Coating processes – Measuring – testing – or indicating
Patent
1988-05-05
1990-01-23
Lusignan, Michael
Coating processes
Measuring, testing, or indicating
118303, 118712, 118DIG5, 427213, B05D 1700, B05D 700, B05C 500, B05C 1100
Patent
active
048957330
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
The invention refers to a method for agglomerating particles and/or for coating particles, in particular for coating particles with other particles, in which method the particles are moved by the rotation of a rotor disc.
The invention furthermore refers to a system for agglomerating particles and/or for coating particles, in particular for coating them with other particles, the system comprising a vessel, a rotor disc rotatably supported within the vessel for moving the particles, and a drive device operatively connected, for rotation, with the rotor disc and serving for rotating the same.
Methods and systems of this kind may be used, for example, for producing particulate drugs or components of drugs, furthermore of nutrients, agricultural and other chemicals, seed pellets, as well as metallic granules subjected subsequent to their granulation to an additional sintering process, for producing catalytic materials.
THE STATE OF THE ART
U.S. Pat. No. 4,323,312 discloses fluidized bed granulators comprising a vessel having a vertical central axis, a rotor disc supported for rotary movement around said axis, a drive device to rotate the rotor disc and a blower. The agglomeration of a particulate material in a system of this kind is accomplished by moving the particles within a processing space disposed above the disc, by the rotation of the disc and by passing air therethrough. During the process, the particles momentarily on the disc are caused to roll outwardly, toward the edge of the disc, here they are lifted upward by the air stream and are caused to drop back onto the disc.
In actual practice, the particulate material is often introduced into the vessel in dry form and is humidified in the same by a liquid containing water, the liquid being sprayed into the vessel by means of a spraying nozzle not disclosed in U.S. Pat. No. 4,323,312. The particles generated by agglomeration during the supply of the liquid are subsequently allowed to dry in the processing space, while no liquid is supplied. Various properties of the particles generated by granulation, in particular their geometrical and mechanical properties, as their shapes and mean sizes, the standard deviations of the particle sizes and their porosity, as well as the abrasive resistance of the particles, are dependent primarily on the liquid content of the particles during the termination phase of the granulation process, but also on other parameters of the method. When agglomerating a batch of a particulate material, for example, in the beginning only initially provided particles can become deposited on each other, and on particles previously agglomerated. If now the total quantity of liquid supplied exceeds a specific value, then relatively large particles previously agglomerated can also become deposited on each other, so that twin particles or triplets, etc. can form, the particle shapes become very irregular and the particle sizes increase rapidly ad discontinuously. The liquid content of the particles evidently depends upon the quantity of the sprayed or injected liquid per unit mass of dry particulate material, but also upon the humidity of the air introduced into the vessel, and upon the quantity of liquid removed by this air from the particulate material in the form of steam and/or suspended droplets. If the air introduced into the vessel is drawn, at least in part, from the surroundings, then its humidity content may vary depending upon the humidity content of the surrounding air, and influence the properties of the product. Therefore, particularly if granulated materials are industrially produced and if sizeable batches of such materials are produced repetitively, it is frequently not perfectly possible to produce granulated particles having desired properties, as for example spherical shapes and uniform sizes, by preference. It is equally known in the field, to condition he air supplied to the vessel prior to its being introduced thereinto, i.e. to bring it to a predetermined small remaining humidity c
REFERENCES:
patent: 4323312 (1982-04-01), Glatt et al.
patent: 4344747 (1982-08-01), Henry
patent: 4644665 (1987-02-01), Naunapper et al.
"Monitoring Granulation", H. Leuenberger, Manufacturing Chemist, Jun. 1984, pp. 53, 55.
Bericht uber das 4, Interdisziplinare Symposium Agglomeration, Toronto/Kanada of Jun. 2-5, 1985, Swiss Pharma, 7, 1985, pp. 13, 14, 16, 17.
"Determination of the Uncritical Quantity of Liquid by Power Measurements on Planetary Mixers", H. P. Bier, H. Leunberger and H. Sucker, Pharm. Ind. 41, No. 4, 1979, pp. 375-380.
"Granulation, New Techniques", H. Leuenberger, Pharm. Acta Helv., 1982, No. 3, pp. 72-82.
"Monitoring Granulation", H. Leuenberger, Manufacturing Chemist, May 1984, pp. 67, 69, 71.
Imanidis Georgios
Leuenberger Hans
Nowak Reinhard
Studer Jurg M.
Winzap Stefan
Lusignan Michael
Pharmatronic AG
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