A quick glance at this versatile mineral and its application.
SO, WHAT IS PERLITE AND IN WHICH INDUSTRY DO YOU USE IT?
Perlite is a non-toxic, naturally occurring siliceous volcanic rock. Perlite is formed by the rapid cooling of viscous magma or lava. The distinguishing feature which sets perlite apart from other volcanic glasses is that when heated to a suitable point in its softening range, it expands from four (4) to approximately twenty (20) times its original volume!
This expansion process is due to the presence of two to six percent combined water in the crude perlite rock. When quickly heated to above 870°C, the crude rock pops (almost like popcorn) as the combined water vaporizes and creates countless tiny bubbles in the heat softened glassy particles. It is these tiny glass-sealed bubbles which account for the amazing light weight and other exceptional physical properties of expanded perlite. Unexpanded (“raw”) perlite has a bulk density around 1100 kg/m3 (1.1 g/cm3), while typical expanded perlite has a bulk density of about 30–150 kg/m3 (0.03-0.150 g/cm3).
The expansion process also creates the perlite’s white colour – which is one it’s most distinguished characteristics. While the crude perlite rock may range from transparent to light grey to glossy black, the colour of expanded perlite ranges from snowy- to greyish white. Expanded perlite can be manufactured to weigh from 32 kg/m3 to 240 kg/m3, making it adaptable for numerous uses!
Because of the perlite mineral’s low density and relatively low price, many commercial applications have developed over the past few years. In the construction and manufacturing fields, it is used in lightweight plasters, concrete, insulation and ceiling tiles. In horticulture, perlite can be used as a soil amendment or alone as a medium for hydroponics or for starting cuttings. When used as an amendment it has high permeability / low water retention and helps prevent soil compaction.
Perlite is an excellent filtration aid and is used extensively as an alternative to diatomaceous earth (a soft, crumbly, porous sedimentary deposit formed from the fossil remains of diatoms). The popularity of perlite usage as a filter medium is growing considerably worldwide. Perlite filter medium are used in filtering beer and wine before it is bottled. Small quantities of perlite are also used in foundries, cryogenic insulation, and in ceramics as a clay additive. It is also used by the explosives industry.
Perlite is a non-renewable resource. The Perlite that is used by Sun Silicates is imported from Turkey, because they have large quantities of high quality perlite deposits. South Africa also has a perlite deposit, but this is only used for insulation in the construction industry and not for filtration industry.