A metal powder preparation device and a metal powder preparation method

Abstract

The present invention provides a metal powder preparation device and a metal powder preparation method. The metal powder preparation device includes a raw material bin, a screw conveyor, a gas milling bin, a vertical milling bin separation bin, a classification motor and a classification wheel. The outlet of the raw material bin is connected to the inlet of the screw conveyor through a pipeline, and the outlet of the screw conveyor is connected to the feed inlet of the gas milling bin through a pipeline. The outlet of the gas milling bin is connected to the bottom end of the vertical milling bin. High wear-resistant material grinding rods are coaxially arranged in the vertical milling bin. The top end of the vertical milling bin is connected to the inlet of the separation bin through a bent pipe. A separation motor and a classification wheel are arranged at the top of the separation bin, and a discharging mechanism is arranged at the bottom discharging port. The outlet of the discharging mechanism is connected to the return material port of the gas milling bin through a pipeline. When using the preparation device of the present invention to prepare metal powder, the kinetic energy utilization rate of the gas can be greatly improved, the power consumption can be reduced, and thus the preparation cost of the metal powder can be reduced.

Description

Technical Field

[0001] The present invention relates to a metal material crushing device, and in particular to a metal powder preparation device and a method for preparing metal powder, belonging to the technical field of metal powder processing. Background Art

[0002] High-performance metal powder materials are a kind of powder materials directly used by utilizing the inherent physical and chemical characteristics of the materials themselves, and they have high requirements for preparation technology. In the field of metal powder material preparation, air classifiers are often used to prepare fine powders and ultrafine powders.

[0003] In the related art, a Chinese patent document with the publication number CN115888934A discloses a fluidized bed air classifier mill, which includes a support base and a barrel body arranged on the base, a feeding mechanism, an air flow mechanism and a classification mechanism. The inner cavity of the barrel body is divided into an upper cavity and a lower cavity that are vertically connected from top to bottom. The top of the upper cavity and the bottom of the lower cavity are sealed. The air flow mechanism is arranged at the lower part of the lower cavity. A feeding port is arranged in the middle of the lower cavity. The feeding mechanism is arranged outside the barrel body and communicates with the lower cavity of the barrel body through the feeding port. The classification mechanism includes a classification motor, a classification wheel and a discharge part. The classification motor is arranged outside the barrel body. The classification wheel is an alumina ceramic classification wheel and is arranged above the connection between the upper cavity and the lower cavity in the barrel body. One end of the classification wheel is connected to the transmission shaft of the classification motor, and the other end communicates with the discharge part. A sealing disc with a positive pressure air structure is arranged between the classification wheel and the discharge part.

[0004] In the fluidized bed air classifier mill in the related art, after the material is added, the high-speed air flow carries the solid particles for a primary impact, and then the gas moves upward and is discharged from the device through the classification wheel. In this process, the gas fails to effectively utilize the kinetic energy of the air flow, losing a large part of the energy, resulting in low energy utilization rate. In addition, among the solid particles after impact, many large particles are also sucked into the classification wheel for separation. The entry of large particle materials into the classification wheel for separation increases its load, resulting in high power consumption. At the same time, the wear of the large particles on the classification wheel is relatively large, thus greatly shortening the service life of the device.

[0005] Therefore, there is an urgent need for a metal powder preparation device Summary of the Invention

[0006] The object of the present invention is to address the problems of existing metal powder preparation equipment, where the kinetic energy of high-speed air flow is not fully utilized, resulting in high power consumption and high production costs of the powder; large particles wear the classification wheel, greatly shortening the service life of the equipment. A metal powder preparation device is proposed. This device can achieve efficient energy utilization, thereby reducing the processing cost of metal powder; at the same time, it can effectively reduce equipment wear and extend the service life of the equipment. The metal powder preparation device of the present invention can be widely applied to the preparation of metal powders such as iron powder, aluminum powder, and copper powder.

[0007] It should be noted that in the present invention, unless otherwise specified, the specific meaning of "including" involving compositional limitations and descriptions includes both the open "including", "containing", and their similar meanings, as well as the closed "consisting of", "constituted by", and their similar meanings.

