Asbestos Compounds
Asbestos is a naturally occurring material used extensively in construction. It became a favorite of manufacturers and builders at the near end of the late 19th century owing to its strong heat, electrical and chemical resistance. It has moderate sound absorption and tensile strength properties. It occurs in nature as long, thin fibrous crystals in a set of six fibrous silicate minerals.
Kinds of Asbestos
The six silicate minerals defined as asbestos include Actinolite, Amosite, Anthophyllite, Chrysotile, Crocidolite and Tremolite.
Actinolite
Commonly found in metamorphic rocks, Actinolite asbestos is usually gray, green, or white in color. It contains a great quantity of iron and its chemical formula is Ca2(Mg, Fe)5(Si8O22)(OH)2. It is not of much commercial or industrial use but it may occur as a contaminant in other asbestos products.
Amosite or Brown Asbestos
Instantly recognized by its straight, brittle, light gray to brown in color fibers, Amosite was once commonly used as an insulating material (as a fire retardant several products like ceiling tiles). The chemical formula for Amosite is given as Fe7Si8O22(OH)2.
Anthophyllite
Anthophyllite, (Mg, Fe)7Si8O22(OH)2, has chain- like crystals that are brittle and white in color. Like Actinolite, Anthophyllite is a common contaminant as well and not of much industrial relevance. It is formed by talc breakdown in Ultramafic rock (igneous and meta-igneous rocks with low silica content).
Chrysotile
Obtained from Serpentinite rock, a form of Metamorphic rocks, Chrysotile’s fibers are curly in contrast to needlelike fibers of others. It is the most extensively used asbestos in the United States accounting for about 95% of the buildings in America. Owing to its flexible disposition, Chrysotile can be spun and woven in to a fabric or made into flat sheets. It is an ideal material for cement roof sheets, floor tiles, rope seals used in high temperature boilers, and flat sheets for ceilings, walls and floors. It is also used in brake linings and pipe insulation. Its chemical formula is Mg3(Si2O5)(OH)4.
Crocidolite
Crocidolite or blue Asbestos is considered to the most lethal form of Asbestos. It has straight blue fibers and occurs in bundles of very long lengths. It is found in countries like Australia, Bolivia, Canada and South Africa. Its chemical formula is given as Na2Fe2+3Fe3+2Si8O22(OH)2.
Tremolite
It is commonly found in most of the metamorphic rocks. Its colors range from creamy white to dark green. Though used for variety of construction and insulation materials in the past, it has not been as popular as its other forms. The chemical formula for Tremolite is Ca2Mg5Si8O22(OH)2.
Dangers of Asbestos
High concentrations of Asbestos inhaled over a long period can lead to severe diseases. Mesithelioma, a rare and deadly form of cancer that attacks the lining of the lungs, heart, or abdomen, is a direct result of prolonged asbestos exposure. Other diseases include Asbestos warts, Pleural Plaque and diffusive pleural thickening.
Substitutes of Asbestos
Due to a worldwide commercial ban on the production and usage of Asbestos, many companies are switching to its substitutes. Fiber glass, Eternit, stonefibers and Polybenzimidazole or PBI fiber are the most common substitutes available.
In most developing countries, certain companies like, A G & M Limited undertake safe disposal and recycling of Asbestos and related products.