Brown corundum particle size screening device and screening method

Abstract

A brown corundum particle size screening device and screening method, including feeding equipment and particle size screening mechanism, the feeding equipment is arranged above the particle size screening mechanism, the particle size screening mechanism is provided with a shell structure, the first screen structure, the second screen structure and the third screen structure are sequentially arranged from top to bottom in the shell structure, the discharge port is provided with a layered discharge mechanism, the layered discharge mechanism is provided with a first discharge channel, a second discharge channel and a third discharge channel, a half-section screen structure is further arranged above the first screen structure, the half-section screen structure is installed on the shell structure, the side edge of the half-section screen structure is aligned above the first discharge channel, the feeding equipment is aligned with the half-section screen structure, and the mesh number of the half-section screen structure is more than that of the first screen structure, and a vibrating mechanism is further arranged on the shell structure.The application can adjust the particle size distribution and content proportion of the required brown corundum product, save the process and screening cost, and ensure the product quality.

Description

Technical Field

[0001] This invention relates to the technical field of particle size screening, and specifically to a brown fused alumina particle size screening device and screening method. Background Technology

[0002] Brown fused alumina, also known as corundum, is a brownish-red synthetic corundum produced by melting and reducing bauxite, carbon materials, and iron filings in an electric arc furnace. It is then pulverized and shaped using an autogenous mill, magnetically separated to remove iron, and sieved into various particle sizes. It is characterized by high purity, good crystallinity, strong fluidity, low expansion coefficient, and corrosion resistance. Brown fused alumina can be classified into four types according to particle size: segmented alumina, fine alumina, micro powder, and fine powder. Segmented alumina commonly has particle sizes of 0-1mm, 1-3mm, 3-5mm, 5-8mm, and 8-12mm, and is generally used for rough sandblasting and polishing of workpieces. There are several methods for classifying the particle size of brown fused alumina, including sieving and sedimentation. Currently, sieving is the most commonly used method. Sieving involves using a sieve (screen) to sieve the material. The number of meshes on the sieve is called the mesh size. 50 mesh means there are 50 meshes per square inch, and 100 mesh means there are 100 meshes. The larger the mesh number, the more meshes there are, which means the smaller the particle size. The brown fused alumina particle size obtained by sieving is usually such that the content of different particle sizes of brown fused alumina is roughly the same and the distribution is uniform within the particle size range of the sieve. However, in some cases, it is necessary to obtain a brown fused alumina product with a higher content of a certain particle size within the same particle size range, and with uniform distribution. For example, in the range of 5-8mm particle size of sand, it is necessary to obtain brown fused alumina products with a particle size of 6-8mm accounting for about 70%, and brown fused alumina products with a particle size of 5-6mm accounting for about 30%, and to naturally and uniformly mix them into brown fused alumina products with a particle size of 5-8mm. Currently, it is difficult to achieve this by sieving alone. If it is divided into two particle size ranges, sieved separately, and then mixed in proportion, it not only adds many processes and increases the sieving cost, but also makes it difficult to achieve natural and uniform mixing. In addition, brown fused alumina is prone to breakage during large-scale mixing, which changes the particle size of brown fused alumina and results in a large number of unqualified brown fused alumina products that are not within the particle size range of 5-8mm.

[0003] In the prior art, patent document CN 108940813 A discloses a brown fused alumina vibrating screen. The vibrating screen includes a screen body, with an inclined motor base fixedly installed at an inclined position at the bottom of the screen body. A motor is mounted on the motor base, and the motor's rotational motion drives the brown fused alumina particles on the screen body to move horizontally towards the discharge port and to reciprocate vertically. This solution modifies the structure of the existing vibrating screen plates and the connection method of each layer of screen plates, thereby correspondingly changing the structure of the screen frame head and the screen body. This allows the improved vibrating screen to not only match screen plates required for screening multiple specifications of brown fused alumina, but also improves the interchangeability and versatility of the various structural parts. However, it does not solve the problem of adjusting the particle size distribution and content ratio of the screened brown fused alumina product. Summary of the Invention

[0004] To overcome the shortcomings of existing particle size screening technologies, this invention proposes a simple, easily modifiable, and convenient brown fused alumina particle size screening device and method that can roughly adjust the particle size distribution and content ratio of the desired brown fused alumina product, save process and screening costs, improve the flexibility of brown fused alumina screening, and ensure product quality.

