schematically illustrates the mill operated with a continuous
circulation system [14]. The enclosed grinding
chamber was equipped with a cooling jacket in order to
remove any heat that developed during grinding. In this
experiment, grinding beads with a diameter of about
0.3 mm were used with a chamber fill factor of 0.85 and
a screen with mesh size of 100 mm. Firstly, 10%wt of silica
aqueous suspension (400 ml) was added to the feed tank
and then continuously pumped into the grinding chamber
at a feed rate of 40 l/h. The grinding beads were activated
by a disk rotating at a shaft speed of 3000 rpm. After
grinding for a while, the de-agglomerated particles having
a particle size less than 100 mm would pass through the
screen and be recycled into the grinding chamber. The
optimized grinding time for this continuous process was
30 min. The average particle size (d(0.5)) of the ground
silica was measured by using a laser particle size analyzer
(Mastersizer 2000; Malvern Instruments Ltd., Worcestershire,
UK). Also, the de-agglomerated silica suspension was
cast onto a cleaned glass slide and dried at room temperature
for determining its morpho