Method and system for enhancing microwave fracturing

Abstract

The invention relates to a microwave cracking enhancing method and system. The microwave cracking enhancing method comprises the following steps that pyrite particles are prepared; polishing and cleaning the inner wall of the blast hole, and spraying a high-temperature-resistant adhesive on the cleaned inner wall of the blast hole; pyrite particles are evenly sprayed on the inner walls of the blast holes and compacted; and performing microwave fracturing on the blast hole by utilizing the heat effect of the microwave. The heat absorption efficiency of the blast hole surrounding rock is improved by injecting pyrite into the tunnel face blast hole, and the thermal damage process of the rock around the tunnel face blast hole is accelerated.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel engineering, and in particular to a method and system for enhancing microwave cracking. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Tunnel engineering often uses drilling and blasting method for drilling and blasting construction. For projects with lower grade surrounding rock, it can greatly speed up the tunnel excavation speed. However, for projects with higher grade and poorer quality surrounding rock, drilling and blasting method greatly increases the risk of rock burst.

[0004] Microwave fracturing technology can address the above problems and can be used to reduce the strength of the surrounding rock and reduce rock burst disasters. Microwaves are a type of electromagnetic radiation that can penetrate rocks and interact with the molecules and ions in them. When the microwave energy matches the vibration frequency of the molecules or ions in the rock, they absorb the microwave energy, thereby heating and fracturing. The microwave heating effect depends on whether the microwave energy matches the vibration frequency of the molecules or ions in the rock. If the molecules or ions in the surrounding rock do not match the microwave energy, the heating and fracturing effect of the surrounding rock will be greatly limited. The composition of the surrounding rock is complex. Even if there are molecules or ions with a high degree of matching in the surrounding rock, it is difficult to achieve rapid heating of the surrounding rock due to the randomness and discreteness of their distribution. Summary of the invention

[0005] In order to solve the technical problems existing in the above-mentioned background technology, the present invention provides a method and system for enhancing microwave cracking, which adopts a pyrite mineral particle coating as a microwave direct heating layer. Since the selected pyrite mineral is a sensitive mineral, it has an extremely high heating rate under microwave radiation.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A first aspect of the present invention provides a method for enhancing microwave cracking, comprising the following steps:

[0008] Preparation of pyrite mineral particles;

[0009] Grind and clean the inner wall of the blasting hole, and spray high temperature resistant adhesive on the cleaned inner wall of the blasting hole;

[0010] Spray the pyrite mineral particles evenly on the inner wall of the blast hole and compact them;

[0011] Microwave fracturing is performed on the blast holes using the thermal effect of microwaves.

[0012] Furthermore, the particle size of the pyrite mineral is in the range of 20-35 μm.

[0013] Furthermore, after the pyrite mineral particles are prepared, they are sealed and stored in a dry environment.

[0014] Further, the inner wall of the blast hole is polished and cleaned, including:

[0015] Based on the size of the blasting hole, a matching grinding head is selected to grind the inner wall of the blasting hole;

[0016] Clean the dust and debris on the inner wall surface of the blasting hole after grinding.

[0017] Furthermore, one in and one out in the grinding process is considered as one cycle, and the grinding process is not less than 20 cycles.

[0018] Furthermore, the preparation process of the high temperature resistant adhesive comprises the following steps:

[0019] According to the required ratio, prepare the corresponding quality and matching raw materials, mix them and stir them evenly;

[0020] According to the required viscosity, add matching solvent to dissolve and dilute the mixed solution;

[0021] The bubbles in the mixed solution are discharged to obtain a prepared high temperature resistant adhesive.

[0022] Furthermore, during the spraying of the pyrite particles, the spraying pressure is adjusted to match the diameter of the blasting hole and the distance from the nozzle to the adhesive coating on the inner wall surface of the blasting hole.

[0023] Furthermore, the pyrite particles on the inner wall of the blasting hole are compacted, specifically: the surface of the rod-shaped tool is coated with high-temperature resistant lubricating oil, and when the adhesive reaches 80%-90% of the fully solidified state, the rod-shaped tool is inserted into the blasting hole to hammer the inner wall of the blasting hole in all directions so that the thickness of the sprayed pyrite particles is within a set range.

[0024] Furthermore, the thickness of the sprayed pyrite particles is 1.0 mm to 1.5 mm, and the thickness error of the pyrite particles at various locations on the inner wall of the blasting hole is controlled within 0.5 mm.

