US2417329A - Method of refining crude wool grease - Google Patents

Description

E. SNYDER METHOD OF REFINING CRUDE WOOL GREASE Filed Jan. 27, 1944 are H, 1947' TIIIIIL N\.

ATTORNEYS MTR?? M/\ uw R Patented Mar. 1l, '1947 METHGD F REFINING CR'UDE WOOL GREASE Eugene Snyder, Philadelphia, Pa., assigner to American Chemical Paint Company, Ambler, Pa., a corporation of Delaware Application January 27, 1944, Serial No. 519,933

26 Claims.

This invention relates to an improved method of refining crude wool grease and has for its primary object the provision of a simple and economical method for producing either hydrous or anhydrous lanolin of high grades, but before describing the invention in detail or reciting its objects more specifically it is desired to refer briefly to certain of the present prior art practices in the production of crude Wool grease because it is believed that the nature of the invention will be more fully understood and appreciated with these facts in mind.

Probably the most common method of removing grease from raw Wool is by washing the wool in solutions containing soap and soda ash, which solutions then contain emulsiied wool grease, dirt, salts, soaps from the neutralization of free fatty acid in the wool, pollen, proteins from various sources, etc. The crude grease is then separated from such liquors by settling, centrifuging or both, and enters the market as crude wool grease. It is sometimes sold as hydrous crude wool grease which is a cream still containing approximately 15 to 40% of water as well as other impurities associated with the scouring solution emulsied therein. It may be recentrifuged to a Water content of from 1 to 3% and sold as "dry crude wool grease. In either case, this crude material must be refined before it can be used for pharmaceutical or cosmetic purposes, and even for less critical uses it often needs to be at least partially purified before it is suiiiciently free of objectionable odor, grit, soap, etc.

There are, however, two other rather common ways of recovering crude wool grease. One is to scour the wool with a solvent and to recover the grease by distilling oi the solvent from the ltered solution. This yields a dry crude grease. The other method recovers not only wool grease but also all the fatty acid from the soap in the scouring liquor. It consists in breaking the grease emulsion in the scouring liquor by acidulating it-generally with sulphuric acidwhereupon there separates a foul-smelling upper layer sold in England as Yorkshire grease. It has also been sold as degras, although the latter name is used to denote other products, notably a product which contains the free fatty acids recovered from the soaps associated with crude wool grease together with some of the' unsaponied grease not recovered in the separation of the grease.

My improved process is most easily applied tc a creamed emulsion of grease, containing Water soap, dirt, coloring matter, proteins and othei impurities known as crude hydrous Wool grease although it may also be applied to other type: of impure crude wool grease such as dry crude grease and even, indeed, to acid cracked woo grease or Yorkshire grease, although, in this latter case, it lacks one of the main advantages of my invention as will more fully appear hereinafter.

With the foregoing in mind my invention has among others, the following objectives:

(1) To rene crude Wool grease without using alcohol or any other organic solvent in the rening process which feature of the invention obviates the provision of stills or other equipment ordinarily employed in the recovery of the solven used, and (2) to provide a method of refining crude wool grease by means of which it is possible to avoid subjecting the grease to be refine( to acid or to acidied Water, in fact, to avoic subjecting the grease to a pI-I below 7 at any stag| of the rening operation. This is an importan advantage of my improved process because, i1 my experience, I have found that the color an: odor of the rened grease is adversely affecte( by acidulation at any stage of the refining operar tion even though the grease may later be treate( so as to contain no free fatty or other acid.

In connection with the following detailed de` scription of my improved invention, attention i directed to the accompanying drawing whereii Figure 1 is a diagrammatic representation oi th steps pursued and the preferred apparatus em ployed in carrying out the process as applied t1 hydrous crude wool grease, and Figure 2 illus trates certain details of the construction of on of the washing towers employed in the process I Wish it to be understood, however, that the ap paratus shown is merely illustrative because othe types of equipment might Well be employed i1 carrying out the steps of the process.

In carrying out my process I rst emulsify th melted crude grease in water solution containin soap. Hydrous crudes may contain enougl soap to produce this emulsion merely upon heat ing and stirring the melted crude, but with th so-called dry orudes, in addition to the water needed, it may be necessary to add some soap in order to produce a good emulsion.

