A high-cold mine liquid oxygen-nitrogen composite phase change rock fracturing device and a rock fracturing method

Abstract

This invention discloses a liquid oxygen-nitrogen composite phase change rock-fracture device and method for use in cold-climate mines, relating to the field of mining and blasting engineering technology. It includes a first storage tube with a partition plate installed on its inner wall, and an energy storage tube located on one side of the partition plate on the inner wall of the first storage tube. This liquid oxygen-nitrogen composite phase change rock-fracture device and method for cold-climate mines effectively blocks heat conduction from the external cold environment to the energy storage tube by filling the hollow area with vacuum insulation material or maintaining a vacuum state, significantly reducing the evaporation loss of the liquid oxygen-nitrogen mixture. Simultaneously, by inserting one end of the input pipe into the bottom of the absorbent, and cooperating with the shut-off valve on the exhaust pipe, the mixture is allowed to permeate upwards from the bottom of the absorbent and completely expel air from the energy storage tube. This achieves the effect of maintaining the mixture in a liquid state for a long time in cold-climate environments, with no air residue after injection, and a stable and reliable phase change reaction.

Description

Technical Field

[0001] This invention relates to the field of mining and blasting engineering technology, specifically to a liquid oxygen-nitrogen composite phase transformation rock-fracture device and method for use in cold-climate mines. Background Technology

[0002] In the field of mining and blasting engineering, with the increase in mining depth and the expansion of operating environments to high-altitude and cold regions, traditional blasting technology has encountered unprecedented challenges. In high-altitude and cold environments, the chemical properties of conventional explosives become unstable due to the low temperature, resulting in a significant decrease in blasting efficiency and an increase in operational safety risks. In addition, the unique permafrost layer and hard rock structure of high-altitude and cold regions make it difficult for traditional blasting methods to achieve ideal fragmentation effects, further restricting the efficiency and economic benefits of mining. Therefore, exploring new blasting technologies adapted to high-altitude and cold environments has become a hot topic and a difficult point in this field of research.

[0003] However, the problem with existing technologies is how to effectively maintain the stability of liquid oxygen-nitrogen mixtures under extremely cold conditions to reduce evaporation losses and ensure that no air remains in the rock-fracturing device during the injection process, thereby achieving stable and reliable phase change reactions. Liquid oxygen and liquid nitrogen mixtures are considered a potentially efficient means of rock fracturing in extremely cold mines because they can release huge amounts of energy during phase change. However, the extremely cold environment accelerates the evaporation of the mixture, which not only reduces the rock-fracturing efficiency but may also cause abnormal internal pressure of the device due to the accumulation of evaporated gas, increasing operational risks. At the same time, air residues during the injection process can interfere with the uniformity of the phase change reaction and affect the consistency of the rock-fracturing effect. Therefore, improvements are needed. Summary of the Invention

[0004] The purpose of this invention is to provide a liquid oxygen-nitrogen composite phase change rock-fracture device and method for use in cold-climate mines, in order to solve the problems in the prior art where liquid oxygen-nitrogen mixture is easily lost through evaporation in cold-climate environments and air is easily left behind during the injection process, leading to unstable phase change reactions.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a liquid oxygen-nitrogen composite phase transformation rock-fracture device for high-altitude cold mines, comprising a first storage tube, a partition plate installed on the inner wall of the first storage tube, an energy storage tube disposed on one side of the inner wall of the first storage tube located on the partition plate, and fixing rings installed on both sides of the surface of the energy storage tube, the fixing rings being installed on the inner wall of the first storage tube, and a hollow area being formed between the first storage tube and the energy storage tube;

[0006] The inner wall of the energy storage tube is filled with an absorbent. An injection tube is installed at the top of the first storage tube, and a first one-way valve is installed on the inner wall of the injection tube. An input tube is installed at the bottom of the injection tube, and one end of the input tube is inserted into the absorbent in the energy storage tube. An exhaust tube is installed at the top of the first storage tube, and a connecting tube is installed at the bottom of the exhaust tube. One end of the connecting tube is inserted into the inner wall of the energy storage tube, above the absorbent. A shut-off valve is installed on the inner wall of the exhaust tube.

[0007] Furthermore, a first electrical connector is installed at the top of the first storage tube, and an explosion-proof junction box is installed at the bottom of the first electrical connector. A wire is electrically connected to the bottom of the explosion-proof junction box, and an ignition head is electrically connected to the bottom of the wire. The ignition head is located on the inner bottom wall of the absorbent, and a power transmission head is electrically connected to the bottom of the wire.

[0008] Furthermore, a threaded mounting groove is provided at the bottom end of the first storage tube, and the threaded mounting groove is sleeved on the outside of the power transmission head.

[0009] Furthermore, a threaded connector is installed at the top of the first storage tube, and the threaded connector is sleeved on the outside of the injection tube and the exhaust tube.

[0010] Furthermore, a protective cover is threaded onto the surface of the threaded connector, and a connecting wire is electrically connected to the top of the protective cover.

