A microwave-fracture agent in-situ fracturing device and method for drilling and mining ore

Abstract

The present invention aims to provide a microwave-expansion agent in-situ fracturing device and method for drilling and mining ore. This device, which belongs to the field of drilling and mining technology, utilizes rectangular and circular waveguides in conjunction with a coaxial core to achieve focused radiation, generating directional initial cracks within the borehole at a predetermined angle. Static fracturing agents are then injected into the initial cracks in sections and at varying pressures. Utilizing the crack expansion effect brought about by the expansion pressure, in-situ secondary fracturing is performed within the microwave fracturing range to promote secondary crack expansion. By superimposing the fracturing ranges of microwaves and fracturing agents, a large-area interconnected fracture network dominated by microwave-directed fractures is formed. Ultimately, while ensuring the fracturing range and effectiveness, the device reduces drilling holes, increases the spacing between boreholes, and improves mining efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling mining, and in particular relates to a microwave-fracture agent in-situ fracturing device and method for drilling mining of ore. Background Art

[0002] As one of the mining methods for hard mineral rocks, the drilling mining method is widely used in the fields of metal mines, stone, etc. This method usually involves excavating holes at predetermined locations in the area to be mined, and using some high-efficiency rock-breaking technologies such as blasting, carbon dioxide, and hydraulic fracturing to destroy the rock strata on the hole wall, so that a network of cracks is formed between multiple boreholes to weaken the strength of the rock strata and peel off the mineral rocks. Currently, blasting and hydraulic fracturing are more commonly used methods. They have more efficient rock-breaking or directional capabilities and are applicable to different engineering conditions. However, they also bring about varying degrees of safety and pollution issues, such as blasting vibrations may cause rock bursts, and hydraulic fracturing drainage may pollute the working environment.

[0003] Microwaves, an emerging rock-breaking technology, offer unique selective heating properties that enable silent, vibration-free, and pollution-free rock fragmentation, holding great promise for application, particularly in drilling and mining. However, despite their penetrating heating capabilities, microwave transmission within rock formations is affected by dielectric properties, resulting in a gradual attenuation process. This significantly limits the range of microwave fracturing. Therefore, under certain conditions, combined rock-breaking methods—fracturing followed by secondary fracturing—can effectively address this issue. Many researchers have also proposed using rock-breaking technologies such as carbon dioxide guns, supercritical carbon dioxide, water, dry ice, liquid nitrogen, and ultrasound to enhance fracturing effectiveness. However, due to differences in rock-breaking mechanisms, these methods and microwave-based rock-breaking methods often face drawbacks and inconsistencies when combined. For example, impact-vibration fracturing methods like carbon dioxide guns and ultrasound are buffered by microwave cracks, reducing both efficiency and effectiveness. Temperature-shock methods like water, dry ice, and liquid nitrogen, however, lack control over the direction and location of the fractures. At the same time, these microwave-assisted rock-breaking methods focus on weakening the rock formation, ignoring the impact of the fracturing range on efficient mining. This results in the secondary fracturing range still starting at the borehole wall. In reality, even a lower weakening of the borehole wall after two fracturing cycles can still meet mining requirements. Therefore, a rational microwave-assisted rock-breaking device and method is urgently needed that can effectively expand the combined fracturing range while maintaining the fracturing effect, achieving in-situ directional fracturing, reducing the number of drilling holes, and improving drilling efficiency.

[0004] The patent number is CN202010768522.1, "Microwave-assisted pressure relief and support method for deep hard rock engineering". This method pre-drills a hole in the face, introduces microwaves into the hole to achieve primary fracturing of the surrounding rock formations, and then injects an expansion crushing agent to achieve secondary fracturing. Although this rock breaking method can effectively achieve secondary development of cracks, it still has the following shortcomings. First, the microwave heating method of this method is full-borehole heating, and the selective heating characteristics of microwaves make the cracks develop randomly within its radiation surface, and a directional effect cannot be achieved. The uncontrollable range and direction of fracturing result in large energy consumption and a relatively small damage range; second, the slurry injection method is direct injection, which is only effective for bottom plate drilling. For top plate drilling, the high temperature state of the hole wall rock layer after microwave heating will accelerate the hydration reaction rate. If the hole is deep, the slurry will first accumulate at the hole mouth and react quickly. The grouting port is blocked, and the rock formation at the bottom of the hole is not expanded and broken, resulting in uneven fracturing of the borehole, poor fracturing effect, and the inability to guarantee the fracturing range; thirdly, this method requires microwaves and grouting equipment to be pushed in and out cyclically to complete radiation and grouting, which is inefficient and requires more steps; fourthly, the transmission of microwaves in the borehole uses the hole wall as a transmission and reflection channel, which is inefficient and has large losses. The energy received by the radiation area is uneven, resulting in uneven crack development and secondary fracturing effect after the injection of the crushing agent; fifthly, the radiation object of this method is the bottom of the borehole, and the crack network is only formed at the bottom, and fracturing in the shallow part of the borehole cannot be achieved.

