1.ApplicationNumber: US-20246238-A
1.PublishNumber: US-2253480-A
2.Date Publish: 19410819
3.Inventor: DALY RAYMOND E.
WALSH JAMES F.

4.Inventor Harmonized: DALY RAYMOND E()
WALSH JAMES F()

5.Country: US
6.Claims:

7.Description:
(en)Aug. 1-9, 1941.l
R. E. DALY ETAL OIL REFINING PROCESS Filed April 16, 1938 TEM/2 125- 140W- fxcfss Huffm=15f4070 TIME.- .50-60 M/Ms.
L TEM/2 125 140 "f 5165.55 #UML/4540 Byfdnfaf Wills/a www b. WM;
ATTO R N EY Patented Aug. i9, 1941 OIL REFINING PROCESS Raymond E; Daly and James ,F. Walsh, Chicago,
Ill.,
assignors to American Maize-Products Company, a corporation of Maine Application April 16, 1938, Serial No. 202,462
(ci. 26o-425) s claims.
Our invention relates to the refining of vegetable oils and more particularly to a process of producing a high yield of refined corn oil of relatively low fatty acid content.
In the old, well-known processes for refining of vegetable oils such as corn oil, cotton-seed oil and the like, it has been customary to treat batches of the settled crude oi1.with a large excess of alkali while warm for the purpose of neutralizing the free fatty acids present in this oil. This neutralizing treatment, which results in the formation of soap stock commonly referred to as foots, is usually continued for a considerable period of time, for example, several hours. This prolonged contacting of the oil with large amounts of alkali also causes saponification of some of the neutral oil with formation of soap resulting in loss of this amount of oil, which is known as a refining or saponification loss.
After the neutralizingtreatment the foots or soap stock formed, by reaction of the alkali on the fatty acids and part of the neutral oil, is allowed to settle along with the caustic solution.
ments have been made upon the above described prior art process, namely, in the nature of a quick continuous process by means of which larger yields of neutral oil are obtained, that is, the saponification loss is reduced somewhat and vless neutral oil` remains in the soap stock.
Although the yield has been improved in this manner, the final oil product obtained by this process is not of as good quality as the oil obtained by the older refining processes. The oil produced by these recent processes does not fully meet the presentmarket requirements, particularly because its fatty acid content is higher than that generally desired and obtainable through 'the prior conventional procedures. One of the principal reasons for this disadvantage and commercial limitation is that in this recent quick, continuous process the oil and caustic are maintained in contact for a very short period ofv time, and although greater amounts of alkali are used to compensate for the shortened time of reaction between the oil and alkali, there is not sufficient opportunity for the alkali to neutralize all or the desired maximum amount of the free fatty acids present in the crude oil. Accordingly, an undesirable relatively large amount of free fatty acids remain in the final product.
In accordance with our present invention we have discovered a process for refining corn oil and the like by means of which the advantages of boththe prior and more recent improved reriining processes can be obtained and the dis-v 1 advantages of those processes avoided. More relatively small amount of alkali for a period of time intermediate that employed in the above described processes, and then subjecting this Ftreated oil to centrifugal action to separate the soap stock from the neutral oil, the latter will be produced in relatively high yields and of a quality that meets the present commercial requirements. This process comprises generallyy reacting the crude oil with approximately 15% to 40% excess alkali for a period of time of about 30 to minutes and at a temperature between about F. to 140 F. to effect maximum neutralization of the free fatty acids present, and at the same time produce a minimum loss of oil by saponication of the neutral oil by the alkali. After this neutralization ltreatment for a period of about one-half hour to one hour, the treated mixture is passed through a centrifuge in which the soap stock is separated from the neutral oil. The neutral oil is then advantageously subjected to a chilling operation, and if necessary, is filtered in the presence of filter-aid to remove the remaining small amounts of alkali, water and the like. After this treatment the oil is bleached, deodorized and otherwise refined in conventional manner.
As an alternative to the above process, we have found it advantageous in some instances, depending somewhat upon the percentage of impurity of the crude oil, to partially refine this oil preliminarily to' the neutralization treatment. One advantage of this preliminary refining treatment is that the lecithin content of the oil may be isolated for use, whereas if the oil is neutralized immediately, the lecithin contentI is lost.