[0008] To achieve the above object, the technical solution adopted by the present invention is: a metal powder preparation device, including: a raw material bin, a screw conveyor, a gas milling bin, a vertical milling bin, a separation bin, a classification motor, and a classification wheel;

[0009] The outlet of the raw material bin is connected to the inlet of the screw conveyor through a pipeline, the outlet of the screw conveyor is connected to the feed inlet of the gas milling bin through a feed pipe, a first flap valve is arranged at the feed inlet of the gas milling bin, the outlet of the gas milling bin is connected to the bottom end of the vertical milling bin, and the central axes of the gas milling bin and the vertical milling bin are the same and perpendicular to the ground; a plurality of supersonic nozzles are uniformly arranged along the inner wall circumference (annular) of the lower part of the gas milling bin, and the air flows ejected by the plurality of supersonic nozzles point to the same center; the supersonic nozzles are externally connected to a nitrogen gas source;

[0010] The vertical milling bin includes a vertically arranged bin cylinder and grinding rods located inside the bin cylinder, and the bin cylinder and the grinding rods are coaxially arranged; the top end of the bin cylinder is connected to the inlet of the separation bin through a bent pipe, and the section of the bent pipe connected to the inlet of the separation bin is a horizontal pipe section.

[0011] The upper part of the separation bin is a cylindrical section, and the lower part is a conical section. The side wall of the cylindrical section is provided with an inlet of the separation bin; a target plate is vertically arranged at the top inside the separation bin, and the target plate is perpendicular to the inlet of the separation bin. The target plate divides the upper part of the separation bin into two spaces, and the bottoms of the two spaces are connected; the lower edge of the target plate is lower than the lower edge of the inlet of the separation bin, and the area of the extended surface (extended to the bottom of the separation bin) of the target plate is 10 - 40 times the cross-sectional area of the inlet of the separation bin; a separation motor is arranged above the separation bin, a classification wheel is arranged at the top inside the separation bin, and the classification wheel and the inlet of the separation bin are respectively located on both sides of the target plate. The separation motor is rotationally connected to the classification wheel; the outlet of the classification wheel is connected to the product outlet of the separation bin; the discharge port at the bottom of the separation bin is connected to the return port of the gas milling bin through a return pipe, and a second flap valve is arranged at the return port of the gas milling bin.

[0012] Furthermore, a feed loosening air nozzle is arranged inside the feed pipe of the air mill bin near the first flap valve, and the distance from the feed loosening air nozzle to the first flap valve is 0.3 - 0.8 meters. The feed loosening air nozzle can effectively loosen the powder material and prevent blockage during the material flow process.

[0013] Furthermore, a return material loosening air nozzle is arranged inside the return material pipe of the air mill bin near the second flap valve, and the distance from the return material loosening air nozzle to the second flap valve is 0.3 - 0.8 meters. The return material loosening air nozzle can effectively loosen the powder material and prevent blockage during the material flow process.

[0014] Furthermore, the lower edge of the target plate is 0.5 - 1.5 meters lower than the lower edge of the separation bin inlet.

[0015] Furthermore, the air mill bin is provided with a highly wear-resistant lining, and the highly wear-resistant lining includes but is not limited to zirconia or alumina ceramics.

[0016] Furthermore, the number of the supersonic nozzles is 6 - 12.

[0017] Furthermore, both the inner surface of the bin cylinder and the outer surface of the grinding rod are provided with highly wear-resistant materials with rough surfaces, and the highly wear-resistant materials include but are not limited to tungsten carbide.

[0018] Furthermore, the diameter of the grinding rod is 0.5 - 0.8 times the inner diameter of the bin cylinder, and the grinding rod is fixedly connected to the inner wall of the bin cylinder through a bracket.

[0019] Furthermore, the lower part of the grinding rod is a cone, and the cone is coaxial with the grinding rod, which is beneficial to the uniform dispersion of the rising mixed flow and reduces the resistance.

[0020] Furthermore, a plurality of fins are uniformly arranged on the outer wall of the grinding rod, preferably 4 - 8 fins; the length of the fins is the same as the length of the cylindrical section of the grinding rod, that is, both ends of the fins are aligned with both ends of the cylindrical section of the grinding rod, which can effectively increase the contact area between the material and the grinding rod and improve the grinding effect.

[0021] Furthermore, the upper end and the left and right ends of the target plate are fixedly connected to the inner wall of the separation bin through bolts.

[0022] Furthermore, the distance between the target plate and the separation bin inlet is 0.5 - 1 meter.

