This is a Continuation-In-Part of U. In the petrochemical industries, large quantities of fluids are transferred through piping. Often these fluids must be maintained at temperatures above ambient to avoid freezing or to prevent undue increase in viscosity. One common means of maintaining the desired temperature conditions in the pipeline is to supply enough heat energy to balance the heat losses by means of a heat-supplying "tracing," mechanically fastened to the piping. The tracing may be a tube through which a hot fluid, like water, mineral oil or steam, is passed or it may be a cable of resistance wires enclosed in a metal jacket.
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asbestine ball millVIDEO ON THE TOPIC: BRAKE-LINER SUPPLIER MANUFACTURER INDIA
NCBI Bookshelf. Carbon Black, Titanium Dioxide, and Talc. The mineralogy of airborne particles in talc mines is restricted by that of the deposit and associated rocks. Therefore, mines and mills provide an opportunity to characterize exposure to one specific source of talc mineralogically.
In contrast, the mineralogy of talc in an industrial setting where talc products are used may be difficult to characterize, because many different sources of talc are available for almost every application. Industrial talcs are quite variable in their talc content and in the identity and proportion of other minerals that they contain. In addition, talc is part of a complex mixture of materials in user industries.
Talc particles are normally plate-like. When viewed under the microscope in bulk samples or on air filters, they may appear to be fibres and have been identified as such. Asbestiform talc fibres are very long and thin and occur in parallel bundles that are easily separated from each other by hand pressure. Asbestos is a commercial term that describes six minerals that occur in the asbestiform habit: actinolite, anthophyllite, chrysotile, grunerite, riebeckite and tremolite IARC, Similarly to talc, these six minerals occur more commonly in a nonasbestiform habit, and may also be elongated without being asbestiform.
Actinolite, anthophyllite and tremolite may occur in some talc deposits; when asbestiform, they constitute asbestos and, when not asbestiform, they are referred to as mineral fragments or cleavage fragments.
Rocks or mineral composites that contain talc mineral include agalite, potstone, soapstone and talcite. Steatite originally referred to a rock that is relatively pure talc; today, it denotes a ceramic body with a high talc content that is used as an electrical insulator. The talc that is used in such applications is known as steatitic talc. French chalk is soft massive talc Piniazkiewicz et al. Talc has also been referred to as snowgoose, agalite and kerolite.
Talcum powder is cosmetic-grade talc Zazenski et al. The original X-ray spectra of talc Gruner, ; Hendricks, indicated that mineral talc had a monoclinic structure. Later investigations Ross et al. The structsheet arrangement of silicon-oxygen tetrahedral groups linked in a common plane. Each silicon—oxygen tetrahedron shares three planar oxygen atoms with its neighbouring tetrahedra; the fourth oxygen, the apex of the tetrahedron, is not shared.
Two such sheets are orientated so that unshared apical oxygen atoms face each other. The sheets are bonded by magnesium atoms that are coordinated octahedrally by two oxygen atoms from each tetrahedral sheet and two hydroxyl groups.
This structural arrangement results in a double-sheet structure in which the valence demands of the constituent atoms are completely satisfied without interlayer cations; these double-sheet units are held together only by weak van der Waal's bonds.
The double-sheet units are easily separated by slight forces that result in a perfect cleavage direction in the basal plane Rohl et al. The structure of talc is depicted in Figure 1.
Colour : Pale to dark green or greenish grey to black; also white, silvery-white, grey, brownish. The indices of refraction increase with iron content. Talc particles are normally thin and plate-like, but the size of the individual plates varies among different bodies of ore. When viewed under the microscope on end, talc platelets may appear as fibres Cralley et al.
These are not true fibres and should not be confused with asbestiform talc. Asbestiform talc is formed when talc plates elongate parallel to the a axis within the plate to form true ribbon-like fibres of talc. These fibres may occur in an asbestiform habit consisting of bundles of narrow fibres randomly oriented around the axis of elongation c axis. When expressed in the standard oxide form, the ideal chemical composition is: No talc is ideal, and small amounts of aluminium and iron are common impurities.
