Particle concentration and mixing characteristics of moderate-to-dense solid-liquid suspensions

Mixing time, power consumption, and solids concentration were measured in solid-liquid flow in a T = 290 min vessel stirred by a Rushton turbine (D = T/3). The influence of particle size, density, and concentration, as well as impeller off-bottom clearance, on the mixing characteristics of two-phase flow was studied in the Reynolds number range 10 000 < Re < 200 000 for concentrations up to 15.5 vol %. The mixing time measurements revealed the presence of a peak in the number of revolutions necessary to achieve full mixedness, in comparison to the single-phase results. Power consumption was determined with a strain gauge technique, and the power number variation with impeller speed showed a similar trend for all slurries tested. The local solids concentration was measured at different heights and radii in the vessel using a conductivity probe to study the quality of solids distribution and the amount of solids suspended with speed.