A device and method for pre-splitting ore body based on vapor explosion principle

Abstract

The present application relates to the technical field of mine exploitation equipment, and specifically discloses a kind of ore body pre-splitting device and method based on steam explosion principle.A kind of ore body pre-splitting device based on steam explosion principle, comprising: outer liquid chamber, inner reaction chamber, heating device, solid heat source located in the inner reaction chamber, pressure relief port, blasting device, sensor assembly, electronic controller, the signal input end of electronic controller is connected with the signal output end of sensor assembly, the signal output end of electronic controller is connected with the control end of heating device.The present application converts steam explosion energy into controllable cracking force, realizes the controllable explosion direction, the pressure peak value 5-30MPa is adjustable, solves the problem of traditional blasting vibration, hydraulic fracturing sealing difficulty, has the advantages of green safety, energy utilization rate>85%.

Description

Technical Field

[0001] This invention relates to the technical field of ore body blasting pre-splitting, specifically to an ore body pre-splitting device and method based on the principle of steam explosion. Background Technology

[0002] Bauxite, iron ore, copper ore, and other mineral resources play a vital role in modern industrial systems. As societal demand for mineral resources grows, resources in shallow and easily exploitable areas are gradually being depleted, and mineral resource development is increasingly shifting towards underground ore bodies that are buried at greater depths and have more complex geological conditions.

[0003] Because these types of ore bodies are typically high in strength and integrity, room-and-pillar blasting is commonly used for mining. However, this method is not only inefficient but also results in a large amount of pillars, significantly reducing resource recovery. To improve recovery rates, fully mechanized mining has been applied in some mines, but for hard ore bodies, fully mechanized mining equipment faces difficulties in cutting, slow mining progress, severe tool wear, and poor economic benefits. Therefore, it is necessary to perform efficient pre-fracture treatment on the ore body before mining to improve its mineability and create favorable conditions for subsequent mechanized continuous mining.

[0004] Currently, common methods for pre-fracture of ore bodies include traditional technologies such as explosive blasting, hydraulic fracturing, and static fracturing agent methods. Explosive blasting generates shock waves to fracture the rock mass through blasting, but the use of explosives poses significant safety hazards, as blast vibrations can easily damage the stability of the surrounding rock, and the sealing process is complex. Hydraulic fracturing uses high-pressure water to fracture the ore body, but faces technical bottlenecks such as easy sealing failure in fractured ore bodies, high water consumption per borehole making it difficult to apply in water-scarce mining areas, and uncontrollable fracture propagation direction. Static fracturing agent methods generate expansion stress through expansive agents to fracture the ore body, but have prominent problems such as long reaction time and insufficient expansion stress.

[0005] Therefore, there is an urgent need for a new ore body pre-fracture technology that is energy-controllable, safe and efficient, can achieve controllable fractures (controllable explosion direction), and is applicable to different mines, so as to improve the crushing efficiency and resource recovery rate of high-strength ore bodies and meet the needs of green mine construction. Summary of the Invention

[0006] The purpose of this invention is to provide a pre-splitting device and method for ore bodies based on the principle of steam explosion, so as to solve the problems of inaccurate energy release, inability to control the direction of fractures and limited applicability in the prior art. Thus, while ensuring the pre-splitting effect, it also has the advantages of safety, high efficiency and environmental protection.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: a pre-splitting device for ore bodies based on the principle of steam explosion, comprising:

[0008] The outer liquid chamber has an opening at the top, with an upper sealing cover installed at the opening, and is filled with liquid working fluid.

[0009] The inner reaction chamber is located inside the outer liquid chamber. The top of the inner reaction chamber has an opening that is sealed and connected to the bottom of the upper sealing cover. The outer wall of the inner reaction chamber does not contact the inner wall of the outer liquid chamber.

[0010] A heating device is connected to the upper sealing cover and extends into the inner reaction chamber.

[0011] A solid heat source, located inside the inner reaction chamber, is heated by the heating device to form a high-temperature molten substance capable of breaking through the inner reaction chamber;

[0012] Pressure relief ports, at least one pair, are symmetrically located on the side wall of the outer liquid chamber, forming a tubular structure extending outward from the opening on the side wall of the outer liquid chamber;

[0013] The blasting device has one end connected to the outlet end of the pressure relief port;

[0014] The sensor assembly has its probe extending into the outer liquid chamber to measure the temperature and pressure of the liquid working medium inside the outer liquid chamber;

[0015] The electronic controller has its signal input terminal connected to the signal output terminal of the sensor assembly, and its signal output terminal connected to the control terminal of the heating device.