Next I add to the emulsion alkaline chemicals, preferably such as contain an alkali silicate. Insofar as certain basic advantages of my improved process are concerned, this addition may not always be necessary but it assures the removal of free fatty acid contained in the crude grease. Such free fatty acid may be present even in crude which is alkaline in reaction due to hydrolysis of soap. The alkali also aids in dissolving protein impurities and in suspending solid dirt in the aqueous phase which is separated in accordance with the step to be described below.

If it is desired to recover a very light-colored grease, hydrogen peroxide or a per-salt yielding hydrogen peroxide in aqueous solution, such as sodium perborate o1l sodium percarbonate, is added to the emulsion and if such bleaching agents are used it is well to keep the mixture very hot, preferably near the boiling point, until the peroxide in the water is decomposed as indicated by the cessation of gas evolution. Otherwise, gas bubbles adhering to solid impurities may prevent the latter from passing out of the grease layer into the water layer as in the next step.

At this point I add to the mixture a relatively small amount of a water-soluble sulphonated xed oil such as sulphonated castor oil, sulphonated neats-foot oil, sulphonated rape seed oil, sulphonated corn oil, sulphonated soya bean oil, or other sulphonated animal or vegetable oil commonly available commercially as such. Normally these are substantially neutralized materials and do not lower the pH of the mixture below '7.0 which is important in attaining the objectives of my invention as described above. This addition causes a rapid separation of clear grease on top of the mass while the water solution settles simultaneously and rapidly to the bottom carrying with it the soap, the solid dirt and the water-soluble sulphonated oil. The phenomenon following the addition of the sulphonated oil is extremely striking and, insofar as I am aware, entirely novel in the refining of grease and much of the success of my improved process depends to a large extent on this rapid clean separation of grease on the one hand from a water solution or suspension of the impurities on the other hand. The separation is made so thorough, in fact, as to make possible countercurrent water washing of the grease in accordance with the following step. If the separation is not thorough losses of grease in the waste wash water may become serious so that the process is uneconomical.

The grease layer is now separated from the water layer and is washed in hot water in one or more washing tanks in which, preferably, the wash water flows in counter-current to the grease. In this way the last traces of water-soluble impurities such as soap, alkali, etc. are removed and the grease separated from the mass at the top of the last washing tank where it appears as a clear neutral, light-colored material which, except for a little extra moisture, is of U. S. P. lanolin grade.

The grease may now be separated from any remaining wash water and dehydrated if a dry product is required. This is best accomplished by passing the grease, together with some water, if desired, through a centrifugal separator by means of which the grease can readily be brought to a water content of 0.2% or less.

With the foregoing procedure the grease is now generally marketable as U. S. P. lanolin. However, for some purposes, especially for the cosmetic industry, a further improvement in the quality of the refined grease may be desirable in which event either or both of two further steps may be included as follows. Add to the grease .a small amount of bleaching earth or decolorizing carbon or both, stir hot for a short time, and pass through a filter press. Or pass the hot grease, either filtered or unfiltered, through a chamber in which a partial vacuum is maintained, which treatment serves to remove traces of volatile odoriferous impurities along with traces of moisture. This step may be assisted by the introduction of live steam, air or inert gas beneath the surface of the grease While it is under vacuum. The apparatus for use in this step need not be elaborate. If no steam or gas is bubbled through it the grease should be spread out into thin layers, as by allowing it to trickle over a series of inclined trays while it is under vacuum, soV that the time of retention in the deaerating chamber may be short. Another method of assuring quick removal of volatile impurities from the grease is to introduce it into the vacuum chamber as a spray. After removal from the de-aerating chamber the refining operation is concluded and the grease may be run directly into drums, barrels, or other tight containers for shipment.

With the foregoing outline of the essential features of my improved process in mind, I will now describe in detail the accompanying drawing in order to more fully illustrate the steps of the process. The crude grease is received in steel drums 1 which are inverted over the steam-pipe grille 2 at the top of the melting tank 3 in which the crude grease is kept molten and hot by steam coils 4.

After melting, the hot crude grease, containing from 20 to 40% moisture, is transferred to the processing tank 6 by means of a blow case 5, tank 6 being equipped with steam heating coils 'I and a good mechanical stirrer 8. From tanks 9 or I0, or both, there is then added an appropriate material or mixture which contains, in soluble form,

Pounds Silica, (SiOz) 0.77 Sodium oxide (NazO) 0.40

for every lbs. of anhydrous crude grease present.

