A method for preparing thin samples from a bulk coal or rock sample

Abstract

A method for preparing a thin sample piece of loose coal rock sample block relates to the technical field of coal rock sample rubberizing. The method steps are as follows: S1, observing the crack of the coal sample block; S2, wrapping the coal sample block with a heat-shrinkable film and a flexible glue shell; S3, clamping and cutting the wrapped coal sample block to obtain a thin sample block; S4, removing the heat-shrinkable film and the flexible glue shell, and placing the thin sample block in a glue boiling device for rubberizing; S5, clamping and cutting the thin sample block along the bedding direction; S6, placing the thin sample block in the glue boiling device for rubberizing; S7, cutting 2-3 vertical planes perpendicular to the bedding direction, and exposing the coal rock sample on the vertical planes; S8, placing the thin sample block in the glue boiling device for rubberizing; S9, placing the ground thin sample block in the glue boiling device for rubberizing; and S10, polishing to obtain a thin sample block. When the coal rock sample is cut before rubberizing, the outside is sequentially wrapped with a heat-shrinkable film and a silica gel layer, and combined with molybdenum wire cutting, the vibration damage is greatly reduced, and sample fragmentation is avoided.

Description

Technical Field

[0001] This invention relates to the field of adhesive coating technology for coal and rock samples, specifically a method for preparing thin sample sheets from loose coal and rock samples. Background Technology

[0002] We tailor cutting, glue-boiling, and grinding solutions to the specific characteristics of fragile coal blocks.

[0003] This research addresses the real-world challenges of coal and rock cutting. During on-site extraction, the coal and rock samples are repeatedly subjected to external forces, resulting in multiple cracks and damages. These are not natural samples, but the inherent fragility of coal and rock, combined with the external environment, makes the fragmentation extremely complex and difficult to control. The aim is to buffer and mitigate these issues, minimizing fragmentation damage. However, rigorous conditional experiments are necessary for compressive strength, tensile strength, and hardness testing of coal and rock. In actual production, the number of extracted coal and rock samples is limited, while the required coal and rock analysis projects are numerous. Therefore, conducting conditional experiments on individual samples for relevant mechanical tests is neither feasible nor necessary.

[0004] The current coal cutting method has problems and needs improvement. There are no suitable clamps for holding and cutting irregular coal blocks of approximately 10x10x10cm to 15x15x15cm. Cutting is primarily done with single-blade cutters, which are inadequate for cutting fragile natural coal and rock samples (brittle, easily broken, and easily damaged). In actual production, coal and rock samples collected from the field need to undergo various analytical tests. However, due to limited mining conditions, the number of samples obtained is limited. Repeated use of ordinary single-blade cutters to obtain the required samples is common. Generally, the cutting tool vibrates excessively, and the inherent permeability and brittleness of coal, along with its numerous cracks, makes it prone to breakage and prevents the acquisition of whole samples. Especially for rock and mineral analysis, sampling from locations containing specific geological information is often necessary to minimize sample loss and damage. Solving these production problems has become a critical and urgent issue.

[0005] In the existing technology, the coal and rock boiling method is relatively outdated, the equipment is outdated, and the boiling process is simple and crude. It needs to be optimized, and both should be carried out simultaneously.

[0006] When coating the samples with adhesive, the pot for boiling the adhesive is placed on a heating plate with an electric heating wire and heated until it reaches a fluid state. Then, the coal and rock samples are held in the pot by clamps and rolled to coat them with adhesive. This method has obvious defects in actual operation.

[0007] 1) When the adhesive is heated to a high temperature, it is easy to spray onto the edge or outside of the heating plate. The equipment is rudimentary and the operation is unsafe.

[0008] 2) Because the heating is done from the bottom of the pot to the top, the temperature is uneven. The glue on the upper edge of the pot has solidified. The inconsistent boiling temperature of the glue in the upper, middle and lower parts of the pot leads to inconsistent glue viscosity, which causes more air to be mixed into the pot and produces a lot of bubbles, affecting the glue boiling effect of the coal.

[0009] 3) Moreover, the amount of glue contained in a single container is relatively large. In a large and uneven heating environment, the glue is easily broken or even exploded due to thermal expansion and contraction.

