|Publication number||US3360455 A|
|Publication date||Dec 26, 1967|
|Filing date||Jan 27, 1966|
|Priority date||Jan 27, 1966|
|Publication number||US 3360455 A, US 3360455A, US-A-3360455, US3360455 A, US3360455A|
|Inventors||Corbett Luke W, Swarbrick Robert E|
|Original Assignee||Exxon Research Engineering Co|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (7), Referenced by (9), Classifications (10)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Dec. 26, 1967 "w CORBETT ET AL 3,360,455
' SPHALT PLASTISQLS Filed Jan. 27, 1966' DISTILL ATlON ASPHAlI FEED n-HEPTANE 7 n-HEPTANE .STORAGE TO STORAGE i FLASH TOWER ll MIXING 'HEAD I coouwe VESSEL 25 v .20 Y CENTRlFUG E l 27 2s- A H 12' n-HEPTANE 17 TO STORAGE I/ZB l3 4 1 i V/ I5 PULVERIZER FLASH TOWER MIXING VESSEL MIXING vE ssEL ASPHALT PLASTlSOL 32 A LUKE W. CORBETT ROBERT E. SWARBRICKI INVENTORS PATENT ATTORNEY United States Patent 3,360,455 ASPHALT PLASTISOLS Luke W. Corbett, Mountainside, and Robert E. Swarbrick,
Belle Mead, N.J., assignors to Esso Research and Engineering Company, a corporation of Delaware Filed Jan. 27, 1966, Ser. No. 523,299 5 Claims. (Cl. 20822) ABSTRACT OF THE DISCLOSURE Asphalts are fractionated into asphaltenes, high molecular weight petrolenes and low molecular weight petrolenes. The high molecular weight petrolene fraction is coated with the asphaltene fraction and thereafter suspended in the low molecular weight petrolene fraction to form a stable asphalt plastisol.
This invention relates to asphalt compositions having improved flow properties and more particularly to stable asphalt plastisols and their preparation.
The general method used in preparing hot-mix pavements is by preheating mineral aggregate to approximately 325 F. and coating this aggregate with asphalt ranging in softening point from about 105 F. up to about 140 F. This asphalt is also preheated to approximately 300 P. so that it will effectively spread over the mineral particle surfaces. The practical difiiculties encountered with this general method are the large amounts of heat that must be employed in order to fluidize the asphalt binder and the inherent problems encountered in storing and transferring the asphalt in this fluid condition.
Thus, it is a primary object of this invention to provide useful asphalt compositions which are fluid and of low viscosity at ordinary ambient temperatures and which can be easily stored, transferred and mixed without the application of large amounts of heat.
The present invention is predicated on the discovery that asphalt can be separated into several fractions which can subsequently be recombined in a particular manner to form a stable asphalt plastisol having substantially improved ilow properties and which can be used in the same application as the original asphalt composition. As is well known in the art, asphalt can be regarded as comprising two general components, i.e., petrolenes and asphaltenes. The asphaltenes are distinguished from the petrolenes in that asphaltenes have a much higher molecular weight, a higher boiling point and are higher in aromaticity. Both materials are themselves mixtures of hydrocarbons and their heteroatom analogs.
In accordance with this invention, asphalt compositions are rendered fluid by a process comprising the necessary steps of: (l) admixing asphaltenes and nonvolatile petrolene particles having an initial atmospheric boiling point within the range between about 600 F. and 1400 F. to form asphaltene-coated nonvolatile petrolene particles and (2) admixing the said coated particles with liquid volatile petrolenes to produce an asphalt plastisol.
When starting with atypical asphalt feed, an embodiment of this invention comprises (1) distilling the asphalt at elevated temperatures and reduced pressures to separate the lower boiling fractions, i.e., the volatile petrolenes, from the nonvolatile fraction comprised of asphaltenes and nonvolatile petrolenes and having an initial boiling point within the range between 600 and 1400 F., (2) contacting the nonvolatile fraction with a liquid parafiin to precipitate the asphaltenes and form an asphaltene fraction and a nonvolatile petrolene fraction, (3) separating said asphaltene fraction from said nonvolatile petrolene fraction, (4) removing said liquid ice parafiin from said asphaltene fraction and said nonvolatile petrolene fraction, (5) cooling the said nonvolatile petrolene fraction, (6) pulverizing the said cooled nonvolatile petrolene fraction, (7) admixing the said asphaltenes and said pulverized nonvolatile petrolenes to form asphaltene-coated nonvolatile petrolene particles and (8) admixing the said coated particles with the said volatile petrolenes to produce an asphalt plastisol.
