Nano-scale powder grinding and selection device and powder selection method

Abstract

The present invention discloses a nano-scale powder grinding and selection device and a powder selection method. The nano-scale powder grinding and selection device comprises a grinding mechanism, wherein two or more grading chambers are arranged above the grinding mechanism, and grading wheels are respectively installed in each grading chamber; the powder selection mesh number standard of the grading wheels in the grading chambers of the same layer is the same, and the powder selection mesh number of the grading wheels in the grading chambers of different layers increases layer by layer from bottom to top; except for the grading chamber of the lowest layer, the bottoms of the grading chambers of the other layers are respectively provided with sedimentation powder collectors, and the discharge ports of the sedimentation powder collectors are provided with sedimentation powder output mechanisms; the air outlet of the grading wheel in the uppermost grading chamber is connected to a pulse powder collector. The present invention classifies and takes out the powder by stratification and classification powder selection, thereby ensuring the uniformity of the particle size of the finished powder, and the narrow particle size distribution of the product meets the market's "three degrees" requirements for ultrafine powders, while avoiding the problem of repeated grinding and increasing energy consumption due to the failure to take out some powders that meet the standards in time.

Description

Technical Field

[0001] The invention relates to the technical field of fine powder grinding, and in particular to a nanometer-level powder grinding and selection device and a powder selection method. Background Art

[0002] Nano-powders, also known as nano-powder materials, generally refer to ultrafine particles with a size of about 1-100nm. Nano-powders have large specific surface area, high activity, and improved thermal conductivity, electrical properties, light absorption, and magnetic properties to varying degrees, which makes them increasingly used in electronics, electrical, communications, automobiles, machinery, metallurgy, chemicals, biology, aerospace, national defense and military industries. With the advancement of science and technology and the development of industry, the demand for nano-powders continues to grow.

[0003] The materials processed in the field of nano powders are "three supers", namely: ultrafine particles, physical superhardness, and chemical superpurity. Ultrafine powders must also meet the "three degrees", namely, small particle size (particle size), narrow particle size distribution (width), and small external secondary pollution (purity). The main problem facing industrial production at present is that the width of the powder particle size distribution is too large. The product contains both nano-scale particles and micron-scale particles, and even particles with larger particle sizes, which makes it difficult to meet the market's requirements for nano-scale powders. Manufacturers have tried various methods but have difficulty solving this problem. This is currently a global problem.

[0004] The inventor has more than 20 years of working experience and has been studying the cause of this problem and looking for a solution to the problem. After years of research, he finally figured out the real cause and found a solution to the problem.

[0005] After a long period of research, the inventors found that the current grinding equipment can produce a certain ratio of nano-scale powders during the grinding process of materials. This phenomenon has been confirmed by numerous "laser particle size distribution analyzer" particle size analysis. The problem is that it is difficult for the current powder selection equipment to select this part of nano-scale powders with high purity. The powder selected by the current powder selection equipment contains both nano-scale particles and micron-scale particles, and even particles with larger particle sizes. Although the powder contains some nano-scale particles, because the powder also contains a large number of micron-scale particles, and even particles with larger particle sizes, its particle size distribution is too wide, and the performance of some nano-scale particles is also covered by the particles with larger particle sizes, so it cannot meet the market demand for nano-scale powders with narrow particle size distribution. At present, there is an urgent need to develop a set of equipment that can select ultrafine nano-scale powders, that is, powders with small particle size, narrow particle size distribution, and high purity, to meet the market's "three degrees" requirements for powders.

[0006] At present, the main processing methods for fine powders are: water milling, ball milling, vertical milling, etc.

[0007] Water mills are too inefficient and require drying, which consumes a lot of energy and water resources, causing water pollution and adding additional environmental pressure on sewage treatment.

[0008] The ball milling process is also difficult to produce to meet the market demand for nano-scale powders, and it occupies a large area and has low efficiency, making it difficult to meet market needs.

[0009] The existing vertical mill is also called vertical mill, roller mill, vertical roller mill. The powder it grinds contains a certain proportion of nano-level powder. Its disadvantages are:

[0010] (1) The powder is not graded and the product contains both nano-sized particles and micron-sized particles, which makes it difficult to meet the market demand for nano-sized powders.

