A zinc powder pneumatic conveying system

Abstract

This invention discloses a zinc powder pneumatic conveying system, comprising: an air supply unit providing a stable constant-pressure carrier air source for the pneumatic conveying system; a mixing and conveying unit for mixing zinc powder with solid lubricating powder and conveying the material; and a graded storage and recovery unit for graded storage of zinc powder of different particle sizes and recovery of solid lubricating powder mixed in with the zinc powder, as well as the conveying carrier air. By introducing solid lubricating powder, which is uniformly mixed with and coats the zinc powder surface, the original collision and friction between zinc powder particles and between zinc powder and the pipe wall is transformed into collision and friction between lubricating powder particles and between zinc powder and the pipe wall. This significantly reduces the wear of the conveying pipeline by zinc powder, effectively extends the service life of the conveying pipeline, and thus avoids safety accidents caused by pipeline wear-through, ensuring the safe operation of the conveying system.

Description

Technical Field

[0001] This invention relates to the field of powder material conveying technology, and in particular to a zinc powder pneumatic conveying system. Background Technology

[0002] Ultrafine zinc powder, due to its low surface oxidation, high activity, and low bulk density, is widely used in the coatings industry and is also an important raw material in metallurgy, chemical industry, battery industry, pharmaceutical industry, automotive industry, and shipbuilding industry. The actual industrial manufacturing process of ultrafine zinc powder can be divided into two main steps: powder preparation and classification. In between, there is also a zinc powder transfer process (i.e., zinc powder transportation process). The stable, consistent, and efficient operation of this process plays a crucial role in the production of ultrafine zinc powder.

[0003] Currently, the transfer process of ultrafine zinc powder is carried out manually, using unloading vehicles or trolleys. Although this method has low design costs, it suffers from many drawbacks, including low productivity, high labor intensity, low automation, severe dust pollution, and a high risk of occupational diseases. Therefore, Wang Yanjun, in his article "Application of Gas Conveying Technology in Zinc Powder Transfer Process," proposed using pneumatic conveying technology to complete the zinc powder transfer process, arguing that this method can avoid the main defects of traditional methods. However, he did not design a reasonable pneumatic conveying device. Meanwhile, Chinese invention patent CN115215101A, considering the large specific surface area and extremely high activity of ultrafine zinc powder, its correspondingly low ignition point and explosion limits, and its tendency to react with moisture and oxygen in the air to release a large amount of heat, potentially causing fires or explosions, discloses "a long-distance pneumatic conveying system for zinc powder using nitrogen protection." This invention patent introduces nitrogen as the carrier gas and forms a closed-loop circulation. On the one hand, it can prevent the contact reaction between moisture and oxygen and zinc powder, thus preventing zinc powder combustion and explosion; on the other hand, it can save gas consumption and reduce operating costs. However, this method does not take into account the problems of pipe blockage and wear during zinc powder transportation. Due to the high viscosity of ultrafine zinc powder, it is prone to agglomeration; thus, a large amount of ultrafine zinc powder will accumulate in the horizontal pipes and bends of the transportation system, causing transportation instability; it may even further lead to pipe blockage, thereby interrupting the pneumatic transportation process and paralyzing the ultrafine zinc powder preparation system. In addition, ultrafine zinc powder has high hardness, which causes severe wear on related transportation equipment, especially transportation pipes, during transportation, directly affecting the life of transportation pipes and increasing operating costs; it may even lead to pipe wear-through accidents, causing safety hazards. Therefore, whether these two problems (blockage and wear), especially wear, can be successfully solved is the key to determining whether the zinc powder pneumatic transportation device can operate "stable, full, and efficient". Summary of the Invention

[0004] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0005] The technical problem this invention aims to solve is that ultrafine zinc powder has a high hardness, which causes severe wear on related conveying equipment, especially conveying pipelines, during the conveying process. This directly affects the lifespan of the conveying pipelines and may even lead to pipeline wear-through accidents, thereby causing safety incidents.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a zinc powder pneumatic conveying system, comprising: an air supply unit for providing a stable constant pressure carrier air source for the pneumatic conveying system; a mixing and conveying unit for mixing zinc powder with solid lubricating powder and conveying the material; and a graded storage and recovery unit for graded storage of zinc powder of different particle sizes and recovery of solid lubricating powder mixed in zinc powder, as well as conveying carrier air.

