US3458543A - Method of treating spent wool scouring liquors - Google Patents

Description

United States Patent 3,458,543 METHOD OF TREATING SPENT WOOL SCOURING LIQUORS Milan Koubik and Vaclav Kresta, Prague, and Jiii Valenta, Boskovice, Czechoslovakia, assignors to Mosilana, Narorlni Podnik, Brno, Czechoslovakia No Drawing. Filed Mar. 22, 1966, Ser. No. 536,315 Claims priority, application Czechoslovakia, Mar. 24, 1965, 1,947/65 Int. Cl. Cllb 11/00 US. Cl. 260-4125 Claims ABSTRACT OF THE DISCLOSURE Lanolin is recovered from spent alkaline scouring liqor, preferably after removal by centrifuging of the major portion of its original lanolin content, by mixing spent alkaline scouring liquor having a pH between about 7.5 and 10, and preferably of between 8.0 and 9.5, and being free of solvents for lanolin, with an alcohol having between 6 and 8 carbon atoms per molecule. The alcohol is admixed in an amount greater than that which is soluble in the spent alkaline scouring liquor from which lanolin is to be removed, and equals between 1 and 25%, preferably between 1 and 10% of the volume of the alkaline scouring liquor, whereby the thus-formed mixture will separate into a heavier, aqueous, substantially lanolinfree phase, and a lighter lanolin-containing alcoholic phase from which lanolin may be recovered.

The present invention relates to a method of treating wool scouring liquors and, more particularly, the present invention is concerned with a method of recovering lanolin from alkaline, aqueous scouring liquors which have been used for the washing of raw wool and which broadly consist of an alkaline aqueous solution of soap and/or detergents which is free of solvents for lanolin.

According to the method of the present invention, lanolin is obtained as an important raw material for further processing and simultaneously the disposal of the spent scouring liquor is facilitated due to the removal of lanolin therefrom.

Prior to further processing, the raw or greasy wool must be freed of suint (wool sweat), wool wax (lanolin), dirt and dust. This is conventionally carried out by washing the raw wool in a suitable apparatus, for instance of the type known as Leviathan. Since lanolin is insoluble in water but soluble in some organic solvents, the removal of lanolin from the raw wool may be carried out by two difierent methods, namely either by converting the lanolin into an aqueous emulsion by means of a soap or detergent, or by including suitable solvent in the washing liquid.

Consequently, the methods of washing raw or greasy wool can be divided into two groups, depending on the type of washing agents which are employed.

According to the method which is most frequently used, the raw wool is washed with an alkaline, aqueous liquid containing as the washing agent either a soap or a synthetic detergent or a combination of both.

The other group of methods is concerned with the washing of raw wool with a washing liquid consisting of one or more solvents or with an aqueous soap or detergents-containing, washing liquid to which an organic sol' vent has been added.

Solvents which may be used in connection with the last-mentioned method of washing raw wool include, on the one hand, hydrocarbons such as benzene, hexane and the like and, on the other hand, water-soluble alcohols such as methanol, ethanol and propanol, or partially wa- 3,458,543 Patented July 29, 1969 ter-miscible higher alcohols, for instance butanol or amyl alcohol.

According to both washing methods, the extraneous materials adhering to the wool, such as suint, lanolin and impurities will pass into the washing liquid. It is the advantage of washing with an organic solvent per se, or a mixture of organic solventand water, that the lanolin which is dissolved in the solvent can be quite easily separated by distilling off of the solvent. However, it is a very serious disadvantage of the washing of wool with solvents that the thus washed wool is of considerably poorer quality than similar raw wool which has been washed with an alkaline aqueous soap or detergent-containing solution without the addition of a solvent. Furthermore, lanolin recovered as the distillation residue after distilling off of the solvent is highly contaminated by dissolved material such as wool sweat, detergents and sludge. These disadvantages of the solvent washing method are reflected in the fact that the method generally is still only in an experimental stage although the solvent washing method had been suggested more than ten years ago.

