Coal tar-based

For low slope commercial roofing, bituminous-based roof coverings are the most common systems in the United States. Asphalt-based materials predominate over coal-tar based materials in these systems. For residential roofing materials, various types of roofing products, including asphalt, wood, and tile, ate used for both new constmction and reroofing. 

Coal-Tar Pitch Coke. Coal-tar pitch is used to produce needle coke primarily in Japan. Processes for producing needle coke from pitch have also been developed in Germany (4). The key to producing needle coke from coal tar or coal-tar pitch is the removal of the high concentrations of infusible sohds, or material insoluble in quinoline (QI), which are present in the original tar. The QI inhibits the growth of mesophase and results in an isotropic, high CTE coke from coal-tar pitch. After removal of the QI, very anisotropic and low CTE cokes are obtained from coal-tar-based materials. 

The mesophase pitches used for high-modulus carbon fiber production can be formed either by the thermal polymerization of petroleum- or coal tar-based... 

Currently, nearly all domestic pitches are obtained from either coal tar or petroleum precursors [5] The pitch products, whether petroleum-based or coal-tar based, arc prized by the ancillary industnes that are dependent upon them but such pilches arc, nevertheless, considered to be derived from byproduct materials. In addition, besides being derived from byproducts, the yield of pitch typically amounts to no more than 5 wt% based on the initial quantity of coal or crude feedstock [6]. 

A further source of C9 material is coal tar. Structures of the two resins precursors are roughly similar, except the presence of small quantities of coumarone in coal tar feedstream. There is a significant difference in the concentrations of individual monomers coal-tar-based raw material is richer in indene (styrene/indene ratio =1 7) than the petroleum-based feedstream (styrene/indene ratio =1 1). 

Rolling rig machines The rolling rig machine rotates the cleaned and primed pipe on mechanically driven dollies , while a tank travelling alongside the pipe floods it with hot asphalt or coal-tar-base enamel. 

It is often claimed that a coal-tar-base coating absorbs less water than an asphalt coating and there is evidence in practice to support this claim, but some asphalt enamels in practice have been as good as the best coal-tar enamels. 

The field performance of the asphalt-base pipeline enamels was, at one time, erratic, probably because the material had been drawn from varying sources, without a close specification being used. The plasticised coal-tar-base enamel to the American Water Works Association Specification C-203 thus gained some favour in major pipelining organisations. 

N— compounds used as acid inhibitors include heterocyclic bases, such as pyridine, quinoline and various amines. Carassiti describes the inhibitive action of decylamine and quinoline, as well as phenylthiourea and dibenzyl-sulphoxides for the protection of stainless steels in hydrochloric acid pickling. Hudson e/a/. refer to coal tar base fractions for inhibition in sulphuric and hydrochloric acid solutions. Good results are reported with 0-25 vol. Vo of distilled quinoline bases with addition of 0 05m sodium chloride in 4n sulphuric acid at 93°C. The sodium chloride is acting synergistically, e.g. 0-05m NaCl raises the percentage inhibition given by 0-1% quinoline in 2n H2SO4 from 43 to 79%. Similarly, potassium iodide improves the action of phenylthiourea . 

This serendipitous discovery marked the beginning of the synthetic dyestuffs industry, based on coal tar as its main raw material, which is, incidentally, a waste product from another industry, steel manufacture. The development of mauveine was followed by efficient syntheses of natural dyes such as alizarin in 1869 (Graebe and Liebermann, 1869), and indigo in 1878 (Bayer, 1878 Heumann, 1890). The synthetic production of these dyes marked the demise of the agricultural production of these materials and the advent of a science-based, predominantly German chemical industry. The present-day fine chemicals and specialties, e.g. pharmaceuticals, industries developed largely as spin-offs of this coal tar-based dyestuffs industry. 

Acenaphthene occurs naturally in coal tar. Based on laboratory analysis of 7 coal tar samples, acenaphthene concentrations ranged from 350 to 12,000 ppm (EPRl, 1990). Detected in Dyr aged coal tar film and bulk coal tar at concentrations of 5,800 and 5,900 mg/kg, respectively (Nelson et al, 1996). A high-temperature coal tar contained acenaphthene at an average concentration of 1.05 wt % (McNeil, 1983). Lee et al. (1992a) equilibrated 8 coal tars with distilled water at 25 °C. The maximum concentration of acenaphthene observed in the aqueous phase was 0.3 mg/L. 

