Optical silicon carbide powder sorting device and method

Abstract

The invention discloses an optical silicon carbide powder sorting device and method. The device comprises a storage bin, a valve, a first vibrating screen, a first belt conveyor, a second vibrating screen, a second belt conveyor, a third vibrating screen, a third belt conveyor and a fourth belt conveyor. The method comprises the steps that crushed silicon carbide materials are subjected to three-stage series screening through the device, and multi-stage particle size accurate sorting is achieved by controlling the hole diameter of each stage of vibrating screen. The key improvement lies in that all components in contact with materials are made of electronic-grade special plastics, so that impurities are prevented from being introduced; and the whole separation process is carried out under a negative pressure system, so that dust is effectively recovered. Automatic, high-efficiency and high-purity separation of the silicon carbide powder is achieved, the working environment is remarkably improved, and the device is suitable for large-scale production of the semiconductor-grade silicon carbide powder.

Description

Technical Field

[0001] This invention relates to the field of silicon carbide crystal synthesis technology, and more specifically, to a sorting device and method for silicon carbide powder used in the semiconductor industry. Background Technology

[0002] Silicon carbide (SiC), as a core representative of third-generation semiconductor materials, possesses excellent physical and chemical properties such as a wide bandgap, high breakdown electric field, high thermal conductivity, and high electron saturation drift velocity, demonstrating enormous application potential in high-temperature, high-frequency, high-power, and radiation-resistant electronic devices. In recent years, with the rapid development of strategic emerging industries such as 5G communications, new energy vehicles, photovoltaic power generation, and rail transportation, the demand for high-performance silicon carbide semiconductor materials has become increasingly urgent.

[0003] High-purity silicon carbide powder is the basic raw material for preparing silicon carbide ingots (crystal growth), and its purity and particle size distribution directly affect the quality and performance of the final single crystal. Currently, the self-propagating high-temperature synthesis (SHS) method is commonly used in industry to prepare high-purity silicon carbide powder. This method uses silicon powder and carbon black as raw materials, reacting them at a high temperature of 1200–2000℃ to synthesize blocky silicon carbide products. The synthesized product has high strength and must undergo a series of post-processing steps such as crushing, sieving, and purification to obtain powder raw materials that meet the requirements for crystal growth.

[0004] In the existing production process, the screening (or sorting) process is particularly critical. Its purpose is to classify the crushed powder according to different particle size ranges to meet the specific requirements of downstream applications for raw material particle size. However, the screening methods commonly used in the industry, especially for the processing of small and medium-sized enterprises or specific grades of powder, still rely heavily on manual screening or semi-mechanized single-stage screening. This traditional method has the following significant disadvantages: (1) Manual operation or simple single-stage screening cannot achieve continuous and automated multi-stage sorting, the processing speed is slow, the capacity is limited, and it is difficult to meet the needs of large-scale production. (2) Manual screening is heavy physical labor. Moreover, silicon carbide dust is easily generated during the screening process. These micron-sized dust particles float in the air, which not only seriously pollute the working environment, but also pose a long-term threat to the respiratory health of operators. (3) If the screening equipment (such as screens, conveying parts) is made of inappropriate materials, metal or other impurity particles may fall off during long-term friction and collision, mix into the silicon carbide powder, cause secondary pollution, and affect the purity of the final product. (4) The instability of manual operation and the limitations of single-stage screening may lead to differences in particle size distribution between different batches of powder, affecting the stability and repeatability of the crystal growth process.

[0005] Therefore, developing a silicon carbide powder sorting device and method that can achieve automation, high efficiency, low pollution and is suitable for large-scale production has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] To address the aforementioned shortcomings of existing technologies, the present invention aims to provide an optical silicon carbide powder sorting device and method. This device and method are designed to achieve automated, multi-stage precision sorting of silicon carbide powder, significantly improving sorting efficiency, reducing manual labor intensity and health risks, and avoiding the introduction of new impurities during the sorting process, thereby supporting the promotion of high-quality silicon carbide semiconductor materials.

