li xinyuan analyzes the chemical properties of silica fume for you-pg电玩城

    in the production process of ferroalloy plants, industrial silicon and ferrosilicon will discharge a large amount of high-temperature exhaust gas with dust during the high-temperature melting process. the exhaust gas directly discharged into the atmosphere will cause serious environmental pollution, and the main content of dust in the exhaust gas is sio2 dust, which is a fine spherical particle formed by condensation of high-temperature vaporized sio2, which accounts for about 90% of the weight. the silicon powder is an important raw material, and it can be widely used in construction engineering, hydraulic engineering, refractory materials, etc., and the market prospect is extremely broad. therefore, the treatment of exhaust gas and the collection of silicon powder are good things that are both environmentally friendly and of high economic value.

    the silicon powder collected by the ferroalloy factory generally needs to be purified and encrypted to eventually become commercial silicon powder. the commercial silicon powder is also called silica fume, silicon micropowder and micro silicon powder in engineering. its main component is sio2, followed by a small amount of al2o3, cao, k2o, fe2o3, mgo and other substances.

    chemical properties of silica fume:

    1. silica fume: appearance is gray or off-white powder, and the refractoriness is >1600 °c. volume weight: 1600~1700kg/m3.

    2. fineness of silica fume: the fineness of silica fume is less than 1 μm, accounting for more than 80%, the average particle size is 0.1-0.3 μm, and the specific surface area is 20-28 m2/g. its fineness and specific surface area are about 80 to 100 times that of cement and 50 to 70 times that of fly ash.

    3, particle morphology and mineral phase structure: in the formation process of silica fume, due to the surface tension in the process of phase change, the formation of amorphous phase spherical particles, and the surface is relatively smooth, and some are multiple circles agglomerates in which the ball particles stick together. it is a volcanic ash substance with a large specific surface area and high activity. a material containing silica fume, a tiny spheroid can act as a lubricant.

    the average particle size of the produced silicon powder is 0.1 um, which is only a few percent of the average particle size of the cement. after being mixed with cement concrete, it can be well filled in the voids of the cement particles to make the slurry denser. the silicon powder also has a pozzolanic reaction. after the silicon powder contacts the mixing water, the silicon-rich gel is first formed and the water is absorbed. the gel accumulates between the cement particles which have not been hydrated, and gradually wraps the cement particles and hydrates the product ca ( oh) 2 reacts with the surface of the above silica gel to form a c-s-h gel having a higher gel strength than ca(oh) 2 crystals. the production of c-s-h gel is mostly in the pores of cement-hydrated c-s-h gel, which greatly increases the structural density of concrete. therefore, it has excellent pozzolanic effect and particulate effect, which can improve the bleeding and cohesiveness of fresh concrete.