Raw & Exfoliated Vermiculite

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Raw & Exfoliated Vermiculite

General Description

Vermiculite is the geological name given to a group of hydrated laminar minerals which are aluminium iron magnesium silicates resembling mica in appearance.

Appearance

Golden Brown Expanded Granules

Origins

India/South Africa (Palabora)

Typical Specifications

Moisture 9.89%
SiO2 39.52%
Fe2O3 14.32%
TiO2 2.63%
Al2O3 13.74%
CaO 6.47%
MgO 10.68%
Alkalis 2.75%

L.O.I. 11.05

Available Sizes for Exfoliated Vermiculite

0-3 mm1-3 mm2-4 mm4-8 mm150 microns100 microns45 microns

Applications

Raw Vermiculite is extensively used for ladle topping in foundry industries. Exfoliated vermiculite is used in the friction brake linings market, high temperature insulation, loft insulation, sound insulation, various construction products, animal feeds, horticulture and many other industrial applications. The cation exchange properties of vermiculite, and its layered structure and surface characteristics are utilized in products such as fire resistant coatings and gaskets.

The water content, typically around 10%, gives Vermiculite the unusual property of expanding (termed Exfoliation) when heated rapidly, due to the interlaminar generation of steam.
Vermiculite is a safe inert material, light in colour. When heated it expands up to 30 times its original volume converting dense flakes of or into lightweight, porous granules containing innumerable minute air layers.
Exfoliated vermiculite is light and clean to handle, has a high insulation value, acoustic insulating properties and will absorb and hold a range of liquids. The granules are non-combustible and are insoluble in water and organic solvents.

Physical Properties

Bulk density 64-160 kg/cu m
4-10 lb/cu ft

pH (in water) 6.5-7.5

Combustibility Non-combustible

Sintering temperature 1300-1350C

Fusion point 1450-1500C

Cation exchange capacity 50-150 me/100g

Water holding capacity (a) 220-350% by wt
30-60% by vol

Thermal Conductivity at Different Densities:

Grades

Indian Standard Grades, South African Premium Grades

AGRICULTURAL

CONSTRUCTION

HORTICULTURAL

INDUSTRIAL

Raw(Unexpanded) Vermiculite for style="font-size: 10pt; color: black; font-family: Verdana;"C.I. and style="font-size: 10pt; color: black; font-family: Verdana;"D.I. foundries

In ladle topping applications, un-expanded granular oreforms of vermiculite (4-8 mm) are added to molten metal pouring ladles. Most often the ore form is used which reacts with slag in the ladle to allow easy removal of the slag layer. In cases where it is desirable to maintain a metal temperature in a ladle, the expanded vermiculite layer forms an efficient insulating blanket, and maintains the temperature in ladle upto 1500-1600 oC.

One of the most overlooked slag and inclusions source, is the slag that is present in under-Cooled blast furnace pig irons. This includes charcoal-reduced pig iron, coke-reduced pig iron, and on occasion, submerged arc-furnace pig iron. Slag from the pig irons described here, contain substantial amounts of iron oxide, and are very fluid. As a result, they require the use of dry slag coagulant such as unexpanded vermiculite. For better results, it should be used as a mixture with Perlite. In order to get supreme results, it should be added after the slag layer formed by use of style="font-size: 10pt; color: black; font-family: Verdana;"Perlite style="font-size: 10pt; color: black; font-family: Verdana;"Ore us removed.

Applications for Exfoliated Vermiculite

Horticulture

Vermiculite is well established as a growing medium. It is most commonly used in compost formulations, usually in combination with peat. Vermiculite / peat 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 fertilizers while the vermiculite itself contributes potassium, magnesium and a number of minor elements.

The air / water ratios for vermiculite / peat composts are ideal for the stimulation of root growth and 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 fertilizer, pesticides and herbicides. It is also used in a ground form for encapsulating seeds.

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 greater volume yield and accommodates a high liquid uptake while retaining good handling characteristics.

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 good protection 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. Being soft and non-abrasive, it has also been used effectively for insulation and cushioning the base of plastic-lined swimming pools.

Friction Linings

Vermiculite is now used extensively in the friction lining industry as a safe alternative to asbestos, and plays an important role in this field.

Fire Protection

Vermiculite is recognized 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.

Vermiculite Plasters

Vermiculite plasters can be made with either gypsum or Portland cement. The advantage which all types of vermiculite plasters have over conventional types of plasters are:

Vermiculite also improves the resistance to chipping of plasters due to the ability of vermiculite particles to accommodate dimensional change. Vermiculite plasters, whether gypsum or cement based, can be applied by hand or by spraying machine. Being a non-abrasive aggregate, vermiculite is well suited to spray application and the sprayed plasters can have an attractive decorative appearance.

Lightweight Concretes

Vermiculite concretes are lightweight, have good insulating properties and are intrinsically fire resistant. Vermiculite concretes may be used for 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.

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.

Attic / Loft Insulation

Loose fill 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.

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 and ease of placement.

Applications for Processed Vermiculite

Vermiculite may be milled either before or after exfoliation according to the range of particle sizes required. Such milled or ground material may be used for the production of condensation control paints; high performance gaskets and seals and for upgrading the fire resistance of organic foams and other polymer systems.

Applications for Chemically Processed and Modified 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 fiber products. This treatment substantially increases the thermal stability of the fibers. A 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 specialized additives for various industries. Developments in this area of research have indicated that it may be feasible to manufacture complex silicate structures which, when polymerized, would form inorganic analogues of organic polymer systems with unique properties of flexibility and fire resistance.