Microwave-spalling agent in-situ fracturing device and method for drilling mining rock

Abstract

The invention aims at providing a microwave-spalling agent in-situ fracturing device and method for mining rock through drilling, and belongs to the technical field of drilling mining. A rectangular waveguide and a circular waveguide are matched with a coaxial inner core to achieve focused radiation, directional initial fractures are generated in a drilled hole according to a preset angle, and the directional initial fractures are fractured; and then a static spalling agent is injected into the initial fracture in a segmented and partial pressure mode, in-situ secondary fracturing is conducted on the basis of the microwave fracturing range by means of the fracture expansion effect brought by expansion pressure, and secondary expansion of the fracture is promoted. And by superposing the fracturing ranges of the microwaves and the spalling agent, a large-area communicated fracture network mainly comprising microwave directional fractures is formed. Finally, on the premise that the fracturing range and effect are guaranteed, the purposes of reducing mining drill holes, increasing the distance between the drill holes and improving the mining efficiency are achieved.

Description

Technical Field

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

[0002] As one of the mining methods for hard ore and rock, the drilling mining method is widely used in fields such as metal mines and stone materials. This method usually excavates drill holes at predetermined positions in the area to be mined, and cooperates with some efficient rock-breaking technologies such as blasting, carbon dioxide, and hydraulic fracturing to damage the rock layer on the hole wall, so as to form a fracture network between multiple drill holes to weaken the strength of the rock layer and achieve the purpose of exfoliating ore and rock. At present, the more commonly used methods are blasting and hydraulic fracturing, which have relatively high rock-breaking ability or directional ability and have a certain degree of applicability to different engineering conditions. However, the same brings safety and pollution problems to varying degrees. For example, blasting vibration may trigger rock bursts, and hydraulic fracturing drainage pollutes the working environment.

[0003] As a new rock-breaking technology, microwave can achieve the purpose of rock fragmentation silently, vibrationlessly and pollution-free with its unique selective heating characteristics, especially having good application prospects in the field of drilling mining. However, although microwave has the characteristics of penetrating heating, the transmission of microwave in the rock layer is affected by the dielectric properties and is still a gradually decaying process, which leads to a large limitation of the microwave fracturing range by the rock layer. Therefore, under some special conditions, a combined rock-breaking method can be adopted, and secondary fracturing after microwave fracturing can effectively solve this problem. Many scholars have also proposed to use rock-breaking technologies such as carbon dioxide guns, supercritical carbon dioxide, water, dry ice, liquid nitrogen, and ultrasonic waves to improve the fracturing effect. However, due to the differences in rock-breaking mechanisms, there are certain drawbacks and irrationalities in the combined rock-breaking methods of the above methods and microwave. For example, the impact vibration fracturing methods such as carbon dioxide guns and ultrasonic waves will be buffered by the microwave fractures, resulting in reduced efficiency and effect, while the temperature impact types such as water, dry ice, and liquid nitrogen are uncontrollable in terms of fracturing direction and initiation position. At the same time, the focus of these microwave combined rock-breaking methods is on the weakening amplitude of the rock layer strength, ignoring the impact of the fracturing range on efficient mining, so that the starting point of the secondary fracturing range is still the drill hole wall. In fact, in the case of the rock layer on the hole wall being subjected to two fracturings, even a relatively low weakening amplitude can meet the mining requirements. Therefore, there is an urgent need for a reasonable microwave combined rock-breaking device and method, which can effectively increase the combined fracturing range on the basis of ensuring the fracturing effect, realize in-situ directional fracturing, and achieve the purpose of reducing the number of mining drill holes and improving the drilling mining efficiency.

[0004] "Microwave-assisted pressure relief and support method for deep hard rock engineering" with the patent number CN202010768522.1. This method pre-drills the heading face, introduces microwaves into the holes to achieve primary fracturing of the surrounding rock formations, and then injects an expansive fracturing agent to achieve secondary fracturing. Although this rock-breaking method can effectively achieve secondary crack development, there are still the following deficiencies. First, the microwave heating method of this method is full-borehole heating, and the selective heating characteristic of microwaves causes fractures to develop randomly within its radiation surface, making it impossible to achieve a directional effect. The uncontrollability of the fracturing range and direction leads to large energy consumption while the damage range is relatively small. Second, the slurry injection method is direct injection, which is only effective for bottom-hole drilling. For top-hole drilling, the high-temperature state of the hole-wall rock formations after microwave heating will accelerate the hydration reaction rate. If the drilling is deep, the slurry will first accumulate at the hole mouth and react quickly to block the grouting port, while the bottom-hole rock formations are not fractured by expansion, resulting in uneven borehole fracturing, poor fracturing effect, and inability to guarantee the fracturing range. Third, this method requires the microwave and grouting equipment to be cycled in and out to complete radiation and grouting, with low efficiency and many processes. Fourth, the transmission of microwaves in the borehole uses the hole wall as the transmission and reflection channel, with low efficiency and large losses, and the energy received by the radiation area is uneven, resulting in uneven secondary fracturing effects after fracture development and fracturing agent injection. Fifth, the radiation object of this method is the bottom of the borehole, and the fracture network only forms at the bottom, making it impossible to achieve fracturing in the shallow part of the borehole.

