Single drop behaviour in a high shear granulator

Abstract

The wet granulation process starts when a liquid drop makes contact with the powder bed. In a powder bed, drops are subjected to centripetal and gravitational forces. These forces may affect the size and shape of the drop as it is incorporated into the bed. The majority of experiments studying droplet behaviour have been performed on static bed surfaces. This paper seeks to demonstrate droplet behaviour during the initial contact stage with a dynamic powder bed representative of that occurring during high shear granulation. Particle image velocimetry (PIV) is used to determine droplet and powder bed surface velocities. Due to inclination of powder bed part of drop de-accelerate slowly moved downward while other parts remain attached to powder bed this result in their deformation and breakage. Amount of deformation of drop and span of area where it occurred was increased as drop was added farther from the outer edge of the mixer. This paper shows that the binder drop may deform or break in high shear granulator depending on its initial impact position. This will affect size distribution and other properties of nuclei.