US2034996A - Process of preparing adsorbent clays - Google Patents

Description

March 24, 1936. E M SLOCUM 2,034,996

PROCESS OF PREPARING ADSORBENT CLAYS Original Filed May 21, 1954 HEATING T CHAMBER BLEACHED OILST ZA TREATING HEAT VWEQ HAHGEE BLEACHING C Y Q @g N E o :3 awe/WM D Bow/120 M620 CUM Patent nr. 24, we

PROQESS @F PREP; i? f-r- ADSORBENT WAYS Edward Iii. Sloc, Macon, Ga.

Original application May 21, 1934, Serial. No.

726,823. 2, 1935, Serial No. 152

Divided and this application January 6 Claims. "(comm-2) This invention relates to the bleaching of animal and vegetable oils and fats. It also relates to the activation of bleaching clays and to the recovery of residual oils or fats remaining in spent 5 bleaching clay after the use of such clay in the bleaching of animal and vegetable oils and fats.

This is a division of my copending application Serial No. 726,823, filed May 21, 1934.

The principal object of thisinvention is to provide an improved process of bleaching animal and vegetable oils and fats wherein numerous of the disadvantages attending similar processes here-' tofore employed are avoided.

An important object of the present invention is to provide a continuous process of bleaching animal and vegetable oils and fats.

A further object of the invention is to provide a process of bleaching animal and vegetable oils and fats wherein the apparatus employed is of more simple and inexpensive character than the apparatus commonly employed in similar methods heretofore used.

A further object of the invention is to provide a process of bleaching animal or vegetable oils and fats which is productive of a product of substantially better color and stability than prior processes of bleaching oils and fats.

A further object of the present invention is to provide an improved process of activating bleaching clay.

A further object of the invention is to provide a bleaching clay which is substantially free from water soluble electrolytes.

Another object of the invention is to provide :13 an improved process of reclaiming oil from spent bleaching clay.

Another object of the invention is to provide a. process of reclaiming oils and fats from spent bleaching clay without utilizing the conventional 40' step of blowing the spent clay with air.

Other objects and advantages of the invention will become apparent during the course of the following description.

The method in general use for bleaching animal 45 and vegetable fats and oils is to introduce a large trough is pumped back into the bleaching tank until turbidity disappears and asatisfactory color is obtained. The oil rlmning from the filter press is then pumped into a storage tank, agitation. of the oil and clay being continued until all the oil 5 has been filtered.

After all of the clay has been pumped into the filter press, it is then blown with air and thereafter blown with steamfor the purpose of removing-the residual oil from the spent clay. The oil 0 so removed from the spent clay is very dark and poor in quality so that in most cases it can be used only for making so-called soap powder.

The conventional procedure as referredto'above is often very detrimental to the stability of the 15 oil so' processed. Its resistance to becoming ran old is in many cases cut in half. Another disadvantage is that the oil is heated for a considerable period in the presence of air and in contact with iron, both or which are injurious to the 011. Moreover, the oil forms a hardened film of oxidized oil around the fibers of the canvas filter cloths, reducingv speed of filtration and leading to'the breaking of the cloths. There are several other recognized disadvantages in the conventional bleaching procedure.

One of the most important disadvantaga from a commercial standpoint is the fact that the oil lost in the spent clay runs from 18 to 45% of the dried spent clay. This is'by far the heaviest expense in bleaching oil. The value of the oil lost in the spent clay may be several times that of the clay used in the process. I

As a result of extensive research directedto improving the disadvantageous conventional processes of bleaching animal or vegetable oils and fats, I have devised a method which avoids most of the objectionable features of the present moth- 4 ed in common use.

