PRESSURE SWING GRANULATION, A NOVEL BINDERLESS GRANULATION BY CYCLIC FLUIDIZATION AND GAS-FLOW COMPACTION

Pressure swing granulation, a novel fluidized bed binderless granulation method for fine cohesive powders, was developed. In this method the fine powders were agglomerated and fluidized smoothly by cyclic fluidization and downward air flow compaction. Spherical granules were obtained. The size range of the product granules from this method is 0.1-1 X 10(-3) m in diameter which so far has been difficult to attain by conventional spray drying and fluidized bed granulation. The diameter and the bulk density of granules increased with increasing superficial gas velocity and bed height. The bulk density also increased with increasing compaction pressure. The compression strength of a single granule was determined by a micro compression testing machine. The granules showed reasonable strength to survive during transportation and storage with reasonable fragileness to disintegrate under small forces.