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Transport characteristics of suspensions VII. Relation of hindered‐settling floc characteristics to rheological parameters
Author(s) -
Thomas David G.
Publication year - 1963
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.690090308
Subject(s) - settling , rheology , flocculation , suspension (topology) , colloid , chemistry , thermodynamics , laminar flow , materials science , chemical engineering , composite material , mathematics , organic chemistry , physics , homotopy , pure mathematics , engineering
Both the rheological and the hindered‐settling characteristics of small particle size suspensions (0.1 to 50 μ) are primarily determined by the degree of flocculation and the concentration of the suspension. Previous studies have shown that when the laminar shear diagrams are fitted by the Bingham plastic model, the parameters τ y /ϕ 3 and ϕ −1 In η/μ are constants which are proportional to the degree of flocculation The present study showed that these rheological parameters were proportional to the value of α determined from the hindered‐settling measurements (α is defined as the ratio of the volume of fluid immobilized by the floc structure to the volume of solids in the floc structure). The materials studied included suspensions of thorium oxide in water and methanol and of titania, kaolin, alumina, and graphite in water. The particle size range was from 0.40 to 17.0 μ Values of the attractive force between particles calculated from the rheological and hindered‐settling data were in good agreement with each other and with the theoretical values calculated from the Derjaguin‐Verwey‐Overbeek theory of colloid stability. The good agreement among the different values suggests that the present approach may be generally applicable to a variety of different systems.