US1968252A - Process for refining vegetable and animal oils and fats - Google Patents

Description

Patented July 31, 1934 I I 1 9 8 252,

PROCESS FOR "REFINING VEGETABLE AND ANIMAL OILS AND FATS Wilhelm Gensecke, Gonzenheim, near Frankforton-the-Main, Germany, assignor to American Lurgi Corporation, New'York, N. Y., a corporation of New York No Drawing. Application January 9, 1933, Serial No. 650,946. In Germany November 25, 1932 1- Claim. (01. iii-12) This invention relates to a process for refining The turbid layer containing the mucines and vegetable andanimal oils and fats, and more parother precipitated impurities was separated from t cularly to that stage in the refining of the said the oil by. drawing off said layer from the vessel o ls or fats which is concerned with the separabymeans of an outlet device provided at the lowt on of the impurities-hereinafter termed muestpoint of the vessel. In order to eliminate the cines or phosphatidesin colloidal solution in the final traces of precipitant (e. g. acid) from the oil, crude oil, and of the fatty acids. the latter had then to be repeatedly washed with These mucines, phosphatides or the like, 001- hot water. loidally dissolved in the crude oil are separated For the purpose of neutralization, the oil, freed out during the separation of the free fatty acids from the mucines and the like, was next pumped by saponification with alkali or other neutralizing into the actual refining apparatus, where the agents. In that operation the mucines become fatty acid was separated from the oil-by saponifienveloped in the flakes of the fatty-acid soap and cation with alkali. Although the resulting oils greatly increase the bulk of the latter. These were neutral and entirely free from mucines and 15 voluminous soap flakes only bed together loosely, like impurities, and a better yield of oil was obon deposition, and therefore occlude. a good deal tained than by merely refining with alkali, withof neutral oil. out any special pre-refining, the quality of the In order to lessen this loss of neutral oil during oils was mostly inferior to those treated 'solely the refining process, certain so-called pre-refining with alkali, that is to Say, Without D fi n 20 processes have been devised with the object of with acid or saline electr y I depositing and removing the colloidally dissolved According t t process of the present invenmucines before proceeding to saponify the fatty t the refining o Vegetable el'iahimel 011$ acids. The known methods of such pre-refining fats is f d y means of the o fi n p consist in treating the oils or fats with aqueous ess known per with saline electrolyte l s,

2 solutions, for example of organic and inorganic and by neutralizing the fatty acids with alkali. 30 acids, saline electrolytes, tanning agents and the In C a ever, to the usualmpthod o p like. The pre-refining by these known methods cedure, the pre-refining and neutralization are was performed in special apparatus, adapted, f d in a Single l Operation, inasmuch both in respect of material and shape, to the puras the alkali required for neutralizing first the 30 pose in view, In th first l e, the 011 or fat, t fatty acids and secondly those acids still present be treated was energetically stirred, in a 1, on account of the pre-treatment with acid-saline with the medium (reagent) intended t precipi-' electrolytes, is added to the oil immediately after tate the mucines, mechanical stirrersbeing usualthe action of the saline electrolyte solution or of ly employed, though air was also occasionally inthe aqueous solution of saline electrolytes and 35 troduced. After the precipitant had operated for ac d whereby the Various. mucines are D p a sufiicient time, the stirrers wereput out of actated. Consequently the precipitated mucines tion, and the contents of the vessel left torestpand the like t he w the uheensumed portion During this stage the'separated impurities gradof the saline electrolyte solution and the saline ually settled down to the bottom of the vessel, in solution derived from the neutralization of the 40 t form of a separate layer of turbid material excess of acidin cases where an excess of prewhich, when an acid had been employed as preeipitant. used-remain in the. Oil d the cipitant,'also contained such acid. A source of impurities, e SS 0f precipitating agent and difiiculty in this treatment was caused by the cir the soap stock formed by the neutralization of cumstance that, on the one'hand, a considerable t fatty acid a p e p together o the 45 time is advantageous for obtaining a satisfactory O ldeposition of the impurities from the oil, whereas, The present invention offers the following adon the other hand, the protracted contact with vantages in contradistinction with the known the precipitantsuch as acid or dissolved saline methods of working. r