[0010] 4) The glue boiling equipment is difficult to maintain a constant temperature, and it is practically impossible to implement constant temperature control conditions, so it is impossible to achieve accurate and reasonable use and boiling of rosin and turpentine.

[0011] 5) Traditional methods require a long boiling time, more than half an hour. The current method of boiling glue in different temperature zones greatly shortens the boiling time and improves the efficiency of glue boiling.

[0012] 6) Boiling the gel in a single container can cause the samples to mix and easily contaminate the samples.

[0013] In actual production, the heating of coal blocks also has certain limitations. Precise and effective temperature control has a significant impact on the glue-boiling effect of coal blocks. The glue-boiling ratio, temperature, air, viscosity changes, time, and movement mode all severely restrict the penetration and filling effect of the glue. Often, after the glue has dried, many air bubbles are visible on the surface or inside the glue layer. This results in the thin sample block not being tightly wrapped after glue-boiling, affecting the cutting hardness and polishing hardness of the sample block (cracking, fragmentation, surface depressions, etc.). These problems are caused by various defects in glue-boiling, equipment, heating conditions, and implementation. Therefore, the optimization and improvement of the glue-boiling method, as well as the modification of equipment and process flow, must be carried out simultaneously. Summary of the Invention

[0014] The purpose of this invention is to provide a method for preparing thin sections from loose coal and rock samples, which can effectively solve the problems in the background art.

[0015] The technical solution to achieve the above objective is: a method for preparing thin sections from loose coal and rock samples, characterized by comprising the following steps:

[0016] S1. Observe the cracks in the coal sample and confirm the direction of bedding;

[0017] S2. Wrap a transparent heat-shrink film and a transparent flexible plastic shell around the coal sample in sequence.

[0018] S3. Clamp the coal sample wrapped in a transparent flexible shell, and then cut the clamped coal 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.

[0019] S4. Remove the heat-shrink film and flexible shell from the surface of the thin sample block. Place the thin sample block in the glue boiling equipment and roll it in the first rosin glue at 100-120℃ for 2-5 minutes. Then remove it and cool it to room temperature.

[0020] S5. The thin sample block obtained in step S4 is clamped and cut along the bedding direction so that the thin sample block has one side exposed and a parallel surface that is parallel to the bedding direction.

[0021] S6. Place the thin sample block cut in step S5 into the glue boiling equipment, roll it in the first rosin glue at 100-120℃ for 2-5 minutes, and then take it out and cool it to room temperature.

[0022] S7. Clamp the thin sample block obtained in step S6, and then cut 2-3 vertical surfaces in different directions along the direction perpendicular to the bedding direction, exposing the coal and rock sample on each vertical surface.

[0023] S8. Place the thin sample block cut in step S7 into the glue boiling equipment, roll it in the first rosin glue at 100-120℃ for 2-5 minutes, and then take it out and cool it to room temperature.

[0024] S9. Place the thin sample block in the glue boiling equipment, roll it in the second rosin glue at 160-170℃ for 3-10 minutes, and then take it out to obtain the block to be ground.

[0025] S10. Grind the parallel and perpendicular surfaces of the sample to be ground to obtain a thin sample.

[0026] Furthermore, the specific method for wrapping the transparent heat-shrink film and the transparent flexible shell in step S2 is as follows: 1) 1) Apply heat-shrinkable film to the outside of the coal sample under hot air conditions; 2) Place the coal sample wrapped in heat-shrinkable film on a clay block and press it down so that the lower half of the coal sample is buried in the clay block; 3) Use a thin film to isolate the coal sample and the clay block at the junction; 4) Apply multiple layers of liquid silicone to the outer heat-shrinkable film of the coal sample that is exposed from the clay block. The total thickness of the liquid silicone should not exceed 0.5 cm, and the next layer should be applied only after the upper layer has solidified; 5) Remove the liquid silicone after it has dried, then turn the coal sample over and press the other half that has not been coated with liquid silicone into another clay block; 6) Repeat steps 3) and 4); 7) Remove the liquid silicone after it has dried on the other side of the coal sample to obtain a flexible shell of the coal sample; 8) Trim and cut the ends of the flexible shell to a flat surface, and then attach it to the transparent heat-shrinkable film on the outside of the coal sample with double-sided tape.