The wool obtained by washing raw wool in an alkaline aqueous liquor containing soap or synthetic detergents is of high quality, however, it is rather difiicult to separate lanolin from the spent washing liquor. Due to the fact that the impurities which are transferred from the wool to the Washing liquid amount to up to one-half of the weight of the raw wool, it is obvious that the spent washing liquid contains a very high concentration of impurities. From an economic point of view, it is important to achieve as complete as possible a separation of lanolin from the spent washing or scouring liquor because the lanolin per se is a valuable raw material and because it is rather difficult to biologically degrade lanolin and, consequently, waste waters containing significant amounts of lanolin are diflicult to dispose of.

It is possible to separate a portion of the lanolin from the spent scouring liquor by mechanical separation, for instance centrifuging. However, even after thus separating a portion of the lanolin, the residual spent scouring liquor still contains relatively large amounts of lanolin in the form of an emulsion which can no longer be mechanically removed. The residual content of lanolin in the spent scouring liquor, after centrifuging of the same, varies considerably, generally within the limits of between 5 and 20 grams of lanolin per liter. While methods for mechanically separating the mechanically separatable lanolin fraction have been highly developed and are conventionally carried out by centrifuging, it appears that up to now no satisfactory method has been found for separating the residual lanolin content of the centrifuged spent scouring liquor.

Methods which were proposed up to now for separating or rendering harmless the residual lanolin of the cen trifuged scouring liquor have not met with substantial success due to the high costs involved or the technical difficulties experienced in carrying out such processes.

Consequently, disposing of spent scouring liquors, which may or may not have been centrifuged, and in any event without removal of the residual lanolin which does not lend itself to removal by centrifugation, causes serious contamination of the body of water into which the spent scouring liquor is released and also considerable losses due to the failure of recovering the residual lanolin of the spent scouring liquor.

The methods which have been suggested for removing lanolin from the spent scouring liquor obtained in the washing of raw wool with an aqueous, soap or synthetic detergents-containing liquid, include the following:

(1) An acid method has been proposed according to which the spent scouring liquor is mixed with such an amount of sulfuric acid that a strong acidic reaction is reached and the thus treated spent scouring liquor is then placed into a sedimentation tank in which the liquor separates into three layers. The uppermost layer is formed of separated wool wax and floating impurities, the lowermost layer is formed of impurities having a higher specific weight than water, and interposed between these two layers is a layer of substantially pure acidified water. This intermediate layer, after neutralization thereof, can be released into a sewer or the like. The relatively heavy sludge of the bottom layer is dried in conventional manner, and the uppermost layer is freed of solid impurities by filtration and thereby the crude Wool wax or lanolin is recovered. However, the thus obtained crude wool wax is of very poor quality and not suitable for further use, due to the fact that it generally contains between 12-18% of free fatty acids and has a very dark color.

One of the undesirable side effects of this method is that carbon dioxide is freed during the acidification of the spent scouring liquor and this causes considerable foaming. Furthermore, it is not possible in this manner to recover lanolin of reasonable purity but only to purify waste waters at relatively high costs.

(2) A flotation method has been proposed, according to which the spent scouring liquor is aerated with finely subdivided air bubbles which carry lanolin along towards the surface of the spent liquor. The thus obtained foam is washed, freed of solid impurities and then the lanolin separated either by centrifuging or in an autoclave at relatively low pressure. However, this method is not reliable, frequently does not give the desired result and thus has not found wide acceptance.

(3) According to another method, it is proposed to first partially evaporate the spent scouring liquor so as to increase the lanolin content thereof to between about 4 and 5% thereby also causing concentration of the alkali content of the scouring liquor. The thus thickened liquor is then heated at a gauge pressure of 3.5 atmoshperes to a temperature of between 143 and 150 C. and allowed to stand for between 1 and 18 hours so as to permit separation of the lanolin. However, the technological and energy requirements of this method are too high so that there is only little chance of its practical application.

(4) A chemical precipitation process has been proposed whereby due to reaction between substances dissolved in the spent scouring liquor such as sodium carbonate, wool sweat salts and the like, and.the added precipitating agent such as calcium hydroxide, calcium chloride, ferrous sulfate and the like, flocculation will occur and the thus formed flake-like particles will carry along the lanolin content of the spent scouring liquor. In order to achieve high effectiveness with respect to the separation of lanolin from the spent scouring liquor, it is necessary to supersaturate the solution with the preciptating agent at a temperature of about 80 C., and thereby a large amount of sludge is formed which has to be dewatered or dried. Furthermore, large amounts of precipitating agents are required, the heat consumption is high and the difiiculties in the removal of the sludge increase the operating cost. In addition, the valuable lanolin which is carried along with the sludge cannot be recovered so that this method results only in a purification of waste waters.

