Solid material comminution or disintegration – Processes – With application of fluid or lubricant material
Reexamination Certificate
1999-10-29
2002-03-19
Ostrager, Allen (Department: 3725)
Solid material comminution or disintegration
Processes
With application of fluid or lubricant material
C241S024110
Reexamination Certificate
active
06357678
ABSTRACT:
BACKGROUND
A need has arisen for a process capable of producing ultra finely-divided synthetic zeolite powder for use in the production of detergent powder compositions and as a thermal stabilizer and/or blocking agent for certain polymer compositions.
Generally speaking, there are two approaches for producing synthetic zeolites of small particle size. One approach is to synthesize the zeolite in a very dilute aqueous medium. Unfortunately, attempts to recover the finely-divided zeolite product by removing the water from the aqueous medium have proven unsuccessful. Under the conditions used, the finely-divided zeolite particles agglomerated thereby producing a product of undesirably large, average particle size.
The other method involves physical subdivision of preformed particulate zeolite by use of milling procedures. Because of the relative low density of zeolites, the only known feasible method for effecting such subdivision has been ball milling of the zeolite in water containing a substantial amount of a dispersant. See in this connection McLaughlin, U.S. Pat. No. 5,704,556. Unfortunately, it was not possible to recover the finely-divided zeolite from the aqueous medium of the McLaughlin patent without experiencing substantial agglomeration of the particles. In fact, attempts to effect such separation have resulted in formation of zeolite particles having an average particle size larger than the zeolite as it existed prior to ball milling. In addition, the presence of the dispersant almost always leaves undesirable residues in the recovered product rendering it unsuitable, without further purification, for certain end use applications.
Japan kokai 01-153514, laid open on Jun. 15, 1989, describes formation of “submicron” A-type zeolite by a forming an aqueous solution from aluminum hydroxide and sodium hydroxide at 35° C. or less. A second aqueous solution of colloidal silica is formed, again at 35° C. or less. These solutions are mixed at 35° or less with agitation for a period of time (e.g., 5 hours) for nuclei to form, and the resultant slurry is then agitated for 24 hours at 35-38° C. for crystal growth to occur. It is indicated that the maximum particle size of the zeolite formed in this manner is 0.4 micron or less. However, the particle size of zeolite as reported by the kokai was determined by SEM (Scanning Electron Microscope, see Table 1, thereof) which is useful in determining the particle size of zeolite crystals, but not useful in determining the size of particles. The difference is that each particle consists of several zeolite crystals (or zeolite crystal particles). The particle size defined hereinafter is the size of particles determined under a dispersed state.
In sum, when using an electron microscope, one can distinguish the boundary of crystals, hence the crystal size. But one cannot distinguish particle boundary which is necessary for zeolite particle size determination.
Furthermore, to conduct a process such as described in the kokai, it is not possible to use as the starting material synthetic zeolite produced in existing plant facilities. Thus one or more conventional zeolite products plus the zeolite product of the kokai cannot be produced in an existing plant using conventional zeolite synthesis technology. Instead, to use the process of the kokai either new synthesis facilities are required, or the normal operation of the existing synthesis facilities, if adaptable for use in conducting the special process of the kokai, must be interrupted so as carry out such special process.
BRIEF SUMMARY OF THE INVENTION
This invention is deemed to provide an effective and efficient way of circumventing all of the foregoing difficulties whereby isolatable ultra fine synthetic zeolite powder can be effectively produced from synthetic zeolite that has been produced using conventional synthesis technology. New synthesis plant facilities are unnecessary. And the operation of existing synthesis plant facilities need not be interrupted in order to form finely-divided zeolite powder. Instead, the synthesis process can be carried out at the same time special finely-divided synthetic zeolite is being formed from conventional synthetic zeolite already produced. Moreover, the equipment required for conducting the process technology of this invention is readily available for purchase, if not already available at plant site. Moreover, finely-divided zeolite powder with true ultra-fine particle size are produced. Particle size is not determined by SEM, and thus erroneous particle size determinations are not obtained or utilized.
In accordance with one of its embodiments, this invention provides a process for producing ultra-finely divided synthetic zeolite which comprises micronizing particulate synthetic zeolite in an inert or substantially inert liquid organic medium that is devoid or substantially devoid of water, and devoid of dispersant, to form a micronized zeolite product having an average particle size of about 2 microns or less and containing at least 90% by weight, based on the total weight of the zeolite product (i.e., the weight of the zeolite solids if removed from the organic medium and dried), of particles no larger than about 5 microns. In other words, the weight percentage of the micronized zeolite product that fulfills this requirement of having an average particle size of about 2 microns or less is based on the dry weight of the zeolite product, as if it were in isolated form.
Another embodiment of this invention is a dry, finely-divided synthetic zeolite powder having an average (mean) particle size of about 2 microns or less, and containing at least 90% by weight, based on the dry weight of the zeolite product, if isolated, of particles no larger than about 5 microns. In a preferred embodiment, the mean particle size of the dry, finely-divided synthetic zeolite powder is 1 micron or less, and at least 90% by weight of the finely-divided zeolite powder (assuming the powder has been isolated and dried) has a particle size of 2 microns or less. The preferred zeolite in these compositions is zeolite-A, zeolite-X, or zeolite-Y, or a mixture of any two or all three of these. More preferred zeolites are zeolite-A and zeolite-X. Zeolite-A is the most preferred zeolite of this embodiment of the invention.
Still another embodiment is a composition comprising a mixture of (A) finely-divided anhydrous or substantially anhydrous synthetic zeolite having an average (mean) particle size of about 2 microns or less, and containing at least 90% by weight, based on the dry weight of the zeolite product, if isolated, of particles no larger than about 5 microns, and (B) a liquid organic medium. The organic medium constitutes a continuous liquid phase in the mixture. In preferred compositions of this type, the mean particle size of the finely-divided anhydrous or substantially anhydrous synthetic zeolite is 1 micron or less, and at least 90% by weight of such zeolite has a particle size of 2 microns or less. The preferred synthetic zeolite in these compositions is zeolite-A, zeolite-X, or zeolite-Y, or a mixture of any two or all three of these. More preferred zeolites are zeolite-A and zeolite-X. Zeolite-A is the most preferred zeolite for use in the practice of this embodiment of the invention. The synthetic zeolite used in forming these compositions must either be totally anhydrous or, if it contains water, its water content must be below the amount corresponding to the theoretical quantity of water of hydration for that particular zeolite. Preferably the zeolite will contain a total amount of water that is no more than 90 wt% of the theoretical quantity of water of hydration, and most preferably will contain no more than 20 wt% of this theoretical quantity. The water content of the zeolite being used in forming the foregoing compositions should be determined, in any case where the actual water content is not already known, by measuring the weight loss of a sample of such zeolite after the sample has been maintained at 800° C. for 1 hour.
To reduce the total quantity o
Camp Ronald L.
Hu Patrick C.
Langlois, Jr. Conrad J.
Albermarle Corporation
Hong William
Ostrager Allen
Pippenger Philip M.
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