reducing explosive unit consumption, improving the blasting effect and improving the blasting efficiency are achieved.

Description

Technical Field

[0001] This invention relates to the field of engineering blasting technology, and in particular to a method for breaking rock by microwave-assisted fracturing of the borehole wall in a fan-shaped medium-deep hole. Background Technology

[0002] Due to its wide applicability, low excavation cost, simplicity, and high efficiency, the drill-and-blast method remains the main construction method for rock excavation.

[0003] With shallow surface resources nearly exhausted, deep-ground resource extraction has become an inevitable trend. As extraction depth increases, the stress environment becomes more complex, leading to difficulties in blasting during deep ore body mining, resulting in problems such as high explosive consumption, uneven blast block size distribution, and low blasting efficiency.

[0004] Microwave rock breaking, as an emerging rock breaking method, can effectively solve the above problems. Its basic principle is to rapidly raise the temperature of the rock through microwaves, thereby causing the rock to be destroyed under the combined effects of water evaporation, internal decomposition, and expansion. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a method for microwave-assisted blasting of rock breaking in a fan-shaped medium-deep hole. By combining microwave fracturing technology with traditional explosive blasting, the mechanical strength of the rock mass is reduced using microwave fracturing technology before explosive blasting, thereby reducing explosive consumption, improving blasting effect, and increasing blasting efficiency.

[0006] The technical solution adopted in this invention is as follows: The present invention proposes a method for microwave-assisted blasting and rock breaking in a fan-shaped medium-deep hole, which includes the following steps: S1. Drill holes in the mining area according to the blasting design and construction plan; after drilling is completed, clean the rock fragments in the holes and inspect the medium-deep holes according to the drawings. S2. Perform drilling photography on medium-deep holes to generate images of the borehole wall before microwave radiation-induced fracturing. S3. Using a microwave fracturing system, different microwave action parameters are set to induce microwave radiation fracturing in the borehole, causing fractures in the borehole wall and surrounding ore body, and promoting the generation of micro-fractures in the ore body. S4. Drill and photograph the medium-deep hole again to generate an image of the borehole wall after microwave radiation. Analyze the damage effect of microwave radiation cracking. If the effect is not ideal, microwave radiation cracking is performed on the borehole again. S5. Clean the boreholes after microwave irradiation to remove rock cuttings and other impurities. S6. According to the blasting design plan, charge and fill the deep holes in the fan shape before detonation.

[0007] Furthermore, in step S1, a hydraulic rock drilling rig is used for drilling.

[0008] Furthermore, in both steps S2 and S4, a multi-functional intelligent drilling television tester is used to perform drilling video recording.

[0009] Furthermore, in step S3, the microwave fracturing system includes a microwave generator, a microwave coaxial radiating tube, and a waveguide; the microwave coaxial radiating tube is installed at the output end of the microwave generator through the waveguide; the angle of the microwave generator is adjusted by a lifting platform and a universal ball joint to allow the microwave coaxial radiating tube and the waveguide to smoothly extend into the borehole; after the first point of microwave radiation in the borehole is completed, a waveguide is removed to proceed to the next point of microwave fracturing; after the last point of microwave radiation is completed, the microwave coaxial radiating tube is removed, and so on, until microwave radiation fracturing of the entire borehole is completed.

[0010] Furthermore, in step S3, a preliminary experiment is first conducted with a microwave power of 3kW; then the microwave power is increased, with the maximum microwave power not exceeding 15kW, and the microwave working time is set to induce microwave cracking of the hole wall in the deep hole of the fan shape.

[0011] Furthermore, in step S3, the range of microwave radiation-induced cracking is 18-22 cm.

[0012] Furthermore, in step S6, the explosive type is granular emulsified ammonium nitrate explosive, the loading method is full-section loading, and the loading is carried out using a loading device; the orifice blocking lengths are 1m, 4m and 7m respectively.

[0013] Furthermore, an electronic detonator initiation system is used for detonation, and the initiation method is reverse initiation.