[0005] "Device and method for microwave irradiation combined with dry ice fracturing to extract shale gas" with the patent number CN202110818807.6 and "Method for synergistically constructing an artificial hot reservoir for enhanced geothermal system using microwave radiation and dry ice jet" with the patent number CN202210814840.6. Both of these rock-breaking methods use microwaves to pre-heat the hole-wall rock formations in the wellbore and then inject dry ice to achieve thermal shock fracturing. Although this combined rock-breaking method can effectively improve the degree of rock formation damage, there are still the following deficiencies. First, the low-temperature shock fractures mainly develop on both sides of the main fractures, and there is no obvious beneficial effect on the expansion of the main fractures and the increase in the fracturing range. Second, dry ice as a cooling means achieves fracturing through heat conduction and only forms an impact on the surface, with low damage effect and limited impact range. Third, after low-temperature shock, dry ice cannot effectively support the generated fractures, and may cause the fractures to close under the action of surrounding rock stress. Fourth, the fractures generated by this microwave radiation method and the low-temperature shock process are relatively random, and the fracturing direction and fracturing range are not controllable. Fifth, during deep-well operations, there is no protection device outside the pipeline, and it is very likely that the borehole will collapse, resulting in pipeline interruption and abandonment of the borehole.

[0006] "A combined rock-breaking method using microwave action and carbon dioxide blasting for deep metal ores" with the patent number CN202410969226.6. This method fixes the sleeve by arranging multiple annular pockets outside the sleeve, and then performs microwave radiation heating on the hole wall in segments. After the temperature rises, liquid carbon dioxide is quickly injected, and the high temperature of the hole wall is used to cause its phase change to generate cracks. This method has the following deficiencies. Firstly, this method uses carbon dioxide blasting as a secondary fracturing method, mainly achieving fracturing through gas shock waves. After the microwave generates cracks, a buffer layer will form in the crack space, reducing the fracturing effect. Secondly, the phase change speed of carbon dioxide in this method is determined by the hole wall temperature. After the liquid carbon dioxide is injected, it will be accompanied by a temperature reduction effect, and the timing of the phase change reaction cannot be determined. Moreover, there is a problem of uneven damage during deep hole operation, and the overall controllability is poor. Thirdly, in this combined rock-breaking method, the fracturing effect and range of carbon dioxide blasting are higher than those of microwave, resulting in the fracturing range being mainly determined by the amount of carbon dioxide used, with a smaller damage range, and there is not much relevance and interaction between the two in terms of fracturing. Fourthly, the direct contact between the annular pocket of this method and the high-temperature hole wall rock formation leads to a high damage rate. Moreover, microwave is a penetrative heating method. When radiating in a closed space, it will be reflected and then heat the water in the pocket, and the high temperature and steam generated will also cause damage to the pocket. Fifthly, when segmenting this method, the microwave device and the carbon dioxide injection device need to be repeatedly taken out and pushed in. If deep hole operation is adopted, the workload is large and the efficiency is low.

[0007] "A continuous hard rock mining equipment and its application method" with the patent number CN202310697352.6. This method forms micro-cracks through supercritical carbon dioxide, and then uses microwave to accelerate the reaction to weaken the rock formation, and finally realizes mining through the cutting system. This method mainly has the following deficiencies. Firstly, the main fracturing means of this method is supercritical carbon dioxide, and microwave is only a catalytic reaction device. 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 has few primary cracks, the reduction of the contact area will cause a significant reduction in the fracturing efficiency, and the applicability is poor. Secondly, supercritical carbon dioxide belongs to non-polar molecules with extremely low dielectric loss and relatively poor dielectric properties. Microwave catalysis mainly targets polar molecular systems. Therefore, the absorption ability of supercritical carbon dioxide to microwave is weak, and the catalytic means may have poor effects, and overall the fracturing efficiency is low. Thirdly, this fracturing method is extremely dependent on the porosity and the development of primary cracks, so it is impossible to achieve controllability of the fracturing range and direction, and at the same time, it is easy to cause large differences in the fracturing effects in different regions of the hole. Fourthly, the supercritical carbon dioxide injection device and the microwave radiation device also extend into the drill hole for operation, and this method does not consider the damage of supercritical carbon dioxide to the microwave device during injection and its prevention method.