[0023] Furthermore, the classifier wheel is a zirconia ceramic classifier wheel or an alumina ceramic classifier wheel.

[0024] Furthermore, a star-shaped discharger or a screw discharger is arranged at the bottom discharge port of the separation bin, and the outlet of the star-shaped discharger or the screw discharger is connected to the return material port of the air mill bin through a return material pipe.

[0025] Furthermore, the return material port of the air mill bin is located on the side opposite to the feed port of the air mill bin.

[0026] Furthermore, a plurality of separation bin loosening air nozzles are uniformly arranged along the circumferential direction (annular shape) of the inner wall at the lower part of the separation bin.

[0027] Furthermore, the number of the separation bin loosening air nozzles is 4 - 8.

[0028] Furthermore, the metal powder preparation device further includes a screw conveyor jacket, a liquid nitrogen evaporator, and a compressor. The jacket outlet of the screw conveyor jacket is connected to the inlet of the liquid nitrogen evaporator through a pipeline; the outlet of the liquid nitrogen evaporator is connected to the inlet of the compressor through a pipeline; the outlet of the compressor is connected to a supersonic nozzle through a pipeline.

[0029] Furthermore, the liquid nitrogen evaporator is one of an air heat exchanger, an electric heating heat exchanger, a gas - liquid heat exchanger, or a liquid - liquid heat exchanger.

[0030] Furthermore, the metal powder preparation device further includes a control system, and the control system is communicatively connected to the feed loosening air nozzle, the return material loosening air nozzle, the supersonic nozzle, the separation bin loosening air nozzle, the separation motor, and the screw conveyor respectively.

[0031] Another object of the present invention also discloses a method for preparing metal powder, which includes the following steps:

[0032] Step 1: The metal particle material in the raw material bin is transported into the air mill bin through a screw conveyor.

[0033] Step 2: Compressed nitrogen is sprayed into the cavity of the air mill bin at supersonic speed through a plurality of supersonic nozzles arranged at the lower part of the air mill bin, driving the metal particle material in the cavity to collide and crush.

[0034] Step 3: The small particle material obtained by crushing rises with the air flow to the vertical grinding bin for further grinding.

[0035] Step 4: The mixture of the crushed material and the nitrogen gas flow leaves the vertical grinding bin and enters the separation bin. After the gas velocity of the mixture flow decreases after entering the separation bin and impacts with the target plate, some particles are further crushed. After passing over the lower edge of the target plate, the metal powder (qualified metal powder) that meets the product requirement particle size and some metal particles (unqualified metal particles) that do not meet the product requirement particle size are separated by a grading wheel. The qualified metal powder is sent out of the device through the product outlet; the unqualified metal particles fall to the bottom of the separation bin.

[0036] After the metal particle material of the present invention is ground at high speed in the air mill bin, it is carried by the air flow into the vertical grinding bin for further grinding, and the qualified product metal powder is separated in the separation bin. The unqualified metal particles are returned to the air mill bin through the return pipe for continuous grinding.

[0037] Further, the metal particle material in the raw material bin described in Step 1 is conveyed to the feed pipe of the air mill bin by a screw conveyor. When the weight of the metal particle material in the feed pipe reaches the set discharge weight value, the first flap valve at the feed inlet of the air mill bin automatically opens, and the metal particle material enters the air mill bin; when the material in the feed pipe does not reach the discharge weight, the first flap valve closes under the action of gravity, effectively preventing nitrogen from entering the feed pipe of the air mill bin.

[0038] Further, in Step 2, liquid nitrogen enters the jacket of the screw conveyor from the jacket inlet of the screw conveyor to cool the metal particles flowing through the screw conveyor. The liquid nitrogen evaporates completely into nitrogen gas from the jacket outlet of the screw conveyor jacket and enters the liquid nitrogen evaporator through a pipeline. The nitrogen gas is compressed by a compressor to reach the design pressure, and the compressed nitrogen gas is sprayed into the cavity of the air mill bin at supersonic speed through a nitrogen pipeline and a supersonic nozzle, driving the metal particle material in the cavity to collide and crush.

[0039] Further, in Step 3, the small particle material obtained by crushing rises with the air flow to the vertical grinding bin. The small particles move vertically upward at high speed, and friction occurs between the particles and between the particles and the grinding rods, achieving the effect of further grinding.

