Method for preparing thin sample sheet from loose coal rock sample block

Abstract

The invention discloses a method for preparing a thin sample piece from a loose coal rock sample block, and relates to the technical field of coal rock sample glue wrapping. The method comprises the following steps: S1, observing cracks of a coal briquette sample; s2, wrapping the coal briquette sample with a thermal shrinkage film and a flexible rubber shell; s3, clamping and cutting the wrapped coal briquette sample to obtain a thin sample block; s4, removing the thermal shrinkage film and the flexible glue shell, and putting the thin sample block in glue boiling equipment for glue wrapping; s5, clamping and cutting the thin sample block along the bedding direction; s6, placing the thin sample block in glue boiling equipment for glue wrapping; s7, cutting 2-3 vertical surfaces along a direction vertical to the bedding direction, wherein the coal rock samples are exposed out of the vertical surfaces respectively; s8, placing the thin sample block in glue boiling equipment for glue wrapping; s9, placing the ground thin sample block in glue boiling equipment for glue wrapping; and S10, polishing to obtain a thin sample block. When the coal rock sample is cut before being wrapped with glue, the coal rock sample is sequentially wrapped with the thermal shrinkage film and the silica gel layer, and molybdenum wire cutting is combined, so that vibration damage is greatly reduced, and sample fragmentation is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of coal rock sample coating, and in particular to a method for preparing thin sample slices from loose coal rock sample blocks. Background Art

[0002] According to the characteristics of fragile coal blocks, tailor-made cutting, rubber boiling and grinding solutions are provided. Closely following the practical difficulties in coal and rock cutting (during the on-site mining and recovery process, the samples have been repeatedly affected by external forces, resulting in multiple cracking damages. They are not natural samples, but the fragile nature of coal and rock itself, coupled with the external environment, makes the fragmentation situation very complicated and difficult to control. In fact, for the purpose of buffering and mitigation, the fragmentation damage is reduced as much as possible. Because the compression test, tensile test, and hardness test of coal and rock must be tested through rigorous conditional experiments, in actual production work, the number of coal and rock samples recovered from mining is limited, and there are many coal and rock analysis projects to be carried out. There is no possibility and necessity to carry out conditional experiments on single samples for relevant mechanical tests.

[0003] There are problems with the coal block cutting method, which needs to be improved. There is no suitable clamp for clamping and cutting irregular coal blocks of about 10x10x10cm-15x15x15cm in size. The cutting is basically done by a single-chip cutting machine, which is not competent for cutting fragile natural coal rock samples (brittle, broken, and rotten). In actual production, coal rock samples collected from the site need to carry out various analysis tests, but in fact, due to the limited mining conditions, the number of samples obtained is limited. The ordinary single-chip cutting machine is repeatedly used to cut the required ones. Generally, the cutting machine is directly used for cutting. The cutting head vibrates greatly, and the coal is spoiled and brittle. The cracks it carries are very hidden and easy to break, so the whole sample cannot be obtained. Especially for rock and mineral analysis work, it is often necessary to take samples from locations containing specified geological information to reduce sample loss and damage. Solving production problems is becoming a key problem and a problem that needs to be solved urgently.

[0004] In the existing technology, the coal-rock boiling method is relatively old, the equipment is outdated, and the boiling process is simple and crude, which needs to be optimized. Both should be carried out at the same time.