[0008] "A Microwave Heating Cooperative Water Cooling Fracturing Induced Caving Mining Method" with the patent number CN202310318166.7. This method involves performing microwave radiation in a borehole, fracturing and heating the rock formation, injecting water for low-temperature impact, and finally achieving borehole mining through the natural caving method. The following are the deficiencies of this method. Firstly, the secondary fracturing medium of this method is water, which can only develop fractures through low temperature, resulting in poor fracturing effect, and the fractures may close under the action of surrounding rock stress after formation. Secondly, this method also only uses temperature impact for fracturing, with poor controllability of the fracturing range and direction, and poor fracturing uniformity of the borehole wall rock formation. Thirdly, this method requires continuous pushing and pulling of the device to achieve the cyclic fracturing of microwave and water in the same borehole, with high operation intensity and low fracturing efficiency, and the defects are particularly obvious when the borehole depth is large. Fourthly, the borehole wall around the microwave radiation port is the radiation surface, and the borehole wall rock formation is uneven. When serving as the transmission and reflection channel, the energy received by the radiation area is uneven, with low efficiency, unable to achieve the directional effect, and no controllability of the fracturing range and direction. Summary of the Invention

[0009] In view of the problem that when microwaves are used for drilling and mining hard ore rocks, due to transmission loss and power limitation, the fractures generated by microwaves not only have a relatively small range but also poor connectivity with each other, the present invention provides a microwave-expansive agent in-situ fracturing device and method for drilling and mining ore rocks.

[0010] The present invention utilizes the temperature gradient between minerals after microwave heating of ore rocks to directionally form initial fractures, and then injects static expansive agent slurry into the fractures to achieve in-situ secondary fracturing. It can not only extend the fracture length and increase the damage range, but also promote the connection of fractures through the expansion pressure to form a large-area connected fracture network. In addition, the device transmits microwaves through a rectangular waveguide in cooperation with a segmented circular waveguide, greatly reducing the energy loss in the borehole and ensuring uniform radiation of each section of the borehole wall rock formation. At the same time, by grading the liquid outlet pressure to control the segmented injection of the slurry from deep to shallow, the consistency of the rock formation under load is promoted. It has the characteristics of directional fracturing and position controllability.

[0011] The present invention adopts the following technical solutions: A microwave-expansive agent in-situ fracturing device for drilling and mining ore rocks, comprising a microwave system, a liquid injection system, and a sleeve system; The microwave unit includes a microwave power source and a three-port circulator. The output end of the microwave power source is connected to the input end of the three-port circulator. The right-angle output end of the three-port circulator is connected to a water load, and the other output end is connected to a three-pin tuner. The output end of the three-pin tuner is sequentially connected to a right-angle bend waveguide and a rectangular waveguide. The rectangular waveguide extends into the borehole. A plurality of circular waveguides are provided on the rectangular waveguide, and the circular waveguides are symmetrically arranged on both sides of the rectangular waveguide along the length direction and are equally spaced.

[0012] 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 mixing motor is provided at the top of the mixing barrel, the output end of the mixing motor is connected with a mixing impeller, the bottom of one side of the mixing barrel is connected with 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.

[0013] Furthermore, the sleeve system includes a housing located in the drill hole, a rectangular waveguide is located inside the housing, a vibrator is provided at the top of the housing, several backflow prevention hole-sealing devices are provided on the outer side of the housing, the backflow prevention hole-sealing devices and the circular waveguide are arranged alternately, and several slurry outlet ports are provided on the side wall of the housing.

[0014] Furthermore, a coaxial inner core is provided at the center of the circular waveguide along the axial direction, and a wave-transmitting plate is provided at the output port of the circular waveguide.

[0015] Furthermore, the backflow prevention hole-sealing device is located at the center between two adjacent circular waveguides. The backflow prevention hole-sealing device is an umbrella-shaped hollow circular ring structure. The diameter of the outer ring of the hollow circular ring is 20 mm smaller than the diameter of the drill hole. The outer surface of the backflow prevention hole-sealing device is wrapped with a basalt fiber cloth layer, and a pneumatic telescopic screw is provided at the bottom of the backflow prevention hole-sealing device.

[0016] Furthermore, a safety valve with adjustable pressure is provided at the slurry outlet port, and the opening pressure of the safety valve decreases successively from the shallow part to the deep part of the drill hole.

[0017] Furthermore, the slurry outlet pipe of the grouting pump is respectively connected with the slurry outlet ports of the housing through a flow dividing valve, and the air compressor is respectively connected with the pneumatic telescopic screw and the vibrator through an air inlet pipe.

