GROWTH REGIME MAP FOR LIQUID-BOUND GRANULES

A regime map of granule growth behavior is proposed based on granule d eformation during collision and the granule liquid content measured as the maximum pore saturation. The granule deformability on collision i s represented by a deformation number, which is a ratio of granule imp act energy to the plastic energy absorbed per unit strain. Granule gro wth regimes such as steady growth, induction, nucleation, crumb and sl urry are defined. This regime map qualitatively explains the variation s in granulation behavior. Laboratory drum granulation experiments wer e used to test the regime map. Experiments were performed in a 0.3-m-d ia, drum using three sizes of glass ballotini (19, 31, and 60 mu m) wi th water and glycerol as liquid binders. Increasing granule yield stre ss by decreasing particle size and increasing binder viscosity caused the system to move from steady growth to induction behavior as predict ed by the regime map. Preliminary validation with literature data was also encouraging. More work, however, is required to better quantify t he boundaries between different growth regimes and to investigate the effect of process agitation intensity. This regime map has great poten tial to help design and control granulation systems, because it is bas ed on properties of the powder/binder system that can be measured or e stimated without performing any granulation tests.