Solids settling velocity and distribution in slurry reactors with dilute pseudoplastic suspensions

The solids distribution was investigated in a tank stirred with multiple Rushton turbines. The analysis of the behavior of suspensions made of solid particles and non-Newtonian liquids allowed us to better single out the role of the most significant parameters that define the solids profiles: particle settling velocity is confirmed to be a key parameter for this process. It is shown that the same concept of terminal velocity in these systems is to be considered with care. The settling velocity in the stirred liquid is usually intermediate between the terminal settling velocity in the still liquid and the terminal settling velocity calculated with an effective liquid viscosity based on Metzner and Otto's concept. A correlation between the first and last settling velocities with the ratio of Kolmogoroff length scale and particle diameter is in very good agreement with that determined previously for Newtonian liquids.