Distribution of Solids in Stirred Suspensions

The homogeneous distribution of solid particles in stirred liquids plays an important role in industrial applications. The solids to be suspended may either be heavier or else lighter than the liquid and be of variable particle sizes and shapes. If the density of the solid material is greater than that of the liquid, it is the function of the stirrer to lift the solid particles from the bottom of the vessel and to distribute them uniformly throughout the liquid. For the design of such mixing systems it is very important to know the minimum impeller speed at which the solid particles become completely suspended. It is relatively simple to determine this critical impeller speed. Measurements of the solids distribution at different vessel heights show that attainment of the lift-off impeller speed is not in itself sufficient to ensure homogeneity of the suspension. Nor does the determination of height reached by the particles, which is a function of the impeller speed, help with the an be done on different tantalum parts to determine the amount of dissolved hydrogen.