An experimental method and device for mechanically crushing hard rock assisted by a flame jet

Abstract

An experimental method and an experimental device for mechanically crushing hard rock assisted by a flame jet. The method includes: selecting a hard rock specimen, subjecting the hard rock specimen to triaxial loading in the X, Y, and Z directions, with each face corresponding to a load. When the triaxial stress state of the hard rock specimen is consistent with the in-situ rock stress state, remove the load in the X direction, and use the face from which the stress is removed in the X direction of the hard rock specimen as the working face. Apply the flame jet to the working face of the hard rock specimen to conduct thermal spalling on the working face until the peeled fragments no longer eject, and then remove the flame jet. Gradually bring the pick into contact with the thermal spalling pit of the hard rock specimen under the loading of the X-direction load, and realize the intrusion and crushing of the working face of the hard rock specimen with the increase of the X-direction load, and record the stress-displacement-time relationship curve of the pick during the loading process of the X-direction load. The present invention can provide theoretical guidance for the realization of mechanized continuous and efficient hard rock crushing in hard rock mines by thermal-assisted mechanical rock drilling.

Description

Technical Field

[0001] The present invention relates to the technical field of non-explosive continuous mechanized mining in hard rock mines, and particularly relates to a test method and a test device for mechanically crushing hard rock assisted by a flame jet. Background Art

[0002] Since fully mechanized mining replaced blasting mining in the coal mining field, the coal output has increased several times, providing an energy guarantee for China's economic development. However, there have been many problems when rock drilling equipment cuts rocks in metal hard rock mines, such as hard rocks being difficult to cut, cutting tools being extremely easy to wear, low rock drilling efficiency, high costs, etc. Therefore, at present, traditional blasting mining methods are still mainly used in metal hard rock mines, but there are many potential safety hazards in blasting mining methods. Conducting blasting work requires filing for approval with the public security department, and the discontinuity of the blasting operation process leads to low mining efficiency in hard rock mines. Therefore, it is necessary to improve the rock breaking performance and working life of rock drilling equipment to achieve mechanized continuous mining in metal hard rock mines, thereby improving the mining efficiency of hard rock metal mines and ensuring safety, which is of great significance for the rapid development of China's economy and ecological environment protection.

[0003] To achieve non-explosive continuous mechanized mining in metal hard rock mines based on the existing rock drilling equipment in the prior art, it is necessary to start from reducing the strength of hard rocks and improving the material properties of rock breaking tools. However, high-performance metal materials often have high costs and low yields, and are mainly used in high-end fields such as aerospace. Existing research shows that large thermal stresses will be generated inside rocks at high temperatures, thus significantly reducing the rock strength. Therefore, thermal rock breaking provides a new idea for hard rock crushing.

[0004] Since the 1940s, people have been researching the feasibility of thermal rock breaking and introducing high-temperature rock breaking methods such as microwaves, lasers, and plasma flames, but none of them have achieved good results. Among them, microwaves are not applicable to rocks because they are affected by the dielectric constant of minerals and basically do not heat quartz, and laser heating requires high-power heaters and has high costs. At present, there is no mature and reliable test equipment to carry out experimental research on the cutting characteristics of rocks after thermal exfoliation under in-situ stress conditions, and the theory of thermal-assisted mechanical rock drilling is not yet perfect.

[0005] In order to have a deeper understanding of the mechanism of thermal-assisted mechanical rock breaking, promote the research and development of non-explosive continuous mining rock drilling equipment in hard rock mines, accelerate the transformation of metal hard rock mines from traditional blasting mining to non-explosive continuous mechanized mining, ensure the stable supply of China's metal resources, meet the national environmental protection and safety policies, and accelerate the construction of green mines and intelligent mines, based on the characteristics of the original rock itself and the stress conditions of the surrounding environment, it is very important to develop a test device and method for mechanically crushing hard rock assisted by a flame jet. Summary of the Invention

[0006] Based on this, the present invention provides a test method and a test device for flame jet-assisted mechanical hard rock fragmentation. In this test method, the rock under in-situ stress state is first thermally spalled by the flame jet to reduce the rock strength, and then the mechanical rock drilling method is used to fragment the rock, realizing the mechanized continuous and efficient hard rock fragmentation in hard rock mines by thermal-assisted mechanical rock drilling.

