Continuous reactive crystallization of precipitated calcium carbonate (PCC) was performed in a mesoscale-oscillatory baffled reactor. Steady states were easily achieved due to a high degree of plug flow, with up to 95 % of solids suspended. The reactant concentration, the temperature, and the oscillation frequency have significant effects on the yield and particle size.

Abstract

Continuous reactive crystallization was carried out in a mesoscale oscillatory baffled reactor (meso-OBR), using calcium carbonate as a case study to demonstrate the ability of high solid loadings and to examine the fouling potential in continuous processes. Plug flow behavior was easily achieved in reactive solid-liquid phase reaction systems, as evidenced by the rapid establishment of a steady state. Effects of the operating conditions (reactant concentration, mixing conditions, and temperature) on the yield, particle size, and particle size distribution were studied. Increasing the reactant concentration and oscillation conditions reduced the particle size whereas increasing the operating temperature led to a large particle size. The meso-OBR produced uniformly shaped spherical crystals, with a 35 % reduction in average particle size and high purity compared to conventional stirred tanks. The meso-OBR could be used continuously for up to 6 h with less than 1 wt % of fouling (product loss).