[0027] Further, the clamping mechanism in the clamping process of 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. Above the matrix needle flexible clamp, a pneumatic clamp is provided for clamping the coal sample downward in conjunction with the first matrix needle flexible clamp. The pneumatic clamp is fixed on the base.

[0028] The first matrix needle flexible clamp has two pneumatically controlled second matrix needle flexible clamps arranged opposite each other on its front and rear sides. The second matrix needle flexible clamps cooperate with each other to clamp the coal block sample along the front and rear sides.

[0029] Furthermore, in steps 3), 5), and 7), the cutting process is carried out using a wire cutting machine, and the cutting wire of the wire cutting machine is molybdenum wire; in steps 4), 6), and 8), the first rosin adhesive includes rosin and turpentine oil, with a mass ratio of rosin to turpentine oil of 7:3; in step 9), the second rosin adhesive includes rosin and turpentine oil, with a mass ratio of rosin to turpentine oil of 3:2.

[0030] Further, in step S10, the sample block to be ground is first removed from the adhesive layer of the grinding surface by 200-grit and 500-grit sandpaper in sequence, and then the sample layer of the grinding surface is ground by 1000-grit, 2000-grit and 4000-grit metallographic sandpaper in sequence. After that, the grinding surface is finely polished by 3-micron diamond polishing liquid and 1-micron alumina polishing liquid in sequence. After each grinding and fine polishing process, it is cleaned with anhydrous alcohol and air-dried. Finally, it is placed under a microscope for inspection and acceptance to obtain a thin sample block.

[0031] Furthermore, the thickness of the coal and rock sample after cutting in step S5 shall not be less than 3 cm.

[0032] Furthermore, the glue boiling equipment includes a frame, on which multiple constant temperature oil baths are arranged. Above each constant temperature oil bath is a corresponding barrel for placing thin sample blocks. The barrels are evenly distributed with mesh holes. The frame is equipped with a lifting and rotating drive mechanism for driving the corresponding barrels to lift and rotate.

[0033] 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 base. A vertically downward guide rod is installed at the bottom of the mounting base. A guide sleeve that slides and guides the guide rod is installed on the frame. A drive motor is installed on the mounting base. A horizontally arranged first drive shaft is installed at the output end of the drive motor. A second drive shaft forming an angle of 130-150° with the first drive shaft is installed at the output end of the first drive shaft. The first drive shaft and the second drive shaft are connected by a universal joint. The first drive shaft and the second drive shaft are rotatably mounted on the mounting base through bearing seats. A three-jaw clamping cylinder for clamping the barrel is connected to the output end of the second drive shaft.

[0034] Furthermore, the bottom of the barrel is provided with a ring of casters for support on the bottom of the constant temperature oil bath.

[0035] Furthermore, the three-jaw clamping cylinder is equipped with three forward-extending jaws, the outer ends of which are bent inward at 90° to form an L-shape, and the port of the barrel is provided with an outward-facing flange to facilitate the clamping of the jaws.

[0036] The beneficial effects of this invention are:

[0037] During the coating process, a tilted and rotating barrel is used to rotate the coal and rock sample, causing the sample to rotate while being coated with adhesive, which promotes the penetration and absorption of adhesive into the cracks.

[0038] The adhesive in the low-temperature zone (first rosin adhesive) mainly serves to form a relatively hard overall shell, preventing further breakage during blade cutting and consolidating the shape of the sample throughout the process, ensuring stable parallel cutting operations. The adhesive in the high-temperature zone (second rosin adhesive) mainly functions to penetrate and fill the fine cracks.

[0039] In this invention, when coal and rock samples are cut before being coated with adhesive, the outside is wrapped with heat-shrink film and silicone layer in sequence, and combined with molybdenum wire cutting, vibration damage is greatly reduced, and sample breakage is avoided.

