Abstract
Mono-core coating process using a draft-tube spouted-bed (DSB) with a converging nozzle and medium particles is proposed for fine and adhesive particles. In order to avoid the formation of agglomerates which tends to occur in the conventional fluidized bed coater, many attempts have been made in the past to establish improved fluidized bed coaters such as a spouted bed with a draft tube (DSB) and circulating fluidized bed coater. However, it has been found very difficult to perform coating on fine particles without forming agglomerates by these methods. In this study, the DSB with a converging nozzle and medium particles, in which the exfoliation effect and the disintegration force can be expected, is used for coating fine and adhesive particles with finer powder.
As a result, it was found that the mono-core coating of fine particles of an average diameter of about 26 μm could be achieved by using DSB with medium particles. However, it was shown difficult to control the amount of coating powder adhered to the seed particles was difficult because the exfoliation of coating powder occurred by the collision between medium particles and seed particles. Also, it was found that the coating efficiency of seed particles decreased with the increase of inlet gas velocity.
