Wet agglomeration processes have predominantly been investigated by ch
anging operation variables of process-scale experiments. So far, most
fundamental work concentrated on the strength of the liquid bonds in t
he agglomerate and its relation to the process. Previous studies on th
e relationship between droplet size and agglomerate size in fluid bed
agglomeration indicated that, besides agglomerate strength, liquid dis
tribution determines the agglomerate properties to a large extent. Thi
s paper focuses on the mechanism of growth of a single agglomerate ori
ginating from one droplet of binder liquid. A model is introduced whic
h describes agglomerate growth as a function of time. We discern two s
tages of growth of an agglomerate. Initially, fast growth takes I,lace
by wetting of the powder particles by a droplet, which result in the
formation of an initial agglomerate. This stage of fast growth is foll
owed by a second stage of slower growth, which results from drainage o
f binder liquid from the initial agglomerate to the outer layers of th
e growing agglomerate. This model predicts agglomerate growth and the
final agglomerate size by taking into account the particle sie distrib
ution, the viscosity, the surface tension, the contact angle, the poro
sity, the wetting saturation and the residual saturation. Experimental
results were in good agreement with the model. (C) 1998 Elsevier Scie
nce S.A. All rights reserved.