[0007] In a preferred embodiment of the zinc powder pneumatic conveying system of the present invention, the air supply unit includes an air compressor, a nitrogen storage tank, and a high-pressure nitrogen transmission pipe. The air inlet of the air compressor is connected to a graded storage and recovery unit to facilitate the recycling of the filtered conveying carrier air. The air outlet of the air compressor is connected to the air inlet of the nitrogen storage tank through a transmission pipe. The air outlet of the nitrogen storage tank is connected to a mixing and conveying unit through a high-pressure nitrogen transmission pipe to facilitate the conveying of materials.

[0008] In a preferred embodiment of the zinc powder pneumatic conveying system of the present invention, the mixing and conveying unit includes a hopper, a mixing agitator, a first rotary feeder, a lubricating powder injector, a second rotary feeder, a material guide pipe, and a conveying pipeline. The upper part of the hopper is connected to the condenser in the zinc powder preparation process, and the lower part of the hopper is connected to the mixing agitator through the first rotary feeder to feed zinc powder into the mixing agitator. The lubricating powder injector is symmetrically arranged around the mixing agitator to ensure that the lubricating powder is sprayed into the mixing agitator more evenly. The second rotary feeder is located below the mixing agitator, and the material guide pipe is located on the second rotary feeder. The high-pressure nitrogen gas supply pipe, the conveying pipeline, and the material guide pipe are connected by a tee. The material guide pipe is used to change the flow direction of the material to prevent zinc powder from directly impacting the pipe wall, reducing impact wear, reducing material kinetic energy loss, and reducing conveying energy consumption.

[0009] In a preferred embodiment of the zinc powder pneumatic conveying system of the present invention, the graded storage and recovery unit includes a first main classifier, a second main classifier, a cyclone dust collector, a bag filter, and a nitrogen outlet pipe. The inlet end of the first main classifier is connected to the conveying pipeline, the inlet end of the second main classifier is connected to the outlet end of the first main classifier, the inlet end of the cyclone dust collector is connected to the outlet end of the second main classifier, and is used to separate zinc powder of different particle sizes for separate storage. The inlet end of the bag filter is connected to the outlet end of the cyclone dust collector, and is used to collect fine solid lubricating powder in the carrier gas, thereby filtering the carrier gas. The outlet end of the bag filter is connected to the inlet end of the air compressor through a nitrogen outlet pipe.

[0010] In a preferred embodiment of the zinc powder pneumatic conveying system of the present invention, the conveying pipeline includes a horizontal conveying pipe, a first bend, a vertical pipe, and a connecting bend. The inlet end of the horizontal conveying pipe, the outlet end of the material guide pipe, and the outlet end of the high-pressure nitrogen conveying pipe are connected in the form of a tee. The inlet end of the first bend is connected to the outlet end of the horizontal conveying pipe, and the outlet end of the first bend is connected to the inlet end of the vertical pipe. The outlet end of the vertical pipe is connected to the inlet end of the connecting bend. The outlet end of the connecting bend is connected to the graded storage and recycling unit. A spherical chamber is provided inside the first bend, and a guide plate is provided inside the connecting bend to achieve the effects of anti-wear and anti-blocking during the conveying process.

[0011] As a preferred embodiment of the zinc powder pneumatic conveying system of the present invention, the mixing and conveying unit further includes an electronic scale, which is located below the mixing agitator and is used to monitor the mass flow rate of the material to ensure that the pneumatic conveying system is always in dense phase pneumatic conveying mode to achieve the best anti-wear effect.

[0012] As a preferred embodiment of the zinc powder pneumatic conveying system of the present invention, both the first rotary feeder and the second rotary feeder are equipped with anti-jamming baffles to prevent the rotary feeders from jamming when a large amount of material is conveyed.

[0013] As a preferred embodiment of the zinc powder pneumatic conveying system of the present invention, the first main classifier is equipped with a first pressure sensor and an electric pressure relief valve to regulate the pressure and ensure the stable operation of the dense phase pneumatic conveying process.

[0014] The beneficial effects of this invention are:

[0015] 1. By introducing solid lubricating powder, it is uniformly mixed with zinc powder and coated on the surface of zinc powder. The original collision and friction between zinc powder and between zinc powder and pipe wall is transformed into collision and friction between lubricating powder and zinc powder and between lubricating powder and pipe wall. This greatly reduces the wear of zinc powder on the conveying pipeline, effectively extends the service life of the conveying pipeline, and avoids safety accidents caused by pipeline wear-through, thus ensuring the safe operation of the conveying system.

