Effect of Particle Wettability on Particle-Particle Adhesion of Colliding Particles through Droplet

In an actual wet granulation processes, a liquid bridge between particles is not static but dynamic due to continuous particle motion. Therefore, to fully understand the micro-level particle agglomeration phenomena, elucidation of the particle-particle adhesion by the dynamic liquid bridge has been an important issue.

Numerous studies of the liquid bridge have been conducted. However, the particle-particle adhesion by the dynamic liquid bridge cannot be explained by these conventional theories and analytical models, because deformation of the liquid bridge is not taken into account. Thus, we have developed a direct numerical simulation model for the particle-particle adhesion by the dynamic liquid bridge. By using this simulation model, effects of many critical parameters such as particle colliding velocity and physical properties of particle and liquid can be directly analyzed.

We here conducted a numerical simulation of the particle-particle adhesion by a dynamic liquid bridge. The particle-particle adhesion of two colliding particles through a droplet on a particle surface was simulated. In particular, effect of particle wettability on a critical velocity for the particle adhesion (i.e., adhesiveness of the two colliding particles) was investigated. It was found that the critical velocity for the particle adhesion non-linearly changed with the particle wettability. The critical velocity exhibited a local maximum with an increase in the contact angle, while the static liquid bridge force monotonically decreases with an increase in the contact angle. We revealed that a combined effect of the liquid bridge deformation and instantaneous liquid bridge force results in the non-linear dependence on the particle wettability.