Dependence of separation properties on flocculation dynamics of kaolinite suspension

Abstract

Solid-liquid separation is widely done by polymeric flocculation. But very little fundamental information is available for sheared suspension. In this work, online measuring of the particle number concentration, flee size and flee size distribution has been done in stirred suspension to understand the effects of addition of flocculant in stages, agitation speed and time, pH and solids loading in a kaolinite suspension on formation, growth, breakage and conformation of flocs and finally on separation properties, namely, turbidity of the suspernatant, capillary suction time (CST) and specific resistance to filtration (SRF). The exact amount of flocculant required for optimum results can be determined by stage addition of flocculant. The best separation properties are obtained from the flocs which can withstand shear for a long time. Higher agitation speed reduces the mean flee size and narrows the size distribution.