Petroleum asphalt from

Asphalt (qv) is prepared from petroleum and often resembles bitumen. When asphalt is produced simply by distillation of an asphaltic cmde, the product can be referred to as residual asphalt or straight-mn petroleum asphalt. If the asphalt is prepared by solvent extraction of residua or by light hydrocarbon (propane) precipitation, or if blown or otherwise treated, the term should be modified accordingly to qualify the product, eg, propane asphalt. 

ASTM (1) further classifies asphalts or bituminous materials as soHds, semisoUds, or Hquids. SemisoHd and Hquid asphalts predominate in commercial practice today. Prior to 1907, the principal portion of asphalt used occurred naturally since that time most asphalts have been produced from the refining of petroleum. Air-blown petroleum asphalts (5) of diverse hardness became available in the early 1900s, and as thek use increased, the demand for native products diminished. 

Petroleum asphalts, compared to native asphalts, are organic with only trace amounts of inorganic materials. They derive their characteristics from the nature of their cmde origins with some variation possible by choice of manufacturing process. Although there are a number of refineries or refinery units whose prime function is to produce asphalt, petroleum asphalt is primarily a product of integrated refineries (Fig. 1). Cmdes may be selected for these refineries for a variety of other product requirements and the asphalt (or residuum) produced may vary somewhat in characteristics from one refinery-cmde system to another and even by cut-point (Table 2) and asphalt content (Fig. 2) (5,6). The approximate asphalt yields (%) from various cmde oils are as follows ... 

Propane Asphalt. As noted above, cmde oils contain different quantities of residuum (Fig. 2) and, hence, asphalt. Asphalt is also a product of the propane deasphalting and fractionation process (5,6,21,22) which involves the precipitation of asphalt from a residuum stock by treatment with propane under controlled conditions. The petroleum charge stock is usually atmospheric-reduced residue from a primary distillation tower. 

Test Procedures. Most tests apphed to petroleum asphalts are empirical in nature (45). The ASTM tests are not the only ones appHed to asphalt testing. Private tests of a propriety nature have been used within companies. Some of these tests are now being made pubHc and occur from time to time in Hterature reports. Such tests may become a part of the ASTM standards. 

In pipelining, the trend is towards all-welded steel for long lines, and since the wall thickness is less than that of cast iron, protection is the more important. Many types of coating are used, from thick concrete to thin paint films, and each has its own particular suitability, but the majority of pipelines throughout the world today are coated with hot-applied coal tar or petroleum asphalt-base-filled pipeline enamels, into which reinforcing wraps, such as glass fibre are applied. 

Uses/Sources. Asphalt fumes arise from asphalt used for road construction, roofing, and coating of construction materials and in association with the production of asphalt from petroleum in asphalt-based paints... 

Blown, or oxidized, petroleum asphalts were first produced commercially by Byerley about 1894. But neither blown nor residual asphalts from the early crudes enjoyed very good repute in the United States, partly because of the nature of the crudes and partly because of insufficient care in manufacture. Discovery of sources of asphaltic and semi-asphaltic crudes made possible the production of residual petroleum asphalts suitable for paving, and improvements in the blowing process led to products well suited for the manufacture of prepared roofings. In fact, the early growth of the roofing industry corresponded closely with the production of petroleum asphalts (86). 

BITUMEN. Natural flammable substances of a wide range of color, hardness, and volatility, constituted mainly of a mixture of hydrocarbons and essentially free from oxygenated bodies. Petroleums, asphalts, natural mineral waxes, and asphaltites arc considered bitumens. See also Tar Sands. 

Deasphalting—Process for removing asphalt from petroleum fractions, such as reduced crude. A common deasphalting process introduces liquid propane, in which the nonasphaltic compounds are soluble while the asphalt settles out. 

U ecently, interest in sulfur utilization in asphalt paving materials has been rekindled. One of the foremost reasons for this is the potential availability of surplus sulfur recovered from secondary sources in connection with meeting environmental pollution standards (I). These sources include sulfur recovered from sour gas, from refining of petroleum, and from smelter and powerplant stack gases. Another potential saving of energy and petroleum is possible by replacing part of the asphalt binder with sulfur (2). 