[0014] Compared with the prior art, the present invention has the following advantages: This invention proposes a method for breaking rock by microwave fracturing assisted blasting of a fan-shaped medium-deep hole wall. By using microwave fracturing technology to reduce the mechanical strength of the rock mass, followed by explosive blasting, it can effectively reduce explosive consumption, improve blasting effect, and increase blasting efficiency. Attached Figure Description

[0015] Figure 1 This is a schematic diagram illustrating the process of implementing the present invention; Figure 2 A schematic diagram of the fan-shaped medium-deep borehole layout in a deep mining area of ​​an iron mine; Figure 3 A cross-sectional view of the rock mass surrounding the muzzle of a deep-hole fracturing device in a fan-shaped region; Figure 4 This is a cross-sectional view of the borehole after microwave-induced fracturing, captured by a borehole camera inside the borehole. Figure 5 This is a schematic diagram of the structure for loading explosives into a borehole after microwave-induced fracturing.

[0016] The attached figures are labeled as follows: 1-ore body, 2-blast hole, 3-microwave ceramic head, 4-microwave coaxial radiator tube, 5-polytetrafluoroethylene ring, 6-waveguide and coaxial radiator connecting screw, 7-waveguide, 8-microwave generator, 9-universal ball head, 10-slide rail, 11-lifting machine, 12-planar probe, 13-centerer, 14-push rod connector, 15-push rod, 16-connecting wire, 17-explosive, 18-filling. Detailed Implementation

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] See appendix Figure 1 The present invention proposes a method for microwave-assisted blasting and rock breaking in a fan-shaped medium-deep hole, which specifically includes the following steps: S1. According to the blasting design and construction plan, drill holes in the mining area using a hydraulic rock drilling rig; after drilling is completed, clean the rock fragments in the hole and inspect the medium-deep holes according to the drawings.

[0019] S2. Use a multi-functional intelligent borehole television tester to perform borehole photography on medium-deep holes and generate images of the borehole wall before microwave radiation-induced fracturing. The multifunctional intelligent borehole television tester includes a planar probe, connecting cable, wire release crank, tablet computer, push rod, and push rod connector.

[0020] S3. Using a microwave fracturing system, different microwave action parameters are set to induce microwave radiation fracturing in the borehole, causing fractures in the borehole wall and surrounding ore body, promoting the generation of micro-fractures in the ore body, expanding and reducing the mechanical strength of the ore body. The microwave fracturing system includes a microwave generator, a microwave coaxial radiating tube, and a waveguide; the microwave coaxial radiating tube is connected to the output end of the microwave generator through the waveguide; the number of microwave coaxial radiating tubes can be adjusted according to the depth of the medium-deep hole.

[0021] The bottom of the microwave generator is equipped with a lifting platform. The microwave generator is connected to the top of the lifting platform via a ball joint. The angle of the microwave generator can be easily adjusted using the lifting platform and the ball joint, so that the microwave coaxial radiation tube and waveguide can be smoothly inserted into the borehole. After the first point of microwave radiation in the borehole is completed, a waveguide is removed to proceed to the next point of microwave fracturing. After the last point of microwave radiation is completed, the microwave coaxial radiation tube is removed, and so on, until the microwave radiation fracturing of the entire borehole is completed. During the microwave radiation fracturing process, the microwave absorption capacity of the ore and rock was fully considered to avoid damage to the magnetron by microwave return waves. A preliminary experiment was conducted with a microwave power of 3kW. Then, the microwave power was increased, with the maximum microwave power not exceeding 15kW. The microwave working time was set, and microwave fracturing of the hole wall was carried out on the fan-shaped medium-deep hole. The range of microwave radiation fracturing inside the hole was about 18-22cm.

[0022] S4. Use the multi-functional intelligent borehole television tester again to perform borehole imaging on the medium-deep holes that have been cracked by microwave radiation, generate images of the borehole wall after microwave radiation, analyze the damage effect of microwave radiation cracking, and if the effect is not ideal, perform microwave radiation cracking on the borehole again. The multifunctional intelligent drilling television tester is an existing conventional device, which includes a planar probe, connecting cable, tablet computer, crank handle, push rod, push rod connector, centerer and cable take-up and release controller; S5. Clean the boreholes after microwave irradiation to remove rock cuttings and other impurities. S6. According to the blasting design plan, charge and fill the deep holes in the fan shape before detonation; The explosive type is granular emulsified ammonium nitrate explosive, and the charging method is full-section charging using a charging device. The orifice plugging lengths are 1m, 4m, and 7m respectively. An electronic detonator initiation system is used for detonation, and the initiation method is reverse initiation.