Aluminium may substitute for both magnesium and silicon; iron II and iron III may substitute for magnesium. Talc that has almost all magnesium substituted by iron is called minnesotaite and is abundant in the iron formations of Minnesota, USA Deer et al. Fluorine is the most common substitution for the hydroxy group Petit, Small amounts of nickel, chromium, calcium, potassium, sodium and manganese are also found in the octahedral sites while titanium may substitute for silicon in the tetrahedral site.
Table 1. Solubility : The solubility of talc has been described in detail by Jurinski and Rimstidt The reader is referred to Section 4 for a detailed description of the kinetics of deposition and clearance.
Hydrothermal fluids may be derived from fluids that migrate during retrograde or prograde regional metamorphism or from contact metamorphism that is associated with nearby or distant intrusive igneous rocks. The chemical and mineral compositions of talc from various locations are shown in Tables 1.
Talc deposits, the protoliths of which are ultramafic or mafic rocks, are abundant in number but small in total production. They are found in discontinuous bodies in orogenic belts, such as the Alps, the Appalachians and the Himalayas, and form during the regional metamorphism that accompanies orogenesis. These deposits may contain trace amounts of nickel, cobalt and chromium that are derived from their ultramafic protolith.
One major talc deposit in eastern USA contains substantial amounts of nickel up to 0. Nickel-substituted talc is also associated with serpentine bodies, at up to 0. Quartz is uncommon in talc that has mafic or ultramafic protoliths and the fluorine content is generally low Ross et al. Chlorite and amphiboles are usually associated with this type of talc deposit although they are commonly separated in space from the talc ore Vermont.
The amphiboles may or may not be asbestiform, depending on the local geological history. Talc deposits formed from the alteration of carbonate and sandy carbonate such as dolomite and limestone are the most important in terms of world production.
Talc derived from magnesium carbonate may contain quartz. Van Gosen et al. In some deposits in the second group, amphiboles may be very abundant, especially those formed during high-temperature regional metamorphism of impure dolomites.
Gouverneur District New York State talc that is currently marketed under the trade name Nytal is a unique industrial mineral product that can readily be distinguished from all other commercially available industrial talcs based on its mineral content. Vanderbilt Company, The tremolite, anthophyllite and serpentine occur as mineral fragments and not as asbestiform fibres. Tremolite from this deposit has been characterized in detail Campbell et al. Nytal also contains asbestiform fibres of talc and talc intergrown on a nanoscale with amphibole Wylie et al.
Wylie et al. Products from other mines in this district before contained different proportions of anthophyllite and tremolite, which may be asbestiform Chidester et al.
Because talc deposits are formed from different protoliths under many different geological conditions, each talc deposit has a combination of mineralogy and mineral habit that is distinctive and, in many cases, unique. The most common minerals found in talc products include chlorite, magnesite, dolomite, tremolite, anthophyllite, serpentine and quartz. However, many other minerals have been reported; these are given in Table 1.
Some of these minerals are beneficial to certain applications such as tremolite in ceramics. The variability in the chemical composition of talc ore, talc mineral products and talc rock primarily reflects their mineral composition see Table 1. Talc ores may be processed by a variety of techniques that include selective mining, hand sorting and milling by roller mills, hammer mills, ball mills, fluid energy mills and jet mills and are classified and separated from other minerals by froth flotation or magnetic separation.
Some may be treated with acid and calcined. The particle sizes of talc and the abundance of the associated minerals are determined by characteristics of the ore, methods of processing, and the duration of grinding. Grinding breaks the talc platelets along and disaggregates the particles; prolonged grinding may destroy the crystallinity Sanchez-Soto et al.
Roller mills tend to preserve the platy structure and different types of milling affect properties such as flatness, surface roughness, roundness, width and elongation Yekeler et al. Talc particles are platy, and sizes reflect the dimension parallel to the plate; data are not available on the thinness of the plates. Lower-purity talc is used in roofing material, patching compounds, flooring and fertilizers Piniazkiewicz et al.