(5) Another method has been described, according to which the lanolin of the spent scouring liquor is to be absorbed in an ion exchanger, particularly on a sulfonated phenolic resin in H-form. The lanolin which is thus taken up is then washed out with a solvent such as a suitable hydrocarbon. The mechanism of the taking up of lanolin by the ion exchanger is as yet not quite clear.

(6) Biological purification of not pretreated, spent scouring liquors, simultaneously with other waste waters, is possible only upon a high degree of dilution of the spent scouring liquor which generally is not possible.

The above review will serve to show that up to now apparently no satisfactory method exists for the recovery of the portion of lanolin which cannot be separated by centrifuging or the like from the spent scouring liquor obtained in the washing of wool with an alkaline aqueous soap or detergent containing medium, and particularly, there does not appear to exist any method whereby this portion of lanolin can be recovered in a sufliciently high yield and in a purity which permits further working up of the same.

It is therefore an object of the present invention to overcome the above-discussed difliculties and disadvantages with respect to the recovery of lanolin from spent scouring liquors obtained in the washing of raw wool with alkaline, aqueous, soap and/or detergents containing washing liquors which are free of solvents for lanolin; and thus, it is also an object of the present invention to free such spent scouring liquors of lanolin and thereby to make the spent liquors more easily disposable.

It is a further object of the present invention to provide a method for the recovery of lanolin from spent alkaline aqueous scouring liquors of the type described above, or for the recovery of the residual lanolin remaining in such spent scouring liquors after centrifuging, which method can be carried out in a Simple and economical manner and will result in the recovery of lanolin of relatively high purity and in a high yield.

Other objects and advantages of the present invention will become apparent from a further reading of the description and of the appended claims.

With the above and other objects in view, the present invention contemplates a method of removing lanolin from spent alkaline scouring liquor obtained by scouring of raw wool with an aqueous, alkaline solution of soap or detergents, comprising the steps of mixing the spent liquor with an alcohol having between six and eight carbon atoms per molecule, the alcohol being admixed in an amount sufficient to cause separation of the thus formed mixture into a heavier, aqueous, substantially lanolin-free phase and a lighter lanolin-containing alcoholic phase, and separating the phases from each other.

According to a preferred embodiment of carrying out the method of the present invention, the scouring liquor which is free of solvents for lanolin may include sodium carbonate and have a pH of between 7.5 and 10, and furthermore, the spent alkaline scouring liquor, prior to mixing with the alcohol is subjected to centrifuging so as to remove a major portion of its original lanolin content therefi'om, and the alcohol which is admixed to the scouring liquor is n-hexanol and is admixed in an amount equal to between about 1.5 and 2.5% of the volume of the thus-formed mixture. The lanolin is then recovered from the thus-formed lanolin-containing alcoholic phase and the simultaneously separated alcohol of the alcoholic phase is recycled and may be admixed to subsequent portions of spent alkaline aqueous scouring liquor for removal of lanolin therefrom.

It will be noted that the present invention is concerned with the recovery of lanolin from spent scouring liquor obtaining the scouring of raw wool with an aqueous, alkaline, soap or synthetic detergent solution which preferably contains sodium carbonate, i.e. an alkaline solution having a pH which generally will be within the range of between 7.5 and 10.0 but most frequently between about 8.0 and 9.5.

The thus-obtained spent scouring liquor will contain substances which had been washed out of the wool such as suint, solid impurities of different specific weight and size, and wool grease, i.e. lanolin and also chemical agents added in order to separate the wool grease from the raw wool, such as washing agents, either soap or anionic or non-ionic detergents, and sodium carbonate. However, the spent scouring liquor will be free of solvents for lanolin.

The amount of suint, and of the chemical agents which are to be added, will depend on the specific technological conditions of the raw wool scouring process. The amount of solidimpurities in the spent scouring liquor will depend on the type of raw wool which is scoured, and on any pretreatment of the spent scouring liquor, i.e. whether or not the same has been subjected to centrifuging and thereby solid impurities and a considerable portion of the lanolin content of the spent scouring liquor have been removed prior to subjecting the same to the process of the present invention.