[0023] The present invention will be further illustrated below through specific embodiments and comparative examples: Example 1 A method for breaking rock by microwave-assisted blasting with fracturing of the borehole wall in a fan-shaped medium-deep hole, taking an iron mine as an example, is implemented as follows: S1: According to the design and construction plan for medium-deep hole blasting, use a hydraulic rock drilling rig to drill holes in the mining area; after drilling is completed, clean the rock fragments in the hole and inspect the medium-deep hole according to the drawings. The blasting design scheme is as follows: Figure 2 As shown; the blasting design and construction plan includes borehole length, angle, borehole spacing, row spacing, etc.

[0024] The acceptance criteria for medium-deep holes, based on the construction design drawings, include a hole depth error not exceeding ±0.5m, a borehole inclination angle error not exceeding ±0.1°, a borehole azimuth angle and forward tilt angle deviation not exceeding ±0.1°, and a medium-deep hole pass rate of over 85%.

[0025] S2: Taking hole 12 as an example (hole diameter 76mm, hole length 10.3m), a multi-functional intelligent borehole television tester is used to perform drilling video on the medium-deep hole and generate an image of the borehole wall before microwave radiation-induced cracking.

[0026] The multifunctional intelligent borehole television tester consists of a planar probe, connecting cable, tablet computer, crank handle, push rod, push rod connector, centerer, and cable take-up and release controller.

[0027] The process of generating the borehole wall image before microwave-induced fracturing includes the following steps: (1) cleaning the rock fragments inside the borehole. (2) connecting the probe, push rod connector, push rod, and wire take-up and release controller, installing the probe centerer, and connecting the tablet computer. (3) placing the probe in the fan-shaped deep borehole, and using the push rod to slowly and evenly push the probe into the borehole to make the image clear.

[0028] S3: Insert the microwave coaxial radiator into the borehole, adjust the angle of the microwave generator using a homemade lifting mechanism and a universal ball joint, and connect the microwave generator and the waveguide using external hex screws.

[0029] The cross-sectional view of the microwave coaxial radiator tube inserted into the borehole 12 is shown below. Figure 4 As shown. Each section of the microwave coaxial radiating tube is approximately 80cm long. The sections of the microwave coaxial radiating tube are connected by threads, and polytetrafluoroethylene gaskets are used at the joints to secure them and prevent arcing during the microwave radiation cracking process.

[0030] In this embodiment, based on the length of the borehole 12, 12 sections of microwave coaxial radiating tubes are used, and the microwave coaxial radiating tubes are connected to the microwave generator via waveguides. The range of microwave radiation fracturing within the borehole is approximately 20 cm; therefore, three 20 cm long waveguides are custom-made. After the first point of microwave radiation within the borehole is completed, one waveguide is removed to proceed to the next point of microwave fracturing. After the third point of microwave radiation is completed, one section of the microwave coaxial radiating tube is removed, and so on, until microwave radiation fracturing of the entire borehole is completed.

[0031] S4: Using a microwave fracturing system, different microwave action parameters are set to induce microwave radiation fracturing in the borehole, causing fractures in the borehole wall and surrounding ore body, promoting the generation and expansion of micro-fractures in the ore body, and reducing the strength of the ore body.

[0032] Set the microwave operating parameters, including filament current, magnetic field current, microwave power, start-up time, and operating time.

[0033] Before microwave fracturing began, the filament was preheated for 300 seconds using a current of 47A. After preheating, the magnetic field current was set to 3.6A for microwave fracturing, with a start-up time of 23 seconds. Considering the microwave absorption capacity of the ore and to avoid damage to the magnetron from microwave return waves, a preliminary experiment was conducted using a microwave power of 3kW. Then, the microwave power was increased, with a maximum microwave power not exceeding 15kW, and the microwave operating time was set to 300 seconds for microwave fracturing of the borehole walls in a sector-shaped medium-deep borehole.

[0034] S5: The multifunctional intelligent borehole television tester is used again to perform drilling and imaging on the medium-deep borehole irradiated with microwave radiation, generating images of the borehole wall after microwave radiation. The effect of microwave radiation-induced cracking damage is analyzed. If the effect is not ideal, microwave radiation cracking is performed on the borehole again.

[0035] By analyzing the images, we can identify the locations where microwave radiation cracking is not effective. By adjusting the number of sections in the microwave coaxial radiation tube, we can modify the length of the radiation tube and thus achieve secondary cracking at these locations.