[0005] The specific technical solution is as follows:

[0006] A brown fused alumina particle size screening device is provided, including a feeding device and at least one particle size screening mechanism. The feeding device is located above the particle size screening mechanism. The feeding device directly conveys material from a crusher to the particle size screening mechanism via an inclined platform, or it uses a conveying pipe in conjunction with an auger structure to convey the material. The particle size screening mechanism has a shell structure. Inside the shell structure, a first screen structure, a second screen structure, and a third screen structure are arranged sequentially from top to bottom, with the mesh size of the first screen structure, the second screen structure, and the third screen structure increasing sequentially. A discharge port is opened on the side of the shell structure, and a [missing information - likely a device or component] is installed on the discharge port. The device is equipped with a layered discharge mechanism, which includes a first discharge channel, a second discharge channel, and a third discharge channel. The side edges of the first, second, and third screen structures are aligned with the first, second, and third discharge channels, respectively. A half-section screen structure is also provided above the first screen structure. The half-section screen structure is mounted on the shell structure, and its side edge is aligned with the top of the first discharge channel. The feeding device is aligned with the half-section screen structure, and the half-section screen structure has a larger mesh count than the first screen structure. A vibration mechanism is also provided on the shell structure.

[0007] The area of ​​the half-section screen structure is 10% to 90% of the area of ​​the first screen structure, and at least 10% of the discharge port of the feeding device is aligned with the half-section screen structure.

[0008] Preferably, the first screen structure, the second screen structure, the third screen structure, and the half-section screen structure are inclined, and the horizontal height of each is lower as it gets closer to the layered discharge mechanism.

[0009] Preferably, the vibration mechanism includes a motor vibration base and a polarization motor, wherein the polarization motor is mounted on the motor vibration base, and the motor vibration base is fixedly disposed on the outer wall of the housing structure.

[0010] Preferably, the bottom of the shell structure is conical, and a powder discharge channel is provided at the bottom of the conical shell. The third screen structure is used to filter and remove dust and unqualified particles.

[0011] Preferably, the powder discharge channel is connected to a collection device or dust removal equipment.

[0012] Preferably, the system includes three particle size screening mechanisms: a first-order particle size screening mechanism, a second-order particle size screening mechanism, and a third-order particle size screening mechanism. It also includes a support frame structure, the top of which is connected to the first-order, second-order, and third-order particle size screening mechanisms via elastic components. Furthermore, the layered discharge mechanism includes a first-order layered discharge mechanism, a second-order layered discharge mechanism, and a third-order layered discharge mechanism, which are respectively located at the discharge ports of the first-order, second-order, and third-order particle size screening mechanisms.

[0013] Preferably, the vertical heights of the first-order particle size screening mechanism, the second-order particle size screening mechanism, and the third-order particle size screening mechanism decrease sequentially through the support frame structure, and the height difference is at least the vertical height of the shell structure.

[0014] The first discharge channel of the first-stage particle size screening mechanism is connected to the return crusher for crushing, the second discharge channel is connected to the first-stage particle size collection device, and the third discharge channel is transported to the second-stage particle size screening mechanism through the conveying pipeline.

[0015] The first and second discharge channels of the second-order particle size screening mechanism are connected to a second-order particle size collection device, and the corresponding third discharge channel is used to transport the material to the third-order particle size screening mechanism.

[0016] The first and second discharge channels of the three-stage particle size screening mechanism are connected to a three-stage particle size collection device, and the third discharge channel is connected to a tail material collection device.

[0017] A method for screening brown fused alumina particle size is also provided. The method uses the half-section sieve structure to pre-screen a portion of the brown fused alumina entering the screening process. The brown fused alumina with a larger proportion of the required particle size range is left to enter the next screening process, while the brown fused alumina with a smaller proportion of the required particle size range is removed from the pre-screened brown fused alumina.