[0016] 2. By adopting a dense-phase pneumatic conveying method, and supplementing it with a reasonable arrangement of conveying pipelines, the effects of wear prevention and blockage prevention in the conveying process can be achieved;

[0017] 3. Solid lubricating powder is recovered by bag filter and the conveying air is filtered, realizing the recycling of solid lubricating powder and conveying air, thus reducing operating costs. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0019] Figure 1 This is a schematic diagram of the overall structure of a zinc powder pneumatic conveying system.

[0020] Figure 2 This is a schematic diagram showing the position and structure of the second rotary feeder and the material guide pipe in a zinc powder pneumatic conveying system.

[0021] Figure 3 This is a schematic diagram of the horizontal conveying pipe of a zinc powder pneumatic conveying system.

[0022] Figure 4 This is a schematic diagram of the first bend in the pneumatic conveying system for zinc powder.

[0023] Figure 5 This is a schematic diagram of the connecting bend in a zinc powder pneumatic conveying system.

[0024] In the diagram: 1. Air supply unit; 11. Air compressor; 12. Nitrogen storage tank; 13. High-pressure nitrogen transmission pipe; 2. Mixing and conveying unit; 21. Hopper; 22. First rotary feeder; 23. Lubricating powder injector; 24. Mixing agitator; 25. Electronic scale; 26. Second rotary feeder; 261. Anti-jamming baffle; 27. Material guide pipe; 28. Horizontal conveying pipe; 281. Horizontal main conveying pipe; 2811. Second pressure sensor; 2812. Flow meter; 2 82. Horizontal internal bypass pipe; 2821. Fixed groove; 28211. Circular hole groove; 28212. Air inlet groove; 29. ​​First bend pipe; 291. Spherical chamber; 210. Vertical pipe; 211. Connecting bend pipe; 2111. Guide plate; 3. Graded storage and recycling unit; 31. First main classifier; 311. First pressure sensor; 312. Electric pressure relief valve; 32. Second main classifier; 33. Cyclone dust collector; 34. Bag dust collector; 35. Nitrogen outlet pipe. Detailed Implementation

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0026] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments. Example

[0028] Reference Figures 1-5This embodiment provides a zinc powder pneumatic conveying system, comprising: an air supply unit 1, which provides a stable constant pressure carrier air source for the pneumatic conveying system, enabling the material to be safely and stably conveyed in a dense phase pneumatic conveying mode; a mixing and conveying unit 2, which uniformly mixes zinc powder and solid lubricating powder and conveys the material, significantly improving the material flowability and reducing energy and air consumption during the conveying process; at the same time, the pipe wear problem is also effectively controlled; and a graded storage and recovery unit 3, which is used for graded storage of zinc powder of different particle sizes and recovery of solid lubricating powder mixed in zinc powder and conveying carrier air. By introducing solid lubricating powder, it is uniformly mixed with zinc powder and coated on the surface of zinc powder, changing the original collision and friction between zinc powder and zinc powder and between zinc powder and pipe wall to the collision and friction between lubricating powder and zinc powder and between lubricating powder and pipe wall, greatly reducing the wear of zinc powder on the conveying pipe, effectively extending the service life of the conveying pipe, thereby avoiding safety accidents caused by pipe wear-through, ensuring the safe operation of the conveying system, and also achieving the effect of significantly saving conveying energy consumption and operating costs.

[0029] Specifically, the gas supply unit 1 includes an air compressor 11, a nitrogen storage tank 12, and a high-pressure nitrogen transmission pipe 13. The air compressor 11's inlet is connected to the staged storage and recovery unit 3, and its outlet is connected to the nitrogen storage tank 12's inlet via a transmission pipe, allowing filtered nitrogen to be transported into the nitrogen storage tank 12 for recycling and reducing system operating costs. The nitrogen storage tank 12's outlet is connected to the mixing and conveying unit 2 via the high-pressure nitrogen transmission pipe 13, transporting nitrogen to the mixing and conveying unit 2 for material transport. The high-pressure nitrogen transmission pipe 13 is equipped with a shut-off valve and a rotor flow meter 2812 for detecting and regulating nitrogen flow. The nitrogen storage tank 12 has a pressure regulating valve to control nitrogen pressure, providing a stable pressure source for the entire pneumatic conveying system.