[0007] To achieve the above objectives, the specific solution adopted by the present invention is as follows: On one hand, the present invention provides a silicon carbide powder sorting device for optical applications, comprising: a storage bin, a valve, a first vibrating screen, a first belt conveyor, a second vibrating screen, a second belt conveyor, a third vibrating screen, a third belt conveyor, and a fourth belt conveyor; The discharge port of the storage silo is connected to the inlet of the first vibrating screen via a valve; The aperture of the first vibrating screen is 1mm-2mm. The fine material outlet of the first vibrating screen is connected to the feed inlet of the second vibrating screen, and the coarse material outlet of the first vibrating screen is connected to the first dedicated silo through the first belt conveyor. The aperture of the second vibrating screen is 0.5mm-1mm. The fine material outlet of the second vibrating screen is connected to the feed inlet of the third vibrating screen, and the coarse material outlet of the second vibrating screen is connected to the second special silo through the second belt conveyor. The aperture of the third vibrating screen is 0.2mm-0.5mm. The fine material outlet of the third vibrating screen is connected to the third special material bin via the fourth belt conveyor, and the coarse material outlet of the third vibrating screen is connected to the fourth special material bin via the third belt conveyor. The sorting device is placed in a negative pressure system, which is connected to a negative pressure pipeline for recovering the dust generated during the sorting process.

[0008] Furthermore, the first, second, and third vibrating screens are made of electronic-grade chemical-grade plastics; and / or; The first belt conveyor, the second belt conveyor, the third belt conveyor and the fourth belt conveyor are made of electronic-grade chemical-grade plastic.

[0009] Furthermore, the electronic-grade chemical-specific plastic is any one of polyethylene, nylon, or polyvinyl chloride.

[0010] Furthermore, the screens of the first, second, and third vibrating screens have a single-layer or multi-layer structure.

[0011] Furthermore, a bag filter is installed at the end of the negative pressure pipe connected to the negative pressure system.

[0012] On the other hand, the present invention provides a method for sorting optical silicon carbide powder using the above-described optical silicon carbide powder sorting device, comprising the following steps: Step S1: Crush the silicon carbide blocks to a particle size of less than 4mm and transfer them to the storage silo; Step S2: Turn on the power to the first vibrating screen and the first belt conveyor, open the valve, and slowly lower the silicon carbide material from the storage bin to the first vibrating screen; Step S3: Screening is performed by the first vibrating screen. The aperture of the first vibrating screen is 1mm-2mm. Materials with a particle size of less than 1mm flow into the second vibrating screen, while materials with a particle size of more than 1mm are transferred to the first special silo via the first belt conveyor. Step S4: Turn on the power to the second vibrating screen and the second belt conveyor. The second vibrating screen is used for screening. The aperture of the second vibrating screen is 0.5mm-1mm. Materials with a particle size of less than 0.5mm flow into the third vibrating screen, and materials with a particle size of more than 0.5mm are transferred to the second special hopper via the second belt conveyor. Step S5: Turn on the power to the third vibrating screen, the third belt conveyor and the fourth belt conveyor. Screening is carried out by the third vibrating screen. The aperture of the third vibrating screen is 0.2mm-0.5mm. Materials with a particle size of less than 0.2mm are transferred to the third special hopper by the fourth belt conveyor, and materials with a particle size of more than 0.2mm are transferred to the fourth special hopper by the third belt conveyor. The sorting device is placed in a negative pressure system, which is connected to a negative pressure pipeline for recovering the dust generated during the sorting process.

[0013] Furthermore, in step S2, the negative pressure system is started first, and then the valve is opened to release the material.

[0014] Furthermore, the silicon carbide lumps are crushed to a particle size of 0.5mm-4mm.

[0015] Compared with the prior art, the silicon carbide powder sorting device and method provided by the present invention have the following significant advantages: (1) This invention completely replaces the inefficient manual screening by adopting a continuous and automated design of “storage silo → multi-stage vibrating screen → belt conveyor → special silo”. The material flows automatically and multi-stage screening is completed in one go, which greatly improves the sorting efficiency and processing capacity, and makes large-scale and continuous production possible.

