Asbestos mining/production

Asbestos Construction, asbestos mining and milling, production of frictinn products (brake Linings, etc.), and cement Pleura and bronchus (lungs) and peritoneum... 

Close to an asbestos mine or factory, levels may reach 10,000 fibers/m (0.01 fibers/mL) or higher. Levels could also be above average near a building that contains asbestos products and that is being tom down or renovated or near a waste site where asbestos is not properly covered up or stored to protect it from wind erosion. 

The production volume of asbestos mines in the United States has decreased substantially from a peak of... 

Workers involved in mining of asbestos or minerals contaminated with asbestos or manufacturing or using asbestos-containing products may be occupationally exposed to elevated levels of asbestos. Average asbestos fiber concentrations (>5 pm) in the Quebec chrysotile mining industry declined maikedly from 16 f/mE in 1973 to 2 f/mL in 1978 and has remained below 2 f/mL between 1978 and 1994 (WHO 1998). 

The price of phosphate fibers and most manufactured substances can never compete with mined products such as asbestos, nor can it compete in performance in many areas where indestructibleness is a desirable property. Mined products have had to withstand the ravages of time to have survived. They have had centuries to approach a minimum free energy and, until disturbed, they are likely to maintain their current status. This, of course, excludes organic materials that have been... 

Early demand for chlorine centered on textile bleaching, and chlorine generated through the electrolytic decomposition of salt (NaCl) sufficed. Sodium hydroxide was produced by the lime—soda reaction, using sodium carbonate readily available from the Solvay process. Increased demand for chlorine for PVC manufacture led to the production of chlorine and sodium hydroxide as coproducts. Solution mining of salt and the avadabiHty of asbestos resulted in the dominance of the diaphragm process in North America, whereas soHd salt and mercury avadabiHty led to the dominance of the mercury process in Europe. Japan imported its salt in soHd form and, until the development of the membrane process, also favored the mercury ceU for production. 

Occurrences in the United States were known as early as 1698 with numerous finds along Brandywine Creek in Pennsylvania (Frondel, 1988). The celebrated purse made from asbestos that Benjamin Franklin took to London in 1724, and which now resides in the British Museum of Natural History, may have been made of long-fiber asbestos from Newbury, Massachusetts. As a journeyman printer, Franklin made paper from asbestos, as did many Europeans. It was also used in making lamp wicks and cloth. Commercial mining in the United States took place some time after the first discovery of asbestos on Staten Island, New York, in 1818. (Asbestos continued to be mined at the site until 1876.) By 1825 more than seventy localities were known to produce asbestos in the United States (Robinson, 1825). However, as early as 1804 Jameson had recorded the mineralogy of the species and listed the numerous university, societal, and private mineral collections containing specimens of asbestos from U.S. localities and asbestos products of local manufacture. 

Two to 3 percent of the world s total asbestos production has been of the crocidolite variety, most of which has come from South Africa. Western Australia was a minor producer of crocidolite between 1944 and 1966. All amosite has been mined in the Transvaal Province of South Africa (2 to 3 percent of the world total). The only significant anthophyllite production came from Finland, where about 350,000 tons were mined between 1918 and 1966. Table 2.6 lists the composition, optical, and diffraction characteristics of the six asbestos minerals. More information on individual mineral species can be found in the references accompanying the sections on serpentine and amphibole types. Discussion of the geology, terminology, and exploitation of the several types of asbestos can be found in Ross (1981). 

Asbestos became a popular commercial product because it is strong, will not bum, resists corrosion, and insulates well. When mined and processed, asbestos is typically separated into very thin fibers. When these hbers are present in the air, they are normally invisible to the naked eye. Asbestos fibers are commonly mixed during processing with material that binds them together so that they can be used in many different products. Because these fibers are so small and light, they remain in the air for many hours if they are released from ACM in a building. When fibers are released into the air they may be inhaled by people in the budding. 

Industrial processes, such as mUling and mining, construction work, and the burning of wood or fossil fuel, generate particulates that can be directly toxic or can serve as vectors for the transfer of bound material, such as sulfuric acid, metals, and hydrocarbons, into the lungs. Natural products such as pollen, anthrax spores, and animal dander can elicit toxic reactions on inhalation or skin contact. The inhalation of asbestos, silica, or coal dust can cause pneumoconiosis, which may develop into serious lung disease. The size of the particle, ventilatory rate, and depth of breathing will determine the extent of pulmonary deposition. 

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. 

From early times working people have been exposed to toxic substances ranging from minerals and metals that were mined and then worked into products, for example asbestos, lead, and mercury, to more complex chemicals produced or used in the synthesis of the countless products we now enjoy, such as plastics and drugs. There are numerous chemicals to which workers can now be exposed, some of which may be toxic. 

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