An ultra-clean coal preparation device

Abstract

The application discloses a super-clean coal preparation device, relates to the coal grinding technical field, and is used for preparing super-clean coal. In view of the problem that material deposition and pipeline blockage are prone to occur in the preparation of super-clean coal due to material characteristics, the super-clean coal preparation device is provided. A three-way pipe is arranged at a pipeline connected between a feeding pump and a sand mill, so that an external return pipeline can be connected. The other end of the return pipeline is connected to a lifting disperser. In this way, when the super-clean coal preparation process is just started, even if the rotating speed of the feeding pump is too large, the pulse in the pipeline is too large, and the material can return to the lifting disperser along the return pipeline, so that overpressure of the feeding pump and the pipeline is avoided, and material deposition is also avoided. Meanwhile, since the other end of the return pipeline is connected to the lifting disperser, the material returned to the lifting disperser is not wasted and can still be conveyed to the sand mill by the feeding pump for grinding.

Description

Technical Field

[0001] This application relates to the field of coal grinding technology, and in particular to an ultra-clean coal production device. Background Technology

[0002] Sand mills have significant advantages such as high production efficiency, low energy consumption, and continuous production capability, and are widely used in industries such as coatings and pesticides. Therefore, sand mills are also currently used in the production of ultra-clean coal.

[0003] Ultra-clean coal is clean coal with an ash content of less than 1% after chemical treatment. It can be used as an alternative energy source in power generation and on ships to replace heavy diesel oil. Due to the grinding requirements of ultra-clean coal, horizontal sand mills can continuously grind and disperse solid particles in liquids, are suitable for various operating methods, have high output, and the grinding media are evenly distributed throughout the grinding cylinder. Therefore, horizontal sand mills are used to grind ultra-clean coal. However, horizontal sand mills are more effective at grinding relatively uniform materials that are not prone to sedimentation, such as coatings. Ultra-clean coal slurry, on the other hand, is prone to sedimentation during material transportation, and material deposits in pipelines can easily cause blockages, hindering production.

[0004] Therefore, those skilled in the art urgently need an ultra-clean coal production device to solve the problem that material sedimentation and subsequent pipe blockage are common in ultra-clean coal production due to material properties. Summary of the Invention

[0005] The purpose of this application is to provide an ultra-clean coal production device to solve the problem that material sedimentation and subsequent pipe blockage are common in the current production of ultra-clean coal due to the material properties.

[0006] To solve the above-mentioned technical problems, this application provides an ultra-clean coal production device, characterized in that it includes: a lifting disperser 1, a feeding pump 2, a sand mill 3, a low-speed mixer 4, a pipeline 5, a tee 6, and a return pipeline 7;

[0007] The feed pump 2 is connected to the feed inlets of the lifting disperser 1 and the sand mill 3 through a pipe 5, which is used to transport the material initially crushed by the lifting disperser 1 to the sand mill 3 for further grinding.

[0008] The discharge port of the sand mill 3 is connected to the low-speed mixer 4 through a pipe 5, which is used to transport the ground material to the low-speed mixer 4 for mixing.

[0009] The tee 6 is located at the pipe 5 connecting the feed pump 2 and the inlet of the sand mill 3, and is used to connect one end of the return pipe 7. The other end of the return pipe 7 is connected to the lifting disperser 1.

[0010] Preferably, the return pipe 7 is composed of multiple pipe sections 5, wherein the pipe 5 connected to the tee 6 in the return pipe 7 is arranged vertically upward.

[0011] Preferably, the feed pump 2 is a hose pump.

[0012] Preferably, a pressure buffer tank 8 is provided at the outlet of the feed pump 2.

[0013] Preferably, a check valve 9 is provided at the feed inlet of the sand mill 3.

[0014] Preferably, the check valve 9 is a swing check valve.

[0015] Preferably, check valve 9 is a horizontal check valve.

[0016] Preferably, metal hoses 10 are provided at the inlet and outlet of the sand mill 3.

[0017] Preferably, the flow rate of the hose pump is 0.6 cubic meters per hour.

[0018] Preferably, the annular gap between the moving and stationary rings of the sand mill 3 is 1 mm.