Generally it is preferred to use aliphatic alcohols with between 6 and 8 carbon atoms per molecule, although it is also possible to carry out the process of the present invention with aromatic alcohols of between 6- and 8 carbon atoms per molecule, however, at a somewhat lower efiiciency. For best results, it is preferred to use n-hexanol as the alcohol which is to be admixed to the spent alkaline scouring liquor. Within a number of carbon atoms of between 6 and 8 in the alcohol molecule, better results appear to be obtained with alcohols containing a lesser number of carbon atoms, such as 6 per molecule than with alcohols containing a larger number of carbon atoms such as :8.

Thus, according to the present invention, the lanolin is recovered from the spent scouring liquor obtained by the washing of raw wool with alkaline aqueous soap and/ or synthetic detergent-containing washing liquors, either directly or after first removing solid impurities and a portion of the lanolin by centrifuging, by admixing a relatively small proportion of an alcohol containing between 6 and 8 carbon atoms per molecule to the spent scouring liquor whereby it will be accomplished that the lanolin which is emulsified and dispersed in the spent scouring liquor will separate into an alcoholic layer. This process can be, and preferably is, carried out without changing the pH of the alkaline, aqueous spent scouring liquor.

After admixture of the alcohol, two separate phases are obtained, either by allowing the mixture to stand and thereby to separate into two phases or by centrifuging, namely an upper layer or phase of lower specific gravity consisting of alcohol, lanolin and possibly a small proportion of water, and a lower layer or phase of higher specific gravity consisting essentially of water and being substantially, but generally not completely, free of lanolin, and also containing the washing agents such as soap or detergents, wool sweat salts and the like as Well as a portion of the alcohol corresponding to its solubility in the aqueous phase. The heavier aqueous phase is then freed of dissolved alcohol by boiling and may either be directly recycled for use in the subsequent washing of raw wool or first subjected to purification. The regenerated alcohol may be recycled and reused for admixture to subsequent portions of spent alkaline aqueous scouring liquor for the purpose of separating lanolin therefrom.

The lanolin which is contained in the alcoholic phase of lower specific gravity is separated from the alcoholic phase by centrifuging at a temperature which should be higher than 40 C. and up to 80 C., or is obtained as distillation residue after steam distillation or direct heat distillation of the alcohol, the latter distillation preferably being carried out under reduced pressure in a manner known to those skilled in the art. The thus-obtained regenerated alcohol may then be reused for admixture to subsequent portions of spent alkaline aqueous scouring liquor. As pointed out above, the separation of lanolin which is present in emulsified condition in the spent alkaline aqueous scouring liquor does not require changing the alkalinity of the spent liquor which generally is within the range of pH 7.5-10.

When scouring raw wool in an alkaline water bath, the alkalinity of which is due to the admixture of sodium carbonate, the pH value of the scouring liquor and thus also of the spent scouring liquor will vary dependent on whether the scouring liquor contains soap or synthetic detergents. If the scouring liquor contains soap, the pH generally will be somewhat higher, such as between 8.5 and 10.0. On the other hand, if synthetic detergents and no soap are incorporated in the scouring liquor, then the pH will be somewhat lower, namely between about 7.5 and 8.5.

Furthermore, the incorporation of sodium carbonate in the scouring liquor is generally desirable and the proportion thereof and thus the alkalinity of the scouring liquor will to some extent depend on the type of raw wool which is to be scoured. Thus, when scouring lower grades of raw wool which contain more degraded grease comprising larger proportions of free fatty acids, the sodium carbonate demand will be higher. It may be noted that the composition of alkaline aqueous scouring liquors containing soap and/or detergent are well known to those skilled in the art and, per se, do not form part of the present invention.

The minimum pH which is desired for the removal of lanolin from the spent scouring liquor in accordance with the present invention will be about 7.5 and since generally sodium carbonate will be one of the constituents of the scouring liquor, the pH of the same always will be at least that high. An excessively high pH value, higher than 10, would not affect the method of the present invention, but would not be desirable because it would lower the quality of the wool which is scoured. Thus, the scouring of the wool by means of an aqueous soap or synthetic detergentcontaining liquor is always carried out in an at least slightly alkaline medium, while the scouring processes which are performed in a neutral medium require the use of solvents for lanolin which solvents are not included in the type of spent scouring liquor which is treated according to the present invention.

