Generalized Stokes number for modeling settling of non-Newtonian slurries in dynamic separators

Abstract A ‘generalized’ Stokes number to evaluate free-fall velocity of particles in non-Newtonian suspensions is proposed. It was derived for power-law slurries of concentrations up to 25% in volume. Shear thickening suspensions of dolomitic limestone were tested in three geometrically similar hydrocyclones of 22, 44 and 88 mm body diameter. The separation efficiency of these units was related to the cut size as obtained from the proposed Stokes number and compared with the traditional approach of considering the suspension Newtonian. The results demonstrated that evaluation efficiency is more reliable using this form of the Stokes number and that errors may be minimized, even at slurry concentrations as low as 5% in volume. The term ‘generalized’ is used to imply that, for Newtonian suspensions, the number would reduce to the common form normally reported in the literature.