For the more clear understanding of sedimentation phenomena, a study on sedimentatios in suspensions of various divided solid particles is presented.
1) The concentration gradient along the depth of suspension, containing the solid particles the size distribution of which is represented by, can be expressed by
If the particle size distribution and the rate of sedimentation are given, we can solve this equation by a graphical method.
2) The general equation of the rate of sedimentation of such solid particles is given by
From the data obtained by our experiments using suspensions of various sized silica particles the following empirical formula is obtained;
The rate of sedimentation of the suspension of uniform particles is obtained by putting w=w0 in the previous equation; v=vsψ(w0)=cx2(1-w0/ρs)210-2.36·w0/ρs In this case the rate of sedimentation is the same as that of the subsidence of the surface of suspension.
3) The concentration gradient along the depth of dilute suspensions of silica, to which the Stokes law would be applied, is given by the following equation;
This relation shows that the rate of subsidence of the surface of suspension may be governed by the Stokes velocity of their minimum particles.
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