The flocculation efficiency of some cationic amphiphilic dextran derivatives has been investigated in zirconium silicate suspensions with respect to settling time, polycation dose, its chemical structure and molar mass. The presence of pendent cationic groups and the length of the alkyl substituent at the nitrogen of pendent groups were crucial for the efficacy of flocculation process, in terms of the optimum polymer dose and the flocculation window width. Within the range of 10-400 kDa, no significant effect was observed on the separation efficacy. The negative values of the zeta potential at the optimum polymer dose point to contributions from charge patch mechanism and hydrophobic associations for the flocculation process. This kind of polymers has been also proved to be efficient flocculants for kaolin and 25/75 zirconium silicate/kaolin mixture suspensions. Furthermore, the presence of kaolin in the above mentioned mixture led to acceleration of the particles flocculation. (C) 2014 Elsevier B.V. All rights reserved.