In a broad way, my process comprises mixing 40 the required amount of bleaching clayfor treating the volume of animal or vegetable fat or oil with a portion of the material to be bleached to provide a, dispersion of the clay therein, to which dispersion may be added treating chemicals of the character hereinafter referred to. This dispersion is then continuously mixed in-required amount with the unbleached oil or fat, the resulta -ing mixture thereafter being heated to'atemperature favorable to the bleaching of the oil or fat and agitated in a bleaching chamber, after which the mixture is. passed to a filter where the bleached material is separated from the spent bleaching clay. It isan important partof process that the material to be bleached is constantly maintained out of contact with the air or oxidizing gases. This is accomplished by employing a closed system which at all times is sub stantially' completely filled with the material ,under treatment, thereby excluding'air without necessity of the creation or maintenance of a vacuum in thesystem; The commercial impor:

tance of my process is also dependent in part on the procedures which I employ for activating the bleaching clay prior to the use thereof in the bleaching process and for recovering oil or fat of good quality from the spent bleaching clay, as

. hereinafterjdescribed in detail.

In the accompanying drawing I have shown in diagrammatic form an assembly of apparatus suitable for use in the practice of my process.

Referring to the drawing, the numeral I 0 designates a storage. tank for the oil or fat to be bleached, which tank is provided with outlet pipes H and I2. The outlet pipe H, which is provided with avalve i3, is adapted to deliver oil or fat into the mixing container H which is preferably provided with a suitable mixing or agitating device IS. The container I4 is provided for preparing the oil or fat'dispersion of bleaching clay, to which dispersion other treating chemicals may be added. The pipe I 6 is adapted to deliver the bleached material from the pipe 2| is passed through the pipe 22 to a heat insulated heat interchanger generally designated by the reference numeral 23, the mixture passing through a coil 24 arranged within the heat interchanger 23 and being discharged therefrom through the pipe 25 which connects with a heating unit 26 having steam inlet and outlet pipes 21 and 28 and heating tubes 29 which may be arranged in the manner of the usual tube boiler construction. The material which passes through the heating unit 26 is delivered by the pipe 30 into a bleaching chamber 3| which is provided with a stirring device preferably in the form of a screw conveyor. The material discharged from the bleaching chamber 3i is passed through the pipe 32 to a coil 33 arranged in juxtaposition to the coil 24 in the heat interchanger 23. The material under treatment is discharged from the coil 33 through the pipe 34 which connects with a union 35 from which the material may be directed through either of the valved pipes 3'8 to a preselected one of a series of filters 31. The filters 31 may be of conventional type such as a leaf filter press, a conventional self-emptying filter press, a centrifugal filter, or the like. While in the accompanying drawing only two filters are designated, it will be apparent that additional filters may be used where required. Each of the filters 31 is provided with an outlet 38 which is adapted to discharge the filtered animal or vegetable oil or fat into the conventional troughs 39 from which the filtered material is carried by pipes 40 which connect at the union 4| to a pipe 42 connected to a pump 43 which is adapted to pump the bleached oil or fat through a pipe 43 into a storage tank 55.

In the preferred practice of my process, specially activated bleaching clay is employed. This is recommended in all cases and is particularly desirable where a leaf filter press is employed in the process and where the clay used would, in the absence of the special activation referred to, be high in water soluble electrolytes and particularly salts of calcium, magnesium and the like, which would form insoluble soaps in a subsequent treatment for removing residual oil from spent bleaching clay.

In order to provide the activated clay which I preferably'employ, the clay in the undried solid v gel state in which it comes from the ground is first subdivided to form granules approximately the size of smallpebbles. The subdivided clay is then introduced into a tank provided with a mixing device and is covered with an acid solution which is thereafter heated to a boiling temperature under ordinary pressure. The boiling is continued until laboratory test shows that the clay has been sufliciently activated. This ordinarily requires from 6 to 10 hours. In treating the clay with an acid solution, practically any acid may be employed, either organic or inorganic, hydrochloric acid, sulfuric acid, and oxalic acid being but three of the many acids which can be employed. I have found that all of the acids are of about equal value and, therefore, it is preferable to use the cheapest, i. e. sulfuric acid. The acid solution which is employed is preferably of about 60% strength although it will be obvious that the strength of acid is subject to great, variation. The amount of the acid solution employed is also subject to great variation but it is recommended that sufficient acid solution be used to completely cover the subdivided particles of clay in the-treating container.