[0019] This application provides an ultra-clean coal production device. By installing a T-junction at the connection point between the feed pump and the sand mill, an external return pipeline can be connected. The other end of the return pipeline is connected to a lifting disperser. Thus, at the very beginning of the ultra-clean coal production process, even if the feed pump's speed is too high, causing excessive pulses in the pipeline, the material can still return to the lifting disperser via the return pipeline, preventing overpressure in the feed pump and pipeline, and avoiding material sedimentation. Simultaneously, since the other end of the return pipeline is connected to the lifting disperser, which in turn supplies material to the feed pump, the material returning to the lifting disperser is not wasted and can still be transported by the feed pump to the sand mill for grinding later. Attached Figure Description

[0020] To more clearly illustrate the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a structural diagram of an ultra-clean coal production device provided by the present invention.

[0022] Among them, 1 is the lifting disperser, 2 is the feed pump, 3 is the sand mill, 4 is the low-speed mixer, 5 is the pipeline, 6 is the tee, 7 is the return pipeline, 8 is the pressure buffer tank, 9 is the check valve, and 10 is the metal hose. Detailed Implementation

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.

[0024] The core of this application is to provide an ultra-clean coal production device.

[0025] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] In recent years, with the rapid development of materials science, the demand for fine materials in various industries has been increasing. Dry grinding has specific particle size requirements for dry classification, presenting insurmountable technical obstacles. Mills cannot utilize very fine grinding media, hindering their ability to overcome inherent limitations such as the high strength of small particles, mineral agglomeration after fine grinding, and heat loss during grinding, thus falling short in ultrafine grinding. Wet grinding, which uses liquid as a grinding background, completely overcomes these shortcomings, making it superior to dry grinding. Sand mills, belonging to wet ultrafine grinding equipment, are characterized by wide material applicability and high efficiency, making them one of the key pieces of equipment for fine material preparation.

[0027] The sand mill industry is relatively mature today, with a wide variety of sand mills available, including vertical enclosed sand mills, horizontal sand mills, and rod mills, which can be used in various industries. As for the production of ultra-clean coal, ultra-clean coal is clean coal with less than 1% ash content obtained after chemical treatment of raw coal. It can be used as an alternative energy source, replacing heavy diesel oil in power generation and on ships.

[0028] Due to the characteristics of ultra-clean coal, it has high requirements for grinding equipment. Horizontal sand mill can continuously grind and disperse solid particles in liquids in a fine manner. It is suitable for various operation modes, has a high output rate, and the grinding media is evenly distributed throughout the grinding cylinder. The flow rate is regulated by the delivery pump, making it very suitable for the grinding requirements of ultra-clean coal. Therefore, it is widely used in the production of ultra-clean coal.

[0029] However, horizontal sand mills are effective at grinding relatively uniform materials that are not prone to sedimentation (such as coatings). Ultra-clean coal slurry, on the other hand, is characterized by its non-uniformity and tendency to settle during transport. Material can easily accumulate in pipelines, causing blockages, overpressure in the feed pump, and even halting the entire ultra-clean coal production unit. Therefore, optimization and improvement are needed in the structure of the sand mill, the selection of the feed pump, and the grinding process.

[0030] Based on this, this application provides an ultra-clean coal production device, such as... Figure 1 As shown, it includes: 1. lifting disperser, 2. feed pump, 3. sand mill, 4. low-speed mixer, 5. pipe, 6. tee, and 7. return pipe;

[0031] The feed pump 2 is connected to the feed inlets of the lifting disperser 1 and the sand mill 3 through a pipe 5, which is used to transport the material initially crushed by the lifting disperser 1 to the sand mill 3 for further grinding.

[0032] The discharge port of the sand mill 3 is connected to the low-speed mixer 4 through a pipe 5, which is used to transport the ground material to the low-speed mixer 4 for mixing to prevent sedimentation.

[0033] The tee 6 is located at the pipe 5 connecting the feed pump 2 and the inlet of the sand mill 3, and is used to connect one end of the return pipe 7. The other end of the return pipe 7 is connected to the lifting disperser 1.

