US2013619A - Process of producing purified asphalt from soap-containing asphaltic petroleum residuum - Google Patents

Description

Sept. 3, 1935. H F. T T 2,013,619

PROCESS OF PRODUCING PURIFIED ASPHALT FROM SOAP CONTAINING ASPHALTIC PETROLEUM RESIDUUM Filed Sept. 50, 1955 2 Sheets-Sheet l PRESSURE fi'EL/EF lv/ zwsss; A/ar y 674175 2 00 Sept. 3, 1935. ANGSTADT 2,013,619

. PROCESS OF PRODUCING PURIFIED ASPHALT FROM SOAP CONTAINING ASPHALTIC PETROLEUM RESIDUUM Filed Sept. 30, 1955 2 Sheets-Sheet 2 EMULS/FY/NG cu rrwa Arman E a.

Patented Sept. 3, 1935 UITE PROCESS OF PRODUCING PURIFIED AS- PHALT FROM SOAP-CONTAINING AS- PHALTEC PETROLEUM RESIDUUM of New Jersey Application September 30, 1933, Serial No. 691,630

11 Claims.

In the distillation of lubricating oils from crude oil in accordance with Pew Patent 1,761,153, dated June 3, 1930, and in accordance with other processes wherein an addition of sodium hydroxide, or similarly acting alkali, is made to a crude or to a topped crude, there is produced an asphaltic residuum containing soaps of petroleum fatty acids.

The petroleum residuum produced by the process described in the Pew patent above noted has the following physical characteristics, depending on the type of crude processed and the amount of oil remaining undistilled in the bottoms:

Gravity at 60 F 8-15 A. P. I. Flash-Cleveland open cup 400 F. Fire-Cleveland open cup 600 F. Saybolt Vis. at 210 F NW-5000 This asphaltic residuum, due to the fact that it contains approximately '7 to 14% petroleum acid soaps of high molecular weight, is not usable, as it comes from the still, for many commercial purposes, nor is it made usable by oxidizing it by the usual blowing with air or steam. Due to the presence of these soaps, the residuum is miscible, when slightly heated, in substantially all proportions with water, forming therewith an emulsion which remains stable on cooling. In my application, Serial No. 493,242, filed November 3, 1930, which has matured into Patent 1,931,880, Oct. 24, 1933, I describe a process for extracting these soaps from the asphaltic bottoms. The process described, however, is not a continuous one and is therefore not practical where large quantities of this asphaltic residuum must be treated in order to remove the soap content. 7

An object of the present invention is to continuously produce a non-emulsifying asphalt from a petroleum residuum containing soaps formed by distillation in the presence of an alkali.

Another object of the invention is to produce a petroleum fatty acid from crude soaps extracted from the asphaltic residuum.

Another object of the invention is to convert such purified petroleum acid into an emulsifying oil for use as a cutting oil, insecticide and for many other purposes wherein a readily emulsifiable mineral oil is required.

Still another object of the invention is to provide an emulsifiab-le road oil by proper combination of a substantially dehydrated non-emulsifying asphalt and a petroleum fatty acid soap.

These objects are attained in my improved process. The process is not dependent for its execution upon any particular apparatus, but the one shown in the drawings, which I shall describe in detail, is particularly adapted to an efficient execution of the process.

Figs. 1A and 1B are diagrammatic views showing different parts of the entire apparatus, Fig.

1A showing that part of the apparatus in which acid soaps are extracted from the petroleum residue, and Fig. 1B that part of the apparatus in which the crude acid soaps are pumped and treated to produce finished products therefrom.

In the drawings, l designates a line for feeding the asphaltic residuum from the source of supply to heat exchangers w and b. c designates a mixing chamber for thoroughly mixing the residuum fed through line I with water, fed through line 2, which has been previously heated in exchanger d, as will be hereinafter more fully described. 3 designates a line leading from the mixing chamber through heat exchanger e and back to one end of heat exchanger (1.. Heat exchanger a is connected at the other end through line 6 with a steam heater f and a pressure separator g. The top of pressure separator g is connected by line 5 with an asphalt dehydrator h and at the bottom, through line 6, with heat exchanger e, which in turn, through line I, is connected to heat exchanger (1. Heat exchanger it also communicates through line 9 and branches therefrom with storage tanks 8.