[0040] The heat-shrink film of this invention acts as an isolation layer to prevent liquid silicone from directly contacting and contaminating the sample; the large-area encapsulation by the transparent flexible shell buffers the clamping force of the fixture.

[0041] The flexible clamp of this invention utilizes curved surface clamping and point clamping for accurate positioning, increasing cutting stability. The first matrix needle flexible clamp is a manual clamp, laying a stable foundation for clamping, while pneumatic clamps are used on the sides and top to accurately monitor the clamping force.

[0042] The currently used coal-fired adhesive material is a glue made by boiling rosin and turpentine in a certain proportion. It is an amorphous polymer with a softening range of about 70-80℃. It is basically a flowable liquid at 80-200℃, but its fluidity varies in different temperature ranges. Based on long-term production practice and observation, it is known that at 100-120℃, the viscosity is high (3000-4000 mPa.s), and the adhesive adheres quickly. For ease of explanation, we define it as "thick glue". After overall coating, it increases a certain degree of hardness and mechanical strength. After applying thick glue, the hardness can adapt to cutting under certain conditions.

[0043] When heated to 160-170℃, the viscosity drops significantly (the viscosity of thick glue can exceed 3000-4000 mPa·s, while that of thin glue may be only 300-500 mPa·s). It is defined as thin glue, which is significantly thinner and more viscous, with good fluidity. Under these temperature conditions, the glue and coal interact with each other, greatly improving the filling permeability and filling the gaps, thus laying the foundation for the subsequent grinding work.

[0044] In this invention, the mass ratio of rosin to turpentine in the first rosin adhesive in the low-temperature zone is set to 7:3. The higher rosin content and viscosity can improve the coating effect.

[0045] In this invention, the mass ratio of rosin to turpentine in the second rosin resin in the high-temperature zone is 3:2. The higher turpentine content results in lower viscosity, allowing for better penetration into the sample gaps.

[0046] This invention significantly reduces sample breakage during preparation, avoids wasting limited samples, ensures accurate sample block information, improves safety performance through equipment modifications, enhances work efficiency through method modifications, and greatly improves operational convenience.

[0047] The samples prepared by this invention are observed and photographed under a microscope. The direction or characteristics of various types of cracks are clear, and there are no depressions or missing parts. There are few cracks caused by external forces, which do not affect the sample calculation results, and the calculation results are highly accurate. Attached Figure Description

[0048] Figure 1 This is a front view of the glue-cooking equipment;

[0049] Figure 2 This is a cross-sectional view of the glue-boiling equipment;

[0050] Figure 3 A schematic diagram showing the state of applying liquid silica gel to a coal sample.

[0051] Figure 4 This is a schematic diagram of the wire EDM equipment in operation with a flexible fixture. Detailed Implementation

[0052] This invention discloses a method for preparing thin sections from loose coal and rock samples, comprising the following steps:

[0053] S1. Observe the cracks in the coal sample and confirm the direction of bedding;

[0054] S2. Wrap a transparent heat-shrink film and a transparent flexible plastic shell around the coal sample in sequence.

[0055] S3. Clamp the coal sample wrapped in a transparent flexible shell, and then cut the clamped coal 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.

[0056] S4. Remove the heat-shrink film and flexible shell from the surface of the thin sample block. Place the thin sample block in the glue boiling equipment and roll it in the first rosin glue at 100-120℃ for 2-5 minutes. Then remove it and cool it to room temperature.

[0057] S5. The thin sample block obtained in step S4 is clamped and cut along the bedding direction so that the thin sample block has one side exposed and a parallel surface that is parallel to the bedding direction.

[0058] S6. Place the thin sample block cut in step S5 into the glue boiling equipment, roll it in the first rosin glue at 100-120℃ for 2-5 minutes, and then take it out and cool it to room temperature.

[0059] S7. Clamp the thin sample block obtained in step S6, and then cut 2-3 vertical surfaces in different directions along the direction perpendicular to the bedding direction, exposing the coal and rock sample on each vertical surface.

[0060] S8. Place the thin sample block cut in step S7 into the glue boiling equipment, roll it in the first rosin glue at 100-120℃ for 2-5 minutes, and then take it out and cool it to room temperature.

