A preliminary numerical investigation of agglomeration in a rotary drum

In this paper, the discrete element method (DEM) is employed to analyse the wet granulation process. It is essentially a computer simulation of various types of interactions of particles in a rotating drum that eventually results in tracking of trajectories of each particle and particle agglomerates. Non-linear spring-dashpot type contact models are used to monitor particle-particle and particle-wall interactions. The contact between the particles in the presence of a binder is modelled by the well-known JKR theory. To establish the potential of this numerical approach, a 10-cm rotating drum is simulated with a polydispersed system of particles of top size 1 mm. A scraper is suitably located within the drum to restrict the motion of the adhered particles along the mill shell. A spray zone is located within the drum such that the particles receive the binder dosage only within this spray zone. A drying time is also specified beyond which the particles no longer adhere together. Implementation of these ideas within the computer program makes the simulation more realistic, which in turn allows prediction of the steady-state size distribution of the agglomerates. (C) 2002 Elsevier Science Ltd. All rights reserved.