[0005] Patent number CN202110818807.6, "Device and method for shale gas extraction using microwave irradiation combined with dry ice fracturing," and patent number CN202210814840.6, "Method for constructing an artificial heat reservoir in hot dry rock using microwave radiation and dry ice jets," are available. Both rock-breaking methods use microwaves to preheat the wellbore wall before injecting dry ice to achieve thermal shock fracture. While this combined rock-breaking method can effectively increase the degree of rock destruction, it still has the following shortcomings. First, low-temperature impact cracks mainly develop on both sides of the main cracks, and have no obvious beneficial effect on the expansion of the main cracks and the increase of the fracturing range; second, dry ice, as a cooling method, achieves fracturing through heat conduction, and only impacts the surface, with low destructive effect and limited impact range; third, after low-temperature impact, dry ice cannot effectively support the generated cracks, which may cause the cracks to close under the action of surrounding rock stress; fourth, the cracks generated by this microwave radiation method and low-temperature impact process are relatively random, and the fracturing direction and fracturing range are not controllable; fifth, during deep well operations, there is no protective device on the outside of the pipeline, and it is very likely that the hole will collapse, resulting in pipeline interruption and the abandonment of the drilling.

[0006] Patent number CN202410969226.6 is titled "A Combined Microwave and Carbon Dioxide Blasting Method for Deep Metal Ore Breaking." This method employs multiple annular bags positioned outside a sleeve to secure it. Microwave radiation then heats the borehole wall in sections. Once heated, liquid carbon dioxide is rapidly injected, utilizing the high temperature to induce a phase change and generate cracks. This method has the following shortcomings. First, it uses carbon dioxide blasting as a secondary fracturing method, primarily through gas shock waves. However, after microwaves generate cracks, a buffer layer forms within the crack space, reducing the fracturing effect. Second, the phase change rate of carbon dioxide in this method is determined by the borehole wall temperature, while liquid carbon dioxide injection is accompanied by a cooling effect, making the timing of the phase change reaction uncertain. Furthermore, deep boreholes suffer from uneven destruction, resulting in poor overall controllability. Third, in this combined fracturing method, carbon dioxide blasting has a higher fracturing effect and range than microwaves, resulting in a smaller fracturing range primarily determined by the amount of carbon dioxide used. Furthermore, there is little correlation or interaction between the two methods in terms of fracturing. Fourthly, the annular bag of this method is in direct contact with the high-temperature hole wall rock layer, resulting in a high damage rate. Microwaves are penetrating heating, and when radiated in a confined space, they will reflect and heat the water in the bag. The high temperature and steam generated will also cause damage to the bag. Fifthly, this method requires repeated removal and insertion of the microwave device and the carbon dioxide injection device during segmentation. If deep hole operations are used, the workload is large and the efficiency is low.

[0007] The patent number is CN202310697352.6, "A continuous mining device for crushing hard rock and its application method". This method uses supercritical carbon dioxide to form tiny cracks, then microwaves accelerate the reaction to weaken the rock formation, and finally achieves mining through a cutting system. This method has the following main shortcomings. First, the fracturing method in this method is mainly supercritical carbon dioxide, and microwaves are only catalytic reaction devices. The degree of crack development of supercritical carbon dioxide is proportional to its contact area with the rock formation. When the rock formation is dense or hard rock with few primary cracks, the reduction in contact area will significantly reduce the fracturing efficiency, resulting in poor applicability. Second, supercritical carbon dioxide is a non-polar molecule with extremely low dielectric loss and relatively poor dielectric properties, while microwave catalysis mainly targets polar molecular systems. Therefore, supercritical carbon dioxide has a weak ability to absorb microwaves, and the catalytic method may be less effective, resulting in low overall fracturing efficiency. Third, this fracturing method is extremely dependent on porosity and the development of primary cracks, so it is impossible to control the range and direction of fracturing, and it is easy to cause large differences in the fracturing effect in different areas of the hole. Fourth, the supercritical carbon dioxide injection device and the microwave radiation device are both extended into the borehole for operation. This method does not consider the damage of supercritical carbon dioxide to the microwave device during injection and its prevention and control methods.

[0008] The patent number is CN202310318166.7, "A method for mining by microwave heating and water cooling to induce fracture and collapse". This method is to irradiate microwaves in the borehole, fracture and heat the rock formation, then inject water for low-temperature impact, and finally achieve drilling mining through natural collapse method. This method has the following shortcomings. First, the secondary fracturing medium of this method is water, which can only develop cracks through low temperature, resulting in poor fracturing effect, and the cracks may close under the stress of the surrounding rock after formation; second, this method also only uses temperature shock for fracturing, and the controllability of the fracturing range and direction is poor, and the fracturing uniformity of the hole wall rock layer is also poor; third, this method requires continuous pushing and pulling of the device to achieve cyclic fracturing of microwaves and water in the same borehole. While the operation intensity is high, the fracturing efficiency is also low, and the defects are particularly obvious when the drilling depth is large; fourth, in this method, the hole walls around the microwave radiation port are all radiation surfaces, and the hole wall rock layer is uneven. When used as a transmission reflection channel, the energy received by the radiation area is uneven, the efficiency is low, and a directional effect cannot be achieved. The fracturing range and direction are not controllable. Summary of the Invention

[0009] The present invention addresses the problem that when microwaves are used for drilling and mining hard mineral rocks, due to transmission loss and power limitation, the cracks generated by microwaves are not only relatively small in range but also have poor connectivity with each other. Therefore, a microwave-fracture agent in-situ fracturing device and method for drilling and mining mineral rocks are provided.