[0011] (2) The existing grinding equipment uses multiple classifiers to extract powder according to the same standard at the same time, which results in small-particle and large-particle powders being mixed and taken out at the same time and entering the finished product silo. The product contains both nano-scale particles and micron-scale particles, which makes it difficult to meet the market's demand for high-purity nano-scale powders.

[0012] (3) A set of powder extraction equipment is difficult to extract powder that meets the standards in time, resulting in repeated grinding of some powder that meets the standards, increasing unnecessary energy consumption.

[0013] (4) Although some vertical mills are designed with two sets of powder extraction devices with different standards, which can select powders of different particle sizes from the grinding chamber of the grinding device at the same time, the disadvantage is that powders of various particle sizes are mixed together and are extremely difficult to be classified and selected at the same time. On the one hand, the particle size distribution of the selected powder is too wide and cannot meet the company's "three degrees" requirements for powders. On the other hand, since powders of various particle sizes are mixed together, the efficiency of selecting powders of different particle sizes is extremely low.

[0014] (5) In order to obtain nano-scale powders with a narrow particle size distribution, enterprises use existing grinding equipment, which requires a long period of grinding. As a result, costs have increased dramatically and energy consumption has increased by more than 5 times. Enterprises simply cannot afford it. In addition, long-term high-intensity grinding causes serious damage to the machine, greatly shortening its service life. Summary of the invention

[0015] The technical problem to be solved by the present invention is to provide a nanometer-scale powder grinding and selection device which can gradually narrow the width of powder particle size distribution, reduce the difficulty of powder selection, and maximize the guarantee that powders of different particle sizes are classified and selected, thereby ensuring the "three-degree" requirements of the finished powder.

[0016] In order to solve the above technical problems, the technical solution of the present invention is: a nano-scale powder grinding and selection device, including a grinding mechanism, wherein two or more grading chambers are arranged above the grinding chamber of the grinding mechanism, and at least one grading wheel is installed in each grading chamber; the powder selection mesh number standard of the grading wheels in the grading chambers of the same layer is the same, and the powder selection mesh number of the grading wheels in the grading chambers of different layers increases from the lower layer to the upper layer; the feed inlet of the upper grading chamber is connected to the air outlet of the grading wheel in the adjacent lower grading chamber;

[0017] Except for the lowest grading chamber, the bottoms of the other grading chambers are respectively provided with sedimentation powder collectors for collecting sedimentation powder, the bottoms of the sedimentation powder collectors are respectively provided with discharge ports, and the discharge ports of the sedimentation powder collectors are correspondingly provided with sedimentation powder output mechanisms for outputting the sedimentation powder to the outside of the grading chamber; the grading wheel outlet in the uppermost grading chamber is connected to the pulse powder collector.

[0018] As a preferred technical solution, except for the lowest grading chamber, each of the other grading chambers is provided with a scraping grid mechanism for scraping the settled powder to the discharge port of the settled powder collector.

[0019] As a preferred technical solution, the sedimentation powder collector is an annular concave structure.

[0020] As a preferred technical solution, the grading wheels in each grading chamber are independently controlled.

[0021] As a preferred technical solution, there are two or more grading wheels in the grading chamber on the same floor.

[0022] As a preferred technical solution, the grading wheels in the grading chamber on the same floor are distributed in parallel in a circular shape in the grading chamber or distributed in an interlaced manner in the grading chamber.

[0023] As a preferred technical solution, the sedimentation powder output mechanism is a screw conveyor.

[0024] As a preferred technical solution, the discharge port of the screw conveyor is connected to the sedimentation powder storage silo, and a dust collection device can be set in the sedimentation powder storage silo as needed. In other words, it can be a simple storage silo or a device with both storage and dust collection functions.

[0025] The present invention also provides a powder selection method using the above-mentioned nano-scale powder grinding and selection device, comprising the following steps:

[0026] S1. Finely grind the materials delivered from the raw material bin by grinding rollers and grinding discs, and the ground materials are carried up by high-speed airflow;

[0027] S2. When the material in the airflow passes through the lowest grading chamber, the grading wheel in the lowest grading chamber sorts the powder in the lowest grading chamber according to the set mesh number. The coarse material that does not meet the mesh number requirement is separated and falls into the grinding disc to be re-ground. The powder that meets the mesh number requirement is transported to the second grading chamber for further sorting; the grading wheel in the second grading chamber sorts the powder in the second grading chamber for a second time according to the set mesh number. The powder that is not selected by the grading wheel in the second grading chamber settles in the sedimentation powder collector of the grading chamber of this layer, is scraped to the discharge port by the scraping mechanism, and is transported to the sedimentation powder storage silo for storage by the sedimentation powder output mechanism; and so on, the powder that meets the mesh number standard requirement is finally collected by the pulse powder collector and stored in the finished powder silo.

