An Experimental Investigation of Dry Granulation

Abstract

Dry granulation behaviour of powders is dominated by a number of factors, such as process conditions (roll speed, roll gap, feeding mechanisms and feeding speed) and powder properties (particle size and shape). In this study, the effects of particle size on the dry granulation were investigated experimentally. Microcrystalline Cellulose (MCC) (Avicel PH-101 and Avicel PH-102) were compacted using an instrumented roll compactor developed at the University of Birmingham. It was found that the powder particle size has a significant effect on the powder flow behaviour during roll compaction. The powder of small particle size tends to form agglomerates on the surface of the powder bed. Non-uniform powder flow into the compact zone causes a variation in bulk density across the ribbon width. It is demonstrated that the ribbon solid fraction and granular size depend upon the powder particle size. Attrition test was also carried out to investigate the effect of ribbon properties (i.e. solid fraction and tensile strength) on the ribbon mass loss and breakage. It was interesting to note that the ribbon mass loss was dominated by different attrition mechanisms (i.e. erosion and ribbon fragmentation) depending on the duration and severity of attrition.