[0007] To achieve the above object, the present invention provides a test method for flame jet-assisted mechanical hard rock fragmentation, which includes the following steps:

[0008] S1. Select a hexahedron hard rock specimen and simulate the stress condition of the original rock in the following way:

[0009] Apply triaxial loading to the hard rock specimen in the X, Y, and Z directions, with each face corresponding to a load until the triaxial stress state of the hard rock specimen is consistent with the original rock stress state. Then remove the load in the X direction. The hard rock specimen uses the face from which the stress is removed in the X direction as the working face, while the stresses in the Y and Z directions remain unchanged.

[0010] S2. Use a flame jet that can move in the YZ plane and whose flame temperature and flame distance are adjustable to act on the working face of the hard rock specimen for thermal spalling until the observed peeled fragments no longer eject. Consider the thermal spalling completed and remove the flame jet. Then use the measurement and recording tool to record the morphology and size of the thermal spalling pit of the hard rock specimen, as well as the shape and size of the peeled fragments.

[0011] S3. Gradually bring the pick into contact with the thermal spalling pit of the hard rock specimen under the loading of the X-direction load. With the loading of the X-direction load, achieve the intrusion and crushing of the working face of the hard rock specimen, and simultaneously record and save the stress-displacement-time relationship curve of the pick during the loading process of the X-direction load.

[0012] As a further preferred technical solution of the present invention, according to the test requirements, repeat steps S2 and S3.

[0013] As a further preferred technical solution of the present invention, in step S3, the X-direction load provided to the pick is a static load, or a combination of a static load and a disturbance load, and the loading speed and impact frequency of the load are adjustable.

[0014] According to another aspect of the present invention, the present invention also provides a test device for the above test method of flame jet-assisted mechanical hard rock fragmentation, including:

[0015] A flame jet system for providing a flame jet to perform thermal spalling on the hard rock specimen;

[0016] A rock drilling system for mechanically fragmenting the hard rock specimen after thermal spalling; and

[0017] A true triaxial stress loading system for placing hard rock specimens, providing in-situ stress for the hard rock specimens during the test, and providing loading loads for the rock drilling system.

[0018] As a further preferred technical solution of the present invention, the flame jet system includes:

[0019] A combustion chamber having a gas mixing chamber and a nozzle;

[0020] An oxygen cylinder connected to the gas mixing chamber of the combustion chamber through a gas supply pipeline with a pressure reducer and a flow valve to provide oxygen for combustion;

[0021] A fuel gas cylinder connected to the gas mixing chamber of the combustion chamber through a gas supply pipeline with a pressure reducer and a flow valve to provide fuel gas for combustion;

[0022] An electronic igniter having an igniter and an ignition switch, the igniter being disposed near the nozzle of the combustion chamber, the ignition switch being away from the nozzle of the combustion chamber and connected to the igniter through a wire; and

[0023] A numerically controlled positioning and moving mechanism for carrying and moving the combustion chamber.

[0024] As a further preferred technical solution of the present invention, the numerically controlled positioning and moving mechanism includes a numerical control instrument panel, and a Y-direction linear motion module and a Z-direction linear motion module that are controlled by the numerical control instrument panel and are arranged in a cross shape. The Z-direction linear motion module is used to drive the Y-direction linear motion module to move along the Z direction, and the Y-direction linear motion module is used to drive the combustion chamber to move along the Y direction;

[0025] One end of the Y-direction linear motion module is provided with a fixture, the fixture is provided with a positioning hole in the X direction, the combustion chamber is arranged in the positioning hole and is locked and fixed by a first bolt, and the installation position of the combustion chamber on the fixture can be adjusted in the X direction.

