US3055835A

US3055835A - Drying process for detergents

Info

Publication number: US3055835A
Application number: US774723A
Authority: US
Inventors: Monick John Alexander
Original assignee: Colgate Palmolive Co
Current assignee: Colgate Palmolive Co
Priority date: 1958-11-18
Filing date: 1958-11-18
Publication date: 1962-09-25
Anticipated expiration: 1979-09-25

Description

Sept. 25, 1962 J. A. MONICK DRYING PROCESS FOR DETERGENTS Filed Nov. 18, 1958 T"lI E .1.

MI, il'h IN VEN TOR. JOHN A Mo/v/cx ATTORNEY 3,055,335 DRYING PROCESS FDR DETERGENTS John Alexander Monick, Teaneek, N..l., assignor to Colgate-Palmolive Company, New York, N.Y., a corporation of Delaware Filed Nov. 18, 1958, Ser. No. 774,723 4 Claims. (Cl. 252Ir38) The present invention relates to a new drying process particularly suitable for drying detergents to obtain them in free flowing, non-dusting, stable, globular forms which will resist breakage during handling. More particularly, the invention comprises a drying process wherein an aqueous solution or slurry of detergent is sprayed under special conditions including relatively high solids content, heated mix, high spraying pressure and spray orifices of a certain small size, into heated drying gas.

The method of drying solutions and slurries by forming a spray thereof and passing it through a hot drying gas medium, the so-called spray drying process, has become of increasing utility and popularity in recent years. Among other compounds, synthetic detergents and soaps have been spray dried, usually after first being compounded with fillers and builder materials. In some of the known processes for manufacturing commercial detergent beads, a crutcher mix of active ingredient and inorganic builder has been sprayed through relatively large nozzles, e.g., 7 to A inch diameter, at comparatively low pressure, e.g., 50 to 100 lbs. per sq. in. abs., into countercurrent or concurrent drying towers. In other methods, spinning disk atomizers and relatively short or conical drying chambers have been used. To make a particular low density alkyl aryl sulfonate product there has been employed a combination of low solids content crutcher mix and low pressure spraying into elongated vertical drying towers.

All of the previous methods of making built or filled alkyl aryl sulfonate product by spray drying techniques have been found to entail certain disadvantages which have limited their scope of applicability. In many instances the beads produced were of such small particle size that they behaved like dust, causing irritation to workers and annoyance to the users. These fine powders have also been found to be excessively tacky, agglomerate, often block filling equipment, and cake in the shipping container and end use package. Products of other processes mentioned above were of comparatively large particle size and of low wall thickness so that in ordinary handling or converting, or even in the air-lifting, which is a part of many spray drying processes, the particles were broken, often pulverized, making a dusty powder instead of attractively sized beads. When spraying pressure was low and low bulk density beads were made from crutcher mix containing excess water, e.g., 65 to 75%, tower throughput was substantially reduced and it was not possible to manufacture a variety of products of a wide range of pie-selected densities.

I have overcome the above difiiculties with respect to a certain type of detergent composition by my discovery that the presently claimed method allows the production of alkyl aryl sulfonate detergents in free flowing non-dusting stable globular particle forms at high production rates. The invented method permits the manufacture of these products at any desired bulk density from .16 to .50 gram per cubic centimeter and may be used in either countercurrent or concurrent spray towers, being substantially 3,055,835 Patented Sept. 25, 1962 unafiected by the temperatures of the tower and drying gas in the spray region. In accordance with the present invention there is provided a process for drying detergents which consist essentially of a mixture of 10 to water soluble alkyl aryl sulfonate detergent and to 20% water soluble inorganic salt selected from the group consisting of sodium sulfate, sodium chloride, sodium silicate and sodium tripolyphosphate, the so-called pentasodium salt. From this process there are obtained nondusting free flowing, stable particles which resist breakage during handling and are substantially all beads of substantially globular shape with diameters within the range of .075 to .85 millimeter, containing very small quantities of fine-s. The process comprises making an aqueous crutcher mix containing 40 to 65% of alkyl aryl sulfonate detergent and said inorganic salt or mixtures thereof and 60 to 35% water, and containing substantially no entrained gas, heating the mix to a temperature of to 210 F., spraying the mix at a pressure of 500 to 1500 pounds per square inch through an orifice of diameter between 2.0 and 3.2 millimeters in a conical spray pattern into heated drying gas and drying the sprayed particles to a form retaining, substantially globular particulate product of low moisture content.