[0016] Furthermore, the other end of the blasting device is connected to a shaped charge shield; the shaped charge shield has a tapered cylindrical structure, and the shaped charge shield is connected to the other end of the blasting device through the large-diameter end, while the small-diameter end serves as the shaped charge port.

[0017] Furthermore, the blasting device includes a rupture disc, a clamp, and a flange. One end of the clamp is connected to the outlet end of the pressure relief port, the rupture disc is clamped inside the clamp, and the flange is connected between the other end of the clamp and the large-diameter end of the shaped charge.

[0018] Furthermore, both the outer liquid chamber and the inner reaction chamber are cylindrical structures with open tops. There are two pairs of pressure relief ports, arranged vertically on the sidewall of the outer liquid chamber. The axes of the two pressure relief ports on the same side intersect with the same generatrix on the sidewall of the outer liquid chamber. The outer liquid chamber can be a single-piece or split structure, made of a metallic material capable of withstanding the high temperature and pressure generated by a steam explosion. When a split structure is used, the outer liquid chamber has a three-layer composite structure: the inner lining is a molybdenum-titanium-zirconium alloy, directly contacting molten metal at 3500℃; the middle pressure-bearing layer is a nickel-based alloy; and the outer protective layer is a carbon fiber composite material.

[0019] Furthermore, the inner reaction chamber is made of copper (forming a copper shell), and its inner wall is coated with a zirconium oxide coating. This zirconium oxide coating reduces the copper shell's melt-through temperature from 1085°C to 820°C. The bottom plate or sidewalls of the inner reaction chamber are locally weakened zones, with the wall thickness of these weakened zones being less than that of the non-weakened zones. These weakened zones are pre-marked areas on the copper shell, specifically a honeycomb structure. The electrode posts of the heating device are connected to the upper sealing cap and installed within the inner reaction chamber.

[0020] Furthermore, the sensor unit includes a temperature sensor and a pressure sensor; both the temperature sensor and the pressure sensor are installed inside the upper sealing cover, and the probe ends extend into the outer liquid chamber.

[0021] Furthermore, the solid heat source is aluminothermic agent; the liquid working fluid is deionized water or a mixed solution of water and ethanol.

[0022] The electronic controller connects to and controls the heating device, temperature sensor, and pressure sensor, forming a closed-loop control system. The electronic controller monitors and processes the signals from the temperature and pressure sensors. When the monitored value exceeds a preset safety threshold, the electronic controller automatically reduces the heating power or cuts off the heating power, triggering a safety protection mechanism. When the monitored value is below a preset reaction threshold, the electronic controller attempts to increase the heating power; if this fails to meet expectations, it issues an operational anomaly signal, achieving precise control and safety protection of the energy release process.

[0023] An electronic controller controls the heating device, which is connected to a high-melting-point ignition wire (such as a tungsten wire). When the ignition wire continues to heat up to the ignition point of the solid heat source, it triggers a combustion reaction. The solid heat source can be selected from thermite or other metal redox systems that can react under closed conditions. The thermite reaction releases a large amount of heat and generates molten material. Fe and Al 2 O 3.

[0024] The inner reaction chamber encapsulates a solid heat source, and its chamber wall has a pre-set energy release weakening zone; the outer liquid chamber surrounds the inner reaction chamber and contains the liquid working fluid, serving as the reaction site for vapor explosion. The upper sealing cover achieves overall sealing and isolation between the inner and outer chambers.

[0025] Symmetrically arranged pressure relief ports are used to release the high-temperature and high-pressure liquid generated by the steam explosion. A rupture disc is installed outside the pressure relief port, located at the junction of the pressure relief port and the energy-concentrating hood. The rupture disc is fixed by a clamp and is replaceable. The rupture disc can handle various situations. The steam explosion power generated varies when the thermite ratio is different. The ability of the device to pre-fracture the ore body can be changed simply by replacing the rupture disc. It is suitable for different structures of different ore bodies, has wide applicability, and is convenient and quick.

[0026] The condenser shroud is connected to the outer end of the flange and is located at the outermost end of the entire container. High-temperature, high-pressure liquid is sprayed outward through the condenser shroud, enhancing the pre-fracture effect on the target ore body. The flange, clamp, and rupture disc are all connected by standard bolts. The direction of the high-temperature, high-pressure liquid jet is: pressure relief port → rupture disc → condenser shroud.

