FORMATION OF PELLET FLOGS FROM KAOLINE SUSPENSION AND THEIR PROPERTIES

Abstract

Kaoline suspensions of 7.5 kg/m³ are flocculated by consecutive dosage of inorganic salt and nonionic polymer flocculant and the properties of floes are investigated. It is found that four different types of floes are possibly formed: microflocs, small and large pellet-floes, and bulky floes; and that the formation of pellet-floes depends on the polymer concentration, the stirring intensity, the stirring time and the way of stirring. Pellet-floes are found to have the following features: (a) the size is large and the shape is nearly spherical; (b) the effective density is nearly constant independently of the floe size, and so the sedimentation velocity is extremely large compared with that of microflocs; (c) the filtration resistance of the filter cake is very small; (d) the drying time of the filter cake is as short as that of microflocs; and (e) the total dehydration time of small pellet-floes is the shortest.