The advantages of the invention, as well as various objects thereof, will be apparent from the following description of the drying process and the processing equipment employed, taken in conjunction with the accompanying drawing in which:

FIG. 1 is a schematic elevation of the spray drying apparatus employed together with auxiliary equipment; and

FIG. 2 is a sectional elevation of a spray drying nozzle having a small orifice for creating the proper spray dispersion pattern.

Numeral 11 designates a spray drying chamber, in this case a tower, in which hot drying gas evaporates moisture from atomized detergent slurry, producing small particles of detergent in head form. The driving process begins with the making of a slurry of desired components of the detergent in the mixer known in the art as a crutcher 13, here shown as two crutchers to permit continuous production. When the slurry is being made in one of the crutchers that previously mixed in the other is being pumped to the drier. As represented in the drawing the detergent base, which is an aqueous solution of alkyl aryl sulfonate containing sodium sulfate resulting from neutralization of excess sulfonating agent, is fed to the crutcher through suitable conducting and feeding means 15 from base tank 17 which is equipped with a stirrer to minimize settling. Similarly, other desired constituents, which may be sodium sulfate and pentasodium tripolyphosphate, are added in powder form from bins 19 and 21.

After agitation for the requisite time, which is usually about twenty minutes or a half hour, the crutcher mix is allowed to flow into :a drop tank 23. From the drop tank it passes through a motor driven power strainer 25 and a booster pump 27 to a vacuum :deaerator 29 where it is spread out intoa thin film which is subjected to low pressure to remove entrained and dissolved gases, such as air. Exemplary of such a machine is that known as the Vers-ator. The deaera-ted slurry leaving the Versator is next ground in a slurry grinder such as the Fitz or Reitz wet mills, represented by 31, to reduce any particles that might block spray nozzles or cause formation of irregular spray particles. constant source of slurry for high pressure positive displacement Triplex pump 35 which raises the pressure to 500 to 1500 lbs. per sq. in. Before atomization into the spray tower at the spray nozzles 39 the mix is further heated above its crutching temperature in a heat exchanger 37, manifold or steam jacketed line to 120 to 210 C. After being sprayed from nozzles 39 through orifices 41 into the desirable hollow conical spray dispersion pattern the drying droplets fall through the tower through upwardly flowing drying gas, forming globular hollow beads which are resistant to breakage during handling, converting and shipment. The dried beads are non-tacky because of their composition and shape, and also because of the degree to which they have been dried and the nature of the process. They may be cooled by special apparatus whch can be installed in the tower bottom but in the process illustrated cooling is effected in the drier cone 43 and on the vibratory conveyor 45 which delivers the product to airlift 47. Usually the beads should be cooled to 100 to 140 F. and should be air-lifted by air at that temperature to minimize breakage of the beads. Warm air for the lift may be obtained by bleeding some excess drying gas into the lift at a convenient point.

At the top of the lift the mixture of lift air and detergent particles is separated in a product collector cyclone 49 and the detergent is screened 51 and stored in a bin 53 at a packing station. The air and entrained fines are passed through a dust collector 55, often of the bag type. Detergent dust is blended back with future crutcher mixes and the air is exhausted to the atmosphere through blower 57.

Tracing the gas part of the system, numeral 59 is a furnace heating drying gas which enters the tower count ercurrently through plenum 61 and passes upwardly, giving up its heat to the falling detergent droplets and beads. From the top of the tower the gas passes through a cyclone or Ducon collector 63 which removes any fine powder that might have become entrapped in the outrushing gas. The solids are recycled to the crutcher and the air is exhausted by blower 65.