[0028] Compared with the prior art, the present invention has at least the following beneficial effects:

[0029] (1) The powder selection process is implemented in a layered and classified manner. Starting from the first layer, each layer selects powder in turn. The powder taking operation of each layer of the classification chamber is controlled separately, and each layer is independent and takes what it needs. They are not subordinate to each other and do not interfere with each other. Starting from the first layer, different mesh selection standards are set for each layer. The mesh increases layer by layer, and the specific mesh value is set according to needs. After the powder selected by the first layer classification chamber (first-level classification wheel) enters the second layer classification chamber, when the second layer classification chamber (second-level classification wheel) performs powder selection, the powder between the mesh set for the first and second-level powder selection cannot be selected by the second-level powder selection. This part of the powder is collected and discharged by the powder sedimentation collection method; through layered and classified powder selection, the width of the powder particle size distribution can be gradually narrowed, the difficulty of powder selection in each classification chamber can be reduced, the powder selection efficiency can be improved, and the powder of different particle sizes can be classified and selected to the greatest extent.

[0030] (2) After stratified and classified powder selection, the powders are graded and taken out and put into different silos respectively, meeting the needs of different enterprises for powders of different particle sizes and ensuring the uniformity of the particle size of the finished powders, especially the narrow particle size distribution (width) of the product. Nano- and micron-sized powders are truly selected, meeting the market's "three-degree" requirements for ultrafine powders, avoiding the problem of powders of various particle sizes being mixed together and taken out, resulting in a too wide (width) powder size distribution, and solving the global problem of products containing both nano-sized particles and micron-sized particles or even larger particles.

[0031] (3) Based on the original vertical mill, only the grading chamber and grading wheel are added in the powder taking process, which does not change the normal grinding working process of the original mill, does not affect the grinding efficiency, and does not increase the energy consumption of any grinding process.

[0032] (4) Powders of various particle sizes ground out during the grinding process can be classified and taken out in a timely manner, avoiding the problem of some powders that meet the standards not being taken out in time and repeated grinding to increase energy consumption, avoiding serious damage to the machine due to long-term high-intensity grinding, and greatly extending the service life of the machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The following drawings are intended only to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0034] Figure 1 is a schematic structural diagram of Embodiment 1 of the present invention;

[0035] Figure 2 It is a reference diagram of the state of powder in each layer of the grading chamber in the first embodiment of the present invention;

[0036] Figure 3 It is a schematic structural diagram of a sedimentation powder collector and a scraper mechanism in the first embodiment of the present invention;

[0037] Figure 4 It is a schematic diagram of the modified structure of the sedimentation powder collector and the scraper mechanism;

[0038] Figure 5 is a schematic structural diagram of a pulse powder collector in Embodiment 1 of the present invention;

[0039] Figure 6 is a structural diagram of Embodiment 2 of the present invention;

[0040] Figure 7 It is a reference diagram of the state of powder in each layer of the grading chamber in the second embodiment of the present invention.

[0041] In the figure: 10-grinding mechanism; 11-grinding disc; 12-grinding roller; 13-driving motor; 21-first layer classification chamber; 211-first level classification wheel; 22-second layer classification chamber; 221-second level classification wheel; 30-sedimentation powder collector; 31-discharge port; 32-inner wall; 33-inner ring; 34-outer ring; 40-sedimentation powder output mechanism; 50-sedimentation powder storage silo; 60-pulse powder collector; 61-powder collection chamber; 62-clean air chamber; 63-filter bag; 64-collection silo; 70-scraping grid mechanism; 71-scraper; 72-scraper shaft; 73-scraper motor; 81-ground material; 82-powder after the first sorting; 83-powder after the second sorting; 84-powder not selected by the second level classification wheel; 85-powder after the third sorting; 90-raw material silo. DETAILED DESCRIPTION

[0042] The present invention is further described below in conjunction with the accompanying drawings and examples. In the following detailed description, certain exemplary embodiments of the present invention are described only by way of illustration. Needless to say, those of ordinary skill in the art will recognize that the described embodiments may be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the drawings and description are illustrative in nature and are not intended to limit the scope of protection of the claims.

