Патент USA US2122260код для вставки
June 28, 19u38. l.. c. MooRE ET AL 2,122,260 DEODORIZING AND BLEACHING OILS Filed Dec. 6, 1932 2 Sheets-Sheet 1 (klamm ATTORNEY. June 2s, 193g. L, `¢_ MOQRE ET AL 2,122,260 DEÓDORIZING AND BLEACHING OILS " " ß www ATTORNEY. 2,122,260 Patented June 28, 1938 UN 2,122,260 f DEÜDORIZING Landon C. Moore, Dallas, and Arthur C. Norman, deceased, late of New Boston, by Smithia S. Norman, executrix, New Boston, Tex. Application December 6, 1932, Serial No. 645,882 Ll" BLEACIHIHNG @MJS 7 Claims. This invention particularly relates to the bleaching of the vegetable oils, cottonseedy cocoa nut, soya bean, sesame and corn oils. It further relates to the bleaching and deodorizing of said 5 oils. (Ul. 87-12) bleaching and the deodorizing of said oils. The operation is eñected in a system, which is closed to exclude air and which is maintained under vacuum effect during the operation, (a) by heat ing the oil to a critical temperature substantially 5 as high as can be employed with substantially no volatilizing, scorching or change in the essen at a reduced cost, and to effect the bleaching and tial characteristics of the oil as, for example, by deodorizing of said oils in a combined and efli- _ polymerization, while an inert gaseous medium Primary objects of the invention are to ef fectively bleach vegetable oils specified, to do so 10 cient manner. It is Well known to those skilled in the art of producing certain edible vegetable oils that a crude oil is usually subjected to three general processing steps generally termed refining, bleaching and deodorizing. Of these, the so " called reñning step consists of mixing the crude oil with an aqueous solution of caustic soda so as to form probably, sodium salts with the free acids, tri-glycerides and others of the impurities present in the crude product and then separat “ ing the purified oil from the aqueous portion of the mixture and any precipitated solids so as to yield a product free from moisture and precipi tated or solid substances. The so-called bleach , - ing step consists of warming the reñned oil, em “ ploying and intimately mixing with it a solid decolorizing reagent such as fuller’s earth and then separating the solids'from the oil by means of suitable filtration apparatus, so as to yield a 30 product of much improved color and free of solid impurities. The so-called deodorizing step includes heating the reñned and bleached oil to and holding it at a temperature of substantially 325 degrees Fahrenheit in a closed vessel under a . - high vacuum and simultaneously blowing super ` other solid bleaching reagents together with the loss of oil attendant to the use of such reagents. Thus, too, it has for an objective the combin ing of what has heretofore constituted two sep arate and distinct and unrelated operations, one for bleaching and one for deodorizing, into sub Thus the nature of the invention may be said to reside in heating the oil to be treated in a 35 closed vessel to a temperature as high as can jectionable ingredients and to yield an oil of suitable taste and odor. The use of a solid decolorizing reagent in the bleaching step of the prior art process is attend be done without danger of volatilizing the oil or burning it, while agitating the oil to disperse an ed (a) by an appreciable expense for said re action of a vacuum. The essence of the present invention may be said to reside in the employment of heat, under certain requisite conditions, as the essential ele ment in effecting the bleaching of the above speciñed reñned oils; and further in effecting in a substantially single processing operation the 0 stantially a single operation of steps. heated steam through the hot oil to volatilize ob agent which generally is used only once and then discarded, and also (b) by an appreciable loss of oil with the discarded reagent. „- is continuously introduced into the system and 10 is thoroughly dispersed through or contacted with the oil within same, and then (b) by re ducing to and holding for a period of time at a somewhat lower point, the temperature of the oil in the system while continuing the main~ 1 tenance of the vacuum and the introduction and dispersion of the inert gas, and then (c) by ñnal ly cooling the oil while continuing to maintain the oil out of contact with the air as by the main tenance of the vacuum eiîect. The larger por- 20 tion of the decolorizing eiîect with some deodor izing is effected in the first step of the operation, and a larger portion of the