[0010] The present invention utilizes microwave heating to create temperature gradients between minerals to create initial fractures. Static fracturing agent slurry is then injected into the fractures to achieve in-situ secondary fracturing. This not only extends the fracture length and increases the damage range, but also promotes interconnection of fractures through expansion pressure, forming a large-scale interconnected fracture network. Furthermore, the device transmits microwaves via rectangular waveguides combined with segmented circular waveguides, significantly reducing energy loss within the hole and ensuring uniform radiation across each section of the hole wall. Furthermore, by grading the discharge pressure, the slurry is injected in stages, from deep to shallow, promoting consistent loading of the rock formation. This device offers the advantages of directional fracturing and controllable position.

[0011] The present invention adopts the following technical solutions:

[0012] A microwave-fracture agent in-situ fracturing device for drilling and mining ore, comprising a microwave system, a liquid injection system and a sleeve system;

[0013] The microwave unit includes a microwave power source and a three-end circulator. The output end of the microwave power source is connected to the input end of the three-end circulator. The right-angle output end of the three-end circulator is connected to a water load, and the other output end is connected to a three-pin adapter. The output end of the three-pin adapter is sequentially connected to a right-angle bend waveguide and a rectangular waveguide. The rectangular waveguide extends into a drilled hole. A plurality of circular waveguides are provided on the rectangular waveguide. The circular waveguides are symmetrically arranged on both sides of the rectangular waveguide along the length direction and are arranged at equal intervals.

[0014] Furthermore, the liquid injection system includes a mixing barrel and a grouting pump, a water inlet pipe is provided at the top of one side of the mixing barrel, a stirring motor is provided at the top of the mixing barrel, a stirring impeller is connected to the output end of the stirring motor, the bottom end of one side of the mixing barrel is connected to the grouting pump through a slurry suction pipe, a slurry outlet pipe is provided on one side of the grouting pump, a pressure gauge and a motor are provided at the top of the grouting pump, and an air compressor is provided on one side of the grouting pump.

[0015] Furthermore, the sleeve system includes a shell located in the drilled hole, a rectangular waveguide located in the shell, a vibrator is provided at the top of the shell, and a plurality of anti-return sealing devices are provided on the outside of the shell. The anti-return sealing devices are arranged alternately with the circular waveguide, and a plurality of slurry outlets are provided on the side wall of the shell.

[0016] Furthermore, a coaxial core is provided at the center of the circular waveguide in the axial direction, and a wave-transmitting plate is provided at the output port of the circular waveguide.

[0017] Furthermore, the anti-return sealing device is located at the center of two adjacent circular waveguides. The anti-return sealing device is an umbrella-shaped hollow ring structure. The diameter of the outer ring of the hollow ring is 20 mm smaller than the diameter of the drilled hole. The outer surface of the anti-return sealing device is wrapped with a basalt fiber cloth layer, and a pneumatic telescopic screw is provided at the bottom of the anti-return sealing device.

[0018] Furthermore, a pressure-adjustable safety valve is provided at the slurry outlet, and the opening pressure of the safety valve decreases from the shallow part to the deep part of the borehole.

[0019] Furthermore, the slurry outlet pipe of the grouting pump is connected to the slurry outlet of the shell through a diverter valve, and the air compressor is connected to the pneumatic telescopic screw and the vibrator through an air inlet pipe.

[0020] A method for drilling and mining ore, comprising the following steps:

[0021] S1. Determine microwave radiation parameters based on the geological conditions of the ore deposit and the planned drilling plan. Drill holes are drilled in advance. The drilling holes are arranged in a rectangular pattern with equal spacing between rows. After cleaning the silt from the holes, mark the circular waveguide radiation direction at the hole mouth. Use two radiation angles, 45° and 135°, arranged in an oblique orthogonal staggered pattern. This ensures that the radiation angle of this drill hole is different from that of the four drill holes above, below, and to the left and right, to maximize the coverage of the fracture.

[0022] S2. Adjust the pneumatic telescopic screw of the check hole sealing device to the appropriate position according to the borehole diameter, ensuring that the outer side of the check hole sealing device is in close contact with the hole wall when placed in the borehole;

[0023] S3. Connect the rectangular waveguide, circular waveguide, and various pipes into the housing in sequence. Lead the pipes out of the opening through the interlayer between the rectangular waveguide and the housing and connect them to corresponding positions respectively.

