Vermiculite

Vermiculite is a natural mineral that expands with the application of heat. The expansion process is called exfoliation and it is routinely accomplished in purpose-designed commercial furnaces. Vermiculite is formed by weathering or hydrothermal alteration of biotite or phlogopite.its name is from latin vermiculare, to breed worms, for the manner in which it exfoliates when heated. It typically occurs as an alteration product at the contact between felsic and mafic or ultramafic rocks such as pyroxenites and dunites. It also occurs in carbonatites and metamorphosed magnesium rich limestone.
general vermiculie formulae:
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1. (na0.21,k0.39,mg0.19,ca0.13m,6h2o)
2. (mg5,fe+20.2,fe+30.8) [si5.5,al2.5,o20] (oh)4
the commercial uses of vermiculite:
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the majority of applications call for vermiculite in its exfoliated form. vermiculite is a very versatile mineral because of its thermal stability and inertness. it is clean to handle, odorless, mold-resistant and also sterile due to the high temperature to which it is subjected in production.
vermiculite is used in the following segments of industries:
agricultural
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• animal feed
• anti-caking material
• bulking agent
• fertilizer carrier
• pesticide carrier
• seed encapsulant
• soil conditioner
horticultural
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• blocking mixes
• hydroponics
• micro-propagation
• potting mixes
• root cuttings
• seed germination
• seedling wedge mix
• sowing composts
• twin scaling bulbs
construction
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• acoustic finishes
• air setting binder
• construction board
• passive fire protection
• floor & roof screeds
• insulating and light-weight concrete
• gypsum plasterboard
• loosefill loft insulation
• sound deadening compounds
industrial
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• absorbent packing for hazardous goods
• brake pads & brake shoes
• castables
• dispersions
• drilling muds
• filtration
• fireproof safes
• fixation of hazardous material
• furnaces
• insulation blocks & shapes
• insulation - high & low temperature
• molten metal insulation
• moulded products
• nuclear waste disposal
• paints
• perfume absorbent
• sealants
typical specification of raw vermiculite:
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sio2 : 28.03%
fe2o3 : 16.73%
al2o3 : 14.56%
cao : 2.62%
mgo : 14.73%
tio2 : 1.48%
na2o : 0.05%
loi : 11.8%
rate of exfoliation: 9 – 1- times
asbestos content: nil
sizes available: 0.5 mm/ 1-2 mm/ 2-4 mm/ 4-8 mm
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typical specification of exfoliated vermiculite:
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silica : 43.2%
alumina : 12.85%
iron : 15.30%
titanium oxide : 2.71%
calcium : 2.16%
magnesium : 10.80%
sodium : 1.08%
potassium : 5.95%
loi : 5.95%
asbestos content : nil
sizes available: 0.5 mm/ 1-2 mm/ 2-4 mm
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the future
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the traditional usage of vermiculite will continue well into the 21st century. Applications for processed and chemically modified vermiculites are also expected to arise in new and more diverse market areas; such forms of vermiculite thereby becoming valued products in the future years.