[0034] The lifting disperser 1 is mainly used for crushing, dispersing, emulsifying, and mixing liquid raw materials of different viscosities and slurry forms. It is a new type of high-efficiency stirring equipment that uses the high-speed rotation of the upper and lower serrated teeth of the dispersing disc to subject the materials to high-speed and intense shearing, impact, crushing, and dispersion, achieving rapid mixing, dissolving, dispersing, and refining. In the ultra-clean coal production device of this application, it is also used to provide materials for subsequent grinding.

[0035] The feed pump 2 is used to provide power so that the coal slurry material can circulate in the pipeline 5, realize the transfer of material between the lifting disperser 1, the sand mill 3, and the low-speed mixer 4, and complete the grinding of the material to obtain the final ultra-clean coal product.

[0036] The preferred type of sand mill 3 is the horizontal sand mill described above, which is used to perform ultrafine grinding on the material fed in through the feed inlet and to discharge the ground coal slurry through the discharge outlet and transport it to the low-speed mixer 4 through the pipeline 5.

[0037] The low-speed mixer 4 is used to stir the coal slurry, which on the one hand prevents the coal slurry from settling, and on the other hand makes the coal slurry fully dispersed and uniform.

[0038] It is easy to understand that this application does not impose any restrictions on the model, material and specifications of the above-mentioned lifting disperser 1, feeding pump 2, sand mill 3, low-speed mixer 4 and pipeline 5. Operators can choose the appropriate implementation method to produce ultra-clean coal according to actual needs.

[0039] Additionally, it should be noted that, although Figure 1Although not shown in the diagram, the current lifting disperser 1 is equipped with a material storage tank. The material to be processed is stored in the material storage tank. After undergoing preliminary crushing, dispersion, emulsification, and mixing processes by the lifting disperser 1, it enters the pipeline 5 and is transported to the sand mill 3 for grinding by the power provided by the feed pump 2, and finally goes to the low-speed mixer 4. Similarly, the low-speed mixer 4 is also equipped with a material storage tank for the ground material, which is used to store the material obtained after ultrafine grinding by the sand mill 3.

[0040] The ultra-clean coal production device provided in this application, in addition to existing ultra-clean coal production systems, introduces a return pipe 7 via a three-way valve 6. This allows material to flow back to the material storage tank at the lifting disperser 1 through the return pipe 7 when the feed pump 2 is turned on and its speed is continuously increased, even if the speed of the feed pump 2 is too high. This avoids excessive pulses in the pipeline 5, which could lead to overpressure in the pipeline 5, and also prevents material from accumulating in the grinding chamber of the sand mill 3 due to excessive material being instantaneously delivered. This is beneficial for the stable and safe production of ultra-clean coal. Furthermore, because the return pipe 7 allows material to return to the lifting disperser 1 when overpressure occurs in the pipeline 5, it can be transported back to the sand mill 3 by the power provided by the feed pump 2 in the next cycle, still achieving ultra-fine grinding of ultra-clean coal without wasting material. This helps improve the utilization rate of material in the ultra-clean coal production process and reduce material loss.

[0041] Furthermore, this embodiment provides a preferred implementation scheme for the aforementioned return pipe 7, such as... Figure 1 As shown: The return pipe 7 consists of multiple pipe sections, wherein the pipe connected to the tee 6 in the return pipe 7 is arranged vertically upward.

[0042] Typically, pipes are cylindrical, running straight with a through-hole at both ends. Multiple sections of such pipes are connected by bends at certain angles to form a pipeline. Therefore, using the bends in the return pipeline 7 as dividing points, the return pipeline 7 can be divided into several different sections, among which the section connected to the tee 6 is set vertically upwards.

[0043] Thus, under the influence of gravity, the material usually does not enter the return pipe 7 and will not flow back to the lifting disperser 1. Instead, it flows smoothly into the sand mill 3 for further ultrafine grinding. When overpressure occurs in the pipe, the material overcomes gravity under pressure and enters the return pipe 7, thus returning to the lifting disperser 1. This reduces or even avoids the hazards of material sedimentation caused by overpressure.