electrolyteimpairs the quality of the ,oil. If the The mucines colloidally dissolved in the crude 50 temperature beraised, in order to accelerate the oil and other impuritiesare precipitated in floccudeposition of the impurities, thismeasure .also lent form by theprecipitating agent, namely a has an injurious effect on'the quaiity'of the oil. saline electrolytesolutlon or mixtures of various The restriction of this pre-refining to isolated insaline electrolyte'solutions oracid saline electrostances in practiceis explained by the aforesaid .lyte solutions. The flakes'thus produced float in diffleulty! the oil which is'free from mucine. In this con- .110

nection the acid saline electrolyte solution may either be added as such to the oil or fat to be treated, or the constituents of the electrolyte mixture can be ,added to the oil in succession, that is to say the acid is first added and then the saline electrolyte solution or vice versa. Immediately on precipitation of the colloidally dissolved mucine, alkali solution or any other suitable neutralizing agent is added to the oil. When employing an acid saline electrolyte solution as the precipitating agent any excess of acid that may be present is neutralized with the formation of the corresponding salt as is also the free fatty acid present. Flakes of soap are formed which include a small quantity only of neutral oil. The bodies precipitated out by the saline electrolyte solution or acid saline electrolyte solution, that is to say heavy flakes of mucine and any excess of saline electrolyte solution employed effect a rapid and eflicient separation of the soap flakes from the oil and when the stirrer is stopped a thick layer of soap and mucine flakes is quickly formed, which includes considerably less neutral oil than the soap stock which is obtained by known meth-.

Ode of neutralization from crude oil. The soap stock settles down rapidly and an excellent yield of neutral oil free from mucine is obtained having a satisfactory consistency.

The soap stock consisting of soap flakes, entrained neutral oil, saline electrolyte solution and coagulated mucines and the like, can readily be separated into high grade neutral oil and high grade fatty acids by extraction with a solvent with subsequent treatment with acids. By extracting the soap stock with benzene or like oil solvents a solution of neutral oil-and a mixture of soap and solvent is obtained. The oil solvent is distilled off from the neutral oil solution leaving the neutral oil. The extracted mixture of soap and oil solvent is decomposedby inorganic or organic acids into a mixture of fatty acids, solvent and saline solutions, whereupon the solvent autoclave, as is universally employed at present and in which the valuable neutral oil is destroyed, is avoided. The soap stock obtained in the neutralization processes in general employment at the present day contains the mucines and the like precipitated from the oil in quite a different form from that in which these substances. are precipitated according to'the process of the present invention. The mucines and the like were the cause of the difliculties which were encountered during the extraction of oil from soap stock recovered by the known processes.

A-single apparatus only is required for the process of the present invention, so that the prime and running costs are considerably reduced. In the removal of mucine and neutralization, hitherto usually carried out separately, there occurs during the separation of the reflned oil and soap stock, approximately twice the loss of oil as in the case of the process of thepresent invention, in which only one separation is necessary of neutral oil and the deposited layer of mucine and soap. The separation of mucine may also be efiected at a moderate temperature.

Example 1 1000 Kg. of soya bean oil containing 0.5% of free fatty acids are heated to 30 C. in an apparatus provided with stirrers. '7 litres of saturated magnesium sulphate solution are then added, whilst vigorous stirring is continued. The

vat the bottom of the vessel which contains a small quantity only of oil. The supernatant. oil is then decanted off. 1

Example 2 1000 Kg. of earth nut oil are warmed'to a temperature of 28 C. in a vessel provided with stirrers. 8 litres of an acid saline electrolyte solution consisting of 8 volumes of 30% sulphuric acid and five volumes of saturated sodium sulphate solution are then added with further vigorous stirring. The mucines colloidally dissolved in the crude oil are precipitated in a short time in the form of granular flakes which float in the pure oil. A quantity of caustic soda lye of 18 B. is thereupon added with continued stirring suiflcient to neutralize -both the excess mineral acid present in the oil and the free fatty acid also present. Fine grained soap flakes are formed including a small quantity of neutral oil. The oil is then warmed to a temperature, of 55 C. with further stirring and is thereupon left to stand.

asmall quantity only ofoii. The oil is then decanted.

.I claim: Y

A process for removing mucines, phosphatides and the like and fatty acids from vegetable and animal oils and-fats which comprises precipitating the mucines, phosphatidesand the like with saline electrolyte solutions also containingan acid, and neutralizing the fatty acids and any acid derived from the previous treatment with alkali before separating oi! the precipitated impurities, the substances deposited during both stages at treatment being separated jointly by settling from the refined oils 'andfats.

WILHELM GENSECKE.