CA1134800A - Densified small zeolite particles - Google Patents

Abstract

DENSIFIED SMALL ZEOLITE PARTICLES
Abstract Small aluminosilicate particles are densified by drying them with small amounts of certain inorganic salts. Subsequent handling increases or maintains density rather than resulting in a decrease of density as with the aluminosilicate particles.

Description

DENSIFIED SM~LL ZEOLITE PARTICLES
Samuel M. Johnson Technical Field This invention relates to "densified" aluminosilicate particles. Certain aluminosilicates (zeolites) are usefu1 as detergency builders when in finely divided form. However, finely divided aluminosilicates are very bulky and when they are handled, their density decreases.
Disclosure of the Invention This invention is based upon the discovery that small (0.01-25 microns) zeolite particles which have been washed free or substantially free of extraneous water-soluble inorganic materials for use as detergency builders can be densified and/or their bulk densi~y maintained by drying them, preferably spray-drying them, in the presence of from about 1% to about 20% of certain inorganic salts which are compatible with a detergent product. The inorganic salts must be on the outside of the zeolite particles to be effective.
More specifically, this invention relates to the discovery of: a process for increasing the compressed bulk density of a particulate aluminosilicate having an average particle size of from about O.Ol micron to about 25 microns comprising the steps of (a) preparing an aqueous slurry containing from about 30~ to about 60% of the particulate aluminosilicate and containing from about 1% to about lO~ of a water soluble salt selected from the group consisting of sodium or potassium sulfate, chloride or carbonate or mixtures thereof, said slurry being essentially free of organic detergent surfactants and (b) drying said slurry to form a particulate aluminosilicate which maintains a higher compressed density than that of the original aluminosilicats.
Detailed Description of the Inv ntion The Aluminosilicate The aluminosilicates of this invention comprise zeo-lites having a particle size defined hereinbefore, and .... ~ . ,- .

, -~ . J*

1~3~800 having detergency builder capability. Preferred zeo-lites are zeolites A, X and P (s) which have not been dehydrated and which contain at least about 10~ up to fuLl saturation of water of hydration.
Particle size of the aluminosilicate is from about 0.01 micron to abou-t 25 microns, preferably from about 0.1 micron to about 10 microns, and more preferably from about 1 micron to about 5 microns. Preferably these aluminosilicates will not have been previously dehydrated below about 10% water of hydration. This particle size is an overall particle size and refers to the gross particles whether it is an individual crystal or an agglomerate of individual crystals. The slurry will contain from about 30% to about 60% aluminosilicate, preferably from about 35% to about 50~.
The alumino ilicates that are suitable for use in this invention include specifically those described in U.S. Patents 3,985,669 (Krummel et al) for Detergent Compositions; and U.S. Patent 4,000,094 (Krummel et al) for Water-Insoluble Aluminosilicate Containing Detergent Composition~

The Inorganic Salt The inorganic salts which can be used in the practice of this invention include sodium 2nd potassium sulfates, chlorides and carbonates and mixtures thereof.
Preferably the sodium salts are used and preferably either the carbonate or the sulfate salts are used since they are normally present in detergent compositions and are less prone to cause corrosion problems than the chloride salts. Carbonates provide a builder fun~tion as well. Preferably the amount of salt in the slurry to be dried is from about 1% to about 6%, preferably from about ~.5~ to about 3~. These smaller amounts provide the benefit without diluting the aluminosilicate.
The benefits of the process and product of this invention are many. The aluminosilicate has to be dried for shipment e~onomy so there is essentially no ~134800 extra cost involved in adding the organic salt. There is usually an immediate increase in density beyond what would be expected by accounting for the contribution of the density increase of the salt alone and a corres-ponding reduction in bulk. Surprisingly the density isoften increased upon handling and is always maintained be.ter than the density of zeolite not containing salt.
Small particle aluminosilicates which have not been densified according to this invention tend to lose density upon attrition, e.g. handling. However, the compositions of this invention upon attrition by handling, etc., often actually increase in bulk and storage density. Higher density allows more product to be shipped in a given container and simplifies loading, unloading, and storage of aluminosilicates, e.g., their pending incorporation into detergent compositions.
~he Drying Process The slurry of aluminosilicate and inorganic salt can be dried in any conventional way. Spray-drying is preferred. Other processes include drum drying and freeze-drying. Drying temperatures must be adjusted to achievq product moisture between 15%-25~.
All parts, percentages, and ratios herein are by weight unless otherwise specified.
The following example illustrates the practice of this invention.
EXAMPLE
The following slurries were prepared by mixing the indicated ingredients in a conventional detergent crutcher and spray-drying in a 10' diameter spray tower with an inlet temperature of about 200-250C. at a rate of about 20-30 pounds of slurry per minute.
Run 12 3 Component Approximate %
35Anhydrous zeolite A 77.4 7574.5 (3.2 micron average particle diameter) Na2SO4 (anhydrous) 3.7 - 7.1