[0018] The beneficial effects of this invention are as follows: When it is necessary to control the particle size distribution and content ratio of brown fused alumina products, a half-section screen structure is used. Through the half-section screen structure, the portion of brown fused alumina with a lower content can be removed in advance before entering the screening part. Then, it enters the particle size screening mechanism for vibration filtration, so as to obtain brown fused alumina products with different particle size distributions and content ratios. Then, by adjusting the installation of half-section screen structures 205 with different areas, covering different areas above the first screen structure, the particle size distribution and content ratio of brown fused alumina products can be flexibly controlled, which improves the flexibility of brown fused alumina screening and further saves process and screening costs.

[0019] Equipped with a first-stage, second-stage, and third-stage particle size screening mechanism, along with a first-stage, second-stage, and third-stage layered discharge mechanism, this system can screen brown fused alumina products of different particle size ranges continuously, saving on processes and screening costs. It also includes a powder discharge channel connected to a collection device or dust removal equipment. During the vibration screening of brown fused alumina particles in each particle size screening mechanism, dust and local fragments are continuously shaken off. These dust and local fragments are then screened out through the third screen structure for centralized processing and reuse, improving utilization and ensuring the quality of subsequent brown fused alumina products. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the first combination of the present invention.

[0021] Figure 2 This is a schematic diagram of the second combination of the present invention.

[0022] Figure 3 This is a schematic diagram of the structure of the particle size screening mechanism and the layered discharge mechanism in this invention.

[0023] Figure 4 This is a schematic diagram of the structure of the layered discharge mechanism in this invention.

[0024] Explanation of reference numerals in the attached drawings: 1. Feeding equipment; 2. Particle size screening mechanism; 3. Layered discharge mechanism; 4. Vibration mechanism; 5. Crushed powder discharge channel; 6. Support frame structure; 7. First-stage particle size collection device; 8. Second-stage particle size collection device; 9. Third-stage particle size collection device; 10. Tail material collection device.

[0025] First-order particle size screening mechanism 21; second-order particle size screening mechanism 22; third-order particle size screening mechanism 23;

[0026] Shell structure 201; first screen structure 202; second screen structure 203; third screen structure 204; half-section screen structure 205;

[0027] First-stage layered discharge mechanism 31; second-stage layered discharge mechanism 32; third-stage layered discharge mechanism 33;

[0028] First discharge channel 301; Second discharge channel 302; Third discharge channel 303;

[0029] Motor vibration base 41; polarization motor 42. Detailed Implementation

[0030] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0031] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified; furthermore, unless otherwise explicitly specified and limited, the terms "set," "installed," "connected," and "linked" should be interpreted broadly. Example

[0032] like Figure 1 , Figure 2 , Figure 3 and Figure 4As shown: A brown fused alumina particle size screening device is provided, comprising a feeding device 1 and three particle size screening mechanisms 2, namely a first-stage particle size screening mechanism 21, a second-stage particle size screening mechanism 22, and a third-stage particle size screening mechanism 23. A support frame structure 6 is also provided, the top of which is connected and installed on the first-stage particle size screening mechanism 21, the second-stage particle size screening mechanism 22, and the third-stage particle size screening mechanism 23 through elastic components. The support frame structure 6 is used to support the first-stage particle size screening mechanism 21, the second-stage particle size screening mechanism 22, and the third-stage particle size screening mechanism 23 at different heights. The first-stage particle size screening mechanism 21, the second-stage particle size screening mechanism 22, and the third-stage particle size screening mechanism 23 respectively screen brown fused alumina products of different particle size ranges, and the screening is carried out continuously, saving process and screening costs.