deodorizing with some decolorizing is effected in the second step. Thus the invention has for a primary objective 2 the elimination of the use of fuller’s earth and inert gaseous medium thoroughly therethrough, during which operations, the oil is exposed to the 40 The invention may be carried out by exposing the oil, or oil bearing mixture being treated, simultaneously or concurrently to bleaching and to deodorizing actions without the use in the zone 5 of treatment of solid bleaching agents such as fuller’s earth, bone char, or activated carbon. This bleaching and deodorizing is accomplished by raising the temperature of the oil while under 50 2 2,122,260 the action of a vacuum or vacuum effect, to a critical bleaching temperature range within which the color substances are affected without burning or volatilizing the oil and within which some portion of the odorous organic substance is removed by volatilization. The range of oper ating temperatures within which the decoloriz ing just referred to is carried out and within , pipe line I1 but are iprovided with outlet valves I8, I8, 20 and 2| respectively. 'There is a pumpÍ 22 in 'the pipe line capable of pumping hot oil under a vacuum. From the pump 22 leads a pipe 23 to the heater II. From the heater, leads an oil pipe 24 feeding to the kettles with a valved inlet for each kettle 25, 26, 21 and 28 respectively. A vacuum pipe-line is indicated by 30 with a which the substantial decolorizing operations are valved connection 3|, 32, 33, 34 and 35 for each 10 confined, is thus referred to herein as the oper of the kettles and cooler-respectively. A steam ative critical bleaching-temperature range. Then lineyis indicated at 26 with a valved connection 10 While still maintaining the oil under vacuum, 31, 38, 39 and 40 for each kettle respectively, and Washingout volatilizable impurities, odoriferous each such connection is provided with a steam or otherwise,` from the oil by means of an inert 15 gas, such as steam. And finally cooling the treat ed oil while still under a vacuum. gauge 4|, 42, 43 and 44 respectively. 45, 46, 41 and 48 represent a vacuum gauge `on each kettle respectively; 49, 50, 5| and 52a thermometer; In the interest of clarity it is herein pointed ' and 53, 54, 55 and 56 a gauge glass and sampler. The steam line 36 .has a feed inlet pipe 51 and also a valved outlet 58 to an injection device 59 out that the term “bleaching”, as employed in describing this invention, may be defined as a 20 change in the color of a refined vegetable oil essentially the equivalent of that change obtained when that oil is ‘subjected to the official bleach ing test as set forth in “Rules Governing 'I‘rans actions‘Between Members of the National Cot-25 tonseed Producers Association Incorporated, as adopted at New Orleans, La., May 12-13-14, 1930,” p. 147, rule 275, section 2, paragraphs a and b, the color of the bleached oil being de termined as set forth in section 1 of this rule 30 275. 'I‘he bleaching procedure set forth in said rule 275, may be essentially described as follovvsz--A Using apparatus as set forth in the rule, weigh adjacent the pump 22. The oil line I1 has an inlet 60 for new oil to be treated controlled by a three-way valve 6|. The oil line |1 terminates at a pump 62 for im pelling finished oil from a kettle along pipe 63 to the cooler I6. A valve 64 is provided in the 25 pipe 63, >and another valve 65 is provided in pipe I1. Each kettle has in its bottom a steam dispensing device such as a spider 66 having substantially radial pipes 61 through which steam is fed from steam pipe 31 for instance, and the 30 steam is emitted through apertures in the bottom or underside of the pipes 61. The cooler I6 -has an outlet or discharge pipe 68 leading to a filter 300 gms. of refined oil into a refining cup, heat , or filter-press which is not shown. The cooler 35 to 120° C. and add 6 per cent. of oiiicial fuller’s may be provided with cooling coils 69 and an 35 earth. Stir mechanically at 250, R. P. M. (plus or minus 10) for ?lve minutes, not allowing tem perature to fall below 105° C'. and filter through filter paper. After suiiicient oil has passed the 40 filter to insure clearness, collect a sample for color reading. Cool and read immediately. The oiiicial fuller’s earth prescribed above is to be obtained from the secretary of the Ameri can Oil Chemists Society as set forth in the rule 45 (120° C. is equivalent to 248° F.