[0018] A method for drilling and mining ore and rock includes the following steps: S1. Determine the microwave radiation parameters according to the geological conditions of the ore deposit and the predetermined drilling and mining plan. Drill the mining drill holes in advance. The mining drill holes are arranged in a rectangular pattern with the same spacing between rows and columns. After cleaning the sludge in the holes, mark the radiation direction of the circular waveguide at the hole opening. The radiation angles are 45° and 135°, and they are arranged in an oblique orthogonal staggered manner, that is, ensure that the radiation angles of this drill hole are different from those of the 4 upper, lower, left, and right drill holes to maximize the crack coverage area; S2. Adjust the pneumatic telescopic screw of the backflow prevention hole-sealing device to a suitable position according to the drill hole diameter to ensure that the outer side of the backflow prevention hole-sealing device is closely attached to the hole wall when placed in the drill hole; S3. Connect the rectangular waveguide, circular waveguide, and each pipeline to the inside of the housing in sequence. The pipeline is led out from the hole opening through the interlayer between the rectangular waveguide and the housing and is respectively connected to the corresponding positions; S4. Push the outer casing into the borehole, rotate the output port of the circular waveguide to the predetermined fracturing direction and position according to the radiation direction identification at the hole opening, and support and fix it through the check valve hole sealing device; S5. Turn on the microwave power source, preheat for 30 s, and then start to output microwaves. The incident wave performs continuous directional focusing radiation on the rock formation of the hole wall according to the predetermined time through the cooperation of the rectangular waveguide, circular waveguide and coaxial inner core; S6. Turn on the stirring impeller, pour water and static expanding agent into the mixing barrel according to the water-cement mass ratio of 1:3 and mix evenly. At the same time, adjust the pressure of the grouting pump for standby; S7. After the microwave radiation is completed according to the predetermined time, the temperature of the rock formation of the hole wall increases significantly, and initial cracks are formed directionally in the radiation direction. At this time, immediately open the slurry outlet pipe, and the slurry enters the pipeline in the hole through the shunt valve. The pipeline pressure increases rapidly, and the safety valve at the first slurry outlet at the deep part of the borehole opens, and the slurry begins to be injected into the initial cracks of the first section of the hole wall. The pipeline pressure drops. At this time, the slurry temperature is relatively low, causing the first temperature shock to the deep rock formation and promoting the further development of the cracks; S8. After the rock formation of the first section of the hole wall absorbs the slurry to saturation, the pipeline pressure increases again until the safety valve at the second liquid outlet opens, and the slurry is injected into the initial cracks of the second section to further fracture the rock formation of the hole wall; S9. Repeat steps S7 - S8 until the rock formation of the hole wall absorbs the slurry to the saturation state. At this time, the high temperature of the rock formation promotes the acceleration of the hydration reaction rate of the expanding agent. The development form of the initial cracks under the action of the expansion pressure is mainly expansion, and the crack length, the number of connected cracks and the fracturing range all increase significantly, and finally a large-area connected crack network with the radiation direction as the main crack is formed; S10. After the fracturing is completed, due to the increase in the crack volume, the space in the hole expands accordingly, and the powder product after the reaction of the expanding agent will be loosened. At this time, turn on the air compressor, operate the vibrator and retract the pneumatic telescopic screw rod, and use vibration to compact the powder to realize the separation of the outer casing from the hole wall, and slowly take out the outer casing.

[0019] The beneficial effects of the present invention are as follows: 1. The present invention generates initial fractures through microwave radiation to achieve a directional effect, and then a static crack agent is injected to achieve in-situ secondary fracturing. The fractures generated by microwaves are numerous but their connectivity cannot be guaranteed. The fracture development form of the static crack agent is mainly the crack extension caused by tensile failure, and the extension direction is the weak surface direction. Therefore, after being used in combination, the slurry enters the initial fractures generated by microwaves, and the expansion pressure significantly increases the aperture and length of the fractures, enabling a large number of fractures to be interconnected to form a large-area fracture network, increasing the damage range and degree of a single hole. In addition, the object of the secondary fracturing is the rock formation at the tip of the fracture, that is, the secondary fractures start to expand on the basis of the microwave fracturing range (initial fractures), and the combined fracturing range can be calculated by superposition. In the other combined rock-breaking forms, the object of the secondary fracturing is still the borehole surface, and the fracturing range is only the maximum value of one of the methods, without achieving the superposition effect. Moreover, the formation of the initial fractures is likely to become a buffer layer, greatly reducing the effective damage range of the shock wave type fracturing method.

[0020] 2. Both the microwave and the static crack agent in the present invention can achieve low vibration or no vibration during the destruction process, and can also achieve the effect of low-vibration breaking during combined crushing. There is no impact and vibration, and there is no noise and dust pollution at the same time. In addition, the rock formation on the borehole wall is subjected to the cyclic temperature shock of high temperature (microwave radiation) - low temperature (slurry soaking) - high temperature (hydration reaction) during the combined fracturing process, and the degree of borehole wall damage is high, which can achieve the purpose of efficient and green mining.

[0021] 3. In the present invention, the microwave transmission in the hole of the rock-breaking device uses a rectangular waveguide, and the output uses a circular waveguide. All transmission channels are standard waveguide components, and the transmission efficiency is much higher than that of arranging the output port at the hole mouth. Through the transmission method of reflection by the borehole wall, the uniform output of microwave energy in the borehole can be realized, avoiding the problem that the radiation intensity received by the rock formations at different depths of the borehole is inconsistent.