Particle sizes, colour and nature of associated minerals also vary among these applications. Chlorite has similar optical properties. Anthophyllite and sepiolite have chemical compositions that are very similar to talc and require quantitative chemical analysis to differentiate them, including the use of well characterized standards in the case of dispersive X-ray analysis used in conjunction with electron microscopy.
Identification of mixed mineral assemblages by X-ray diffraction may be difficult because of pattern overlap Krause, and X-ray diffraction cannot distinguish asbestiform minerals from other habits. Particle size distributions that are determined by settling underestimate the abundance of larger particles and overestimate the number of smaller particles because the platy structure results in longer settling times for talc compared with spherically shaped particles of equivalent size.
Computer-controlled scanning electron microscopy has been used to provide a more accurate size distribution. Determination of the respirable fraction of bulk materials by these two methods differs significantly Zazenski et al. The standard methods for the analysis of airborne exposures in an occupational setting where asbestos is known to be present include those of the Health and Safety Executive and the Occupational Safety and Health Administration They do not determine the mineral identity of the particles counted.
In a mining environment where many minerals form elongated fragments, the results of fibre counts can be difficult to interpret.
In bulk samples of talcum products, for example, Cralley et al. Conversion of fibre counts to gravimetrically based exposure metrics is complicated as this will depend on the particle size. Oestenstad et al. All gravimetric measurements to monitor exposure to talc in occupational settings are taken from samples of respirable dust particles. The reader is referred to the Glossary and the monograph on carbon black for further details.
Talc deposits result from the transformation of existing rocks under hydrothermal activity and are classified according to the parent rock from which they derive. This wide diversity of origins and types of deposit naturally gives rise to a wide variety of ores and product grades that differ according to their mineralogical composition, colour and crystalline structure microcrystalline or lamellar Luzenac, ; EUROTALC, ; Industrial Minerals Association-Europe, World production of talc and pyrophyllite in both and was estimated to be 8.
Of the total production, approximately 2. The Republic of Korea was the leading producer of pyrophyllite, followed by Japan and Brazil. World production of talc in tonnes unless otherwise specified ,. The properties of mineral talc platyness, softness, hydrophobicity, organophilicity and inertness and the mineralogical composition of talc products govern their specific applications in many industries and processes including paint, polymers, paper, ceramics, animal feed, rubber, roofing, fertilizers, cosmetics and pharmaceuticals.
Patented Jan. Abernathy, Rochester, N. Blades, Hor-nell, N. This application is a division of my copending application of the sametitle Serial No. Another object of the invention is to provide such a material which can beproduced in any color of any desired brilliance or delicacy, and in which the color is retainedwithout fading, dulling or severe weathering or use.
US3972821A - Heat transfer composition and method of making - Google Patents
The present invention relates to a method for modifying asbestos, and more particularly to a method for modifying asbestos using microwave technology. Asbestos has excellent properties such as heat resistance, fire resistance, soundproofing, chemical resistance, wear resistance, insulation, and corrosion resistance. Among the asbestos, crocidolite, amosite, and chrysotile are frequently used, and the amount of chrysotile used is the largest due to the delay of legal regulations in Japan. As building materials, corrugated asbestos slate, residential asbestos slate, asbestos cement board flexible board, flat plate, soft board, etc.
Asbestos - Wikipedia, The Free Encyclopedia
Bernstein, Brookfleld, and Thomas F. Mika, Chicago, The present invention relates to a gasket construction and more particularly to a novel gasket material and in the novel means and method of manufacture of this material. In the manufacture of this novel gasket material the asbestos millboard is first produced upon a paper making machine in which the fiber and binder are uniformly distributed throughout the entire sheet to thereby insure the production of a continuously uniform product. After the asbestos millboard is produced it is then combined with a reinforcing core or backing which may be of perforated or expanded metal or other material suitable for the purpose. By thus completely filling these grommets or flanges with the bonded asbestos, there is no danger of collapse of the grommets or flanges when in use and when subjected to the hot gases in the combustion chambers, one cause of gasket breakdown.