[0025] A second aspect of the present invention provides a system for implementing the above method, comprising:

[0026] A grinding unit for producing pyrite ore particles;

[0027] Hole cleaning unit, used to grind and clean the inner wall of the blasting hole;

[0028] Spray gun, used to spray high temperature resistant adhesive on the inner wall of the cleaned blast hole;

[0029] Spraying machine, used to evenly spray pyrite mineral particles on the inner wall of the blast hole and compact them;

[0030] The microwave irradiation device uses the thermal effect of microwaves to perform microwave cracking on the blasting hole.

[0031] Compared with the prior art, one or more of the above technical solutions have the following beneficial effects:

[0032] 1. The pyrite particle coating is used as the microwave direct heating layer. The selected pyrite is a sensitive mineral, so it has an extremely high heating rate under microwave radiation.

[0033] 2. Microwave heating can cause temperature differences between the pyrite particle coating and the rock on the inner wall of the blasting hole, leading to thermal expansion and stress concentration. The thermal expansion and stress concentration effects can promote the expansion and rupture of microcracks in the rock and enhance the rock crushing and blasting effects.

[0034] 3. During microwave heating of the inner wall rock by introducing pyrite mineral particles, it is no longer restricted by the inherent components of the rock. The heated pyrite mineral particle coating can directly transfer heat to the rock around the inner wall through the heat conduction effect. Compared with direct microwave heating, the heat transferred by the pyrite mineral particle coating is more uniform, which reduces the rock strength to a certain extent, especially for the under-excavation working face that often occurs, and increases the blasting footage to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0036] Figure 1 A schematic diagram of a process for injecting pyrite particles into a blast hole according to one or more embodiments of the present invention;

[0037] Figure 2 A schematic diagram of the preparation process of a solvent-based high temperature resistant epoxy resin provided for one or more embodiments of the present invention. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0039] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0040] As introduced in the background technology, the composition of the surrounding rock is complex. Even if there are highly matching molecules or ions in the surrounding rock, it is difficult to achieve rapid heating of the surrounding rock due to the randomness and discreteness of their distribution, resulting in unsatisfactory microwave cracking effect.

[0041] Therefore, the following embodiment provides a method and system for enhancing microwave cracking, using a pyrite particle coating as a microwave direct heating layer. Since the selected pyrite is a sensitive mineral, it has an extremely high heating rate under microwave radiation.

[0042] Embodiment 1:

[0043] Figure 1 The schematic diagram of the process of injecting pyrite mineral particles into a blast hole in this embodiment is shown, which includes the following steps:

[0044] S1 crushes pyrite ore and uses a grinding machine to obtain pyrite mineral particles;

[0045] Specifically, pyrite is a mineral with high microwave absorption capacity. When exposed to microwave radiation, pyrite can absorb microwave energy and convert it into heat energy. This can generate heat on the inner wall of the blast hole and affect the surrounding rocks through heat conduction.

[0046] The particle size of pyrite is controlled within the range of 20-35μm, and its specific particle size is based on the suitability for the sprayer. After the pyrite particles of the specified particle size are prepared, they are ground twice to ensure that there are no protruding particle sizes. After grinding, they are sealed and stored in a dry environment.

[0047] S2 uses a ceramic grinding head to roughen the inner wall of the blasting hole and remove dust and debris from the inner wall of the blasting hole;

[0048] Specifically, a cylindrical ceramic grinding head is used to roughly grind the inner wall of the blasting hole. The diameter, height, aperture of the grinding head and the length of the grinding head handle should be selected to suit the size of the blasting hole. It is stipulated that the ceramic grinding head should be ground in one cycle, and the inner wall of the blasting hole should be ground for no less than 20 cycles to ensure that the entire inner wall of the hole can be ground. The inner wall of the blasting hole should be rough and uniform enough to increase the adhesion of the pyrite mineral particles.

[0049] After the rough grinding of the inner wall surface of the blasting hole is completed, the dust and debris on the inner wall surface of the blasting hole are discharged out of the blasting hole mainly by using a dust blowing gun, supplemented by a scraper and a wooden brush, so that the pyrite minerals and adhesives can adhere better.

[0050] S3 sprays high temperature resistant adhesive on the inner wall of the blasting hole;

[0051] Specifically, the high temperature resistant adhesive can form a heat resistant surface layer under high temperature conditions. The adhesive is a solvent-based high temperature resistant epoxy resin. The selection of the high temperature resistant curing agent and the high temperature resistant filler is subject to the manufacturer. The specific preparation ratio is based on the product manual. Figure 2 The schematic diagram of the preparation steps of solvent-based high temperature resistant epoxy resin is shown, and the preparation process includes the following steps:

[0052] S3.1 Prepare epoxy resin, curing agent and filler of corresponding quality and matching according to the provided ratio;

[0053] An epoxy resin with high temperature resistance is selected as the base material, a curing agent is used to react with the epoxy resin to achieve curing, and a high temperature resistant filler can improve the thermal stability and mechanical strength of the epoxy resin.

