location: >Calculations >Sedimentation
| This page provides
details of sedimentation processes: the basic types being: free settling and
clarification, incompressible hindered settling (as described mathematically by
Kynch) and compressible sedimentation or consolidation. We have already
implemented pages for interactively calculating free settling velocity, and here we extend
this to provide routines for equipment specification. Details of techniques to
enhance sedimentation by flocculation and coagulation will also be covered.
Currently, the best example of the different types of sedimentation equipment,
and how they might be used, can be found at Josh's web site:
Separation.com. Josh provides a very useful set of notes and pictures, but
doesn't provide the interactive facilities given here.
| Please do take a look at
Josh's site but use this site for your interactive equipment selection and
|Continuous sedimentation - thickening
illustrative design procedure that takes inputs on thickener feed rate, etc. and
provides the required area in order to achieve the desired underflow
concentration. The procedure is based on the classic approach of
Coe and Clevenger in which the area is calculated for each
concentration that exists in the thickener between the feed
and the underflow value. The actual area built should be equal to,
or greater, than the largest required area in the table.
Also, included in the output table are values of predicted
settling velocity and batch flux.
Settling velocity is predicted by equating the bed weight to liquid
drag, as given by the Kozeny permeability expression. These are
hindered settling velocities that are, therefore, much slower than the
free settling velocities given here.