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 l ends to a less predictable process and a decrease in the usable portion of the the total product yield obtained from each production run. The use of v ariable speeds of the rotating frictional base plate during the spheronizat ion run was investigated for achieving optimal spheroid production. When th e base plate speed was increased during liquid addition, the greater centri fugal forces generated improved liquid distribution and the mixing of the m oist powder mass, resulting in a decrease in the amount of oversize particl es formed. When the base plate was maintained at a high speed throughout, t he run the amount of oversize particles and mean spheroid size increased, a nd a greater "between batch" mean spheroid size variability was also observ ed The findings showed that, when higher speeds were used, the residence ti me must be adjusted accordingly to avoid excessive coalescence and growth w hile maintaining even liquid distribution. A ''low-high-low'' speed variati on during rotary processing may be used to produce spheroids with a narrow size distribution and with a minimal amount of oversize particles in the to tal product yield.