[0026] As a further preferred technical solution of the present invention, the true triaxial stress loading system has a loading chamber for placing a hexahedral hard rock specimen. The loading chamber is formed by splicing six loading plates, and the six loading plates are respectively used to fit each face of the hard rock specimen one by one. Each of the loading plates is connected with a loading head in the X, Y or Z direction, and the loading head is connected with a power source, and the power source is used to output loading loads in the X, Y and Z directions.

[0027] As a further preferred technical solution of the present invention, the rock drilling system includes a pick and a connector. The connector is used to be locked and connected to one of the loading heads after removing the loading plate through a second bolt, and the pick is locked and connected to the connector through a third bolt.

[0028] As a further preferred technical solution of the present invention, the pick is a pick-shaped pick.

[0029] For the test method and test device for mechanically breaking hard rock assisted by flame jet of the present invention, by adopting the above technical solutions, the following beneficial effects can be achieved:

[0030] 1) By studying the hard rock thermal spalling mechanism and the cuttable characteristics of the hard rock after thermal spalling, the present invention provides theoretical guidance for realizing non-explosive continuous mining in hard rock mines by thermal-assisted mechanical rock breaking, which has important practical significance;

[0031] 2) The present invention can design the optimal thermal spalling flame parameters (flame temperature and flame distance) and rock drilling parameters (static pressure, loading rate, amplitude and frequency of disturbance load) matching different rock types in different strata, and provide parameters for the research and development of related thermal-assisted rock breaking equipment;

[0032] 3) The present invention uses a flame jet to perform thermal spalling on the rock. The entire thermal spalling test generally ends within 1 - 2 minutes, which can match the rock drilling speed of the pick. Based on this idea, a large flame chamber integrating multiple nozzles is designed, so as to hopefully achieve the spatio-temporal matching of thermal spalling at the mine site and mechanical rock drilling of mining equipment. Description of the Drawings

[0033] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0034] Figure 1 It is a method flow chart of an embodiment provided for the test method of mechanically breaking hard rock assisted by flame jet of the present invention;

[0035] Figure 2 It is the front view of the test device for mechanically breaking hard rock assisted by flame jet;

[0036] Figure 3 It is the side view of the test device for mechanically breaking hard rock assisted by flame jet;

[0037] Figure 4 It is the assembly schematic diagram of the pick-shaped pick.

[0038] In the figure: 1 - pressure reducer; 2 - flow valve; 3 - ignition switch; 4 - Y-direction linear motion module; 5 - igniter; 6 - loading plate; 7 - Z-direction linear motion module; 8 - fixture; 9 - first bolt; 10 - fuel gas cylinder; 11 - oxygen cylinder; 12 - gas mixing chamber; 13 - numerical control instrument panel; 14 - nozzle; 15 - hard rock sample; 16 - pick-shaped pick; 17 - second bolt; 18 - connector; 19 - third bolt; 20 - loading head.

[0039] The realization of the object, functional features and advantages of the present invention will be further described with reference to the embodiments and the accompanying drawings. Detailed implementation manners

[0040] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation manners. Terms such as "upper", "lower", "left", "right", "middle" and "one" cited in the preferred embodiments are only for the convenience of clear narration, rather than used to limit the scope of implementation of the present invention. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the scope of implementation of the present invention.

[0041] Embodiment 1

[0042] Such as Figure 1 The test method for mechanically crushing hard rock assisted by flame jet includes the following steps:

[0043] 11. Select a hexahedron hard rock specimen and simulate the stress condition of the original rock in the following way:

[0044] Apply triaxial loading to the hard rock specimen in the X, Y, and Z directions, with each face corresponding to a load until the triaxial stress state of the hard rock specimen is consistent with the original rock stress state. Then remove the load in the X direction. The face of the hard rock specimen from which the stress is removed in the X direction is used as the working face, while the stresses in the Y and Z directions remain unchanged;

[0045] 12. Use a flame jet that can move in the YZ plane and whose flame temperature and flame distance are adjustable to act on the working face of the hard rock specimen to perform thermal spalling on the working face until the observed spalled fragments no longer eject. It is considered that the thermal spalling is completed and the flame jet is removed. Then use a measurement and recording tool to record the morphology and size of the thermal spalling pit of the hard rock specimen, as well as the shape and size of the spalled fragments;

[0046] 13. Use a pick to gradually contact the thermal spalling pit of the hard rock specimen under the loading of the X-direction load. As the X-direction load is applied, the working face of the hard rock specimen is invaded and crushed. At the same time, record and save the stress-displacement-time relationship curve of the pick during the loading process of the X-direction load. In this step, the X-direction load provided to the pick is a static load, or a combination of a static load and a disturbance load, and the loading speed and impact frequency of the load are adjustable;

[0047] 14. Repeat steps 12 and 13.

