An air jet milling system and an air jet milling method thereof

Abstract

The application discloses an air flow crushing system and an air flow crushing method thereof, and belongs to the technical field of material crushing. The air flow crushing system comprises an air flow crusher, a gas-solid separation device, an exhaust fan and a gas supplement fan. The raw material inlet of the air flow crusher is communicated with the air outlet of the gas supplement fan. The powder outlet of the air flow crusher is communicated with the feeding port of the gas-solid separation device. The exhaust port of the gas-solid separation device is communicated with the air inlet of the exhaust fan. The air flow crushing method comprises the following steps: the air flow crusher crushes materials into powder; the powder is discharged into the gas-solid separation device for separation; the exhaust fan draws the gas in the gas-solid separation device out; the gas supplement fan supplements the gas into the air flow crusher; the exhaust fan and the gas supplement fan cooperate to maintain the stable pressure in the air flow crusher, avoid the generation of a large amount of fine powder, timely discharge the powder into the gas-solid separation device, avoid over-crushing, improve the qualified rate and reduce energy loss.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material crushing, in particular to an air flow crushing system and an air flow crushing method thereof. BACKGROUND

[0002] Air flow crushing is a widely used powder processing equipment, which is widely used in battery materials, medicine, food processing and other fields. After hundreds of years of development, it has developed into a powder processing equipment suitable for different fields, including air jet type air flow mill, flat type air flow mill, circulating pipe type air flow mill and fluidized bed type air flow mill. The demand for powder materials is not only the fineness requirement of the material, but also the requirement for the particle size distribution of the material. Because the traditional air flow crushing system generally adopts exhaust fan exhaust method to provide negative pressure state for the crushing chamber to guide the crushed material out, the pressure in the crushing chamber is difficult to maintain stable state, which leads to unstable crushing environment and inevitably produces a large amount of fine powder, resulting in wide particle size distribution. Moreover, many materials cannot be discharged in time after being crushed in the crushing chamber, which leads to over crushing, reduces the qualified rate of powder and causes energy loss. SUMMARY

[0003] The purpose of the present application is to solve the above technical problems, provide an air flow crushing system and an air flow crushing method thereof. The exhaust fan and the air supplementing fan cooperate to maintain the entire air flow crushing system in a stable positive pressure or negative pressure state, provide a stable pressure environment for the crushing chamber of the air flow crusher, so that the air flow crusher can stably crush the material, avoid the generation of a large amount of fine powder, and at the same time, the air supplementing fan can supplement air or increase air supply to timely discharge the material in the air flow crusher, avoid over crushing, improve the qualified rate and reduce energy loss.

[0004] To achieve the above purpose, the present application provides the following scheme: the present application discloses an air flow crushing system, which comprises an air flow crusher, a gas-solid separation device, an exhaust fan and an air supplementing fan. The raw material inlet of the air flow crusher is communicated with the air outlet of the air supplementing fan. The powder outlet of the air flow crusher is communicated with the feeding port of the gas-solid separation device. The exhaust port of the gas-solid separation device is communicated with the air inlet of the exhaust fan.

[0005] Preferably, the gas-solid separation device is a cyclone separator.

[0006] Preferably, it further comprises a dust collector, and the air inlet of the dust collector is communicated with the exhaust port of the gas-solid separation device.

[0007] Preferably, the dust collector is a bag dust collector.

[0008] Preferably, the air outlet of the exhaust fan is communicated with an exhaust pipe, and the air inlet of the air supplementing fan is communicated with the exhaust pipe.

[0009] Preferably, the jet mill is a fluidized bed jet mill.

[0010] Preferably, the air supplementing fan and the air exhausting fan are both positive displacement fans.

[0011] Preferably, the positive displacement fan is a Roots fan.

[0012] Preferably, the air supplementing fan and the air exhausting fan are both controlled by a frequency converter.

[0013] Also disclosed is a jet milling method using the above-mentioned jet milling system, comprising the following steps:

[0014] The jet mill grinds the material into powder, the powder is discharged into the gas-solid separation device for material and gas separation, the air exhausting fan exhausts the gas in the gas-solid separation device, the air supplementing fan supplements the gas into the jet mill, and the air exhausting fan and the air supplementing fan cooperate to maintain the pressure in the jet mill stable, and timely discharge the powder into the gas-solid separation device for powder and gas separation.