After the boiling treatment has been carried out for the required period oftime, the excess of acid solution is drawn off and water is sprayed on to the mass and permitted to trickle through. This spraying treatment'thoroughly washes out all water soluble electrolytes present in the clay.

It is of course recognized that activation of bleaching clay by acid treatment is an old procedure. However, in the processes heretofore employed it has been customary to treat dried crude bleaching clay with Water to reduce the clay to a pulp or mudded condition, after which the clay is treated with an acid. It has been found that it has been substantially impossible satisfactorily to remove water soluble electrolytes from the clay thus treated and in no instance has it been possible to thoroughly wash such clays by spraying. As pointed out above, I have discovered that if the clay is treated in the undried solid gel state in which it occurs in the ground instead of in the pulp or mud form in which it is usually treated, the water soluble electrolytes may be conveniently and easily removed by merely spraying water over the particles of clay in a container. Tests have demonstrated that bleaching clay activated in the manner described above is substantially free from water soluble electrolytes, the amount of such electrolytes being reduced below about one-hundredth of one per cent. These clay particles after washing are suitable not only for drying and grinding to produce a commercial bleaching clay but, without drying or grinding, are suitable for other purposes, such as in water purification systems.

amount of oil to be bleached is weighed into the mixing tank It. The amount of clay employed is determined in conventional manner by laboratory test and, in general, ranges between approximately 0.5% and 1.25% on the weight of the oil or fat to be bleached. From the storage tank ill, sufficient of the oil or fat therein is delivered through the pipe I I under the control of the valve l3 into the mixing tank M. This oil or fat should be at as low a temperature as the solidifying point of the oil or fat will allow and still have the material thoroughly liquid. This temperature is, roughly, between60 and F. The amount of material introduced into the mixing tank id from the storage tank i0 is subject to considerable variation but I have found it advantageous to mix with the bleaching clay about nine times its weight of oil or fat from the tank id. The agitator i5 is then started so as to mix the clay into a smooth dispersion with the oil or fat. As

'will be apparent, instead of using but one mixing tank Id, several such tanks may be employed.

In preferred practice, I also introduce into the mixing tank id certain treating chemicals to be incorporated with the dispersion therein. However, these chemicals may be added separately or together later in the process by introducing them directly into the system or by the use of separate mixing tanks. However, in order to avoid unnecessary handling of materials, it is preferable to mix the treating chemicals with the dispersion in the tank id.

One of the treating chemicals which I recommend be incorporated with the material to be bleached is an inhibitor of enzyme and bacterial action. I have discovered that water soluble halogen compounds are particularly suitable for this purpose, such as ammonium and alkali metal bromides, fluorides, iodides and chlorides and their complex ions. In preferred practice I employ sodium fluoride. Of the soluble halides, sodium chloride is the least effective inhibitor but even it can be used with some measure of success. The amounts of the soluble halides employed will vary greatly as will be apparent to those skilled in the art. The amount required is determined by subjecting the oil or fat to be treated to the conventional stability test. Generally, the amount used will range from onefiitieth of one per cent. to one-tenth of one per cent. on the weight of the material to be bleached.

I have also found it advantageous to incorporate an anti-oxidant with the dispersion in the mixing tank id, preferably one which does not tend to discolor animal and vegetable fats and oils. Various suitable anti-omdants are known, such as the various derivatives of pyrogailol and other strongly oxygen-absorbing organic chemicals, such as diphenols. The anti-oxidant is generally employed only in traces, say one-fiftieth oi one per cent. on the weight of the material being bleached If desired, carbon black may also be incorporated in the dispersion prepared in the mixing tank id. As is well known, carbon black is irequently employed in the bleaching of animal or vegetable fats and oils for the 'purpm of delaying rancidity. However, I have found that it is not necessary to employ carbon black in the present process and since its use may prove troublesome, I prefer not to employ this material. However, it can be employed if desired and, if used, it is introduced in the approximate amount of four pounds of carbon black to one hundred thousand pounds of the material to be bleached.