[0040] Further, in Step 4, the pulverized material and nitrogen mixture flow leaves the vertical grinding bin and enters the separation bin horizontally through a bent pipe. Since the area of the extended surface of the target plate (extended to the bottom of the separation bin) is 10 - 40 times the cross-sectional area of the inlet of the separation bin, the gas velocity of the mixture flow decreases to 1 / 10 - 1 / 40 of the original velocity after entering the separation bin. After hitting the target plate, some particles are further pulverized, and the flow direction of the mixture flow changes to from top to bottom. After passing over the lower edge of the target plate, the metal powder that meets the product requirement particle size and the metal particles that do not meet the product requirement particle size are separated by a classifier wheel. The qualified metal powder is sent out of the device through the product outlet; the unqualified metal particles settle under the action of gravity and inertia, and the unqualified metal particles fall to the bottom of the separation bin.

[0041] Further, in Step 4, separation bin loosening air nozzles are evenly arranged circumferentially (in a ring shape) at the lower part of the separation bin. The separation bin loosening air nozzles can loosen the accumulated material and can also adjust the upward air volume of the separation bin to control the particle size distribution of the metal particles entering the classifier wheel.

[0042] Further, in Step 4, the unqualified metal particles recovered at the bottom of the separation bin are sent back to the air mill bin through a star-shaped discharger and a return pipe for continuous crushing and grinding. The second flap valve at the return port of the air mill bin automatically opens when the material in the feed pipe reaches the discharge weight, and closes under the action of gravity when the material in the return pipe does not reach the discharge weight, effectively preventing nitrogen from entering the return pipe.

[0043] The metal powder preparation device of the present invention has a simple, reasonable and compact structure and has the following advantages compared with the prior art:

[0044] 1) A vertical grinding chamber is arranged at the top of the air grinding chamber (air flow pulverizer) of the metal powder preparation device of the present invention. High-speed gas flows through the vertical grinding chamber to form turbulence, and the metal particles are further ground, thereby making fuller use of the kinetic energy of the gas. In addition, the crushing of the metal particles in the air grinding chamber is mainly achieved by the impact of the high-speed air flow and the mutual collision between the metal particles. This crushing method often causes the metal particles to form irregular fracture surfaces when they are broken, thereby generating edges and corners. The vertical grinding chamber can cause the powder to rub against the grinding rod at high speed, making the surface of the metal particles more regular.

[0045] 2) The present invention is also provided with a separation bin, so that most of the large-size metal particles can settle by gravity in the separation bin, thereby effectively reducing the workload of the classifying wheel. The number of large-size metal particles entering the classifying wheel is greatly reduced, which can reduce the wear of the classifying wheel and significantly improve the service life of the classifying wheel.

[0046] 3) The metal particles in the metal powder preparation device of the present invention adopt a solid circulation method of circulating inside the air mill bin and circulating outside the separation bin. After the raw materials are crushed once, the large particles do not reach the carry-out particle size, so they stay in the air mill bin for circulation and crushing; the particles that reach the carry-out particle size but do not reach the required particle size of the product are returned to the return port of the air mill bin via the separation bin. The direction of movement of this stream of material is from top to bottom, which is consistent with the direction of the circulating material at this position in the air mill bin. Therefore, it is beneficial to improve the stability of the material circulation in the air mill bin and further improve the crushing and powder making efficiency.

[0047] 4) The metal powder preparation device of the present invention also includes a screw conveyor jacket. Liquid nitrogen flows through the screw conveyor jacket to significantly reduce the temperature of the metal particles in the screw conveyor. The brittleness of many types of metals is significantly enhanced after the temperature is reduced, which is beneficial to the crushing and powdering of metal particles in the air mill bin, especially for some metals with strong ductility at room temperature. They are not easy to crush at room temperature, and the crushing effect and efficiency can be greatly improved after cooling with liquid nitrogen.

[0048] 5) The metal powder preparation device of the present invention uses nitrogen as the power gas, which eliminates the risk of explosion during the grinding process of ultrafine metal powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic diagram of a metal powder preparation device;

[0050] Figure 2 A schematic diagram of a metal powder preparation device with a liquid nitrogen cooling system;

[0051] Figure 3 This is a top view of the grinding rod cross section.