[0005] When the sample is coated with glue, the boiling pot is placed on the electric heating wire heating plate to heat it until it is in a fluid state, and then the coal and rock samples are clamped by a clamp and placed in the pot to roll and coat with glue. There are obvious defects in the actual operation process: 1) When the glue is heated to a high temperature, it is easy to spray on the edge or outside of the heating plate, the equipment is simple and the operation is unsafe; 2) Because the heating is done from the bottom of the pot to the top, the temperature is uneven, the glue on the edge of the pot has solidified, and the glue boiling temperatures in the upper, middle and lower parts of the pot are inconsistent, resulting in inconsistent glue viscosity, causing more air to mix into the pot, generating a large number of bubbles that affect the glue boiling effect of coal blocks; 3) The amount of glue loaded into a single container is large, and the glue is easily broken or even exploded due to thermal expansion and contraction in a large and uneven heating environment; 4) It is difficult to maintain a constant temperature in the glue boiling equipment, and it is actually impossible to implement constant temperature control conditions, and it is impossible to use and boil rosin and turpentine to achieve accurate and reasonable use effects; 5) The traditional method of boiling glue takes a long time, more than half an hour. The current implementation of boiling glue in different temperature zones greatly shortens the boiling time and improves the boiling efficiency; 6) Cooking glue in a single container causes mixing of samples, which can easily contaminate the samples.

[0006] In actual production, the heating of coal blocks also has certain restrictions. Accurate and effective temperature control has a great influence on the effect of coal block glue boiling. The glue boiling ratio, temperature, air, viscosity changes, time, movement mode, etc. seriously restrict the penetration and filling effect of glue. Often after the glue is wrapped and dried, it is visible that there are many bubbles on the surface or inside of the glue layer, which actually causes the thin sample blocks after glue boiling to be loosely wrapped, affecting the cutting hardness of the sample blocks, grinding and polishing hardness (cracking, fragmentation, plane depression, etc.) due to various defects in glue boiling, equipment, heating conditions, and implementation of operations. Therefore, the optimization and transformation of the glue boiling method, equipment and method process transformation must be carried out simultaneously. Summary of the invention

[0007] The purpose of the present invention is to provide a method for preparing thin samples from loose coal rock samples, which can effectively solve the problems in the background technology.

[0008] The technical solution to achieve the above object is: a method for preparing thin samples from loose coal rock samples, characterized by comprising the following method steps: S1. Observe the cracks of coal block samples and confirm the bedding direction; S2. Wrap the coal block sample with a transparent heat shrinkable film and a transparent flexible plastic shell in sequence; S3, clamp the coal block sample wrapped in the transparent flexible plastic shell, and then cut the clamped coal rock sample along the bedding direction to obtain a thin sample block with a thickness of 3-4 cm and a length and width of not less than 4*4 cm; S4, removing the heat shrink film and the flexible glue shell on the surface of the thin sample, placing the thin sample in a glue boiling device, rolling in the first rosin glue at 100-120° C. for 2-5 minutes, taking it out, and cooling it to room temperature; S5, clamping and cutting the thin sample obtained in step S4 again along the bedding direction, so that the thin sample has one side exposed and parallel to the bedding direction; S6, placing the thin sample cut in step S5 in a glue boiling device, rolling it in the first rosin glue at 100-120° C. for 2-5 minutes, then taking it out and cooling it to room temperature; S7, clamping the thin sample block obtained in step S6, and then cutting 2-3 vertical planes in different directions along a direction perpendicular to the bedding direction, wherein the vertical planes respectively expose coal and rock samples; S8, placing the thin sample cut in step S7 in a glue boiling device, rolling it in the first rosin glue at 100-120° C. for 2-5 minutes, then taking it out and cooling it to room temperature; S9, placing the thin sample block in a glue boiling device, rolling it in the second rosin glue at 160-170° C. for 3-10 minutes, and then taking it out to obtain a block to be ground; S10, grinding the parallel surface and the vertical surface of the grinding block to be ground respectively to obtain a thin sample.

