Preparation of pellets of different shape and their characterization

Pellets of different shapes were produced by modifying the processing parameters of a standardized pellet formulation. The target size of these pellets was 1-1.4 mm. Initially the shape of the pellets was assessed by visual observation. In total, eight batches of pellets were produced of which four were considered to be round, whereas the other four deviated from the spherical shape by various degrees. The different pellet fractions were then characterized for their size, shape, surface, and density properties employing a series of established techniques in order to identify the most appropriate method of characterization and the interrelationships between these properties. The results showed that attempting a task of preparing pellets of graded differences in shape from the same powder blend can result in changes of other important pellet properties such as surface roughness, surface area, and pellet dimensions. Some of these changes could be anticipated by considering the process variables involved, whereas others changed in a manner for which there is no immediate explanation.