Adhesion of an Aqueous Polymeric Suspension to Inert Particles in a Spouted Bed

Abstract

Among the several unit operations that seek the modification of superficial characteristics of solid particles, the spouted bed appears as efficient technology for coating of coarse particles (d _p  >1 mm). This work aimed at investigating the fluid-dynamics of the conventional spouted bed during a coating process, using several inert particles such as polystyrene, polypropylene, polyethylene of low density, ABS®, placebo tablet and glass beads, and analyze the influence of the physical properties of the particles and of the polymeric coating suspension on the fluid dynamics. The suspension was characterized by the surface tension, density, rheology, and contact angle between the suspension and the solid surface. It was verified that the particles having a high contact angle with the suspension (polystyrene, polypropylene, and low-density polyethylene) were not coated, and drying of the suspension was obtained in these cases. For the other particles (ABS, tablet, and glass beads), coating efficiencies in the range of 76–90% were obtained. The shape, angle of repose, and density of particles affected the fluid-dynamic during the coating, and also the inter-particle friction and the particle circulation velocity in the bed.

Keywords:

• Contact angle
• Spouted bed fluid dynamic

Acknowledgments

The authors acknowledge the financial support received from Foundation for Research Support of São Paulo State, FAPESP, and CNPq for this research.