[0043] In the description of the present invention, it should be noted that the terms "top", "bottom", "horizontal", "interlaced", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", "primary", "secondary", "tertiary" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0044] Embodiment 1

[0045] like Figure 1 As shown, the nano-scale powder grinding and selection device proposed by the present invention is representatively illustrated. In this exemplary embodiment, the application to calcium carbonate is used as an example for explanation. It is easy for those skilled in the art to understand that in order to apply the relevant design of the present disclosure to other types of materials or other processes, various modifications, additions, substitutions, deletions or other changes are made to the following specific embodiments, and these changes are still within the scope of protection of the present invention.

[0046] refer to Figures 1 to 5 In this embodiment, the nano-powder grinding and selection device includes a grinding mechanism 10, a first-layer classification chamber 21, a second-layer classification chamber 22, a sedimentation powder collector 30, a sedimentation powder output mechanism 40, a sedimentation powder storage silo 50 and a pulse powder collector 60.

[0047] The grinding mechanism 10 includes a grinding disc 11, a grinding roller 12, and a driving motor 13. The material in the raw material bin 90 is fed into the grinding disc 11 through a feeder. The grinding disc 11 is driven by the driving motor 13, and the material enters between the grinding roller 12 and the grinding disc 11 to be ground into powder. The ground material 81 is carried upward by the high-speed airflow and passes through the classification chamber. The above structure is a well-known and commonly used structure of a vertical mill, and will not be described in detail here.

[0048] One or more first-level classifying wheels 211 are installed in the first-level classifying chamber 21. Each first-level classifying wheel 211 is independently driven by a motor, and the powder selection mesh number standard is the same. The specific powder selection mesh number standard can be achieved by adjusting the blade gap and the speed, so as to select all powders with a particle size of a certain size or above. For example, the powder selection particle size can be set to 1000 mesh and above 1000 mesh until nano-scale powder. After setting the mesh number, the first-level classifying wheel 211 will select the powder that meets the conditions (i.e., the powder 82 after the first sorting) and transport it to the second-level classifying chamber 22 for further sorting; the coarse material that does not meet the mesh number requirements will be separated and fall into the grinding disc for re-grinding. In this embodiment, the first-level classifying wheel 211 is shown as two, which are distributed in parallel in a ring shape in the first-level classifying chamber 21. Of course, the first-level classifying wheel 211 can also be other numbers or other installation methods, and can be appropriately installed in a variety of ways such as horizontal, longitudinal, annular parallel distribution, and staggered up and down according to actual needs, which should all belong to the protection scope of the present invention.

[0049] The inlet of the second-layer classification chamber 22 is connected to the outlet of the first-layer classification wheel 211; one or more second-layer classification wheels 221 are installed in the second-layer classification chamber 22. Similarly, the powder selection mesh number standard of each second-layer classification wheel 221 is the same, and further sorting is performed on the basis of the first-layer sorting. For example, the powder selection particle size can be set to 5000 mesh and above 5000 mesh until nano-scale powder. After setting the mesh number, the second-layer classification wheel 221 will select the powder that meets the conditions (i.e., the powder 83 after the second sorting) and output it to the pulse powder collector 60 for collection.

[0050] refer to Figure 5 The structure principle of the pulse powder collector 60 is the same as that of the pulse dust collector, including a powder collecting chamber 61 and a clean air chamber 62. The side wall of the powder collecting chamber 61 is provided with a powder inlet 65, which is connected to the air outlet of the upper-level classification wheel (the secondary classification wheel in this embodiment) through a pipeline. A plurality of filter bags 63 are installed in the powder collecting chamber 61, and a collection bin 64 is provided at the bottom of the powder collecting chamber 61. During operation, the powder selected by the secondary classification wheel 221 enters the powder collecting chamber 61 with the air flow, and the powder directly settles in the collection bin 64 or accumulates on the surface of the filter bag 63. The filtered gas enters the clean air chamber 62 and is discharged to the atmosphere through the exhaust fan.

