Many raw materials must be converted into a liquid, sprayable form before the process.
In our plants we can mix, disperse, emulsify, heat, cool and, where appropriate, neutralise, or carry out simple chemical conversion reactions immediately before spraying.
The liquid is sprayed through two-component nozzles as fine droplets (diameter 20–50 µm). The droplets enter the air flow of the fluidised bed unit and are dried instantly by the direct and intensive heat transfer. The initial result is very small particles – the so-called seeds. These are held in suspension in the fluid bed (fluidisation) and form a surface to which further continuous atomised droplets stick and dry.
Thus, in the fluidised bed spray granulation process drying takes place coupled with the controllable growth of discrete particles. Dust-free granulates are the result. These can be removed from the reactor flexibly and continuously through a classifying discharge without interrupting the drying process. This offers a flexible choice of particle sizes between 200 and 5.000 µm.
- Spray Dilution
- Granulate Discharge
- Inlet Air
- Outlet Air
- Classifying Air
- Classifying Discharge
Onion-skin and Blackberry Structures
The spray granulation has decisive advantages: Precursors, drying and process can be configured in such a way that the particles produce special morphologies with different properties and characteristics – onion-skin or blackberry structures.
- Easily dosable, dust-free granulates
- Improved dissolution and redispersibility of the granules in water
- Granulates suitable for tablet pressing (direct compression)
- Defined particle size distribution
- Dense surface structure
- Reduced wear
- Reduced hygroscopicity