[0054] S3.2 Pour the epoxy resin, curing agent and filler into the mixing container in the provided ratio, stirring while mixing. The stirring time and method can be adjusted according to the specific epoxy resin product and the manufacturer's requirements. Ensure that the mixing is even until there is no obvious color stratification;

[0055] S3.3 According to the viscosity of the solvent-based high temperature resistant epoxy resin to be prepared, add an appropriate amount of acetone solvent into the mixing container, stir while adding, dissolve and dilute the epoxy resin mixed solution, so as to realize the spraying of the solvent-based high temperature resistant epoxy resin;

[0056] S3.4 Tap the mixing container housing to help expel air bubbles from the mixed solution.

[0057] The presence of bubbles can reduce the strength and durability of the material and cause structural defects in the final cured coating, such as holes, cracks or uneven surfaces. Removing bubbles can ensure that the cured epoxy resin mixture has the expected physical properties.

[0058] S4 After the adhesive is sprayed, the pyrite mineral particles are quickly and evenly sprayed on the inner wall of the blasting hole;

[0059] Specifically, a sprayer is used to spray pyrite particles, with the nozzle located at the center of the blasting hole aperture, and the spraying pressure is adjusted according to the specific aperture size and the distance from the nozzle to the adhesive coating on the inner wall surface to minimize the impact damage to the adhesive coating;

[0060] The spraying process is carried out slowly, and pyrite mineral particles are evenly spread on the inner wall of the blasting hole according to the set microwave irradiation range, without missing spraying or overspraying, and the formation of gaps is avoided as much as possible. The specified spraying thickness is 1.0mm-1.5mm, and the spraying thickness error at each location on the inner wall of the blasting hole is controlled within 0.5mm, and uneven heating of the inner wall of the blasting hole within the microwave irradiation range is avoided as much as possible.

[0061] The spraying angle of the sprayer depends on the position of the blasting hole. The spraying angle of the blasting holes at the edge of the face is 0°-180°, and the spraying angle of the internal blasting holes is 360°. The spraying thickness of the pyrite mineral particles decreases gradually from the blasting hole in the center of the face to the blasting hole at the edge.

[0062] S5 uses a pressure device to slightly compact the pyrite mineral particles and the inner wall of the blast hole;

[0063] Specifically, an iron rod, a rubber rod or a rod-shaped tool is used for slight compaction and consolidation. The compaction steps include:

[0064] S5.1 Take an iron rod or rubber rod of a length and diameter that meets the blast hole size;

[0065] The length should be greater than the depth of the blasting hole by 1m, and the diameter should be about 1cm smaller than the diameter of the blasting hole, so that the iron rod or rubber stick can be swung in all directions.

[0066] S5.2 Apply high temperature resistant lubricating oil on the iron rod or rubber rod to avoid the sprayed pyrite mineral particles being rubbed off or brought out of the blasting hole during compaction;

[0067] S5.3 According to the consolidation time provided by the manufacturer, when the adhesive reaches 80%-90% of complete consolidation, use a compaction tool to perform compaction operation;

[0068] When the adhesive reaches 80%-90% of the fully solidified state, the adhesive layer is not yet fully solidified and has a certain plasticity. This period is used to slightly compact and tighten the pyrite particles to ensure the continuous compactness of the pyrite particle coating and the uniformity of heating of the pyrite particle coating under microwave radiation.

[0069] S5.4 Insert an iron rod or rubber rod into the blasting hole and lightly hammer it in all directions, such as up, down, left, and right, so that the mineral particles sprayed on the inner wall of the blasting hole are lightly compacted and tightened;

[0070] If the spraying thickness after compaction and tightening is not within the specified thickness range, steps S3 to S5 are repeated.

[0071] S6 placing the microwave output end of the microwave irradiation device into the blasting hole for microwave heating;

[0072] Specifically, the microwave irradiation system includes a telescopic device and a rotating device. The telescopic device is used to adjust the extension length of the microwave output end, and the rotating device is used to adjust the rotation angle of the microwave output end. The irradiation power, irradiation time and irradiation area of ​​the microwave irradiation system are set according to actual needs. Excessive power and excessively long heating time may lead to excessive and uneven heating, and appropriate testing and debugging are required. During the heating process, tools such as thermometers are used to monitor the temperature changes of the rock to ensure that heating is carried out within a safe range and avoid exceeding the thermal stability and thermal tolerance of the rock.