The exact quantity of the above alkaline mixture used as well as its SiO2INa2O ratio are not critical and may be varied considerably without greatly affecting the behavior of the process. According to the grade of crude grease in process the sodium oxide added may be varied from 0.3 to 1.0 lb. and the silica from 0.5 to 2.0 lbs. per 100 lbs. of dry crude.

This material may be added in the form of an admixture of low-alkali silicate and high-alkali silicate, as an admixture of low-alkali silicate with caustic soda, or in any other convenient form, as long as suiiioient of the equivalent NazO or equivalent alkali oxide and S102 are present.

Other alkali may be added instead of or in partial replacement of the sodium silicate just referred to. Mixtures of more or less equivalent alkalinity compounded with soda ash, trisodium phosphate, borax, etc. can be used. However.

the emulsion formed with the grease is most easily and quickly broken by addition of the sulphonated oil which follows when the alkali used is a silicate, as described. Moreover, the silicate alkali causes better deflocculation of solid impurities such as dirt, lime soap, etc., which are present in the crude grease than do other alkaline mixtures. Thus these impurities pass more quickly and easily into dispersion in the lower aqueous layer on the breaking of the emulsion described later.

Due to the action of soap present in the crude grease or formed by neutralization of the free fatty acids in the crude grease by the added alkali, the mass, on stirring, forms a uniform white emulsion. To bleach the grease, to kill bacteria, and to destroy odors, there is now added, from tank I I, for each 100 lbs. of dry crude grease, from l to 3 lbs. of 30% hydrogen peroxide, for example, or an equivalent quantity of a hydrogen peroxide solution of different strengh, or of sodium perborate, sodium percarbonate, etc.

The mass is now stirred while being kept hot, preferably at 190 F. to 210 F., until all the peroxide has been destroyed as indicated by the cessation of gas evolution.

From l to 6 lbs., for example, of sulphonated castor oil for each 100 lbs. of dry crude grease, are now added from tank I2. When sumcient sulphonated oil has been stirred in, there occurs, on stopping the stirrer, a rapid separation of clear grease on top of the mass. Simultaneously, a dark colored aqueous solution of soap, alkali, excess sulphonated oil and other water-soluble matter in which is suspended dirt and other insoluble matter, rapidly accumulates at the bottom of the mass. Ii suicient sulphonated oil has been added, a quite sharp separation between clear grease and dirty water occurs and is finished within from 1 to 5 hours.

The separated grease layer is removed through skimmer I3, and passed by pump I4 into the bottom of washing tower I5. From the top of I5, it passes via skimmer 20, to the bottom of the second washing tower I6; and sequentially, via skimmer 2|, to the bottom of the third washing tower I1, as shown.

Fresh hot water enters the bottom of the third washing tower I1 at 25, leaves I1 at the lower side via pump 24, passes into the bottom of tower I6, leaves l5 via pump 23, enters I5 at the bottom, and flows to waste from the lower side of l5 at 26.

Details of the construction of one of the identical towers I3 are shown in Figure 2. It is equipped with heating coils I8 to maintain the grease and water at from l70-200 F. In addition, the tower contains a series of nesting screens 21 tting into each other and into the rings 28, welded to the tower, as shown.

Water and grease enter at the bottom at 30A as shown and rise inside the cylinder formed by the nesting screens 29. The grease is broken into droplets by passing through the screens, and is thus brought into intimate contact with the water in the tower. The water passes upward with the grease, through 21, and then flows over the top of the upper screen ring of 21 and down between the side of the tower and the outside of screens 21 to the water outlet to pump 23.

The grease oats upward and collects at the top of the tower whence it is withdrawn by skimmer 2 I.

By passage through the series of wash towers the grease is thus repeatedly washed while broken up into droplets. Thus the grease collected by skimmer 22 of the third wash tower in which i has been brought into contact with fresh cleai water is practically free of all impurities excep entrained water.

The water is completely separated by centrifugl 30 into which the wet grease is passed at a regu lated rate by pump 3 I The water discharged fron the centrifuge enters receiver 32 from which i is returned to the bottom of the rst washin; tower I5.

The dehydrated pure grease enters receiver 34 from whence pump 35 carries it either to drun 36 for storage and shipment, or to filter tank 31 if further purification is to be undertaken.