The invention will be more fully understood by referring to FIGURE 1 which shows a flow diagram of one embodiment of the same.
While the process of the present invention may be employed to fiuidize asphalts, residua, heavy fuel oils and the like, it has special application to asphalts. The present invention contemplates the employment of any asphalt composition comprising petrolenes and asphaltenes. The asphalt composition is not critical because no modification of the composition is produced by the practice of the present invention but rather what is accomplished is the physical modification of the asphalt in such a manner that its flow properties are vastly improved. Illustrative of this is the fact that a solid asphalt paving binder can be processed according to the present invention to yield a fluid, low viscosity asphalt paving binder which can subsequently be added to the hot mineral aggregate to produce an asphalt pavement having the same properties as would be obtained by the use of the hot mineral aggregate with the norm-ally solid asphalt paving binder. Broadly, the asphalts which are operable in the concept of this invention may contain from about 20 to about 60 wt. percent volatile petrolenes, from about 10 to about 50 wt. percent nonvolatile petrolenes (i.e., those petrolenes having an initial boiling point within the range between 600 and 1400 F.) and from about 5 to about 40 wt. percent asphaltenes. Nonlimiting examples of asphalts which may be employed are straight reduced asphalts, air blown asphalts and blended asphalts having the foregoing compositions. The asphalts may be, for example, derived from Lagunillas, Boscan, Aramco, Talco, Kuwait, Oregon Basin, Lloydminster, Santa Maria, Kern River, and Eucutta crudes and the like. In addition, the asphalt plastisol may be formulated from the total amount of materials fractionated from the asphalt or it may be formulated from only a portion of the materials fractionated provided, however, that the resultant product composition is within the beforementioned operable range.
The precipitant used to separate asphaltenes from the nonvolatile petrolenes includes any liquid parafiin which, when contacted wtih a petroleum fraction containing asphaltenes, causes said asphaltenes to precipitate as solids. Such precipitants are well known in the art, e.g., US. Patent 3,087,887, which is incorporated herein by reference. Such precipitants include the C to C par-afiins, preferably the saturated C to C normal paraffins. Nonlimiting examples of suitable precipitants are n-pentane, n-hexane, n-hexane, isooctane, dodecane and the like.
The asphalt is fed into a distillation zone where the volatile petrolenes are separated in accordance with known techniques from the nonvolatile fraction comprising nonvolatile petrolenes and asphaltenes. The temperature and pressure employed will depend upon the particular asphalt which is to be fractionated. In general, asphalts having higher boiling points will require lower distillation pressures and/0r higher distillation temperatures. Broadly, the conditions used include a temperature of from about 400 to about 800 F. and a pressure less than atmospheric, i.e., between about .1 and about 50 mm. of mercury absolute. It is preferred, however, that the temperature be less than 750 F. and the pressure be less than 2 mm. Hg. Temperatures in excess of 800 F. should be avoided in order to minimize any possible thermal degradation of the asphalt. The temperature, pressure and time in the distillation zone should be adjusted so that the initial atmospheric boiling point of the nonvolatile fraction (i.e., the distillation bottoms) which is withdrawn will be within the range between about 600 and 1400 F. The boil 'ing point range of the volatile petrolenes (i.e., the distillation overhead) will be, of course, within the range between the initial boiling point of the asphalt feed and the initial boiling point of the aforedescribed nonvolatile fraction.
The nonvolatile fraction recovered from the distillation zone is contacted with the aforedescribed liquid paraffin into which asphaltenes precipitate as solids. The temperatures and pressures used may vary widely. It has been found that this separation can be conveniently effected at a temperature of from about 50 to about 200 F. and at atmospheric pressure. Contact time is not critical since upon contact of the nonvolatile fraction with the liquid paraffin, precipitation of the asphaltenes as solids is very rapid. The precipitated asphaltene fraction is then subsequently removed from the petrolene fraction by filtration or by centrifugation, preferably the latter. The separated asphaltene fraction and the nonvolatile petrolene fraction are then separately treated in order to isolate the respective products. For example, the separated asphaltenes may be dried in air at ambient temperatures or at elevated temperatures (e.g., 150 F.) under inert atmosphere. The separated petrolenes may be conveniently recovered from solution by distilling off the liquid paraifin at a temperature of 100 to 175 F. and a pressure of 25 to 100 mm. Hg absolute.
