Abstract
A new granulation method using a tumbling fluidized bed granulator equipped with an opposed, pulsed air-jet assembly has been applied to produce microgranules having a size distribution in a region less than 100μm.
The effect of the pulsed air-jet on the properties of the microgranules was investigated, and its growth model was also discussed.
It was confirmed that the microgranules produced by the new method have both a smaller granule size and a larger surface area, as well as better solubility and higher compressibility compared with those of the granules produced by usual tumbling fluidized bed granulation. The microgranule growth mechanism was characterized by the following three steps:
(1) the formation process of smaller granules by the agglomeration of feed particles. The smaller granule size depended on the size of the spray droplets.
(2)the successive coating process of the smaller granules.
(3)the coalescence of the smaller granules into the final microgranules.