[0027] This invention also provides a pre-fracture method for ore bodies based on the principle of steam explosion, which is implemented using an ore body pre-fracture device based on the principle of steam explosion, and includes the following steps:

[0028] S1. Drilling Positioning: Determine the drilling location, depth, and azimuth based on the mechanical properties of the target ore body and the pre-splitting requirements;

[0029] S2. Device loading: A solid heat source is loaded and encapsulated in the inner reaction chamber, a liquid working medium is injected into the outer liquid chamber, and the inner reaction chamber and the outer liquid chamber are sealed by the upper sealing cap;

[0030] S3. Directional deployment: Place the device into the borehole and adjust the position of the device so that the energy focusing port of the energy focusing cover faces the preset fracture propagation surface;

[0031] S4. Drill hole sealing: Cement mortar is injected into the depth of the drill hole using a cement sealing pump, and a seal is achieved after curing.

[0032] S5. Energy Trigger: The electronic controller ignites the solid heat source in the inner reaction chamber through the heating device. The high-temperature molten material generated by the solid heat source reaction quickly melts through the weakened zone of the inner reaction chamber and rushes into the liquid working medium at high speed, triggering a steam explosion. After the instantaneous high pressure generated by the explosion reaches the rated pressure of the rupture disc, the rupture disc ruptures. The high-temperature and high-pressure fluid in the outer liquid chamber is accelerated by the energy-concentrating shroud to form a high-speed jet, which directionally impacts the preset fracture propagation surface, thereby generating and expanding fractures in the ore body.

[0033] Based on the above technical solution, this invention utilizes a heating device in the inner reaction chamber, which serves as the reaction vessel, to burn a solid heat source. Simultaneously, molten metal rushes out of the inner reaction chamber at a certain speed and enters the liquid working medium. In the sealed container, the molten metal's contact with the room-temperature liquid immediately triggers a steam explosion, increasing the pressure inside the container. When the pressure exceeds the rated value of the rupture disc, the rupture disc breaks, causing the high-pressure liquid to rush into the energy-concentrating hood and further pressurize the liquid, allowing it to eject at an even faster speed, thus achieving the purpose of pre-fracture of the ore body. By using the steam explosion phenomenon, considered a hazard in industry, as the pre-fracture force, the invention achieves high energy utilization and generates significant pressure. It solves the technical problems of inaccurate energy release, inability to control fracture direction, and limited applicability in current blasting and hydraulic pre-fracture methods, making it suitable for coal mines, metal mines, and non-metal mines. Attached Figure Description

[0034] The accompanying drawings, which constitute a part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0035] Figure 1 This is an isometric front side sectional view of an ore body pre-splitting device according to an embodiment of the present invention;

[0036] Figure 2 This is a front cross-sectional view of an ore body pre-fracture device according to an embodiment of the present invention;

[0037] Figure 3 This is a top cross-sectional view of an ore body pre-fracture device according to an embodiment of the present invention;

[0038] Figure 4 This is a three-dimensional structural schematic diagram of an ore body pre-fracture device according to an embodiment of the present invention;

[0039] Figure 5 This is a flowchart of the steam explosion release process.

[0040] In the attached diagram: 1. Upper sealing cover; 2. Inner reaction chamber; 21. Heating device; 22. Solid heat source; 23. Tungsten wire; 3. Outer liquid chamber; 31. Temperature sensor; 32. Pressure sensor; 33. Liquid working fluid; 4. Explosion device; 41. Rupture disc; 42. Clamp; 43. Flange; 5. Condensing cover; 6. Socket head bolt; 7. Pressure relief port. Detailed Implementation

[0041] A pre-fracking device for ore bodies based on the principle of steam explosion, comprising:

[0042] The outer liquid chamber 3 has an opening at its top, and an upper sealing cover 1 is installed at the opening. The chamber is filled with liquid working fluid 33.

[0043] The inner reaction chamber 2 is located inside the outer liquid chamber 3. The top of the inner reaction chamber 2 has an opening that is sealed and connected to the lower part of the upper sealing cover 1. The outer wall of the inner reaction chamber 2 does not contact the inner wall of the outer liquid chamber 3.

[0044] Heating device 21 is connected to upper sealing cover 1 and extends into inner reaction chamber 2;

[0045] Solid heat source 22 is located inside the inner reaction chamber 2. After being heated by heating device 21, it forms a high-temperature molten material that can break through the inner reaction chamber 2.