[0030] The mixing and conveying unit 2 includes a hopper 21, a mixing agitator 24, a first rotary feeder 22, a lubricating powder injector 23, a second rotary feeder 26, a material guide pipe 27, and a conveying pipeline. The upper part of the hopper 21 is connected to the condenser in the zinc powder preparation process, and the lower part of the hopper 21 is connected to the mixing agitator 24 through the first rotary feeder 22. The zinc powder in the hopper 21 is fed into the mixing agitator 24 through the first rotary feeder 22. The lubricating powder injector 23 is symmetrically arranged around the mixing agitator 24, and the lubricating powder is evenly sprayed into the mixing agitator 24. The mixing agitator 24 thoroughly mixes the lubricating powder and zinc powder, so that the lubricating powder and zinc powder are evenly mixed and coated on the surface of the zinc powder, thus transforming the original collision and friction between zinc powder particles and between zinc powder and pipe wall. The collision and friction between the lubricating powder and zinc powder, and between the lubricating powder and the pipe wall, greatly reduces the wear of the conveying pipe by the zinc powder, effectively extending the service life of the conveying pipe and thus avoiding safety accidents caused by pipe wear-through. The second rotary feeder 26 is installed below the mixing agitator 24, and the material guide pipe 27 is installed on the second rotary feeder 26. The high-pressure nitrogen gas transmission pipe 13, the conveying pipeline, and the material guide pipe 27 are connected by a tee. The lubricating powder and zinc powder mixed in the mixing agitator 24 are conveyed into the conveying pipeline through the material guide pipe 27 via the second rotary feeder 26. The material guide pipe 27 is used to change the flow direction of the material so that it is the same as the flow direction of the high-pressure nitrogen. This not only prevents the material from directly impacting the pipe wall and causing wear, but also reduces the kinetic energy loss of the material and reduces the energy consumption of the conveying.

[0031] It should be noted that the solid lubricating powder in the lubricating powder injector 23 is made of graphite powder. This is because it does not react with zinc powder; and because graphite powder has a small particle size and light weight, it can be adsorbed onto the surface of zinc powder and form a coating effect by interparticle forces (van der Waals forces, electric field forces, etc.). At the same time, it is also easy to separate and recycle the lubricating powder in the graded storage and recycling unit.

[0032] The graded storage and recycling unit 3 includes a first main classifier 31, a second main classifier 32, a cyclone dust collector 33, a bag filter dust collector 34, and a nitrogen outlet pipe 35. The inlet end of the first main classifier 31 is connected to the conveying pipeline, the inlet end of the second main classifier 32 is connected to the outlet end of the first main classifier 31, the inlet end of the cyclone dust collector 33 is connected to the outlet end of the second main classifier 32, and the inlet end of the bag filter dust collector 34 is connected to the outlet end of the cyclone dust collector 33. The material enters the first main classifier 31 through the conveying pipeline, then enters the second main classifier 32, and then passes through the second main classifier... 32 enters the cyclone dust collector 33, and finally enters the bag dust collector 34. The first main classifier 31, the second main classifier 32 and the cyclone dust collector 33 separate zinc powder of different particle sizes and store them separately. The bag dust collector 34 is used to collect fine solid lubricating powder in the carrier gas and plays the role of filtering the carrier gas. The collected lubricating powder can also be added back into the lubricating powder injector 23 for recycling, reducing the loss of solid lubricating powder. The outlet end of the bag dust collector 34 is connected to the air inlet end of the air compressor 11 through the nitrogen outlet pipe 35, so that the filtered nitrogen can be recycled and reduced gas consumption.

[0033] The conveying pipeline includes a horizontal conveying pipe 28, a first bend 29, a vertical pipe 210, and a connecting bend 211. The inlet end of the horizontal conveying pipe 28 is connected to the outlet end of the material guide pipe 27. The inlet end of the first bend 29 is connected to the outlet end of the horizontal conveying pipe 28. The outlet end of the first bend 29 is connected to the inlet end of the vertical pipe 210. The outlet end of the vertical pipe 210 is connected to the inlet end of the connecting bend 211. The outlet end of the connecting bend 211 is connected to the graded storage and recycling unit 3.