2 3 ~ 3.7 ~ 18.9 21.318.4 ,,,",, .,. .. ...... . .. , ., . ,.. . ... ~

~13~800 - 4 ~

These products were tested against a control containing only the Zeolite A by a~itating the products in a standard way for about 20 minutes to simulate the normal handling of the zeolite and then applying pressure for 20 minutes to simulate what would occur during loading of the zeolite in a rail car. The bulk density under compression before and after agitation shows that, surprisingly, the products of the invention maintain a higher density, or increase it, while under compression whereas the untreated Zeolite A actually loses density under treatment.
Density under compression Run Before Agitation After Agitation 1 41 45.5 2 38 40.0

3 43.5 42.5 Control 45 34 (Untreated Zeolite A) With the invention, more net pounds of zeolite can be shipped in each container, e.g., freight car. The ability of small amounts of the water-soluble salts to e~fect the density favorably is essential, since the water soluble salt is simply a diluent when one is shipping the zeolite.
Similar results are obtained in that the treated, compressed density of the aluminosilicate is increased when NaCl, ~Cl, K2SO4, and/or K2CO3 are substituted on an equal weight basis for part or all of the Na2SO4 and/or Na2CO3 and/or hydrated Zeolites X and/or hydrated Zeolite P are substituted on an equal weight basis for part or all of the Zeolite A.

, WHAT IS CLAIMED IS:

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Claims (12)

Claims:

1. A densified aluminosilicate composition having a particle size of from about 0.01 micron to about 25 microns, containing from about 2 to about 10% by weight of an inorganic salt selected from the group consisting of sodium and potassium sulfates, chlorides and carbonates and mixtures thereof external to the aluminosilicate particles, said aluminosilicate capable of maintaining a compressed bulk density in excess of about 35 pounds per cubic feet under static head exceeding 1 lb./in2, said composition being essentially free of organic detergent surfactants and said aluminosilicate contains at least about up to 10% full saturation of water of hydration.

2. The composition of Claim 1 wherein the aluminosilicate is selected from the group consisting of Zeolites A, X and P and mixtures thereof which contain from about 10% to about saturation of water of hydration.

3. The composition of Claim 2 wherein the zeolite is Zeolite A.

4. The composition of Claim 1 wherein the inorganic salt is at a level of from about 3% to about 6% and the salt is selected from the group consisting of sodium sulfate, sodium carbonate and mixtures thereof.

5. The composition of Claim 4 in which the zeolite is Zeolite A.

6. A process for increasing and/or maintaining compressed bulk density of a particulate aluminosilicate having an average particle size of from about 0.01 micron to about 25 microns comprising the steps of:
(a) preparing an aqueous slurry containing from about 30% to about 60% of the particulate aluminosili-cate and containing from about 1% to about 6% of a water-soluble salt selected from the group con-sisting of sodium or potassium sulfate, chloride, carbonate or mixtures thereof, said slurry being essentially free of organic detergent surfactants;
and (b) drying said slurry to form a particulate alumino-silicate which maintains a higher bulk density under pressure than that of the original aluminosilicate.

7. The process of Claim 6 wherein said slurry is spray-dried.

8. The process of Claim 6 wherein said aluminosilicate is selected from the group consisting of hydrated Zeolites A, X, P and mixtures thereof.

9. The process of Claim 6 wherein said water-soluble salt is selected from the group consisting of sodium or potassium sulfate, carbonate and mixtures thereof.

10. The process of Claim 9 wherein said water-soluble salt is a carbonate.

11. The process of Claim 6 wherein the slurry contains from about 35 to about 50% aluminosilicate and from about 1.5 to about 3% of water-soluble salt.

12. The composition of Claim 2 containing from about 15%
to about 25% by weight of water.