[0015] The present application has the following technical effects relative to the prior art:

[0016] In the present application, the air in the entire jet milling system can be exhausted by the air exhausting fan, and the air can be supplemented into the entire jet milling system by the air supplementing fan, and the air exhausting fan and the air supplementing fan cooperate to maintain the entire jet milling system in a stable positive pressure or negative pressure state, to provide a stable pressure environment for the grinding chamber of the jet mill, so that the jet mill can stably grind the material into qualified powder, avoid a large amount of fine powder, and at the same time, during the grinding process of the jet mill, the material in the jet mill can be timely discharged by supplementing air or increasing air supplementing by the air supplementing fan, to avoid over-grinding, improve the qualified rate, and reduce energy loss. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below, and obviously, the drawings in the following description can only be some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0018] Figure 1 It is a structural schematic diagram of the jet milling system in the embodiment.

[0019] Figure 2 It is a SEM electron microscope diagram of the powder collected by using the jet milling system in the embodiment.

[0020] Figure 3 It is a SEM electron microscope diagram of the powder collected by using the traditional jet milling system.

[0021] Explanation of reference numerals in the attached drawings: 1. Air jet mill; 2. Gas-solid separation equipment; 3. Dust collector; 4. Exhaust fan; 5. Exhaust pipe; 6. Make-up air fan. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1

[0024] This embodiment provides an airflow pulverizing system, such as Figures 1 to 3 As shown, the system includes an air jet mill 1, a gas-solid separator 2, an exhaust fan 4, and a supplementary air fan 6. The raw material inlet of the air jet mill 1 is connected to the air outlet of the supplementary air fan 6, the powder outlet of the air jet mill 1 is connected to the feed inlet of the gas-solid separator 2, and the exhaust outlet of the gas-solid separator 2 is connected to the air inlet of the exhaust fan 4.

[0025] Working principle:

[0026] The exhaust fan 4 extracts gas from the entire airflow pulverizing system, while the replenishing fan 6 replenishes gas into the system. The combined operation of these two fans maintains a stable positive or negative pressure within the system, providing a stable pressure environment for the pulverizing chamber of the airflow pulverizer 1. This allows the pulverizer 1 to reliably pulverize materials into powders of the required particle size, preventing the generation of excessive fine powder (particles smaller than the required particle size). Under positive or negative pressure, the pulverized powder is fed into the gas-solid separator 2, where it separates the powder from the gas. The separated powder is discharged from the discharge port of the separator, while the gas is discharged from the exhaust port. During the pulverizing process, replenishing gas via the replenishing fan 6 or increasing the replenishment volume ensures timely removal of properly pulverized material from the pulverizer 1, preventing over-pulverization, improving the yield rate, increasing production efficiency, and reducing energy loss.

[0027] In one implementation, such as Figures 1 to 3As shown, the gas-solid separation device 2 uses a cyclone separator. Of course, this is only one preferred option; other types of gas-solid separation devices can be used if suitable powder and gas separation equipment is available. The cyclone separator mainly consists of a cylindrical volute and a conical collecting section. The bottom of the conical section is the discharge port, which is controlled by a star-shaped discharge valve or a double-disc valve. Since the cyclone separator is existing equipment, it will not be described in detail here.

[0028] In one implementation, such as Figures 1 to 3 As shown, it also includes a dust collector 3, the air inlet of which is connected to the exhaust port of the gas-solid separation device 2 (such as a cyclone separator). The dust collector 3 can intercept and collect the powder that has not been completely separated in the gas discharged from the gas-solid separation device 2, thus preventing the powder from being discharged with the gas and causing a waste of resources.

