The influence of ammonia content and of the retention time on the crys
tal size distribution of magnesium hydroxide prepared by the precipita
tion from Mg(NO3)(2) solutions in a flow reactor was investigated. The
temperature of the reacting mixture was 80 degrees C. It was found th
at the higher is the content of ammonia and/or its surplus with respec
t to the stoichiometric demand, the larger are the Mg(OH)(2) crystals.
The longer is the retention time, the lower is the fraction of the pa
rticles smaller than 24 mu m in the product. When the retention time o
f Mg(OH)(2) in the reactor is shorter than 3 min, irregular agglomerat
es of Mg(OH)(2) with sharp edges are formed while at the retention tim
e longer than 5 min the aggregates have a round shape.