Lanolin is only slightly soluble in alcohols having between 6 and 8 carbon atoms per molecule and thus the lanolin in the alcoholic phase obtained as described above it not in dissolved condition. However, the admixture of alcohol to the spent scouring liquor containing either its initial lanolin content or (as generally will be the case) only the residual portion thereof which could not be removed by centrifuging, will cause a change of the polar forces in the spent alkaline aqueous scouring liquor which will cause the emulsified lanolin of the spent scouring liquor to pass in the form of a dispersion of lanolin into the alcoholic phase, from which the dispersed lanolin can be separated by centrifuging or distillation.

Thus, the lighter phase, i.e. the lanolin in alcohol dispersion, may be split by centrifuging whereby the relatively small difference between the specific weights of lanolin and of the above-described alcohols will require a relatively powerful centrifugal field and a relatively long period of centrifugation. The temperature during centrifuging should exceed 40 C., in order to be safely above the solidification point of lanolin which is at 39 C. On the other hand, it is preferred to carry out the centrifugal separation of lanolin at temperatures which do not exceed C. without, however, limiting the centrifugal separation of lanolin in the context of the present invention to such upper temperature of 80 C. which generally is chosen just for reasons for technological convenience.

The separation of lanolin from the alcoholic phase by distillation at atmospheric pressure or under a partial vacuum, as well as the separation of the dissolved portion of the alcohol from the aqueous phase, or mixtures thereof with other non-volatile substances such as lanolin by steam-stripping, is well known to those skilled in the art. Generally, distillation may be used as the method for separating the alcohol from the lanolin of the alcoholic phase, whereby care should be taken only not to overheat the lanolin, i.e. not to expose the lanolin to a temperature above C., since at this temperature and higher temperatures the quality of the lanolin might suffer. Since the boiling point of the alcohols containing between 6 and 8 carbon atoms per molecule is higher than 120 C., it is therefore desirable, in fact practically necessary, to carry out the distillation under a partial vacuum.

The method of steam-stripping will be useful only for the separation of some of the mentioned alcohols, such as aliphatic alcohols with between 6 and 8 carbon atoms per molecule, from the lanolin-containing alcoholic phase. In

this case, the alcohols will be separated as an azeotropic mixture having a boiling point below 100 C.

In order to achieve separation of the maximum amount of lanolin from the spent alkaline aqueous scouring liquor, it is important to admix thereto a suitable proportion of the alcohol. The amount of alcohol admixed to the spent scouring liquor must be greater than that corresponding to the solubility of the respective alcohol in water. However, in order to achieve optimum results, it is practical and sufficient to operate with only a slight excess of alcohol above the amount thereof which will be dissolved in the aqueous scouring liquor. Depending on the amount of lanolin in the spent scouring liquor which is to be treated, which amount depends on the type of raw wool which has been scoured and on whether or not and to what extent dispersed lanolin has been removed from the spent scouring liquor by centrifuging prior to carrying out the process of the present invention, the required addition of alcohol will be equal to between about 1 and 10% of the volume of scouring liquor which is to be treated, and the optimum proportion will be between 1.5 and 2.5% by volume thereof. Within the limits of between about 1 and 10% by volume of alcohol, the effectiveness of the lanolin separation remains practically unchanged so that a slight excess of alcohol has no disadvantageous results.

If the alcohol is added in an amount higher than 10% of the volume of the spent scouring liquor, then the effectiveness of the lanolin separation will be reduced, and if the addition of alcohol reaches about 25% by volume or more of the scouring liquor, lanolin will no longer be separated but a new type of lanolin emulsion will be formed. On the other hand, it has also been found that introduction of alcohol in a proportion of less than about 1% of the volume of the spent scouring liquor will not cause the desired separation of lanolin therefrom.

Suitable alcohols which may be admixed to the spent alkaline aqueous scouring liquor for the purpose of separatink lanolin therefrom, in accordance with the present invention, include the following hydrocarbyl alcohols: nhexanol, secondary hexanol, teritiary hexanol, cyclohexanol, benzyl alcohol, n-heptanol, n-octanol, secondary octanol, tertiary octanol, iso-octanol, or mixtures of the same. Of the alcohols with between 6 and 8 carbon atoms in the molecule which are used according to the present invention, the best effect is achieved with aliphatic hexanols. If the alcohols with between 6 and 8 carbon atoms per molecule are replaced with alcohols having between 1 and carbon atoms per molecule or alcohols having 9 or more carbon atoms per molecule, it is not possible to destroy the lanolin emulsion in the spent scouring liquor without changing the pH of the spent scouring liquor, and thus, it is not possible in the simple and effective manner of the present invention to form an alcoholic phase having dispersed therein the lanolin which prior thereto has formed an emulsion in the spent scouring liquor.