-105° C. is equiva lent to 221° F.). . - The invention may be carried out in different apparatus but only one arrangement thereof is illustrated in Fig. 1 of the accompanying draw 50 ings and even that arrangement is shown more orv lessrdiagrammatically. The curve A-B--C of Fig. 2 of the accompanying drawings illustrates substantially a type of temperature-time rela tionship employed in effecting the invention by 55 the combined steps of bleaching and deodorizing and as Vapplied ,to cotton seed oil. The curve D--E-F of Flug. 2 substantially illustrates the col or-time relationship resulting from the use of the time temperature relationship illustrated by 60 the curve A-B-C. The curve M--N-O of Fig. 3 of the accom panying drawings is embodied herein to illus trate an application of the invention as applied ’ to cottonseed oil, wherein the bleacher step is 65 the main feature involved. The curve X--Y-Z of this Fig. 3 substantially illustrates the corre sponding color-time relationship illustrated by the curve M-N-O. In the drawings there, are shown an oil heater 70 II of any mutable type, a primary oil yheating tank or kettle I2 and a.v plurality of secondary oil treating tanks or kettles I3, It and I 5, usu ally similar to kettle I2. And associated with the kettles, is a cooler I6 `of any emcient type. 75 .The kettles Yare all connected to an oil discharge agitator 10, although other types of coolers may be used. The operation of this apparatus‘on refined cot ton seed oil, for instance, is as follows: Through oil inlet 60, oil is fed to the system including pri 40 mary kettle I2 and heater II until kettle I2 is about half full. , The vacuum line 30 is opened to the kettle I2 and its contents by means of valve 3| so there is a vacuum of approximately 29" acting on the oil in the kettle. . The pump 22 causes continuous'circulation of the oil from the kettle I2 through the heater |I and back to the kettle through pipes 24 and 25. Thus the oil in kettle I2 is gradually heated to 50 the desired temperature which for cotton seed oil is about 460“ F. In this connection see curve A-B-C of Fig. 2 which is illustrative of the steps described in this paragraph and the immediately following portions of this specification. During this circulation of oil from kettle to heater and return, it is helpful to inject steam into the oil going to the heater, for instance by injector 5B or other similar device, located preferably ahead 0f the pump. This steam has several functions 60 but the prime one is to keep the oil in motion in flowing through the heater so that none of it will stagnate in the heater and be burned, in other words, there is caused continuous circula tion of the oil whereby it repeatedly flows through 65 the zone where the heating thereof is most in tense and during which flow of the oil through or past said zone there is effected suiiìcient mo tion so that as indicated none of the oil being heated will stagnate or become pocketed in the 70 heater or in any section thereof and thus be burned or scorched. Then this hot bleached oil is conveyed to a sec ondary kettle I3 by closing valve 25 and opening 75 3 2,122,260 valve 26, since the pump 22 causes the necessary circulation. During this transfer, the tempera ture of the oil in the secondary kettle I3 falls to about 435° F. superheated steam is diffused or dispersed through the oil or in other words is caused to iiow into the oil on its way through the oil, by means of valved connection 38 and its asso ciated spider and arms. representatively indicated at 66 and 6l. The oil may stayin kettle I3 for an interval as long as three hours. meanwhile being exposed to action of a vacuum through pipe 30 and valve connection 32. The time of detention in the secondary kettle depends upon the degree of deodorization required of the ñnished oil, since deodorization goes on progressively. The temperature is indicated on thermometer 50, the steam pressure on gauge 42 and the vacuum on gauge 46. After a suitable time the steam supplied to kettle I3 may be lessened while in creasing the vacuum, if possible in order to cool the oil down to say 350° F. Then the oil is pumped through pump 62 and pipe 63 to the cooler I6 by a suitable manipulation of the var ious valves. Here the oil while still .under a vac therethrough aids this action. AThe use of the vacuum aims to prevent oxidation of the oil at the high temperatures to which it is heated. It also assists in volatilizing and removing from the place of volatilization the odorous impurities of the oil being treated. The various vegetable oils listed lend