2018 Volume 55 Issue 6 Pages 316-323
Fluidized bed granulation by spraying purified water as a binder liquid was carried out to prepare granule consisting mainly of insoluble inorganic compounds. The effect of changes in moisture content on granule growth was investigated experimentally by using an online particle imaging processor. It was found that granule growth mechanism in fluidized bed granulation can be explained by relationship between moisture content and plastic limit of the powder. Increase of mass median diameter after forming nuclear particle was observed when the moisture content exceeded the threshold of moisture content and its value was almost the same as the plastic limit. It was also indicated that the free water on the particle surface caused secondary granulation and pores in the particle caused breakage of the secondary granule in drying stage. The mass median diameter could be controlled by determining the water spraying endpoint.
