Settling Behavior of the Suspended Particles in the Hindered Settling Range (4th Report)

This is the fourth of a series of papers dealing with the solid-liquid sedimentation phenomena in thehindered settling range.In the previous papers, experiments were performed to confirm the effect of the suspended solid density ofup to 15 vol.% on the settling rate with using the samples of the different nature. Authors analyzed these results and proposed the experimental equations (1) to (2). Simple correlations were observed among the coefficients of each equation which could be represented in terms of the apparent particle size, Xm, of the samples under hindered settling.The present report is associated with the, examination of the applicability of these equations to higher density regions on six samples of which two were also tested with organic and inorganic flocculents.Experimental results were interpreted in terms of the rheological property of the slurries tested.It was found that these equations are valid only within the Newtonian fluid region referred to simply as the ‘hindered settling’ in the authors' previous papers. In higher density regions where the flow characteristics are pseudoplastic or dilatant, those experimental equations were not followed precisely.However, even in this non Newtonian fluid region, the mean settling rate was approximately evaluated by the modified experimental equation, (2), using the correlation between Xm and the solid density. The experimental results were also compared with the equations described in the literature.