[0022] 4. During the fracturing process of this combined rock-breaking method, it can ensure that the acting forces and the final fracturing degrees received by each section of the rock formation are basically the same, achieving the effect of controllable fracturing range, and through this rock-breaking device, two in-situ fracturings can be completed in one operation.

[0023] 5. The static crack agent is injected in a segmented manner from deep to shallow to prevent the shallow liquid outlet from being blocked in advance due to the high temperature of the rock formation on the borehole wall. The static crack agent will form solid powder after reaction, which can effectively support the fractures and prevent the fractures from closing.

[0024] 6. The segmented circular waveguide is equipped with a coaxial inner core, which has the function of guiding microwave to focus on one point for radiation. The single-point energy density is high, and the connection between the output ports of two or more segments is beneficial to directional fracturing.

[0025] 7. By arranging the boreholes in an oblique orthogonal interleaved method and combining with the fracture network formed by the directional fracturing device, the voids between the boreholes can be maximally covered, ensuring the fracturing effect while increasing the row spacing between the boreholes, effectively improving the borehole fracturing efficiency and saving the borehole cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is the device structure diagram of the present invention; Figure 2 is the installation schematic diagram of the device of the present invention in the borehole; Figure 3 is Figure 1 the sectional view taken along the A-A direction of Figure 4 is Figure 1 the sectional view taken along the B-B direction of Figure 5 is the schematic diagram of the arrangement of the microwave radiation directions of each borehole according to the oblique orthogonal interleaved method; Wherein: 1 - microwave power source; 2 - three-port circulator; 3 - water load; 4 - three-pin tuner; 5 - right-angle bend waveguide; 6 - rectangular waveguide; 7 - circular waveguide; 8 - coaxial inner core; 9 - wave-transmitting plate; 10 - stirring barrel; 11 - water inlet pipe; 12 - stirring motor; 13 - stirring impeller; 14 - slurry suction pipe; 15 - grouting pump; 16 - slurry outlet pipe; 17 - flow divider valve; 18 - pressure gauge; 19 - motor; 20 - air compressor; 21 - air inlet pipe; 22 - outer shell; 23 - vibrator; 24 - check valve for hole sealing; 25 - slurry outlet; 26 - pneumatic telescopic screw; 27 - safety valve; 28 - borehole; 29 - ore and rock to be mined. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The present invention will be further described in conjunction with the accompanying drawings.

[0028] As shown in the figure, a microwave-expansive agent in-situ fracturing device for mining ore and rock by borehole includes a microwave system, a liquid injection system and a sleeve system; The microwave unit includes a microwave power source 1 and a three-port circulator 2. The output end of the microwave power source 1 is connected to the input end of the three-port circulator 2. The right-angle output end of the three-port circulator 2 is connected to a water load 3, and the other output end is connected to a three-pin tuner 4. The output end of the three-pin tuner 4 is sequentially connected to a right-angle bend waveguide 5 and a rectangular waveguide 6. The rectangular waveguide 6 extends into the 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 equally spaced; The sleeve system includes a housing 22 located in a borehole 28, a rectangular waveguide 6 located within the housing 22, a vibrator 23 provided at the top end of the housing, a number of non-return hole-sealing devices 24 provided on the outer side of the housing 22, the non-return hole-sealing devices 24 and a circular waveguide 7 being arranged alternately, and a number of slurry outlets 25 provided on the side wall of the housing 22.

[0029] The output microwave frequency of the microwave power source 1 is 2450 MHz, and the maximum power is continuously adjustable up to 15 kW; the three-port circulator 2, water load 3, three-pin tuner 4, right-angle bend waveguide 5, and rectangular waveguide 6 are all WR340 standard waveguide components, made of aluminum, with flange connections. The size of the rectangular waveguide 6 is 86.36 mm in length and 43.18 mm in width.

[0030] The liquid injection system includes a mixing barrel 10 and a grouting pump 15. A water inlet pipe 11 is provided at the top end on one side of the mixing barrel 10, a mixing motor 12 is provided at the top of the mixing barrel 10, the output end of the mixing motor 12 is connected to a mixing impeller 13, the bottom end on one side of the mixing barrel 10 is connected to the grouting pump 15 through a slurry suction pipe 14, a slurry outlet 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.

[0031] The circular waveguide 7 is provided with a coaxial inner core 8 along the axial center, which is made of an electrically conductive material. A wave-transparent plate 9 is provided at the output port of the circular waveguide 7 for sealing and waterproofing, made of a phosphate-based composite wave-transparent material, and the wave transmission rate is not less than 80%.