Each of tanks 8 communicates with line l leading to an agitator 7c of a type ordinarily used in oil treating. From the bottom of agitator is material may be drawn off through line I I having branches l2 and 13 therein, branch line 52 leading to any suitable drain connection, and branch line !3 to a storage tank It. This storage tank M is connected by line l with a vacuum distillation unit p which may be of any suitable type. From the vacuum still p a line 56 leads to a storage tank ll and a line 18 leads to a storage tank i9. Storage tank 59 communicates through line 20 with an agitator m, the bottom of which communicates with a storage tank 2! through line 22.

Agitator 7c is provided with an inlet pipe 23 for feeding sulphuric or other suitable acid contained in tank 24 and with line 25 for feeding refined mineral oil contained in tank 26. Agitator 7c is also provided with an inlet 21 for water and is internally heated by means of a steam coil 28. Steam coil 28 is, of course, provided with suitable inlet and outlet pipes. In order to insure complete agitation, there is provided a nozzle or rosette in the lower portion of the agitator connected with an air line 29.

Agitator m is provided with a heating coil 30 and air agitating means fed by line 3 I. There are also provided lines 32 and s3 communicating respectively with tanks 34 and 35 for storing sodium hydroxide solution and refined mineral oil, respectively to be fed to the agitator.

In operation, petroleum residuum is fed to the apparatus through line I. This asphaltic residuum, which is the bottoms from a process such as that of the above mentioned Pew patent, is

usually at a temperature from 600 to 650 F., the temperature depending on the type of crude or mixture of crudes which is being distilled and the amount of lubricants removed therefrom. This residuum at the temperature mentioned is much too hot for immediate admixture withwater, which is necessary to the present process, as such high temperatures would necessitate maintaining the mixture under extremely high pressure. Therefore, the residuum is cooled to about 200 F., and mixed with water at the same temperature, and at a pressure, but slightly above atmospheric, that will not effect the formation of steam. To effect an initial cooling preparatory to admixing the residuum with water, it is passed through heat exchanger a, wherein it is cooled to a temperature approximating 380 F. by passing in exchange with residuum which has been already mixed with water, and which is being heated for passage to the separator. In order to cool the residuum still further before admixture with water, it is passed through exchanger b, wherein it is cooled to 200 F. by indirect heat exchange with water. After leaving the ex changer b the mixture is passed into the mixing chamber 0. Just prior to its passage into the mixing chamber, the residuum is mixed with water entering through line 2, at substantially the same temperature. This water, as shown in the drawings, is heated in heat exchanger (1 by heat exchange with crude soap solution which has been separated from the asphalt-water emulsion. Sufficient pressure is imposed on line 2 to at least equal the pressure of the residuum passing into the mixer through line I. Such pressure is imposed by the pump shown in the drawings. While in the mixer c the residuum and water are thoroughly mixed and form an emulsion which is stable at low temperature and atmospheric pressure. This emulsion is withdrawn through line 3 by means of the pump shown and is passed through heat exchangers e and a, line 4 and heat exchanger 1 to the separator g. In passing through heat exchanger e the mixture is heated to a temperature approximating 265 F. by heat interchange with the separated soap solution passing from the bottom of the separator. In passing through heat exchanger 0, the mixture is further heated to a temperature of 340 F. by heat exchange with the fresh residuum passing to the apparatus from the lubricating oil still. Exchanger (or steam heater) 1 is provided to supply any additional heat which may be necessary. For instance, if a crude having no extremely high boiling fraction is being distilled in the lubricating oil stills, the bottoms will not, of course, be so highly heated. In this case it may be necessary to supply additional heat by means of heater 1. In such a case, heat exchanger 13 may be eliminated, since heat exchanger a will be effective to reduce the residuum to the temperature required for mixing with water in mixer c.

In some cases it may be advisable to cool the residuum before it is fed to the apparatus and store it. In this case it would be necessary to heat the oil preparatory to admission to mixer c.

