Exploring the regime map for high-shear mixer granulation

The aim of this study was to investigate the applicability of the regime map approach proposed by Litster/Iveson and co-workers [S.M. Iveson, J.D. Litster, Growth regime map for liquid-bound granules, AIChE Journal 44 (1998) 1510–1518; S.M. Iveson, P.A.L. Wauters, S. Forrest, J.D. Litster, G.M.H. Meesters, B. Scarlett, Growth regime map for liquid-bound granules: further development and experimental validation, Powder Technology 117 (2001) 83–97] over the whole parameter range, for a given material and agglomeration method. Agglomeration behaviour in a high-shear mixer granulator was investigated and categorised using the evolution of granule size distribution (GSD). MCC 102 (Microcrystalline cellulose, Avicel 102) and aqueous PEG 6k (Polyethylene Glycol 6000) were employed as solid and liquid materials. Different operating conditions were applied by changing impeller speeds and L/S (liquid-to-solid) ratios (weight of liquid/weight of solid). 12 representative settings were selected and typical agglomeration behaviours were identified, forming a regime map for the system. The effect of impeller speed was found to depend on the L/S ratio, very little effect being seen at low L/S ratio (L/S = 85/150), but much more effect at higher binder ratios. In general, the effect of L/S ratio is of paramount importance in these systems and usually determines the growth behaviour.