Process advantages
Pellets are manufactured directly and very quickly from a supply
of powder with the addition of a binding agent or solvent. The granules
or pellets produced have a high-density (comparable with granulates
from vertical granulators).
Coatings with a high solid material content can be used, if required.
When layering, the active ingredient can either
a) be sprayed onto a given core in a solution of up to 50%,
b) sprayed as a suspension, or
c) dosed in powder form in conjunction with a solvent and binding
agent.
Very thick film layers can be applied by means of the rotor method.
The increase in weight when layering can be up to 10 times the starting
weight in the rotor.
A further advantage is that the tangential nozzle is always optimally
positioned directly in the product.
Principle of operation
Powder is mixed and moistened in the fluid bed rotor (->
GPCG series with Rotor Insert). With the fluid bed rotor, solvents
or binders are added tangentially.
The powder bed is set into a centrifugal motion by means of the
rotor. A spiral movement of the powder bed occurs due to the process
air, which is fed through a variable air gap along the edge of
the rotor disc.
Agglomerates are formed, which spheronize into uniform and dense
pellets due to the rotation of the rotor disc (->
Direct Pelletizing, ->
Pelletizing by Layering). The speed of rotation has a direct
influence on the density and size of the pellets. The moist pellets
are dried either directly in the rotor during a drying phase with
air fed in at high temperature or in a fluid bed dryer from the
WST/G range.
If required, the systems can be made inert for applications with
organic solvents.
(-> Solvent Recovery)
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