Asset forth above, the treating chemicals need not beadded in the mixing tank id but may be subsequently introduced into the system; These are preferably introduced in solution or suspension in a portion of the oil or fat being treated.

From the tank it? the dispersion therein is mixed by any suitable means with a definite volume of the oil or fat to be processed. In preferred practice, I accomplish this by the use of pumps l l and 26 which convey the dispersion from the tank id and the oil or fat to be processed from the tank It to the union lt'where the mixing takes place. The pumps are set so as to mix the correct volumes of the oil or fat from the storage tank ill, which ordinarily has been subjected to the usual preliminary refining treatment, with the dispersion from the tank it. For example, if preliminary tests indicated that 1% of the bleaching clay on the weight of the oil or fat should be employed. and a 10% clay dispersion had been prepared in the tank M3, approximately nine parts of the oil or fat to be bleached would be mixed with one part oi the 10% dispersion.

After the mixing oi the unbleached material and the clay dispersion, the mixture is passed through a heating device and the hot mixture is then sent through a closed container, equipped with a stirring device, of such dimensions that the oil or fat leaving it has been bleached and purified to the desired degree. apparatus should be designed so that, where an activated quick-bleach clay is employed, a perind of about eight to fifteen minutes will be required for the passage of the material from its point of mixture, say at the union E9, to its point of discharge from the bleaching chamber. bleaching temperature to be employed will, of course, vary considerably according to the material under treatment, the purpose for which the bleached material is to be employed, and other factors well known in the art. As a general rule, the bleaching temperature employed varies rough- Ordinarily, the

ly from to 300 F. Since the present process safely allows the use of high bleaching temperatures without injury to the oil, I prefer to heat the oil to a high bleaching temperature, since the higher the temperature, the better the bleach. f

In the preferred practice of my process, the mixture of material to be bleached and the clay dispersion is passed from its point of mixture at the union it, through the pipe 22 into the coil 26 arranged in the insulated heat interchanger 23 where there is imparted to the unbleached material a portion of the heat from bleached material passing in a countercurrent direction through the juxtaposed coil 33. The material is passed from the coil 26 through the heating unit '26 where it is heated up to an elevated temperature, say up to 300 F. Thereafter the material is passed through the bleaching chamber 39 where it is thoroughly stirred by the screw conveyor therein. From the chamber 38 the bleached material and spent clay dispersion is passed through the coil 33 in the heat interchanger 23 and out of the heat interchanger through the pipe 355. In the preferred practice of the process, the material passing through the pipe 36 has been cooled to a temperature in the neighborhood of F.

The material at this point is then conducted to a suitable filter to remove the bleached oil or fat from the associated spent bleaching clay. In preferred practice, I employ a series of filters of sullicient number so that there will be at least one filter available while the spent clay in the other filters is being removed therefrom or being treated rected-through-the pipes 86. As shown, each. of

the pipes is provided with a'valvein order that'the materialfrom the pipe 34 may be directed'to th proper filter.

I'may useany suitable conventional filter such as a leaffilterpress, a so-called self-emptying filter presaa centrifugal filter or the like. The. bleached oil or fat passing through the filter is .then subjected to such additional refining treatment as may be desired, such as a conventional deodoriaing treatment, after whichit is 'intrc'- duced into a storage tank.