[0034] The horizontal conveying pipe 28 mainly consists of a horizontal main conveying pipe 281 and a horizontal inner bypass pipe 282. A fixed groove 2821 is provided on the horizontal inner bypass pipe 282, which mainly consists of a circular hole groove 28211 and an air inlet groove 28212. Because the flow resistance of the horizontal inner bypass pipe 282 is greater than that of the horizontal main conveying pipe 281, during normal conveying, the horizontal inner bypass pipe 282 has little impact on the horizontal main conveying pipe 281, and the carrier gas and material mainly flow within the horizontal main conveying pipe 281. When a large amount of material accumulates in the horizontal main conveying pipe 281 and may cause… When a blockage occurs, the airflow resistance increases, and a large amount of carrier gas enters the horizontal inner bypass pipe 282 from the inlet slot 28212. This generates a jet of airflow at the circular slot 28211, creating a strong turbulent effect. This results in a pressure difference between the two inlet slots 28212 exceeding the pressure of the material section between the two conveying points. The airflow is then ejected at high speed from the other inlet slot 28212 and flows back into the horizontal main conveying pipe 281, creating turbulence in this area. This turbulence continuously disturbs and disperses a large amount of deposited material, causing it to continue moving forward in a wave-like form, thus preventing pipe blockage and ensuring trouble-free material conveying. Furthermore, when the airflow is ejected at high speed from the other inlet slot 28212, it creates a strong flow around the fixed slot 2821, causing severe wear on the pipe wall. The lubricating powder in the material can greatly mitigate the severe wear below the fixed slot 2821 caused by the flow around the fixed slot. Additionally, a second pressure sensor 2811 and a flow meter 2812 are installed on the horizontal main conveying pipe 281 to monitor the pressure and flow rate within the horizontal main conveying pipe 281.

[0035] The first bend 29 adopts a pipe structure with an internal spherical chamber 291. On the one hand, it can increase the flow space of materials, which is conducive to pipe dredging and thus prevents blockage. On the other hand, the first bend can also play a certain guiding role, reduce the collision and friction of materials on the pipe wall, and reduce pipe wear. The connecting bend 211 adopts a pipe structure with a large radius of curvature, and a guide plate 2111 is set inside the connecting bend 211 to guide the flow of materials, reduce the kinetic energy loss of materials, and thus achieve the effect of reducing wear and preventing blockage.

[0036] Furthermore, the mixing and conveying unit 2 also includes an electronic scale 25 and a level gauge. The electronic scale 25 is installed below the mixing agitator 24, and the level gauge is installed on the hopper 21. On the one hand, the level gauge can maintain the material seal, and on the other hand, the level gauge can roughly estimate the conveying amount of zinc powder. Combined with the electrical control system of the lubricating powder injector 23, the zinc powder falling from the first rotary feeder 22 and the solid lubricating powder can be pre-mixed above the mixing agitator 24 in a certain proportion, and then further mixed by the mixing agitator 24 to obtain the best mixing ratio and achieve the best anti-wear effect. Anti-jamming baffles 261 are installed on both the first rotary feeder 22 and the second rotary feeder 26 to prevent the rotary feeder from jamming when a large amount of material is conveyed. A first pressure sensor 311 and an electric pressure relief valve 312 are installed on the first main classifier 31. The pressure is regulated by the first pressure sensor 311 and the electric pressure relief valve 312 to ensure the stable operation of the dense phase pneumatic conveying process.

[0037] Before the system is put into operation, the nitrogen storage tank 12 must be filled with enough carrier gas to maintain the stable operation of the entire pneumatic conveying system. During operation, the working pressure of the nitrogen storage tank 12 must remain constant. The air compressor 11 can be controlled via the cloud. Before material conveying (i.e., the first rotary feeder 22 is opened), the nitrogen storage tank 12 and the air compressor 11 are opened to fill the entire conveying system with nitrogen, purging and pressurizing the system to prevent moisture and oxygen in the air from reacting with the zinc powder. After the entire conveying system is filled with nitrogen and meets the working pressure, the first rotary feeder 22 is opened, conveying the zinc powder in the hopper 21 to the mixing agitator 24. Simultaneously, the lubricating powder injector 23 evenly sprays lubricating powder onto the mixing agitator 24, pre-mixing the lubricating powder and zinc powder before stirring. After thorough mixing, the second rotary feeder 26 is opened, and the mixture flows out from the second rotary feeder 26 and is guided by the material guide pipe 27 before entering the conveyor. The zinc powder is transported by high-pressure nitrogen through a conveying pipeline. It then enters the first main classifier 31, then the second main classifier 32, and finally the cyclone dust collector 33. The first main classifier 31, the second main classifier 32, and the cyclone dust collector 33 separate zinc powder of different particle sizes and store them separately. A bag filter 34 collects fine solid lubricating powder from the carrier gas, filtering it. The collected lubricating powder is recycled back into the lubricating powder injector 23, reducing solid lubricating powder loss. The outlet of the bag filter 34 is connected to the inlet of the air compressor 11 via a nitrogen outlet pipe 35, allowing the filtered nitrogen to be recycled, reducing air consumption. The air compressor 11 is shut off after the zinc powder transport is complete (i.e., no residual zinc powder remains in the entire transport system) to ensure the safe operation of the transport system.