The nonvolatile petrolenes recovered from the liquid paraffin solution are cooled to temperatures below about 60 F., preferably below about 40 F., and pulverized at this temperature to pass a number 8 US. Standard Sieve screen. Nonvolatile petrolene particles of from about number 200 to about number 8 US. Standard Sieve size have been found to be particularly effective in the concept of this invention.
In accordance with this invention the cooled nonvolatile petrolenes are admixed after pulverizing with asphaltenes until the surface of the nonvolatile petrolene particles are coated with the dust-like asphaltenes. The asphaltenes, being essentially infusible and dust-like, tend to coat or dust the surface of the ground petrolenes. This coating technique is desirable to prevent coalescing of the nonvolatile petrolene particles. The foregoing pulverizing and mixing operations can be effected in any conventional equipment such as a pulverizing mill or a ball mill. The asphaltene-nonvolatile petrolene blend is subsequently admixed at ambient temperatures (e.g.,' 60100 F.) with the volatile petrolenes which being liquid act as a plasticizer and produce an asphalt plastisol, i.e., a dispersion of a finely divided solid in a liquid. Broadly, these asphalt plastisols comprise from about 10 to about 50 wt. percent nonvolatile petrolenes, from about to about 40 Wt. percent asphaltenes and from about 20 to about 60 wt. percent volatile petrolenes. It is preferred, however, that they comprise from about 15 to about 30 wt. percent nonvolatile petrolenes, from about 20 to about 35 wt. percent asphaltenes and from about 35 to about 50 wt. percent volatile petrolenes.
Turning now to the figure, a straight reduced residuum from a Venezuelan crude having an ASTM softening point of 115 R, an ASTM penetration 77 F. of 90; and composed of 84 wt. percent petrolenes and 16 wt. percent asphaltenes is used as the feed in the specific embodiment to be described hereinafter. The feed is heated to 270 F. and pumped through line 1 into distillation vessel 2 which may be a vacuum pipestill. The temperature and pressure employed are approximately 700 F. and 5 mm. Hg absolute respectively. The low boiling material, i.e., the volatile petrolenes, are taken off overhead through line 3 and condensed in condenser 4 at about 180 F. and then pumped through line 5 into mixing vessel 31.
The bottoms from vessel 2, i.e., the nonvolatile fraction comprising asphaltenes and nonvolatile petrolenes and having an initial boiling point of about 1150 F., are withdrawn through line '6 as a liquid at about 500 F., cooled in heat exchanger 7 to about 300 F., and then passed through line 8. Liquid normal heptane from storage 9 111 an amount sufiicient to precipitate the asphaltenes is then pumped via line 10 into contact with the nonvolatile fraction in line 8. The mixture ratio is preferably 12/1 of normal heptane to nonvolatile fraction by volume, although this may vary from about 4/1 to 50/ 1. Other liquid paraffins as hereinbefore mentioned may be used in place of normal heptane. The mixture is then passed through a mixing head 11 or some other suitable mixing device and thence into a continuous type high speed centrifuge 12 wherein the precipitated asphaltenes are separated from the nonvolatile petrolene-hexane solution. The asphaltene-hexane slurry rejected from the centrifuge is then continuously pumped through line 13 into heat exchanger 14 wherein it is heated to about 250 F. and thence to flash tower 16 by means of line 15 for stripping at atmospheric pressure. Normal heptane is taken overhead through line 17, subsequently condensed and sent to storage. The bottoms from flash tower 16, i.e. the asphaltenes, are withdrawn as solids via line 18 and sent to mixing vessel 19. The nonvolatile petrolenes from centrifuge 12 are withdrawn through line 20, heated in heat exchanger 21 to about 250 F. and sent to flash tower 23 via line 22 wherein normal heptane is taken overhead through line 24 for reuse and the nonvolatile petrolene bottoms is withdrawn through line 25. The nonvolatile petrolenes are then cooled to about 20 F. in cooling vessel 26 and then conveyed as solids via line 27 to pulverizer 28 which may be a rod mill or ball mill. The ground nonvolatile petrolenes are then sent by means of line 29 into mixing vessel 19 for admixture with the asphaltenes at a temperature of about 20 F. The solid asphaltenenonvolatile petrolene blend is sent via line 30 into mixing vessel 31 wherein it is combined at 75 F. with the volatile petrolenes to yield an asphalt plastisol comprising 51 wt. percent nonvolatile petrolenes, 16 wt. percent asphaltenes and 33 wt. percent volatile petrolenes.
