Agglomeration and de-agglomeration of cohesive particles in a vertically vibrated bed

Cohesive forces play an important role for particles with sizes below 100 microns. The focus of the current work is investigation of deagglomeration under vibration using simulations based on discrete element method. Simulations are performed using the opensource software LAMMPS. Analyses are carried out at two different levels. First, a system of multiple agglomerates, where agglomeration and deagglomeration occur simultaneously, in a vibrated bed, were studied. Second, the deagglomeration of a single agglomerate under vibration is investigated to determine the rate of the attrition and/or breakage of the cohesive cluster. Particles with a wide range of sizes from 50 nm to 100 microns are used. Simulations are performed with different contact models. A set of simulations were carried out using a combination of a linear spring and van der Waals force model. Simulations were also performed in which Hertz-JKR model was used to determine the contact force between the particles. This is to ensure the size indepence of the results. In multiple agglomerate systems, three different regimes exist depending on the ratio of the maximum energy of the vibrating base to that of cohesive energy. Deagglomeration of a single cluster under vibration is observed to obey first-order kinetics. The deagglomeration rate constant shows an Arrhenius-type behaviour. Results obtained with linear-spring-van-der-Waals are consistent with those of the Hertz-JKR model.