them selves to this deodorizing and bleaching treat ment, which eliminates the use of bleaching agents such as i'uller's earth or carbon. But each oil seems to have different requirements as to temperature that must be reached for best re sults. Each oil must be raised to a tempreature as high as possible without reaching its liash point, for it is imperative that during treatment the oil is not volatilized. To determine this, the flash point of the oil to be treated is observed and a factor of safety is deducted from that point. This factor has to be determined by tests to be sure of it. Some oils which respond to this treat ment and their effective temperatures are: Degrees Fahrenheit approximately Cotton seed oil ______________________ __ 450-470 Seya. bean oil _______________________ __ 475-480 uum is cooled to approximately 150° F. where upon it is discharged through pipe B3 to a ñltra tion stage. The quicker the cooling takes place, the better for the flavor of the treated oil. While oil in the kettle I3 is being treated, pri 30 mary kettle I2 is refilled with oil which is heated, as the ñrstlbatch was. and then it is transferred to secondary kettle I4 for further treatment as put. The bleaching takes place in a critical range of high temperatures whereas the deodor described for the batch in kettle I3. Still an other batch is heated in primary kettle I2 and ization takes place concurrently but over a much longer period of time during which the oil is then transferred to secondary kettle I5. After kettle I3 has been emptied by having its treated oil pumped to the cooler I6, it is then maintained at elevated temperatures but lower than those in the bleaching range. If the oil is to ready to have a fresh batch of heated oil from kettle I2 pumped to it, and so on, each sec Ll ondary kettle I3, I4 and I5 having heated oil from primary kettle I2 pumped thereto respec tively, and from each kettle to the cooler. Thus by using a battery of kettles individually batch operated, the battery as a whole gives continuous treatment of oil. In order to insure that the bleached oil is free of solid impurities which may be therein it is manifest that it may be filtered after the cool lng. This treatment simultaneously or concurrently bleaches and deodorizes the oil. Such action is Sesame oil __________________________ __ 460-470 Cocoanut oil ________________________ __ 400-410 Corn oil ____________________________ __ 450-460 The time of treatment varies with the oil and with the use to which the finished oil is to be 30 be used for non-edible purposes, it need not be deodorized so completely and therefore for not so long a time as if it were to be eaten. A curve indicative of this process is illustrated in Fig. 3 40 and is indicated M-N--O. But taking cotton seed oil for an example and as shown by commer' cial scale operation typiñed by the curve A--B-C of Fig. 2, a satisfactory time of treatment is an hour in the primary heater to reach bleaching temperatures and three hours in the secondary kettle at the lower deodorizing temperatures. After such treatment, the cotton seed oil has its color changed from a red substantially towards white and the treated oil is neutral in flavor and produced by raising the temperature of the oil to odor. In order that a reader of this patent may have a point within a range at which bleaching is ready reference for comparative purposes to flash effected without fundamentally affecting the oil in any deleterious manner as by volatilizing, poly point temperatures for certain oils there are in serted in this specification certain tables found merizing. or oxidizing the oil, then maintaining on page 211 of Volume II, First Edition of “Inter- . the oil at elevated but lesser temperatures for a national Critical Tables” prepared by the Na tional Research Council and published for said council by the McGraw-Hill Book Company, Inc.. 60 New York, 370 Seventh Ave., in 1927. period to produce deodorization, meanwhile ex posing the oil to the action of a vacuum and dis persing through the oil superheated steam. The high temperature causes precipitation or change in the color imparting substances. These are washed out or eliminated from the oil by dis persing the superheated steam through the body of the oil. Their removal from the oil is facilitat ed by means of the vacuum. The maintained tem peratures, which may be somewhat lower than the higher temperature range last above-men tioned, further-s volatilization of odorous free fatty acids and other impurities, but not of the oil. The temperature range within which this substantial deodorizing is carried out may be re ferred to as the deodorizing-temperature range. 