Development of Empirical Correlations for Differential Settling of Bidisperse Suspensions Based on Monodisperse Equations Covering Wide Range in Solid-Liquid Concentration

P. Krishnamoorthy¹* and T. Murugesan²

¹Department of Chemistry. St. Joseph’s College of Engineering, Chennai - 600 119 (India) ²Department of Chemical Engineering, A.C. College of Technology, Anna University. Chennai - 600 025 (India)

The present work involves the prediction of empirical correlations for differential settling of bidisperse suspensions based on the existing monodisperse correlations available in the literature. Experimental investigations on the settling rate of bidisperse suspensions in liquids using particles of equal density are being reported with a view to measure experimentally the lower and upper interface velocities in bidisperse suspensions of solids in liquids in the Stokes region. Wide rage in the properties of the liquids and solids, and more specifically in solids concentration (Glass ballotini and Sand) covering concentrated and dilute suspensions are covered. The solids concentration ranges from 0.38 to 0.05(Voidage from 0.62 to 0.95). Empirical models are proposed relating the interface velocities to the solids concentration (or voidage), based on the equations given for monodisperse suspensions. Unit operations such as classification, thickening, clarification, de-watering, fluidization, pneumatic transport, solvent extraction, flotation, drying, cooling and reactors involve sedimentation of mixtures of various degrees.

Settling, Fall Velocity; Differential Settling; Bidisperse Suspensions; Interface velocity