- High temperature ablation of kaolinite layered silicate/phenolic resin/asbestos cloth nanocomposite
Ahmad Reza Bahramian, Mehrdad Kokabi, Mohammad Hossein Navid Famili and Mohammad Hossein Beheshty.
Journal of hazardous materials, Vol. 150, No. 1, Jan 15 2008, pp. 136-145.
The successful return of re-entry space vehicle, which is subjected to severe aerodynamic heating, is largely accompanied by some provisions to reduce the heat transfer to the structure. Heat shield is the best protection means which undergoes physical, chemical, and mostly endothermal transformations. The objective of this work is to investigate the ablating, charring, and thermal degradation behaviour of heat shield resol-type phenolic resin/kaolinite/asbestos cloth nanocomposite by oxyacetylene flame test with an external heat flux of 8 x 10(9)W/m(2) and 3000 K hot gas temperature and thermal analyzer techniques. Kinetic parameters of thermal degradation and temperature distribution at the back surface of the nanocomposite heat shield were determined and compared with that of composite counterpart.
- The geology of asbestos in the United States and its practical applications
Bradley S. Van Gosen.
Environmental & Engineering Geoscience, Vol. 13, No. 1, Feb 2007, pp. 55-68.
Recently, naturally occurring asbestos (NOA) has drawn the attention of numerous health and regulatory agencies and citizen groups. NOA can be released airborne by (1) the disturbance of asbestos-bearing bedrocks through human activities or natural weathering, and (2) the mining and milling of some mineral deposits in which asbestos occurs as an accessory mineral(s). Because asbestos forms in specific rock types and geologic conditions, this information can be used to focus on areas with the potential to contain asbestos, rather than devoting effort to areas with minimal NOA potential. All asbestos minerals contain magnesium, silica, and water as essential constituents, and some also contain major iron and/or calcium. Predictably, the geologic environments that host asbestos are enriched in these components. Most asbestos deposits form by metasomatic replacement of magnesium-rich rocks. Asbestos-forming environments typically display shear or evidence for a significant influx of silica-rich hydrothermal fluids. Asbestos-forming processes can be driven by regional metamorphism, contact metamorphism, or magmatic hydrothermal systems. Thus, asbestos deposits of all sizes and styles are typically hosted by magnesium-rich rocks (often also iron-rich) that were altered by a metamorphic or magmatic process. Rock types known to host asbestos include serpentinites, altered ultramafic and some mafic rocks, dolomitic marbles and metamorphosed dolostones, metamorphosed iron formations, and alkalic intrusions and carbonatites. Other rock types appear unlikely to contain asbestos. These geologic insights can be used by the mining industry, regulators, land managers, and others to focus attention on the critical locales most likely to contain asbestos.
- Asbestos mineral analysis by UV Raman and energy-dispersive X-ray spectroscopy
Renate Petry, Remigius Mastalerz, Stefan Zahn, et al.
Chemphyschem: a European journal of chemical physics and
physical chemistry, Vol. 7, No. 2, Feb 13 2006, pp. 414-420.
The applicability of a UV micro-Raman setup was assessed for the rapid identification of fibrous asbestos minerals using 257 and 244 nm laser light for excitation. Raman spectra were obtained from six asbestos reference standards belonging to two basic structural groups: the serpentines (chrysotile) and the amphiboles (crocidolite, tremolite, amosite, anthophyllite, and actinolite). The UV Raman spectra reported here for the first time are free from fluorescence, which is especially helpful in assessing the hydroxyl-stretching vibrations. The spectra exhibit sharp bands characteristic of each asbestos species, which can be used for the unambiguous identification of known and unknown asbestos fibres. Evident changes of the relative band intensities sensitively reflect the chemical substitutions that typically occur in asbestos minerals. The elemental composition of the asbestos reference samples was analysed by using a scanning electron microscope equipped with an energy-dispersive X-ray (EDX) spectrometer. The discussion of the experimental results in terms of EDX analysis sheds new light on the structural and vibrational consequences of cation distribution in asbestos minerals.
- Naturally occurring asbestos
Marc A. Hendrickx.
Australian Geologist, Vol. 141, 2006, pp. 27-29.
- Reported historic asbestos prospects and natural asbestos occurrences in the central United States
Bradley S. Van Gosen.
Open-File Report - U.S.Geological Survey, Vol. OF 2006-1211,
This map and its accompanying dataset provide information for 26 natural asbestos occurrences in the Central United States (U.S.), using descriptions found in the geologic literature. Data on location, mineralogy, geology, and relevant literature for each asbestos site are provided. Using the map and digital data in this report, the user can examine the distribution of previously reported asbestos occurrences and their geological characteristics in the Central U.S. This report is part of an ongoing study by the U.S. Geological Survey to identify and map reported natural asbestos occurrences in the U.S., which began with U.S. Geological Survey Open-File Report 2005-1189 (http://pubs.usgs.gov/of/2005/1189/). These reports are intended to provide State and local government agencies and other stakeholders with geologic information on natural occurrences of asbestos in the U.S.
