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Compression zone effect in batch sedimentation
Author(s) -
Font R.
Publication year - 1988
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690340207
Subject(s) - settling , sedimentation , arithmetic underflow , sediment , soil science , mineralogy , mechanics , compression (physics) , geology , chemistry , geotechnical engineering , materials science , environmental science , environmental engineering , physics , composite material , geomorphology , computer science , programming language
Theories of batch sedimentation, taking into account the compression zone effect, are reinterpreted and modified. According to the discussion presented and the experimental results shown, characteristics—which are the loci of points representative of layers with the same settling rate and the same solids concentration in the settling zone—rise tangentially to the sediment curve on a height vs. time plot. Mathematical expressions that relate the solids concentration to the variations of the pulp‐supernatant interface height and of the sediment height are presented. In addition, the model presented is proposed for use when it is not possible to measure the sediment height. A procedure for calculating the concentration at the top of the sediment is also indicated. Calcium carbonate suspensions in water were selected for testing the equations deduced. The relation between the continuous thickener unit area and the underflow solids concentration was obtained from the batch tests, and is compared with that calculated by the graphic methods of Talmadge and Fitch, and Fitch.