In FIG. 2 is illustrated a spray nozzle or nozzle-block assembly 39 of a type which has been found to be uniquely suited for use in the invented processes to obtain good beads of desired bulk densities. As illustrated the block may be visualized as a horizontal cylindrical member bored part way through from the ends and threaded. Plug 69 and gasket 71 have blanked oif one end and in the other is inserted bushing 73. Connecting bushing interior and block hollow 75 is passageway '77 which enters hollow 75 tangentially. Within the hollow is a pin 79 which, in conjunction with the tangentially entering passage, causes slurry entering the spray nozzle to pursue a whirling, helical path before being forced out orifice 41 in thimble insert 81 held in place on block 39 by retainer 83; Due in part to the whirling action in the nozzle block the slurry forced through the assembly under high pressure atomizes into a hollow cone spray pattern from which stable globular beads results which are strong enough to resist breakage during handling and transportation.

Although the process may be applicable to drying other solids, and other detergent compositions, the criticality of spraying pressure, orifice size, and crutcher solids content, and the poor product resulting when any of these conditions is appreciably outside the disclosed ranges, in dicate a dependency of result on the composition too. It is known that many organic detergents would not yield strong non-tacky free flowing bead product, even when treated according to the invented process. Similarly, several conventional builders and fillers would also be unsatisfactory. For these reasons the invention relates to the alkyl aryl sulfonate detergents with the four dis closed inorganic salts, or mixtures thereof, as the other major components.

Surge tank 33 provides a 1 Among the alkyl aryl sulfonate detergents that which is made by alkylating benzene with a polymer of lower alkene, e.g., propylene tetramer, and then sulfonating and neutralizing to the sodium salt, e.g., sodium dodecyl benzene sulfonate, is preferred. Alternatively, other such detergents wherein the alkyl group is a polymer of 12 to 18, preferably 12 to 15 carbon atoms may also be used. These may be derived from such lower hydrocarbons as propylene, butylene or isobutylene.

The amounts of alkl aryl sulfonate employed in the formula of the detergent product may be between 10 and In a highly preferred range, 30 to 50% of such active ingredient is used. It is found that the detergents of higher active ingredient content can be dried satisfactorily by taking care to keep the spraying and crutcher mix temperatures at the lower portion of the range and by using lower drying gas temperatures to avoid decomposition and charting. It has been established that strong non-tacky products, having low content of inorganic salt, can be made when about 3 to 10% sodium silicate is added. This particular inorganic salt compound is also especially useful as a carrier and builder for other tackier detergent compositions which might be employed.

Among the inorganic salts used in detergent compositions, sodium sulfate, pentasodium tripolyphosphate and sodium silicate, all hydrated salts, have been employed with alkyl aryl sulfonate to make a number of products of desired density within the 0.16 to 0.50 gram per cubic centimeter range. These salts behave similarly and are the best components of the products of lower density within that range. The density of such products can be raised within the limits given by the addition of sodium chloride, preferably 3 to 15%, which, in these compositions and under the particular processing taught, raises bulk density to the desired figure. The inorganic salt content of the sprayed detergent beads may range from to 20%, with 70 to 50% being most preferred.

It will be seen that the amounts of alkyl aryl sulfonate and water soluble inorganic salt total in the ranges given. Of course, it is evident that various additives and supplemental ingredients may be present, providing that the product consists essentially of these two major classes of materials. Among the additives may be mentioned bactericides, sequestrants, coloring and perfuming agents, soil suspending compounds, foam enhancers, other detergents, etc. Usually the total amount present will not exceed 10%.

To obtain a detergent which is within the 0.16 to .50 gram per cubic centimeter density range, preferably .20 to .50 gram per cubic centimeter, and is neither dusty nor tacky, the product should be substantially all in globular bead form and of a particle size such that it will pass a 20 mesh screen with less than 1% through a 325 mesh screen. Substantially all, or over 90% of the material should be above 100 mesh in size. As to the nature of the particles, over 75%, preferably over 85% should be present in unbroken globular bead form. This form minimizes tackiness and aggregation, facilitates flow, dissolves readily and is attractive to the consumer.

