|Microsilica (Silica Fume)is a by product of producing silicon metal or ferrosilicon .. The smoke that results from furnace operation is collected and sold as silica fume, rather than being landfilled. Silica fume consists primarily of amorphous (non-crystalline) silicon dioxide (SiO2).
Its average granule diameter is 0.1-0.15um, which is smaller than 1% of cement. Its B.E.T Fineness is 15-27m2/g, which is a very reactive pozzolan.
Our company classify the products according to the content of SiO2 between 85% to 95%, its physical character and chemical component as following:
Microsilica, also known as silica fume, is a by product of the reduction of high-purity quartz with coal in electric furnaces in the production of silicon and ferrosilicon alloys. Microsilica is also collected as a by product in the production of other silicon alloys such as ferrochromium, ferromanganese, ferromagnesium, and calcium silicon. Before the mid-1970s, nearly all microsilica was discharged into the atmosphere. After environmental concerns necessitated the collection and landfilling of microsilica, it became economically justified to use microsilica in various applications.
Microsilica consists of very fine vitreous particles with a surface area ranging from 60,000 to 150,000 ft^2/lb or 13,000 to 30,000 m^2/kg when measured by nitrogen absorption techniques, with particles approximately 100 times smaller than the average cement particle. Because of its extreme fineness and high silica content, Microsilica is a highly effective pozzolanic material. Microsilica is used in concrete to improve its properties. It has been found that microsilica improves compressive strength, bond strength, and abrasion resistance; reduces permeability; and therefore helps in protecting reinforcing steel from corrosion.