[0036] Taking the secondary fracturing required at 1.5m inside the borehole as an example, two microwave coaxial radiating tubes need to be connected to perform fracturing at 1.6m. Then, a 20cm section of waveguide is removed from the microwave generator, and fracturing is performed again at 1.4m.

[0037] S6: Clean the boreholes after microwave irradiation to remove rock debris and other impurities.

[0038] S7: According to the charge structure of the blasting design, charge and fill the deep holes in the fan shape, and use an electronic detonator initiation system for detonation.

[0039] Explosive design charge structure such as Figure 5 As shown, the deep holes in the fan shape are loaded and plugged; the explosive type is granular emulsified ammonium nitrate explosive, and the BQF-100 type explosive can is used for loading. The entire section is loaded with explosive without setting an air gap. The detonation method is reverse detonation. The plugging lengths of the orifice are 1m, 4m and 7m respectively.

[0040] All matters not covered in this invention are common knowledge.

[0041] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for breaking rock using microwave-assisted blasting with fracturing of the borehole wall in a fan-shaped medium-deep hole, characterized in that, The method includes the following steps: S1. Drill holes in the mining area according to the blasting design and construction plan; after drilling is completed, clean the rock fragments in the holes and inspect the medium-deep holes according to the drawings. S2. Perform drilling photography on medium-deep holes to generate images of the borehole wall before microwave radiation-induced fracturing. S3. Using a microwave fracturing system, different microwave action parameters are set to induce microwave radiation fracturing in the borehole, causing fractures in the borehole wall and surrounding ore body, and promoting the generation of micro-fractures in the ore body. S4. Drill and photograph the medium-deep hole again to generate an image of the borehole wall after microwave radiation. Analyze the damage effect of microwave radiation cracking. If the effect is not ideal, microwave radiation cracking is performed on the borehole again. S5. Clean the boreholes after microwave irradiation to remove rock cuttings and other impurities. S6. According to the blasting design plan, charge and fill the deep holes in the fan shape before detonation.

2. The method for breaking rock by microwave-assisted blasting with fracturing of the borehole wall in a fan-shaped medium-deep hole according to claim 1, characterized in that: In step S1, a hydraulic rock drilling rig is used for drilling.

3. The method for breaking rock by microwave-assisted fracturing of the borehole wall in a fan-shaped medium-deep hole according to claim 1, characterized in that: In both steps S2 and S4, a multi-functional intelligent drilling television tester is used to perform drilling video recording.

4. The method for breaking rock by microwave-assisted blasting with fracturing of the borehole wall in a fan-shaped medium-deep hole according to claim 1, characterized in that: In step S3, the microwave fracturing system includes a microwave generator, a microwave coaxial radiating tube, and a waveguide. The microwave coaxial radiating tube is installed at the output end of the microwave generator via the waveguide. The angle of the microwave generator is adjusted by a lift and a universal ball joint to allow the microwave coaxial radiating tube and the waveguide to smoothly extend into the borehole. After the first point of microwave radiation in the borehole is completed, a waveguide is removed to proceed to the next point of microwave fracturing. After the last point of microwave radiation is completed, the microwave coaxial radiating tube is removed, and so on, until microwave radiation fracturing of the entire borehole is completed.

5. The method for breaking rock by microwave-assisted blasting with fracturing of the borehole wall in a fan-shaped medium-deep hole according to claim 1, characterized in that: In step S3, a preliminary experiment is first conducted with a microwave power of 3kW; then the microwave power is increased, with the maximum microwave power not exceeding 15kW, and the microwave working time is set to induce microwave cracking of the hole wall in the deep hole of the sector.

6. The method for breaking rock by microwave-assisted fracturing of the borehole wall in a fan-shaped medium-deep hole according to claim 4, characterized in that: In step S3, the range of microwave radiation-induced cracking is 18-22 cm.

7. The method for breaking rock by microwave-assisted blasting with fracturing of the borehole wall in a fan-shaped medium-deep hole according to claim 1, characterized in that: In step S6, the explosive type is granular emulsified ammonium nitrate explosive, the loading method is full-section loading, and the loading is carried out using a loading device; the orifice blocking lengths are 1m, 4m and 7m respectively.

8. The method for breaking rock by microwave-assisted fracturing of the borehole wall in a fan-shaped medium-deep hole according to claim 7, characterized in that: The detonation is initiated using an electronic detonator system, and the detonation method is reverse detonation.

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