The Composition and Formation Process of Silica Fume
During the production process of ferroalloy plants, industrial silicon, and ferrosilicon will emit a large amount of high-temperature exhaust gas containing dust during the high-temperature smelting process. Direct discharge of this waste gas into the atmosphere will cause serious environmental pollution, and the main content of dust in the waste gas is SiO2 dust, which is a small spherical particle formed by the condensation of high-temperature gasified SiO2, accounting for almost 90% of the weight. This kind of silicon powder is an important raw material. It can be widely used in construction engineering, water conservancy projects, refractory materials, and other fields, and the market prospect is extremely broad. Therefore, waste gas treatment and collection of silicon powder are both beneficial to environmental protection and have high economic value.
The silicon powder collected through the ferroalloy factory generally needs to be purified and encrypted, and finally becomes commercial micro-silica powder, which is also called silica fume in engineering applications. Its main component is SiO2, followed by a small amount of Al2O3, CaO, K2O, Fe2O3, MgO, and other substances.
The country has corresponding national standard requirements for the quality of silica fume. In terms of chemical properties, the main requirements are SiO2 content ≥ 85%, loss on ignition ≤ 6%, and moisture content ≤ 3%. In terms of physical properties, the main requirement is a specific surface area ≥ 15000m2/kg. In terms of mortar performance, the volcanic ash activity index is required to be above 90%.
Silica Fume Uses
Microsilica fume is mainly used in cement or concrete admixtures to improve the performance of cement or concrete and prepare special concrete with ultra-high strength (above C70), wear resistance, erosion resistance, corrosion resistance, penetration resistance, frost resistance, and early strength. , used in projects such as dams, large reservoirs, hydropower, seaports and terminals, railway bridges, highways, airport runways, tunnels, and super high-rise buildings. At the same time, silica fume can also be used in the production of refractory materials and ceramic products to improve the strength and durability of products; it can be used as filler in paints, coatings, resins, rubber, and other polymer materials to improve the overall performance of materials. Purpose.
• Cement industry: After adding silica fume to cement, the performance is improved, and the quality and labeling are greatly improved.
• Rubber industry: After adding a certain amount of silicon powder to the rubber, its extension, contraction, tear-resistance, and aging resistance are greatly improved. This kind of rubber also has good dielectric properties and low water absorption capacity.
• Used as an anti-caking agent: instead of mica or diatomaceous earth as a raw material to prevent fertilizer particles from caking.
• Use as a pellet binder: Silica powder has a large specific surface area and strong adsorption. It has achieved remarkable results as a binder for pellets abroad.
• Water glass industry: It can replace quartz ore to produce water glass with a modulus of 4.
• Used as cementing in oil fields: Jilin Oilfield, Liaoning Oilfield, Karamay Oilfield, etc. all use silica powder in large quantities and have achieved good results.
• It is used in insulation materials, waterproof materials, paints, coatings, printing industries, etc.
Correct Storage of Silica Fume
Silica fumes should be stored in a dry, rain-proof, and sun-shaded environment.
• The product loses caking activity when exposed to water.
• It is forbidden to be exposed to the sun for a long time to avoid the weathering of the packaging bag and spilling of the product.
• This product is not a dangerous good, and transportation can be handled by the “Non-Dangerous Goods Regulations”.