Processing of silicon powder, silicon powder processing technology

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Processing of silicon powder, silicon powder processing technology. Introduction to the processing of silicon powder: safe, energy-efficient, high-performance, and high-quality silicon powder processing technology. Tsukasa Ichi. 1. Understanding and knowledge of silicon: Silicon is widely distributed in the Earth’s crust, accounting for about one-quarter of its total mass. Silicon has a wide range of uses; it is indispensable in daily life as well as in modern high-tech fields. As science and technology continue to develop, the practical value of silicon will become even more remarkable. For example, refining crude silicon into high-purity single-crystal silicon can yield a value several times that of gold, which illustrates the great versatility and economic viability of silicon. Silicon is produced by the reaction of silica SiO2 with carbon: SiO2 + 2C → Si + 2CO2↑. The silicon obtained in this way is crude silicon containing small amounts of impurities; it is also known as metallic silicon. Silicon accounts for about 98% of its composition, while elements such as Fe, Al, Ca, Zn, Cu, Ni, Sn, Pb, Mn, and Ti make up around 2%. Metallic silicon appears as gray-brown lumps with a metallic shine; it is hard and brittle. The symbol for silicon is Si, its atomic number is 14, and its atomic weight is 28.0355. The atomic radius of silicon is 1.17 μm. Its main oxidation states are +2 and +4. The electron configuration of a silicon atom is 3s2 3p2. In a silicon crystal, each silicon atom forms four covalent bonds with four other silicon atoms. The bond length in silicon crystals is 2.35×10^-10 μm, and the bond energy of Si–Si bonds is 42.5 kJ/mol. The density of silicon ranges from 2.32–2.34 g/cm3 to 2.32–2.4 g/cm3. Its melting point is 1410°C, and its boiling point is 2355°C℃ ； Silicon has electrical conductivity that lies between that of metals and insulators; it is a good semiconductor ； At room temperature, silicon has inert chemical properties ； Under heating conditions, silicon can react with many non-metals ； Silicon is insoluble in water ； For example, the thermal combustion of silicon powder produces silica while releasing a large amount of heat. Si + O2 → SiO2. II. Uses of the finished silicon powder: The finished silicon powder, which is produced through industrial processing of silicon blocks, is classified into coarse powder, fine powder, ultra-fine powder, and super-ultra-fine powder. It can be used as a key raw material in high-temperature refractory materials, iron, aluminum alloys, silica sols, silicone products, and more. At present, the development prospects for new silicone material products are promising, with a large market potential and substantial profit margins. Companies such as Dow Corning and GE in the United States, Wacker in Germany, Rhodia in France, Shin-Etsu in Japan, as well as silicone manufacturers in Thailand, have seen rapid growth in recent years, offering an increasing range of products. China’s silicone industry is also developing rapidly. Silicone companies produce methyl mixed crude monomers, using silicon powder as the main raw material. The main reaction is: Si + 2CH3Cl → (CH3)2SiCl2. The side reactions are: Si + 3CH3Cl → (CH3)SiCl3 + 2CH3; Si + CH3Cl + 2CH3 → (CH3)SiCl. Since China joined the WTO, the share of the domestic silicone industry in international trade has been increasing steadily, with the industry growing faster and becoming more competitive and high-quality. According to relevant reports, Zhejiang Yuantong Silicon Industry Co., Ltd. is building the largest silicon powder production plant in the country (50,000 tons per year) ； This year, the American companies Dow Corning and Wacker Chemie plan to establish a joint venture in Shanghai to build a production facility for microsilica products worth hundreds of millions of dollars. Therefore, the production technology of silicon powder has also become a focus of attention in related fields. This article provides a review of the technologies used to produce silicon powder in the silicone industry, for reference. III. Introduction to silicon powder production methods: There are various methods for producing finished silicon powder using silicon blocks as raw material. The methods that yield good results and are widely used include ball milling, roller milling, and impact milling. The main equipment used for these processes is ball mills, roller mills, and impact mills; these devices play a role in meeting the quality requirements in powder production. The first two are crushed by extrusion under gravity, while the last one is crushed by impact. Various mills can process and grind minerals that are not flammable or explosive and have a Mohs hardness of less than 7.0. The particle size of the finished product is controlled within the range of 30 mesh (0.613 mm) to 425 mesh (0.033 mm) through process adjustments. Table 1: Comparison of various production methods for silicon powder: Sequence Number, Item, Powdering Method – Ball milling, Roller milling, Disk milling, Jet milling. 1. Product quality: Specific surface area in m3/g – 0.26, 0.36, 0.42, 0.57; Particle size range in mm – 0~0.35, 0~0.35, 0.015, 0~0.4