[0029] In one implementation, such as Figures 1 to 3 As shown, dust collector 3 is a baghouse dust collector. Over time, the permeability of the filter bags in the baghouse dust collector may change, leading to unstable pressure in the pulverizing chamber of the airflow pulverizer 1. In this case, the pressure on both sides of the filter bags can be adjusted by the cooperation of the supplementary air fan 6 and the exhaust fan 4 to prevent pressure instability in the pulverizing chamber of the airflow pulverizer 1. The baghouse dust collector mainly consists of a metal frame, filter bags, and a back-blowing device. The filter bags include, but are not limited to, metal filter bags or woven organic materials. The back-blowing device consists of an air nozzle and an air tank, which stores gas. When back-blowing is needed, all the gas in the air tank is released within 0-1 seconds. The back-blowing pressure includes, but is not limited to, 0-0.5 MPa. Since the baghouse dust collector is existing equipment, it will not be described in detail here.

[0030] In one implementation, such as Figures 1 to 3 As shown, the exhaust fan 4 has an exhaust pipe 5 connected to its outlet, and the inlet of the supplementary air fan 6 is connected to the exhaust pipe 5. This configuration makes the gas discharged by the exhaust fan 4 the gas source for the supplementary air fan 6. The purpose is to make the discharged gas undergo another crushing cycle, so that the materials that are not collected cleanly or not crushed properly in the gas can be crushed and collected again, thus avoiding waste of resources.

[0031] In one implementation, such as Figures 1 to 3As shown, the jet mill 1 is a fluidized bed jet mill. Of course, other forms of jet mill can also be used, such as opposed jet mill, flat jet mill, and circulating tube jet mill. However, the fluidized bed jet mill is more suitable. The crushing chamber of the fluidized bed jet mill is supported by a support, the feeding of the crushing chamber is carried out by a star-shaped feeding valve or a screw feeder or other uniform control feeding mode, the system also controls the uniform feeding of the feeding device by the current or torque of the grading motor, the bottom of the crushing chamber is a symmetrical Laval nozzle, the nozzle is symmetrically distributed, the nozzle is opposite to the central axis, the upper part is composed of a grading wheel for material grading, the Laval nozzle uses gas provided by an air compressor or other pressure gas providing device or equipment, the pressure range includes but is not limited to low pressure, medium pressure, high pressure or super-high pressure gas, and the grading wheel controlled by the frequency converter is a single-head or multi-head grading wheel. Since the fluidized bed jet mill is an existing device, its structure will not be described in detail here.

[0032] In an embodiment, as shown in Figures 1 to 3 The air supplementing fan 6 and the exhaust fan 4 are both volumetric fans.

[0033] In an embodiment, as shown in Figures 1 to 3 The volumetric fan is a Roots fan, and of course other forms of volumetric fan can also be used. However, compared with centrifugal fans, the gas flow of the Roots fan is more stable, thereby stably maintaining the gas in the system, reducing the gas flow resistance, providing a stable crushing environment, and ensuring the stability of the crushing process.

[0034] In an embodiment, as shown in Figures 1 to 3 The air supplementing fan 6 and the exhaust fan 4 are both controlled by a frequency converter.

[0035] In an embodiment, as shown in Figures 1 to 3 The pressure in the crushing chamber of the jet mill 1 is positive or negative, the positive pressure is preferably 0Kpa to 50Kpa, and the negative pressure is preferably -50 to 0Kpa.

[0036] In an embodiment, as shown in Figures 1 to 3 The comparative experiment is carried out as shown in

[0037] Experiment 1: The jet mill 1 adopts a fluidized bed jet mill, the gas-solid separation device 2 adopts a cyclone separator, the dust collector 3 adopts a bag dust collector, the exhaust fan 4 and the air supplementing fan 6 both adopt Roots fans, and an exhaust pipe 5 is provided. The crushing pressure of the fluidized bed jet mill (jet mill 1) is adjusted to 800Kpa, the feeding speed is adjusted to 30Kg / h according to the crushing condition, the rotating speed of the grading wheel of the fluidized bed jet mill is 5000r / min, the air supplementing amount of the air supplementing fan 6 is 500m 3 / h, under this condition, the qualified material received by the cyclone separator (gas-solid separation device 2) is as follows: Figures 1 to 3 The SEM under this condition is shown in the figure.