Physico-chemical aspects of methods for obtaining mortars, concrete, artificial stones or ceramics , e. Treatment including defibrillating of materials such as fillers , agglomerated or waste materials, or refuse to enhance their filling properties in mortars, concrete or artificial stone. After- treatment of artificial stones, mortars, concrete and ceramics , e. Processing powders of inorganic compounds in preparation to the manufacturing of ceramic products. Mechanical features relating to the working of mortars, concrete, stone, clay-wares or ceramics , e. Compositions containing free metal bonded to carbides, diamond, oxides, borides, nitrides, silicides, e. Hydraulic hardening materials , e.
Dictionary of Ceramic Science and Engineering
NCBI Bookshelf. Carbon Black, Titanium Dioxide, and Talc. The mineralogy of airborne particles in talc mines is restricted by that of the deposit and associated rocks.
AskDefine Define amianthus Printer Friendly. English Noun a type of asbestos with long, soft, thin fiber s. Asbestos is a group of mineral s with long, thin fibrous crystal s. The word "asbestos" is derived from a Greek adjective meaning inextinguishable. The Greeks termed asbestos the "miracle mineral" because of its soft and pliant properties, as well as its ability to withstand heat. Asbestos became increasingly popular among manufacturers and builders in the late 19th century due to its resistance to heat, electricity and chemical damage, its sound absorption and tensile strength. When asbestos is used for its resistance to fire or heat, the fibers are often mixed with cement or woven into fabric or mats. Asbestos is used in brake shoes and gasket s for its heat resistance, and in the past was used on electric oven and hotplate wiring for its electrical insulation at elevated temperature, and in buildings for its flame-retardant and insulating properties, tensile strength , flexibility, and resistance to chemicals. Unfortunately, this "miracle material" is now known to be highly toxic. The inhalation of asbestos fibers can cause serious illnesses, including mesothelioma and asbestosis. Since the mid s, many uses of asbestos have been banned in many countries.
US2330106A - Gasket material - Google Patents
InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website. This document assists building buyers, owners or inspectors who need to identify asbestos materials or probable-asbestos in buildings by simple visual inspection. We provide photographs of asbestos containing materials and descriptive text of asbestos insulation and other asbestos-containing products to permit identification of definite, probable, or possible asbestos materials in buildings. Asbestos is safe and legal to remain in homes or public buildings as long as the asbestos materials are in good condition and the asbestos can not be released into the air. Here we provide a master list of manufactured products that contain asbestos. Our list of asbestos-containing materials is sorted by alphabetically by product or use. Contact us by posting a question or comment at the end of this page if you cannot find information you need.
JP5194297B2 - Asbestos modification method - Google Patents
Descubra todo lo que Scribd tiene para ofrecer, incluyendo libros y audiolibros de importantes editoriales. Asbestos - Wikipedia, the free encyclop…. From Wikipedia, the free encyclopedia.
All are composed of long and thin fibrous crystals , each fiber being composed of many microscopic 'fibrils' that can be released into the atmosphere by abrasion and other processes. Asbestos is an excellent electrical insulator and is highly resistant to heat, so for many years it was used as a building material. Inhalation of asbestos fibres can lead to various serious lung conditions, including asbestosis and cancer. Archaeological studies have found evidence of asbestos being used as far back as the Stone Age to strengthen ceramic pots,  but large-scale mining began at the end of the 19th century when manufacturers and builders began using asbestos for its desirable physical properties.
This invention relates to a packaging material for a photographic photosensitive material which improves photographic properties with keeping good dimensional stability, physical strength, moldability and so on. Packaging materials for photographic photosensitive material are required to have good properties about dimensional stability, physical strength, moldability and so on, as well as not to affect photographic properties adversely. A molded article for a photographic photosensitive material disclosed in Japanese Patent KOKAI is made of a resin composition comprising 50 to A thermoplastic resin packaging material for a photographic photosensitive material disclosed in Japanese Patent KOKAl improves photographic properties by descending melting point by using a polymer material having a low molecular weight polymer content of 3 wt.
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