In spraying these detergents it has been noted that it is necessary to keep the crutcher mix at 40 to 65% solids content, including organic detergent and inorganic salt. The balance of 60 to 35% is water. If the solids content is allowed to drop to 30 to 35% the product made will be of too low a density and often will be so fragile that beads will be easily broken in handling. This is also often the case when spray pressure is reduced appreciably below 500 pounds per square inch, the allowable spray pressure range being 500 to 1500, preferably 500 to 1000 pounds per square inch. Similarly, if the spray orifice is of a diameter outside the 2.0 to 3.2 millimeters range the product will often be unacceptable. If the orifice is over 3.2 millimeters diameter beads made will fracture easily, while at lesser diameters than 2.0 millimeters the tower throughput rate will be uneconomical, extremely high pressures will be required and tower losses will be increased.

The crutcher mix is heated before spraying to a temperature of 120 to 210 F. preferably 140 to 200 F. The lower temperatures, 120 to 140 F., are used only when organic detergent content is high, to prevent decomposition. The mix may be crutched at the spraying temperature or heated prior to spraying, as is convenient. Usually a heat exchanger immediately preceding the spray nozzles will raise the spraying temperature to 140 to 160 F. Raising the temperature of the material to be sprayed has little effect on the gravity of the product made unless degasification is facilitated, in which case density is increased. However, when a product of 30 to 50% organic detergent is being made it is best to have the mix at 140 F. or higher since lower temperatures produce weaker particles than desired.

To make detergent of most consistent density throughout the spraying period the entrained and dissolved gases are removed by vacuum treatment. In a thin film deaerator, such as the Versator a pressure of less than inches mercury absolute, most preferably less than 10 inches, is used to substantially completely degasify the mix. A comminutor or wet grinder reduces the size of undissolved particles to less than the orifice width to prevent blocking and shutdowns which might destroy tower equilibrium. 1

The sprayed detergent is emitted from the nozzles of the design described (usually a plurality is used) in hollow cone pattern, into a drying gas, usually air heated to a temperature of 200 F. to 650 F. Other types of nozzles may be used if the spray size and pattern are the same as that obtained from the illustrated structure. It is a feature of this invention that the temperature of the drying medium into which the mix is sprayed has little effect on particle size or bead shape. Thus, the drying method may be either countercurrent or concurrent, providing that it is so regulated as to result in substantial drying to a moisture content less than about 5%, preferably of 0.5 to 3%.

After drying the beads are cooled, preferably to 100 F. to 140 F. and then are air-lifted to storage or a packing station. The air-lift air temperature is kept warm and the air rate is as low as feasible to minimize breakage of particles.

The product obtained at the packing station or air-lift outlet is substantially in hollow globule form but is strong enough to resist crushing or pulverizing during normal handling and converting operations. Product of the same formula made according to previous methods employed is either too light or is dusty and contains 50% or more of broken beads. It may be considered as genuinely surprising that a process has been discovered which is suited to produce consistently satisfactory stable product over a range of apparent densities in either countercurrent or concurrent spray towers.

With a detergent composition of specified active in gredient content it has been found that product bulk density may be increased, without loss of stable bead structure, by raising spraying pressure, improving degasification, decreasing mix viscosity, raising mix solids content, adding sodium chloride or by any combination of these changes, within the process limitations. Conversely, density can be decreased by changes in the opposite directions.

The following specific examples are further illustrative of the present invention in its various aspects but the invention is not to be limited thereby. All amounts or percentages throughout this specification and in the claims are by weight unless otherwise indicated.

Example I A synthetic detergent composition in bead form was made by spray drying a 61% solids aqueous crutcher mix to a product of the formula.

Percent Sodium dodecyl benzene sulfonate 40.8 Sodium sulfate (by difference) 48.7 Sodium chloride 7.0 Sodium tripolyphosphate 2.0 Moisture 1.5

A high solids content crutcher mix of the composition indicated above was made at about 120 Fahrenheit. After mixing for about 20 minutes it was deaerated in a Versator at 17 inches mercury absolute pressure, comminuted to a size less than 3.2 millimeters so it would pass a 3.2 millimeter sp-ray nozzle orifice and then heated to 150 Fahrenheit and pumped at 800 pounds per square inch through five 3.2 millimeter diameter orifices into a countercurrent spray tower. The hollow cone spray pattern obtained resulted from whirling the mix in the nozzle block before atomization through the thin sharpedged orifice.

