Silica Sand (Filter Media) General

Silica Sand (Filter Media) General HSN: 2505

silica. (silicon dioxide). widely in nature as sand, quartz, flint, and diatomite.
SiO2. Occurs

Properties: Colorless crystals or white powder, odorless and tasteless, d 2.2-2.6, insoluble in wa- "Sil ter and acids except for hydrogen fluoride, soluble in molten alkali when finely divided and amorphous. Combines chemically with most metallic oxides; melts to a glass with the lowest known co-efficient of expansion (fused silica); thermal conductivity about half that of glass, mp 1710C, bp 2230C, high dielectric constant, high heat, and shock resistance. Noncombustible.
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Derivation: Can be made from a soluble silicate si (water glass) by acidification, washing, and ignition. Arc silica is made from sand, and vaporized in a 3000C electric arc.
Grade: By purity and mesh size, silica aerogel, hydrated, precipitated. Hazard: Toxic by inhalation, chronic exposure to dust may cause silicosis.

Use (powder): Manufacture of glass, water glass, ceramics, abrasives, water filtration, micro-spheres, a component of concrete, source of ferrosilicon and elemental silicon, filler in cosmetics, pharmaceuticals, paper, insecticides, hydrated and precipitated grades as rubber reinforcing agent, including silicone rubber, anticaking agent in foods, flattening agents in paints, thermal insulator. (Fused): Ablative material in rocket engines, spacecraft, etc.; fibers in reinforced plastics; special camera lenses.

(Amorphous): Silica gel.
See also quartz, silicic acid, and silica gel.