[0033] The feeding device 1 is located above one of the particle size screening mechanisms 2. Alternatively, only one particle size screening mechanism 2 may be provided, or one or more particle size screening mechanisms 2 may be provided with one particle size screening mechanism 2. All particle size screening mechanisms 2 have almost identical structures, that is, the first-order particle size screening mechanism 21, the second-order particle size screening mechanism 21, and the third-order particle size screening mechanism 21 have identical structures, as follows:

[0034] The aforementioned particle size screening mechanism 2 is provided with a shell structure 201. Within the shell structure 201, a first screen structure 202, a second screen structure 203, and a third screen structure 204 are arranged sequentially from top to bottom, with the mesh size of the first screen structure 202, the second screen structure 203, and the third screen structure 204 increasing sequentially. A discharge port is provided on the side of the shell structure 201, and a layered discharge mechanism 3 is installed on this discharge port. Specifically, the layered discharge mechanism 3 includes a first-stage layered discharge mechanism 31, a second-stage layered discharge mechanism 32, and a third-stage layered discharge mechanism 33. The first-stage layered discharge mechanism 31, the second-stage layered discharge mechanism 32, and the third-stage layered discharge mechanism 33 are respectively located at the discharge ports of the first-stage particle size screening mechanism 21, the second-stage particle size screening mechanism 22, and the third-stage particle size screening mechanism 23. Furthermore, each layered discharge mechanism 3 has a similar structure, as follows:

[0035] like Figure 3 and Figure 4As shown, the aforementioned layered discharge mechanism 3 is provided with a first discharge channel 301, a second discharge channel 302, and a third discharge channel 303. The side edges of the first screen structure 202, the second screen structure 203, and the third screen structure 204 are respectively aligned with the first discharge channel 301, the second discharge channel 302, and the third discharge channel 303. The outlet orientation of the first discharge channel 301, the second discharge channel 302, and the third discharge channel 303 is adjusted according to the usage environment, i.e., an adaptive change is made during the manufacturing process. The first screen structure 202, the second screen structure 203, the third screen structure 204, and the half-section screen structure 205 are inclined, and the horizontal height of each is lower the closer it is to the layered discharge mechanism 3, which facilitates the sliding of the screen structure into the layered discharge mechanism 3 during vibration.

[0036] A half-section screen structure 205 is also provided above the first screen structure 202. The half-section screen structure 205 is installed on the shell structure 201. The side edge of the half-section screen structure 205 is aligned with the top of the first discharge channel 301. The feeding device 1 is aligned with the half-section screen structure 205. The mesh number of the half-section screen structure 205 is more than that of the first screen structure 202. The half-section screen structure 205 is not required for every particle size screening mechanism 2. It is only used when it is necessary to control the particle size distribution and content ratio of brown fused alumina products. The half-section screen structure 205 can remove the brown fused alumina with a lower content in advance before entering the screening. Then, it enters the particle size screening mechanism 2 for vibration filtration, so as to obtain brown fused alumina products with different particle size distribution and content ratio.

[0037] The area of ​​the half-section screen structure 205 is 10% to 90% of the area of ​​the first screen structure 202. At least 10% of the discharge port of the feeding device 1 is directly aligned with the half-section screen structure 205. By adjusting the installation of half-section screen structures 205 with different areas, the area covered above the first screen structure 202 will be different, so that the particle size distribution and content ratio of brown fused alumina products can be flexibly controlled, which improves the flexibility of brown fused alumina screening and further saves process and screening costs.

[0038] Furthermore, a bayonet structure is provided on the inner wall of the shell structure 201. The half-section screen structure 205 consists of a screen and a mounting frame. One side of the mounting frame can be detachably installed in the bayonet structure, which facilitates the replacement of half-section screen structures 205 with different areas. The first screen structure 202, the second screen structure 203, and the third screen structure 204 have similar structures, except that the mesh count of the screen is different. Alternatively, they can be disassembled and removed when the half-section screen structure 205 is not needed. Similarly, a support bar can be detachably installed on the shell structure 201. The support bar is located at the bottom of the other side of the mounting frame of the half-section screen structure 205, which helps to improve the load-bearing capacity of the half-section screen structure 205.

[0039] The aforementioned feeding device 1 can be directly conveyed from the crusher to one of the particle size screening mechanisms 2 via an inclined platform, or a conveying pipe can be set up in conjunction with an auger structure to convey the feed, wherein the auger structure is rotatably installed in the conveying pipe.