Using drying air at 650 Fahrenheit inlet and 225 Fahrenheit outlet temperatures there was produced a .42 gram per cubic centimeter product at the rate of 10,000 pounds per hour. The product was cooled to a temperature of 100 Fahrenheit to 140 Fahrenheit and was airlifted with warm air at about 120 Fahrenheit to a packing station. It contained to beads and less than 10% of material which passed a No. sieve, and less than 1% through a No. 325 sieve. The free flowing, nontacky product resulting was attractive in appearance and was dust-free compared to previously made sprayed detergent product of essentially the same formula. In subsequent work it was found that sodium chloride content could be varied and also that sodium silicate and additional sodium tripolyphosphate could be used in replacement of the sodium sulfate.

Example 2 Using a countercurrent commercial spray tower there was produced an alkyl aryl sulfonate-sodium sulfate detergent composition containing approximately 40% of the active organic detersive ingredient and 60% sodium sulfate. In this process a crutcher mix was made comprising 50.7% solids and 49.3% water. This slurry included fluid detergent base comprising sodium higher alkyl benzene sulfonate having a tetrameric propylene alkyl group with sodium sulfate, resulting from neutralization of the detergent and sulfona-ting acids by caustic soda. Additional sodium sulfate was added to the aqueous detergent base to obtain a mixture which would be approximately 40% active ingredient on a solids basis.

The crutcher was agitated for about 20 minutes, care being taken that the agitation should not be strong enough to entrain air with the mix. The mix was then raised to 150 Fahrenheit and pumped by a Triplex pump at a pressure of 600 pounds per square inch through a manifold to five nozzles evenly distributed about the top of the spray tower. These nozzles were equipped with thin sharp-edged orifices of /8 inch or 3.2 millimeters diameter and the spray issued from them in hollow cone patterns. In other experiments the installation of a comminutor in the line before the nozzles safeguarded against blocking of the orifice and removed larger undissolved particles from the slurry. A deaerator of the Versator type before the heater enabled the production of a more consistent product of little variation in bulk density from that desired. The sprayed crutcher mix emerged into drying gas which had entered the tower at 640 Fahrenheit and exited at 235 Fahrenheit.

The spray dried detergent beads resulting were cooled at the bottom of the tower by contact with the comparatively cold wall of the cone and by the air near the con veyor which delivers it to an air-lift. At a temperature of 100 to Fahrenheit the product was air-lifted to a packing station where it was filled into drums. At this point the dried beads were tested for bulk density by the standard manufacturing control method. The product s,055,es5

was consistently at about .20 gram per cubic centimeter, ranging from .17 to .23 gram per cubic centimeter and was substantially all, over 80%, in head form, as distinguished from broken particles. The head structure was substantially globular, strong enough to resist breakage in handling. The content of fines was very low, averaging less than 8% through a 100 mesh sieve and less than 1% through 325 mesh.

Example 3 A crutcher mix containing 53% solids was made according to the following formula:

Pounds Detergent base, sodium alkyl aryl sulfonate slurry 1 (containing 31% active ingredient, 23% sodium sulfate and 46% water) 3570 Water 640 Sodium sulfate 735 Pentasodium tripolyphosphate 55 Recycled aqueous detergent (containing 53% sodium alkyl aryl sulfonate and inorganic salt, 47%

water) 1150 Sulfuric acid 20 Antioxidant .8

1 Sodium propylene tetramer benzene sulfonate.

The above components were mixed together at a temperature of 120 Fahrenheit in the following order: detergent base, water, recycled aqueous detergent, sodium sulfate, antioxidant, sodium tripolyphosphate and sulfuric acid. The polyphosphate and acid were added to regulate pH of the product and to buffer it at about pH 7.