[0048] It should be noted here that in the present application, the X, Y, and Z directions represent a three-dimensional direction coordinate. Among them, the X direction can be defined as any direction, not limited to the X direction in a specific occasion. The Y and Z directions are set with reference to the X direction.

[0049] Embodiment 2

[0050] As Figures 2 - 4 shown, the present invention proposes a test device for flame jet-assisted mechanical crushing of hard rock, taking a cube or cuboid hard rock specimen 15 as the test object. The system includes a flame jet system for providing a flame jet to thermally spall the hard rock specimen 15, a rock drilling system for mechanically crushing the hard rock specimen 15 after thermal spalling, and a true triaxial stress loading system for placing the hard rock specimen 15 and providing the in-situ stress for the hard rock specimen 15 in the test and the loading load for the rock drilling system.

[0051] In a specific implementation, in order to perform heat treatment on a fixed point or the entire surface of the hard rock specimen 15, the flame jet system includes:

[0052] A combustion chamber having a gas mixing chamber 12 and a nozzle 14. The nozzle 14 is connected to the front end of the gas mixing chamber 12 for jetting a flame, and the gas mixing chamber 12 is used to mix the input fuel gas and oxygen and then transport them to the nozzle 14;

[0053] An oxygen cylinder 11, connected to the gas mixing chamber 12 of the combustion chamber through a gas supply pipeline with a pressure reducer 1 and a flow valve 2 to provide oxygen for combustion;

[0054] A fuel gas cylinder 10, connected to the gas mixing chamber 12 of the combustion chamber through a gas supply pipeline with a pressure reducer 1 and a flow valve 2 to provide fuel gas for combustion;

[0055] An electronic igniter 5 having an igniter 5 and an ignition switch 3. The igniter 5 is arranged close to the nozzle 14 of the combustion chamber, and the ignition switch 3 is far from the nozzle 14 of the combustion chamber and is connected to the igniter 5 through a wire; and

[0056] A numerically controlled positioning and moving mechanism for carrying and moving the combustion chamber.

[0057] In a specific embodiment, the numerically controlled positioning and moving mechanism includes a numerically controlled instrument panel 13, and a Y-direction linear motion module 4 and a Z-direction linear motion module 7 that are controlled by the numerically controlled instrument panel 13 and are arranged in a cross shape. The Z-direction linear motion module 7 is used to drive the Y-direction linear motion module 4 to move along the Z direction, and the Y-direction linear motion module 4 is used to drive the combustion chamber to move along the Y direction. That is, the Y-direction guide rail of the Y-direction linear motion module 4 and the Z-direction guide rail of the Z-direction linear motion module 7 are cross-shaped, and the slider of the Y-direction linear motion module 4 is fixedly connected to the slider of the Z-direction linear motion module 7. The combustion chamber is arranged at one end of the Y-direction guide rail of the Y-direction linear motion module 4. The numerically controlled instrument panel 13 is used to input parameters and control instructions to adjust and control the movement of the Y-direction linear motion module 4 and the Z-direction linear motion module 7, so as to drive the combustion chamber to move in the YZ plane. The Y-direction linear motion module 4 and the Z-direction linear motion module 7 can be selected from conventional rail-type linear motion modules on the market, and their detailed structures and working principles will not be elaborated here.