[0032] The non-return hole-sealing device 24 is located at the center between two adjacent circular waveguides 7. The non-return hole-sealing device 24 is an umbrella-shaped hollow circular ring structure. The diameter of the outer ring of the hollow circular ring is 20 mm smaller than the diameter of the borehole 28, and it is welded and fixed to the housing 22 through the inner ring of the hollow circular ring. The skeleton is made of carbon steel. The outer surface of the non-return hole-sealing device 24 is wrapped with a basalt fiber cloth layer, and the wrapping thickness is based on tightly fitting the borehole wall (not less than 10 mm). A pneumatic telescopic screw 26 is provided at the bottom of the non-return hole-sealing device 24 to ensure support and sealing. The basalt fiber cloth is a flexible material with high strength, water-repellent, and high-temperature resistant (not less than 700 °C) characteristics.

[0033] A safety valve 27 with adjustable pressure is provided at the slurry outlet 25. The opening pressure of the safety valve 27 decreases successively from the shallow part to the deep part of the borehole 28, ensuring that the opening pressure of the safety valve in the deep part is lower than that in the shallow part, so that the slurry is preferentially injected into the deeper section to prevent the slurry in the shallow part from quickly reacting and blocking the pipeline.

[0034] The slurry outlet pipe 16 of the grouting pump 15 is respectively connected to the slurry outlet 25 of the housing 22 through a flow control 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.

[0035] A method for drilling and mining ore and rock, comprising the following steps: S1. Determine the microwave radiation parameters according to the geological conditions of the ore deposit and the predetermined drilling and mining plan. Drill the mining holes in advance. The mining holes are arranged in a rectangular pattern with the same interval and row spacing. After cleaning the silt in the holes, mark the radiation direction of the circular waveguide at the hole opening. Two radiation angles of 45° and 135° are adopted, and they are arranged obliquely and orthogonally in a staggered manner. Taking the diagonal line of the rectangle as the reference line, the angles are set alternately row by row. The circular waveguide is in an "X" shape, that is, it is ensured that the radiation angles of any drilling hole are different from those of its upper, lower, left, and right 4 drilling holes, and the angles are the same as those of its diagonal oblique drilling holes, so as to maximize the fracture coverage area; S2. Adjust the pneumatic telescopic screw 26 of the check valve sealing device 24 to a suitable position according to the borehole diameter, and ensure that the outer side of the check valve sealing device 24 is closely attached to the hole wall when it is placed in the drilling hole 28; S3. Connect the rectangular waveguide 6, the circular waveguide 7 and each pipeline to the inside of the housing 22 in sequence. The pipeline is led out from the hole opening through the interlayer between the rectangular waveguide 6 and the housing 22 and is respectively connected to the corresponding positions; S4. Push the housing into the drilling hole 28, rotate the output port of the circular waveguide 7 to the predetermined fracturing direction and position according to the radiation direction mark at the hole opening, and support and fix it through the check valve sealing device 24; S5. Turn on the microwave power source 1 and preheat for 30 s, and then start to output microwaves. The incident wave performs continuous directional focusing radiation on the rock formation of the hole wall according to the predetermined time through the cooperation of the rectangular waveguide 6 and the circular waveguide 7 with the coaxial inner core 8; S6. Turn on the stirring impeller 13, pour water and the static fracturing agent into the stirring barrel 10 according to the water-cement mass ratio of 1:3 and mix evenly. At the same time, adjust the pressure of the grouting pump 15 for standby; the static fracturing agent is an inorganic compound mainly composed of calcium oxide, which forms a slurry when mixed with water and crushes the rock by volume expansion through the hydration reaction.

[0036] S7. After the microwave radiation is completed according to the predetermined time, the temperature of the rock formation of the hole wall increases significantly, and initial fractures are formed directionally in the radiation direction. At this time, immediately open the slurry outlet pipe 16, and the slurry enters the pipeline in the hole through the flow dividing valve 17. The pipeline pressure increases rapidly, and the safety valve 27 at the first slurry outlet at the deep part of the drilling hole opens, and the slurry begins to be injected into the initial fractures of the first section of the hole wall. The pipeline pressure drops. At this time, the slurry temperature is relatively low, causing the first temperature shock to the deep rock formation and promoting the further development of the fractures; S8. After the first section of the hole wall rock formation absorbs the slurry to saturation, the pipeline pressure increases again until the safety valve at the second liquid outlet opens, and the slurry is injected into the initial fractures of the second section to further fracture the hole wall rock formation; S9. Repeat steps S7 - S8 until the rock formation on the hole wall has absorbed the grout to saturation. At this time, the high temperature of the rock formation accelerates the hydration reaction rate of the expansive agent. The main form of the initial crack development under the action of the expansion pressure is expansion. The crack length, the number of connected cracks, and the fracturing range all increase significantly, and finally a large - area connected crack network with radial - direction - dominated cracks is formed. S10. After the fracturing is completed, due to the increase in the crack volume, the space in the hole expands accordingly, and the powder product after the reaction of the expansive agent will become loose. At this time, turn on the air compressor 20, operate the vibrator 23 and retract the pneumatic telescopic screw 26, use vibration to compact the powder, realize the separation of the outer shell from the hole wall, and slowly take out the outer shell.