In tank 31 which is equipped with mechanica stirrer 38, the grease is admixed with bleachin; solids such as decolorizing carbon, bleaching clay or both, as an example, approximately 2.5% eac] of clay and carbon. The mixture is stirred whili being kept hot by steam coils 39 for a short timi and is then passed via pump 40 through lte press 4l.

The effluent from 4I enters receiver 42 fron whence it is drawn, by the vacuum produced b: vacuum pump 45, into de-aerator 44. On its wa; to 44, it is brought to at least 200 F. by passagi through steam heater 43.

The ltered, de-aerated grease collects in th bottom of de-aerator 44, whence it is drawn b; pump 46 into shipping drums 41.

If it 'be desired to recover the fatty acids fron the soaps associated with the crude grease, th aqueous layer remaining in processing tank E after withdrawal of the grease layer, is withdrawl via pipe 65 to tank 48 where it is treated wit] sufficient dilute sulphuric acid from tank 50 ti liberate the free fatty acid from the soap, whil stirring with mechanical stirrer 49. The quantit; of sulphuric acid used is not critical and depend upon the amount of soap and alkali present. I1 any case, enough acid should be added to rende the liquid in 48 acid-say, to a pH of 4 or les: The liquid is kept hot by steam coils 54.

The free fatty acid rapidly rises to the top o the tank on stopping the stirrer 49. If desirec' the crude fatty acid (degras) which contain traces of unrecovered wool grease, etc., may b purified by passage through an abbreviated wash ing system similar to that used for purifying th separated wool grease.

This is shown in Figure 1 where 5I is a skimmel 52 a degras pump, 53 a washing tower similar t I5, I6 and I1, 54 another skimmer, 55 anothe degras pump` 56 a centrifuge, 58 a degras receiv er, 59 a final degras pump and 60 a shipping o storage drum.

Water separated in the centrifuge 56 enters re ceiver 51. Pump 6I forces this water into the bot tom of washing tower 53 at which point fresl water also enters through 62. The waste wate from the tower flows to waste at B3.

Degras being a relatively cheap material, i does not generally pay to rene it further.

Although I have described my invention as car ried out in a particular kind and design of equip ment, it will be understood that this apparatu has been described in detail only for purposes c illustration and to make the description of my im proved process more intelligible. Many varia tions in equipment and technique will sugges themselves to those skilled in the art and I do nc desire to be limited in process details or appa ratus except as indicated in the appended claim'` I claim: 1. In the rening of crude wool grease tlf.

process which includes emulsifying the grease by agitating and heating it with water,an`d soap to a temperature above its melting point, adding to the emulsion a relatively small amount of a water-soluble, substantially neutral, sulphonated fixed oil, allowing the mass to Isubside to form a water layer and a supernatant grease layer, and then separating the grease layer from the water layer.

2. The process of claim lffin Iwhich the separated grease is washed with hot water.

3. The process of claim ,lain which the separated grease is washed with hot water and then subjected to the effects of a vacuum while still hot.

4. The process of claim lf'which includes also the addition to the emulsion of a relatively small quantity of a silicate alkali prior to the addition of the sulphonated oil.

5. The process of claim lfwhich includes also the addition to the emulsion of a relatively small quantity of a silicate alkali prior to the addition of the sulphonated oil and wherein the separated grease is washed with hot water.

6. The process of claim lywhich includes also the addition to the emulsion of a relatively small quantity of a silicate alkali prior to the addition of the sulphonated oil and wherein the separated grease is washed with hot water and nally subjected to the effects of a vacuum while still hot.

'7. In the reiining of crude wool grease the process which includes emulsifying the grease by agitating and heating it with water and soap to a temperature above its melting/point, admixing with the emulsion a relatively small quantity of a silicate alkali, admiXing also a relatively small quantity of a substance chosen from the class consisting of hydrogen peroxide and per-salts which liberate hydrogen peroxide when dissolved in water, thereafter adding a relatively small quantity of a water-soluble, substantially neutral, sulphonated fixed oil, allowing the mass to subside to form a water layer and a supernatant grease layer, and then separating the grease layer from the water layer.

8. The process of claim 'it in which the separated grease is washed with hot water.

9. The process of claim "in which the separated grease is washed with hot water and then subjected to the effects of a vacuum while still hot.