Petroleum asphalts can be manufactured from various crudes using different processes. Asphalt, being the highest boiling fraction of petroleum, can be manufactured by vacuum distillation of crude oil or by treatment of petroleum residue with propane under controlled conditions. Asphalt can also be a product of an air-blowing process in which petroleum residue is contacted with air at temperatures ranging from 200° to 280° C. 

Samples. Two straight-reduced asphalts from Romashkino-type (29° API gravity) crude petroleum, 100 penetration (SR-100) and 125 penetration (SR-125), and three air-blown asphalts of different degrees of oxidation, 100, 50, and 25 penetration (AB-100, AB-50, and AB-25) were investigated. The air-blown asphalts were derived from SR-125. The properties of the asphalts are given in Table I. 

Descriptions are provided for (1) desalting and dewatering (2) separation processes, of which distillation is the prime example (3) conversion processes, of which coking and catalytic cracking are prime examples and (4) finishing processes, of which hydrotreating to remove sulfur is a prime example. Descriptions of the various petroleum products (from fuel gas to asphalt and coke) sire also given. 

A petroleum seep is defined as visible evidence at the Earth s surface of the present or past leakage of oil, gas, or bitumen from the subsurface. Seeps have been utilized at least since ancient tribes of the Near East recovered blocks of asphalt from the Dead Sea. Many studies have demonstrated the worldwide correlation between seeps and earthquakes, with most visible seeps being near past or present areas of tectonic activity. The presence of seeps in a basin can considerably reduce the exploration risk because these seeps indicate that petroleum-forming processes have been active in the subsurface. In a situation where the major pathway for seeps is along a fault, the intensity and shape of the seep are significantly different from those situations where vertical leakage has occurred, and this difference permits their distinction. 

Chrysene occurs as a product of combustion of fossil fuels and has been detected in automobile exhaust. Chrysene has also been detected in air samples collected from a variety of regions nationally and internationally. The concentrations were dependent on proximity to nearby sources of pollution such as traffic highways and industries, and was also dependent on seasons (generally higher concentrations were noted in winter months). Chrysene has also been detected in cigarette smoke and in other kinds of soot and smoke samples (carbon black soot, wood smoke, and soot from premixed acetylene oxygen flames). It has been detected as a component in petroleum products including clarified oil, solvents, waxes, tar oil, petrolatum, creosote, coal tar, cracked petroleum residue, extracts of bituminous coal, extracts from shale, petroleum asphalts, and coal tar pitch. 

The products obtained by vacuum distillation include fuel oils and asphalts. From them the refiner extracts lubricating oils, petroleum and paraffin. 

The Syriac asphalt (from the Dead Sea) forms deep black, shining, brittle masses of conchoidal fracture faint pitch-like odor and luster. Burns with a bright flame, d 1.00-1.18. fnsol in water, ale, adds, alkalies so] in oil turpentine, petroleum, CS2 chloroform, ether, acetone. 

EXPOSURE ROUTES inhalation ingestion cigarette smoke condensate automobile exhaust soot emissions from coal and gas works and electric plants aromatic fraction of mineral oil commercial solvents, waxes, petrolatum, creosote, coal tar, petroleum asphalt, coal tar pitch charcoal broiled barbecued, or smoke meats and fish certain vegetables and vegetable oils coffee... 

While it is conceded that synthetic bitumen obtained from the hydrogenation of coal is not the same as a petroleum asphalt, still there are similarities that may permit characterization in similar terms. The same element of immiscibility exists between oils and asphaltene constituents or tars (oxygenated materials). It has been noted that these raw synthetic bitumen contain volatile oils and hard, asphaltene-like constituents. The oils are predominantly aromatic, giving stable sol-like dispersions with high temperature susceptibility and exhibiting Newtonian behavior. 

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