Improvement of the material motion in a rotary processor.

The purpose of this paper is to reject or to confirm the hypothesis that the influence of the water addition rate on the size and size distribution of pellets is caused by insufficient spreading of the added water at higher water addition rates. To overcome insufficient spreading of the added water, the agitation in the rotary processor is intensified by improving the spiral, rope-like movement by means of two baffles and a permanent PTFE coating, and by installing a chopper. Improvement of the spiral, rope-like movement moderates the influence of the water addition rate on the pellet size. The chopper has no significant influence on pellet size, pellet size distribution, or percentage of agglomerates for the pellets, which are investigated in this study. Furthermore, the implementation of the technical modifications does not influence the dissolution characteristics of the pellets directly. It is therefore concluded that the water added is well spread over the mass by ensuring an optimal spiral, rope-like movement, so that incorporation of a chopper is superfluous. The remaining influence of the water addition rate on the pellet size can most probably be explained by differences in processing time, resulting in different volumes of air capable of extracting water from the powder mass.