[0011] Furthermore, a second storage tube is threadedly connected to the bottom end of the first storage tube.

[0012] Furthermore, a second electrical connector is provided at the top of the second storage tube, and the second electrical connector is electrically connected to the power transmission head.

[0013] Furthermore, the first storage tube and the energy storage tube are made of modified nylon, high-density polyethylene or thin-walled stainless steel; the modified nylon has a notched impact strength ≥10kJ / m² at -40℃, and the thin-walled stainless steel has a wall thickness of 0.5~1.5mm.

[0014] Furthermore, the absorbent is one or more of the following: multi-layer roll paper, wood chip pressed rod, or porous foam metal impregnated with combustible resin, with a porosity of 40% to 70% and a moisture content of ≤1%.

[0015] A liquid oxygen-nitrogen composite phase transformation fracturing method for high-altitude and cold-climate mines includes the following steps:

[0016] S1. Insert the energy storage tube into the rock borehole and make the top of the first storage tube protrude from the borehole opening;

[0017] S2. Inject liquid oxygen-nitrogen mixture into the energy storage tube through the injection pipe. The mixture enters the bottom of the absorbent through the input pipe. At the same time, open the shut-off valve on the exhaust pipe to allow the air in the energy storage tube to be discharged through the connecting pipe and the exhaust pipe until a continuous mixture appears at the outlet of the exhaust pipe. Then close the shut-off valve.

[0018] S3. Excitation electrical energy is delivered to the ignition head through the first electrical connector. The ignition head ignites the absorbent. The heat generated by the combustion of the absorbent causes the mixture to vaporize and expand instantly, and its volume increases rapidly, producing high-pressure gas.

[0019] S4. High-pressure gas breaks through the energy storage tube and acts on the borehole wall, causing cracks in the rock and expanding them, thus achieving rock splitting.

[0020] Compared with existing technologies, the present invention provides a liquid oxygen-nitrogen composite phase change rock-fracture device and method for high-altitude and cold-climate mines. By filling the hollow area with vacuum insulation material or maintaining a vacuum state, the heat conduction from the external high-altitude and cold environment to the inside of the energy storage tube is effectively blocked, significantly reducing the evaporation loss of the liquid oxygen-nitrogen mixture. At the same time, by inserting one end of the input pipe into the bottom of the absorbent and cooperating with the shut-off valve on the exhaust pipe, the mixture is allowed to permeate upward from the bottom of the absorbent and completely expel the air in the energy storage tube. This achieves the effect of keeping the mixture in a liquid state for a long time in high-altitude and cold environments, with no air residue after injection, and stable and reliable phase change reaction.

[0021] The first storage tube is connected to the second storage tube by a threaded mounting groove at the bottom, and the power transmission head and the second power connector are electrically connected to each other. This achieves the mechanical and electrical synchronous series connection of the multi-stage energy storage tubes, thus enabling multi-stage relay excitation within a single hole during deep hole operations and ensuring that the rock fracture depth is not limited by the length of a single tube. The explosion-proof junction box, protective cover, and connecting wires effectively prevent accidental electric arcs from igniting the external environment and conduct away stray electrostatic currents, thereby achieving the effect of remote and safe excitation in high-altitude and cold mining environments. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0023] Figure 1 This is an overall structural plan view provided for an embodiment of the present invention;

[0024] Figure 2 A perspective view of the overall structure provided in an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the threaded insertion tube structure provided in an embodiment of the present invention;

[0026] Figure 4 A schematic diagram of the threaded mounting groove structure provided in an embodiment of the present invention;

[0027] Figure 5 A schematic diagram of the hollow region structure provided in an embodiment of the present invention;

[0028] Figure 6 This is a schematic diagram of the absorbent structure provided in an embodiment of the present invention.

[0029] Explanation of reference numerals in the attached figures:

[0030] 1. First storage tube; 2. Partition plate; 3. Energy storage tube; 4. Fixing ring; 5. Hollow area; 6. Absorbent; 7. Injection tube; 8. First one-way valve; 9. Input tube; 10. Exhaust tube; 11. Connecting tube; 12. Shut-off valve; 13. First electrical connector; 14. Explosion-proof junction box; 15. Wire; 16. Ignition head; 17. Power transmission head; 18. Threaded mounting groove; 19. Threaded insertion tube; 20. Protective cover; 21. Connecting wire; 22. Second storage tube; 23. Second electrical connector. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0032] As attached Figure 1 To be continued Figure 6 As shown:

[0033] Example 1:

[0034] This invention provides a liquid oxygen-nitrogen composite phase transformation rock-fracture device for high-altitude cold mines, including a first storage tube 1, a partition plate 2 installed on the inner wall of the first storage tube 1, an energy storage tube 3 arranged on one side of the inner wall of the first storage tube 1 located on the partition plate 2, and fixing rings 4 installed on both sides of the surface of the energy storage tube 3, and the fixing rings 4 are installed on the inner wall of the first storage tube 1, forming a hollow area 5 between the first storage tube 1 and the energy storage tube 3;