[0046] Pressure relief ports 7, at least one pair, are symmetrically arranged on the side wall of the outer liquid chamber 3, forming a tubular structure extending outward from the opening on the side wall of the outer liquid chamber 3;

[0047] The blasting device 4 has one end connected to the outlet end of the pressure relief port 7;

[0048] The sensor assembly has its probe end inserted into the outer liquid chamber 3 to measure the temperature and pressure of the liquid working medium 33 inside the outer liquid chamber 3;

[0049] The electronic controller, typically a PLC controller, has its signal input terminal connected to the signal output terminal of the sensor assembly, and its signal output terminal connected to the control terminal of the heating device 21.

[0050] The other end of the blasting device 4 is connected to a focusing shield 5; the focusing shield 5 has a tapered cylindrical structure, and the focusing shield 5 is connected to the other end of the blasting device 4 through the large-diameter end, while the small-diameter end serves as the focusing port.

[0051] The blasting device 4 includes a rupture disc 41, a clamp 42, and a flange 43. One end of the clamp 42 is connected to the outlet end of the pressure relief port 7, and the rupture disc 41 is clamped inside the clamp 42. The flange 43 connects the other end of the clamp 42 to the large-diameter end of the shaped charge hood 5. The rupture disc 41 is detachable. The clamp 42 and the flange 43 are connected by hexagon head bolts 6.

[0052] Both the outer liquid chamber 3 and the inner reaction chamber 2 are cylindrical structures with open tops. There are two pairs of pressure relief ports 7, arranged vertically on the side wall of the outer liquid chamber 3. The axes of the two pressure relief ports 7 arranged vertically on the same side intersect with the same generatrix on the side wall of the outer liquid chamber 3. The outer liquid chamber 3 is a three-layer composite structure: the inner lining is a molybdenum-titanium-zirconium alloy that is in direct contact with the molten metal, the middle pressure-bearing layer is a nickel-based alloy, and the outer protective layer is a carbon fiber composite material.

[0053] The inner reaction chamber 2 is made of copper and its inner wall is coated with a zirconium oxide coating. The bottom plate or side wall of the inner reaction chamber 2 is locally weakened, and the wall thickness of the weakened area is less than that of the non-weakened area.

[0054] The sensor unit includes a temperature sensor 31 and a pressure sensor 32; both the temperature sensor 31 and the pressure sensor 32 are installed inside the upper sealing cover 1, and their probes extend into the outer liquid chamber 3.

[0055] The solid heat source 22 is aluminothermic agent; the liquid working medium 33 is deionized water or a mixed solution of water and ethanol.

[0056] A pre-fracture method for ore bodies based on the principle of steam explosion includes the following steps:

[0057] S1. Drilling Positioning: Determine the drilling location, depth, and azimuth based on the mechanical properties of the target ore body and the pre-splitting requirements;

[0058] S2. Device loading: A solid heat source 22 is loaded and encapsulated in the inner reaction chamber 2, and a liquid working medium 33 is injected into the outer liquid chamber 3. The inner reaction chamber 2 and the outer liquid chamber 3 are then sealed by the upper sealing cover 1.

[0059] S3. Directional deployment: Place the device into the borehole and adjust the position of the device so that the energy focusing port of the energy focusing cover 5 faces the preset crack propagation surface;

[0060] S4. Drill hole sealing: Cement mortar is injected into the depth of the drill hole using a cement sealing pump, and a seal is achieved after curing.

[0061] S5. Energy Trigger: The electronic controller ignites the solid heat source 22 in the inner reaction chamber 2 through the heating device 21. The high-temperature melt generated by the solid heat source 22 through the heat source reaction quickly melts through the weakened zone of the inner reaction chamber 2 and rushes into the liquid working medium 33 at high speed, triggering a steam explosion. After the instantaneous high pressure generated by the explosion reaches the rated pressure of the rupture disc 41, the rupture disc 41 ruptures. The high-temperature and high-pressure fluid in the outer liquid chamber 3 is converged and accelerated by the energy-concentrating cover 5 to form a high-speed jet, which directionally impacts the preset fracture propagation surface, thereby generating and expanding fractures in the ore body.

[0062] This invention converts steam explosion energy into controllable fracturing force, enabling controllable explosion direction and adjustable peak pressure of 5-30 MPa. It solves the problems of large vibration in traditional blasting and difficulty in sealing hydraulic fracturing, and has the advantages of being green and safe with an energy utilization rate of >85%.

[0063] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are exemplary and intended to explain the present invention, but should not be construed as limiting it. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0064] See Figure 1-4 As shown, this embodiment pertains to a bauxite mine in Shanxi Province.