[0073] The pyrite particle coating is used as the microwave direct heating layer. The selected pyrite is a sensitive mineral and has a very high heating rate under microwave radiation.

[0074] On the one hand, microwave heating can cause a temperature difference between the pyrite particle coating and the rock on the inner wall of the blast hole, resulting in thermal expansion and stress concentration. The thermal expansion and stress concentration effects can promote the expansion and rupture of microcracks in the rock, enhancing the rock crushing and blasting effect.

[0075] On the other hand, the method of heating the inner wall rock using pyrite is no longer limited by the inherent composition of the rock. The heated pyrite particle coating can directly transfer heat to the surrounding rock of the inner wall through the heat conduction effect. Compared with direct microwave heating, the heat transferred by the pyrite particle coating is more uniform, which reduces the rock strength to a certain extent, especially for the under-excavation working face that often occurs, and increases the blasting footage to a certain extent.

[0076] Embodiment 2:

[0077] A system for implementing the above method comprises:

[0078] A grinding unit for producing pyrite ore particles;

[0079] Hole cleaning unit, used to grind and clean the inner wall of the blasting hole;

[0080] Spray gun, used to spray high temperature resistant adhesive on the inner wall of the cleaned blast hole;

[0081] Spraying machine, used to evenly spray pyrite mineral particles on the inner wall of the blast hole and compact them;

[0082] The microwave irradiation device uses the thermal effect of microwaves to perform microwave cracking on the blasting hole.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for enhancing microwave cracking, characterized in that: The following steps are involved: Preparation of pyrite mineral particles; Grind and clean the inner wall of the blasting hole, and spray high temperature resistant adhesive on the cleaned inner wall of the blasting hole; Spray the pyrite mineral particles evenly on the inner wall of the blast hole and compact them; Microwave fracturing is performed on the blast holes using the thermal effect of microwaves.

2. A method for enhancing microwave cracking according to claim 1, characterized in that: The particle size of the pyrite mineral is in the range of 20-35 μm.

3. A method for enhancing microwave cracking according to claim 1, characterized in that: After the pyrite mineral particles are prepared, they are sealed and stored in a dry environment.

4. A method for enhancing microwave cracking according to claim 1, characterized in that: Grind and clean the inner wall of the blast hole, including: Based on the size of the blasting hole, a matching grinding head is selected to grind the inner wall of the blasting hole; Clean the dust and debris on the inner wall surface of the blasting hole after grinding.

5. A method for enhancing microwave cracking according to claim 4, characterized in that: In the grinding process, one in and one out is considered as one cycle, and the grinding process is not less than 20 cycles.

6. A method for enhancing microwave cracking according to claim 1, characterized in that: The preparation process of the high temperature resistant adhesive includes the following steps: According to the required ratio, prepare the corresponding quality and matching raw materials, mix them and stir them evenly; According to the required viscosity, add matching solvent to dissolve and dilute the mixed solution; The bubbles in the mixed solution are discharged to obtain a prepared high temperature resistant adhesive.

7. A method for enhancing microwave cracking according to claim 1, characterized in that: During the spraying of the pyrite particles, the spraying pressure is adjusted to match the diameter of the blasting hole and the distance from the nozzle to the adhesive coating on the inner wall surface of the blasting hole.

8. A method for enhancing microwave cracking according to claim 1, characterized in that: The pyrite particles on the inner wall of the blasting hole are compacted, specifically: the surface of the rod-shaped tool is coated with high temperature resistant lubricating oil, and when the adhesive reaches 80%-90% of the fully solidified state, the rod-shaped tool is inserted into the blasting hole to hammer the inner wall of the blasting hole in all directions, so that the thickness of the sprayed pyrite particles is within a set range.

9. A method for enhancing microwave cracking according to claim 8, characterized in that: The thickness of the sprayed pyrite particles is 1.0mm-1.5mm, and the thickness error of the pyrite particles at various locations on the inner wall of the blasting hole is controlled within 0.5mm.

10. A microwave cracking enhancement system, characterized in that: include ： A grinding unit for producing pyrite ore particles; Hole cleaning unit, used to grind and clean the inner wall of the blasting hole; Spray gun, used to spray high temperature resistant adhesive on the inner wall of the cleaned blast hole; Spraying machine, used to evenly spray pyrite mineral particles on the inner wall of the blast hole and compact them; The microwave irradiation device uses the thermal effect of microwaves to perform microwave cracking on the blasting hole.

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