Powder coating efficiency of small particles and their agglomeration in circulating fluidized bed

The coating efficiency of fluidizing small particles and their agglomeratio n were investigated to evaluate the possibility of powder coating by the us e of a circulating fluidized bed. Glass beads, whose mean diameter was 43 m u m, and silica powder of 1 mu m were used as a core and a coating material . Polyvinyl alcohol was used as a binder and its solution was supplied toge ther with silica powder from a spray nozzle equipped in the circulating flu idized bed. Glass beads of 43 mu m, which had been impossible to coat in a conventional fluidized bed coater, were successfully coated with silica pow der in a circulating fluidized bed, and agglomeration among core particles was prevented. From this result, it was confirmed that a circulating fluidi zed bed performs excellently as a coater, especially for fine core particle s, so a circulating fluidized bed coater has bright prospects for particle coating.