[0065] This invention achieves pre-fracture of ore bodies based on the steam explosion effect induced by the interaction between molten material and coolant. Its physical essence is as follows: when high-temperature molten metal enters a low-boiling-point coolant, a large amount of the molten metal's internal energy is transferred into the coolant, causing a sudden increase in pressure. Specifically, when the high-temperature molten metal encounters water, it undergoes intense heat exchange and forms a steam film on the metal surface. When this steam film becomes unstable and collapses, the cooling water comes into direct contact with the high-temperature molten metal, causing a rapid increase in the heat exchange area between the cooling water and the molten metal. A large amount of steam evaporates in a very short time. Due to the rapid expansion of the steam volume, some steam is generated inside the metal or at the metal covering but cannot escape in time. The enormous pressure diffuses outwards, resulting in a steam explosion.

[0066] Based on the above principles, such as Figure 1 , 2 As shown, this embodiment provides a pre-fracture device for ore bodies based on the principle of steam explosion, including an upper sealing cover 1, an inner reaction chamber 2, an outer liquid chamber 3, a blasting device 4, a focusing cover 5, hexagonal head bolts 6, and pressure relief ports 7. The pressure relief ports 7 are located on the left and right sides of the outer liquid chamber 3, distributed at 180 degrees, with two pressure relief ports 7 on each side. The inner reaction chamber 2 and the outer liquid chamber 3 are fitted and sealed by the upper sealing cover 1 to encapsulate a high-temperature solid heat source 22. The blasting device 4 is fitted with the pressure relief ports 7 by the hexagonal head bolts 6, and the focusing cover 5 is connected to the blasting device 4 by the hexagonal head bolts 6.

[0067] The assembly sequence of the device is as follows: First, a fixed amount of liquid working fluid 33 is loaded into the outer liquid chamber 3, ensuring that the liquid working fluid 33 meets the requirements for steam explosion while preventing overflow after being placed into the inner reaction chamber 2. Then, the inner reaction chamber 2, containing a fixed amount of solid heat source 22, is placed into the outer liquid chamber 3. Next, the upper sealing cover 1, along with the heating device 21, is placed inside the inner reaction chamber 2. Simultaneously, the upper sealing cover 1, along with the temperature sensor 31 and pressure sensor 32, is placed into the outer liquid chamber 3. Finally, the outer liquid chamber 3, the inner reaction chamber 2, and the upper sealing cover 1 are connected using hexagonal head bolts 6. A rupture disc 41 is installed at the pressure relief port 7 on the side surface of the outer liquid chamber 3. The rupture disc 41 is completely sealed by a clamp 42. The clamp 42 is connected to the outside of the energy-concentrating cover 5. The energy-concentrating cover 5 and the clamp 42 are connected by a flange 43. Figure 1 , 2 As shown.

[0068] The inner reaction chamber 2 includes a heating device 21, a solid heat source 22, a tungsten wire 23, etc. One end of the heating device 21 is connected to a power source via a cable, and the other end is connected to the tungsten wire 23. The tungsten wire 23 is buried 5mm deep inside the solid heat source 22. When the tungsten wire 23 continues to heat up to the ignition point of the solid heat source 22, it triggers a combustion reaction.

[0069] The solid heat source 22 in the inner reaction chamber 2 is a thermite, which is heated by a heating device 21 connected to a tungsten wire 23. When the tungsten wire 23 is heated to the ignition temperature of the thermite by the electrically powered heating device 21, a local reaction is initiated in the thermite in contact with it. The heat released by this initial reaction is sufficient to trigger a self-propagating reaction in the remaining thermite. The thermite reaction process releases a large amount of heat and causes its reaction products to reach a molten state. The reaction formula is:

[0070]

[0071] In the formula, granular materials are used. and Fe 2 O 3. A reaction occurs, and the product is in a molten state.

[0072] In some embodiments, the inner reaction chamber 3 adopts a copper shell structure, on which honeycomb-shaped weakening zones are pre-etched, reducing the wall thickness of the copper shell at the weakening zones to approximately 0.3 mm. This structural design effectively reduces the energy required for the aluminothermic reaction to break through the copper shell. Simultaneously, the inner surface of the copper shell is covered with zirconium oxide (ZrO2). ZrO 2) Coating. This coating interacts with copper at high temperatures to form a low-melting-point eutectic phase, significantly reducing the temperature threshold at which the copper shell melts through, from approximately 1085°C for pure copper to approximately 820°C. This is due to the coating of zirconium oxide (…). ZrO 2) The melting point of the coated copper shell is significantly lower than the aluminothermic reaction temperature, and the surface of the copper shell is pre-etched with honeycomb-shaped weakening zones (the shell walls in these zones are thinner). Under the action of internal high pressure, the molten reaction products preferentially spray out at high speed from the weakening zones. This high pressure originates from the large amount of gas released by the aluminothermic reaction and the rapid increase in internal gas pressure caused by the high temperature.

