Everything about Perlite totally explained
» For the two-phased structure in steel see pearlite.
Perlite is an
amorphous volcanic glass that has a relatively high
water content, typically formed by the hydration of
obsidian. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently.
Properties and uses
When it reaches temperatures of 850–900 °C, perlite softens (since it's a glass). Water trapped in the structure of the material vapourises and escapes and this causes the expansion of the material to 7–16 times its original volume. The expanded material is a brilliant white, due to the reflectivity of the trapped bubbles.
Unexpanded ("raw") perlite
bulk density: around 1100 kg/m³ (1.1 g/cm³).
Typical expanded perlite bulk density: 30–150 kg/m³
Due to its low density and relatively low price, many commercial applications for perlite have developed. In the
construction and manufacturing fields, it's used in lightweight
plasters and
mortars,
insulation, ceiling tiles and filter aids. In
horticulture it makes composts more open to air, while still having good water-retention properties; it makes a good medium for
hydroponics. Perlite is also used in
foundries,
cryogenic insulations, as a lightweight aggregate in
mortar (firestop) and in
ceramics as a
clay additive.
Typical analysis of perlite
Production trends
In 2005, Greece was the top producer of perlite with at least one-third world share followed by China, USA, Japan and Turkey.
In
2001 the cost of perlite was about
US$36.31 per
metric ton. The yearend price for mined perlite in the US has increased since then:
» 2001.....$36.3 per
metric ton
2002.....$36.5 per metric ton
» 2003.....$38.2 per metric ton
2004.....$40.6 per metric ton
» 2005.....$42.5 per metric ton
Further Information
Get more info on 'Perlite'.
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