The invention can more fully be understood by reference to the following examples.
Example 1 An asphalt, i.e., a straight reduced Venezuelan crude Oll residuum, having an ASTM softening point of F. and a viscosity at 77 F. of 6.5 1O poises, was processed according to the process illustrated in the figure. The yield of the fractions separated from the asphalt were based on the total weight of the asphalt fractionated, 44 wt. percent volatile petrolenes, 13 wt. percent asphaltenes and 43 wt. percent nonvolatile petrolenes. These materials were combined in accordance with this inventlon to form an asphalt plastisol having an ASTM softening point of 50 F. This asphalt plastisol was then combmed with a mineral aggregate commonly used in paving, i.e., an Asphalt Institute type VIa graded aggregate. This was done by the conventional hot-mix method except that the aggregate was heated to 400 F. and the binder was added cold as a plastisol rather than as a hot asphalt liquid. After mixing for 5 minutes, Marshall briquets were prepared and tested by the Marshall test method The original solid asphalt was also combined with the aforedescribed mineral aggregate by the conventional hotmix process, i.e., both the nonplastisol asphalt and the mineral aggregate were. preheated prior to admixture. This admixture was also tested by the Marshall test method. The comparative test results for test specimens containing 6.5 Wt. percent of the plastisol or nonplastisol and 93.5 wt. percent of the aforedescribed aggregate are shown in Table I. It is seen from the foregoing and Table I that the practice of the present invention results in a substantial improvement in the asphalt fluidity without any TABLE I.MARSHALL TEST Binder Used Nonplastisol Asphalt Asphalt Plastisol Voids, percent 6.0 6. Marshall Stability 140 F., lbs 760 750 Marshall Flow 140 F., .01 10 10 l ASTM D 155962T=Test for Resistance to Plastic Flow of Bituminous Mixtures Using Marshall Apparatus.
Example 2 As hereinbefore mentioned, asphalt plastisols may be formulated from the total amount of materials fractionated from the asphalt, as in Example 1, or they may be formulated from only a portion of the fractions separated. The latter procedure has the advantage that the performance properties can be improved by the proper selection of the amounts of materials to be combined to yield the plastisol. Portions of the separated volatile petrolenes, asphaltenes and nonvolatile petrolenes from Example 1 were combined to formulate a plastisol consisting of 47 /2 wt. percent volatile petrolenes, 38 wt. percent asphaltenes and 14 /2 wt. percent nonvolatile petrolenes. The resultant plastisol had an ASTM softening point of 60 F. and a viscosity at 77 F. of 7.8)(10' poise. A portion of this plastisol was then fluxed at 400 F. to break down the plastisol and to yield a nonplastisol asphalt having the same composition of the plastisol. This nonplastisol asphalt had a softening point of 108 F. and a viscosity at 77 F. of 1.4 1O poise. As in Example 1, Marshall briquets were prepared from both the asphalt plastisol and the solid nonplastisol asphalt. The comparative test results for test specimens containing 6.5 wt. percent of the plastisol or nonplastisol and 93.5 wt. percent of an Asphalt Institute type VI aggregate are shown in Table II. It is again seen that the fluidity of the asphalt has been substantially improved without any detrimental effect on the asphalt performance properties.