At temperatures above the softening point, isotropic pitch often displays Newtonian flow characteristics (18,19), but this may well depend upon the concentration of any insoluble particles (i.e., primary QI in the case of coal tar based materials) present within the pitch. A high concentration of QI could lead to non-Newtonian character as a result of the particle-particle attractive forces. Figure 3 shows n -T curves for a variety of pitch materials and their pyrolysis products. Pyrolysis increases the Tg of the system and shifts the viscosity-temperature curve to higher temperatures. 

Organic synthesis followed a different line of evolution. A landmark was Perkin s serendipitous synthesis of mauveine (aniline purple) in 1856 [26] which marked the advent of the synthetic dyestuffs industry, based on coal tar as the raw material. The present day fine chemicals and pharmaceutical industries evolved largely as spin-offs of this activity. Coincidentally, Perkin was trying to synthesise the anti-malarial drug, quinine, by oxidation of a coal tar-based raw material, allyl toluidine, using stoichiometric amounts of potassium dichromate. Fine chemicals and pharmaceuticals have remained primarily the domain of... 

France and Nippon Steel Chemical Co. of Japan have been also producing some coal tar-based cresols. 

It is learnt that even PMC inc., USA, the only virgin cresols manufacturer in USA, has decided to close down its cresol plant and sell out the facilities to interested buyers. Some other coal tar-based units and a few companies recovering cresols from petroleum waste liquors are also closed down. The message is very clear. Government regulations in most of the countries will not permit operations of those units which create pollution and upset the ecosystems. 

Merck had its beginnings in the United States in 1887 as the American marketing branch of one of the leading German producers of fine chemicals. In 1903 this subsidiary introduced the production in Rahway, New Jersey of narcotics, bismuth salts, iodine, and other fine chemicals for the American pharmaceutical industry. During World War I the company turned to the production of coal-tar-based synthetic intermediates, which it had previ-... 

Sixteen urine samples were collected from 4 male, nonsmoking psoriatic patients, undergoing treatment with the Goeckerman regimen (cutaneous application of coal tar based ointment, followed by exposure to UV irradiation) in the Dermatology Clinic of the University of Padua (Clonfero et al. 1989). Patient A was treated with pure coal tar for 1 day patients B, C, and D were treated with 4% coal tar based ointment for 2, 8, and 13 days, respectively. Body surface involved by psoriasis was 30, 40, 35, and 60% for patients A, B, C, and D, respectively. Total PAH (and pyrene) content of the two coal tar preparations was 28,800 (3,100) and 470 (104) ppm, respectively. The samples were collected at different times after the beginning of therapy (from 12 hours after the 1st application of coal tar to 72 hours after the last... 

Previously, the only information on biological indicators of exposure to coal tar found in the available literature involved a study of 1-hydroxypyrene in the urine of a creosote wood-treatment plant worker (Jongeneelen et al. 1985). The pyrene metabolite, 1 -hydroxypyrcnc, is now more commonly used as a biological indicator to assess total PAH exposure in several industries as well as for nonoccupational uses of coal-tar based products (Malkin et al. 1996 Strickland et al. 1996). Elovaara et al. (1995) studied inhalation and dermal exposure to naphthalene and 10 large PAHs in creosote impregnation plant workers. Air concentrations of the compounds were measured and compared with measurements of... 

Coal tar creosote is widely used for the preservation and water-proofing of wood which is used for utility poles, railroad ties, log homes, fence posts, bams, bridges, piers, and marine pilings. Creosote is also used in roofing and road paving is used and/or produced in coke oven operations, and in the aluminum, iron, and steel industries and is used therapeutically in coal-tar based shampoos, as a treatment for... 

Wright CW, Later DW, Pelroy RA, et al. 1985. Comparative chemical and biological analysis of coal-tar based therapeutic agents to other coal-derived materials. J Appl Toxicol 5(2) 80-89. 

Low chlorinated naphthalenes as well as selected PAHs are known as ingredients in coal tar based wood preservation agents (Pommer, 2001 Jacobsson and Asplund, 2000). Thus, we conclude that the occurrence of the described contaminants results from impregnation activities at the former military base. 

A second study characterizing a huge groundwater contamination caused by chemicals used for wood impregnation revealed mono- and dichlorinated naphthalenes, chlorobenzo(b)thiophene, acenaphthene and methylated naphthalenes as the main pollutants. Anaerobic microbial degradation of the main pollutant 1-chloronaphthalene was evident from identification of 1 -chloro-4-naphthol and 1-chloronaphthoic acid as biotic transformation products. In contrast inorganic and compound specific stable carbon isotope analyses indicated only a minor degree of microbial transformation. Thus, sorption seemed to be the main attenuation process within the aquifer affected by the coal tar based contamination described above. 

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