[0009] Furthermore, the specific method of wrapping the transparent heat shrinkable film and the transparent flexible plastic shell in step S2 is: 1) 1) Wrap the coal sample with a heat shrink film under hot air conditions; 2) Place the coal sample wrapped with the heat shrink film on the plasticine block, and press the coal sample downward so that the lower half of the coal sample is buried in the plasticine block; 3) Use a thin film to isolate the junction of the coal sample and the plasticine block; 4) Apply multiple layers of liquid silicone on the outer heat shrink film of the coal sample exposed from the plasticine block, the total thickness of the liquid silicone is not more than 0.5 cm, and during the application process, wait until the upper layer solidifies before applying the next layer; 5) Remove the applied liquid silicone after it is dry, then turn the coal sample over, and press the other half that has not been coated with liquid silicone into another plasticine block; 6) Repeat steps 3) and 4); 7) Remove the liquid silicone applied on the other side of the coal sample after it is dry to obtain a flexible plastic shell of the coal sample; 8) Trim the port of the flexible plastic shell to a flat surface, and then stick it to the transparent heat shrink film outside the coal sample with double-sided tape.

[0010] Furthermore, the clamping mechanism of the clamping process in steps 3), 5), and 7) includes a base, on which a manual first matrix needle flexible clamp is installed, the elastic needles of the first matrix needle flexible clamp are vertically upward, and a pneumatic clamp for clamping the coal block sample downward in cooperation with the first matrix needle flexible clamp is provided above the matrix needle flexible clamp, and the pneumatic clamp is fixed on the base; Two pneumatically controlled second matrix needle flexible clamps arranged opposite to each other are provided on the front and rear sides of the first matrix needle flexible clamp, and the second matrix needle flexible clamps cooperate with each other to clamp the coal block sample along the front and rear sides.

[0011] Furthermore, in steps 3), 5), and 7), the cutting process is performed by a wire cutting machine, and the cutting wire of the wire cutting machine is a molybdenum wire; in steps 4), 6), and 8), the first rosin glue includes rosin and turpentine, and the mass ratio of rosin to turpentine is 7:3; in step 9), the second rosin glue includes rosin and turpentine, and the mass ratio of rosin to turpentine is 3:2.

[0012] Furthermore, in step S10, the block to be ground first uses 200 mesh and 500 mesh sandpapers to remove the glue layer on the grinding surface, and then uses 1000 mesh, 2000 mesh, and 4000 mesh metallographic sandpapers to grind the sample layer on the grinding surface, and then uses 3 micron diamond polishing liquid and 1 micron alumina polishing liquid to fine-polish the grinding surface in sequence. After each grinding and fine-polishing process, it is cleaned with anhydrous alcohol and air-dried, and finally placed under a microscope for inspection and acceptance to obtain a thin sample.

[0013] Furthermore, the thickness of the coal rock sample after cutting in step S5 is not less than 3 cm.

[0014] Furthermore, the glue boiling equipment includes a frame on which a plurality of constant temperature oil bath pots are arranged, and barrel bodies for placing thin sample blocks are arranged above the constant temperature oil bath pots, and mesh holes are evenly distributed on the barrel bodies. A lifting and rotating drive mechanism for driving the corresponding barrel bodies to lift and rotate is installed on the frame.

[0015] Furthermore, the lifting and rotating drive mechanism includes a lifting drive cylinder, the telescopic end of the lifting drive cylinder is vertically upward and connected to a mounting seat, a vertically downward guide rod is installed at the bottom of the mounting seat, a guide sleeve is installed on the frame and slides with the guide rod, a driving motor is installed on the mounting seat, a horizontally arranged first transmission shaft is installed at the output end of the driving motor, a second transmission shaft is installed at the output end of the first transmission shaft and forms an angle of 130-150° with the first transmission shaft, the first transmission shaft and the second transmission shaft are connected by a universal joint, the first transmission shaft and the second transmission shaft are respectively rotatably mounted on the mounting seat through bearing seats, and the output end of the second transmission shaft is connected to a three-claw clamping cylinder for clamping the barrel body.

[0016] Furthermore, a circle of universal wheels for supporting the bottom of the constant temperature oil bath is arranged at the bottom of the barrel.