When the bleached oil or fat is to be left in storage tanks for any substantial period, it is preferable to store the material in contact with a non-oxidizing gas such as methane, which may be derived from natural gas, nitrogen,- carbon dioxide or the like. When a fat or oil is to have a gas beaten into it to provide an emulsion of the fat or oil with such gas, as isthe practicewith much of the compound shortening now manufactured a non-oxidizing gas such as methane, nitrogemcarbon dioxide or the like should be used in place of the air now commonly used. An oil or fat thus treated will be found to be more stable than a similar oil or fat which has had air beateninto it. 7

As stated above, in the ordinary process of bleaching animal or vegetable fats and oils there is ordinarily lost about 18 to of the oil on the weight of the clay due to its retention by the spent bleaching clay and where a portion of this oil has been recovered, the quality of the recovered oil was so poor that it could not be marketed as high grade oil. In the present process, I have provided a method of reducing the oil loss to about 7% in one embodiment and to about 15% in another embodiment of the process.

. Where theoil is filtered with conventional leaf filter presses, the first unit employed is closed after it has been used for sufiicient time to render its further use impractical and the material under treatment is then directed to another similar press which is ready for use. The spent clay in the first unit is then washed with a cold or luke-warm soap solution. Any convenient method of applying the soap to the spent clay may be employed. In preferred practice, there is sent through the first filter press unit containing spent clay and bleached oil. in its press leaves an oil dispersion of a water soluble soap. The soap is preferably suspended in a portion of the refined material being treated. For example, if cottonseed oil is being bleached, the soap is suspended in refined cottonseed oil and this dispersion is forced through the press under treatment. This is continued until sufficient soap has been deposited in. the spent clay to permit it to be washed thoroughly. The amount of soap to be deposited will vary according to the particular conditions in a particular plant but, in general, the soap would approximate between one-tenth of one per cent. and one per cent. on the weight of the spent clay to be processed.

When a sufiicient amount of soap has been deposited the supply of the oil dispersion of soap is cut off and cold or lukewarm water is then sent through the spent clay in the press. If too hot water he sent through the spent clay it will not hydrate the clay sufficiently to reduce the surface attraction of the clay for the oil.

The water passing through the spent clay washes the liberated oil through, thefiltercloths and the resulting mixture of oil and water is then introduced into a container where it is permitted to stand so that the'oil may beseparated from channels. Thereafter, water is again introduced into the press and this may again befollowed by a second treatment with an elastic gas such as steam and a third treatment with water.

As a result of this treatment the oil lost in the spent clay may be reduced to approximately 15%- of the dry spent clay.-

There are several other advantages attending this method of treating spent clay in leaf filter.-

presses. The bleached oilis" removed from the filter press substantially completely without blowing the press with air as is now the usual method. This use of air injures the oil removed by it, as well as the oil still remaining with the spent clay in the press.

After the treatment described, the press cloths are washed with soapy water following each use of the filter press. The amount of oil left on the fibers of the press cloths is definitely lessened. The press cloths are thus cleaner, they filter more freely, and last longer.

Where in the above referred to treatment cold or lukewarm water is used, the alkaline soap solution reduces the free fatty acids in the recov ered oil. The soap also dissolves some of the color from the recovered oil. What color is developed is very readily bleached out so that the recovered oil without loss of quality in the finished product can be added to the next batch of oil to be bleached. This is not true of the oil recovered by the air-steam blow method.

The above described treatment of the spent clay with soap is successful only with bleaching clay whose content of soluble lime and magnesia, and other injurious metallic salts, is low enough not to form insoluble metallic soaps on the surface of the clay particles and so prevent the passage of liquid through the spent clay. Therefore, as pointed out above, when filtering is done with a leaf filter press and the raw bleaching clay contains a substantial amount of these injurious compounds, the clay should be activated in the manner described above in order that the clay may be substantially freed from water soluble electrolytes.

Instead of using a leaf filter press for separating the bleached oil or fat from the spent bleaching clay, I may use any convenient known type of self-emptying filter press or any convenient known type of centrifugal filter. If a self-emptying press is employed, metallic filter cloths can be used. If a centrifugal filter is employed I prefer to use a type which can be rapidly freed of the solid phase and also a type in which an inert gas atmosphere can be maintained in contact with the filtering oil or fat.

