2016 Volume 53 Issue 11 Pages 710-716
Direct granulation of agrochemical suspension was carried out to prepare water dispersible granule （WDG） by using a fluidized bed. The effects of liquid flow rate and spray air pressure on granule growth, pore size distribution and disintegration time in water were investigated experimentally. It was found that granule growth mechanism of primary particles can be explained by layering and agglomeration granulation. Cross-sectional view of SEM images revealed that the granules have dense inner structure regardless of the operating conditions. Mass median diameter increased with an increase in liquid flow rate and a decrease in spray air pressure. The disintegration time in water decreased with a decrease in liquid flow rate and an increase in spray air pressure, and it was well correlated with the volume in pore size of around 10～30μm measured by a mercury intrusion method. It was indicated that the disintegration time which is one of the most important properties in WDG could be controlled by parameter adjustment of the direct granulation method using fluidized bed.
