Back to results
US 4,832,700 AGranted
Process and apparatus for preparing dust-free granular material
AssigneeSandoz Ltd.
InventorsJan Kaspar, Pierre Schmid
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeSandoz Ltd.
InventorsJan Kaspar, Pierre Schmid
Estimating the term…
A fluidized bed apparatus comprises a chamber having a perforated floor, a spray nozzle located in the chamber above the perforated floor, whereby material to be granulated is introduced into the chamber in the form of a solution or dispersion, means for passing heated gas upward through said perforated floor, whereby solid particles of said material are formed in said chamber, particle size-reducing means outside of said chamber, whereby particles larger than a first predetermined size are reduced in size, a screw shaft located above said perforated floor and communicating with said size-reducing means, whereby particles are withdrawn from said chamber and conveyed to said size-reducing means, a pipe having one end located downstream of said size-reducing means and its other end communicating with said chamber, and means for generating a flow of air whereby particles smaller than a second predetermined size exiting from said size-reducing means are returned through said pipe to said chamber.
A process for preparing a granular product having particles of a size substantially within the range from a first predetermined larger size to a second predetermined smaller size comprising the steps of (1) introducing the material to be granulated in the form of spray of a solution or dispersion to a fluidized bed drier, (2) removing solid particles formed in the fluidized bed from the fluidized bed, (3) passing all of the removed particles through means whereby all the removed particles larger than said first predetermined size are reduced in size and (4) contacting the particles after passing through the size reducing means and while falling therefrom with air flowing countercurrent to the fall of the particles at such a force as to cause substantially only the particles smaller than said second predetermined size to move in a direction opposite to their fall and to be returned to the fluidized bed drier.
Dependencies are inferred from the claim text.