Study of silica particle aggregation in a batch agitated vessel

The aggregation kinetics of precipitated silica particles is studied in a l aboratory batch reactor. A method using destabilisation of a silica sol is developed to observe the aggregation process in absence of any other precip itation phenomena. The evolution of the moments of the particle size distri bution (PSD) against time shows that the silica aggregation proceeds in two stages - a perikinetic aggregation stage, for particles smaller than 250 n m, whose kinetic rate depends on physico-chemical parameters, and a rapid o rthokinetic aggregation stage, for larger particles. Once they have reached their maximal size, particles undergo breakage, whose rate depends on hydr odynamic conditions. Expressions for the evolution of the first moments (up to sixth order) against operating conditions are derived. (C) 2001 Elsevie r Science B.V. All rights reserved.