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imagen asbestos

Asbestos

Overview

The word "Asbestos" comes from the Greek and means "Fireproof" and is a term used interchangeably to refer to a "family" composed of natural mineral fibers. The use of asbestos dates back to at least two thousand years. There is evidence that ancient cultures like the Greeks, Egyptians and Chinese used it since.

The mineralogical origin of the asbestos goes back to the time of the formation of our planet. It is stated that when rocks cooled, cracks formed therein through, which flowed hot mineral together with water and various gases and when crystallized, asbestos was formed.

Asbestos fibers are composed of microscopic fibers, granted by its physical, mechanical and thus versatility is characterized by its resistance to fire, friction, abrasion, chemicals and microorganisms; besides being thermal, acoustic and electric insulator.

Being asbestos natural fibers are found throughout the earth's crust, and the main mines are located in Brazil, Russia, Kazakhstan and China.

It has sought to match their features and performance with various substitutes manufactured products, however it must be used for more than 50 different inputs, whose response to specific conditions, such as exposure to high temperatures, is highly questionable, in addition that its harmlessness, has not been demonstrated.

Use of asbestos, history.

Ancient cultures.

The use of asbestos goes back about two thousand years ago. There are precedents of the use of asbestos in Greece, Egypt and China, being used as wicks for oil lamps and the Olympic torch “inextinguishable “flame. Later on, in Rome, it was known as" Amiantus” meaning immaculate , this name was given because when the fabrics were subjected to fire, surface stains disappear , being extremely clean fabrics.

There are some facts about the history, legends and mythology related to asbestos. The earliest mention of asbestos comes from the Greek text: “Over Rocks ", written by Theophrastus in 300 bC, who describes asbestos as “a substance that burns like wood, when mixed with oil, but that is not consumed."

It is known that asbestos was extracted in some mines of Crete, where it was transported to Greece, Rome and Egypt.

The ancient sages referred the origin of the extraordinary asbestos fibers, as “the mythical salamander’s fire resistant hair. Plinius “the elder” mentioned some uses of asbestos fabrics, such as a fire proof material. Plutarch described the wicks of the lamps of the Vestal made with asbestos, an “inextinguishable“ material. The Romans wove robes to use during the cremation of their corpses, in order to retain the ashes of the body pure and not mix with the ashes of the wood, for their ceremonial burials.

Since ancient times, asbestos properties captured the attention of magicians, alchemists, inventors, kings, emperors and warriors. Carlo Magno had a tablecloth woven with asbestos fibers that impressed his guests; he cleaned and bleached it, simply by entering the tablecloth into the fire. Marco Polo, during the second half of the thirteenth century, visited asbestos mines in China, describing the process of extracting ore from a rock, eliminating the old "theory of the salamander".

Despite the qualities and properties of asbestos, this fiber was not used much in at that time. However, applications have been many and varied, like the “eternal book” that would eventually be made with asbestos paper and written in golden letters.

In 1724 the young Benjamin Franklin, designed and manufacture a briefcase woven with asbestos fibers, in order to protect documents from fire; it still preserved in the collection of the Natural History Museum in London.

The physical properties of hardness, resistance and fireproofing of asbestos throughout history, have consistently stimulated the imagination, creativity and ingenuity of the man who has sought to give practical applications for his own benefit.

The Industrial Revolution, started industrial use of asbestos.

In 1834, the United Kingdom patented the use of asbestos with security measures. In 1853 British patent was registered to add asbestos to lubricants; in 1868 the first asbestos filters were patented, and in 1885, asbestos membrane filtration were manufactured, in a more sophisticated and higher quality.

In the late XIX century, it was necessary to isolate parts of the steam engine with asbestos, during the Industrial Revolution. Since then, the demand and the production of asbestos was on the rise and therefore, production, distribution and use, spread almost in all the industrial world.

An ally for the military industry.

During World War II, the U.S. Navy used asbestos to protect and strengthen decks of their ships and aircraft carriers, in some parts for the army vehicles (jeeps), on the ropes, parachute fabrics, structures of bazookas and torpedoes. It was also used in the electrolytic filtering processes, to obtain oxygen molecules from water within submarines. In recent dates, one of the most common uses was as thermal insulation and coating to resist friction in rockets and aerospace craft, launched into space during the XX century, now in disuse.

Postwar: Expand its applications and uses.

After the war, the use of asbestos expanded considerably. For example, it has been used in architecture, for the fire resistance in applications such as: ceilings, floors and coatings in construction.

It has also been used in mail bags , briefcases, safe boxes, sterilization equipment for surgical instruments, in military field hospitals , in containers for resistance and electrical insulation , filtration systems, manufacturing processes of chlorine, disinfectants and antiseptics, in the manufacture of automotive brake discs and pads, thermal and acoustic coatings, industrial bearings and the development of additives. Some of these uses are still in force.

Current applications.

The most current uses are fibro - cement products, such as pipes, sheets, tiles and others specialized textiles; friction products for auto brake pads, clutch dishes and as reinforcement for water proofing.

Asbestos types

The chemical composition and morphology of the asbestos fibers, are classified in two groups: serpentine and amphiboles.

Amphiboles are characterized by their fibers that are elongated and pointed, like needles.

In this group there are five subtypes:

imagen crocidolita

Crocidolite

It is also known as "blue asbestos". It has been proven that this fiber represents a major health risk, because the human body has no ability to remove quickly this kind of fibers once inhaled, due to its shape, size and chemical composition. The main deposits of this mineral are found in Australia and South Africa, which ceased operations years ago. Mexico stopped using this kind of asbestos from 1986.

imagen amosita

Amosite

Known as "brown asbestos" like the rest of the amphiboles, its fibers are long and pointed, but its structure is more fragile.

imagen antofilita

Anthophyllite

This type of asbestos is brittle, white, and contains several forms of iron.

imagen tremolita

Tremolite

It is white and sandy. The tremolite also can be found naturally in other minerals. For a long time, was used as the main ingredient in industrial and commercial talc.

imagen actinolita

Actinolite

The structure of this fiber is typically prismatic, flat and long.

Even though, amphiboles are regulated and permitted by current Mexican Legislation, the Mexican Industry stopped using amphiboles, in a voluntary Agreement from 1986 and formalized this practice in 1996, signing a voluntary agreement with the Ministry of Labor and Social Welfare (STPS).

In contrast to amphibole asbestos, the serpentine, as chrysotile, have curved, silky and helix shape fibers; also called as white asbestos.