[0035] The inner wall of the energy storage tube 3 is filled with absorbent 6. An injection tube 7 is installed at the top of the first storage tube 1. A first one-way valve 8 is installed on the inner wall of the injection tube 7. An input tube 9 is installed at the bottom of the injection tube 7, and one end of the input tube 9 is inserted into the absorbent 6 in the energy storage tube 3. An exhaust tube 10 is installed at the top of the first storage tube 1. A connecting tube 11 is installed at the bottom of the exhaust tube 10, and one end of the connecting tube 11 is inserted into the inner wall of the energy storage tube 3, located above the absorbent 6. A shut-off valve 12 is installed on the inner wall of the exhaust tube 10. The materials of the first storage tube 1 and the energy storage tube 3 are modified nylon, high-density polyethylene, or thin-walled stainless steel. The notched impact strength of the modified nylon at -40℃ is ≥10kJ / m², the wall thickness of the thin-walled stainless steel is 0.5~1.5mm, and the absorbent 6 is one or more combinations of multi-layer roll paper, wood chip pressed rod, or porous foam metal impregnated with combustible resin, with a porosity of 40%~70% and a moisture content ≤1%.

[0036] In use, the first storage tube 1 serves as the outer protective shell of the entire rock-fracturing device. It is made of a low-temperature resistant and high-impact-strength material. Its internal space is used to accommodate the energy storage tube 3 and form an insulated hollow area 5. It also provides a mounting base for the injection tube 7, the exhaust tube 10, and the electrical connection components. The partition plate 2 is installed on the inner wall of the first storage tube 1 to divide the inner cavity of the first storage tube 1 into different functional areas, either vertically or horizontally, to prevent the absorbent 6 or the mixture from accidentally entering the non-working area. It also provides axial positioning support for the energy storage tube 3. The energy storage tube 3 is located inside the first storage tube 1 and on one side of the partition plate 2. It serves as the core reaction vessel that directly withstands the high pressure of the phase change. Its interior is filled with absorbent 6, which undergoes controlled rupture after activation, releasing the expanding gas. Pressure is transmitted to the borehole wall; the fixing ring 4 is installed on both sides of the surface of the energy storage tube 3 and fixedly connected to the inner wall of the first storage tube 1, used to coaxially suspend and fix the energy storage tube 3 inside the first storage tube 1, ensuring that a uniform hollow area 5 is formed between the two, and bearing the vibration and impact loads during the filling and transportation process; the hollow area 5 is the annular gap between the first storage tube 1 and the energy storage tube 3, which can be filled with vacuum insulation material, aerogel or kept in a vacuum state, used to block the heat exchange between the external high-altitude environment and the internal mixture, significantly reducing the evaporation loss of the liquid oxygen-nitrogen mixture, and ensuring that the cryogenic liquid remains liquid for a long time after filling; the absorbent 6 is filled into the inner wall of the energy storage tube 3, using multi-layer roll paper, wood chip pressed rod or porous foam metal. Made of porous combustible materials such as impregnated combustible resin, with a porosity of 40%–70% and a water content ≤1%, its function is to rapidly absorb and store the liquid oxygen-nitrogen mixture input through the injection pipe 7, and stably burn after being ignited by the igniter head 16, generating a large amount of heat to promote the instantaneous vaporization of the mixture. The injection pipe 7 is installed at the top of the first storage pipe 1, serving as the connection interface for the external mixture filling gun, used to deliver a predetermined proportion of liquid oxygen-nitrogen mixture into the device. The first one-way valve 8 is installed on the inner wall of the injection pipe 7, allowing the mixture to flow in one direction while preventing internal gas or liquid from being ejected in reverse. It automatically closes after filling to ensure the airtightness of the energy storage pipe 3. The input pipe 9 is installed at the bottom of the injection pipe 7, with one end inserted into the energy storage pipe 3. Inside the absorbent 6, typically extending to the bottom, the mixture is used to directly deliver the liquid to the deepest part of the absorbent 6, achieving reverse filling from bottom to top, thereby completely expelling the air from the energy storage tube 3; the exhaust pipe 10 is installed at the top of the first storage tube 1, serving as a channel for gas discharge during the filling process; the connecting pipe 11 is installed at the bottom of the exhaust pipe 10, with one end inserted into the inner wall of the energy storage tube 3 and located above the absorbent 6, used to guide the air in the top space of the energy storage tube 3 to the exhaust pipe 10; the shut-off valve 12 is installed on the inner wall of the exhaust pipe 10, which can be opened manually or automatically during filling to discharge air, and the valve is closed when a continuous mixture appears at the outlet of the exhaust pipe 10 to prevent the mixture from leaking out and to keep the inside of the energy storage tube 3 sealed.The above structures work together to achieve safe injection, sealed storage, thermal insulation, and controllable phase change in liquid oxygen-nitrogen mixtures in frigid environments, ultimately enabling efficient rock crushing through gasification expansion pressure.