[0038] Experiment 2: The jet mill 1 adopts a fluidized bed jet mill, the gas-solid separation device 2 adopts a cyclone separator, the dust collector 3 adopts a bag dust collector, the exhaust fan 4 and the air supplement fan 6 both adopt Roots blowers, and an exhaust pipe 5 is arranged. The crushing pressure of the fluidized bed jet mill (jet mill 1) is adjusted to 800 Kpa, the feeding speed is adjusted to 10 Kg / h according to the crushing condition, the speed of the classification wheel of the fluidized bed jet mill is 6000 r / min, the air supplement amount of the air supplement fan 6 is 500 m 3 / h.

[0039] Experiment 3: The jet mill 1 adopts a fluidized bed jet mill, the gas-solid separation device 2 adopts a cyclone separator, the dust collector 3 adopts a bag dust collector, the exhaust fan 4 and the air supplement fan 6 both adopt Roots blowers, and an exhaust pipe 5 is arranged. The crushing pressure of the fluidized bed jet mill (jet mill 1) is adjusted to 800 Kpa, the feeding speed is adjusted to 10 Kg / h according to the crushing condition, the speed of the classification wheel of the fluidized bed jet mill is 4000 r / min, the air supplement amount of the air supplement fan 6 is 300 m 3 / h.

[0040] Experiment 4: The jet mill 1 adopts a fluidized bed jet mill, the gas-solid separation device 2 adopts a cyclone separator, the dust collector 3 adopts a bag dust collector, the exhaust fan 4 adopts a centrifugal fan, and there is no air supplement fan 6.

[0041] The powders obtained in the above experiments 1 to 4 are tested and characterized by particle size test and SEM test:

[0042] Particle size test: 0.2 g of the prepared material is taken in a small beaker, about 50 ml of water is added, and stirred and mixed well, then ultrasonic treatment is carried out in the ultrasonic for 5 minutes, then a pipette is used to add the material into a particle size analyzer for testing, and the particle size curve and results are obtained. The particle size test results are as follows:

[0043] Particle size test table

[0044] Figure 2 Particle size sample 0-2um / % D10 / um D50 / um D90 / um D100 / um 3.42 3.03 5.47 9 13.1 Experiment 1 1.43 3.52 5.69 8.91 12.7 Experiment 2 4.2 2.71 5.52 9.1 13.1 Experiment 3 7.9 1.8 5.49 9.7 13.5

[0045] SEM test: a small amount of material particles are taken on a carbon tape and placed under an electron microscope for SEM scanning to obtain the SEM test results. The results of experiment 1 are shown in the figure. Experiment 4 The results of experiment 4 are shown in the figure. Figure 2

[0046] ​In summary, the fineness and particle size distribution of the powder in experiments 1 to 3 are better than that in experiment 4, because the airflow pulverizing system in experiments 1 to 3 is used.

[0047] Example 2

[0048] This example provides an airflow pulverizing method, as shown in Figure 3 The airflow pulverizing system in example 1 is used, and the method comprises the following steps:

[0049] The airflow pulverizing machine 1 pulverizes the material into powder, and the powder is discharged into the gas-solid separation device 2 for separation of the material and the gas. The exhaust fan 4 quantitatively exhausts the gas in the gas-solid separation device 2, the air supplement fan 6 supplements the gas into the airflow pulverizing machine 1, the exhaust fan 4 and the air supplement fan 6 cooperate to maintain the pressure in the airflow pulverizing machine 1 stable, and the powder is discharged into the gas-solid separation device 2 in time. The gas-solid separation device 2 separates the powder and the gas.

[0050] In an embodiment, as shown in Figures 1 to 3 The pressure in the pulverizing cavity of the airflow pulverizing machine 1 is positive pressure or negative pressure. The positive pressure is preferably 0 Kpa to 50 Kpa, and the negative pressure is preferably -50 to 0 Kpa.

