Mathematical Modelling of Granulation Processes

This thesis studies wet granulation on three different levels. First, micro-level investigations of liquid bridges between two and three particles are performed. For the two-particle case, the fluid profile of static (stationary) and dynamic (moving) liquid bridges are investigated. Static liquid bridges between three equally sized primary particles are then studied; the symmetry of the problem is used to obtain a numerical solution to the Young-Laplace equation. Secondly, a model to estimate the stickiness (fractional wet surface area) of agglomerates is proposed. The model includes parameters to control the inter-particle separation distance and the fluid saturation state. Computational geometry is used to obtain results which relate the number of particles and the volume of binder fluid to the stickiness of the agglomerates. Finally, a population balance model for wet granulation is developed by extending an earlier model to incorporate the effects of binder fluid. The model is solved numerically for a range of coalescence kernels and results are presented which show the effect of binder volume and the drying rate.