[0037] Example 2:

[0038] This embodiment is basically the same as the previous embodiment, except that a first electrical connector 13 is installed at the top of the first storage tube 1, an explosion-proof junction box 14 is installed at the bottom of the first electrical connector 13, a wire 15 is electrically connected to the bottom of the explosion-proof junction box 14, an ignition head 16 is electrically connected to the bottom of the wire 15, and the ignition head 16 is located on the inner bottom wall of the absorbent 6. A power supply head 17 is electrically connected to the bottom of the wire 15, and a threaded mounting groove 18 is provided at the bottom of the first storage tube 1. A threaded connector 19 is installed at the top of the first storage tube 1, which is sleeved on the outside of the power transmission head 17. The threaded connector 19 is sleeved on the outside of the injection tube 7 and the exhaust tube 10. A protective cover 20 is threaded on the surface of the threaded connector 19. A power wire 21 is electrically connected to the top of the protective cover 20. A second storage tube 22 is threaded on the bottom of the first storage tube 1. A second power connector 23 is provided at the top of the second storage tube 22. The second power connector 23 is electrically connected to the power transmission head 17.

[0039] In use, the first connector 13 is installed at the top of the first storage tube 1, serving as the electrical interface between the external excitation power supply and the internal ignition circuit. It is sealed with a low-temperature resistant, high-insulation material to ensure stable transmission of excitation energy in cold and humid environments. The explosion-proof junction box 14 is installed at the bottom of the first connector 13, accommodating and protecting the connection point between the wire 15 and the ignition head 16. Its housing has explosion-proof functionality, preventing accidental arcing or high temperatures from igniting external flammable gases, while also avoiding damage to the wiring structure from internal pressure surges. The wire 15 is electrically connected to the bottom of the explosion-proof junction box 14, with its end electrically connected to the ignition head 16. The copper core wire is insulated with low-temperature resistant silicone rubber, maintaining flexibility and conductivity even at -60℃, and is used to transmit the excitation energy to the ignition head 16 without loss. The ignition head 16 is located on the inner bottom wall of the absorbent 6, and contains a bridge wire and igniting powder. When energized, it instantly generates a high-temperature flame to ignite the absorbent 6, and is the key actuator for initiating the phase change reaction. The power transmission head 17 is electrically connected to the bottom end of the conductor 15, located at the bottom of the first storage tube 1, and is used to transmit the excitation signal to the lower-level energy storage tube or the second storage tube 22 when multiple sections are connected in series, ensuring the circuit continuity during long-hole or multi-hole relay excitation. The threaded mounting groove 18 is opened at the bottom end of the first storage tube 1. A threaded connector 17 is fitted onto the surface of the power transmission head 17 and fixed to the bottom of the first storage tube 1 via a threaded connection. This provides both mechanical positioning and electrical insulation, facilitating quick docking with downstream devices. A threaded connector 19 is installed at the top of the first storage tube 1 and fitted onto the surfaces of the injection tube 7 and the exhaust tube 10. This serves to centrally fix and protect these two thin tubes, while also providing a threaded connection base for the protective cover 20 to prevent damage to the pipelines during transportation or filling. The protective cover 20 is threaded onto the surface of the threaded connector 19 and, in the non-excitation state, covers and seals the top of the first storage tube 1 to prevent dust and moisture from entering. Its top is electrically connected to... A connecting wire 21 is included; one end of the connecting wire 21 is connected to the protective cover 20, and the other end is used to connect to the field grounding system to promptly conduct away static electricity and stray current, preventing accidental excitation; the second storage tube 22 is threaded to the bottom end of the first storage tube 1, serving as an extension unit, allowing multiple energy storage tubes to be connected in series during deep-hole operations, increasing the single-hole charge length and enabling continuous rock fracturing at greater depths; the second connector 23 is located at the top of the second storage tube 22 and is electrically connected to the transmission head 17, used to receive the excitation signal from the upper-level first storage tube 1 and transmit it to the ignition element inside the second storage tube 22, ensuring that the multi-stage series device is reliably ignited simultaneously. The above structures work together to achieve the safe introduction and reliable transmission of excitation energy, the mechanical and electrical series connection of the multi-stage energy storage tubes, electrostatic protection, and the sealing protection of the top interface, thereby ensuring that the rock fracturing device can be remotely, controllably, and relayed from multiple points in a high-altitude, cold mining environment, effectively completing deep-hole or long-distance rock fracturing operations.

[0040] Example 3:

[0041] A liquid oxygen-nitrogen composite phase transformation fracturing method for high-altitude and cold-climate mines includes the following steps:

[0042] S1. Insert the energy storage tube 3 into the rock borehole and make the top of the first storage tube 1 protrude from the borehole opening.

[0043] S2. Inject liquid oxygen-nitrogen mixture into energy storage tube 3 through injection pipe 7. The mixture enters the bottom of absorbent 6 through input pipe 9. At the same time, open shut-off valve 12 on exhaust pipe 10 to allow air in energy storage tube 3 to be discharged through connecting pipe 11 and exhaust pipe 10 until continuous mixture appears at the outlet of exhaust pipe 10. Then close shut-off valve 12.