[0058] A fixture 8 is provided at one end of the Y-direction linear motion module 4. The fixture 8 is provided with a positioning hole along the X direction. The combustion chamber is arranged in the positioning hole and is locked and fixed by a first bolt 9. Moreover, the installation position of the combustion chamber on the fixture 8 can be adjusted along the X direction. During use, by adjusting the combustion chamber along the X direction, the distance between the combustion chamber nozzle 14 and the hard rock specimen 15 can be adjusted.

[0059] The true triaxial stress loading system has a loading chamber for placing the hexahedral hard rock specimen 15. The loading chamber is formed by splicing six loading plates 6. The six loading plates 6 are respectively used to fit each face of the hard rock specimen 15 one by one. Each loading plate 6 is connected with a loading head 20 in the X, Y or Z direction. The loading head 20 is connected with a power source. The power source is used to output loading loads in the X, Y and Z directions. The power source can adopt a hydraulic cylinder. The true triaxial stress loading system in the present invention belongs to the prior art, and its detailed structure and principle will not be described in detail here. In this embodiment Figure 2 and Figure 3 in, for the sake of concise drawing, the power source and the loading head 20 of the true triaxial stress loading system are not shown. The load directions corresponding to the respective loading plates 6 are the directions indicated by the arrows.

[0060] The rock drilling system includes a pick and a connector 18. The connector 18 is used to be locked and connected to one of the loading heads 20 after removing the loading plate 6 through a second bolt 17. The pick is locked and connected to the connector 18 through a third bolt 19. The pick is a pick-shaped pick 16. Of course, according to the test requirements, other types of picks can also be adopted, which will not be limited here.

[0061] Embodiment 3

[0062] The present invention provides a test method using the above test device for flame jet-assisted mechanical hard rock fragmentation. In this embodiment, a granite sample with dimensions of 200×200×100 mm is processed by a cutting machine as the hard rock sample 15. The specific test method includes the following steps:

[0063] Step S1: Select a hexahedral hard rock sample 15 to simulate the stress state of the original rock. Apply loads to the six faces of the hard rock sample 15 using a true triaxial stress loading system for three-directional loading in the X, Y, and Z directions until the three-directional stress state of the hard rock sample 15 is consistent with the original rock stress state. Then remove the load in the X direction (i.e., remove the loading plate 6 on the YZ plane of the hard rock sample 15). The side of the hard rock sample 15 with the stress removed in the X direction serves as the working face, while the stresses in the Y and Z directions remain unchanged.

[0064] Step S2: Use a flame jet that can move in the YZ plane and has adjustable flame temperature and flame distance to act on the working face of the hard rock sample for thermal spalling until the observed peeling fragments no longer eject. Consider the thermal spalling completed and remove the flame jet. Then use a measurement and recording tool to record the morphology and size of the thermal spalling pit on the hard rock sample, as well as the shape and size of the peeling fragments. The detailed operations of this step are as follows:

[0065] S2.1: Start the numerically controlled positioning and moving mechanism. Set the walking trajectory of the combustion chamber through the numerical control instrument panel 13. The numerically controlled directional moving device controls the Y-direction linear motion module 4 and the Z-direction linear motion module 7 so that the position of the nozzle 14 of the combustion chamber is directly in front of the center of the YZ wall surface of the hard rock sample 15.

[0066] S2.2: Adjust the installation position of the combustion chamber in the positioning hole according to the test requirements so that the distance between the nozzle 14 of the combustion chamber and the YZ wall surface of the hard rock sample 15 is controlled within the range of 1 cm to 6 cm, and then lock and fix it with the first bolt 9. In this test, once the test starts, the distance between the nozzle 14 and the hard rock sample 15 cannot be changed.

[0067] S2.3: Open the valve of the fuel gas cylinder 10 with acetylene as the fuel, adjust the pressure regulator 1 on the corresponding gas supply pipeline to control the pressure within the range of 0.05 MPa to 0.1 MPa, and adjust the corresponding flow valve 2. At this time, the acetylene gas is transported to the gas mixing chamber 12 of the combustion chamber through the gas supply pipeline.

