Spray Granulation

Fluid bed spray granulation produces dense particles by layering solids from a suspension, solution or melt onto nuclei created as a spray-dried by-product of the atomized spray liquid or abrasion from larger particles or on starter nuclei inserted as a defined quantity. For this processing option the liquid only serves as a vehicle for the solid particles contained in the spray liquid.

This process would be rather lengthy in a batch type fluid bed, unless process ramps are introduced:

•  Produce spray-dried powders by spraying the liquid at a high temperature
•  Agglomerate the powders by means of the agglomeration technique
•  Layer the majority of the liquid on the such produced nuclei

More often, this processing option is used in a continuous fluid bed system with air-classifying discharge, as the creation of nuclei and discharge of the right size granules will then occur in a self-regulating equilibrium. With this processing technique the usual finished particle size can range from 0.2 – 5.0 mm.