[0061] S9. Place the thin sample block in the glue boiling equipment, roll it in the second rosin glue at 160-170℃ for 3-8 minutes, and then take it out to obtain the block to be ground.

[0062] S10. Grind the parallel and perpendicular surfaces of the sample block to be ground. Specifically, first, use 200-grit and 500-grit sandpaper to remove the adhesive layer on the grinding surface, then use 1000-grit, 2000-grit, and 4000-grit metallographic sandpaper to grind the sample layer on the grinding surface. After that, use 3-micron diamond polishing liquid and 1-micron alumina polishing liquid to polish the grinding surface in sequence. After each grinding and fine polishing process, clean with anhydrous alcohol and air dry. Finally, place it under a microscope for inspection and acceptance to obtain a thin sample block.

[0063] As a further explanation of this embodiment, such as Figure 3As shown, the specific method for wrapping the transparent heat-shrink film 20 and the transparent flexible shell 21 in step S2 is as follows: 1) Apply the heat-shrink film 20 to the outside of the coal sample 22 under hot air conditions; 2) Place the coal sample 22 wrapped with the heat-shrink film 20 on the clay block 23 and press the coal sample 22 downwards so that the lower half of the coal sample 22 is buried in the clay block 23; 3) Use a plastic film 24 to isolate the coal sample 22 and the clay block 23 at the junction; 4) Apply multiple layers of liquid silicone to the outer heat-shrink film 20 of the coal sample 22 that is exposed on the clay block 23, with the total thickness of the liquid silicone 21 not exceeding 0.5 cm. m, and during the application process, wait for the upper layer to solidify before applying the next layer; 5) After the applied liquid silicone 21 has dried, remove it, then turn the coal sample 22 over and press the other half that has not been coated with liquid silicone into another piece of clay; 6) Repeat steps 3), 4); 7) After the liquid silicone applied to the other side of the coal sample has dried, remove it to obtain a flexible shell with the coal sample; 8) Trim and cut the ends of the flexible shell to a flat surface, and then attach it to the transparent heat shrink film 20 outside the coal sample 22 with double-sided tape.

[0064] As a further explanation of this embodiment, such as Figure 4 As shown, the clamping mechanism in steps 3), 5), and 7) includes a base 25. A manual first matrix needle flexible clamp 26 is installed on the base 25. The elastic needles of the first matrix needle flexible clamp 26 are vertically upward. A pneumatic clamp 27 is provided above the matrix needle flexible clamp 26 to clamp the coal sample downward in conjunction with the first matrix needle flexible clamp 26. Specifically, the pneumatic clamp 27 can be a cylinder 30. The telescopic end of the cylinder 30 is connected to an L-shaped clamp 31 with the clamp head facing downward. The pneumatic clamp 27 is fixed on the base 25.

[0065] The first matrix needle flexible clamp 26 has two pneumatically controlled second matrix needle flexible clamps 28 arranged opposite to each other on its front and rear sides. The elastic needles of the second matrix needle flexible clamps 28 are arranged opposite to each other. The second matrix needle flexible clamps 28 are driven to move closer to clamp or move away from the clamped thin sample block through a displacement drive structure. This is an existing mature product and will not be described in detail here.

[0066] When using the clamping mechanism, first confirm the stratification direction of the sample block, then place the sample block vertically on the first matrix needle flexible clamp 26 according to the stratification direction, and lock the sample position by 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 sample, while controlling the clamping pressure to prevent the coal sample from breaking.

[0067] After the vertical clamping force stabilizes, the flexible clamps of the second matrix pins on both sides clamp the two sides, while controlling the clamping pressure to prevent the coal block sample from breaking.

[0068] 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 in increments of 0.1 MPa. After each adjustment, the sample block is shaken until the sample block stops shaking, and the pressure adjustment is completed.

[0069] As a further explanation of this embodiment, the sample cutting end protrudes from the clamping mechanism after clamping to facilitate cutting.

