Rheological Behavior of an Algerian Natural Kaolin: Effect of Dispersant

Abstract

This work presents the study of the rheology ical behavior of Algerian kaolin (DD1) suspensions considering two types of electro-steric dispersants (Hypermer KD1 and Darvan 7) and the evaluation of their effectiveness at neutral pH. The results showed that Darvan 7 exhibits electro-steric behavior at neutral pH, whereas KD1 exhibits purely steric behavior. The addition of a dispersant strongly influenced the rheological behavior of kaolin suspensions. The DD1 suspensions without dispersant exhibited fluidifying plastic behavior (Casson model). The shear stresses decreased significantly with the addition of dispersant, while the significant decrease in viscosity indicated that the dispersant reduced the strength of the particle networks that make up the slurry. The suspensions with 1 wt.% dispersant were consistent with the Bingham model, with a very low yield point. The viscosity of the dispersion reached a minimum when the concentration of the dispersant was 1 wt.%. This value was lower with Darvan 7. The addition of aluminum slag as a source of alumina to KD1 increased its efficiency and lowered the viscosity of the kaolin suspensions.

Keywords

• kaolin suspension
• rheology
• viscosity
• steric stabilization
• zeta potential
• electro-steric