[0017] Furthermore, the three-jaw clamping cylinder is provided with three clamping jaws extending forward, the outer ends of the clamping jaws are bent inwards by 90° to form an L-shape, and the port of the barrel body is provided with an outer flange for facilitating the limiting of the position when the clamping jaws are clamped.

[0018] Beneficial effects of the present invention: When coating with glue, the coal and rock samples are driven by an inclined rotating barrel, so that the samples rotate when coated with glue, which promotes the penetration and absorption of glue into the cracks.

[0019] The glue wrapped in the low-temperature zone (the first rosin glue) mainly plays the role of forming an overall hard glue shell, preventing it from breaking again during the blade cutting process, consolidating the shape of the sample block throughout the process, and allowing the parallel cutting operation to proceed stably. The glue in the high-temperature zone (the second rosin glue) mainly has a penetrating effect to fill the fine cracks.

[0020] When the coal and rock samples are cut before being coated with glue, the outside is sequentially wrapped with a heat shrink film and a silicone layer, and combined with molybdenum wire cutting, vibration damage is greatly reduced, and sample fragmentation is avoided.

[0021] The heat shrinkable film of the invention plays an isolating role, preventing the liquid silica gel from directly contacting the sample block and contaminating the sample block; and the clamping force of the clamp is buffered by the large-area surrounding of the transparent flexible plastic shell.

[0022] The flexible clamp of the present invention is flexibly used, curved surface clamping, point clamping and fixing are accurate, and cutting stability is increased. The first matrix needle flexible clamp adopts a manual clamp to lay a foundation for stable clamping, and pneumatic clamps are adopted on the side and top to accurately monitor the clamping force.

[0023] The coal rock glue material currently used is a glue obtained by boiling rosin and turpentine in a certain ratio. It is a non-crystalline polymer with a softening range of about 70-80℃. It is basically in a flowable liquid state at 80-200℃, but the fluidity is different in different temperature ranges. According to long-term production practice observations, at 100-120℃, the viscosity is high (3000-4000mPa.s) and the glue is applied quickly. For the convenience of explanation, we customize it as "thick glue". After the overall wrapping, it increases a certain hardness and mechanical strength. After applying thick glue, the hardness can adapt to cutting under certain conditions.

[0024] When heated to 160-170℃, the viscosity drops significantly (the viscosity of thick glue can exceed 3000-4000mPa.s, and that of thin glue may be 300-500mPa.s). Defined as thin glue, the glue is obviously thin and thick, and has good fluidity. Under this temperature condition, the gaps between the glue and the coal interact with each other, the permeability of the fillings is greatly improved, and the gaps are filled in large quantities, laying the foundation for the subsequent grinding work.

[0025] The present invention sets the mass ratio of rosin to turpentine in the first rosin glue in the low temperature zone to 7:3, which has more rosin and higher viscosity, and can improve the wrapping effect.

[0026] In the present invention, the mass ratio of rosin to turpentine in the second rosin glue in the high temperature zone is 3:2, the turpentine is more, the viscosity is small, and the sample gap can be better penetrated.

[0027] The present invention greatly reduces sample fragmentation in preparation, does not waste limited samples, obtains accurate sample information, improves safety performance through equipment modification, improves work efficiency through method modification, and greatly improves operational convenience.

[0028] The sample prepared by the present invention is observed under a microscope and photographed. Various types of cracks have clear directions or features without any depressions or omissions. There are fewer cracks caused by external forces, which do not affect the calculation results of the sample, and the calculation results are highly accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the main view of the glue boiling equipment; Figure 2 It is a cross-sectional view of the glue boiling equipment; Figure 3 Schematic diagram of the state of applying liquid silica gel to a coal block sample; Figure 4 This is a schematic diagram of the cutting state of the wire cutting equipment and the flexible fixture. DETAILED DESCRIPTION