[0024] S4. Push the shell into the drill hole, rotate the output port of the circular waveguide to the predetermined fracturing direction and position according to the hole radiation direction mark, and support and fix it with a backstop sealing device;

[0025] S5. Turn on the microwave power source and preheat for 30 seconds before starting to output microwaves. The incident wave passes through the rectangular waveguide and the circular waveguide in conjunction with the coaxial inner core to continuously and directionally focus the stratum on the hole wall according to the predetermined time.

[0026] S6. Turn on the mixing impeller, pour water and static cracking agent into the mixing bucket according to the water-cement mass ratio of 1:3 and mix well. At the same time, adjust the pressure of the grouting pump for standby use;

[0027] S7. After the microwave radiation is completed within the predetermined time, the temperature of the rock formation on the borehole wall increases significantly, and initial cracks are formed in the radiation direction. At this time, the slurry outlet pipe is immediately opened, and the slurry enters the pipeline in the hole through the diverter valve. The pipeline pressure increases rapidly, and the safety valve of the first slurry outlet in the deep part of the borehole opens. The slurry begins to be injected into the initial cracks in the first section of the borehole wall, and the pipeline pressure drops. At this time, the slurry temperature is relatively low, causing the first temperature shock to the deep rock formation, which promotes the further development of the cracks.

[0028] S8, after the first section of the hole wall rock formation absorbs the slurry to saturation, the pipeline pressure is increased again until the safety valve of the second section of the liquid outlet is opened, and the slurry is injected into the second section of the initial fracture to further fracture the hole wall rock formation;

[0029] S9. Repeat steps S7 and S8 until the pore wall rock absorbs the slurry until it is saturated. At this point, the high temperature of the rock layer accelerates the hydration reaction of the fracturing agent. The initial cracks develop mainly in the form of expansion under the action of expansion pressure. The crack length, the number of connected cracks, and the fracturing range all increase significantly, eventually forming a large-scale interconnected crack network with radial cracks as the main fracture direction.

[0030] S10. After fracturing is completed, due to the increase in the volume of the cracks, the space in the hole is expanded accordingly, and the powder product after the reaction of the fracturing agent will be loose. At this time, turn on the air compressor, run the vibrator and retract the pneumatic telescopic screw, use vibration to compact the powder, realize the separation of the shell and the hole wall, and slowly take out the shell.

[0031] The beneficial effects of the present invention are as follows:

[0032] 1. This invention uses microwave radiation to generate initial fractures, achieving a directional effect. Static fracturing agents are then injected to achieve in-situ secondary fracturing. Microwave-generated fractures are numerous but lack connectivity. Static fracturing agents, on the other hand, primarily develop fractures through tensile failure, extending in the direction of the weak plane. Therefore, when combined with the slurry, the expansion pressure from the slurry entering the initial microwave-generated fractures significantly increases fracture aperture and length, interconnecting numerous fractures and forming a large-scale fracture network, increasing the range and severity of damage within a single well. Furthermore, the secondary fracturing targets the rock formation at the fracture tips, meaning that secondary fractures begin to expand within the microwave-generated fracture range (initial fractures). This allows for a combined fracturing range to be calculated. In contrast, the secondary fracturing in other combined rock-breaking methods targets the borehole surface, resulting in a fracturing range that is only the maximum of one method, without achieving the desired combined effect. Furthermore, the initial fractures formed are likely to act as a buffer layer, significantly reducing the effective damage range of shock wave fracturing methods.

[0033] 2. The microwave and static fracturing agents described in this invention both achieve low or no vibration during the fracturing process. Combined fracturing also achieves low-vibration fracturing, eliminating impact and vibration while also eliminating noise and dust pollution. Furthermore, during the combined fracturing process, the rock formation within the borehole wall is subjected to a cyclical temperature shock cycle of high temperature (microwave radiation), low temperature (slurry immersion), and high temperature (hydration reaction), resulting in a high degree of borehole wall damage, enabling efficient and environmentally friendly mining.

[0034] 3. The rock-breaking device of the present invention uses a rectangular waveguide for microwave transmission within the borehole and a circular waveguide for output. All transmission channels utilize standard waveguide components, resulting in much higher transmission efficiency than output ports located at the borehole entrance. Through reflection from the borehole wall, microwave energy is evenly distributed throughout the borehole, avoiding the problem of inconsistent radiation intensity at rock formations at different depths.

[0035] 4. During the fracturing process of this combined rock breaking method, the forces acting on each section of the rock formation and the final degree of fracturing can be kept basically consistent, achieving the effect of controllable fracturing range. In addition, the rock breaking device can achieve two in-situ fracturing operations in one operation.

[0036] 5. The static fracturing agent is injected in stages, first deep and then shallow, to prevent premature clogging of the shallow outlet due to the high temperature of the borehole rock. The static fracturing agent forms a solid powder after reaction, which effectively supports the fracture and prevents it from closing.