The method of operation of our invention may be easily understood from the following more detaileddescription taken in conjunction with the accompanying drawing in which the single figure represents a' flow diagram of our process with alternatives.
Referring now tothe drawing-the crude corn oil or other similar vegetable oils, may be sub- :lected directly to the neutralizing treatment with alkali as indicated, orit may be first partially refined as shown in this flow diagram, by treating the crude oil with sodium ferrocyanide. The amount of ferrocyanide used may be varied from about 0.1% to 0.5% by weight of the oil, and we have found it practical to add to the oil an amount equal to about 0.2%- of the weight of the oil; or we may add, based on the weight of the oil, about 2% of a 10% solution of the ferrocyanide. This treatment with ferrocyanide is carried out at room temperature until a break is obtained, that is, until it is apparent that the treatment has caused some of the fatty acids and other impurities to coagulate.
Following the treatment with sodium ferrocyanide the treated oil is filtered, preferably in the presence of a small amount of filter-aid, such as diatomaceous earth or filter cel, to separate the coagulated material from the partially refined oil. The residue produced by this filtration contains a mixture of lecithin and oil, from which the lecithin may be isolated in any suitable conventional manner. The partially refined oil resulting from this treatment with the sodium ferrocyanide has its original acidity reduced to an extent of about 30% to 60% and a similar reduction in the color of the oil also takes place.
The partially refined oil, or the crude oil, if the sodium. ferrocyanide treatment has not been used, is divided into several batch, such as indicated by the three spaces in the flW diagram. Each of these batches of oil is now heated to a temperature of about 125 F. to about 140 F., a preferred temperature being about 126 F. and a suitable alkali such as caustic soda is added to each batch of oil. The alkali is added in an amount of about 15% to 40% excess of that theoretically required to neutralize the free fatty acids present in the oil. An advantageous excess is about 25%. This netralizing operation is carried on for about 30 to 60 minutes, and prefere ably about 45 minutes. If desired, each of the batches is agitated during this treatment.
After the completion of the neutralizing treatment, the oil and resulting soap stock from each batch is fed into a centrifuge or centrifuges. The size of each batch of oil is regulated so as to supply the centrifuge for about 30 to 60 minutes time. In the centrifuge the soap stock is separated from the neutral oil and this oil. is passed on to the other refining steps, including chilling, bleaching and deodorizing.
One of the purposes of the chilling operation ls to enable removal from the neutralized oil of the small traces of caustic liquor that remain entrained in the oil. These amounts of caustic are extremely small and cannot be removed readily by ltration of the oil. We have found however, that if the neutralized oil is chilled, these impurities will be thrown out of solution and can then be removed by filtration if small amounts of filter cel or diatomaceous earth are added. This method of removal we have found is more effective than the method heretofore proposed, of washing lthe neutralized oil with hot water. The chilling of the neutralized pil to eect separation from the traces of caustic can be effected by any suitable means such as for example, by a pipe heat interchanger through which the oil is caused to pass, and its temperature reduced to below about 60v F. The filter aid with adsorbed impurities can be removed from the neutralized oil by means of a filter -press or a hollow barreltype of centrifuge commonly used for removing -small amounts of solid sludges continuously.
'I'he final steps of decolorizing, drying. deodorizing, etc. may becarried out according to any of `the conventional; procedures well known in this field.
As a specific, but non-limiting example of the process of our invention generally described above, We have treated 500 pounds of crude oil having a 1.7% content of free fatty acid content, with 12.3 pounds of 17 B. caustic soda to effect the desired neutralization of the free fatty acids. During this treatment the oil and caustic mixture was heated to about 125 F. for a period of about one hour. As a result of this treatment the usual break" occurred and the appliedheating was then removed. During this treatment the oil and caustic mixture was agitated.4 After centrifuging the thus treated oil to separate the soap stock from the neutralized oil the neutralized oil was then chilled to about 60 F. and passed into a mixing tank where approximately one pound of filter cel was added, and the neutralized oil finally separated by filter pressing.