[0030] The present invention discloses a method for preparing a thin sample from a loose coal rock sample block, comprising the following steps: S1. Observe the cracks of coal block samples and confirm the bedding direction; S2. Wrap the coal block sample with a transparent heat shrinkable film and a transparent flexible plastic shell in sequence; S3. Clamp the coal block sample wrapped in the transparent flexible plastic shell, and then cut the clamped coal rock sample along the bedding direction to obtain a thin sample block with a thickness of 3-4 cm and a length and width of not less than 4*4 cm; S4, removing the heat shrink film and the flexible glue shell on the surface of the thin sample, placing the thin sample in a glue boiling device, rolling in the first rosin glue at 100-120° C. for 2-5 minutes, taking it out, and cooling it to room temperature; S5, clamping and cutting the thin sample obtained in step S4 again along the bedding direction, so that the thin sample has one side exposed and parallel to the bedding direction; S6, placing the thin sample cut in step S5 in a glue boiling device, rolling it in the first rosin glue at 100-120° C. for 2-5 minutes, then taking it out and cooling it to room temperature; S7, clamping the thin sample block obtained in step S6, and then cutting 2-3 vertical planes in different directions along a direction perpendicular to the bedding direction, wherein the vertical planes respectively expose coal and rock samples; S8, placing the thin sample cut in step S7 in a glue boiling device, rolling it in the first rosin glue at 100-120° C. for 2-5 minutes, then taking it out and cooling it to room temperature; S9, placing the thin sample block in a glue boiling device, rolling it in the second rosin glue at 160-170° C. for 3-8 minutes, and then taking it out to obtain a block to be ground; S10. The parallel surface and vertical surface of the grinding block are polished respectively. Specifically, the grinding block is firstly removed from the glue layer of the grinding surface with 200 mesh and 500 mesh sandpapers, and then the sample layer of the grinding surface is polished with 1000 mesh, 2000 mesh and 4000 mesh metallographic sandpapers, and then the grinding surface is finely polished with 3 micron diamond polishing liquid and 1 micron alumina polishing liquid, and after each grinding and fine polishing process, it is cleaned with anhydrous alcohol and air-dried, and finally placed under a microscope for inspection and acceptance to obtain a thin sample.

[0031] As a further illustration of this embodiment, Figure 3 As shown, the specific method of wrapping the transparent heat shrinkable film 20 and the transparent flexible plastic shell 21 in step S2 is: 1) attaching the heat shrinkable film 20 to the outside of the coal block sample 22 under hot air conditions; 2) placing the coal block sample 22 wrapped with the heat shrinkable film 20 on the plasticine block 23, and pressing the coal block sample 22 downward so that the lower half of the coal block sample 22 is buried in the plasticine block 23; 3) laying a plastic film 24 for isolation treatment at the junction of the coal block sample 22 and the plasticine block 23; 4) applying multiple layers of liquid silicone on the outer heat shrinkable film 20 of the coal block sample 22 exposed from the plasticine block 23, and the total thickness of the liquid silicone 21 is not more than 0.5c m, and in the process of applying, wait until the upper layer solidifies before applying the next layer; 5) remove the liquid silicone 21 to be applied after it dries, then turn the coal block sample 22 over, and press the other half that has not been coated with liquid silicone into another piece of plasticine; 6) repeat steps 3) and 4); 7) remove the liquid silicone applied on the other side of the coal block sample after it dries, and obtain a flexible plastic shell with the coal block sample; 8) trim the port of the flexible plastic shell to a flat surface, and then stick it to the transparent heat shrink film 20 outside the coal block sample 22 with double-sided tape.

[0032] As a further illustration of this embodiment, Figure 4 As shown, the clamping mechanism of the clamping process in steps 3), 5), and 7) includes a base 25, on which a manual first matrix needle flexible clamp 26 is installed, the elastic needles of the first matrix needle flexible clamp 26 are vertically upward, and a pneumatic clamp 27 for clamping the coal block sample downward in cooperation with the first matrix needle flexible clamp 26 is provided above the matrix needle flexible clamp 26. The pneumatic clamp 27 can specifically adopt a cylinder 30, and the telescopic end of the cylinder 30 is connected to an L-shaped clamp 31 with a clamp head facing downward, and the pneumatic clamp 27 is fixed on the base 25.