[0044] S3. Excitation energy is delivered to the ignition head 16 through the first electrical connector 13. The ignition head 16 ignites the absorbent 6. The heat generated by the combustion of the absorbent 6 causes the mixture to vaporize and expand instantly, and its volume increases rapidly, producing high-pressure gas.

[0045] S4. High-pressure gas breaks through the energy storage tube 3 and acts on the borehole wall, causing cracks in the rock and expanding them, thus achieving rock splitting.

[0046] This also includes the following follow-up content:

[0047] S5. Preparation of the mixture: Before injecting the mixture into the energy storage tube 3, liquid oxygen and liquid nitrogen are mixed in an external mixing tank at a volume ratio of 30% to 50%: 70% to 50%, the mixing temperature is controlled to be no lower than -190°C, and the mixture is allowed to stand for 1 to 2 minutes to ensure uniform mixing, thus obtaining a liquid oxygen-nitrogen mixture; the mixing tank is equipped with a gas phase port, and during filling, liquid oxygen is introduced first, followed by liquid nitrogen, and the gas phase port is kept open to release the evaporated gas.

[0048] S6. Pretreatment before injection: Before step S2, first purge the inside of the energy storage tube 3, as well as the injection tube 7, input tube 9, exhaust tube 10, and connecting tube 11 with dry nitrogen to replace the air in the tubes and remove moisture to prevent freezing and blockage at low temperatures; then preheat the exposed part of the top of the first storage tube 1 by heating it to above 0°C using an electric heating tape or hot air gun for 3 to 5 minutes to ensure that the one-way valves in the injection tube 7 and exhaust tube 10 operate flexibly.

[0049] S7. Multi-hole series excitation: When the depth of the rock borehole is greater than the length of a single first storage tube 1, multiple first storage tubes 1 are connected to the second storage tube 22 in sequence by threaded mounting groove 18, and the power transmission head 17 and the second power connector 23 are electrically connected in sequence. In step S3, the excitation energy is transmitted to the ignition head 16 of each stage through the first power connector 13, the explosion-proof junction box 14, the wire 15 and the power transmission head 17, so as to realize the synchronous or micro-delay excitation of all series energy storage tubes 3.

[0050] S8. Insulation measures for cold environments: After the borehole is installed in step S1, cover the borehole with an insulation cover or fill it with polyurethane foam to prevent cold air from blowing directly onto the top of the first storage tube 1; at the same time, wrap the outer wall of the injection tube 7 and the exhaust tube 10 with a self-limiting electric heating tape to maintain the pipeline temperature above -10℃ and prevent the mixture from vaporizing prematurely due to the pipeline being too cold during the injection process.

[0051] S9. Safety Excitation Control: Before step S3, reliably ground the protective cover 20 and the first storage tube 1 through the connecting wire 21, measure the circuit resistance value, and confirm that the resistance of the ignition head 16 is within the range of 2Ω to 4Ω and there is no short circuit or open circuit; then all personnel evacuate to more than 30m away from the blast hole, and use a wired remote control exciter to deliver excitation energy to the first connecting head 13. The excitation voltage is 200V to 400V, the energy storage capacitor capacity is 2000μF to 10000μF, and the single excitation energy is not less than 50J.

[0052] S10. Rock-breaking effect inspection and supplementary activation: After completing step S4, wait 1 to 2 minutes to allow the pressure inside the hole to be completely released, and then observe the distribution and size of cracks on the rock surface. If there are areas that are not completely broken, drill holes in these areas and repeat steps S1 to S4 for secondary rock-breaking, or adjust the volume ratio of liquid oxygen in the mixture to increase by 5% to 10% to improve the rock-breaking energy.

[0053] Application example:

[0054] In the high-altitude, frigid mining areas of western my country, winter temperatures often drop below -30 degrees Celsius, with permafrost and hard rock coexisting. Traditional explosive blasting suffers from reduced explosive strength and increased misfire rate due to low temperatures, and blasting vibrations easily trigger slope collapses and permafrost damage. Furthermore, the transportation and storage of explosives in high-altitude, frigid mountainous areas pose significant safety hazards. Mechanical rock-breaking methods, such as hydraulic breakers and impact drills, experience increased hydraulic oil viscosity and reduced drill bit toughness at extremely low temperatures, leading to a sharp drop in construction efficiency and frequent equipment failures. To address these problems, this technical solution provides a liquid oxygen-nitrogen composite phase change rock-breaking device and method for high-altitude, frigid mines. It utilizes the instantaneous vaporization and expansion of a liquid oxygen and liquid nitrogen mixture within a sealed energy storage tube 3 to generate high pressure, thereby breaking the rock through a physical phase change process.