[0037] 6. The segmented circular waveguide is equipped with a coaxial inner core, which has the function of guiding microwaves to focus radiation at one point. The single point energy density is high, and the connection between two or more output ports is conducive to directional fracturing.

[0038] 7. The use of an oblique orthogonal staggered method to arrange drill holes, combined with the fracture network formed by the directional fracturing device, can maximize the coverage of the gaps between drill holes, thereby ensuring the fracturing effect while increasing the spacing between drill holes, effectively improving the drilling and fracturing efficiency and saving drilling costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural diagram of the device of the present invention;

[0040] Figure 2 This is a schematic diagram of the installation of the device of the present invention in a borehole;

[0041] Figure 3 for Figure 1 AA sectional view;

[0042] Figure 4 for Figure 1 BB cross-sectional view;

[0043] Figure 5 The schematic diagram of microwave radiation directions of each borehole arranged according to the oblique orthogonal staggered method;

[0044] Among them: 1- microwave power source; 2- three-end circulator; 3- water load; 4- three-pin dispenser; 5- right-angle bend waveguide; 6- rectangular waveguide; 7- circular waveguide; 8- coaxial inner core; 9- wave-transparent plate; 10- mixing barrel; 11- water inlet pipe; 12- mixing motor; 13- mixing impeller; 14- slurry suction pipe; 15- grouting pump; 16- slurry outlet pipe; 17- diverter valve; 18- pressure gauge; 19- motor; 20- air compressor; 21- air inlet pipe; 22- housing; 23- vibrator; 24- check and sealing device; 25- slurry outlet; 26- pneumatic telescopic screw; 27- safety valve; 28- drilling hole; 29- rock to be mined. DETAILED DESCRIPTION

[0045] The present invention will be further described with reference to the accompanying drawings.

[0046] As shown in the figure, a microwave-fracture agent in-situ fracturing device for drilling and mining ore includes a microwave system, a liquid injection system and a sleeve system;

[0047] The microwave unit includes a microwave power source 1 and a three-end circulator 2. The output end of the microwave power source 1 is connected to the input end of the three-end circulator 2. The right-angle output end of the three-end circulator 2 is connected to a water load 3, and the other output end is connected to a three-pin adapter 4. The output end of the three-pin adapter 4 is sequentially connected to a right-angle bend waveguide 5 and a rectangular waveguide 6. The rectangular waveguide 6 extends into a borehole 28. A plurality of circular waveguides 7 are provided on the rectangular waveguide 6. The circular waveguides 7 are symmetrically arranged on both sides of the rectangular waveguide 6 along the length direction and are arranged at equal intervals.

[0048] The sleeve system includes a shell 22 located in the drilled hole 28, the rectangular waveguide 6 is located in the shell 22, a vibrator 23 is provided at the top of the shell, and a plurality of anti-return sealing devices 24 are provided on the outside of the shell 22. The anti-return sealing devices 24 are arranged alternately with the circular waveguide 7, and a plurality of slurry outlets 25 are provided on the side wall of the shell 22.

[0049] The output microwave frequency of the microwave power source 1 is 2450 MHz, and the maximum power is 15 kW continuously adjustable; the three-terminal circulator 2, water load 3, three-pin adapter 4, right-angle bend waveguide 5, and rectangular waveguide 6 are all WR340 standard waveguide components, made of aluminum, with flange connection. The dimensions of the rectangular waveguide 6 are 86.36 mm long and 43.18 mm wide.

[0050] The liquid injection system includes a mixing barrel 10 and a grouting pump 15. A water inlet pipe 11 is provided at the top of one side of the mixing barrel 10, a stirring motor 12 is provided at the top of the mixing barrel 10, and a stirring impeller 13 is connected to the output end of the stirring motor 12. The bottom end of one side of the mixing barrel 10 is connected to the grouting pump 15 through a slurry suction pipe 14, a slurry discharge pipe 16 is provided on one side of the grouting pump 15, a pressure gauge 18 and a motor 19 are provided at the top of the grouting pump 15, and an air compressor 20 is provided on one side of the grouting pump 15.

[0051] The circular waveguide 7 is provided with a coaxial inner core 8 in the center along the axial direction, which is made of an electrical conductor material. The output port of the circular waveguide 7 is provided with a wave-transparent plate 9 for sealing and waterproofing. The plate is made of a phosphate-based composite wave-transparent material with a wave transmittance of not less than 80%.

[0052] The anti-return sealing device 24 is located at the center of two adjacent circular waveguides 7. It is an umbrella-shaped hollow ring structure. The outer ring diameter is 20 mm smaller than the diameter of the drilled hole 28. It is welded to the housing 22 via its inner ring. Its frame is made of carbon steel. The outer surface of the anti-return sealing device 24 is wrapped with a basalt fiber cloth layer, with a thickness that is close to the drilled hole wall (no less than 10 mm). A pneumatic telescopic screw 26 is installed at the bottom of the anti-return sealing device 24 to ensure support and sealing. The basalt fiber cloth is a flexible material with high strength, water-proofing, and high-temperature resistance (no less than 700°C).