TABLE IL-MARSHALL TEST Binder Used Nonplastisol Asphalt Asphalt Plastisol Voids, percent 3. 3. 2 Marshall Stability 140 F., lbs 2, 200 2, 450 Marshall Flow 140 F., .01 9
1 ASTM D 1559-62T.
Example 3 1 from both the' foregoing asphalt plastisol and the nonplastisol asphalt. The test results for test specimens containing 6.5 wt. percent of the plastisol or nonplastisol and 93.5 wt. percent of an Asphalt Institute type VI aggregate are given in Table III and again show that this invention affords a method for substantially improving the fluidity of asphalt without adversely affecting the performance characteristics of the asphalt.
TABLE IIL-MARSHALL TEST l Binder Used Nonplastisol Asphalt Asphalt Plastisol Voids, percent 4. 0 4. 5 Marshall Stability F., lbs...-- 1, 500 1, 425 Marshall Flow 140 F., .01" 11 12 1 ASTM D l559-62T.
It is not intended to restrict the present invention to the foregoing examples but rather it should be only limited by the appended claims.
What is claimed is:
1. An asphalt plastisol comprising nonvolatile petrolene particles, having an initial atmospheric boiling point within the range of 600 and 1400 F., passing a number 8 US. Sandard Sieve screen, coated with asphaltenes and suspended in liquid volatile petrolenes having a boiling point range below that of the said nonvolatile petrolenes, said asphalt plastisol being comprised of from about 10 to about 50 wt. percent of said nonvolatile pertolenes, from about 5 to about 40 wt. percent of said asphaltenes and from about 20 to about 60 wt. percent of said liquid volatile petrolenes.
2. An asphalt plastisol according to claim 1 wherein the said asphalt plastisol comprises from about 15 to about 30 wt. percent of said nonvolatile petrolenes, from about 20 to about 35 wt. percent of said asphaltenes and from about 35 to 50 wt. percent of said liquid volatile petrolenes.
3. A process for the manufacture of asphalt plastisols which comprises admixing asphaltenes and nonvolatile petrolene particles having an initial atmospheric boiling point within the range between about 600 F. and 1400 F. to form asphaltene-coated nonvolatile petrolene particles, admixing the said coated particles with liquid volatile petrolenes having a boiling pont range below that of sad nonvolatile petrolenes to produce an asphalt plastisol comprising from about 10 to about 50 wt. percent nonvolatile petrolenes, from about 5 to about 40 wt. percent asphaltenes and from about 20 to about 60 Wt. percent volatile petrolenes.
4. A process according to claim 3 wherein the said nonvolatile petrolene particles have been passed through a number 8 US. Standard Sieve screen.
5. A process for the manufacture of asphalt plastisols which comprises:
( 1) functionating an asphalt comprised of asphaltenes and petrolenes into (a) a volatile petrolene fraction having an atmospheric boiling point below about 600 F. and (b) a nonvolatile fraction comprised of asphaltenes and nonvolatile petrolenes and having an initial atmospheric boiling point Within the range between about 600 and 1400 F.;
(2) contacting the nonvolatile fraction with a C C normal paraffin to precipitate the asphaltenes and form an asphaltene fraction and a nonvolatile petrolene fraction;
(3) separating said asphaltene fraction from said nonvolatile petrolene fraction;
(4) removing the C -C normal parafiin from the asphaltene fraction and the nonvolatile petrolene fraction;
(5) cooling the nonvolatile petrolene fraction to a temperature below about 60 F.;
(6) pulverizing the cooled nonvolatile petrolene fraction;
(7) admixing the asphaltenes and the pulverized nonvolatile petrolenes to form asphaltene-coated nonvolatile petrolene particles; and
(8) admixing the coated particles with the volatile petrolenes produced in step 1) to form a stable asphalt plastisol consisting essentially of from about 10 to about 50 wt. percent of said nonvolatile petrolenes, from about 5 to about 40 wt. percent of said asphaltenes and from about 20 to about 60 wt. percent of said volatile petrolenes.
References Cited UNITED STATES PATENTS 9/1938 Wells et al. 208-44 10/1951 Mollring 208-22 10/1955 Hardrnan 20823 12/1958 Illman 20823 1/1959 Illman 208-23 7/1959 'Hardman et al. 208-22 1/1963 Corbett 20823 DANIEL E. WY MAN, Primary Examiner.
P. E. KONOPKA, Assistant Examiner.
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|U.S. Classification||208/22, 106/280, 208/45, 106/278, 208/23, 106/279, 106/284.1|