[0044] However, it should be noted that the length of the vertically installed loop section is not limited in this embodiment. A longer length better prevents backflow during normal transport of ultra-clean coal, but it also reduces the effectiveness of mitigating pipeline overpressure. Conversely, a shorter length better mitigates overpressure but makes material backflow more likely even when the pipeline pressure is normal. Those skilled in the art can obtain experimental data through multiple trials based on actual conditions to ultimately determine a suitable length for the vertically upward section of the return pipe 7.

[0045] In a preferred embodiment, the end of the return pipe 7 connected to the tee 6 is vertically upward, ensuring that under normal circumstances, material cannot flow into the return pipe 7 due to gravity, thus preventing interference with the normal production process of ultra-clean coal. However, when the feed pump 2 is running at an unstable speed, such as immediately after startup, excessive pulses may occur in the pipe, leading to overpressure. In this case, the pressure in the pipe can overcome gravity, allowing material to flow into the return pipe 7 and then back into the lifting disperser 1. This reduces the overpressure in the pipe, preventing material from accumulating in the pipe and avoiding excessive material flowing into the sand mill 3 in a short period, which could cause material to accumulate in the grinding chamber of the sand mill 3. This further ensures the stable and safe operation of the ultra-clean coal production process.

[0046] To further address the issue of ultra-clean coal easily depositing in pipelines due to its non-uniform and easily deposited characteristics, this embodiment also provides a preferred implementation scheme: the feed pump 2 mentioned above is selected as a flexible hose pump.

[0047] As a type of peristaltic pump, the flexible hose pump works by transporting gaseous, solid, and liquid media in a manner similar to the peristalsis of the digestive tract. The transported medium only comes into contact with the rubber hose, offering good wear resistance and operating at low speeds, making it suitable for transporting slurries. Simultaneously, the impeller, rotor, and cylinder do not contact the liquid, preventing agitation and foaming, allowing direct transport in its original state. Furthermore, since there are no mechanical seals or gland packing, leakage from sealing components is not a concern. Also, due to the lack of sealing parts, the flexible hose pump can be run dry, functioning as a vacuum pump.

[0048] In addition, among all types of pumps, the flexible hose pump has the strongest self-priming capability and can also effectively transport heterogeneous and easily deposited media such as ultra-clean coal, reducing the occurrence of sedimentation.

[0049] Furthermore, since the displacement per revolution is fixed and independent of the outlet pressure, the hose pump is inherently a metering pump. The flow rate of the hose pump is also an important factor affecting the pulse size within the pipeline. While this embodiment does not limit the flow rate of the hose pump, a preferred implementation is provided. Based on actual experimental data, the preferred flow rate of the hose pump is 0.6 cubic meters per hour. This further reduces the possibility of pipeline overpressure and material sedimentation.

[0050] In the preferred embodiments provided above, the preferred solutions for detailed parameters of the commonly used ultra-clean coal production system are provided. For example, the flow rate of the hose pump is preferably 0.6 cubic meters per hour. Similarly, as another important component in the ultra-clean coal production process, the sand mill 3 also has a further preferred solution in this embodiment: for the ultra-clean coal production device provided by the above embodiments, the ring gap between the moving and stationary rings of the sand mill 3 is 1 mm, which is a preferred implementation.

[0051] Existing ultra-clean coal production devices, due to the need to consider the risks of pipeline overpressure and material deposition, have certain requirements on the grinding rate of the sand mill 3. The annular gap between the moving and stationary rings is typically 0.4 mm, which limits the material processing capacity and cannot adequately meet the needs of ultra-clean coal production. The preferred embodiment provided above improves the ultra-clean coal production device from the perspectives of pipeline, structure, and hardware selection. This allows the conveying pipeline to support larger flow rates of material transport and reduces the likelihood of pipeline overpressure and material deposition. Therefore, the annular gap between the moving and stationary rings of the sand mill 3 can be further increased to 1 mm, thereby increasing the material processing efficiency of the sand mill 3 and increasing the amount of ultra-clean coal produced per unit time by the ultra-clean coal production device provided in this application, which better meets actual production needs.