Upon the addition of, for instance, n-hexanol to the spent alkaline aqueous scouring liquor, it will sufiice to simply permit the mixture to rest or to subject the same to centrifuging, in order to obtain two separate phases, namely an upper more viscous phase of lower-specific gravity consisting of lanolin and the excess amount of solvent beyond the amount thereof which has been dissolved in the aqueous phase. This upper lanolin-containing layer may be equal to about 15% of the total volume of the mixture while the lower layer may amount, for instance, to about 85% of the volume of the mixture of alcohol and spent scouring liquor and will consist of a clear, brown-colored aqueous liquid. Thereby, more than 95% of the amount of lanolin which has been present in the spent scouring liquor in the form of an emulsion will pass into the alcoholic layer. This high effectiveness of the method of the present invention, which is immediately apparent from the clear appearance of the aqueous layer, is best achieved by using aliphatic hexanols. If the aliphatie hexanols are replaced by, for instance, cyclohexanol, benzyl alcohol, heptanols or octanols, such substantially complete separation of lanolin and clarification of the aqueous phase will not be achieved. By using alcohols with between 6 and 8 carbon atoms in the molecule but other than aliphatic hexanols only a partial separation of lanolin into the upper alcoholic layer of lower specific gravity will be achieved while a more considerable portion than 5% of the initially present lanolin will remain in the aqueous phase in the form of an emulsion, as can be seen by the cloudy appearance of the aqueous phase. In view thereof, while the present invention is not limited to utilizing aliphatic hexanols, the latter are the preferred alcohols for use in accordance with the present invention.

The method of the present invention can be carried out irrespective of whether a portion of the original lanolin content of the spent alkaline aqueous scoured liquor has been previously separated, for instance by centrifuging, or whether the spent scouring liquor which is subjected to the treatment according to the present invention still contains its entire original lanolin content. However, if the proportion of lanolin in the spent scouring liquor which is treated according to the. present invention rises then, with increasing concentration of the lanolin, also the residual lanolin concentration in the aqueous phase of the spent scouring liquor treated in accordance with the present invention will increase.

Thus, according to the present invention, the spent scouring liquors obtained by the washing of raw wool with aqueous or synthetic detergent solutions which generally contain sodium carbonate, can be worked up with high effectiveness so as to obtain substantially the entire lanolin content thereof in a relatively pure form, so that the thus recovered lanolin can be easily further processed, including the portion of the lanolin of the scouring liquor which up to now apparently could no be effectively recovered.

It is thus a main advantage of the method of the present invention that the major portion of the lanolin contained in the spent scouring liquor of the type described can be recovered without in any way interfering with the conventional technology and apparatus for the wool scouring process. Contrary to methods for separation or destruction of lanolin which were proposed up to 'now and are in part described above, it is possible to recover not only the portion of the lanolin of the spent scouring liquor which can be separated therefrom by centrifuging but also the emulsified portion thereof which cannot be thus separated, and these two different portions of lanolin may be, as desired, recovered separately or together. Thereby, simultaneously the one component is eliminated from the spent scouring liquor which up to now created the greatest difficulties with respect to purification and disposal of the spent scouring liquor. Thus, pollution of streams or other bodies of waters is substantially avoided by subjecting the spent scouring liquor to the process of the present invention prior to release into such body of water.

It is a significant advantage of the present method that the separation of the lanolin can be carried out without changing the pH of the spent scouring liquor. Thereby, the use of chemical agents for changing the pH and the generally required rather complicated devices for dosing such chemical agents and for controlling the pH of the solution can be dispensed with. In addition, the natural composition of the lanolin is maintained according to the present invention while this composition is usually changed and impaired during changes in the pH of the spent scouring liquor.