[0073] The outer liquid chamber 3 contains a liquid working fluid 33, a temperature sensor 31, and a pressure sensor 32. The temperature sensor 31 and pressure sensor 32 are fixed on the upper sealing cover 1 and electrically connected to the electronic controller (not shown in the figure). The outer liquid chamber 3 has symmetrically distributed pressure relief ports 7 on both sides. The outer liquid chamber 3 can enclose the inner reaction chamber 2. When the solid heat source 22 in the inner reaction chamber 2 is injected into the liquid working fluid 33 in the outer liquid chamber 3 at a certain initial velocity, the high-speed jet formed by the solid heat source 22 enters the liquid working fluid 33 and undergoes violent fragmentation. The contact area between the jet and the liquid working fluid 33 increases sharply, thereby significantly enhancing the subsequent steam explosion intensity (the intensity of the explosion pressure wave is closely related to the fragmentation rate and degree of the molten metal), and ultimately improving the overall energy release power.

[0074] The outer liquid chamber 3 primarily experiences steam explosions and needs to withstand extremely high pressures. When the outer liquid chamber is a one-piece structure, it can be forged from stainless steel. Because the outer liquid chamber 3 has a cylindrical structure and the pressure relief ports 7 are located on both sides of the outer liquid chamber 3, directional pre-fracture of the target ore body can be achieved based on the position of the adjustment device. This allows for the pre-fracture of harder ore bodies, improving production efficiency.

[0075] The blasting device 4 includes a rupture disc 41, a clamp 42, and a flange 43. The rupture disc 41 is located at the junction of the pressure relief port 7 and the energy-concentrating cover 5, which is the first pressure-bearing surface. The flange 43 protrudes outward from the outer liquid chamber 3. The energy-concentrating cover 5 is pre-tightened by hexagonal head bolts 6. The positioning reference is the welding distance between the rupture disc 41 and the copper shell. 0.1mm (seamless fit); the flange 43 has an extension length of 15mm; the diameter of the rupture disc 41 is exactly the same as the diameter of the pressure relief port 7; the inlet diameter of the energy-concentrating hood 5 is 50mm and the outlet diameter is 20mm.

[0076] When the pressure in the outer liquid chamber 3 reaches the preset pressure, the rupture disc 41 breaks, allowing high-temperature, high-pressure steam to enter the energy-concentrating hood 5 through the pressure relief port 7. The energy-concentrating hood 5 is a gradually narrowing energy-concentrating channel, which allows the ejected high-temperature steam to further increase its speed and significantly increase its fluid kinetic energy, thus more powerfully fracturing the target ore body. The sequence of high-temperature steam ejection is: pressure relief port → rupture disc → flange → energy-concentrating hood.

[0077] The peak pressure of a steam explosion can be used to effectively fracture the aluminum ore body based on thermodynamics and a dynamic model of steam explosion. The calculation formula is as follows:

[0078]

[0079] In the formula: This is the peak pressure of a steam explosion. For the specific heat capacity of steam, take It is 1.3; The mass of the molten metal; is the specific heat capacity of the metal; The initial temperature; The final temperature; The volume of the outer liquid chamber 3 minus the inner reaction chamber 2; This represents the uniaxial tensile strength of the bauxite body.

[0080] The uniaxial compressive strength of the bauxite body is The uniaxial tensile strength is conservatively estimated. (Based on rock mechanics: the tensile strength of hard rocks such as bauxite and granite is typically 1 / 3 of their compressive strength.) ,Pick (for safety margin), if In this case, a steam explosion is sufficient to pre-fracture the ore body.

[0081] The heat energy released by molten metal This energy is used to heat and evaporate water. When the mass of molten metal is 2 kg and the mass of water is 0.5 kg, the peak pressure of the steam explosion can be calculated to be about 25 MPa. The tensile strength of the ore body is 6.67 MPa. The steam explosion is sufficient to pre-fracture the ore body.

[0082] radius of the ore body crushing zone R c According to the formula The calculation results in this embodiment are approximately 0.29m.

[0083] In the formula, r 0 represents the borehole radius; P max This is the peak explosion pressure; A coefficient related to rock properties; This represents the uniaxial compressive strength of the bauxite body.

[0084] Meanwhile, the radius of the fracture zone in the ore body According to the formula The calculation results in this embodiment are approximately 0.52m.