[0052] In summary, this embodiment selects a flexible hose pump as the feed pump 2, leveraging its advantages such as good sealing and strong self-priming capability to achieve the transportation of ultra-clean coal in the pipeline. This reduces the possibility of leakage and sedimentation of the ultra-clean coal, thereby ensuring the safe and stable production of ultra-clean coal in the actual process. Furthermore, in conjunction with the preferred embodiment described above, an optimal form of the flexible hose pump's range parameters is provided. Simultaneously, the annular gap between the moving and stationary rings of the existing sand mill 3 is expanded from the commonly used 0.4mm to 1mm, significantly improving the grinding efficiency of the sand mill 3. This makes it more suitable for the ultra-clean coal production device provided in this application, further improving the production efficiency of ultra-clean coal and better meeting the needs of actual production and daily life.

[0053] Furthermore, in order to reduce the possibility of overpressure in the pipeline, this embodiment also provides a preferred implementation: a pressure buffer tank 8 is provided at the outlet of the feed pump 2.

[0054] As can be seen from the above embodiments, when the feed pump 2 is first started, its speed continuously increases and is not stable. At this time, excessive speed may occur, causing excessive pulse in the pipeline, which in turn leads to overpressure. Although the above embodiments have addressed this problem through various preferred implementation schemes, considering the hazards and losses caused by pipeline overpressure, this embodiment further provides a pressure buffer tank 8 at the outlet of the feed pump 2.

[0055] Thus, when the material flows out of the feed pump 2, it will first pass through the pressure buffer tank 8 before being transported to the subsequent pipeline and the sand mill 3. The material pressure is relieved to a certain extent after passing through the pressure buffer tank 8. Even if the output material pressure of the feed pump 2 is too high due to excessive speed, it can be buffered by the pressure buffer tank 8 to reduce the impact on the subsequent pipeline, thereby further reducing the possibility of pipeline overpressure problems.

[0056] In this embodiment, a pressure buffer tank 8 is installed at the outlet of the feed pump 2, so that the material flowing out of the feed pump 2 first passes through the pressure buffer tank 8 to relieve its pressure. When the feed pump 2 has unstable speed or excessive speed, the pressure in the pipeline can be reduced, reducing or even avoiding the occurrence of pipeline overpressure. This also reduces the phenomenon of material depositing in the pipeline 5 or the grinding chamber of the sand mill 3 due to pipeline overpressure, further ensuring the smooth production of ultra-clean coal.

[0057] As can be seen from the above embodiments, in the process of producing ultra-clean coal, the material should normally flow unidirectionally along the direction of the lifting disperser 1, the feed pump 2, the sand mill 3, and finally to the low-speed mixer 4. If backflow occurs, it will cause serious risks and losses. Therefore, this embodiment provides a preferred solution to solve the material backflow problem that may occur in the pipeline 5: a check valve 9 is installed at the feed inlet of the sand mill 3.

[0058] It is easy to understand that check valves 9 can also be installed at the discharge port of the sand mill 3 and the inlet and outlet ports of other devices. This embodiment is only one possible implementation and is not limited to the ultra-clean coal production device having a check valve 9 only at the inlet port of the sand mill 3.

[0059] Furthermore, based on the above embodiments, this embodiment also provides a possible implementation scheme, wherein the check valve 9 is a swing check valve.

[0060] Swing check valves have a simple and compact structure, which helps control the size of ultra-clean coal production equipment. At the same time, the flow channel of swing check valves is usually open, and the medium encounters less resistance when passing through it, making it less prone to sedimentation and blockage, which is more in line with the requirements for ultra-clean coal production.

[0061] Furthermore, based on the above embodiments, this embodiment provides a preferred implementation where the check valve 9 is a horizontal check valve, meaning the swing check valve is horizontally positioned on the pipe 5 at the feed inlet of the sand mill 3. Compared to a vertically positioned check valve, a horizontal configuration is more conducive to reducing material deposition in the pipe 5. Additionally, adopting this horizontally positioned check valve 9 helps prevent the overflow of zirconium beads used as grinding media and prevents material from depositing at the valve due to gravity, thus preventing valve blockage and providing additional protection for the normal operation of the ultra-clean coal grinding process.

