Asbestos: what is asbestos, where does it originate, how has it been mined & used to manufacture products from ancient to modern times.
Where has asbestos been mined around the world, where are the principal asbestos deposits?
How is asbestos graded or classified - fiber lengths. Asbestos health issues ca 1959. Where do asbestos reserves remain? What are the principal product groups that used asbestos? This chapter forms the introduction to Rosato's Asbestos, its Industrial Applications (1959) .
This articles series about the manufacture & use of asbestos-containing products includes detailed information on the production methods, asbestos content, and the identity and use of asbestos-containing materials.
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In the more than half a centruy since Rosato published his enthsiastic little red book about asbestos this natural mineral has experienced a turbulent history that included valuable uses across thousands of products around the world and ultimately high costs of personal illness and asbestos cleanup projects. Asbestos remains in many products and buildings, in some cases in hazardous forms in other cases probably not.
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That asbestos remains a controversial material was evident in a New York Times article reported in February 2015. There the Times reported
The following text is Adapted from Rosato (1959) p. iii-iv & 1-36.  © 2013 InspectApedia.com
D. V. Rosato, Engineering Consultant Newton, Massachusetts (1959), edited, adapted, expanded (1985-2013)
This book discusses the many varied applications of asbestos. Its purpose is to provide background as well as factual information on the uses of asbestos. Asbestos is utilized in a wide range of products, though its identity is often obscured. The discussion in this book is primarily concerned with the more familiar specialized products.
Asbestos can be classified both as an old product and as a new one. History has justified its usefulness. The accelerated pace at which technology is advancing in this atomic and space age has created many new demands on basic materials and the need for developing new and improved products at a more rapid rate.
The technological advances in the use of asbestos have produced some large and important industries. This does not mean that asbestos will supplant other established materials, any more than it can be expected that other products will eliminate asbestos.
The possibility of new uses for asbestos is far from exhausted. Because of such technical advances and scientific research, diversified products have been developed. Valuable new properties of asbestos have been determined, which in turn account for its many new applications. These, as well as improved products, are included in this volume.
Photo at left, Asbestos cement pipe. (Courtesy Johns-Manville Corp.)
The increase in asbestos products in the past 2,000 years has been a milestone in world growth. The atomic age has been reached as a result of the achievements made in working with such materials as asbestos. Asbestos used in conjunction with new chemicals continues to make important contributions to industry. The combined effort of special military agencies and industry has resulted in its continual growth in diversified fields; ingenious methods have been developed to utilize this material.
This book will serve as a guide to various branches of industry—research and development groups, manufacturers, educational institutions, market research groups, and sales management. Its purpose is to better acquaint industry with asbestos products in the fields of building materials, insulation, electrical units, chemical units, asbestos-cements, filters, friction materials, packings, adhesives, lubricants, plastics, machinery, paper, medicine, etc.
In order to do this, it is necessary that a review be made of the types of materials that are available, their properties, and the methods of manufacturing them. Such a review will help the reader to have a better understanding of the variables which exist in working with this material. In most applications, where asbestos is used, the products are superior to other materials.
This book is designed to present the various industrial applications, and an over-all view of the methods of fabrication. It is hoped that this book will stimulate further re- search in the use of asbestos, particularly more fundamental basic research.
Material has been derived from many sources. The data are based on observation and published references. The author wishes to thank the many companies that have contributed to the preparation of this volume.
- D.V. Rosato, Newton Mass, May, 1959 [edited, expanded, illustrated, D J Friedman 1985 - 2013]
The Origin and Nature of Asbestos
Asbestos is the name given to the serpentine and amphibole groups of fibrous inorganic minerals that occur in different forms and in different parts of the world. The most important group is chrysotile which represents approximately 95 per cent of the total world production of all asbestos.
Photo at left: asbestos paper on HVAC ducts served as both insulation and a seal against air leaks. See ASBESTOS PAPER DUCT INSULATION for details.