[0055] First, based on the geological data and bench design of the mining area, a down-the-hole drill was used to drill boreholes in the rock mass to be fractured, with a diameter matching the outer diameter of the first storage pipe 1. The depth of the boreholes was determined according to the designed bench height. After drilling, high-pressure air was used to blow away rock powder and accumulated water from the boreholes to prevent residual moisture from freezing at low temperatures and affecting subsequent operations. The work team transported the pre-assembled rock-fracture device to the site. This device includes the first storage pipe 1, partition plate 2, energy storage pipe 3, fixing ring 4, hollow area 5, absorbent 6, injection pipe 7, first one-way valve 8, input pipe 9, exhaust pipe 10, connecting pipe 11, and shut-off valve 12. The absorbent 6 is made of multi-layer rolled paper with a porosity of approximately 50%, and has been pre-filled inside the energy storage pipe 3. The operators lifted the entire device and slowly lowered the energy storage pipe 3 and the first storage pipe 1 into the borehole until the top of the first storage pipe 1 protruded about 20 centimeters from the borehole opening, ensuring space for subsequent grouting and wiring operations. At this time, the energy storage tube 3 is coaxially fixed inside the first storage tube 1 by the fixing ring 4, and the vacuum insulation material filled in the hollow area 5 begins to play the role of blocking the external cold air and preventing the internal mixture from evaporating too quickly.

[0056] Next, a mobile mixing tank was used on-site to prepare a liquid oxygen-nitrogen mixture. The mixing tank has independent liquid oxygen and liquid nitrogen inlets, and a gas phase port for pressure relief. The operator first opened the gas phase port valve of the mixing tank, then injected the cryogenic liquid into the tank in the order of first filling with liquid oxygen, then liquid nitrogen. Once the liquid level reached the target volume, the inlet valve was closed, and the mixture was allowed to stand for about two minutes to homogenize. Subsequently, the quick connector of the injection gun was connected to the injection pipe 7 at the top of the first storage pipe 1, and the exhaust pipe 10 was led to a safe area via a flexible hose. The operator opened the shut-off valve 12 on the exhaust pipe 10, and then slowly opened the outlet valve of the mixing tank. The mixture was then transported to the energy storage pipe 3 through the injection pipe 7, the first one-way valve 8, and the input pipe 9. Since one end of the input pipe 9 was inserted into the bottom of the absorbent 6, the mixture permeated upwards from the bottom of the absorbent 6. Simultaneously, the original air in the energy storage pipe 3 was pushed upwards by the mixture and discharged through the connecting pipe 11, the exhaust pipe 10, and the shut-off valve 12. When the operator observes a continuous, bubble-free mixture at the outlet of exhaust pipe 10, it indicates that the air inside the energy storage tube 3 has been completely purged. The operator immediately closes the shut-off valve 12 and disconnects the injection gun. At this time, the first one-way valve 8 automatically closes the injection pipe 7 to prevent backflow or leakage of the mixture. Throughout the injection process, the insulation layer of the hollow zone 5 effectively delays the conduction of external low temperature to the energy storage tube 3, and the mixture remains liquid without significant vaporization.

[0057] After the filling is completed, the operator connects the first connector 13 to the external ignition cable. The first connector 13 is installed at the top of the first storage tube 1, below which are arranged an explosion-proof junction box 14, a wire 15, and an ignition head 16. The ignition head 16 is located on the inner bottom wall of the absorbent 6, and the power supply head 17 is located at the bottom of the wire 15 for multi-stage series connection. In this application example, the borehole depth is relatively large, requiring two sets of devices to be connected in series. Therefore, the threaded mounting groove 18 at the bottom of the first storage tube 1 is tightened with the thread at the top of the second storage tube 22, while ensuring that the power supply head 17 and the second connector 23 at the top of the second storage tube 22 are electrically connected to each other, realizing the series connection of the two-stage ignition circuit. Afterwards, the operator tightens the protective cover 20 on the surface of the threaded plug tube 19, and the connecting wire 21 electrically connected to the top of the protective cover 20 is connected to the on-site grounding grid to promptly conduct away static electricity and stray current. All personnel are evacuated to a safe distance to the side of the borehole. The igniter is operated by wired remote control, and the operator presses the ignition button behind the protective cover.

[0058] The ignition energy is simultaneously transmitted to the first-stage ignition head 16 via the first connector 13, the explosion-proof junction box 14, and the wire 15, and then to the second-stage ignition head 16 via the transmission head 17 and the second connector 23. The ignition head 16 instantly generates a high-temperature flame, igniting the absorbent 6. The absorbent 6 burns violently within the energy storage tube 3. The large amount of heat generated causes the temperature of the liquid oxygen-nitrogen mixture adsorbed in the pores of the absorbent 6 to rise sharply, instantly exceeding its boiling point. The mixture changes from a liquid to a gaseous state, expanding in volume hundreds of times. Due to the thin-walled structure of the energy storage tube 3 and the sudden increase in internal pressure, the energy storage tube 3 fractures uniformly along its axial direction. The high-pressure gas breaks through the energy storage tube 3 and passes through the hollow region 5 and the weak points of the sidewall of the first storage tube 1, directly acting on the borehole wall. Under the internal high pressure, the rock in the borehole wall develops radial cracks, which rapidly expand and penetrate, forming a uniformly sized fragmented rock mass.