The separator g has a capacity equal to that of a three hour through-put of residuum and water, that is, if the water-residuum through-put is 5,000 gallons per hour, the capacity of the separator 9 would be in the neighborhood of 15,000 gallons. This large capacity is necessary to provide sufficient time for the soap solution to separate from the asphalt. As before explained, the emulsion of residuum and water is stable, at atmospheric pressure, up to the boiling point of water. This fact makes separation an extremely difficult operation. In order to effect separation, the mixture is heated to about 350 F. and is maintained under a pressure of 120 pounds per square inch or more. This pressure is sufiicient to prevent vaporization of the water at the temperature given, and is effective to cause a separation of the asphalt and soap solution when the mixture is maintained in a substantially quiescent state. Since the capacity of the separator g is equal to three or more times the hourly throughput, the mixture must remain in the separator for a period of time which is sufficient to cause a separation of the asphalt and soap solution. Since the asphalt has a specific gravity less than that of water, it rises to the top and the soap solution settles to the bottom. The particular separator 9, shown in the drawings, is also conducive to a thorough separation of soap and asphalt due to its T-shape construction. In order to provide for the proper efilux of the two constituents, there is provided a ball float 35 connected by proper linkage with a valve 3? in the soap solution outflow line 5. The ball 3% and controlling linkage are so regulated that the ball remains at the interfacial layer between the soap solution and separated asphalt. This arrangement prevents a too rapid withdrawal of either the soap solution or asphalt.

The asphalt, which is almost water free, passes out through line 5 and enters the dehydrator h, line 5 being provided with a pressure relief valve for stepping down the pressure to a point which will permit the evaporation of any water contained in the asphalt. This water vapor is passed out of the dehydrator through line 38 and the dehydrated asphalt is removed through line 39. Both lines 38 and 39 are provided with control valves so that the pressure within the dehydrator it may be properly regulated. The asphalt flowing out through line 39 is soap-free and therefore non-emulsiflable and is in condition for blowing, etc., to render it usable as a road building material, roofing material, etc., and when properly treated forms a high grade asphalt.

The soap solution flowing out through line 6 passes through heat exchanger e wherein it preheats the residuum-water mixture flowing to the separator, and then flows through line 1 to heat exchanger (1' wherein it exchanges heat with cold water flowing to the mixer c, as already described. The soap solution has a temperature of about 340 F. on leaving the separator, is cooled to about 250 F. in exchanger e and is further cooled to about 110 F. in exchanger d, whence it flows to storage tanks 8.

While in the preferred practice of the process the flow of the mixture into the gravity separator g and the outflow separated asphalt and impure soap solution therefrom are absolutely continuous, such inflow and outflow may be less desirably more or less intermittent. In claiming a substantially continuous inflow and outflow I do not mean to necessarily exclude such interruptions of the flow as would not convert the process into one in which the separation is a batch separation. There are certain more specific features of the process, however independent of the provision for substantially continuous operation which afford advantages over the process of my prior application, such as the separation of the purified asphalt and the impure soap solution.

When starting up the apparatus, a complete converted to acids.

separation of the mixture used primarily to fill the system will not be effected and this mixture should therefore be recycled. This recycling is effected by diverting soap solution, containing unseparated asphalt, from line l through branch line 40 to the mixer c. In this operation the valve in line 5 is closed to prevent efflux of unseparated material from the top of the separator.

For some uses it is desired to provide an asphalt-soap mixture containing a predetermined proportion of soap. For this purpose line i is also connected, by means of valve-controlled branch line 4 l with an evaporator a. This evaporator serves to vaporize the water contained in the soap solution. The vapor is passed off through line 42 and dehydrated soaps off through line 43 to line 29 where it mixes with soapless asphalt from dehydrator h. The resultant product is, for example, an emulsifiable road oil. The

I. asphaltic residuum as it comes from the lubricating oil stills contains too much soap for use as a road oil and since it is impossible to remove only a. small portion of the soap economically, and difficult to remove only a predetermined proportion, it is much more practicable to remove all of the soaps and then add a portion of the removed soaps to the dehydrated asphalt. This mixture of soap and asphalt may, if desired, be cut back with a mineral oil of the proper viscosity.

The soaps contained in solution in tank 8 are very impure, since they contain asphaltic compounds which cannot be separated by any physical process but require a chemical treatment. In order to purify these soaps, they should be first To convert the soaps contained in solution into acids and separate them from the large amount of water in which they are dissolved, they are passed through line it by means of the pump contained therein into the batch agitator It. To the soap solution in the agitator it there is added the proper quantity of sulphuric or other suitable acid to react with and precipitate any asphaltic products and to break down the soaps and convert them into the petroleum fatty acids. After the proper amount of acid has been added to the agitator, air is admitted through line 29 to cause the agitation of the mixture and steam may be admited to coil 28 to maintain the materials at the desired temperature. When the reactions are complete, the