[0053] The slurry outlet 25 is provided with a pressure-adjustable safety valve 27. The opening pressure of the safety valve 27 decreases from the shallow part to the deep part of the borehole 28 to ensure that the opening pressure of the deep safety valve is lower than that of the shallow part. The slurry is preferentially injected into the deeper section to prevent the shallow slurry from reacting quickly and clogging the pipeline.

[0054] The slurry outlet pipe 16 of the grouting pump 15 is connected to the slurry outlet 25 of the housing 22 through a diverter valve 17, and the air compressor 20 is connected to the pneumatic telescopic screw 26 and the vibrator 23 through an air inlet pipe 21.

[0055] A method for drilling and mining ore, comprising the following steps:

[0056] S1. Determine microwave radiation parameters based on the geological conditions of the ore deposit and the planned drilling plan. Drill holes are drilled in advance. The drilling holes are arranged in a rectangular pattern with the same spacing between rows. After cleaning the silt in the holes, mark the circular waveguide radiation direction at the hole mouth. Use two radiation angles, 45° and 135°, in an oblique orthogonal staggered arrangement. Use the diagonal line of the rectangle as the reference line, and set the angles alternately in every other row. The circular waveguides are arranged in an "X" shape. This ensures that the radiation angle of any drill hole is different from that of the four drill holes above, below, and to the left and right of it, but the angle is the same as that of the diagonal oblique drill hole, thereby maximizing the coverage area of ​​the fracture.

[0057] S2. Adjust the pneumatic telescopic screw 26 of the check and sealing device 24 to a suitable position according to the borehole diameter, ensuring that the outer side of the check and sealing device 24 is in close contact with the hole wall when placed in the borehole 28;

[0058] S3. Connect the rectangular waveguide 6, circular waveguide 7 and each pipe to the housing 22 in sequence. The pipes are led out from the opening through the interlayer between the rectangular waveguide 6 and the housing 22 and connected to corresponding positions respectively.

[0059] S4. Push the housing into the borehole 28, rotate the output port of the circular waveguide 7 to the predetermined fracturing direction and position according to the borehole radiation direction mark, and support and fix it with the backstop sealing device 24;

[0060] S5. Turn on the microwave power source 1 and preheat for 30 seconds before starting to output microwaves. The incident wave passes through the rectangular waveguide 6 and the circular waveguide 7 in conjunction with the coaxial inner core 8 to continuously and directionally focus the stratum on the hole wall according to the predetermined time.

[0061] S6. Turn on the mixing impeller 13, pour water and static fracturing agent into the mixing barrel 10 in a water-cement mass ratio of 1:3 and mix well, while adjusting the pressure of the grouting pump 15 for standby use; the static fracturing agent is an inorganic compound mainly composed of calcium oxide, which is mixed with water to form a slurry, which expands in volume through a hydration reaction and then squeezes and crushes the rock.

[0062] S7. After the microwave radiation is completed within the predetermined time, the temperature of the rock formation on the borehole wall increases significantly, and initial cracks are formed in the radiation direction. At this time, the slurry outlet pipe 16 is immediately opened, and the slurry enters the pipeline in the hole through the diverter valve 17. The pipeline pressure increases rapidly, and the safety valve 27 of the first slurry outlet deep in the borehole opens. The slurry begins to be injected into the initial cracks in the first section of the borehole wall, and the pipeline pressure drops. At this time, the slurry temperature is relatively low, causing the first temperature shock to the deep rock formation, which promotes the further development of the cracks.

[0063] S8, after the first section of the hole wall rock formation absorbs the slurry to saturation, the pipeline pressure is increased again until the safety valve of the second section of the liquid outlet is opened, and the slurry is injected into the second section of the initial fracture to further fracture the hole wall rock formation;

[0064] S9, repeating steps S7-S8 until the pore wall rock layer absorbs the slurry to a saturated state. At this time, the high temperature of the rock layer accelerates the hydration reaction of the fracturing agent. The initial cracks develop mainly in the form of expansion under the action of expansion pressure. The crack length, the number of connected cracks, and the fracturing range all increase significantly, eventually forming a large-area connected crack network with radial cracks as the main fractures.

[0065] S10. After the fracturing is completed, the crack volume increases and the space in the hole expands accordingly. The powder product after the reaction of the fracturing agent will be loosened. At this time, the air compressor 20 is turned on, the vibrator 23 is operated, and the pneumatic telescopic screw 26 is retracted. The powder is compacted by vibration to achieve the separation of the shell from the hole wall, and the shell is slowly taken out.

[0066] Example

[0067] An iron ore mine uses a horizontal, layered open-pit mining method. The deposit consists of banded quartz-type hematite. This ore is dense and strong, with a maximum compressive strength of 203.9 MPa. Geological data indicates that the mineral composition of quartz-type hematite primarily includes hematite, quartz, and wüstite.