[0033] Two pneumatically controlled second matrix needle flexible clamps 28 are arranged relatively to each other on the front and rear sides of the first matrix needle flexible clamp 26. The elastic needles of the second matrix needle flexible clamp 28 are arranged relatively to each other. The second matrix needle flexible clamp 28 is driven by a displacement driving structure to approach to clamp or move away from to release the clamped thin sample block. It is an existing mature product and will not be elaborated here.

[0034] When the clamping mechanism is used, first confirm the bedding direction of the sample block, then place the sample block vertically on the first matrix needle flexible clamp 26 according to the bedding direction, and lock the sample position through the handle of the first matrix needle flexible clamp 26, then drive the pneumatic clamp 27 downward to cooperate with the first matrix needle flexible clamp 26 to clamp the coal block sample, and at the same time control the clamping pressure to avoid the coal block sample from breaking.

[0035] After the vertical holding force is stable, the second matrix needle flexible clamps 28 on both sides clamp the two side surfaces and control the clamping pressure to prevent the compacted coal block sample from breaking.

[0036] During the clamping process of the pneumatic clamp 27 and the second matrix needle flexible clamp 28, when the clamping pressure reaches 0.6 MPa, the pressure is adjusted step by step by 0.1 MPa. After each adjustment, the sample block is shaken until the sample block stops shaking, and the pressure adjustment is completed.

[0037] As a further illustration of this embodiment, the cut end of the clamped sample protrudes out of the clamping mechanism to facilitate cutting.

[0038] As the right end of this embodiment, the cutting process in steps 3), 5), and 7) uses a wire cutting machine 29 to cut the sample clamped by the clamping mechanism. The cutting wire of the wire cutting machine 29 uses molybdenum wire. Preferably, the wire cutting machine 29 is installed on the base 25 and is located on one side of the sample cutting end. Those skilled in the art can make a reasonable choice based on the existing molybdenum wire wire cutting machine, and the specific structure will not be repeated.

[0039] The first rosin glue comprises rosin and turpentine, and the mass ratio of rosin to turpentine is 7:3. The second rosin glue in step 9) comprises rosin and turpentine, and the mass ratio of rosin to turpentine is 3:2.

[0040] As a further illustration of this embodiment, Figure 1 , 2 As shown, the glue boiling equipment includes a frame 1, on which a plurality of constant temperature oil bath pots 2 are arranged, and above the constant temperature oil bath pots 2, barrel bodies 3 for placing thin sample blocks are arranged correspondingly, and a circle of universal wheels 17 for supporting the bottom of the constant temperature oil bath pot are arranged at the bottom of the barrel body 3.

[0041] The barrel body 3 is evenly distributed with mesh holes, and the frame 1 is equipped with a lifting and rotating driving mechanism 4 for driving the corresponding barrel body to lift and rotate.

[0042] The lifting and rotating drive mechanism 4 includes a lifting drive cylinder 5, the telescopic end of the lifting drive cylinder 5 is vertically upward and connected to a mounting seat 6, a vertically downward guide rod 7 is installed at the bottom of the mounting seat 6, a guide sleeve 8 is installed on the frame 1 and is slidingly matched with the guide rod 7, a drive motor 9 is installed on the mounting seat 6, a horizontally arranged first transmission shaft 10 is installed at the output end of the drive motor 9, and a second transmission shaft 1 forming an angle of 130-150° with the first transmission shaft 10 is installed at the output end of the first transmission shaft 10 1, the first transmission shaft 10 is connected to the second transmission shaft 11 through a universal joint 12, the first transmission shaft 10 and the second transmission shaft 11 are rotatably mounted on the mounting seat 6 through a bearing seat 13 respectively, the output end of the second transmission shaft 11 is connected to a three-claw clamping cylinder 14 for clamping the barrel body, the three-claw clamping cylinder 14 is provided with three forwardly extending clamping jaws 15, the outer ends of the clamping jaws 15 are bent inwardly 90° to form an L shape, and the port of the barrel body is provided with an outer flange 16 for limiting the position when the clamping jaws 15 are clamped.