[0085] In the formula, β is the stress wave attenuation coefficient; This represents the uniaxial tensile strength of the bauxite body.

[0086] In this embodiment, the explosive force was sufficient, and the resulting cracks were of a regular shape.

[0087] The ore body pre-fracture method based on the steam explosion principle of this invention is implemented using the ore body pre-fracture device based on the steam explosion principle described in any of the above embodiments, and includes the following steps:

[0088] S1: Drilling Design and Construction: Based on the lithology, hardness (such as Protodyakonov coefficient f), joint development, and pre-fracture targets of the target ore body, the location, depth, dip angle, and spacing of the boreholes are determined through theoretical calculations and numerical simulations (such as finite element analysis).

[0089] In some embodiments, for ore cutting into extremely hard metal ore bodies: horizontal fan-shaped deep holes are drilled within the ore body, with a hole depth of up to 15-20m, and the hole spacing is determined to be 0.8-1.2m based on the blastability index of the ore and rock.

[0090] S2: Device Loading: Open the upper sealing cover 1 and quantitatively load a solid heat source 22 into the inner reaction chamber 2, ensuring a tight filling. The solid heat source 22 can be a thermite or other metal redox system. Quantitatively inject a low-boiling-point liquid working fluid 33 into the outer liquid chamber 3. The liquid working fluid 33 can be deionized water or a mixture of water and ethanol, which effectively lowers the boiling point of the liquid working fluid 33 and increases the explosive power. The injection volume is three-quarters of the volume of the outer liquid chamber 3 to ensure sufficient space for vapor expansion. Align the upper sealing cover 1, equipped with the heating device 21, with the outer liquid chamber 3 and the inner reaction chamber 2, and use fasteners (such as hexagonal head bolts 6) for a sealed connection, ensuring the overall sealing of the device is sufficient to withstand the expected vapor explosion pressure.

[0091] S3: Downhole directional installation: Using the matching delivery rod, slowly feed the assembled device into the borehole design depth described in step S1. Subsequently, adjust the circumferential angle of the device by rotating the delivery rod to ensure that the energy focusing direction of the energy focusing shroud 5 connected to the outlet end of its pressure relief channel is precisely aligned with the preset fracture propagation surface. After installation, lead the cable of the heating device 21 out of the borehole and connect it to the electronic controller.

[0092] S4: Borehole Sealing: Cement mortar is injected deep into the borehole using a cement sealing pump, and a seal is achieved after it solidifies. Sealing the borehole is to concentrate the blasting energy into the target ore body and prevent energy leakage along the borehole.

[0093] S5: Energy Triggering and Controllable Fracturing: The electronic controller is activated to supply power to the heating device 21. The heating device 21 ignites the solid heat source 22 in the inner reaction chamber 2. The high-temperature molten material generated by the reaction of the solid heat source 22 rapidly melts through the weakened zone of the inner reaction chamber 2 and rushes into the liquid working fluid 33 at high speed, triggering a steam explosion. After the instantaneous high pressure generated by the explosion reaches the rated pressure of the rupture disc 41, the rupture disc 41 ruptures. The high-temperature and high-pressure fluid is converged and accelerated by the energy-concentrating shroud 5 to form a high-speed jet, which directionally impacts the borehole wall, generating and expanding the dominant fracture within the ore body. During the process, the temperature sensor 31 and pressure sensor 32 detect data in real time, and the electronic controller performs closed-loop control according to the preset safety threshold to ensure process safety.

[0094] The device structure, connection method, material selection, parameter range, and working process of the present invention have been described in detail above with reference to specific embodiments. It should be emphasized that these specific parameters and details are for illustrative purposes only and are not intended to limit the present invention. Under the premise of the inventive concept, those skilled in the art can make various modifications, substitutions, or combinations to the above embodiments, and all such modifications should be considered to fall within the protection scope defined by the claims of the present invention.