75 Agitation oi- the oil by the steam being diffused On said page 211 thereof one ñnds the flash point temperature for cottonseed oil according to one portion of the table as having an average value of 523.0 degrees F. or 272.7 degrees C.,.with extreme values given as 500 degrees to 540 de grees F. or 260 degrees to 282.22 degrees C., while according to another portion of the table the flash point of cottonseed oil is listed as 582 degrees F. or 305.6 degrees C. For linseed oil in the same table-probably raw oil-_the flash point is given as 378 degrees F. or 192 degrees C., while for linseed oil boiled the flash point temperature is given as 419 degrees F. or 215 degrees C. 4 ' areaaeo ` The tables referred to and which are being quoted read as follows: the flashpoint temperature thereof whereby, dur FLASH PorN'rs or OILS AND FA'rs 1. Closed test Average value E53-âge Oil or iat 10 °F. Olive ................................... ._ 437. 5 Arctic sperm _____ __ 446. 2 Southern sperm ..... __ 457. 5 °C. 225. 2 230. 0 236. 3 °F. 410-465 390-485 420-485 Rape, Black Sea renne 464. 4 240. 2 430-490 N eat’s 470. 3 243. 5 410-540 White whale __________ _ _ 476. 0 Rape, E Indian refined__ _______ __ Cottonseed _____________________________ __ 478.6 523.0 246. 4 248. l 272. 7 410-510 50G-540 __________ __ 430-530 Flash point Fire point Oil or fat 25 378 419 192 215 Maize (com)_ ____________________________ _ Sperm, No. 2__ _ Prime lard _ . _ _ 35 572 468 300 242 468 242 518 523 541 270 273 283 'i-ìëâ-ì- “2537 574 302 _ 644 340 Cottonseed ______________________________ __ 644 340 This invention can be used to effect the required bleaching of the oil while either completely or incompletely deodorizing it. Or it can be used on already partially bleached oil whereby com pletion of the required bleaching and the deodor 40 izing can be carried on simultaneously. The process of this invention can be carried out on the reñned oils listed; on mixtures thereof or any of said oils listed or mixtures thereof with hydrogenated or semi-hydrogenatecl products 45 thereof; and on mixtures of said oils in or any of’ said oils or products thereof on the one hand and stearin on the other. 'I'he process can be carried out in other apparatus than that shown herein so long as the temperature, time, gas and vacuum 50 requirements are met. By way of example, the seed oil lies between approximately 450 and ap proximately 470 degrees Fahrenheit, maintaining the temperatures of the oil within said range for 10 a period of time which is insuñiciently long for the oil being so heated to be changed funda mentally as by volatilization, polymerization, or burning, but long enough so that by virtue of said heat treating there .is effected a bleaching action in which the objectionable color characteristics of the oil are substantially destroyed; and which method also comprises subsequently cooling the ' -, 2. The method of treating refined cottonseed 20 oil and analogues thereof as defined in and by claim 1, and further carried out in such a man ner that it comprises cooling the oil to a deodoi’-, izing-temperature range extending between ap proximately 15 and approximately 120 Fahren 25 heit degrees below the temperatures employed within said bleaching-temperature range, main taining the oil at temperatures within said de odorizing-temperature range for a period of time sufilciently long to eiîect substantial reduction in 30 the odorous characteristics of the oil, maintain ing the oi-i under vacuum effect while substan tially free from the influence of gases of oxidizing nature during said last mentioned period, and also during said last mentioned period flowing an 35 inert gaseous medium as superheated steam into l _ and through said oil; which said operations, here by deflned as being carried out while the oil is at temperatures within said deodorizing-tem perature range, precede what is defined in said 40 claim l as cooling the oil before exposure to air. 3. In the treating of refined cottonseed oil in order to overcome objectionable color character istics thereof and in order to realize a decoloriz ing process according to which the objectionable 45 color characteristics are overcome Without the employment as an essential part of the decolor izing process of a solid bleaching agent such as fuller's earth, bone char or activated