(601e) Preparation of Highly Concentrated Solid-Liquid Dispersions Using Smx Static Mixers

This paper aims at demonstrating the efficiency of the SMX static mixing units in the preparation of solid-liquid dispersions, especially when concentrations above 40 wt% have to be reached. SMX static mixers of two different sizes, and containing from 6 to 24 elements were used in circulation loops powered by positive displacement pumps. Both pressure drop and an in-line size measurement device were used as process monitoring information in order to determine the end of the size reduction process and the total amount of dispersing energy required. Delaminated clays and precipitated calcium carbonates were the solids considered. Results clearly demonstrate that the SMX static mixer is able to effectively generate size reduction, almost down to the primary particle size, without requiring important energy consuming devices. It is also possible to effectively disperse solids within a single passage through a static mixer series when appropriate processing conditions are met. Moreover, static mixers intrinsically deal with the difficult rheological behavior of concentrated suspensions that very often lead to cavern formation when prepared with rotating impellers such as saw tooth impellers. Finally, it is shown that simple process configurations and monitoring, when coupled to efficient pumping capacity, can effectively be used to prepare solid-liquid dispersions at concentrations above 60% and that such systems can easily be implemented in new installations hence replacing costly and cumbersome equipments.