[0016] (2) The entire device of the present invention is placed under a negative pressure system. The dust generated during screening and transmission is effectively captured and recovered by the negative pressure pipeline, which fundamentally solves the problem of dust diffusion, creates a clean production environment, and significantly reduces the harm to the health of operators.

[0017] (3) All components in this invention that come into contact with the material, including the vibrating screen and the belt conveyor, are made of electronic-grade special plastics (such as PE, PA6, PVC). These materials are inherently clean and not easily worn, avoiding metal ion contamination that may be caused by traditional metal equipment, ensuring that no secondary impurities are introduced into the silicon carbide powder during the sorting process, and meeting the stringent purity requirements of semiconductor-grade materials.

[0018] (4) This invention uses a three-stage vibrating screen connected in series, with precise control of the screen aperture at each stage, to accurately separate silicon carbide powder into four distinct particle size levels. The mechanized operation ensures the stability and repeatability of the sorting process, resulting in a highly consistent particle size distribution among different batches of powder, which is beneficial for the stable control of the downstream crystal growth process.

[0019] (5) Although the initial equipment investment may be higher than that of simple tools, automated operation saves a lot of labor costs, increases production capacity with high efficiency, brings higher added value to high-quality products, and dust recovery also reduces material loss. In the long run, the overall production cost is reduced and the economic benefits are significant. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the optical silicon carbide powder sorting device of the present invention.

[0021] The labels in the diagram are as follows: 1. Storage silo; 2. Valve; 3. First vibrating screen; 4. First belt conveyor; 5. Second vibrating screen; 6. Second belt conveyor; 7. Third vibrating screen; 8. Third belt conveyor; 9. Fourth belt conveyor. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. 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 protection scope of the present invention.

[0023] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0024] In a first aspect, the present invention provides a sorting device for silicon carbide powder for optical applications. The sorting device includes a storage bin 1, a valve 2, a first vibrating screen 3, a first belt conveyor 4, a second vibrating screen 5, a second belt conveyor 6, a third vibrating screen 7, a third belt conveyor 8, and a fourth belt conveyor 9.

[0025] Storage silo 1 is used to store crushed (to below 4mm) silicon carbide blocks. A valve 2 is located at its bottom to control the material feeding speed and on / off state. A first vibrating screen 3 is connected below valve 2.

[0026] The first vibrating screen 3 is equipped with a screen with a specific aperture, the aperture range of which is controlled between 1 mm and 2 mm. The fine material outlet of the first vibrating screen 3 (for finer materials that pass through the screen) is connected to the feed inlet of the second vibrating screen 5, while its coarse material outlet (for coarser materials that do not pass through the screen) is connected to the first dedicated silo for collection via the first belt conveyor 4.

[0027] The second vibrating screen 5 is equipped with a screen with a specific aperture, the aperture range of which is controlled between 0.5 mm and 1 mm. The fine material outlet of the second vibrating screen 5 is connected to the feed inlet of the third vibrating screen 7, and its coarse material outlet is connected to the second dedicated hopper via the second belt conveyor 6.

[0028] The third vibrating screen 7 is equipped with a screen with a specific aperture, the aperture range of which is controlled between 0.2 mm and 0.5 mm. The fine material outlet of the third vibrating screen 7 is connected to the third dedicated silo via the fourth belt conveyor 9, and its coarse material outlet is connected to the fourth dedicated silo via the third belt conveyor 8.

[0029] As a key improvement, the first vibrating screen 3, the second vibrating screen 5, and the third vibrating screen 7 are all made of electronic-grade chemical-grade plastic. Preferably, the plastic is one of polyethylene (PE), nylon (PA6), or polyvinyl chloride (PVC). These materials have the characteristics of high purity, low wear, and corrosion resistance, which can effectively prevent the introduction of impurities such as metals into the silicon carbide powder due to equipment wear during the screening process.

[0030] Similarly, the first belt conveyor 4, the second belt conveyor 6, the third belt conveyor 8 and the fourth belt conveyor 9 are also made of the aforementioned electronic-grade chemical-specific plastics (PE, PA6 or PVC) to ensure the cleanliness of the entire material conveying path.