[0068] S2.4: Press the ignition switch 3 to electronically ignite the igniter 5 to ignite the acetylene. At this time, the flame is small and there is thick smoke emerging;

[0069] S2.5. Open the valve of the oxygen cylinder 11, adjust the pressure reducer 1 on the corresponding gas supply pipeline to control the pressure between 0.2 MPa and 0.5 MPa, and slowly open the flow valve 2 so that oxygen supplies oxygen for the combustion of acetylene in the combustion chamber at a relatively low flow rate.

[0070] S2.6. Slowly increase the flow valve 2 controlling oxygen so that acetylene and oxygen burn to form an oxidizing flame, increasing the flame temperature and causing the hard rock specimen 15 to start thermal spalling. At the same time, the excess oxygen can be used to blow away the rock debris. When no more spalling fragments are ejected, it is considered that the thermal spalling is complete. During thermal spalling, if the entire surface of the hard rock specimen 15 needs to be thermally spalled, the walking trajectory of the combustion chamber can be controlled by the numerical control positioning and moving mechanism to spall the entire cross-section of the rock. During this process, since the flame will spread to the surrounding area after contacting the rock wall, the walking trajectory needs to ensure that the flame does not directly contact the loading plate 6 to avoid melting of the loading plate 6.

[0071] S2.7. After the thermal spalling is complete, first close the flow valve 2 of acetylene, then close the valve of the fuel gas cylinder 10, then close the flow valve 2 of oxygen, and finally close the valve of the oxygen cylinder 11 to prevent backfire.

[0072] S2.8. After the flame goes out, operate the numerical control instrument panel 13 to move the Y-direction guide rail completely away from the front of the hard rock specimen 15 to provide a drilling space for the mechanical drilling of the rock drilling system.

[0073] S2.9. To facilitate subsequent comprehensive analysis, use measuring and recording tools such as cameras and calipers to record the morphology and size of the thermal spalling pits on the hard rock specimen 15, as well as the shape and size of the spalling fragments.

[0074] Step S3. Gradually bring the pick into contact with the thermal spalling pit of the hard rock specimen 15 under the loading of the X-direction load. With the loading of the X-direction load, achieve the intrusion and crushing of the face of the hard rock specimen 15, and at the same time record and save the stress-displacement-time relationship curve of the pick during the loading process of the X-direction load. The detailed operation of this step is as follows:

[0075] S3.1. Connect the pick-shaped pick 16 to the X-direction loading head 20 of the true triaxial stress loading system with the connector 18, and lock and fix them with the second bolt 17 and the third bolt 19 respectively.

[0076] S3.2. Control the X-direction loading head 20 of the true triaxial stress loading system to drive the pick-shaped pick 16 fixed on the connector 18 to move towards the hard rock specimen 15 at a certain loading rate and slowly contact the spalling pit. With the progress of the loading, the hard rock specimen 15 is intruded and crushed by the pick-shaped pick 16, and at the same time record and save the stress-displacement-time relationship curve of the pick during the loading process of the X-direction load.

[0077] Preferably, if it is necessary to study the mechanism of continuous and efficient hard rock crushing, steps S2 and S3 can be repeated according to the test requirements, and thermal spalling and mechanical crushing can be carried out alternately.

[0078] Further preferably, if it is necessary to study the effects of the impact frequency of the pick, the loading rate, and the static pressure on the hard rock cutting performance (peak load of rock intrusion and crushing, penetration depth, disturbance time), after completing the above step S3, steps S2 and S3 can be repeated again. The static pressure applied in the X direction of the true triaxial stress loading system is set to 70% - 90% of the peak load corresponding to the intrusion and crushing of the hard rock sample 15 by the pick-shaped pick 16 in the original step S3. When the load reaches 70% - 90% of the peak load, the stress is kept unchanged. At this time, the hard rock sample 15 has not been crushed. Then, a disturbance load is provided to the pick-shaped pick 16 through the true triaxial stress loading system (this value is 10% - 30% of the peak load of the hard rock sample 15 for intrusion and crushing, and the frequency of the disturbance load can be controlled within 0 Hz - 70 Hz, and the sum of the disturbance load and the static pressure is equal to the peak load of rock intrusion and failure). In this way, the effects of the combined action of the static pressure and the disturbance load on the failure mode and fragmentation size of the rock sample can be studied. In addition, the effects of the loading rate on the failure mode and fragmentation size of the rock sample can also be studied by changing the loading rate of the loading head 20. Therefore, based on the above test method and principle, the effects on the failure mode and fragmentation size of the rock sample under single factor or multiple factors can be realized. During the specific test process, it can be flexibly selected according to the test requirements and will not be exemplified one by one here.