Where a self-emptying press or a centrifugal filter is used, it is preferable to treat the oily spent clay apart from the filter rather than in the filter as where a leaf filter press is employed.

iii

aoeaoee Accordingly before treating the spent clay to recovertherefrom the oil or fat retained thereby, the spent clay should firstbe removed from either the self-emptying filter or the centrifugal filter.

The spent clay which has been removed from the filter is preferably run into a tank which When the water has thus been run in, the oil or fat which has been liberated by the treating chemical rises to the top while the clay settles to the bottom as a thin mud. The oil is then lhawn ofi from the surface of the water and the clay mud run into the sewer. Since the spent clay remains in a light condition which will not form heavy gummy deposits it can be safety emptied into a sewer. By the above treatment the oil or fat present in the clay is reduced to about 7% on the weight of the dry spent clay.

I have found that there are three difierent classes oi reagents which may be employed to reduce the surface adhesion of the spent clay toward the oil or fat in the treatment above described. For example, soluble fluorides may be satisfactorily employed, and I prefer to use an aqueous solution of sodium fluoride for miring with the spent clay to be processed. The amount of sodium fluoride to be employed in preparing the aqueous solution will, of course, vary substantially but the exact amount can readily be determined by previous laboratory trial. Ordlnarily sodium fluoride in the amount or from V of 1% to A; of 1% on the weight of the clay is sumcient.

A second class of reagents capable oi reducing the surface attraction of the spent bleaching clay for certain oils and fats are coagulating polyvalent kations, specifically, soluble salts of iron, manganese, chromium and aluminum. When one of these metallic salts is employed it may be present, for example, to the extent of from 1 to.1o% on the weight of the spent clay being treated.

A third class of reagents capable of reducing the surface attraction of the spent clay for cer== tain oils and fats are coagulating polyvalent anions, specifically, soluble salts of amphoteric metal acids, such as sodium aluminate, sodium stannate, sodium tungstate and the like. When one of these salts is employed it may be present, for example, to the extent of say of 1% to 5% on the weight of the spent clay being treated.

After the oil or fat which has been separated from the spent clay has been recovered, it is ordinarily advisable to add the recovered material to another batch of oil or fat to be bleached, although in some-instances this will not be found desirable since the material without further treatment may be put to other uses than the main body of oil or fat which has been bleached.

As will be apparent from the foregoing, my process possesses numerous advantages over the processes heretofore employed for the bleaching of animal and vegetable oils and fats. In the first place, the process is a continuous one which is obviously a very important advantage over the prior art processes customarily employed. Moreover, the process maintains the oil or fat out of contact with any great quantity of air or oxidizing gas throughout the process and yet avoids the necessity of creating or mainta a vacuum in the system. Where a quick bleaching clay is employed, as in the preferred practice or the process, a small apparatus can be employed.

Such a small apparatus may, without running into prohibitive expense, be made of metals or alloys more suitable than the iron or brass now in common use in bleaching kettles and filter processes. Another important advantage or the process is that there is no necessity to blow the 4 niter medium with air to decrease the amount of oil entrained thereby. The oil or fat recovered in the process is oi lower acid content and in better condition than the oil recovered by the present air and steam treatment. The oil lost in the spent clay is substantially smaller in.

amount than that lost after air-steam blowing. There is no solvent lost nor solvent to be removed from the recovered oil or fat as in the organic solvent methods of recovery from spent clay. Where leaf presses are used for filtering, the

press cloths are left cleanen-filter more rapidly and last longer thanin the case of prior processes using leaf presses. used for filtering in the process, if desired. the oily spent clay from self-emptying presses can be easily treated to give low oil retention. The spent clay after treatment to remove entrained oil or fat is a light pulp which can be run into a sewer without difficulties resulting from gummy changers between bleached and unbleached oils.

