The present work analyzed aspects of the fluid dynamics of the conventional concurrent dryer equipped with lifting flights and their influence on the performance of a rotary dryer. The drying of granulated fertilizers (GTSP) in a conventional concurrent rotary dryer was experimentally investigated and compared with a modified configuration known as the roto-aerated dryer. The main feature of this new dryer is the presence of an aerated system consisting of a central pipe (encased in the drum) from which a series of mini-pipes lead hot air directly to the particle bed, flowing at the bottom (without flights). The results obtained confirm the superior performance of the roto-aerated dryer due to its more effective gas-particle contact.