[0062] In addition to the preferred solutions provided in the above embodiments, this embodiment provides another preferred solution to prevent overpressure problems from occurring in the ultra-clean coal production pipeline. Specifically, metal hoses 10 are provided at the inlet and outlet of the sand mill 3.

[0063] It is easy to know that in actual production, in order to ensure reliability and structural stability, pipelines are usually made of rigid materials, and each section of the pipeline is mostly straight. When it is necessary to change the direction of material transmission, they are connected by elbows of various angles, such as 45° elbows and right-angle elbows.

[0064] However, elbows are designed to be as compact as possible to fit the pipe diameter. Consequently, the path that materials take when changing direction in the elbow is also very short. When the angle of the elbow is large, the resistance to the flow of materials in it will be greater, which can easily lead to local overpressure in the pipe and material deposition.

[0065] Therefore, in this embodiment, metal flexible hoses 10 are installed at the inlet and outlet of the sand mill 3, where material deposition is most likely to occur and poses the greatest threat. While ensuring the reliability of the pipeline through metal materials, the hose's ability to bend freely within its limits allows the material to flow more smoothly through the pipeline, thus changing the overall spatial transmission direction. Considering that metal bends do not require the compact design of elbows and have fewer length restrictions, longer metal flexible hoses 10 can be used, allowing the material to travel a longer path for changing direction. Therefore, with a fixed turning angle, the longer the flow path and the gentler the turning angle, the lower the resistance to the material, and the less likely the ultra-clean coal will deposit in the pipeline, or even cause overpressure.

[0066] In a preferred embodiment, metal hoses 10 are installed at both the inlet and outlet of the sand mill 3. This allows the material to obtain a smoother and longer turning path when the transmission direction needs to be changed, thereby reducing the pressure in the turning section of the pipeline. This helps to avoid or mitigate pipeline overpressure and material deposition, further ensuring the smooth production of ultra-clean coal. It also allows the production pipeline to withstand a larger flow rate of material medium, thereby improving the production efficiency of ultra-clean coal and better meeting the needs of actual production and life.

[0067] The above provides a detailed description of an ultra-clean coal production apparatus provided in this application. The various embodiments in the specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

[0068] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A device for producing ultra-clean coal, characterized in that, include: Lifting disperser (1), feed pump (2), sand mill (3), low-speed mixer (4), pipeline (5), tee (6), return pipeline (7) and pressure buffer tank (8); The feed pump (2) is connected to the feed inlets of the lifting disperser (1) and the sand mill (3) through the pipe (5) to transport the material initially crushed by the lifting disperser (1) to the sand mill (3) for further grinding; the pressure buffer tank (8) is located at the outlet of the feed pump (2); The discharge port of the sand mill (3) is connected to the low-speed mixer (4) through the pipe (5) for conveying the ground material to the low-speed mixer (4) for mixing. The tee (6) is located at the pipe (5) connecting the feed pump (2) and the feed inlet of the sand mill (3), and is used to connect one end of the return pipe (7), and the other end of the return pipe (7) is connected to the lifting disperser (1); The return pipeline (7) is composed of multiple sections of the pipeline (5), wherein the pipeline (5) connected to the tee (6) in the return pipeline (7) is arranged vertically upward.

2. The ultra-clean coal production device according to claim 1, characterized in that, The feed pump (2) is a hose pump.

3. The ultra-clean coal production device according to claim 1, characterized in that, A check valve (9) is installed at the feed inlet of the sand mill (3).

4. The ultra-clean coal production device according to claim 3, characterized in that, The check valve (9) is a swing check valve.

5. The ultra-clean coal production device according to claim 4, characterized in that, The check valve (9) is a horizontal check valve.

6. The ultra-clean coal production device according to claim 1, characterized in that, Metal hoses (10) are provided at the inlet and outlet of the sand mill (3).

7. The ultra-clean coal production device according to claim 2, characterized in that, The flow rate of the hose pump is 0.6 cubic meters per hour.

8. The ultra-clean coal production apparatus according to any one of claims 1 to 7, characterized in that, The annular gap between the moving and stationary rings of the sand mill (3) is 1 mm.

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