The most important deposits are in Canada. Asbestos has been recorded in literature from the days of the Romans, but it was not mined and used in large quantities until the deposits in Canada were made available in 1878. Canada produces approximately 60 per cent of the world's asbestos with 95 per cent being of the chrysotile type.
Geologists refer to asbestos as material transformed from special rocks (serpentine), twisted and squeezed by prehistoric volcanoes millions of years ago. Masses of molten rock passed through the earth's crust; mineral-rich ocean waters rushed through the cracks and crevices. As the earth's internal heat and pressure developed, these openings filled up with crystals developed from the passing water.
The asbestos filled cracks and crevices are referred to as veins in the rock. These veins sometimes occur on the surface of the earth. But more frequently, they are deep in the ground. Asbestos is obtained from surface or tunnel mining. After it has been mined, the tightly packed asbestos fibers go td mills where they are fiberized and cleaned.
Chrysotile is a serpentine mineral and the most important form of asbestos. Its formula is 3MgO.2SiO2.2H20. Its main chemical compositions are Si02 and MgO. Other compositions of asbestos include 1120, FcO, Fe 2 0 and Al23.
Asbestos is a mineral; however, it can be separated into the finest man made or natural flexible fiber. Single fiber diameters can be obtained as fine as 0.0000007 in. It will not burn or rot; it resists heat and chemicals.
Shown at left, asbestos ore. Rosato (1959)
Because it combines these properties with other advantageous properties, asbestos is now an important industrial product for both regular and specialized products, the manufacture of which constitutes a vast industry. In most cases, asbestos loses its identity in the finished product; in more than 95 per cent of its applications, it is combined with other products to produce such items as tile, gaskets, plastics, cements, and filters.
The [asbestos] fiber-bearing rocks contain [asbestos] fibers of various lengths. The shorter fibers are more abundant; they are used in the largest single asbestos industry; i.e., for such asbestoscement products as siding shingles, fiat sheets, roofing shingles and corrugated sheets.
The longer asbestos fibers are used primarily in the manufacture of such textile products as yarn, cloth, tape, felt and lap. These constitute the second largest use for asbestos. The principal method of obtaining asbestos for the textile industry involves hand picking operations at the mine. However, special fiberizing processes at the textile mill are of prime importance in the manufacture of the end products.
Origin of Asbestos
One of the theories of the formation of asbestos involves the result of volcanic activity which occurred many hundreds of thousands of years ago. The igneous rocks had acidic inclusions that formed granites and feldspar dikes. The basic inclusions formed dunite which eventually formed peridotite and pyroxene peridotite after coming in contact with olivine and oxides.
Through the ages, these rocks passed through various stages of physical and chemical changes and formed minerals known as serpentine. This change occurred when high pressure caused cracks in the rock. In turn, these cracks were filled with hot ground waters derived from the infiltration of rain or surface waters. The continued infiltration of this water under heat and pressure caused the water to become contaminated with various minerals. Crystals developed and were deposited in the cracks.
The rock formation in Canada is a variety of olivine which is composed of iron, magnesia, and silicate. Water containing carbon dioxide and salt in solution penetrated the rocks. This gradual flow of highly contaminated water changed the original rock from an iron-containing mineral to a magnesia-silica-iron solution. According to the geologist, this reaction took place thousands of feet below present elevation.
It is believed that asbestos developed deep within the earth where conditions of high pressure and heat existed. Since in the case of the North American Continent asbestos is found on the surface, it is assumed that the glaciers or massive ice formations removed the overburden of earth.
The importance and commercial value of asbestos is attributed both to its incombustibility and to its unique structure. It is fibrous, having been created by a natural process which man has not been able to reproduce. In a sense, it is a mineral silk, un-decayed and unaltered by time or weather.
Asbestos is an enemy of heat, flame, chemicals and acids. In addition, it is resistant to moisture and corrosion. Asbestos fibers can be individually fiberized and handled in a manner similar to such fibers as those of animal origin ( wool and silk) and those of vegetable origin (cotton and flax). To the physicists and scientists, asbestos is of especial interest, inasmuch as it is both fibrous and crystalline.
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