[0031] As another key improvement, the entire device is enclosed in a chamber (not shown in the figure), which is connected to an external negative pressure fan (not shown in the figure) via pipes to form a negative pressure system. During operation, the fan runs continuously, maintaining a slight negative pressure inside the chamber. Any dust generated is carried into the pipes by the airflow and eventually collected by a bag filter (not shown in the figure) at the end.

[0032] Secondly, the present invention provides a method for sorting silicon carbide powder for semiconductors using the above-described sorting apparatus. The method includes the following steps: Step S1, Pretreatment: The blocky silicon carbide product obtained by the self-propagating high-temperature synthesis method is crushed to a particle size of less than 4 mm, and then transferred to the storage silo 1 for later use; Step S2, First-stage screening: Turn on the power to the first vibrating screen 3 and the first belt conveyor 4; start the negative pressure system; then open the valve 2 at the bottom of the storage silo 1 to allow the silicon carbide material to slowly fall onto the first vibrating screen 3 under controllable conditions; after screening by the first vibrating screen 3 (aperture 1mm-2mm), the material with a particle size less than 1mm (fine material) flows into the second vibrating screen 5, while the material with a particle size greater than 1mm (coarse material) is transported by the first belt conveyor 4 to the first special silo for collection; Step S3, Second-stage screening: Turn on the power to the second vibrating screen 5 and the second belt conveyor 6; the fine material from the first-stage screening is screened on the second vibrating screen 5 (aperture 0.5mm-1mm); the material with a particle size less than 0.5mm flows into the third vibrating screen 7, and the material with a particle size greater than 0.5mm is transported by the second belt conveyor 6 to the second special silo for collection. Step S4, Third-stage screening: Turn on the power to the third vibrating screen 7, the third belt conveyor 8, and the fourth belt conveyor 9; the fine material from the second-stage screening is finally screened on the third vibrating screen 7 (aperture 0.2mm-0.5mm); the material with a particle size less than 0.2mm (the finest grade) is conveyed to the third special silo for collection by the fourth belt conveyor 9, and the material with a particle size between 0.2mm and 0.5mm is conveyed to the fourth special silo for collection by the third belt conveyor 8.

[0033] Throughout the sorting process, the negative pressure system operates continuously, collecting and treating the dust generated within the unit through negative pressure pipelines. This fundamentally solves the problem of dust dispersion, creates a clean production environment, and significantly reduces the health hazards to operators.

[0034] Example 1 This embodiment discloses a method for sorting silicon carbide powder for semiconductors, mainly including the following steps: First, approximately 100 kg of crushed silicon carbide raw material (maximum particle size <4 mm) is fed into storage silo 1. Then, the negative pressure system, the first vibrating screen 3, and the first belt conveyor 4 are started sequentially. Valve 2 is slowly opened to allow the material to be evenly spread on the first vibrating screen 3. After screening, coarse material >1.5 mm is sent to the first dedicated silo by the first belt conveyor 4. The material passing through the screen falls into the second vibrating screen 5, at which point the second vibrating screen 5 and the second belt conveyor 6 are started. On the second vibrating screen 5, powder with a particle size between 0.7 mm and 1.5 mm is retained and sent to the second dedicated silo by the second belt conveyor 6. Finer material falls into the third vibrating screen 7, at which point the third vibrating screen 7, the third belt conveyor 8, and the fourth belt conveyor 9 are started. On the third vibrating screen 7, powder with a particle size between 0.3 mm and 0.7 mm is retained and sent to the fourth dedicated silo by the third belt conveyor 8. The finest powder, with a particle size <0.3mm, passes through a sieve and is conveyed to the third dedicated silo by the fourth belt conveyor 9. The entire process is continuous until all raw materials have been processed. Ultimately, silicon carbide powder was successfully separated into four different particle size grades. The entire process was dust-free, highly efficient, and produced pure products.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention in any way. All equivalent transformations or modifications made in accordance with the essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. An optical silicon carbide powder sorting device, characterized in that, include: Storage bin (1), valve (2), first vibrating screen (3), first belt conveyor (4), second vibrating screen (5), second belt conveyor (6), third vibrating screen (7), third belt conveyor (8) and fourth belt conveyor (9); The discharge port of the storage silo (1) is connected to the inlet of the first vibrating screen (3) through a valve (2); The aperture of the first vibrating screen (3) is 1mm-2mm. The fine material outlet of the first vibrating screen (3) is connected to the feed inlet of the second vibrating screen (5). The coarse material outlet of the first vibrating screen (3) is connected to the first special silo through the first belt conveyor (4). The aperture of the second vibrating screen (5) is 0.5mm-1mm. The fine material outlet of the second vibrating screen (5) is connected to the feed inlet of the third vibrating screen (7). The coarse material outlet of the second vibrating screen (5) is connected to the second special silo through the second belt conveyor (6). The aperture of the third vibrating screen (7) is 0.2mm-0.5mm. The fine material outlet of the third vibrating screen (7) is connected to the third special material bin via the fourth belt conveyor (9), and the coarse material outlet of the third vibrating screen (7) is connected to the fourth special material bin via the third belt conveyor (8). The sorting device is placed in a negative pressure system, which is connected to a negative pressure pipeline for recovering the dust generated during the sorting process.