[0052] Among them, 1. raw material bin; 2. screw conveyor; 3. screw conveyor jacket; 4. jacket inlet; 5. jacket outlet; 6. liquid nitrogen evaporator; 7. compressor; 8. air mill bin; 9. supersonic nozzle; 10. first wing valve; 11. feed loosening air nozzle; 12. second wing valve; 13. return material loosening air nozzle; 14. vertical grinding bin; 15. grinding rod; 16. elbow; 17. separation bin; 18. target plate; 19. separation motor; 20. alumina ceramic classification wheel; 21. product outlet; 22. separation bin loosening air nozzle; 23. star-shaped discharger; 24. nitrogen pipeline; 25. fin. Specific implementation manners

[0053] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0054] In the description of the present application, it should be noted that, unless otherwise clearly defined and limited, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, and can be the connection inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations. In the description of the present application, "a plurality of" means two or more, unless otherwise clearly specifically defined. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more features.

[0055] The following disclosure provides many different implementation manners or examples for implementing different structures of the present application. To simplify the disclosure of the present application, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present application.

[0056] Embodiment 1

[0057] As Figure 1 shown, this embodiment discloses a metal powder preparation device, including: raw material bin 1, screw conveyor 2, air mill bin 8, vertical grinding bin 14, separation bin 17, classification motor 19, alumina ceramic classification wheel 20 and control system.

[0058] The raw material bin 1 is used to store metal particles to be processed. The outlet of the raw material bin 1 is connected to the inlet of the screw conveyor 2 through a pipeline, and the outlet of the screw conveyor 2 is connected to the feed inlet of the air mill bin 8 through a feed pipe. The air mill bin 8 is provided with a highly wear-resistant lining, and the highly wear-resistant lining is zirconia ceramics. A first wing valve 10 is arranged at the feed inlet of the air mill bin 8. The outlet of the air mill bin 8 is connected to the bottom end of the vertical grinding bin 14. The air mill bin 8 and the vertical grinding bin 14 have the same central axis and are perpendicular to the ground. Six supersonic nozzles 9 are evenly arranged along the inner wall circumference (annular) of the lower part of the air mill bin 8, and the air flows ejected by the six supersonic nozzles 9 point to the same center of the circle. The supersonic nozzle 9 is externally connected to a nitrogen gas source.

[0059] The vertical grinding bin 14 includes a vertically arranged bin cylinder and grinding rods 15 located inside the bin cylinder. The bin cylinder and the grinding rods 15 are coaxially arranged. The inner surface of the bin cylinder and the outer surface of the grinding rods 15 are both provided with highly wear-resistant materials with rough surfaces. The highly wear-resistant materials include, but are not limited to, tungsten carbide. The diameter of the grinding rod 15 is 0.6 times the inner diameter of the bin cylinder. The grinding rod 15 is fixedly connected to the inner wall of the bin cylinder through a bracket. The lower part of the grinding rod 15 is a cone, and the cone is coaxial with the grinding rod 15, which is beneficial to the uniform dispersion of the rising mixed flow and reduces the resistance. As Figure 3 shown, eight fins 25 are evenly arranged on the outer wall of the grinding rod 15. The length of the fins 25 is the same as the length of the cylindrical section of the grinding rod 15, that is, the two ends of the fins 25 are respectively aligned with the two ends of the cylindrical section of the grinding rod 15, which can effectively increase the contact area between the material and the grinding rod 15 and improve the grinding effect. The top end of the bin cylinder is connected to the inlet of the separation bin 17 through a bent pipe 16, and the section of the bent pipe 16 connected to the inlet of the separation bin 17 is a horizontal pipe section.