Since the amount of alcohol which is to be used in accordance with the present invention may vary within a rather wide range without changing the effectiveness of the process, it is possible to admix the alcohol by means of very simple dosing devices or the like. Thus, the

method of the present invention can be carried out with relatively simple equipment which does not require special control devices and which, except for pumps, requires only the centrifuges which are generally available in conventional lanolin recovery installations, .and conventional apparatus for boiling out of the water or for distilling of the alcohol. A further considerable advantage of the present invention can be found in" the fact that the problems connected with the formation of a sludge layer are avoided and that, in view thereof, it is not necessary to protect the installation against corrosion frequently connected with the working up of the sludge.

The possibility of using a relatively small proportion of alcohol of the type described for separating lanolin from the spent aqueous scouring liquor, and the high yield in which lanolin is thus separated results in a highly economical process. The spent scouring liquor from which lanolin has been removed in accordance with the present invention can be easily further purified by conventional biological methods.

The following examples are given as illustrative only, and without, however, limiting the invention to the specific details of the examples.

Example I A sample of spent scouring liquor obtained from scouring of a lower grade raw wool blend in an alkaline soap and sodium carbonate solution was taken after the spent scouring liquor had been pretreated by centrifuging in the first step centrifuge (type QX 210-79 B De Laval) of the conventional lanolin station, i.e. after the spent scouring liquor had been relieved of the major part of centrifugally separable lanolin and of solid impurities. This spent liquor had a pH value of 9.8 and contained 14.2 grams per liter of emulsified lanolin. The lanolin content was determined in a Soxhlet apparatus as etherical extract from dry matter obtained by steam-stripping of a precise volume of spent liquor acidified by means of phosphoric acid causing slightly acid reaction, and the dry matter was displaced from the steaming vessel quantitatively into an extractional shell by means of sea sand. The ether was steam-stripped from the extract and the residue, after drying to constant weight, weighed as lanolin at 105 C.

A measured amount of the sample was introduced into a separating vessel, 1.5% by vol. of n-hexanol was added at 20 C. and the content of the vessel was shaken manually five to ten times. The mixture of the alcohol and the spent scouring liquor was put into cells of a laboratory cell-centrifuge. After min. centrifuging two distinctly separated phases were obtained-besides a small volume of bottom sludge sediment-the upper one, specifically lighter, consisting of the wool grease or lanolin, of the added alcohol minus the part thereof dissolved in the aqueous phase, and of a small amount of water; the lower, specifically heavier phase was a brown coloured clear liquor consisting mainly of water substantially free of lanolin. The lighter phase was separated from the so treated spent liquor. The grease residue remaining in the thus treated spent liquor was recovered and found to be equal to 354 milligrams per liter, so that the yield from one liter of the so treated liquor was 13.85 grams of lanolin.

The lighter phase was poured into a flask with ground neck provided with a steam pipe discharging at the bottom of the flask and with an outlet for steam leading to a condenser. By means of steam having a normal temperature and pressure n-hexonal was expelled as an azeotropic mixture. Two phases remained in the flask, the lower one consisting of steam condensate pollute-d by suint, detergents and the like from the wool grease, and the upper one consisting of alcohol-free grease recovered.

10 Example II A sample of spent liquor from scouring Australian raw wool with an alkaline aqueous scouring liquor containing a non-ionic detergent (Slovapon) and sodium carbonate, was taken after pretreating of the same on the first step centrifuge (type Nozzle Separator SVK 4 De Laval) in the lanolin station, i.e. after the spent liquor was relieved of a portion of the centrifugally separable lanolin component. This spent liquor had pH value of 8.8 and contained 17.0 grams per liter of lanolin determined as described in Example I. To a measured amount of the sample, in a separating vessel, 1.5% by vol. of n-hexanol was added at 20 C. and the contents thereof were then shaken manually five to ten times. After 60 minutes standing, two separated phases were obtained, the lower one consisting of liquor substantially free of lanolin and containing 510 milligrams per liter of lanolin residue determined as etherical extract in the same manner as in the untreated liquor.

The yield from one liter of thus treated spent liquor was 16.49 grams of lanolin, i.e. 97%.

After 10 min. centrifuging, similarly as in Example I, two separated phases were obtained; the lower aqueous phase contained substantially the same amount of wool grease residue. Alcohol was separated from the upper lighter phase in the same manner as in Example I.