[0037] Example A certain iron mine adopts the open - pit mining method of level - by - level stratification. The ore deposit type is banded quartz - type hematite. The ore is dense and has a high strength, with a maximum compressive strength of 203.9 MPa. According to the geological data, the main mineral components of the quartz - type hematite are hematite, quartz, wustite, etc.

[0038] (1) According to the mine geological data, determine the size of the ore body area to be drilled and tested as 4m×7m, and the single - time mining depth is 10m. Take large rock samples in the ore deposit for pre - experiments. After irradiating with a microwave power of 15 kW for 3 min, macroscopic cracks can appear in the rock samples. After injecting the expansive agent at this time, the reaction time is about 70 min, and the single - hole fragmentation range is about 780 mm.

[0039] (2) Based on the pre - experimental results, comprehensively determine the microwave - expansive agent combined fracturing plan as follows: the row - spacing and column - spacing between drill holes are 1.5 m, there are 5 drill holes in each row, 3 rows are arranged, a total of 15 drill holes. Make 15 sets of outer shells of the sleeve system. The drill - hole depth is 10 m, and they are drilled vertically on the ore - deposit surface. The microwave power is 15 kW, the radiation time is 3 min, and the grout is injected immediately after the radiation. The segment length is 1 m, a total of 10 segments. There are 2 circular waveguides in each segment, with a spacing of 1 m, a total of 20. There are 10 slurry outlets in total. Set the pressure of the first slurry outlet (the deepest part of the drill hole) to 0.5 MPa, and increase by 0.5 MPa for each segment. Then the tenth segment (the shallowest part of the drill hole) is 5 MPa. The drill - hole diameter is 135 mm, the outer diameter of the sleeve is 90 mm, the total diameter after the reverse - check hole - sealing device supports is 114 mm, and the thickness of the basalt - fiber cloth wrapping is 22 mm; (2) Install all the sleeve systems into the drill holes, check the sealing performance, ensure that the reverse - check hole - sealing device is close to the hole wall, and rotate the sleeve to the predetermined fracturing position; (3) First, connect the water pipe, slurry - suction pipe, liquid - injection pipeline, air - inlet pipeline, and waveguide components to the predetermined position of the No. 1 drill hole for standby; (4) Turn on the stirring barrel, inject water and static expansive agent in proportion, stir evenly and set aside. The stirring impeller needs to keep stirring to prevent sedimentation; After turning on the microwave power source and preheating, turn on the microwave radiation and set the radiation time to 3 min; (6)Immediately start grouting after the radiation is completed. The grout first enters the first section with a relatively low opening pressure, and gradually enters the micro-cracks generated by microwave radiation. After saturation, the pressure rises, the valve of the second section opens, and the grouting starts to circulate to the tenth section. At this time, the borehole is impacted by the low temperature of the grout, and the cracks will further develop. It is necessary to ensure that the pressure of the grouting pump is not less than 5 MPa. When the pressure is maintained at a high level for a certain period of time, the crack development stops, indicating that the borehole reaches the saturation state, and the grouting is stopped; (7)Disassemble the external pipeline and waveguide components outside the hole and connect them to the No. 2 borehole. Repeat steps 4-6 to fracture all boreholes in turn; (8)About 2 h after the grouting is completed, after the borehole experiences temperature shock and expansion extrusion, a large-area crack network with cracks mainly in the direction of segmented circular waveguide radiation is formed. The boreholes are interconnected with each other to realize the in-situ combined fracturing of the mining area by microwave and expansion agent, which not only causes no pollution but also greatly reduces the ore strength; (9)The formation of cracks increases the volume of the borehole. Subsequently, compact the powder with a vibrator and remove the sleeve system.

Claims

1. A microwave-expansion agent in-situ fracturing device for drilling and mining ore and rock, characterized in that: It includes a microwave system, a liquid injection system and a sleeve system; The microwave unit includes a microwave power source (1) and a three-port circulator (2). The output end of the microwave power source (1) is connected to the input end of the three-port circulator (2). The right-angle output end of the three-port circulator (2) is connected to a water load (3), and the other output end is connected to a three-pin tuner (4). The output end of the three-pin tuner (4) is sequentially connected to a right-angle bend waveguide (5) and a rectangular waveguide (6). The rectangular waveguide (6) extends into a drill hole (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 equally spaced; The sleeve system includes a housing (22) located in the drill hole (28). The rectangular waveguide (6) is located inside the housing (22). A vibrator (23) is provided at the top of the housing. A plurality of check hole-sealing devices (24) are provided on the outer side of the housing (22). The check hole-sealing devices (24) and the circular waveguides (7) are arranged alternately. A plurality of slurry outlets (25) are provided on the side wall of the housing (22).