Before spraying the temperature of the mix was raised in the drop tank and tower manifold heat exchanger to 150 Fahrenheit. After mixing for approximately 20 minutes and before spraying the mix was deaerated in a Versator, which subjects thin films f the slurry to vacuum, in this case 8 inches mercury absolute. The deaerated and heated spray mixture, containing dissolved, micellar and undissolved components in small particle form, was pumped at a pressure of 800 pounds per square inch gage through 8 spray nozzles located about the upper periphery of the spray tower, each of which was equipped with a thin sharp-edged orifice of inch or 2 millimeters diameter. The spray nozzle blocks were so constructed to impart to the mix a whirling action about the nozzle and orifice axis so as to assist break-up of the spray. When sprayed through the small orifices the mix formed multiple hollow cone spray patterns in the drying chamber. The tower was operated concurrently with the inlet drying gas at 570 Fahrenheit and the exit air temperature at 270 Fahrenheit.

Under these operating conditions spraying was continued for approximately 6 hours at the rate of about 10,000 pounds of solid product sprayed per hour or 3 crutcher batches per hour. The detergent beads sprayed during this time were continuously examined and tested. Apparent bulk density, measured according to Standard Practice Instructions, was kept between about .16 and .20, with an average of about .17 gram per cubic centimeter. If desired this figure can be raised by replacement of sodium sulfate with as little as 3 to 15% sodium chloride, the replacement being weight for weight. The .17 density product made according to the above formula and method was substantially composed of globular particles, over 85 on the average being in such form at the outlet from the air-lift. At some times the percentage of globular particles rose as high as 95% for considerable periods.

In other tests applied to the sprayed detergent it was found to contain little dust or fines, all passing through a 20 mesh screen and over 90% remaining on a 100 mesh screen, over 98% on one of 325 meshes. The active organic detergent percentage was from 38 to 42%, showing that there was no segregation in the processing equipment. The product passed standard tests for lack of tack- '8 iness, was free flowing, non-dusting and of attractive size and shape.

Example 4 A particulate detergent of high organic detergent content was made according to the following composition:

Percent Sodium higher alkyl benzene sulfonate (the alkyl being a polymeric lower alkene containing 12 to 15 carbon atoms) 77.7 Sodium sulfate 11.1 Sodium silicate (Na O/SiO =1/2.35) 9.8 Antioxidant .02 Moisture 1.4

A crutcher mix of the above constituent was mad at 52% solids content and at 120 Fahrenheit. It had a viscosity of about 9,000 centipoises. After additional mixing in a Patterson mixer, it was sprayed at 600 pounds per square inch and later for a longer period at 1100 pounds per square inch gage through a pair of spray nozzles, of inch and inch diameter respectively, into a concurrent drying tower. The drying tower inlet air was at 540 Fahrenheit and the outlet air was at 265 Fahrenheit. Spraying was at the rate of about 2,000 pounds solids per hour.

Examination of the detergent produced showed that it was over 75% by weight in bead or globule form and that substantially all was between .075 and .85 millimeter diameter when sprayed at 1100 pounds per square inch. As the spray pressure was increased the particle size increased.

The product was dry and non-tacky and was found to be satisfactory for converting into special detergents when it was compounded and built. It could be air-lifted and handled without change in its bulk density of .32 gram per cubic centimeter.

The above invention has been described with particular reference to certain examples of processes in which it has been embodied. It Will be obvious to one of skill in the art that modifications may be made in the processes that have been illustrated and described and equivalents may be substituted for elements thereof without departing from the spirit of the invention or going beyond the scope of the claims.