[0070] As the right end of this embodiment, in steps 3), 5), and 7), the cutting process uses a wire cutting machine 29 to cut the sample held by the clamping mechanism. The cutting wire of the wire cutting machine 29 is a molybdenum wire. Preferably, the wire cutting machine 29 is mounted on the base 25 and located on one side of the sample cutting end. Those skilled in the art can make a reasonable selection based on existing molybdenum wire cutting machines. The specific structure will not be described in detail.

[0071] The first rosin glue includes rosin and turpentine, with a mass ratio of 7:3 for rosin and turpentine. The second rosin glue in step 9) includes rosin and turpentine, with a mass ratio of 3:2 for rosin and turpentine.

[0072] As a further explanation of this embodiment, such as Figure 1 , 2 As shown, the glue boiling equipment includes a frame 1, on which multiple constant temperature oil baths 2 are arranged. Above each constant temperature oil bath 2, a barrel 3 for placing thin sample blocks is arranged. The bottom of the barrel 3 is provided with a ring of casters 17 for supporting the bottom of the constant temperature oil bath.

[0073] The barrel body 3 is evenly distributed with mesh holes, and the frame 1 is equipped with a lifting and rotating drive mechanism 4 that drives the corresponding barrel body to lift and rotate.

[0074] 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 base 6. A vertically downward guide rod 7 is installed at the bottom of the mounting base 6. A guide sleeve 8 that slides and guides the guide rod 7 is installed on the frame 1. A drive motor 9 is installed on the mounting base 6. A horizontally arranged first transmission shaft 10 is installed at the output end of the drive motor 9. A second transmission shaft 10 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 drive shaft 10 and the second drive shaft 11 are connected by a universal joint 12. The first drive shaft 10 and the second drive shaft 11 are rotatably mounted on the mounting base 6 through bearing seats 13. The output end of the second drive shaft 11 is connected to a three-jaw clamping cylinder 14 for clamping the barrel. The three-jaw clamping cylinder 14 is provided with three forward-extending jaws 15. The outer ends of the jaws 15 are bent inward at 90° to form an L-shape. The port of the barrel is provided with an outer flange 16 to facilitate the clamping of the jaws 15.

[0075] During the coating process, the sample is placed inside the barrel 3. The lifting drive cylinder 5 drives the barrel 3 downward into the constant temperature oil bath 2, and the drive motor 9 drives the barrel 3 to rotate, so that the sample is flipped in the constant temperature oil bath 2 to achieve the coating. After the coating is completed, the lifting drive cylinder 5 drives the barrel 3 upward to detach from the constant temperature oil bath 2.

Claims

1. A method for preparing thin sections from loose coal and rock samples, characterized in that, The methods and steps include the following: S1. Observe the cracks in the coal sample and confirm the direction of bedding; S2. Wrap a transparent heat-shrink film and a transparent flexible plastic shell around the coal sample in sequence. S3. Clamp the coal sample wrapped in a transparent flexible shell, and then cut the clamped coal 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. Remove the heat-shrink film and flexible shell from the surface of the thin sample block. Place the thin sample block in the glue boiling equipment and roll it in the first rosin glue at 100-120℃ for 2-5 minutes. Then remove it and cool it to room temperature. S5. The thin sample block obtained in step S4 is clamped and cut along the bedding direction so that the thin sample block has one side exposed and a parallel surface that is parallel to the bedding direction. S6. Place the thin sample block cut in step S5 into the glue boiling equipment, roll it in the first rosin glue at 100-120℃ for 2-5 minutes, and then take it out and cool it to room temperature. S7. Clamp the thin sample block obtained in step S6, and then cut 2-3 vertical surfaces in different directions along the direction perpendicular to the bedding direction, exposing the coal and rock sample on each vertical surface. S8. Place the thin sample block cut in step S7 into the glue boiling equipment, roll it in the first rosin glue at 100-120℃ for 2-5 minutes, and then take it out and cool it to room temperature. S9. Place the thin sample block in the glue boiling equipment, roll it in the second rosin glue at 160-170℃ for 3-10 minutes, and then take it out to obtain the block to be ground. S10. Grind the parallel and perpendicular surfaces of the sample to be ground to obtain a thin sample. In steps S4, S6, and S8, the first rosin gum includes rosin and turpentine, with a mass ratio of 7:3 for rosin and turpentine. In step S9, the second rosin gum includes rosin and turpentine, with a mass ratio of 3:2 for rosin and turpentine. The glue boiling equipment includes a frame with multiple constant temperature oil baths on it. Above each constant temperature oil bath is a barrel for placing thin sample blocks. The barrels are evenly distributed with mesh holes. The frame is equipped with a lifting and rotating drive mechanism to drive the corresponding barrels to lift and rotate. 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 base. A vertically downward guide rod is installed at the bottom of the mounting base. A guide sleeve that slides and guides the guide rod is installed on the frame. A drive motor is installed on the mounting base. A horizontally arranged first drive shaft is installed at the output end of the drive motor. A second drive shaft forming a 130-150° angle with the first drive shaft is installed at the output end of the first drive shaft. The first drive shaft and the second drive shaft are connected by a universal joint. The first drive shaft and the second drive shaft are rotatably mounted on the mounting base through bearing seats. A three-jaw clamping cylinder for gripping the barrel is connected to the output end of the second drive shaft.