10. In the refining of crude wool grease the process which includes emulsifying the, grease by agitating and heating it with waterand soap to a temperature above its melting poi `t, admix- 'ing with the emulsion a relatively small quantity of a silicate alkali, adding a relatively small quan- `:ity of a sulphonated, substantially neutral, xed oil, allowing the mass to subside to form a water layer and a supernatant grease layer, separating the grease layer from the water layer, passing the grease layer through a plurality of washing towers in which it is subjected to intimate contact with hot water, centrifuging the washed grease, and finally subjecting the centrifuged grease to the effects of a vacuum while still hot.

11. In a process of recovering wool grease and :legras from crude wool grease the steps wh h consist in heating the grease above its inglatlng point while it is in the form of an ernul ion with water containing soap, adding to the emulsion a relatively small amount of a wat r-soluble sulphonated, substantially neutral, iixd\oil, allowing the grease to separate from a water` layar containing the bulk of the soluble and insolu- 8 ble impurities and washing the separated grease with hot water; separately acidulating the water layer separated from the emulsion, and removing the degras which separates from the acidulated water layer.

12. The process of claim f1 in which the fixed oil is sulphonated castor oil.

13. The process of claim 1 in which the xed oil is sulphonated castor oil and in which the separated grease is washed with hot water.

14. The process of claim; in which the xed oil is sulphonated castor oil and which also includes the addition to the emulsion of a relatively small quantity of a silicate alkali prior to the addition of the sulphonated castor oil.

15. The process of claim [1 in which the iixed oil is sulphonated castor oil and which also includes the addition to the emulsion of a relatively small quantity of a silicate alkali prior to the addition of the sulphonated castor oil and wherein the separated grease is washed with hot water.

16. The process of claim lain which the fixed oil is sulphonated castor oil and which also includes the addition t0 the emulsion of a relatively small quantity of a silicate alkali prior to the addition of the sulphonated castor oil and wherein the separated grease is washed with hot water and iinally subjected to the effects of a vacuum while still hot.

17. The process of claim/7f in which the Xed oil is sulphonated castor oil.

18. The process of claim ,'l'i'in which the fixed oil is sulphonated castor oil and in which the separated grease is washed with hot water.

19. The process of claim Vin which the fixed oil is sulphonated castor oil and in which the separated grease is washed with hot water and then subjected to the effects of a vacuum while still hot.

20. The process of claim 10 in which the xed oil is sulphonated castor oil.

21. The process of claim lfl in which the fixed oil is sulphonated castor oil.

22. In the rening of crude wool grease the process which includes emulsifying the grease by agitating and heating it with water and soap to a temperature above its melting point, admixing with the emulsion a relatively small quantity of a silicate al li, adding a relatively small quantity of a sulfo ated, substantially neutral, fixed oil, allowing the mass to subside to form a water layer and a supernatant grease layer, separating the grease layer from the water layer and washing the separated grease with hot water, the silicate alkali containing alkali oxide equivalent to 0.3 to 1.0 lb. of Na2O and containing silica in an amount of from 0.5 to 2.0 lbs., each per lbs. of dry crude grease in process.

23. The process of claim Z2 wherein the washed grease is subjected to the eiiects of a Vacuum while still hot.

24. The process of claimlin which the quantity of hydrogen peroxide or hydrogen-peroXide-liberating per-salt is equivalent to from 1 to 3 lbs. of 30% hydrogen peroxide per 100 lbs. of dry crude grease in process.

25. The process of claim in which the separ- 26. The process of claim ated grease is Washed with 9 10 subjected to the effects of a, vacuum while still m q hot and in which the quantity of hydrogen per- UNITEISTATES PA TS D t oxide or hydrogen-peroxide-liberating per-salt is Nlusgbgerv ame age equivalent to from 1 to 3 lbs. of 30% hydrogen 8 1 Mertens Apr' 1 I 1932 271,192 Broun Jan. 23, 1883 peloxide per 100 lbs of dry crude grease 1n process. 5 2,221,559 Scheuer NOV. 12J 1940 1,610,854 Fowler Dec. 14, 1926 EUGENE SNYDER 1,169,154 Holbrook Jan. 25, 1916 REFERENCES CITED OTHER REFERENCES The following references are of record in the 10 Burton, Sulphated Oils and Allied Products, le of this patent: page 17, Chemical Publishing Co., Inc., N. Y. 1940.

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