[0079] According to the rapid heating theory, it can be known that during the rapid heating process, the wall surface of the rock sample is in a compressive state, while the interior of the rock sample is in a tensile stress state. Thermal spalling is caused by the fact that the thermally induced compressive stress on the rock wall surface is much greater than the rock compressive strength. The significance of conducting a thermal spalling test on the rock in the in-situ stress state through a flame jet and recording the morphology and size of the spalling pits, as well as the size of the spalling debris, lies in that during thermal spalling, by adjusting the oxygen and acetylene ratio in the gas mixing chamber 12 to adjust the flame size, and the measurement data recorded during thermal spalling, a flame temperature can be obtained that results in the best spalling effect with the least melting of rock minerals. Similarly, by adjusting the distance between the nozzle 14 and the rock sample wall surface, the optimal flame distance for thermal spalling to avoid rock mineral melting at the same flame temperature can be obtained. The flame temperature and the flame distance will jointly have an impact. Therefore, experiments need to be repeated to obtain the best matching parameters. In addition, by selecting different types of hard rock, the applicability of the flame jet to various ores can be studied to obtain the optimal flame parameters required for thermal spalling of this type of ore, so as to form corresponding standards.

[0080] By conducting a comparison of rock drilling experiments on hard rock after thermal spalling and hard rock without thermal spalling, it is determined whether the cuttability of the rock after thermal spalling is significantly improved. Since the rock surface is thermally spalled during the heat treatment process, obvious thermal damage will also occur inside the rock under the action of tensile stress, so it is speculated that the peak load of rock fragmentation after thermal spalling will be lower. Secondly, static pressure loading, static pressure + disturbance loading and other loading methods are commonly used rock drilling indexes for studying rock cutting characteristics, and the rock drilling parameters that are most likely to break the rock after thermal spalling can be obtained.

[0081] In summary, through the flame jet assisted mechanical rock drilling test method and device of the present invention, the flame parameters corresponding to the best thermal spalling effect of different hard rocks and the best rock drilling parameters for mechanical rock drilling after thermal spalling of the rock can be obtained. The device and method can evaluate the feasibility of thermal-assisted mechanical rock drilling for high-strength hard rocks technically and theoretically, which has important guiding significance for improving the theory of thermal-assisted mechanical rock drilling and realizing non-explosive mechanized continuous mining in hard rock mines.

[0082] Research shows that heat treatment can greatly reduce the rock strength, and through experimental methods, the system and ideas can guide the upgrading and transformation of rock drilling equipment (such as roadheaders) at the hard rock mine site. For example, adding a large flame spraying device to the roadheader to achieve the spatio-temporal matching of mechanical rock drilling after thermal spalling first. It is expected to change some hard rock mines that are difficult to be mechanized and have to be converted to traditional blasting mining and have always used blasting mining into thermal-assisted mechanical rock drilling methods to achieve mechanized continuous mining at the hard rock mine site, which can greatly improve the operation efficiency and reduce the safety hazards brought by blasting operations. Therefore, it is of great significance to both green ecological construction and intelligent mine construction.

[0083] Although the specific implementation manners of the present invention have been described above, those skilled in the art should understand that these are only examples, and various changes or modifications can be made to this implementation manner without departing from the principle and essence of the present invention. The protection scope of the present invention is only defined by the appended claims.

