Asbestos chemical compositions

W, X, Y each represent cationic sites of different geometries (12). From this generic representation, the chemical composition of the amphibole asbestos can be given as foUows ... 

The fiber extraction (milling) process must be chosen so as to optimize recovery of the fibers in the ore, while minimizing reduction of fiber length. Since the asbestos fibers have a chemical composition similar to that of the host rock, the separation processes must rely on differences in the physical properties between the fibers and the host rock rather than on differences in their chemical properties (33). 

Asbestos constitutes several types of hydrated silicate mineral fibers. The types of asbestos, their chemical compositions, and CAS Numbers are presented in Table 3.8.1. These substances occur in nature in rocks, silicate minerals, fibrous stones, and underground mines. This class of substances exhibits unique properties of noncombustibility, high resistance to acids, and high tensile strength for which they were widely used in many products, including floor and roofing tiles, cement, textiles, ropes, wallboards, and papers. Because of the health hazards associated with excessive exposure to asbestos, the use of these substances is currently banned. 

Asbestiform—Possessing the properties of asbestos. Minerals of specific chemical compositions can have asbestiform varieties that are fibrous in nature (e.g., crocidolite and amosite are the asbestiform varieties of the amphibole minerals, reibeckite and gmnerite tremolite and actinolite may be either asbestiform or nonasbestiform)... 

Samples of the fibrous amphibole in the Libby vermiculite ore, popularly referred to as tremolite asbestos, were recently analyzed by U.S. Geological Survey scientists. On the basis of variable chemical composition, several different mineral names were assigned to the samples winchite, richterite, tremolite, actinolite, ferro-edenite, and magnesio-arfvedsonite. All of these are classified as amphibole minerals. 

Meeker GP, Brownfield IK, Claik RN, et al. 2001. The chemical composition and physical properties of amphibole from Libby, Montana a progress report. Poster presentation, 2001 Asbestos Health Effects Conference. Sponsored by U.S. Environmental Protection Agency. May 24-25, 2001. San Francisco,... 

Asbestos-filled compositions have high chemical, mechanical and thermal resistance and outstanding dielectric properties. 

The different chemical composition and structures of chrysotile and amphibole asbestos have a considerable influence on their physical properties. 

The chemical composition of indoor particles is very complex and depends on the particle origin as well as on any postformation processes in which the particle is involved. Some types of particles, like asbestos and glass fibres, consist of inorganic materials, while other types, like cellulose fibres, are purely organic. The most important chemical properties of particles include... 

All of the above forms of asbestos belong to either the Serpentine or Amphibole mineral groups and have different chemical compositions and hence different associated properties. All have excellent heat insulating properties and are relatively incombustible, whilst some are flexible or have high tensile strengths, or resistance to acids and alkalis. 

The serpentine group of minerals, which include chrysotile asbestos, are almost identical in composition. The chemical composition of unit cell is Mg6(OH)8Si40io. Chrysotiles have layered or sheeted crystal structure containing a silica sheet of (Si20s) in which silica tetrahedra point one way (Streib 1978). A layer of brucite, Mg(OH)2, joins the silica tetrahedra on one side of the sheet structure. Two out of every three —OH are replaced by oxygen atoms. X-ray and electron microscope studies indicate... 

TABLE 10.1 Asbestos Types and Their Chemical Compositions... 

As a consequence of their variation in chemical composition, the toxicological properties of MMMF vary over a big range. Their carcinogenic potency increases in the series normal glass wool < rock wool < slag wool < ceramic fibers < asbestos. 

The nominal chemical compositions for the asbestos minerals were given in Section 1. Compared to cleavage fragments of the same minerals, asbestiform fibers possess a high tensile strength along the fiber axis. They are... 

Resistance of plastic piaterials to chemically active media may be affected by the presence of additives such as asbestos fibers [8], lubricants [2], or fillers. Effects of fillers depend on their nature and on their content in the plastic material [9-12]. But, in general, the resistance of a plastic to chemically or physically active media depends above all on the chemical composition and the structure of the basic polymer, on the temperature, and on other factors. 

A second class of silicate mineral called asbestos is a serpentine mineral, chrysotile. It is a magnesium silicate hydrate, Mg6[Si40n(0H)6]H20, with a chemical composition similar to talc, Mg3Si40io(OH)2. There is at least a plausible argument that chrysotile should not have been included with other minerals named asbestos from chemical, health, and legal considerations. There is small doubt that the amphiboles are much more likely to cause difficulties. A study of two cement pipe plants in New Orleans revealed some interesting results. In one... 

Synthesized FFS by their chemical composition (Table 5), structure (Table 6, Fig 11), and physical-chemical properties (Table 7) related to NaMg-arfvedsonite asbestos (Hodgson, 1965 Chigareva, 1967 Grigor eva et al., 1975). Crystallochemical formulas of fibrous fluorosilicates synthesized in serpentinite-, dunite-, peridotite- and p)rroxnite-containmg blends corresponded respectively to ... 

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