[0060] The upper part of the separation bin 17 is a cylindrical section, and the lower part is a conical section. An inlet of the separation bin 17 is provided on the side wall of the cylindrical section. A target plate 18 is vertically arranged at the top inside the separation bin 17. The target plate 18 is perpendicular to the inlet of the separation bin 17. The target plate 18 divides the upper part of the separation bin 17 into two spaces, and the bottoms of the two spaces are communicated. The lower edge of the target plate 18 is 1 meter lower than the lower edge of the inlet of the separation bin 17. The area of the extended surface of the target plate 18 (extended to the bottom of the separation bin 17) is 40 times the cross-sectional area of the inlet of the separation bin 17. The upper end and the left and right ends of the target plate 18 are fixed to the inner wall of the separation bin 17 by bolts. The distance between the target plate 18 and the inlet of the separation bin 17 is 0.5 meter. A separation motor 19 is arranged above the separation bin 17. A classification wheel 20 is arranged at the top inside the separation bin 17, and the classification wheel 20 and the inlet of the separation bin 17 are respectively located on both sides of the target plate 18. The separation motor 19 is rotationally connected to the classification wheel 20; the classification wheel 20 is an alumina ceramic classification wheel. The outlet of the classification wheel 20 is communicated with the product outlet 21 of the separation bin 17. A star-shaped discharger 23 is arranged at the bottom discharge port of the separation bin 17. The outlet of the star-shaped discharger 23 is communicated with the return port of the air mill bin 8 through a return pipe. The return port of the air mill bin 8 is located on the side opposite to the feed port of the air mill bin 8 and is provided with a second wing valve 12. Four separation bin loosening air nozzles 22 are uniformly arranged along the circumference at the lower part of the separation bin 17. The separation bin loosening air nozzles 22 are communicated with a nitrogen gas source.

[0061] An inlet loosening air nozzle 11 is arranged in the feed pipe of the air mill bin 8 near the first wing valve 10. The distance from the inlet loosening air nozzle 11 to the first wing valve 10 is 0.3 meter; a return loosening air nozzle 13 is arranged in the return pipe of the air mill bin 8 near the second wing valve 12. The distance from the return loosening air nozzle 13 to the second wing valve 12 is 0.3 meter. The inlet loosening air nozzle 11 and the return loosening air nozzle 13 can effectively loosen the powder material and prevent blockage during the flow of the material. The inlet loosening air nozzle 11 and the return loosening air nozzle 13 are respectively communicated with a nitrogen gas source.

[0062] The control system is respectively in communication connection with the inlet loosening air nozzle 11, the return loosening air nozzle 13, the supersonic nozzle 9, the separation bin loosening air nozzles 22, the separation motor 19 and the screw conveyor 2 to control their starting and stopping.

[0063] Taking the preparation of iron powder as an example, the preparation steps are as follows:

[0064] The iron particle material (particle size 0.5 mm - 1.5 mm) in the raw material bin 1 is conveyed to the feed pipe in the air mill bin 8 by the screw conveyor 2 at a feed rate of 80 kg / h. When the weight of the metal particle material in the feed pipe reaches the set discharge weight value, the first flap valve 10 provided at the feed inlet of the air mill bin 8 automatically opens, and the iron particle material enters the air mill bin 8; when the material in the feed pipe does not reach the discharge weight, the first flap valve 10 closes under the action of gravity, effectively preventing nitrogen from flowing into the feed pipe;

[0065] Low-temperature compressed nitrogen at -50 °C enters the cavity of the air mill bin 8 through a plurality of supersonic nozzles 9 with Laval curve-shaped holes provided at the lower part of the air mill bin 8 at a jet speed of Mach 3, driving the iron particles in the cavity to collide and crush at high speed;

[0066] The small particle material obtained after crushing rises with the air flow to the vertical grinding bin 14. The small particles move vertically upward at high speed, and friction occurs between the particles and between the particles and the grinding rods 15, achieving the effect of further grinding;

[0067] After the crushed material and nitrogen mixture flow leave the vertical grinding bin 14, they enter the separation bin 17 horizontally through the elbow 16. Since the area of the extended surface (extended to the bottom of the separation bin 17) of the target plate 18 is 40 times the cross-sectional area of the inlet of the separation bin 17, the gas velocity of the mixture flow drops to 1 / 40 of the original flow velocity after entering the separation bin 17. After hitting the target plate 18, some particles are further crushed, and the flow direction of the mixture flow changes to from top to bottom. The iron powder (particle size 3 μm - 30 μm) that meets the product requirements and some iron particles that do not meet the product requirements are separated by the grading wheel 20. The qualified iron powder is sent out of the device through the product outlet 21; the unqualified iron particles settle under the action of gravity and inertia and fall to the bottom of the separation bin 17.

[0068] Separation bin loosening air nozzles 22 are annularly arranged at the lower part of the separation bin 17, which can loosen the accumulated material and at the same time can adjust the upward gas volume of the separation bin 17 to control the particle size distribution of the iron particles entering the grading wheel 20. The unqualified iron particles recovered at the lower part of the separation bin 17 are sent back to the air mill bin 8 through the star-shaped discharger 23 and the return pipe for continuous crushing and grinding. The second flap valve 12 at the return port of the air mill bin 8 automatically opens when the material in the feed pipe reaches the discharge weight, and closes under the action of gravity when the material in the return pipe does not reach the discharge weight, effectively preventing nitrogen from flowing into the return pipe.