air supply for agitation is cut oif and the material within the agitator is permitted to assume a quiescent state. This causes settlement of any sludge, formed by the reaction of the sulphuric acid on the asphaltic material, to the bottom of the agitator and also causes a formation of two liquid layers, a lower layer of water and an uper layer of petroleum acids. These acids are not fluid at normal temperature, and therefore should be kept heated by means of steam coil 28. After settling has taken place, and the acid and water layers are distinct, the sludge and water are drawn off through lines H and I2, leaving only the raw petroleum acid within the agitator. If these acids are to be purified immediately by vacuum distillation, they are immediately transferred to the distilling apparatus without cooling. However, since this part of the process is a batch process it is usually not practicable to distill them immediately. They are therefore admixed with a light oil, which may be an animal, vegetable, or mineral oil, but which is preferably a mineral oil, for instance one having a viscosity of 100 at 100 F., in such amount as to assure their being fluid at normal temperature. Such oil' may be supplied from tank 26 through line 25. After such addition of light oil is made, the petroleum acid and oil mixture is transferred to storage tank M through lines II and I3.

When a sufficient quantity of raw petroleum 1 acids have been collected in tank I4, they are removed through line I5 by means of pump shown, to the vacuum distillation unit 11. The bottoms from this vacuum distillation are removed through line l6 to storage tank I1, and are used for fuel oil, etc. The finished acids are removed from the vacuum distillation process through line l8 to tank I9.

These acids, which may be fractionally condensed in any number of cuts, vary from light straw color in the lightest cuts to dark red in the heaviest cuts. The saponification values of the cuts also vary so that the various cuts may be blended as desired to form a product of predetermined color and saponification number.

When it is desired to make up a batch of cutting oil, insecticide, or any other material for which the use of these petroleum acids is practicable, they are removed through line 20 to agitator m. They are therein heated by means of the steam coil 30 and have added thereto a further quantity of light mineral or vegetable oil of, say, 100 viscosity at 100 F. When the oil and petroleum acid are completely mixed and heated, sodium hydroxide solution is admitted, through line 32, from tank 34. This addition of sodium hydroxide causes a re-saponification of the petroleum acids in admixture with the light oil. After the saponification reaction is complete, the mixture is heated in order to vaporize water added with the sodium hydroxide and to vaporize any water formed by the saponification reaction. After all water has been vaporized, the soap and oil mixture is removed through line 22 to storage tank 2 i. This mixture is miscible with watersubstantially in all proportions at any temperature.

The pure petroleum acids which are obtained after settling the sludge products and water in agitator k belong to several series of organic acids. Of the acids of the series having the general formula, CnH2n602, there are three represented which have the formula:

Of the acids having the general formula CnH2n802,

there are three which have the formula:

Of the acids having the general formula CnH2nl0O2,

there are two represented which have the formula The molecular weights of these acids run from 259.5 to 372.

By way of a specific example, there is given below a resume of the process giving various figures for the input of materials and the resultant products obtained, based on an hourly throughput. There are charged to the apparatus shown in Fig. 1, 3500 gallons per hour of an asphaltic residuum remaining after the distillation of lubricating oil and lighter fractions from crude oil. To these 3500 gallons per hour there is added water to the amount of 5250 gallons and the two are thoroughly combined in the mixer c, forming an emulsion of 8750 gallons. On separation of the asphalt and soap solution there is obtained 3010 gallons of substantially dehydrated soapfree asphalt, and 5740 gallons of impure soap solution.

Agitator k is charged with 5740 gallons of soap solution containing 490 gallons of impure soaps. To this solution is added per barrel of solution, 4.67 pounds of 66 B. (98%) sulphuric acid, which is just sufiicient to break down the soaps and make the solution slightly acid. After the sludge and water, amounting to about 5250 gallons, have settled from the soap layer and have been drawn off, there are added to the remaining acids, amounting to about 490 gallons, 245 gallons of a light oil having a viscosity of 100 at 100 F. After thorough mixture of oil and acids has been efiected, the mixture is drawn off to storage. The vacuum distillation unit p is then charged with 735 gallons of the oil-petroleum acid mixture. This mixture has a saponification Value of about 35 mg. KOH. After vacuum distillation to purify the petroleum acid, it will be found that about 367 gallons of the original stock remain as bottoms and about 367 gallons have been taken over as finished petroleum acids and oil. This finished mixture has a saponification value of 30-40 mg. KOH.

