AN APPARATUS AND METHOD FOR COATING OF SOLID PARTICLES

A method for the coating of discrete solid particles and a diagram of the apparatus used is presented. In this process, solid particles are educted from a fluidized bed by a turbulent gas jet, separated into discrete units, and transported upward through a converging cone into a coating application zone. In this zone, the solid particles are contacted by discrete liquid droplets comprising the coating material. These liquid droplets are entrained in a downward moving airstream which has a greater velocity than the upward moving solid particles. The velocity differential removes the wetted solid particles from the coating zone and returns them to the fluid bed. The coating liquid is spread over the surface of the solid particles in this bed prior to their reeduction into the turbulent gas jet. The cycle is repeated until coatings of the desired kind and thickness are obtained. Copyright © 1968 Wiley‐Liss, Inc., A Wiley Company