[0043] When wrapping with glue, the sample is placed in the barrel body 3, and the lifting drive cylinder 5 drives the barrel body 3 downward into the constant temperature oil bath pot 2. The driving motor 9 drives the barrel body 3 to rotate, so that the sample is turned over in the constant temperature oil bath pot 2 to achieve glue wrapping of the sample. After the glue wrapping is completed, the lifting drive cylinder 5 drives the barrel body 3 upward to separate from the constant temperature oil bath pot 2.

Claims

1. A method for preparing thin samples from loose coal rock samples, characterized in that: The method comprises the following steps: S1. Observe the cracks of coal block samples and confirm the bedding direction; S2. Wrap the coal block sample with a transparent heat shrinkable film and a transparent flexible plastic shell in sequence; S3, clamp the coal block sample wrapped in the transparent flexible plastic shell, and then cut the clamped coal rock sample along the bedding direction to obtain a thin sample block with a thickness of 3-4 cm and a length and width of not less than 4*4 cm; S4, removing the heat shrink film and the flexible glue shell on the surface of the thin sample, placing the thin sample in a glue boiling device, rolling in the first rosin glue at 100-120° C. for 2-5 minutes, taking it out, and cooling it to room temperature; S5, clamping and cutting the thin sample obtained in step S4 again along the bedding direction, so that the thin sample has one side exposed and parallel to the bedding direction; S6, placing the thin sample cut in step S5 in a glue boiling device, rolling it in the first rosin glue at 100-120° C. for 2-5 minutes, then taking it out and cooling it to room temperature; S7, clamping the thin sample block obtained in step S6, and then cutting 2-3 vertical planes in different directions along a direction perpendicular to the bedding direction, wherein the vertical planes respectively expose coal and rock samples; S8, placing the thin sample cut in step S7 in a glue boiling device, rolling it in the first rosin glue at 100-120° C. for 2-5 minutes, then taking it out and cooling it to room temperature; S9, placing the thin sample block in a glue boiling device, rolling it in the second rosin glue at 160-170° C. for 3-10 minutes, and then taking it out to obtain a block to be ground; S10, grinding the parallel surface and the vertical surface of the grinding block to be ground respectively to obtain a thin sample.

2. The method for preparing thin specimens from loose coal rock specimens according to claim 1, characterized in that: The specific method of wrapping the transparent heat shrinkable film and the transparent flexible plastic shell in step S2 is: 1) attaching the heat shrinkable film to the outside of the coal block sample under hot air conditions; 2) placing the coal block sample wrapped with the heat shrinkable film on the plasticine block, and pressing the coal block sample downward so that the lower half of the coal block sample is buried in the plasticine block; 3) using a film to isolate the junction between the coal block sample and the plasticine block; 4) applying multiple layers of liquid silicone on the outer heat shrinkable film of the coal block sample exposed from the plasticine block, the total thickness of the liquid silicone is not more than 0.5 cm, and in the application process, wait for the upper layer to solidify before applying the next layer; 5) Remove the applied liquid silicone after it has dried, then turn the coal block sample over and press the other half that has not been coated with liquid silicone into another piece of plasticine; 6) Repeat steps 3) and 4); 7) Remove the liquid silicone applied on the other side of the coal block sample after it has dried to obtain a flexible plastic shell of the coal block sample; 8) Trim the port of the flexible plastic shell to a flat surface, and then stick it to the transparent heat shrink film outside the coal block sample with double-sided tape.