Agitator m is then charged with 367 gallons of the mixture of finished petroleum acid and light mineral oil, which is sapom'fied by the addition of 26 gallons of 30% NaOH (Baum gravity 360). After saponification has been completed, there is added 300 gallons of light mineral or vegetable oil having a viscosity of 100 at 100 F. After complete admixture, the finished soap-oil solution is drawn off to storage.

What I claim and desire to protect by Letters Patent is:

1. The process of producing, from soap-containing asphaltic petroleum residuum, purified asphalt and purified organic acids, which comprises flowing said residuum and water toward a common locus and mixing the same, imposing a superatmospheric pressure thereon, substantially continuously flowing the resultant mixture to a container of suificient capacity to allow gravity settlement and therein maintaining the mixture at an elevated temperature but under a superatmospheric pressure sufficiently high to prevent boiling with resultant re-entry of the separated constituents into the emulsion or solution stage, separately substantially continuously outflowing the separated soap-free asphalt and the impure soap solution, agitating the impure soap solution with a mineral acid and separating water and acid sludge from the organic acids thereby formed, and separating said organic acids from impurities associated therewith.

2. The process of producing, from soap-containing asphaltic petroleum residuum, purified asphalt and purified organic acid soaps, which comprises flowing said residuum and water toward a common locus and mixing the same, imposing a superatmospheric pressure thereon, substantially continuously flowing the resultant mixture to a container of sufiicient capacity to allow gravity settlement and therein maintaining the mixture at an elevated temperature but under a superatmospheric pressure sufficiently high to prevent boiling with resultant re-entry of the separated constituents into the emulsion or solution stage, separately substantially continuously outflowing the separated soap-free asphalt and the impure soap solution, agitating the impure soap solution with a mineral acid and separating water and acid sludge from the organic acids thereby formed, separating said organic acids from impurities associated therewith, and re-saponifying the purified organic acids.

3. The process of producing, from soap-containing asphaltic petroleum residuum, purified asphalt and purified organic acids, which comprises fiowing said residuum and water toward a common locus and mixing the same, imposing a superatmospheric pressure thereon, substantially continuously flowing the resultant mixture to a container of suflicient capacity to allow gravity settlement and therein maintaining the mixture at an elevated temperature but under a superatmospheric pressure suificiently high to prevent boiling with resultant re-entry of the separated constituents into the emulsion or solution stage, separately substantially continuously outflowing the separated soap-free asphalt and the impure soap solution, converting the soaps of the impure soap solution to organic acids by agitation with a mineral acid, adding oil and separating water and sludge from the organic acids and oil, and distilling off the organic acids and oil from the impurities associated therewith.

4. The process of producing, from soap-containing asphaltic petroleum residuum, purified asphalt and purified organic acids, which comprises flowing said residuum and water toward a common locus and mixing the same, imposing a superatmospheric pressure thereon, flowing the resultant mixture to a separate locus and there, at a substantially higher temperature while maintaining the pressure suificiently high to prevent boiling with resultant destruction of the soaps or the re-entry of the separated constituents into the emulsion or solution stage, effecting gravity settlement, separately outflowing the separated soap-free asphalt and the impure soap solution, agitating the impure soap solution with a mineral acid and separating water and acid sludge from the organic acids thereby formed, and separating said organic acids from impurities associated therewith.

5. The process of producing, from soap-containing asphaltic petroleum residuum, purified asphalt and purified organic acid soaps, which comprises flowing said residuum and water toward a common locus and mixing the same, imposing a superatmospheric pressure thereon, flowing the resultant mixture to a separate locus and there, at a substantially higher temperature while maintaining the pressure sufiiciently high to prevent boiling with resultant destruction of the soaps or the re-entry of the separated constituents into the emulsion or solution stage, eiTecting gravity settlement, separately outflowing the separated soap-free asphalt and the impure soap solution, agitating the impure soap solution with a mineral acid and separating water and acid sludge from the organic acids thereby formed, separating said organic acids from impurities associated therewith, and re-saponifying the purified organic acids.