[0059] Working principle: During operation, the entire rock-splitting device is first placed into a pre-drilled rock borehole. The first storage tube 1 serves as the outer protective shell, and its internal partition plate 2 divides the inner cavity of the first storage tube 1 into different functional areas to prevent the absorbent 6 or the mixture from accidentally entering the non-working area, while providing axial positioning support for the energy storage tube 3. The energy storage tube 3 is coaxially suspended and fixed to the inner wall of the first storage tube 1 by fixing rings 4 on both sides of its surface, so that a hollow area 5 is formed between the first storage tube 1 and the energy storage tube 3. The hollow area 5 is filled with vacuum insulation material or kept in a vacuum state to block the heat conduction from the external high and low temperature environment to the inside of the energy storage tube 3, thereby significantly reducing the evaporation loss of the liquid oxygen-nitrogen mixture. The inside of the energy storage tube 3 is filled with absorbent 6 with a porosity of 40% to 70% and a water content of ≤1%. The absorbent 6 is made of porous combustible materials such as multi-layer roll paper, wood chip pressed rods, or porous foam metal impregnated with combustible resin, which can quickly absorb and store the liquid oxygen-nitrogen mixture injected from the outside. When filling the mixture, the output interface of the external mixing tank is connected to the injection pipe 7 at the top of the first storage pipe 1. The mixture enters the input pipe 9 through the first one-way valve 8 on the inner wall of the injection pipe 7 (this valve allows the mixture to flow in one direction and prevents it from spraying out in the opposite direction). Since one end of the input pipe 9 is inserted into the bottom of the absorbent 6, the mixture directly soaks upward from the deepest part of the absorbent 6. At the same time, the operator opens the shut-off valve 12 installed on the inner wall of the exhaust pipe 10, so that the air in the energy storage pipe 3 is pushed upward and discharged out of the pipe in sequence through the connecting pipe 11 (which is inserted into the inner wall of the energy storage pipe 3 and is located above the absorbent 6), the exhaust pipe 10 and the shut-off valve 12. When the mixture appears continuously at the outlet of the exhaust pipe 10, it indicates that the air inside the energy storage pipe 3 has been exhausted and the absorbent 6 has been completely soaked. At this time, the shut-off valve 12 is closed and the first one-way valve 8 is also automatically closed to ensure that the energy storage pipe 3 is in a sealed state. During the induction of rock fracturing, the operator transmits the ignition energy to the explosion-proof junction box 14 through the first electrical connector 13 (installed at the top of the first storage tube 1, serving as the electrical interface for the external ignition power supply). The explosion-proof junction box 14 houses and protects the connection nodes of the wire 15, preventing the electric arc from igniting the external environment. The ignition energy is transmitted through the wire 15 (using low-temperature resistant silicone rubber insulated copper core wire) to the ignition head 16 located on the inner bottom wall of the absorbent 6. The bridge wire inside the ignition head 16 heats up instantly and ignites the igniting powder, generating a high-temperature flame, which in turn ignites the absorbent 6. The absorbent 6 burns violently inside the energy storage tube 3. The large amount of heat generated by the combustion causes the temperature of the liquid oxygen-nitrogen mixture adsorbed in the pores of the absorbent 6 to rise sharply and vaporize instantly, expanding its volume hundreds of times to form a high-pressure gas. Due to the thin-walled structure of the energy storage tube 3 and the sudden increase in internal pressure, the energy storage tube 3 undergoes uniform rupture along its axial direction. The high-pressure gas breaks through the energy storage tube 3, passes through the hollow area 5, and acts on the borehole wall, causing cracks in the rock to form and propagate, thus achieving rock fracturing.When multiple stages of devices need to be connected in series to deepen the rock fracture depth, the threaded mounting groove 18 at the bottom of the first storage tube 1 can be threadedly connected to the second storage tube 22. At the same time, the power transmission head 17 (electrically connected to the bottom of the conductor 15) and the second power connector 23 at the top of the second storage tube 22 are electrically connected to each other, realizing the multi-stage relay transmission of excitation energy. In addition, the threaded insertion pipe 19 at the top of the first storage tube 1 is sleeved on the surface of the injection pipe 7 and the exhaust pipe 10 to centrally fix and protect these two thin tubes. The protective cover 20 threaded on its surface covers and seals the top in the non-excitation state to prevent dust and moisture from entering. The grounding wire 21 electrically connected to the top of the protective cover 20 is used to connect to the field grounding system to conduct away static electricity and stray current in time to avoid accidental excitation. The above components work together to realize the safe injection, heat insulation, sealed storage, and remotely controllable physical phase change excitation of liquid oxygen-nitrogen mixture in a cold environment, and finally efficiently crush the rock through gasification expansion pressure.