[0068] (1) Based on the geological data of the mine, the size of the test ore body to be drilled was determined to be 4m×7m, with a single mining depth of 10m. Large rock samples were taken from the ore deposit for preliminary experiments. After irradiation with a microwave power of 15kW for 3 minutes, macroscopic cracks appeared in the rock samples. After the fracturing agent was injected at this time, the reaction time was about 70 minutes, and the single hole crushing range was about 780mm.

[0069] (2) Based on the preliminary experimental results, the microwave-fracture agent combined fracturing scheme is comprehensively determined as follows: the spacing between the boreholes is 1.5m, with 5 boreholes in each row, 3 rows arranged, a total of 15 boreholes, 15 sets of sleeve system shells are made, the borehole depth is 10m, and it is drilled vertically on the surface of the ore deposit. The microwave power is 15kW, the radiation time is 3min, and the slurry is injected immediately after the radiation. The segment length is 1m, with a total of 10 segments, 2 circular waveguides in each segment, with a spacing of 1m, a total of 20, and a total of 10 slurry outlets. The pressure of the first slurry outlet (the deepest section of the borehole) is set to 0.5MPa, and each section increases by 0.5MPa. The pressure of the tenth section (the shallowest section of the borehole) is 5MPa. The borehole diameter is 135mm, the outer diameter of the sleeve is 90mm, the total diameter after the check sealing device is supported is 114mm, and the thickness of the basalt fiber cloth wrapping is 22mm;

[0070] (2) Install all sleeve systems into the borehole, check the sealing performance, ensure that the check-hole sealing device is close to the hole wall, and rotate the sleeve to the predetermined fracturing position;

[0071] (3) First, connect the water pipe, slurry suction pipe, liquid injection pipe, air intake pipe, and waveguide components to the predetermined position of borehole No. 1 for standby use;

[0072] (4) Open the mixing barrel, add water and static cracking agent in proportion, stir well and set aside. The impeller should be stirred continuously to prevent sinking;

[0073] (5) After preheating the microwave power source, start the microwave radiation and set the radiation time to 3 minutes;

[0074] (6) Grouting begins immediately after the radiation is completed. The slurry first enters the first section with a lower opening pressure, and gradually enters the tiny cracks generated by microwave radiation. After saturation, the pressure rises, the second section valve opens, and grouting begins to circulate to the tenth section. At this time, the borehole is subjected to the low-temperature impact of the slurry, and the cracks will further develop. It is necessary to ensure that the grouting pump pressure is not lower than 5MPa. When the pressure is maintained at a high state for a certain period of time, the crack development stops, indicating that the borehole has reached saturation, and grouting is stopped;

[0075] (7) Remove the pipes and waveguide components outside the hole and connect them to borehole No. 2. Repeat steps 4 to 6 to fracture all boreholes in sequence;

[0076] (8) About 2 hours after the grouting is completed, the borehole experiences temperature shock and expansion and extrusion, forming a large-area fracture network with the segmented circular waveguide radiation direction as the main fracture. The boreholes are interconnected, realizing the in-situ combined fracturing of the mining area by microwave-fracture agent, which greatly reduces the ore strength without pollution.

[0077] (9) The formation of cracks increases the volume of the drilled hole, and the powder is subsequently compacted by a vibrator and the sleeve system is removed.

Claims

1. A microwave-fracture agent in-situ fracturing device for drilling and mining ore, characterized by: Including microwave system, liquid injection system and sleeve system; The microwave system comprises a microwave power source (1) and a three-end circulator (2), the output end of the microwave power source (1) is connected to the input end of the three-end circulator (2), the right-angle output end of the three-end circulator (2) is connected to a water load (3), and the other output end is connected to a three-pin adapter (4), the output end of the three-pin adapter (4) is sequentially connected to a right-angle bend waveguide (5) and a rectangular waveguide (6), the rectangular waveguide (6) extends into a borehole (28), and a plurality of circular waveguides (7) are provided on the rectangular waveguide (6), and the circular waveguides (7) are symmetrically arranged on both sides of the rectangular waveguide (6) along the length direction and are arranged at equal intervals; The sleeve system includes a housing (22) located in a drill hole (28), a rectangular waveguide (6) located in the housing (22), a vibrator (23) provided at the top of the housing, a plurality of anti-return sealing devices (24) provided on the outside of the housing (22), the anti-return sealing devices (24) and the circular waveguide (7) being arranged alternately, and a plurality of slurry outlets (25) provided on the side wall of the housing (22); The anti-return sealing device (24) is located at the center of two adjacent circular waveguides (7). The anti-return sealing device (24) is an umbrella-shaped hollow circular ring structure. The diameter of the outer ring of the hollow circular ring structure is 20 mm smaller than the diameter of the drill hole (28). The outer surface of the anti-return sealing device (24) is wrapped with a basalt fiber cloth layer. The bottom of the anti-return sealing device (24) is provided with a pneumatic telescopic screw (26).