[0051] refer to Figure 2A sedimentation powder collector 30 is arranged at the top of the first-layer classification chamber 21 and at the bottom of the second-layer classification chamber 22. A discharge port is arranged at the bottom of the sedimentation powder collector 30. A sedimentation powder output mechanism 40 is arranged at the discharge port of the sedimentation powder collector 30. The sedimentation powder output mechanism 40 can be a screw conveyor or the like. A scraper mechanism 70 is also arranged in the second-layer classification chamber 22. The powder 84 (i.e., powder outside the set mesh number) that enters the second-layer classification chamber 22 but is not selected by the secondary classification wheel is settled on the collector by natural sedimentation. The settled powder is scraped and sent to the discharge port 31 of the sedimentation powder collector 30 by the scraper mechanism 70, and then transported to the sedimentation powder storage silo 50 by the sedimentation powder output mechanism 40 for storage.

[0052] refer to Figure 3 In this embodiment, the sedimentation powder collector 30 preferably adopts a conical ring-shaped concave structure with a large diameter at the upper end and a small diameter at the lower end. This design will form an air vortex, which is more conducive to the sedimentation and collection of powder. Correspondingly, the scraper mechanism 70 includes a scraper 71 extending along the inner wall 32 of the sedimentation powder collector 30, a scraper shaft 72, and a scraper motor 73 driving the scraper shaft 72 to rotate. The scraper 71 is fixedly mounted on the scraper shaft 72. When the scraper 71 rotates, the sedimentation powder is scraped and sent to the discharge port 31 of the sedimentation powder collector 30.

[0053] Of course, there are other modifications to the sedimentation powder collector 30 and the scraper mechanism 70. For example Figure 4 As shown, the sedimentation powder collector 30 can be modified into a concentric ring structure, the inner ring 33 is a conical ring-shaped concave structure with a large diameter at the upper end and a small diameter at the lower end, a powder rising channel is formed between the inner ring 33 and the outer ring 34, and the outer wall of the outer ring 34 is inclined downward and abuts against the inner wall of the grading chamber to form a larger sedimentation surface. The above modified structures should all fall within the protection scope of the present invention.

[0054] Embodiment 2

[0055] The structural principles of this embodiment are basically the same as those of the first embodiment, and the similarities will not be repeated here. The only difference is that this embodiment takes a three-layer classification chamber as an example.

[0056] refer to Figure 6 and Figure 7, the inlet of the third-layer classification chamber 23 is connected to the outlet of the secondary classification wheel 221; one or more three-level classification wheels 231 are installed in the third-layer classification chamber 23, and the powder selection mesh number standard of each three-level classification wheel 231 is the same. After the secondary classification wheel 221 selects and transports the qualified powder to the third-layer classification chamber 23 (i.e., the powder 83 after the second sorting), it can be further sorted on the basis of the secondary sorting through the three-level classification wheel 231. The three-level classification wheel 231 will select the qualified powder (i.e., the powder 85 after the third sorting) and output it to the pulse powder collector 60 for collection. For example, the powder selection particle size of the three-level classification wheel can be set to 8000 mesh and above 8000 mesh until nano-level powder. Of course, when more layers are set, the powder selection principle is similar, and nano-level and micron-level powders can be truly selected in the end.

[0057] As mentioned above, powders of various particle sizes are layered and classified and selected in turn in the powder selection process. The powder collection operations of each layer of the classification chamber are controlled separately, and each is independent and takes what it needs. They are not subordinate to each other and do not interfere with each other. Starting from the first layer, each layer sets a powder selection standard with different mesh numbers, and the mesh numbers increase layer by layer. The specific mesh number values ​​are set according to needs. After the powder selected by the first layer classification chamber (first-level classification wheel) enters the second layer classification chamber, when the second layer classification chamber (second-level classification wheel) performs powder selection, the powder between the mesh numbers set for the first and second-level powder selection cannot be selected by the second-level powder selection. This part of the powder is collected and discharged by the powder sedimentation collection method; through layered powder selection and classified powder selection, the width of the powder particle size distribution can be gradually narrowed, the difficulty of secondary and tertiary powder selection can be reduced, and the powder selection efficiency can be greatly improved, which can maximize the guarantee that powders of different particle sizes are classified and selected efficiently.

[0058] After stratified powder selection and classified powder selection, the powders are graded and taken out and enter different silos respectively, meeting the needs of different companies for powders of different particle sizes and ensuring the uniformity of the particle size of the finished powders, especially the narrow particle size distribution of the product. In the end, nano- and micron-sized powders can be truly selected, meeting the market's "three degrees" requirements for ultrafine powders, avoiding the problem of powders of various particle sizes being mixed together and taken out, resulting in a too wide (width) powder size distribution, and solving the global problem of products containing both nano- and micron-sized particles or even larger particles.