Claims

1. A pre-fracture device for ore bodies based on the principle of steam explosion, characterized in that, include: The outer liquid chamber (3) has an opening at its top, and an upper sealing cover (1) is installed at the opening. The chamber is filled with liquid working fluid (33). The inner reaction chamber (2) is located inside the outer liquid chamber (3). The top of the inner reaction chamber (2) has an opening and the opening is sealed and connected to the bottom of the upper sealing cover (1). The outer wall of the inner reaction chamber (2) does not contact the inner wall of the outer liquid chamber (3). The heating device (21) is connected to the upper sealing cover (1) and extends into the inner reaction chamber (2); A solid heat source (22) is located inside the inner reaction chamber (2). After being heated by the heating device (21), it forms a high-temperature molten substance that can break through the inner reaction chamber (2). At least one pair of pressure relief ports (7) are symmetrically arranged on the side wall of the outer liquid chamber (3) and are tubular structures extending outward from the opening on the side wall of the outer liquid chamber (3). The blasting device (4) is connected at one end to the outlet end of the pressure relief port (7); The sensor assembly has its probe end inserted into the outer liquid chamber (3) to measure the temperature and pressure of the liquid working medium (33) inside the outer liquid chamber (3); The electronic controller has its signal input terminal connected to the signal output terminal of the sensor assembly, and its signal output terminal is connected to the control terminal of the heating device (21). The other end of the blasting device (4) is connected to a focusing shield (5); the focusing shield (5) has a tapered cylindrical structure, and the focusing shield (5) is connected to the other end of the blasting device (4) through the large-diameter end, while the small-diameter end serves as the focusing port.

2. The ore body pre-fracture device based on the steam explosion principle as described in claim 1, characterized in that, The blasting device (4) includes a rupture disc (41), a clamp (42) and a flange (43). One end of the clamp (42) is connected to the outlet end of the pressure relief port (7). The rupture disc (41) is clamped inside the clamp (42). The flange (43) is connected between the other end of the clamp (42) and the large-diameter end of the energy-concentrating hood (5).

3. The ore body pre-fracture device based on the steam explosion principle as described in claim 2, characterized in that, Both the outer liquid chamber (3) and the inner reaction chamber (2) are cylindrical structures with open tops. There are two pairs of pressure relief ports (7), arranged vertically on the side wall of the outer liquid chamber (3). The axes of the two pressure relief ports (7) arranged vertically on the same side intersect with the same generatrix on the side wall of the outer liquid chamber (3). The outer liquid chamber (3) is a three-layer composite structure: the inner lining is a molybdenum-titanium-zirconium alloy that is in direct contact with the molten metal, the middle pressure-bearing layer is a nickel-based alloy, and the outer protective layer is a carbon fiber composite material.

4. The ore body pre-fracture device based on the steam explosion principle as described in claim 3, characterized in that, The inner reaction chamber (2) is made of copper and its inner wall is coated with a zirconium oxide coating. The bottom plate or side wall of the inner reaction chamber (2) is locally weakened, and the wall thickness of the weakened area is less than that of the non-weakened area.

5. The ore body pre-fracture device based on the steam explosion principle as described in claim 4, characterized in that, The sensor assembly includes a temperature sensor (31) and a pressure sensor (32); both the temperature sensor (31) and the pressure sensor (32) are installed inside the upper sealing cover (1), and the probe ends extend into the outer liquid chamber (3).

6. The ore body pre-fracture device based on the steam explosion principle as described in claim 5, characterized in that, The solid heat source (22) is aluminothermic agent; the liquid working medium (33) is deionized water or a mixed solution of water and ethanol.

7. A method for pre-fracture of ore bodies based on the principle of steam explosion, implemented using the ore body pre-fracture device based on the principle of steam explosion as described in any one of claims 4-6, characterized in that, Includes the following steps: S1. Drilling Positioning: Determine the drilling location, depth, and azimuth based on the mechanical properties of the target ore body and the pre-splitting requirements; S2. Device loading: A solid heat source (22) is loaded and sealed in the inner reaction chamber (2), and a liquid working medium (33) is injected into the outer liquid chamber (3). The inner reaction chamber (2) and the outer liquid chamber (3) are sealed by the upper sealing cap (1). S3. Directional deployment: Place the device into the borehole and adjust the position of the device so that the energy focusing port of the energy focusing cover (5) faces the preset crack propagation surface; S4. Drill hole sealing: Cement mortar is injected into the depth of the drill hole using a cement sealing pump, and a seal is achieved after curing. S5. Energy Trigger: The electronic controller ignites the solid heat source (22) in the inner reaction chamber (2) through the heating device (21). The high temperature melt generated by the solid heat source (22) through the heat source reaction quickly melts through the weakened area of ​​the inner reaction chamber (2) and rushes into the liquid working medium (33) at high speed, triggering a steam explosion. After the instantaneous high pressure generated by the explosion reaches the rated pressure of the rupture disc (41), the rupture disc (41) ruptures. The high temperature and high pressure fluid in the outer liquid chamber (3) is accelerated by the energy-concentrating cover (5) to form a high-speed jet, which directionally impacts the preset fracture expansion surface, thereby generating and expanding fractures in the ore body.

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