2. The microwave-fracture agent in-situ fracturing device for drilling and mining ore according to claim 1, characterized in that: The liquid injection system comprises a mixing barrel (10) and a grouting pump (15); a water inlet pipe (11) is provided at the top end of one side of the mixing barrel (10); a stirring motor (12) is provided at the top end of the mixing barrel (10); an output end of the stirring motor (12) is connected to a stirring impeller (13); a bottom end of one side of the mixing barrel (10) is connected to the grouting pump (15) via a grouting suction pipe (14); a grouting outlet pipe (16) is provided at one side of the grouting pump (15); a pressure gauge (18) and a motor (19) are provided at the top end of the grouting pump (15); and an air compressor (20) is provided at one side of the grouting pump (15).

3. The microwave-fracture agent in-situ fracturing device for drilling and mining ore according to claim 2, characterized in that: The circular waveguide (7) is provided with a coaxial inner core (8) at the center along the axial direction, and a wave-transmitting plate (9) is provided at the output port of the circular waveguide (7).

4. The microwave-fracture agent in-situ fracturing device for drilling and mining ore according to claim 3, characterized in that: The slurry outlet (25) is provided with a pressure-adjustable safety valve (27), and the opening pressure of the safety valve (27) decreases from the shallow part to the deep part of the borehole (28); The slurry outlet pipe (16) of the grouting pump (15) is respectively connected to the slurry outlet (25) of the housing (22) through a diverter valve (17), and the air compressor (20) is respectively connected to the pneumatic telescopic screw (26) and the vibrator (23) through an air inlet pipe (21).

5. A method for drilling and mining ore using the microwave-fracture agent in-situ fracturing device according to claim 4, characterized in that: The steps include: S1. Determine microwave radiation parameters based on the geological conditions of the ore deposit and the planned drilling plan. Drill holes are drilled in advance. The drilling holes are arranged in a rectangular pattern with equal spacing between rows. After cleaning the silt from the holes, mark the circular waveguide radiation direction at the hole mouth. Use two radiation angles, 45° and 135°, arranged in an oblique orthogonal staggered pattern. This ensures that the radiation angle of this drill hole is different from that of the four drill holes above, below, and to the left and right, to maximize the coverage of the fracture. S2. Adjust the pneumatic telescopic screw (26) of the check hole sealing device (24) to a suitable position according to the borehole diameter, ensuring that the outer side of the check hole sealing device (24) is in close contact with the hole wall when placed in the borehole (28); S3, connecting the rectangular waveguide (6), the circular waveguide (7) and each pipeline to the housing (22) in sequence, and leading the pipeline out from the opening through the interlayer between the rectangular waveguide (6) and the housing (22) and connecting to corresponding positions respectively; S4, pushing the housing into the borehole (28), rotating the output port of the circular waveguide (7) to a predetermined fracturing direction and position according to the borehole radiation direction mark, and supporting and fixing it with a backstop sealing device (24); S5, turning on the microwave power source (1) and preheating for 30 seconds before starting to output microwaves, the incident wave passes through the rectangular waveguide (6) and the circular waveguide (7) in conjunction with the coaxial inner core (8) to continuously and directionally focus the stratum on the hole wall according to a predetermined time; S6. Turn on the mixing impeller (13), pour water and static cracking agent into the mixing barrel (10) in a water-cement mass ratio of 1:3 and mix well, and adjust the pressure of the grouting pump (15) for standby use; S7. After the microwave radiation is completed at the predetermined time, the temperature of the rock formation on the hole wall increases significantly, and initial cracks are formed in the radiation direction. At this time, the slurry outlet pipe (16) is immediately opened, and the slurry enters the pipeline in the hole through the diverter valve (17). The pipeline pressure increases rapidly, and the safety valve (27) of the first slurry outlet in the deep part of the borehole is opened. The slurry begins to be injected into the initial cracks in the first section of the hole wall, and the pipeline pressure drops. At this time, the slurry temperature is relatively low, causing the first temperature shock to the deep rock formation, thereby promoting the further development of the cracks. S8, after the first section of the hole wall rock formation absorbs the slurry to saturation, the pipeline pressure is increased again until the safety valve of the second section of the liquid outlet is opened, and the slurry is injected into the second section of the initial fracture to further fracture the hole wall rock formation; S9, repeating steps S7-S8 until the pore wall rock layer absorbs the slurry to a saturated state. At this time, the high temperature of the rock layer accelerates the hydration reaction of the fracturing agent. The initial cracks develop mainly in the form of expansion under the action of expansion pressure. The crack length, the number of connected cracks, and the fracturing range all increase significantly, eventually forming a large-area connected crack network with radial cracks as the main fractures. S10. After the fracturing is completed, the crack volume increases and the space in the hole expands accordingly. The powder product after the reaction of the fracturing agent will be loosened. At this time, the air compressor (20) is turned on, the vibrator (23) is operated, and the pneumatic telescopic screw (26) is retracted. The powder is compacted by vibration to achieve the separation of the shell from the hole wall, and the shell is slowly taken out.

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