[0051] In an embodiment, as shown in Figures 1 to 3 In pulverization, the entire system has two moving mediums, i.e. the material flow and the gas flow. The material flows into the pulverizing cavity of the fluidized bed airflow pulverizing machine (airflow pulverizing machine 1) through the controllable feeding device, and the gas supplemented by the air supplement fan 6 enters the pulverizing cavity synchronously. The material is pulverized by the shearing force of mutual collision under the action of the opposite moving gas flow in the pulverizing cavity. The particles after collision rise to the classification wheel under the action of the upward gas flow in the pulverizing cavity. The powder with smaller particles is accelerated to a higher speed and passes through the classification wheel. The material with larger particles returns to the pulverizing area due to the smaller speed and is pulverized again. The material separated by the classification wheel is separated from the gas by the volute of the cyclone separator (gas-solid separation device 2). The qualified material is collected, and the gas containing part of the fine powder enters the bag dust collector (dust collector 3). The bag dust collector separates the fine powder from the gas by bag filtration. The fine powder is collected at the bottom of the bag dust collector, and the gas is discharged to the outside through the exhaust pipe 5 after the exhaust fan 4, and part of the gas enters the pulverizing cavity of the fluidized bed airflow pulverizing machine through the exhaust pipe 5 and the air supplement fan 6.

[0052] In an embodiment, as shown in Figures 1 to 3 Figures 1 to 3 The comparative experiment is carried out, and the specific process and results of the comparative experiment are referred to the comparative experiment in example 1.

[0053] The principles and implementation manners of the present application are described by using specific examples in the present application, and the above examples are only used for helping to understand the method of the present application and its core idea; meanwhile, for the general technical personnel in the art, according to the idea of the present application, the specific implementation manners and application ranges will be changed. In conclusion, the content of the present specification should not be understood as the limitation of the present application.

Claims

1. An air jet milling system characterized in that, The system comprises an air flow pulverizer, a gas-solid separation device, an exhaust fan and a gas supplement fan, the raw material inlet of the air flow pulverizer is communicated with the air outlet of the gas supplement fan, the powder outlet of the air flow pulverizer is communicated with the feeding inlet of the gas-solid separation device, the exhaust outlet of the gas-solid separation device is communicated with the air inlet of the exhaust fan, the air flow pulverizer is a fluidized bed type air flow pulverizer, the exhaust fan exhausts the gas in the gas-solid separation device, the gas supplement fan supplements the gas into the air flow pulverizer, the exhaust fan and the gas supplement fan cooperate to maintain the stable pressure in the air flow pulverizer, during the pulverizing process of the air flow pulverizer, the gas supplement of the gas supplement fan is increased, so that the qualified pulverized material in the air flow pulverizer can be discharged in time; the system further comprises a dust collector, the air inlet of the dust collector is communicated with the exhaust outlet of the gas-solid separation device, the air outlet of the dust collector is communicated with the air inlet of the exhaust fan, the air outlet of the exhaust fan is communicated with an exhaust pipe, the air inlet of the gas supplement fan is communicated with the exhaust pipe. The exhaust fan and the gas supplement fan cooperate to maintain the stable pressure in the air flow pulverizer.

2. The jet milling system of claim 1, wherein, The gas-solid separation device is a cyclone separator.

3. The jet milling system of claim 2, wherein, The dust collector is a bag dust collector.

4. The jet milling system of claim 1, wherein, The gas supplement fan and the exhaust fan are both volumetric fans.

5. A jet milling system according to claim 4, wherein, The volumetric fan is a Roots fan.

6. The jet milling system of claim 1, wherein, The gas supplement fan and the exhaust fan are both controlled by a frequency converter.

7. A gas flow pulverization method characterized by, The system adopts the air flow pulverizing system as claimed in any one of claims 1 to 6, and comprises the following steps: The air flow pulverizer pulverizes the material into powder, the powder is discharged into the gas-solid separation device for material and gas separation, the exhaust fan exhausts the gas in the gas-solid separation device, the gas supplement fan supplements the gas into the air flow pulverizer, the exhaust fan and the gas supplement fan cooperate to maintain the stable pressure in the air flow pulverizer, and the powder is discharged into the gas-solid separation device for powder and gas separation in time. The system adopts the air flow pulverizing system as claimed in any one of claims 1 to 6, and comprises the following steps: The air flow pulverizer pulverizes the material into powder, the powder is discharged into the gas-solid separation device for material and gas separation, the exhaust fan exhausts the gas in the gas-solid separation device, the gas supplement fan supplements the gas into the air flow pulverizer, the exhaust fan and the gas supplement fan cooperate to maintain the stable pressure in the air flow pulverizer, and the powder is discharged into the gas-solid separation device for powder and gas separation in time.

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