Role of base plate rotational speed in controlling spheroid size distribution and minimizing oversize particle formation during spheroid production by rotary processing.

The occurrence of material adhesion and formation of oversize particles in the product yield during one-pot spheroid production by rotary processing leads to a less predictable process and a decrease in the usable portion of the total product yield obtained from each production run. The use of variable speeds of the rotating frictional base plate during the spheronization run was investigated for achieving optimal spheroid production. When the base plate speed was increased during liquid addition, the greater centrifugal forces generated improved liquid distribution and the mixing of the moist powder mass, resulting in a decrease in the amount of oversize particles formed. When the base plate was maintained at a high speed throughout the run, the amount of oversize particles and mean spheroid size increased, and a greater "between batch" mean spheroid size variability was also observed. The findings showed that, when higher speeds were used, the residence time must be adjusted accordingly to avoid excessive coalescence and growth while maintaining even liquid distribution. A "low-high-low" speed variation during rotary processing may be used to produce spheroids with a narrow size distribution and with a minimal amount of oversize particles in the total product yield.