- Asbestos from Libby Montana; compositions and morphologies that don't fit current asbestos definitions; Abstracts of the 15th annual V. M. Goldschmidt conference
G. P. Meeker, H. A. Lowers and I. K. Brownfield.
Geochimica et Cosmochimica Acta, Vol. 69, No. 10, May 2005, pp. 189.
- Belvidere asbestos mine; site suitability for CO (sub 2) sequestration through mineral carbonation; a field and geochemical study; Vermont Geological Society's spring meeting [modified]
The Green Mountain Geologist, Vol. 32, No. 2, 2005, pp. 11-12.
- Geology of naturally occurring asbestos in California; Geological Society of America, Cordilleran Section, 101st annual meeting; American Association of Petroleum Geologists, Pacific Section, 80th annual meeting
John P. Clinkenbeard and Ronald K. Churchill.
Abstracts with Programs - Geological Society of America, Vol. 37, No. 4, Apr 2005, pp. 37.
California has experienced a rising concern over potential public exposure to naturally occurring asbestos (NOA) in recent years. Consequently, geologists in California are increasingly being called upon to evaluate the NOA potential of property prior to land-use decisions, land acquisition, or property development. While economic deposits of the asbestos minerals are rare, small non-economic occurrences of chrysotile or amphibole asbestos, which may be of environmental concern, may be present in a variety of rock types and geologic environments around the State. In California, NOA is most commonly associated with serpentinite and serpentinized ultramafic rocks. Other rock types in which NOA has been reported to occur in California include: gabbro, granite, schist, limestone, dolomite, shale, slate, amphibolite, albitite, and nickel laterite. The occurrence of asbestos in these rock types is less common than the occurrence in serpentinite/ultramafic rocks. Chrysotile occurs most commonly in serpentinites and serpentinized ultramafic rocks but may also occur in altered or metamorphosed mafic rocks or in metamorphosed carbonate rocks. The amphibole asbestos minerals (tremolite, actinolite, anthophyllite, riebeckite, and cummingtonite-grunerite) also occur in and immediately adjacent to serpentinites and serpentinized ultramafic rocks and in a variety of other metamorphosed rocks including metamorphosed mafic plutonic rocks, mafic volcanic rocks, ironstones, iron-rich cherts, carbonate rocks, and granitic rocks. In many of these occurrences, NOA may be more likely to found at geologic boundaries or in fault or shear zones where fluid flow has been enhanced. Any rock that has a chemical composition that would allow the formation of amphibole or serpentine minerals may contain asbestos if physical conditions have been favorable at some point in the rock's history. In addition to occurring in a variety of metamorphic rocks, asbestos minerals may also occur in sedimentary rocks, soils, or sediments derived from asbestos containing parent materials.
- Geochemistry of amphibole asbestos from northeastern Portugal and their environmental impact; Italia 2004; 32nd international geological congress; abstracts
Rui Teixeira, Ana Neiva and Elisa Gomes.
International Geological Congress, Abstracts = Congres Geologique
International, Resumes, Vol. 32, Part 1, Aug 2004, pp. 638.
- Raman spectroscopy as a rapid method for the identification of asbestos; Italia 2004; 32nd international geological congress; abstracts
Caterina Rinaudo, Daniela Gastaldi and Elena Belluso.
International Geological Congress, Abstracts = Congres Geologique
International, Resumes, Vol. 32, Part 2, Aug 2004, pp. 1435.
- Reconstruction of a Century of Airborne Asbestos Concentrations
J. S. Webber, K. W. Jackson, P. P. Parekh and R. F. Bopp.
Environmental science & technology, Vol. 38, No. 3, 1 Feb 2004, pp. 707-714.
Airborne asbestos concentrations have been reconstructed for the entire 20th century for the first time through a combination of paleolimnological methods, particle-separation techniques, and analytical transmission electron microscopy. Pb concentrations and respirable aerosol mass concentrations in air and sediments yielded collection efficiencies of similar to 3000 m super(3) of air per gram of lake sediment. Airborne concentrations of chrysotile, the most common type of asbestos, reconstructed from control lake sediments echoed chrysotile's usage during the 20th century, with the highest concentrations mid-century ( similar to 0.1 fibers/cm super(3)) and then decreasing in the last quarter century. Reconstructed airborne concentrations of anthophyllite asbestos, a byproduct of local talc mining and milling, increased from <0.004 to 0.022 fibers/cm super(3) from 1846 to 1967. These anthophyllite concentrations during the similar to 100-year period of talc mining correlated well (r super(2) = 0.80, p < 0.01) with annual production of local talc and were much higher (p = 0.004) than concurrent concentrations in a control lake located upwind of the mines and mills. All of the chrysotile and more than 70% of the anthophyllite asbestos fibers were too narrow to be detected by phase-contrast light microscopy, the method used to measure airborne fiber concentrations before similar to 1980.