carbon, the method which comprises heat treating the oil 50 l oil in the primary kettle may be heated indirectly while agitating it, While dispersing therethrough instead of directly, and instead of primary and a flow of an inert gaseous medium as steam, while secondary kettles, a single kettle can be used if the volume of oill to be treated does not warrant 55 more than one kettle. What is claimed is: 1. In the treating of refined cottonseed oil and analogues thereof such as are deñned herein in order to overcome objectionable color character 60 istics thereof and in order to realize a decoloriz ing process according to which the objectionable color characteristics are overcome without the employment as an essential part of the decolor izing process of a solid bleaching agent such as 65 fuller’s earth, bone char or activated carbon, the method which comprises heat treating the oil while agitating it, while dispersing therethrough a flow of an inert gaseous medium as superheated steam, while maintaining thereon' a vacuum 70 effect, and While maintaining the oil substantially e ing said treating as carried out, there is substan tially avoided volatilizing, polymerizing or burn 5 ing of the oil during said heat treating, which critical range as employable for reñned cotton oil before exposure to air. 2. Methods not stated 20 Linseed ................................. _. Linseed, boiled __________________________ _. high as possible but which provides a factor of safety for the particular oil being treated below maintaining thereon a vacuum eiîect, and while maintaining the oil free from the inñuence of gases of oxidizing nature, which said heat treat 55 ing involves heating the oil to temperatures with in but not above an operative critical bleaching temperature range extending between approxi mately 450 and approximately 470 degrees Fahrenheit, maintaining the temperature of the 60 oil Within said range for a period of time which is insuñiciently long for the oil being so heated to be changed fundamentally as by volatilization, polymerization, or burning but long enough to effect a bleaching action the result of ywhich is 65 that the objectionable color characteristics of the oil are substantially destroyed but at the most with only a slight concomitant reduction in the odorous characteristics of the oil; and which method also comprises subsequently cooling the 70 free from the influence of gases of oxidizing na oil before exposure to air. ture, which said heat treating involves heating 4. The method of treating refined cottonseed oil as defined in and'by claim 3, and further carried out in such a manner that it comprises the oil to temperatures within an operative criti cal bleaching temperature range having as its uppermost operative temperature one which is as cooling the oil to a deodorizing-temperature 75 5 2,122,260 range extending between approximately 435 and approximately 350 degrees Fahrenheit, main taining the oil at temperatures within said de odorizing-temperature for a period of time suffi ciently long to effect substantial reduction in the _ odorous characteristics of the oil While maintain ing the oil under vacuum eiîect and substantially free from the inñuence of gases of oxidizing nature, and while dispersing an inért gaseous 10 medium as superheated steam throughout the oil by flowing the same into and through said oil; which said operations, hereby defined as being carried out while the oil is at temperatures with in said deodorizing-temperature range, precede 15 what is defined in said claim 3 as cooling the oil before exposure to air. _ 5. In the treating of refined cottonseed oil ` and analogues thereof such as are‘defìned herein, in order to overcome objectionable color charac 20 teristics thereof and in order to realize a decolor izing process according to which the objectionable color characteristics are overcome Without the employment as an essential part of the decoloriz ing process of a solid bleaching agent such as 25 fuller’s earth, bone char or activated carbon, the method which comprises heat treating said oil while under a maintained vacuum effect, while it is substantially free from the iniiuence of chemi cally reactive gases of oxidizing and deleteriously 30 contaminating nature and while it is under con ditions of agitation which will prevent excessive localized overheating, which said heat treating involves heating the oil to temperatures within an operative critical bleaching-temperature range having as its