The neutralized loil resulting from the above described process of our invention has a free fatty acid content of less than 0.008%. This percentage shows an advantage over the oil prepared by the recently proposed quick, continuous processes, which ranges from about 0.015% to 0.04%. While this decrease in free fatty acid content appears to be small, in practice, it represents the difference between a commercially satisfactory and other words, the trade has demanded an oil having a free fatty acid content of less than that normally contained in the product resulting from the quick, continuous type of process, namely about 0.04% or slightly less. In addition to obtaining a product of better quality the process of our invention provides as good or better yields than those obtained in the quick, continuous processes. For example, the neutral oil contained in the foots produced in our process generally runs from 15 to 25% of the total fatty acids, which is comparatively small and accordingly effects a substantial increase in the yield of the finally refined oil.
The process of our invention, by using a smaller excess of alkali and compensating for this reduction by increasing to a limited extent the time of reaction of the alkali and crude oil, effects a substantial reduction in the refining loss. Our process produces an improved oil of relatively low fatty acid content and obtains yields of refined oil equal to or slightly better than the quick refining process. In addition to the improvements the process effects a substantial saving in the amount and cost of alkali used as illustrated by the following:
For a crude oil of an acidity of 1.4% the theoretical amount of alkali as sodium hydroxide necessary to neutralize this free acidity is equal to one-seventh times the free acid or .2 pound sodium hydroxide per pounds of oil. In our proposed process we use a maximum of 40% excess which for this oil would mean a maximum excess of .08 pound or a total of .28 pound, which includes the 40% excess. The same crude oil of 1.4% acidity refined by the quick continuous reunsatisfactory product. In y ing said neutralized oil to remove the soap stock tralize the free fatty acid. Thus, by comparison, it is apparent that our 15% to 40% excess alkali results in a considerable saving of alkali and thereby materially reduces the refining cost.
Various modifications and changes may be made in our process as described hereinbefore without departing from the scope of our invention.
We claim:
1. The process of refining crude corn oil comprising treating said oil with sodium ferrocyanide to effect partial neutralization of the free Vfatty acid content of said oil, adding filter-aid and filtering to remove the 'coagulated material, neutralizing the partially refined oil in batches by the addition of approximately 15% to 40% excess alkali while heating to a temperature of approximately 125 F. to 140 F. for about 30 to 60 min-4 utes, combining the neutralized oil from said batches, centrifuging said neutralized oil to remove the soap stock formed by neutralization of the free fatty acids, chilling the neutralized oil to separate out of solution remaining small traces of alkali and water, adding filter-aid and ltering.
2. The process of refining crude corn oil comprising treating said oil with about 0.2% soformed by neutralization of the free fatty acids.
3. A process of reflningcorn oil comprising adding to said oil about 2% of a 10% solution of sodium ferrocyanide, maintaining said ferrocyanide in contact with said oil until a coagulum is formed, filtering to remove said coagulum thereby producing a partially refined corn oil, separating said partially refined corn oil into batches, treating each of said batches of oil at a temperature of approximately 125 F. to 140 F. for about 30 to 60 minutes with a 15% to 40% excess of alkali to effect neutralization of the remaining free fatty acid content of said oil, centrifuging the neutralized oil mixture to effect separation of the neutralized oil from the soap stock form ed by the reaction between said alkali and the free fatty acids in said oil, chilling,
l bleaching and deodorizing said neutralized oil.
.4. In the refining of vegetable oil'containing free fatty acids, thelmethod which comprises treating the oil with sodium ferrocyanide, to decrease the acidity, then treating the oil with an alkali to neutralize additional acid and form soap, and separating the soap from the remaining oil. 5. In the refining of vegetable oil containing lecithin and free fatty acids, the method which comprises treating the oil with an aqueous solution of sodium ferrocyanide to cause coagulation of lecithin and a part of the fatty acids, separating the coagulated materials from the oil, treating the remaining oil with alkali to neutralize additional acid and form soap. and separating the soap from the alkali-treated oil.
RAYMOND E. DALY. JAMES F. WALSH.