The optimum bleaching temperature can be maintained in the bleaching chamber while maintaining the oil or fat out or contact with the air without the necessity of creating or maintaining a vacuum in the bleaching chamber. If self-emptying presses or inert gas types of centrifugals are employed, the oil can be filtered at temperatures most convenienu for rapid filtration and the oil can yet be kept out of contact with the air. The use of an inhibitor of enzyme and bacterial action not only inhibits the lipasesplitting of vegetable and animal fats and oils but these inhibitors also serve as disinfecting agents against moulds, yeast and bacteria. Since the water soluble halides employed as inhibitors Self-emptying pressescan be are insoluble in oils and fats, they do not afiect the oils or fats themselves. When the dispersed crystals come in contact with wet colloidal seed pulp dispersed in oil, the lipase in it is rendered inefiective and the pulp material itself is no longer food for moulds, yeast and bacteria. Oils and fats stored in contact with an inert gas or in which an inert gas has been dispersed possess increased protection against oxidation. Finally, it has been demonstrated that the animal and vegetable oils and fats processed in accordance with the present invention are stable against rancidlty for a substantially longer period than the oils and fats treated in accordance with the usual prior practice.

The term bleaching clay" as employed herein is not intended to be restrictive to any one class of clays, but is to be understood as including all arglllaceous material, such as bentonlte, semiis adapted to remove color from vegetable andanimal oils andfats.

In the practice of the above described process,

the water which is employed in washing the ac- .tration of injurious ions.

tivated bleaching clay after it has been subjected I to an activating agent should be low in concen- For example, a water approaching zero hardness should be employed.

Obviously, materials other than acids may be ,used in activating bleaching clays and it is an important feature of my invention that where the bleaching clay is activated either with an acid or other activating agents, the water soluble materials remaining in the clay can be readily washed out if the clay is treated in the form of clay granules in solid gel state. While I have referred above to the washing of such clay granules by spraying water thereon and permitting the water to trickle through'the mass, it will be apparent that washing may be accomplished by any other suitable means which involves the relative movement of the washing water with respect to the clay. granules.

As pointed out above, I prefer to employ in the practice of the present process an inhibitor of enzyme and bacterial action which comprises a soluble halide. .While, as stated, this material is preferably added to the oil dispersion of clay in the mixing tank [4, and passes through the system in the presence of the clay, to be substantially filtered out when the bleached material is passed through the filter, I have discovered that it is also advantageous in treating edible fats and oils which are not bleached or which may not be bleached by a process of the character above described to add to such edible fat or oils 2. minor proportion of a water soluble but oil insoluble halide and, thereafter, to substantially remove the crystals of the halide as by filtering. While the filtering will remove the major proportion of the crystals of the halide, there will still be left traces of the halide which will be sufiicient to exhibit enzyme and bacterial action without injuring the digestibility of the treated oil or fat. As is well known, in expressing edible oils from nuts or seeds, the nuts or seeds are cut into small pieces and subjected to great pressure whereby the oil is pressed out. This oil always contains a considerable roportion of pectinous material from the cells of the nuts and seeds. While a substantial proportion of this pectinous material can be removed by filtration and other treatment, a portion of this organic material which is present in colloidal condition cannot be removed. It is very finely dispersed in the body of the oil so that it will pass through an ordinary filter. It is this filterable dispersion of colloidal organic material which is considered to be responsible for the spoiling of the oil through rancidity. By adding a water-soluble, oil-insoluble inhibitor of enzyme and bacterial action, as described above, the dispersion of pectinous material present in the body of the oil will take up some of the inhibitor so as to prevent enzyme and bacterial action. As pointed out above, the inhibitor preferably consists of a water-soluble, oil-insoluble halide, preferably a water-soluble, oil-insoluble fiuorine compound, and this material is preferably added in the form of crystals of small particle size. When the treated oil is filtered, the crystals of the fluorine compound will be removed from the oil itself but a small portion of the inhibitor will be dispersed in the filterable pectinous material which is I. through the oil. Of course, the particles of-"the fluorine compound having been filtered out of the 1 oil itself and the amount of fluorine compound dispersed in the pectinous material being small,

the final-product 'will not be injured with rc-' spect to taste or digestibility, although stabilized against enzyme and bacterial action.

