Imerys Vermiculite 2013


Vermiculite has been used in various industries for over 80 years. It is used in the construction, agricultural, horticultural and industrial markets. Vermiculite is the mineralogical name given to hydrated laminar magnesium-aluminium-iron silicate which resembles mica in appearance.

Vermiculite is found in various parts of the world. Locations of the dominant commercial mines are in Australia, Brazil, China, Kenya, South Africa, USA and Zimbabwe.

Vermiculite mines are surface operations where ore is separated from other material, then screened or classified into several basic particle sizes.

When subjected to heat, vermiculite has the unusual property of exfoliating or expanding into worm-like pieces. The name 'vermiculite' is derived from the Latin 'vermiculare' meaning worm-like. This characteristic of exfoliation, the basis for many commercial uses of the mineral, is the result of the mechanical separation of the layers during the rapid conversion of contained water into steam. The increase in bulk volume of commercial grades is 8 to 12 times, but individual flakes may exfoliate as many as 30 times the original size. There is also a color change during expansion that is dependent upon the chemical composition of the vermiculite and the furnace temperature. The bulk density of crude vermiculite or vermiculite concentrate is in the range of 640-1120 kg/cubic metre. (40-70 lb/cubic foot) and exfoliated or expanded vermiculite is in the range of 64 - 160 kg/cubic metre (4 - 10 lb/cubic foot).