Vermiculite is the geological name given to a group of hydrated laminar minerals which are aluminium-iron-magnesium silicates, resembling mica in appearance. Rock and other impurities are removed from the crude ore which is then crushed and sorted into sizes. Vermiculite is a safe inert material and is light in colour. When heated it expands (exfoliates) up to 30 times its original volume. The exfoliation process converts the dense flakes of ore into lightweight porous granules containing innumerable minute air layers. Exfoliated (expanded) vermiculite is light and clean to handle, has a high insulation value, acoustic-insulating properties and will absorb and hold a wide range of liquids. These granules are non-combustible, and are insoluble in water and all organic solvents. Expanded vermiculite is easily poured, is light, clean, highly absorbent and provides baffle against impact shock when used for packaging. Exfoliated vermiculite is used in the friction brake linings market, high temperature insulation, loft insulation, various construction products, animal feeds, horticulture and many other industrial applications. Vermiculite with its layered structure and surface characteristics, is utilised in products such as intumescent coatings and gaskets, the treatment of toxic waste and air-freight packaging of hazardous goods.
Animal Feedstuffs
Vermiculite is free flowing, soft, sterile and absorbent. This means it has found a role as a support and carrying medium for a range of nutrients such as fat concentrates, vitamin preparations and molasses. The use of vermiculite gives a high volume yield and accommodates a high liquid uptake whilst retaining good handling characteristics, so simplifying the process of mixing with other materials.
Bitumen Coated Vermiculite Screeds
Vermiculite, coated with a bituminous binder, can be used as a dry, lightweight roof screed. This type of screed has the advantages of low thermal conductivity, low moisture content, low density and ease of placement.
Chemically Processed Vermiculite
Chemical treatments can cause the layered structure of vermiculite to expand or delaminate, producing very high aspect ratio particles. Such dispersions play an important role in the coating of both organic and inorganic fibre products. This treatment substantially increases the thermal stability of fibresA whole new family of vermiculite products can be generated by varying the chemical process. It is possible to produce flexible films, papers and coatings, and to make specialised additives for various industries. Developments in this area of research have indicated that it may be feasible to manufacture complex silicate structures which, when polymerised, would form inorganic analogues of organic polymer systems with unique properties of flexibility and fire resistance.
Fire Protection
Vermiculite is recognised as a material particularly suited for fire protection. Vermiculite-based products range from factory made boards and panels to premixed coatings suitable for application by mechanical spray or by hand plastering techniques on a range of structures. These coatings are widely used in the petrochemical industry and in the tunnel lining.
Friction Linings
Vermiculite is now used extensively in the friction lining industry (e.g. brake and clutch linings) as a safe alternative to asbestos, and plays an important role in this field.
Horticulture
Vermiculite is well established as a growing medium. It is most commonly used in compost formulations, usually in combination with peat or coir. Vermiculite/peat or coir compost formulations provide ideal conditions for plant growth. The presence of vermiculite particles in the compost aids aeration, improves moisture retention and promotes the steady release of added fertilisers, whilst the vermiculite itself contributes potassium, magnesium and a number of minor elements. The air/water ratios for vermiculite/peat or coir composts are ideal for the stimulation of root growth, and hence the production of healthy young plants. The vermiculite is sterile when processed. If stored correctly it will need no further treatment before incorporation into composts. Vermiculite can also be used as a carrier and extender for fertilisers, pesticides and herbicides. It is also used in a ground form for encapsulating seeds.
Insulation in Steelworks and Foundries
Good thermal insulation, low density and its natural refractory properties combine with ease of application to make vermiculite a highly suitable material for use in steelworks and foundries. It is used for hot topping molten steel to reduce heat loss from ingots and ladles and generally as a loose-fill insulator.
Lightweight Concretes
Vermiculite concretes are lightweight, have good insulating properties and are intrinsically fire resistant. Vermiculite concretes may be used for insitu roof and floor screeds and in the fabrication of pre-cast products. Vermiculite concretes can also be used for insulating around back boilers and as a fire back support material.
Loft Insulation
Loosefill vermiculite can be used between joists in lofts for home insulation. The free flowing properties of exfoliated vermiculite make installation very simple. The insulating properties of vermiculite significantly reduce the loss of heat in cold weather and keep the interior cool in hot weather. It also functions as a sound absorbent material.
Packing Materials
Exfoliated vermiculite is a useful packaging medium. Not only is it lightweight, clean and easily poured around irregular shaped objects, it also provides a good baffle against shocks caused by impact and improper handling. Being highly absorbent, it safely retains leaks from packed materials such as hazardous chemicals. As it is inorganic it does not present any potential fire hazards. Exfoliated vermiculite can also be used as a packing material for storing fruit, bulbs and tubers. Vermiculite degrades naturally, so is easily disposed of. Being soft and non-abrasive it has also been used effectively for insulation and cushioning the base of plastic-lined swimming pools.