uppermost operative tem perature one which is as high as possible, but which provides a factor of safety for the par ticular oil being treated below the ilashpoint temperature thereof whereby, during said treat 40 ing as carried out, there is substantially avoided volatilizing, polymerizing or burning of the oil during said heat treating; maintaining the tem peratures of the oil within said range for a period of time which is insufficiently long for the oil` 45 beingÍ so heated to be changed fundamentally as> by volatilization, polymerization, or burning, but long enough to effect in the oil a bleaching action ' the result of which is that the objectionable y, color characteristics of the oil are substantially' 50 destroyed; and which method also comprises sub sequently cooling the oil before exposure to air.` 6. The method of treating refined cottonseed'-- oil and analogues thereof, such as are defined herein, in order to overcome vobjectionable color 55 characteristics thereof, and according to which method certain objectionable color characteristics of the oil are- overcome without the employment as an essential part of the bleaching operation thereof of a solid bleaching agent such as fuller’s 60 earth, bone char or activated carbon, which said method comprises heat treating said oil while it is under the influence of vacuum and is substan tially free from the inñuence .of chemically re active gases of oxidizing and deleteriously con 65 taminating nature and under conditions which will prevent excessive localized heating, which said heat treating involves heating the oil to temperatures within an operative critical bleach ing-temperature range having as its uppermost operative temperature one which is as high as possible but which provides a factor of safety for the particular oil being treated whereby, dur ing said treating as carried out, there is substan tially avoided volatilizing, polymerizing or burn ing of the oil during said heat treating; main taining the temperatures of the oil within said 10 range for a period of time which is insufiiciently long- for the oil being so heated to be changed fundamentally as by volatilization, polymeriza tion, or burning, but sufficiently long so that incident to such a heating a bleaching action follows with a consequent overcoming of cer tain color characteristics of the oil; and which method also comprises subsequently cooling the oil before exposure to air. '1. In the treating of reñned cottonseed oil and analogues thereof such as are defined herein, in order to overcome objectionable color character istics thereof and in order to realize a decoloriz ing process according to which the objectionable color characteristics are overcome without the employment as an essential part of the decoloriz ing process of „a solid bleaching agent such as fuller’s earth, bone char or activated carbon, the method which comprises heat treating said oil While it is under the influence of vacuum and While it is substantially free from the influence of chemically reactive gases of oxidizing and deleteriously contaminating nature and while under _conditions which will prevent excessive localized heating, which said heat treating in volves heating the oil to temperatures Within an operative critical bleaching-temperature range having as its uppermost operativetemperature one which is as high as possible but which provides a factor of safety for the particular oil 40 being' treated whereby, during said treating as carried out, there is substantially avoided volatiliz ing, polymerizing or burning of the oil during said heat treating; maintaining the temperatures of the/_oil within said range for a period of time 45 which is insufficiently long for the oil being so heated to be changed fundamentally as by vola tilization, polymerization, or burning, but long yenough so that there is effected in the oil a bleach ing action the result of which is that the objec 50 tionable color characteristics oi the oil-are sub stantially destroyed; then cooling the oil to a tem perature which is within a deodorizing tempera ture range, maintaining the oil for a relatively long period of time at temperatures within said 55 deodorizing-temperature range, and during this period maintaining a vacuum eñect and dispers ing a flowing gaseous medium while intimately contacting with the oil; and which method also comprises subsequently cooling the oil before ex-Í 60 posure to air. _ LANDON C. MOORE. ARTHUR C. NORMAN, Deceased, By SMITHIA S. NORMAN, Exccutríœ.