Where reference is made herein to activating;

bleaching clay it is to be understood that the term activating is used in its common acsubjecting .of the bleaching clay to the action of cepted technical sense, i. e. as applying to the 4 an acid solution to remove some but not all of f the basic constituents of the silicate. complex, whereby the resulting product remains as a hydrated silicate of alumina and not a silicic acid.

The term bleaching clay as employed herein is used in its commonly accepted technical sense, i. e. as applyingto an argillaceous hydrated silicate of alumina possessing marked adsorptive powers and having the characteristic of readily sliming, by which is meant that when dried and placed in water or a conventional activa g acid solution it will readily disintegrate into a slime or mud or pulp. The term does not include, and

is not intended to cover herein, shale-like substances containing notable proportions of calcium and magnesium carbonate, such as certain fullers earths which are essentially rock-like. Moreover, the term does not include, and is not intended to cover herein, kaolins which do not possess marked adsorptive powers either before or after treatment with an acid activating agent, or stable silicate aggregates, such as the glauconites or green sands, which are essentially rock sands.

While I have described in detail the preferred practice of my process and several modifications thereof, it is to be understood that the details of procedure, the arrangement of steps, the proportions of ingredients and the like,-may be variously modified without departing from the spirit of the invention or the scope of the subjoined claims.

I claim:

1. In a process of activating readilysliming bleaching clay wherein the clay is subjected to the action of an acid solution and the acid-activated clay is thereafter washed, the improvement which comprises treating with the acid solution bleaching clay which is in its original gel-like form and which contains sufiicient of its original water content to prevent substantial disintegration of the clay into a pulp or mud during the treatment with the acid solution.

2. In a process of activating readily sliming bleaching clay wherein the clay is subjected to the action of an acid solution to activate the same, the improvement which comprises treating with the acid solution bleaching clay which is in its original gel-like form and which has retained up to the point of such treatment with acid solution suflicient of its original water content to prevent substantial disintegration of the clay into a pulp or mud during such treatment with acid solution, and washing the substantially nondisintegrated clay substantially completely free from water-soluble electrolytes.

3. In a process of activating readily sliming bleaching-clay wherein the clay is treated with an acid solution to activate the same and the acid-activated clay is thereafter washed, the imment with acid solution which comprises subjecting to the acid treatment bleaching clay which isin solid gel-like state and which has substantially the same water content as said clay had when in the ground.

4. In a process of activating readily sliming bleaching clay wherein the clayin the form of subdivided lumps is treated with an acid solution to activate said clay, the improvement for preventing substantial formation of a pulp or mud and for retaining the clay in said lump form upon said acid treatment which comprises subjecting to the acid treatment subdivided lumps of bleaching clay which is in solid gel-like state and which has substantially the same water content as said clay had when in the ground, and washing the resulting lumps of activated clay substantially completely free from water-soluble electrolytes.

5. A product of the character described comprising lumps of acid-activated clay in solid gellike state, the form of said lumps being substantially the same as the form imparted to the original clay prior to acid-activation thereof, said original clay being of readily sliming type, the

r lump form of said acid-activated clay permitting rapid washing thereof substantially completely to remove water-soluble electrolytes therefrom.

6. A product of the character described comprising an adsorbent, acid-activated clay in the form of lumps corresponding substantially to the form of the original clay when subjected to acidactivation, said original clay being of readily sliming type, the clay in said lumps being in undried solid gel-like state, said product being substantially free from water-soluble electrolytes.

EDWARD M. SLOCUM.

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