[0060] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A liquid oxygen-nitrogen composite phase transformation rock fracturing device for high-altitude cold mines, comprising a first storage tube (1), characterized in that, A partition plate (2) is installed on the inner wall of the first storage tube (1). An energy storage tube (3) is provided on one side of the partition plate (2) on the inner wall of the first storage tube (1). Fixing rings (4) are installed on both sides of the surface of the energy storage tube (3). The fixing rings (4) are installed on the inner wall of the first storage tube (1). A hollow area (5) is formed between the first storage tube (1) and the energy storage tube (3). The inner wall of the energy storage tube (3) is filled with absorbent (6). An injection tube (7) is installed at the top of the first storage tube (1). A first one-way valve (8) is installed on the inner wall of the injection tube (7). An input tube (9) is installed at the bottom of the injection tube (7), and one end of the input tube (9) is inserted into the absorbent (6) in the energy storage tube (3). An exhaust tube (10) is installed at the top of the first storage tube (1). A connecting tube (11) is installed at the bottom of the exhaust tube (10), and one end of the connecting tube (11) is inserted into the inner wall of the energy storage tube (3) above the absorbent (6). A shut-off valve (12) is installed on the inner wall of the exhaust tube (10).

2. The liquid oxygen-nitrogen composite phase transformation rock fracturing device for high-altitude and cold-climate mines according to claim 1, characterized in that, The first storage tube (1) is equipped with a first electrical connector (13) at its top end, and an explosion-proof junction box (14) is installed at the bottom end of the first electrical connector (13). The bottom end of the explosion-proof junction box (14) is electrically connected to a wire (15). The bottom end of the wire (15) is electrically connected to an ignition head (16), and the ignition head (16) is located on the inner bottom wall of the absorbent (6). The bottom end of the wire (15) is electrically connected to a power transmission head (17).

3. The liquid oxygen-nitrogen composite phase transformation rock fracturing device for high-altitude cold mines according to claim 1, characterized in that, The bottom end of the first storage tube (1) is provided with a threaded mounting groove (18), and the threaded mounting groove (18) is sleeved on the outside of the power transmission head (17).

4. The liquid oxygen-nitrogen composite phase transformation rock fracturing device for high-altitude and cold-climate mines according to claim 1, characterized in that, The top end of the first storage tube (1) is fitted with a threaded connector (19), and the threaded connector (19) is sleeved on the outside of the injection tube (7) and the exhaust tube (10).

5. The liquid oxygen-nitrogen composite phase transformation rock fracturing device for high-altitude and cold-climate mines according to claim 4, characterized in that, The threaded connector (19) is threadedly connected to a protective cover (20), and the top of the protective cover (20) is electrically connected to a grounding wire (21).

6. The liquid oxygen-nitrogen composite phase transformation rock fracturing device for high-altitude and cold-climate mines according to claim 1, characterized in that, The bottom end of the first storage tube (1) is threadedly connected to a second storage tube (22).

7. The liquid oxygen-nitrogen composite phase transformation rock fracturing device for high-altitude and cold-climate mines according to claim 6, characterized in that, The second storage tube (22) is provided with a second electrical connector (23) at its top end, and the second electrical connector (23) is electrically connected to the power supply head (17).

8. The liquid oxygen-nitrogen composite phase transformation rock fracturing device for high-altitude and cold-climate mines according to claim 1, characterized in that, The first storage tube (1) and the energy storage tube (3) are made of modified nylon, high-density polyethylene or thin-walled stainless steel; the modified nylon has a notched impact strength of ≥10kJ / m² at -40℃, and the thin-walled stainless steel has a wall thickness of 0.5~1.5mm.

9. The liquid oxygen-nitrogen composite phase transformation rock fracturing device for high-altitude cold mines according to claim 1, characterized in that, The absorbent (6) is one or more of the following: multi-layer paper roll, wood chip pressed rod, or porous foam metal impregnated with combustible resin, with a porosity of 40% to 70% and a moisture content of ≤1%.

10. A method for fracturing rocks using liquid oxygen-nitrogen composite phase transformation in high-altitude and cold-climate mines, applicable to the liquid oxygen-nitrogen composite phase transformation fracturing rock device for high-altitude and cold-climate mines as described in any one of claims 1 to 9, characterized in that... Includes the following steps: S1. Insert the energy storage tube (3) into the rock borehole and make the top of the first storage tube (1) protrude from the borehole. S2. Inject liquid oxygen-nitrogen mixture into the energy storage tube (3) through the injection pipe (7). The mixture enters the bottom of the absorbent (6) through the input pipe (9). At the same time, open the shut-off valve (12) on the exhaust pipe (10) so that the air in the energy storage tube (3) is discharged through the connecting pipe (11) and the exhaust pipe (10) until a continuous mixture appears at the outlet of the exhaust pipe (10). Then close the shut-off valve (12). S3. Excitation energy is delivered to the ignition head (16) through the first electrical connector (13). The ignition head (16) ignites the absorbent (6). The heat generated by the combustion of the absorbent (6) causes the mixture to vaporize and expand instantly, and its volume increases sharply, producing high-pressure gas. S4. High-pressure gas breaks through the energy storage tube (3) and acts on the borehole wall, causing cracks in the rock and expanding them to achieve rock splitting.

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