What is claimed is:

1. A process for drying detergents which consist essentially of a mixture of 10 to of sodium alkyl benzene sulfonate detergent in which the alkyl group is of 12-18 carbon atoms and to 20% of water soluble inorganic salt selected from the group consisting of sodium sulfate, sodium chloride, pentasodium tripolyphosphate, sodium silicate, and mixtures thereof, the ratio of organic detergent to inorganic salt employed being such as to allow production of a non-tacky composition as non-dusting, free flowing, stable particles which resist breakage during handling and are substantially all beads of substantially globular shape with diameters within the range of .075 to .85 millimeter and of bulk density from .16 to .50 gram per cubic centimeter, which comprises making an aqueous crutcher mix containing 40 to 65% of the synthetic organic detergent and inorganic salt and 60 to 35% water, substantially free of entrained gases, heating the mix to a temperature of to 210 Fahrenheit, spraying the mix at a pressure of 500 to 1500 pounds per square inch through an orifice of diameter between 2.0 and 3.2 millimeters in a conical spray pattern into heated drying gas, drying the sprayed particles to a form retaining, substantially globular, particulate product of low moisture content and cooling the particles to a temperature at which they will be non-tacky and non-agglomerative.

2. A process for drying detergents which consist essentially of a mixture of 10 to 80% of sodium alkyl benzene sulfonate detergent in which the alkyl group is of 12 to 18 carbon atoms, and 90 to 20% of water soluble inorganic salt selected from the group consisting of sodium sulfate, sodium chloride, pentasodium tripolyphosphate, sodium silicate, and mixtures thereof, the ratio of organic detergent to inorganic salt being such to allow production of a non-tacky composition as non-dusting, free flowing, stable particles which resist breakage during handling and are substantially all beads, over 75%, of substantially globular shape with diameters of .15 to .85 millimeter and of bulk density of .20 to .50 gram per cubic centimeter, which comprises making an aqueous crutcher mix containing 40 to 65% of the synthetic organic detergent and inorganic salt and 60 to 35% water, removing entrained and dissolved gases by subjecting the mix to a reduced pressure of less than 20 inches of mercury, absolute, heating the mix to a temperature of 120 to 210 Fahrenheit, spraying the mix at a pressure of 500 to 1500 pounds per square inch through a spray nozzle having a thin sharp-edged orifice of diameter between 2.0 and 3.2 millimeters in a hollow conical spray pattern into drying gas at a temperature of 200 to 650 Fahrenheit; drying the sprayed particles to a form retaining, substantially globular product of less than moisture content and cooling the particles to a temperature at which they will be non-tacky and non-agglomerative.

3. A process for drying detergents which consist essentially of a mixture of to 80% of sodium alkyl benzene sulfonate detergent in which the alkyl group is of 12 to 18 carbon atoms, and 90 to 20% of water soluble inorganic salt selected from the group consisting of sodium sulfate, sodium chloride, penta-sodium tripolyphosphate, sodium silicate, and mixtures thereof, the ratio of organic detergent to inorganic salt employed being such to allow production of a non-tacky composition as non-dusting, free flowing, stable particles which resist breakage during handling and are substantially all beads, over 75%, of substantially globular shape with diameters of .15 to .85 millimeter and of bulk density of .20 to .50 gram per cubic centimeter, which comprises making an aqueous slurry crutcher mix containing 40 to 65% of the synthetic organic detergent and inorganic salt and 60 to 35% water, removing entrained and dissolved gases by subjecting thin films of the mix to a reduced pressure of less than 20 inches of mercury, absolute, comminuting the mix so that all the hard, unyielding particles therein have no dimension larger than the spray orifices, heating the mix to a temperature of 120 to 210 Fahrenheit, spraying the mix at a pressure of 500 to 1500 pounds per square inch through a spray nozzle having a thin sharpedged orifice of diameter between 2. 0 and 3.2 millimeters in a hollow conical spray pattern into a chamber containing flowing drying gas at a temperature of 200 to 650 Fahrenheit, drying the sprayed particles to a form retaining, substantially globular product of less than 5% moisture content, cooling the particles to a temperature at which they will be non-tacky and non-agglomerative, withdrawing the particles at the bottom of the chamber and elevating them by means of an air-lift to an upper level from which they may be fed to a packing station.