[0040] A vibration mechanism 4 is also provided on the shell structure 201. The vibration mechanism 4 includes a motor vibration seat 41 and a polarization motor 42. The polarization motor 42 is mounted on the motor vibration seat 41, and the motor vibration seat 41 is fixedly set on the outer wall of the shell structure 201.

[0041] The bottom of the shell structure 201 is conical, and a powder discharge channel 5 is provided at the bottom of the conical shell. The third screen structure 204 is used to filter and remove dust and unqualified particles. Therefore, the powder discharge channel 5 is connected to a collection device or dust removal equipment. During the process of vibrating and screening the brown fused alumina particles by various particle size screening mechanisms 2, dust and local fragments on the brown fused alumina will be shaken off. These dust and local fragments are screened out by the third screen structure 204 each time and then centrally processed. They can be reused, which improves the utilization rate and ensures the quality of subsequent brown fused alumina products.

[0042] Furthermore, such as Figure 1 As shown, the first-order particle size screening mechanism 21, the second-order particle size screening mechanism 22 and the third-order particle size screening mechanism 23 are supported by the support frame structure 6 and their vertical heights decrease sequentially, and the height difference is at least the vertical height of the shell structure 201.

[0043] The first discharge channel 301 corresponding to the first-stage particle size screening mechanism 21 is connected to the return crusher for crushing, and then returned to the screening. The corresponding second discharge channel 302 is connected to the first-stage particle size collection device 7. The corresponding third discharge channel 303 is transported to the second-stage particle size screening mechanism 22 through the conveying pipeline, or it can be directly transported to the second-stage particle size screening mechanism 22.

[0044] The first discharge channel 301 and the second discharge channel 302 of the second-order particle size screening mechanism 22 are connected to the second-order particle size collection device 8, and the corresponding third discharge channel 303 is used to transport the material to the third-order particle size screening mechanism 23.

[0045] The first discharge channel 301 and the second discharge channel 302 of the three-stage particle size screening mechanism 23 are connected to the three-stage particle size collection device 9, and the third discharge channel 303 is connected to the tail material collection device 10. This is a method of screening brown fused alumina products from large to small range. Among them, the brown fused alumina products collected by the first-stage particle size collection device 7 have the largest particle size range, followed by the brown fused alumina products collected by the second-stage particle size collection device 8, and finally the brown fused alumina products collected by the third-stage particle size collection device 9. Within a reasonable range of protection, it can be extended in sequence by simply adding a particle size screening mechanism 2 and a layered discharge mechanism 3.

[0046] Furthermore, such as Figure 2 As shown, a first-order particle size screening mechanism 21, a second-order particle size screening mechanism 22, and a third-order particle size screening mechanism 23 are set up.

[0047] A method for screening brown fused alumina particle size is also provided. The method uses the above-mentioned half-section sieve structure 205 to pre-screen a portion of the brown fused alumina entering the screening process. The brown fused alumina with a larger proportion of the required particle size range is left to enter the next screening process, while the brown fused alumina with a smaller proportion of the required particle size range is removed from the pre-screened brown fused alumina.

[0048] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims.

Claims

1. A brown fused alumina particle size screening device, characterized in that: The device includes a feeding device (1) and at least one particle size screening mechanism (2). The feeding device (1) is located above the particle size screening mechanism (2). The feeding device (1) directly conveys the material from the crusher to the particle size screening mechanism (2) via an inclined platform, or it can be equipped with a conveying pipe and an auger structure to convey the material. The particle size screening mechanism (2) is provided with a shell structure (201). Inside the shell structure (201), a first screen structure (202), a second screen structure (203), and a third screen structure (204) are arranged sequentially from top to bottom. The mesh size of the first screen structure (202), the second screen structure (203), and the third screen structure (204) increases sequentially. A discharge port is provided on the side of the shell structure (201). A layered discharge mechanism (3) is installed on the discharge port. The layered discharge mechanism (3) is provided with a first The discharge channel (301), the second discharge channel (302), and the third discharge channel (303) are provided. The side edges of the first screen structure (202), the second screen structure (203), and the third screen structure (204) are respectively aligned with the first discharge channel (301), the second discharge channel (302), and the third discharge channel (303). A half-section screen structure (205) is also provided above the first screen structure (202). The half-section screen structure (205) is installed on the shell structure (201). The side edge of the half-section screen structure (205) is aligned with the top of the first discharge channel (301). The feeding device (1) is aligned with the half-section screen structure (205). The mesh number of the half-section screen structure (205) is greater than that of the first screen structure (202). A vibration mechanism (4) is also provided on the shell structure (201). The area of ​​the half-section screen structure (205) is 10% to 90% of the area of ​​the first screen structure (202), and at least 10% of the discharge port of the feeding device (1) is aligned with the half-section screen structure (205).