6. The process of producing, from soap-com taining asphaltic petroleum residuum, purified asphalt and purified organic acids, which comprises fiowing said residuum and water toward a common locus and mixing the same, imposing a superatmospheric pressure thereon, flowing the resultant mixture to a separate locus and there, at a substantially higher temperature while maintaining the pressure suiiiciently high to prevent boiling with resultant destruction of the soaps or the re-entry of the separated constituents into the emulsion or solution stage, effecting gravity settlement, separately outflowing the separated soap-free asphalt and the impure soap solution, converting the soaps of the impure soap solution to organic acids by agitation with a mineral acid, adding oil and separating water and sludge from the organic acids and oil, and distilling off the organic acids and oil from the impurities associated therewith.

7. The process of producing purified asphalt from soap-containing alphaltic petroleum residuum which comprises flowing said residuum and water toward a common locus and. mixing the same, imposing a superatmospheric pressure thereon, substantially continuously flowing the resultant mixture to a container of suflicient capacity to allow gravity settlement and therein maintaining the mixture at an elevated temperature but under a superatmospheric pressure sufiiciently high to prevent boiling with resultant reentry of the separated constituents into the emulsion or solution stage, separately substantially continuously outflowing the separated soapfree asphalt and the impure soap solution, dehydrating outflowing soap solution and flowing dehydrated soaps to the outflowing soapless asphalt in predetermined proportions to form an emulsifiable oil containing a predetermined proportion of soap less than that contained in the original asphaltic petroleum residuum.

8. The process of producing purified asphalt from soap-containing asphaltic petroleum residuum which comprises flowing said residuum and water toward a common locus and mixing the same, imposing a superatmospheric pressure thereon, flowing the resultant mixture to a separate locus and there, at a substantially higher temperature while maintaining the pressure suificiently high to prevent boiling with resultant destruction of the soaps or the re-entry of the separated constituents into the emulsion or solution stage, effecting gravity settlement, separately outflowing the separated soap-free asphalt and the impure soap solution, dehydrating separated soap solution and adding the dehydrated soaps to the soapless asphalt to form an emulsifiable oil containing a predetermined proportion of soap less than that contained in the original asphaltic residuum.

9. The process of producing, from soap-containing asphaltic petroleum residuum, an emulsifiable road oil and purified organic acids, which comprises flowing said residuum and water toward a common locus and mixing the same, imposing a superatmospheric pressure thereon, substantially continuously flowing the resultant mixture to a container of sufiicient capacity to allow gravity settlement and therein maintaining the mixture at an elevated temperature but under a superatmospheric pressure sufficiently high to prevent boiling with resultant re-entry of the separated constituents into the emulsion or solution stage, separately substantially continuously outflowing the separated soap-free asphalt and the impure soap solution, dividing the outflowing soap solution into two streams, dehydrating the soap solution of one stream and mixing it with outfiown soapless asphalt, agitating the soap solution of the other stream with a mineral acid and separating water and sludge from the organic acids thereby formed and separating said organic acids from impurities associated therewith.

10. The process of producing purified asphalt from soap-containing asphaltic petroleum residuum which comprises flowing said residuum and water toward a common locus and mixing the same at a relatively low temperature and at a relatively low superatmospheric pressure suflicient to prevent boiling at such temperature, flowing the resultant mixture to a separate locus and there, at a temperature and pressure substantially higher than the temperature of mixing and at a pressure sufficiently higher than the temperature of mixing to prevent boiling with resultant destruction of the soaps or the reentry of the separated constituents into the emulsion or solution stage, effecting gravity settlement, separately outflowing the separated soapfree asphalt and the impure soap solution, reducing the pressure on the asphalt to effect its dehydration, and without reduction of pressure cooling the outflowing stream of the impure soap solution.

11. The process of producing purified asphalt from soap-containing petroleum residuum which comprises flowing said residuum and water toward a common locus and there mixing the same at a relatively low temperature under a pressure sufliciently high to prevent boiling, substantially continuously flowing the resultant mixture to a container of sufficient capacity to allow gravity settlement and in the course of the flow of said materials heating the same to a temperature sufficiently higher than the temperature of mixing to throw the soaps out of solution or emulsion with the asphalt impurities associated therewith but not high enough to effect boiling at the existing pressure and consequent destruction of soaps, continuing to maintain the mixture in the container at a temperature not substantially below the temperature to which it has been heated while continuing to maintain it under a boiling temperature at the existing pressure, allowing gravity settlement in the container, separately substantially continuously outflowing therefrom the separated soapfree asphalt and the impure soap solution, reducing the pressure on the asphalt to effect its dehydration and without reduction of pressure cooling the impure soap solution.

HARRY F. ANGSTADT.

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