[0059] The present invention is based on the original vertical mill, and only adds a grading device in the powder taking link, which does not change the normal grinding working link of the original mill, does not affect the grinding efficiency, and does not increase the energy consumption of any grinding link. Since the powders of various particle sizes ground out in the grinding link can be timely classified and taken out, the problem of some powders that meet the standards not being taken out in time and repeatedly grinding to increase energy consumption is avoided, and the serious loss of the machine due to long-term high-intensity grinding is avoided, and the service life of the machine is greatly extended.

[0060] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. For example, the classification chamber may be four, five or more layers, and the number of classification wheels in each classification chamber may be three, four or more, and any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A nano-scale powder grinding and selection device, comprising a grinding mechanism, wherein the grinding mechanism comprises a grinding roller and a grinding disc; characterized in that: Two or more grading chambers are arranged above the grinding chamber of the grinding mechanism, at least one grading wheel is installed in each grading chamber, and the grading wheels in each grading chamber are independently controlled; the powder selection mesh number standard of the grading wheels in the grading chambers on the same layer is the same, and the powder selection mesh numbers of the grading wheels in the grading chambers on different layers increase from the lower layer to the upper layer; the feed inlet of the grading chamber on the upper layer is connected to the air outlet of the grading wheel in the grading chamber on the adjacent lower layer; Except for the lowest grading chamber, the bottoms of the other grading chambers are respectively provided with sedimentation powder collectors for collecting sedimentation powders. The sedimentation powder collectors are concentric ring structures, and the inner ring is a conical ring-shaped inner concave structure with a large diameter at the upper end and a small diameter at the lower end. A powder ascending channel is formed between the inner ring and the outer ring, and the outer wall of the outer ring is inclined downward and abuts against the inner wall of the grading chamber; the bottoms of the sedimentation powder collectors are respectively provided with discharge ports, and the discharge ports of the sedimentation powder collectors are correspondingly provided with sedimentation powder output mechanisms for outputting the sedimentation powders to the outside of the grading chamber; Except for the lowest grading room, each of the other grading rooms is provided with a scraper mechanism for scraping the settled powder to the discharge port of the settled powder collector; the scraper mechanism includes a scraper, a scraper shaft and a scraper motor for driving the scraper shaft to rotate, the scraper is fixedly mounted on the scraper shaft, and the scraper scrapes the settled powder to the discharge port of the settled powder collector when rotating; The air outlet of the classifying wheel in the uppermost classifying chamber is connected to the pulse powder collector.

2. The nano-scale powder grinding and selection device according to claim 1, characterized in that: There are two or more grading wheels in the grading room on the same floor.

3. The nano-scale powder grinding and selection device according to claim 2, characterized in that: The grading wheels in the grading room on the same floor are distributed in parallel in a circular shape in the grading room.

4. The nano-powder grinding and selection device according to claim 2, characterized in that: The grading wheels in the grading room on the same floor are distributed in the grading room in an annular and staggered manner.

5. The nano-scale powder grinding and selection device according to claim 1, characterized in that: The sedimentation powder output mechanism is a screw conveyor.

6. The nano-powder grinding and selection device according to claim 5, characterized in that: The discharge port of the screw conveyor is connected to the sedimentation powder storage silo.

7. A powder selection method using the nano-scale powder grinding and selection device according to any one of claims 1 to 6, characterized in that: The steps include: S1. Finely grind the materials delivered from the raw material bin by grinding rollers and grinding discs, and the ground materials are carried up by high-speed airflow; S2. When the material in the airflow passes through the lowest grading chamber, the grading wheel in the lowest grading chamber sorts the powder in the lowest grading chamber according to the set mesh number. The coarse material that does not meet the mesh number requirement is separated and falls into the grinding disc to be re-ground. The powder that meets the mesh number requirement is transported to the second grading chamber for further sorting; the grading wheel in the second grading chamber sorts the powder in the second grading chamber for a second time according to the set mesh number. The powder that is not selected by the grading wheel in the second grading chamber settles in the sedimentation powder collector of the grading chamber of this layer, is scraped to the discharge port by the scraping mechanism, and is transported to the sedimentation powder storage silo for storage by the sedimentation powder output mechanism; and so on, the powder that meets the mesh number standard requirement is finally collected by the pulse powder collector and stored in the finished powder silo.

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