Agglomeration kinetics of submicron barium sulfate precipitates

Abstract: Unwanted agglomeration, especially in highly concentrated submicron and nano- particle suspensions, can rapidly change the physical product properties of produced particles. Knowledge of the agglomeration kinetics and mechanisms is crucial to achieve control over this secondary sub-process of particle formation. To obtain this kinetics a new measurement method is presented to monitor the shear induced agglomeration behavior of submicron barium sulfate particles while passing a narrow pipe. The residence time, i.e. agglomeration time was varied with the pipe length at constant suspension flow rate. Before measurement, the particle suspension was stabilized by rapid mixing with a dispersing agent. Based on measured agglomerate size distribution, the agglomeration behavior is discussed in terms of non-turbulent flow in a narrow pipe. Barium sulfate agglomeration in a simple shear flow could be monitored on submicron scale. The effect of steric stabilization to reduce or prevent agglomeration was shown and quantified. The controlling mechanism for agglomeration in a pipe is identified based on the hydrodynamic characteristics. The adhesion probability was found to decrease with agglomerate size. [Copyright &y& Elsevier]