2. The brown fused alumina particle size screening device according to claim 1, characterized in that: The first screen structure (202), the second screen structure (203), the third screen structure (204) and the half-section screen structure (205) are inclined, and the horizontal height of each is lower as it gets closer to the layered discharge mechanism (3).

3. The brown fused alumina particle size screening device according to claim 1, characterized in that: The vibration mechanism (4) includes a motor vibration seat (41) and a polarization motor (42). The polarization motor (42) is mounted on the motor vibration seat (41), and the motor vibration seat (41) is fixedly installed on the outer wall of the shell structure (201).

4. The brown fused alumina particle size screening device according to any one of claims 1-3, characterized in that: The bottom of the shell structure (201) is conical, and a powder discharge channel (5) is provided at the bottom of the conical shell. The third screen structure (204) is used to filter and remove dust and unqualified particles.

5. The brown fused alumina particle size screening device according to claim 4, characterized in that: The powder discharge channel (5) is connected to a collection device or dust removal equipment.

6. The brown fused alumina particle size screening device according to any one of claims 1-3 or 5, characterized in that: It includes three particle size screening mechanisms (2), namely a first-order particle size screening mechanism (21), a second-order particle size screening mechanism (22), and a third-order particle size screening mechanism (23), and also provides a support frame structure (6). The top of the support frame structure (6) is connected and installed on the first-order particle size screening mechanism (21), the second-order particle size screening mechanism (22), and the third-order particle size screening mechanism (23) through elastic components. The layered discharge mechanism (3) includes a first-order layered discharge mechanism (31), a second-order layered discharge mechanism (32), and a third-order layered discharge mechanism (33). The material feeding mechanism (32) and the three-stage layered discharge mechanism (33) are respectively set at the discharge ports of the first-stage particle size screening mechanism (21), the second-stage particle size screening mechanism (22) and the third-stage particle size screening mechanism (23). The support frame structure (6) is used to support and install the first-stage particle size screening mechanism (21), the second-stage particle size screening mechanism (22) and the third-stage particle size screening mechanism (23) at different heights.

7. The brown fused alumina particle size screening device according to claim 6, characterized in that: The first-order particle size screening mechanism (21), the second-order particle size screening mechanism (22) and the third-order particle size screening mechanism (23) are supported by the support frame structure (6) and their vertical heights decrease sequentially, and the height difference is at least the vertical height of the shell structure (201); The first discharge channel (301) of the first-order particle size screening mechanism (21) is connected to the return crusher for crushing, the second discharge channel (302) is connected to the first-order particle size collection device (7), and the third discharge channel (303) is transported to the second-order particle size screening mechanism (22). The first discharge channel (301) and the second discharge channel (302) of the second-order particle size screening mechanism (22) are connected to the second-order particle size collection device (8), and the corresponding third discharge channel (303) is transported to the third-order particle size screening mechanism (23). The first discharge channel (301) and the second discharge channel (302) of the three-stage particle size screening mechanism (23) are connected to a three-stage particle size collection device (9), and the third discharge channel (303) is connected to a tail material collection device (10).

8. A method for screening brown fused alumina particle size, characterized in that: Using the half-section screen structure (205) as described in claim 1, a portion of the brown fused alumina entering the screening process is pre-screened. The brown fused alumina with a larger proportion of the required particle size range is left to enter the next screening process, and the brown fused alumina with a smaller proportion of the required particle size range in the pre-screened brown fused alumina is removed.

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