AGITATION POWER FOR SOLID-LIQUID SUSPENSIONS CONTAINING LARGE PARTICLES

The agitation power required by Liquid-solid suspensions of large PVC discs (4.3 mm) and sand granules (1.29 mm) in water was measured for v arious solids concentration, up to 16% by volume, using 5 different im pellers. In all cases the dispersed power increased with increasing so lids content, more than expected based on the suspension density. The solid phase actually dissipates energy due to particle-liquid friction and in the collisions of the particles. The amount of energy disperse d according to these mechanisms is generally low, but becomes evident with the large particles as the solid concentration increases above 44 %.