Vermiculite

Vermiculite is a term applied commercially to micaceous minerals (essentially hydrated silicates of Al, Mg and Fe), usually alteration products of biotite or phlogopite micas, formed by the removal of much alkalies and addition of water. Vermiculite differs from mica in its characteristic property, i.e., exfoliation. Crude vermiculite is mostly exfoliated before use. In order to convert raw vermiculite into a product suitable for industrial use, it must be exfoliated or expanded by heating, a process termed ‘exfoliation’.

Uses

• Horticultural : Vermiculite is known for its horticultural applications. It is a common component in potting soils. Unfoliated (unexpanded) vermiculite has only minor uses, such as for circulation in drilling muds and in the annealing of steel.

• Insulation : Vermiculite is chemically inert, fireproof, nonconductor of electricity and a good insulator against heat (both radiant and conducted), cold and sound. Unlike cork and other organic light weight insulating material, it does not rot and is not attacked by vermin and has a fair mechanical strength.

• Carrier : It is also used as a carrier in fertilizers, herbicides and insecticides.

• Binding Agent : Cementing mixtures of exfoliated vermiculite and binding agents such as gypsum and plaster, have been important products and are applied to structural steel members in commercial buildings.

• Fireproof Plaster/ Refractory Board : The mineral is used in various types of building boards. Fine-sized, untreated vermiculite concentrates are included in the preparation of fireproof plaster boards. The exfoliated product forms the basis of some light weight plasterboard, whilst ground, exfoliated vermiculite is used in various refractory board products. The principal uses of expanded vermiculite are based on its thermal insulating quality (due to presence of innumerable air cells), low-density, fireproof nature and granular form.

• Thermal Insulation : Larger vermiculite granules are used as a loose fill for thermal insulation for homes, industrial structures, cold storage, refrigeration and high temperature and low temperature industrial equipment. The high absorbency and chemical inertness of exfoliated vermiculite have made it suitable for a wide range of absorbent packing materials as well as for packaged units for the spill containment of oil and similar liquids.