Claims

1. An experimental method for mechanically crushing hard rock assisted by a flame jet, characterized in that, It includes the following steps: S1. Select a hexahedral hard rock specimen and simulate the stress condition of the original rock in the following way: Apply triaxial loading to the hard rock specimen in the X, Y, and Z directions, with each face corresponding to a load until the triaxial stress state of the hard rock specimen is consistent with the original rock stress state. Then remove the load in the X direction. The face of the hard rock specimen where the stress is removed in the X direction serves as the tunnel face, while the stresses in the Y and Z directions remain unchanged; S2. Use a flame jet that can move in the YZ plane and whose flame temperature and flame distance are adjustable to act on the tunnel face of the hard rock specimen to conduct thermal spalling on the tunnel face until the observed peeling fragments no longer eject. Consider the thermal spalling completed and remove the flame jet. Then use a measurement recording tool to record the morphology and size of the thermal spalling pit of the hard rock specimen, as well as the shape and size of the peeling fragments; S3. Use a pick to gradually contact the thermal spalling pit of the hard rock specimen under the loading of the X - direction load. With the loading of the X - direction load, achieve the intrusion and crushing of the tunnel face of the hard rock specimen, and simultaneously record and save the stress - displacement - time relationship curve of the pick during the loading process of the X - direction load.

2. The test method for mechanically crushing hard rock assisted by a flame jet according to claim 1, characterized in that, According to the test requirements, repeat steps S2 and S3.

3. The test method for mechanically crushing hard rock assisted by a flame jet according to claim 1, characterized in that In step S3, the X - direction load provided to the pick is a static load, or a combination of a static load and a disturbance load, and the loading speed and impact frequency of the load are adjustable.

4. An experimental device for the experimental method of flame jet-assisted mechanical hard rock fragmentation according to any one of claims 1-3, characterized in that, It includes: A flame jet system for providing a flame jet to conduct thermal spalling on the hard rock specimen; A rock drilling system for mechanically crushing the hard rock specimen after thermal spalling; And A true triaxial stress loading system for placing the hard rock specimen, providing the original rock stress for the hard rock specimen in the test, and providing a loading load for the rock drilling system.

5. The test device according to claim 4, wherein The flame jet system includes: A combustion chamber having a gas mixing chamber and a nozzle; An oxygen cylinder connected to the gas mixing chamber of the combustion chamber through a gas supply pipeline with a pressure reducer and a flow valve to provide oxygen for combustion; A fuel gas cylinder connected to the gas mixing chamber of the combustion chamber through a gas supply pipeline with a pressure reducer and a flow valve to provide fuel gas for combustion; An electronic igniter having an igniter and an ignition switch. The igniter is arranged near the nozzle of the combustion chamber, and the ignition switch is far from the nozzle of the combustion chamber and is connected to the igniter through a wire; and A numerically controlled positioning and moving mechanism for carrying and moving the combustion chamber.

6. The test device according to claim 5, characterized in that, The numerically controlled positioning and moving mechanism includes a numerical control instrument panel, and a Y - direction linear motion module and a Z - direction linear motion module that are controlled by the numerical control instrument panel and are arranged in a cross - shaped manner. The Z - direction linear motion module is used to drive the Y - direction linear motion module to move along the Z direction, and the Y - direction linear motion module is used to drive the combustion chamber to move along the Y direction; One end of the Y - direction linear motion module is provided with a fixture. The fixture is provided with a positioning hole in the X direction. The combustion chamber is arranged in the positioning hole and is locked and fixed by a first bolt, and the installation position of the combustion chamber on the fixture can be adjusted in the X direction.

7. The test device according to claim 4, characterized in that, The true triaxial stress loading system has a loading chamber for placing a hexahedral hard rock specimen. The loading chamber is formed by splicing six loading plates, and the six loading plates are respectively used to fit corresponding to each face of the hard rock specimen one by one. Each of the loading plates is connected with a loading head in the X, Y or Z direction, and the loading head is connected with a power source, and the power source is used to output loading loads in the X, Y and Z directions.

8. The test device according to claim 7, wherein The rock drilling system includes pick teeth and a connector. The connector is used to be locked and connected with one of the loading heads after removing the loading plate through a second bolt, and the pick teeth are locked and connected with the connector through a third bolt.

9. The test device according to claim 8, wherein, The pick teeth are pick-shaped pick teeth.

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