[0069] Example 2

[0070] As Figure 2As shown in the figure, this embodiment discloses a metal powder preparation device, which is basically the same as that of Embodiment 1. The difference is that the device further includes a screw conveyor jacket 3, a liquid nitrogen evaporator 6 and a compressor 7. The jacket inlet 4 of the screw conveyor jacket 3 is communicated with a liquid nitrogen source. The jacket outlet 5 of the screw conveyor jacket 3 is connected to the inlet of the liquid nitrogen evaporator 6 through a pipeline. The outlet of the liquid nitrogen evaporator 6 is connected to the inlet of the compressor 7 through a pipeline. The outlet of the compressor 7 is connected to a nitrogen pipeline 24.

[0071] Liquid nitrogen enters the screw conveyor jacket 3 from the jacket inlet 4 to cool the metal particles flowing through the screw conveyor 2. The liquid nitrogen evaporates completely into nitrogen gas from the jacket outlet 5 and enters the liquid nitrogen evaporator 6 through a pipeline. After being compressed by the compressor 7 to reach the designed pressure, it is connected to the supersonic nozzle 9 through the nitrogen pipeline 24.

[0072] The liquid nitrogen evaporator 6 can be one of an air heat exchanger, an electric heating heat exchanger, a gas-liquid heat exchanger or a liquid-liquid heat exchanger.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A metal powder preparation device, characterized in that: include: A raw material bin (1), a screw conveyor (2), an air grinding bin (8), a vertical grinding bin (14), a separation bin (17), a classifying motor (19) and a classifying wheel (20); The outlet of the raw material bin (1) is connected to the inlet of the screw conveyor (2) through a pipeline, the outlet of the screw conveyor (2) is connected to the feed port of the air mill bin (8) through a feed pipe, a first wing valve (10) is provided at the feed port of the air mill bin (8), the outlet of the air mill bin (8) is connected to the bottom end of the vertical mill bin (14), the central axis of the air mill bin (8) and the vertical mill bin (14) are the same and perpendicular to the ground; a plurality of supersonic nozzles (9) are evenly arranged along the circumference of the inner wall at the lower part of the air mill bin (8), the air flows ejected by the plurality of supersonic nozzles (9) are directed to the same center of a circle; the supersonic nozzles (9) are externally connected to a nitrogen gas source; The vertical grinding bin (14) comprises a vertically arranged bin tube and a grinding rod (15) located in the bin tube, wherein the bin tube and the grinding rod (15) are arranged coaxially; the top end of the bin tube is connected to the inlet of the separation bin (17) via a curved pipe (16), and the connecting section of the curved pipe (16) and the inlet of the separation bin (17) is a horizontal pipe section; The upper portion of the separation chamber (17) is a cylindrical section, and the lower portion is a conical section, and the side wall of the cylindrical section is provided with an entrance to the separation chamber (17); a target plate (18) is vertically arranged at the top of the inner side of the separation chamber (17), and the target plate (18) is perpendicular to the entrance to the separation chamber (17); the target plate (18) divides the upper portion of the separation chamber (17) into two spaces, and the bottoms of the two spaces are connected; the lower edge of the target plate (18) is lower than the lower edge of the entrance to the separation chamber (17); the area of ​​the extended surface of the target plate (18) is 10-40 times the cross-sectional area of ​​the entrance to the separation chamber (17); A grading motor (19) is arranged above the separation bin (17); a grading wheel (20) is arranged at the top of the inner side of the separation bin (17); the grading wheel (20) and the entrance of the separation bin (17) are respectively located on both sides of the target plate (18); the grading motor (19) is rotatably connected to the grading wheel (20); the outlet of the grading wheel (20) is connected to the product outlet (21) of the separation bin (17); the discharge port at the bottom of the separation bin (17) is connected to the return port of the air mill bin (8) through a return pipe; and a second wing valve (12) is arranged at the return port of the air mill bin (8).