2. The method for preparing thin sections from loose coal and rock samples according to claim 1, characterized in that: The specific method for wrapping the transparent heat-shrink film and transparent flexible shell in step S2 is as follows: 1) Attach the heat-shrink film to the outside of the coal sample under hot air conditions; 2) Place the coal sample wrapped with the heat-shrink film on the clay block and press the coal sample downwards so that the lower half of the coal sample is buried in the clay block; 3) Use a thin film to isolate the coal sample and the clay block at the junction; 4) Apply multiple layers of liquid silicone to the outer heat-shrink film of the coal sample that is exposed from the clay block. The total thickness of the liquid silicone is not greater than 0.5cm, and the next layer is applied only after the upper layer has solidified. 5) After the applied liquid silicone has dried, remove it. Then, turn the coal sample over and press the other half, which has not been coated with liquid silicone, into another piece of modeling clay. 6) Repeat steps 3) and 4). 7) After the liquid silicone applied to the other side of the coal sample has dried, remove it to obtain a flexible shell for the coal sample. 8) Trim and cut the ends of the flexible shell to a flat surface, and then attach it to the transparent heat-shrink film on the outside of the coal sample with double-sided tape.

3. The method for preparing thin sections from loose coal and rock samples according to claim 1, characterized in that: The clamping mechanism in steps S3, S5, and S7 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. Above the matrix needle flexible clamp, a pneumatic clamp is provided for clamping the coal sample downward in conjunction with the first matrix needle flexible clamp. The pneumatic clamp is fixed on the base. The first matrix needle flexible clamp has two pneumatically controlled second matrix needle flexible clamps arranged opposite each other on its front and rear sides. 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 sections from loose coal and rock samples according to claim 1, characterized in that: In steps S3, S5, and S7, the cutting process is carried out using a wire EDM machine, and the cutting wire of the wire EDM machine is molybdenum wire.

5. The method for preparing thin sections from loose coal and rock samples according to claim 1, characterized in that: In step S10, the sample block to be ground is first removed from the adhesive layer of the grinding surface using 200-grit and 500-grit sandpaper in sequence. Then, the sample layer of the grinding surface is ground using 1000-grit, 2000-grit, and 4000-grit metallographic sandpaper in sequence. After that, the grinding surface is finely polished using 3-micron diamond polishing liquid and 1-micron alumina polishing liquid in sequence. After each grinding and fine polishing process, the sample block is cleaned with anhydrous alcohol and air-dried. Finally, the sample block is placed under a microscope for inspection and acceptance to obtain a thin sample block.

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

7. The method for preparing thin sections from loose coal and rock samples according to claim 1, characterized in that: The bottom of the barrel is equipped with a ring of casters for support on the bottom of the constant temperature oil bath.

8. The method for preparing thin sections from loose coal and rock samples according to claim 1, characterized in that: The three-jaw clamping cylinder is equipped with three forward-extending jaws, the outer ends of which are bent inward at 90° to form an L-shape. The port of the barrel is provided with an outward-facing flange to facilitate the clamping jaws to make positioning.

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