2. The microwave-expansion agent in-situ fracturing device for drilling and mining ore and rock according to claim 1, characterized in that: 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 mixing motor (12) is provided at the top of the mixing barrel (10). The output end of the mixing motor (12) is connected to a mixing impeller (13). The bottom of one side of the mixing barrel (10) is connected to the grouting pump (15) through a slurry suction pipe (14). A slurry outlet 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). An air compressor (20) is provided on one side of the grouting pump (15).

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

4. The in-situ fracturing device for microwave-expansion agent of drilling and mining ore and rock according to claim 3, characterized in that: The check hole-sealing device (24) is located at the center between two adjacent circular waveguides (7). The check hole-sealing device (24) 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 drill hole (28). The outer surface of the check hole-sealing device (24) is wrapped with a basalt fiber cloth layer. A pneumatic telescopic screw (26) is provided at the bottom of the check hole-sealing device (24).

5. The microwave-expansion agent in-situ fracturing device for drilling and mining ore and rock according to claim 4, characterized in that: A safety valve (27) with adjustable pressure is provided at the slurry outlet (25). The opening pressure of the safety valve (27) decreases sequentially from the shallow part to the deep part of the drill hole (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 flow dividing valve (17). The air compressor (20) is respectively connected to the pneumatic telescopic screw (26) and the vibrator (23) through an air inlet pipe (21).

6. A method for drilling and mining ore rock using the microwave-expansion agent in-situ fracturing device according to claim 5, characterized in that: It includes the following steps: S1. Determine the microwave radiation parameters according to the geological conditions of the ore deposit and the predetermined drilling mining plan. Drill the mining boreholes in advance. The mining boreholes are arranged in a rectangular pattern with the same spacing between rows and columns. After cleaning the silt in the boreholes, mark the radiation direction of the circular waveguide at the orifice. Two radiation angles, 45° and 135°, are used and arranged in an oblique orthogonal staggered manner, that is, ensure that the radiation angles of this borehole are different from those of the 4 boreholes above, below, left, and right to maximize the fissure coverage area. S2. Adjust the pneumatic telescopic screw (26) of the check valve sealing device (24) to a suitable position according to the borehole diameter to ensure that the outer side of the check valve sealing device (24) closely adheres to the borehole wall when placed in the borehole (28). S3. Connect the rectangular waveguide (6), circular waveguide (7), and each pipeline to the inside of the housing (22) in sequence. The pipeline is led out from the orifice through the interlayer between the rectangular waveguide (6) and the housing (22) and connected to the corresponding positions respectively. 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 radiation direction mark at the orifice, and support and fix it through the check valve sealing device (24). S5. Turn on the microwave power source (1) and preheat for 30 s, then start to output microwaves. The incident wave performs continuous directional focusing radiation on the borehole wall rock layer through the cooperation of the rectangular waveguide (6), circular waveguide (7), and coaxial inner core (8) for a predetermined time. S6. Turn on the stirring impeller (13), pour water and static expansion agent into the mixing barrel (10) according to the water-cement mass ratio of 1:3 and mix evenly. At the same time, adjust the pressure of the grouting pump (15) for standby. S7. After the microwave radiation is completed according to the predetermined time, the temperature of the borehole wall rock layer increases significantly, and initial fissures are formed directionally in the radiation direction. At this time, immediately open the slurry outlet pipe (16). The slurry enters the pipeline in the borehole through the flow dividing valve (17). The pipeline pressure increases rapidly, and the safety valve (27) at the first slurry outlet at the deep part of the borehole opens. The slurry starts to be injected into the initial fissures on 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 layer and promoting the further development of the fissures. S8. After the first section of the borehole wall rock layer absorbs the slurry to saturation, the pipeline pressure increases again until the safety valve at the second liquid outlet opens, and the slurry is injected into the second section of the initial fissures to further fracture the borehole wall rock layer. S9. Repeat steps S7 - S8 until the borehole wall rock layer absorbs the slurry to saturation. At this time, the high temperature of the rock layer promotes the acceleration of the hydration reaction rate of the expansion agent. The development form of the initial fissures under the action of the expansion pressure is mainly expansion, and the fissure length, the number of connected fissures, and the fracturing range all increase significantly, finally forming a large-area connected fissure network with the radiation direction as the main fissure. S10. After the fracturing is completed, due to the increase in the fissure volume, the space in the borehole expands accordingly, and the powder product after the reaction of the expansion agent will be loosened. At this time, turn on the air compressor (20), operate the vibrator (23), and retract the pneumatic telescopic screw (26). Use vibration to compact the powder to realize the separation of the housing from the borehole wall, and slowly take out the housing.

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