2. The metal powder preparation device according to claim 1, characterized in that: A feed loosening air nozzle (11) is provided in the feed pipe of the air mill bin (8) near the first wing valve (10), and the distance between the feed loosening air nozzle (11) and the first wing valve (10) is 0.3-0.8 meters; And / or, a return material loosening air nozzle (13) is provided in the return material pipe of the air mill bin (8) near the second wing valve (12), and the distance between the return material loosening air nozzle (13) and the second wing valve (12) is 0.3-0.8 meters.

3. The metal powder preparation device according to claim 1, characterized in that: The gas mill chamber (8) is provided with a high wear-resistant lining, wherein the high wear-resistant lining is zirconium oxide or aluminum oxide ceramic; And / or, the inner surface of the silo and the outer surface of the grinding rod (15) are both provided with a rough surface high wear-resistant material, and the high wear-resistant material is tungsten carbide.

4. The metal powder preparation device according to claim 1, characterized in that: The diameter of the grinding rod (15) is 0.5-0.8 times the inner diameter of the silo; And / or, the lower part of the grinding rod (15) is a cone, and the cone is coaxial with the grinding rod (15); And / or, a plurality of fins (25) are evenly arranged on the outer wall of the grinding rod (15), and the length of the fins (25) is the same as the length of the cylindrical section of the grinding rod (15).

5. The metal powder preparation device according to claim 1, characterized in that: A plurality of separation bin loosening air nozzles (22) are evenly arranged along the circumference of the inner wall at the lower portion of the separation bin (17).

6. The metal powder preparation device according to claim 1, characterized in that: It also includes a screw conveyor jacket, a liquid nitrogen evaporator and a compressor, wherein the jacket outlet of the screw conveyor jacket is connected to the inlet of the liquid nitrogen evaporator through a pipeline; the outlet of the liquid nitrogen evaporator is connected to the inlet of the compressor through a pipeline; and the outlet of the compressor is connected to the supersonic nozzle (9) through a pipeline.

7. The metal powder preparation device according to claim 1, characterized in that: It also includes a control system, which is communicatively connected to the feed loosening air nozzle (11), the return loosening air nozzle (13), the supersonic nozzle (9), the separation bin loosening air nozzle (22), the grading motor (19) and the screw conveyor (2).

8. A method for preparing metal powder, characterized in that: The metal powder preparation device according to any one of claims 1 to 7 comprises the following steps: Step 1: The metal particle material in the raw material bin (1) is transported to the air grinding bin (8) via a screw conveyor (2); Step 2: compressed nitrogen is injected into the cavity of the air mill (8) at a supersonic speed through a plurality of supersonic nozzles (9) arranged at the bottom of the air mill (8), thereby driving the metal particles in the cavity to collide and crush; Step 3, the small particles obtained by crushing rise with the air flow to the vertical grinding chamber (14) for further grinding; Step 4: The mixed flow of the crushed material and nitrogen leaves the vertical grinding chamber (14) and enters the separation chamber (17). After the mixed flow enters the separation chamber (17), the gas velocity decreases. After colliding with the target plate (18), some particles are further crushed. After crossing the lower edge of the target plate (18), the metal powders that meet the particle size required by the product and some metal particles that do not meet the particle size required by the product are separated by the classification wheel (20). The qualified metal powders are sent out of the device through the product outlet (21); and the unqualified metal particles fall into the bottom of the separation chamber (17).

9. The method for preparing metal powder according to claim 8, characterized in that: In step 1, the metal particle material in the raw material bin (1) is conveyed to the feed pipe of the air mill bin (8) through the screw conveyor (2); when the weight of the metal particle material in the feed pipe reaches a set discharge weight, the first wing valve (10) arranged at the feed port of the air mill bin (8) automatically opens, and the metal particle material enters the air mill bin (8); when the material in the feed pipe does not reach the discharge weight, the first wing valve (10) closes under the action of gravity; And / or, the unqualified metal particles recovered from the bottom of the separation bin (17) in step 4 are sent back to the air mill bin (8) through the star-shaped discharger (23) and the return pipe for further crushing and grinding, and the second wing valve (12) at the return port of the air mill bin (8) automatically opens when the material in the feed pipe reaches the discharge weight, and the second wing valve (12) closes under the action of gravity when the material in the return pipe does not reach the discharge weight.

10. The method for preparing metal powder according to claim 8, characterized in that: Step 4: Separation bin loosening air nozzles (22) are evenly arranged along the circumferential direction at the lower part of the separation bin (17).

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