3. The method for preparing thin specimens from loose coal rock specimens according to claim 1, characterized in that: The clamping mechanism of the clamping process in steps 3), 5) and 7) includes a base, on which a manual first matrix needle flexible clamp is installed, the elastic needles of the first matrix needle flexible clamp are vertically upward, and a pneumatic clamp for clamping the coal block sample downward in cooperation with the first matrix needle flexible clamp is provided above the matrix needle flexible clamp, and the pneumatic clamp is fixed on the base; Two pneumatically controlled second matrix needle flexible clamps arranged opposite to each other are provided on the front and rear sides of the first matrix needle flexible clamp, and the second matrix needle flexible clamps cooperate with each other to clamp the coal block sample along the front and rear sides.

4. The method for preparing thin specimens from loose coal rock specimens according to claim 1, characterized in that: In steps 3), 5), and 7), the cutting process is performed by a wire cutting machine, and the cutting wire of the wire cutting machine is a molybdenum wire; in steps 4), 6), and 8), the first rosin glue includes rosin and turpentine, and the mass ratio of rosin to turpentine is 7:3; in step 9), the second rosin glue includes rosin and turpentine, and the mass ratio of rosin to turpentine is 3:

2.

5. The method for preparing thin specimens from loose coal rock specimens according to claim 1, characterized in that: In step S10, the block to be ground first uses 200 mesh and 500 mesh sandpaper to remove the glue layer on the grinding surface, and then uses 1000 mesh, 2000 mesh, and 4000 mesh metallographic sandpaper to grind the sample layer on the grinding surface. After that, 3 micron diamond polishing liquid and 1 micron alumina polishing liquid are used to fine-polish the grinding surface in sequence. After each grinding and fine-polishing process is completed, it is cleaned with anhydrous alcohol and air-dried, and finally placed under a microscope for inspection and acceptance to obtain a thin sample.

6. The method for preparing thin specimens from loose coal rock specimens according to claim 1, characterized in that: The thickness of the coal rock sample after cutting in step S5 is not less than 3 cm.

7. The method for preparing thin specimens from loose coal rock specimens according to claim 1, characterized in that: The glue boiling equipment includes a frame on which a plurality of constant temperature oil bath pots are arranged. Above the constant temperature oil bath pots, barrels for placing thin sample blocks are arranged correspondingly, and the barrels are evenly provided with mesh holes. A lifting and rotating driving mechanism for driving the corresponding barrels to lift and rotate is installed on the frame.

8. The method for preparing thin specimens from loose coal rock specimens according to claim 7, characterized in that: The lifting and rotating drive mechanism includes a lifting drive cylinder, the telescopic end of the lifting drive cylinder is vertically upward and connected to a mounting seat, a vertically downward guide rod is installed at the bottom of the mounting seat, a guide sleeve that slides with the guide rod is installed on the frame, a driving motor is installed on the mounting seat, a horizontally arranged first transmission shaft is installed on the output end of the driving motor, a second transmission shaft that forms an angle of 130-150° with the first transmission shaft is installed on the output end of the first transmission shaft, the first transmission shaft and the second transmission shaft are connected by a universal joint, the first transmission shaft and the second transmission shaft are rotatably installed on the mounting seat through bearing seats respectively, and the output end of the second transmission shaft is connected to a three-claw clamping cylinder for clamping the barrel body.

9. The method for preparing thin specimens from loose coal rock specimens according to claim 5, characterized in that: The bottom of the barrel body is provided with a circle of universal wheels for supporting the bottom of the constant temperature oil bath pot.

10. The method for preparing thin specimens from loose coal rock specimens according to claim 5, characterized in that: The three-jaw clamping cylinder is provided with three clamping jaws extending forward, the outer ends of the clamping jaws are bent inwards by 90 degrees to form an L shape, and the port of the barrel body is provided with an outer flange for facilitating the limiting of the position when the clamping jaws are clamped.

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