[0038] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A pneumatic conveying system for zinc powder, characterized in that: include, The air supply unit (1) provides a stable constant pressure air source for the pneumatic conveying system; The mixing and conveying unit (2) is used to mix zinc powder and solid lubricating powder and convey the materials. The graded storage and recovery unit (3) is used for graded storage of zinc powder of different particle sizes and recovery of solid lubricating powder mixed in zinc powder as well as conveying carrier gas; The gas supply unit (1) includes an air compressor (11), a nitrogen storage tank (12), and a high-pressure nitrogen transmission pipe (13). The air inlet of the air compressor (11) is connected to the graded storage and recovery unit (3), the air outlet of the air compressor (11) is connected to the air inlet of the nitrogen storage tank (12) through a pipe, and the air outlet of the nitrogen storage tank (12) is connected to the mixing and conveying unit (2) through the high-pressure nitrogen transmission pipe (13). The mixing and conveying unit (2) includes a hopper (21), a mixing agitator (24), a first rotary feeder (22), a lubricating powder injector (23), a second rotary feeder (26), a material guide pipe (27), and a conveying pipeline. The upper part of the hopper (21) is connected to the condenser in the zinc powder preparation process. The lower part of the hopper (21) is connected to the mixing agitator (24) through the first rotary feeder (22). The lubricating powder injector (23) is symmetrically arranged around the mixing agitator (24). The second rotary feeder (26) is located below the mixing agitator (24). The material guide pipe (27) is located on the second rotary feeder (26). The high-pressure nitrogen gas transmission pipe (13), the conveying pipeline, and the material guide pipe (27) are connected in a three-way configuration. The solid lubricating powder is graphite powder. The graded storage and recycling unit (3) includes a first main classifier (31), a second main classifier (32), a cyclone dust collector (33), a bag dust collector (34), and a nitrogen outlet pipe (35). The inlet end of the first main classifier (31) is connected to the conveying pipeline. The inlet end of the second main classifier (32) is connected to the outlet end of the first main classifier (31). The inlet end of the cyclone dust collector (33) is connected to the outlet end of the second main classifier (32). The inlet end of the bag dust collector (34) is connected to the outlet end of the cyclone dust collector (33). The outlet end of the bag dust collector (34) is connected to the air inlet end of the air compressor (11) through the nitrogen outlet pipe (35).

2. The zinc powder pneumatic conveying system as described in claim 1, characterized in that: The conveying pipeline includes a horizontal conveying pipe (28), a first bend (29), a vertical pipe (210), and a connecting bend (211). The inlet end of the horizontal conveying pipe (28), the outlet end of the material guide pipe (27), and the outlet end of the high-pressure nitrogen conveying pipe (13) are connected in the form of a tee. The inlet end of the first bend (29) is connected to the outlet end of the horizontal conveying pipe (28). The outlet end of the first bend (29) is connected to the inlet end of the vertical pipe (210). The outlet end of the vertical pipe (210) is connected to the inlet end of the connecting bend (211). The outlet end of the connecting bend (211) is connected to the graded storage and recycling unit (3). A spherical chamber (291) is provided inside the first bend (29), and a guide plate (2111) is provided inside the connecting bend (211).

3. The zinc powder pneumatic conveying system as described in claim 1, characterized in that: The mixing and conveying unit (2) also includes an electronic scale (25), which is located below the mixing agitator (24).

4. The zinc powder pneumatic conveying system as described in claim 3, characterized in that: Both the first rotary feeder (22) and the second rotary feeder (26) are equipped with anti-jamming baffles (261).

5. The zinc powder pneumatic conveying system as described in claim 1, characterized in that: The first main classifier (31) is equipped with a first pressure sensor (311) and an electric pressure relief valve (312).

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