Example III A sample of a non-centrifuged spent alkaline, aqueous scouring liquor obtained by scouring Australian raw wool with an aqueous solution of sodium carbonate and of a non-ionic detergent (Slovapon) was taken. This spent liquor had a pH value of 8.8 and contained 24.2 grams per liter of lanolin determined as in Example I. To measured amounts of the sample, in two separating vessels, 2% and 5% by vol., respectively, of n-hexanol were added at 20 C. After shaking, both samples were centrifuged or allowed to stand. The wool grease residue in the first sample was 2.38 grams per liter, and in the second sample 2.39 grams per liter. Thus the difference was negligible and the yield was 21.82 grams of lanolin from one liter, which corresponds to an efiiciency of 90.25%.

Alcohol was separated from the lighter phase in the same manner as in Example I.

Example IV A sample of spent liquor similar to that described in Example II was mixed at 20 C. with 2% by vol. of cyclohexanol and after manually shaking (five to ten times) it was centrifuged or let stand as in Example II. The aqueous phase, relieved of the major portion of lanoline, contained 950 milligrams per liter of lanolin determined as etherical extract, so that the yield from one liter of the thus treated liquor was 16.05 grams of lanolin, which corresponds to an efiiciency of 94.3%.

The lighter phase after separating from the thus treated spent liquor was poured into a flash from which the alcohol was distilled off in vacuo at C.

A typical scouring liquor which, after having been used for the washing of raw wool, may be freed of lanolin in accordance with the present invention, may have the following composition:

Solvents for lanolin None Sodium stearate or another synthetic detergent, percent 0.125 to 0.2 Sodium carbonate, percent 0.04 to 0.1 pH 8.5 to 10.0

applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A method of recovering lanolin from spent alkaline scouring liquor obtained by scouring of raw wool with an aqueous, alkaline solution of soap or detergents, comprising the steps of mixing a spent alkaline scouring liquor, which is free of solvents for lanolin and has a pH of between 7.5 and about 10, with a hydrocarbyl alcohol having between 6 and 8 carbon atoms per molecule, said alcohol being admixed in a proportion above that which is soluble in said spent alkaline scouring liquor and which is at least equal to about 1% and below 25% of the volume of said alkaline scouring liquor, so as to cause separation of the thus-formed mixture into a heavier, aqueous, substantially lanolin-free phase and a lighter lanolin-containing alcoholic phase; and separating said phases from each other.

2. A method as defined in claim 1, wherein said spent alkaline scouring liquor prior to mixing with said alcohol is subjected to centrifuging so as to remove a major portion of its original lanolin content therefrom.

3. A method as defined in claim 2, wherein said alcohol forms between about 1 and of the volume of said thus-formed mixture.

4. A method as defined in claim 3, wherein said alcohol is an aliphatic hydrocarbyl alcohol.

5. A method as defined in claim 4 wherein said alcohol has 6 carbon atoms per molecule.

6. A method as defined in claim 3 wherein said alcohol is n-hexanol.

7. A method as defined in claim 3, and including the step of subjecting said lanolin-containing alcoholic phase to centrifuging So as to recover lanolin therefrom.

8. A method as defined in claim 7, wherein said centrifuging is carried out at a temperature above C. and up to C.

9. A method as defined in claim 3 and including the step of recovering lanolin from said lanolin-containing alcoholic phase by subjecting said phase to steam stripping so as to expel therefrom an azeotropic alcohol-containing mixture having a boiling point below C.

10. A method as defined in claim 3 wherein said alkaline scouring liquor has a pH of between about 8.0 and 9.5, alcohol is separated from said lanolin-containing alcoholic phase, and at least a portion of the thus-separated alcohol is recycled for admixture to subsequent portions of said spent scouring liquor.

References Cited UNITED STATES PATENTS 271,192 1/1883 Braun et al 260-412.5

632,419 9/1899 Leach 260-4125 XR 1,170,962 2/1916 Chambers 260-412.5 XR

1,476,685 12/1923 Bouillon 260-412.5 XR

2,629,723 2/1953 Lundgren et a1 260-4125 2,692,184 10/1954 Cabot et a1 260-412.5 XR 2,903,424 9/1959 Fong 260-4125 LEON ZITVER, Primary Examiner 5 H. T. MARS, Assistant Examiner