4. A process for drying detergents which consist essentially of a mixture of 30 to 50% of sodium alkyl benzene sulfonate detergent in which the alkyl group is a polymer of lower alkene, having a branched chain of 12 to 15 carbon atoms, and to 50% of water soluble inorganic salt selected from the group consisting of sodium sulfate and mixtures of sodium sulfate with sodium chloride, the ratio of organic detergent to inorganic salt employed being such to allow production of a non-tacky composition as non-dusting, free flowing, stable particles which resist breakage during handling and are substantially all, over of substantially globular shape with diameters of .15 to .85 millimeter and of bulk density of .20 to .50 gram per cubic centimeter, which comprises making an aqueous slurry crutcher mix containing 40 to 65% of synthetic organic detergent and inorganic salt and 60 to 35% water, removing entrained and dissolved gases by subjecting thin films of the mix to a reduced absolute pressure of less than 10 inches of mercury, comminuting the mix so that all the hard, unyielding particles therein have no dimension larger than the spray orifices, heating the mix to a temperature of 140 to 200 Fahrenheit, spraying the mix by imparting to it a whirling motion within a spray tip and then atomizing it at a pressure of 500 to 1,000 pounds per square inch through a plurality of nozzles having thin, sharp-edged orifices of diameters between 2.0 and 3.2 millimeters in a multiple hollow cone spray pattern into a chamber containing flowing drying gas at a temperature of 200 to 650 Fahrenheit, drying the sprayed particles to a form retaining, substantially globular product of less than 5% moisture content, cooling the particles to a temperature between and Fahrenheit at which they will be non-tacky and non-agglomerative, withdrawing the particles at the bottom of the chamber and elevating them by means of an air-lift with air at a temperature of 100 to 140 Fahrenheit to an upper level whence they may be fed to a packing station.

References Cited in the file of this patent UNITED STATES PATENTS 2,364,767 Zizinia et al Dec. 12, 1944 2,606,156 Davis Aug. 5, 1952 2,798,544 Davis July 9, 1957 2,889,283 Tecklenburg June 2, 1959

Claims

1. A PROCESS FOR DRYING DETERGENTS WHICH CONSIST ESSENTIALLY OF A MIXTURE OF 10 TO 80% OF SODIUM ALKYL BENZENE SULFONATE DETERGENT IN WHICH THE ALKYL GROUP IS OF 12-18 CARBON ATOMS AND 90 TO 20% OF WATER SOLUBLE INORGANIC SALT SELECTED FROM THE GROUP CONSISTING OF SODIUM SULFATE SODIUM CHLORIDE, PENTASODIUM TRIPOLYPHOSPHATE, SODIUM SILICATE, AND MIXTURES THEREOF, THE RATIO OF ORGANIC DETERGENT TO INORGANIC SALT EMPLOYED BEING SUCH AS TO ALLOW PRODUCTION OF A NON-TACKY COMPOSITION AS NON-DUSTING FREE FLOWING STABLE PARTICLES WHICH RESIST BREAKAGE DURING HANDLING AND ARE SUBSTANTIALLY ALL BEADS OF SUBSTANTIALLY GLOBULAR SHAPE WITH DIAMETERS WITHIN THE RANGE OF .075 TO 85 MILLIMETER AND OF BULK DENSITY FROM .16 TO .50 GRAM PER CUBIC CENTIMETER, WHICH COMPRISES MAKING AN AQUEOUS CRUTCHER MIX CONTAINING 40 TO 65% OF THE SYNTHETIC ORGANIC DETERGENT AND INORGANIC SALT AND 60 TO 35% WATER, SUBSTANTIALLY FREE OF ENTRAINED GASES, HEATING THE MIX TO A TEMPERATURE OF 120* TO 210* FAHRENHEIT, SPRAYING THE MIX AT A PRESSURE OF 500 TO 1500 POUNDS PER SQUARE INCH THROUGH AN ORIFICE OF DIAMETER BETWEEN 2.0 AND 3.2 MILLIMETERS IN A CONICAL SPRAY PATTERN INTO HEATED DRYING GAS, DRYING THE SPRAYED PARTICLES TO A FORM RETAINING, SUBSTANTIALLY GLOBULAR, PARTICULATE PRODUCT OF LOW MOISTURE CONTENT AND COOLING THE PARTICLES TO A TEMPERATURE AT WHICH THEY WILL BE NON-TACKY AND NON-AGGLOMERATIVE.