Studies on flocculation of Egyptian kaolin suspensions by anionic polyacrylamide in the presence of surfactants

This papers reports the results of studies on flocculation of kaolin suspension by anionic polyacrylamide (PAM-A) flocculants in the presence of surfactant. They were namely anionic Sodium Dodecyl Sulphate (SDS), cationic Cetyl Trimethyl Ammonium Bromide (CTAB) and a non-ionic surfactant of polyoxyethylenic ether with trade name Triton (TX 100). The adsorption of PAM-A for fresh kaolin as well as surfactant pretreatment kaolin corresponding to about 50% coverage on the surface. Pretreatment of kaolin with all three surfactants form bigger flocs with PAM-A. The highest settling rate is obtained by flocculation the SDS-pretreatment kaolin. The influence of simultaneous addition of PAM-A and surfactants from their mixtures on flocculation is dependent on the nature of mutual interaction of PAM-A and surfactant. Simultaneous addition of PAM-A with either SDS or TX 100 increases settling rate, whereas it decreases when added from its mixture with CTAB. On the other hand, the optimum dose of PAM-A and 0.2 g/ kg SDS-pretreatment preconcentrate El-Tih Egyptian kaolin is applied. The flocculation product a kaolin concentrate of minimum TiO2 content (0.27%) and the degree of whiteness (93.5) is obtained from TiO2 content (1.52%) and the degree of whiteness (63) of the original.