The mixing processes of slender particles in a rotary dryer fitted with lifters were simulated in three dimensions. Particle motion was modeled by the Discrete Element Method (DEM) and a three dimensional collision model for slender particles was developed. Contact force, friction force and gravitational force acting on an individual slender particle were considered when establishing mathematics models. The influences of rotational velocity on the mixing of slender particles were discussed and compared with those of spherical particles under identical operating conditions. It was found that the mixing characteristics of slender particles and spherical particles all followed a constant rate until a completely mixed state was encountered. But there were still certain differences between these two kinds of particles. The influences of the lifters with different shapes were further discussed for slender particles. Selected stimulation results were obtained and would provide consults for the further study of slender particles. (C) 2009 Elsevier B.V. All rights reserved..