2. The sorting device according to claim 1, characterized in that, The first vibrating screen (3), the second vibrating screen (5) and the third vibrating screen (7) are made of electronic-grade chemical-grade plastic; and / or; The first belt conveyor (4), the second belt conveyor (6), the third belt conveyor (8) and the fourth belt conveyor (9) are made of electronic-grade chemical-grade plastic.

3. The sorting device according to claim 2, characterized in that, The electronic-grade chemical-specific plastic is any one of polyethylene, nylon, or polyvinyl chloride.

4. The sorting device according to claim 1, characterized in that, The screens of the first vibrating screen (3), the second vibrating screen (5) and the third vibrating screen (7) are single-layer or multi-layer structures.

5. The sorting device according to claim 1, characterized in that, The negative pressure system is connected to a negative pressure pipeline with a bag filter at the end.

6. A method for sorting optical silicon carbide powder using the optical silicon carbide powder sorting device according to any one of claims 1-5, characterized in that, Includes the following steps: Step S1: Crush the silicon carbide blocks to a particle size of less than 4 mm and transfer them to the storage silo (1). Step S2: Turn on the power to the first vibrating screen (3) and the first belt conveyor (4), open the valve (2), and slowly lower the silicon carbide material from the storage bin (1) to the first vibrating screen (3). Step S3: Screening is performed by the first vibrating screen (3). The aperture of the first vibrating screen (3) is 1mm-2mm. Materials with a particle size of less than 1mm flow into the second vibrating screen (5), and materials with a particle size of more than 1mm are transferred to the first special silo via the first belt conveyor (4). Step S4: Turn on the power to the second vibrating screen (5) and the second belt conveyor (6), and screen through the second vibrating screen (5). The aperture of the second vibrating screen (5) is 0.5mm-1mm. Materials with a particle size of less than 0.5mm flow into the third vibrating screen (7), and materials with a particle size of more than 0.5mm are transferred to the second special silo through the second belt conveyor (6). Step S5: Turn on the power to the third vibrating screen (7), the third belt conveyor (8) and the fourth belt conveyor (9). Screening is carried out through the third vibrating screen (7). The aperture of the third vibrating screen (7) is 0.2mm-0.5mm. Materials with a particle size of less than 0.2mm are transferred to the third special silo through the fourth belt conveyor (9), and materials with a particle size of more than 0.2mm are transferred to the fourth special silo through the third belt conveyor (8). The sorting device is placed in a negative pressure system, which is connected to a negative pressure pipeline for recovering the dust generated during the sorting process.

7. The sorting method according to claim 6, characterized in that, In step S2, the negative pressure system is started first, and then the valve (2) is opened to release the material.

8. The sorting method according to claim 6, characterized in that, The silicon carbide blocks are crushed to a particle size of 0.5mm-4mm.

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