Environmental Sustainability Practices Adopted by Green Silicon Carbide Manufacturers
Brown fused allumina (BFA) is a highly wear-resistant abrasive widely used in grinding wheels, cutting tools and sandblasting materials. Its manufacturing process is complex and delicate, involving high-temperature smelting and strict raw material control. This article will introduce the manufacturing process of brown fused allumina and the raw materials used in detail.
The core of the brown fused allumina manufacturing process lies in high-temperature smelting. The manufacturing process mainly relies on the high affinity of aluminum for oxygen. During the smelting process of high-alumina bauxite, the impurities in the bauxite can be effectively reduced by controlling the type and amount of reducing agents. The process utilizes the oxides in the bauxite to react with carbon to form bauxite (Al2O3), while impurities such as iron, silicon and titanium are reduced to alloys and separated from the corundum. The specific chemical reactions are as follows:
3Fe2O3+C→2Fe3O4+CO↑
Fe3O4+C→3FeO+CO↑
FeO+C→Fe+CO↑
SiO2+Fe+2C→FeSi+2CO↑
TiO2+3C→TiC+2CO↑
TiO2+2C+3Fe→Fe3Ti+2CO↑
These reactions are carried out in an electric arc furnace, and the furnace temperature usually needs to reach 1800-1900℃ to ensure effective reduction and separation of oxides.
High Alumina
High alumina is the main raw material for manufacturing brown fused allumina. Its Al2O3 content is required to be greater than 76%, Fe2O3 content should be less than 7.0%, TiO2 content should be less than 5.5%, and the total amount of CaO+MgO should be less than 1.2%. When selecting high alumina, the particle size should also be controlled at 10-25mm to ensure uniform reaction.
Carbon Materials
Carbon materials are used to reduce impurities in high-alumina bauxite. Commonly used materials include petroleum coke, coke and anthracite. The higher the fixed carbon content of carbon materials, the better, because volatile matter and ash content will affect the quality of brown fused allumina. During the smelting process, these carbon materials react with the oxides in high-alumina bauxite to form ferrosilicon alloys and separate from the corundum melt.
Iron Filings
Iron filings act as diluents in the manufacture of brown fused allumina, especially when the iron oxide content in high-alumina bauxite in my country is low. The amount of iron filings added depends on the content of SiO2 and iron oxide in high-alumina bauxite. Cast iron filings are a commonly used type of iron filings. Their particle size needs to be small and easy to transport, and the aluminum content must be strictly controlled.
The manufacturing process of brown fused allumina is divided into four stages: furnace opening, smelting, control and refining. The smelting stage accounts for more than 80% of the entire process, and its main purpose is to melt the charge and reduce impurities. The refining stage is used to further remove impurities, ensure good precipitation and aggregation of ferrosilicon alloy, and exhaust the gas in the furnace.
Different process methods, such as pouring method, melting block method and expulsion method, are suitable for different production needs. These methods can be selected and adjusted according to the furnace type and production scale in actual operation.
Through a detailed understanding of the manufacturing process and raw materials of brown fused allumina, the production process can be better controlled and the quality of brown fused allumina can be improved. Mastering the basic knowledge of these processes and raw materials is of great significance to optimize the production process and improve product performance.
