4 - Solid-liquid separation processes

Abstract

This chapter discusses solid–liquid separation processes. Settling tanks are used to separate low solids concentration suspensions (<1% v/v). They are the simplest solid–liquid separation devices usually comprising a vessel containing a single baffle, which directs the suspension to the base from where it rises to the outlet. The type of operation ranges from simple gravity settling of suspensions containing low concentrations of solids through to slurry thickeners and finally the filtration of dense slurries. In each case, the effect of gravity can be substantially enhanced by centrifugation. These operations thus depend, for their performance, on the principles of solid–liquid flow and liquid percolation through particulate arrays. The chapter discusses the gravity settlers and thickeners, filters, and centrifuges. It inlcudes a variety of drier types that are available to remove residual moisture content for which tests are normally required prior to final equipment selection.