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Fumes, silica

CAS No.69012-64-2
Chemical Name:Fumes, silica
CBNumber:CB7899203
Molecular Formula:
Formula Weight:0
MOL File:Mol file

Fumes, silica Property

Density 0.45-0.67[at 20℃]
form Fine white powder with particle sizes generally below 1mm. This is not the same as the commercial products “fumes silica,” “silica gel,” “precipitated silica,” or “fused silica.” It is formed during the electric arc production of elemental silicon from quartz, which is reduced to silicon monoxide, escaping from the furnace and oxidized by air to silicon dioxide. This condenses to form spherical particles. For the production of ferrosilicon, iron metal is added to the charge; during charging there is also exposure to crystalline silica.
Water Solubility 135mg/L at 37℃
EPA Substance Registry System Fumes, silica (69012-64-2)

Hazard and Precautionary Statements (GHS)

Symbol(GHS)
Signal wordWarning
Hazard statements H373
Precautionary statements P260-P314-P501

Fumes, silica Chemical Properties,Usage,Production

Chemical Properties Amorphous silica, the noncrystalline form of SiO2, is a transparent to gray, odorless, amorphous powder
Uses None; produced only as a by-product.
Definition Produced by the volatilization and vaporization of furnace feed materials during the production of ferrosilicon and silicon metals. Consists primarily of silicon dioxide with carbon and trace elements.
Application Silica-fume forms most of the dust and other particulates in the off-gases produced during the electrothermal production of ferrosilicon (Fe-Si) or silicon (Si). The dust is collected in baghouses and bagged without further treatment. Due to its high surface area, microsilica reacts readily with hydrated calcium silicates forming strong bonds, and for that reason it is sometimes called reactive silica. Therefore the addition of microsilica to hydraulic cements improves their mechanical strength, reduces their permeability, and enhances their workability, cohesiveness, and flowing properties and hence is extensively used as an additive to cements and monolithic refractories.
Health Hazard Amorphous silica fume exposure is associated with recurrent fever, similar to metal fume fever, and nonprogressive pulmonary changes.More recently, the importance of silica fume particle size on toxicity has been noted.8 Specifically, particles of the ultrafine size range may be expected to have higher toxicity compared with particles of larger size.
Safety Profile An inhalation hazard. Much less toxic than crystalline forms. Does not cause silicosis. See also other silica entries
Potential Exposure Amorphous fumed silica is used as a mineral, natural or synthetic fiber. A potential danger to those involved in the production and handling of fumed silica for paint pigments or catalysts. Diatomaceous earth is used in clarifying liquids, in manufacture of fire brick and heat insulators; used as a filtering agent; as a filler in construction materials; pesticides, paints, and varnishes. A potential danger to those involved in mining of diatomaceous earth or fabrication of products there from.
Incompatibilities Silica, amorphous is a noncombustible solid. Generally unreactive chemically. Incompatible with fluorine, oxygen difluoride, chlorine trifluoride. Soluble in molten alkalis and reacts with most metallic oxides at high temperature.
Toxics Screening Level The initial threshold screening level (ITSL) for the amorphous silica compounds (Silica Fume) is 60 μg/m3 based on an 8-hour averaging time.
Waste Disposal Sanitary landfill.