Asphaltic materials

Road oils are Hquid asphalt materials iatended for easy appHcation to earth roads. They provide a strong base or a hard surface and maintain a satisfactory passage for light traffic. Liquid road oils, cutbacks, and emulsions are of recent date, but the use of asphaltic soHds for paving goes back to the European practices of the early 1800s. 

Temperature—Volume Correetion (ASTMD1250). Tables are provided to allow the conversion of volumes of asphaltic materials from one temperature to another or, as generally used, to adjust volumes to a temperature of 15.6 °C, the standard basis of measurement in the United States. 

Liquid propane is a selective hydrocarbon solvent used to separate paraffinic constituents in lube oil base stocks from harmful asphaltic materials. It is also a refrigerant for liquefying natural gas and used for the recovery of condensable hydrocarbons from natural gas. 

On the other hand, liquid propane also has a high affinity for paraffinic hydrocarbons. Propane deasphalting removes asphaltic materials from heavy lube oil base stocks. These materials reduce the viscosity index of lube oils. In this process, liquid propane dissolves mainly paraffinic hydrocarbons and leaves out asphaltic materials. Higher extraction temperatures favor better separation of the asphaltic components. Deasphalted oil is stripped to recover propane, which is recycled. 

An additive described as reducing the water loss and enhancing other properties of well-treating fluids in high-temperature subterranean environments consists of polymers or copolymers from N-vinyl lactam monomers or vinyl-containing sulfonate monomers. Organic compounds like lignites, tannins, and asphaltic materials are added as dispersants [175]. 

This is a batch-type process in which the rates of flow of the solvent, the asphaltic material, the sulfonating agent, and the neutralizing agent and the... 

Peaks observed at 5.90 xm and 8.70 xm were thought to reflect oxidative effects on the asphaltic material, while asphaltic sulfoxide and sulfone were tentatively inferred from bands at 9.76, 8.66, and 7.72 xm. The 12.34/13.88, 12.34/7.27, and 6.25/13.88 xm ratios tended to show the greatest difference between different samples. When the ratio 12.34/7.27 xm versus 12.34/13.88 ixmwere plotted graphically, the intermediate fuel oils behaved similarly [53]. Weathering caused fuel oils to fall below the curve although with asphalts the effect was... 

Commercial alloys, 73 525-530 Commercial asphalt materials, recycling, 23 592... 

The composition of crude oil may vary with the location and age of an oil field, and may even be depth dependent within an individual well or reservoir. Crudes are commonly classified according to their respective distillation residue, which reflects the relative contents of three basic hydrocarbon structural types paraffins, naphthenes, and aromatics. About 85% of all crude oils can be classified as either asphalt based, paraffin based, or mixed based. Asphalt-based crudes contain little paraffin wax and an asphaltic residue (predominantly condensed aromatics). Sulfur, oxygen, and nitrogen contents are often relatively higher in asphalt-based crude in comparison with paraffin-based crudes, which contain little to no asphaltic materials. Mixed-based crude contains considerable amounts of both wax and asphalt. Representative crude oils and their respective composition in respect to paraffins, naphthenes, and aromatics are shown in Figure 4.1. 

For example, treating petroleum distillates with sulfuric acid is generally applied to dissolve unstable or colored substances and sulfur compounds as well as to precipitate asphaltic materials. When drastic conditions are employed, as in the treatment of lubricating fractions with large amounts of concentrated acid or when fuming acid is used in the manufacture of white oils, considerable quantities of petroleum sulfonic acids are formed ... 

The very volatile gases (compounds with four or fewer carbons), crude oil, and the sohd asphaltic materials are not included in this discussion of analytical methods but are included elsewhere (Chapters 7 and 9). 

Airport Cracks Filled with Sulphur-Asphalt Materials",... 

The worldwide disruptions in crude oil supply in 1973-74, 1978-79 and 1980 have illustrated the tenuous nature of imported crude oil supplies. The United States annually consumes approximately 30 million tons (2.7 X 10 kg) of asphalt cement refined from crude oil 93 percent of the total mileage of surfaced highways and streets, or close to 1.6 million miles (2.6 million km), has been constructed with asphalt materials. Thus, the highway industry is very vulnerable to asphalt price and supply problems if crude oil imports again suffer severe disruptions. 

In order to increase the yields of good quality, high viscosity lubricating oils which were in demand at that time, the industry was faced with the problem of developing more efficient methods for separating the oil from the asphaltic materials in the residue. In many cases the residue represented a substantial proportion of the crude oil. Investigations undertaken included chemical treatment with sulfuric acid (35), removal of the asphaltic materials with metallic chlorides (50, 66), and adsorption on clay (56). Solvent precipitation of the asphalts also was studied (11,18, 19, 38, 78). 

The selection of sulfuric acid for removal of asphaltic materials from residual stocks was logically the first choice, because many refiners had used this acid for treating lubricating oil distillates to improve quality. This method of deasphalting was adopted early. 

Asphaltic materials may be separated from the residue by adsorption on clay. The oil is percolated through a relatively tall column of comparatively coarse clay or mixed with a selected clay of fine mesh at relatively high temperatures, and the spent clay is removed by filtration. 

Obviously to remove large amounts of asphaltic materials, substantial quantities of clay would be required in both the percolation and hot contacting methods, and the adsorption process then may become uneconomical in the treating of raw residua. With the exception of residual oils containing low concentrations of asphalts, oils to be treated with clay generally receive some pretreatment—for example, with sulfuric acid followed by neutralization of the acid oil, or selective solvent extraction. 

Metallic chlorides are effective in removing asphaltic materials, and one plant was installed about 1934 for treatment of lubricating oils by the Alchlor process using aluminum chloride (51). It is reported that after such treatment, residual oils are free from resinous and asphaltic materials. Although aluminum chloride treating of lubricating oils is in commercial operation, the process apparently has not been extended beyond the one installation. 

Early investigations dealing with solvents showed that alcohols, alcohol-ether mixtures, ketones, and petroleum naphthas were effective to some extent in removing asphaltic materials from petroleum fractions. The alcohols appeared to be the most promising, but at the relatively low temperatures required (about 35° F.) the viscosity of the alcohol-... 

With the introduction of dist.illa.tion and fractionation under high vacuum in the presence of steam, it was possible to effect a relatively efficient separation of oil from the asphalts. However, in the case of the more highly paraffinic crudes, a complete separation between oil and asphaltic materials could not be made, because the high viscosity oil fractions which have very low vapor pressures are thermally decomposed at the relatively high temperatures required in the distillation. 

The development of modern fractionating equipment, in which a minimum pressure drop exists across the bubble trays, brought about a further improvement in the efficiency of the separation of oils from the asphaltic materials. Modern vacuum distillation is widely used at the present time for the production of oils of low asphaltic material content. 

The most outstanding development resulting from these investigations is the use of liquid propane for the selective precipitation of resins and asphalts. The development of the propane deasphalting process is a very important contribution to petroleum technology in the refining of residual oils and provides a method for substantially complete separation of lubricating oils from the asphaltic materials contained in the residua derived from any crude source. 

Propane is a unique solvent, in that its solvent power for oil is reversed over the range of about 110° to 200° F., exhibiting less solvent power as the temperature is increased. This is in contrast to the action of ordinary selective solvents, which exhibit increased oil solvent power as the temperature is raised. By taking advantage of this property of propane and by controlling the temperature and propane ratio, very efficient separation of the asphaltic materials can be attained. 

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