Influence of two dispersants on the rheological behavior of kaolin and illite in concentrated calcium hydroxide dispersions

The influence of an alkylammonium surfactant and a negatively charged grafted block copolymer (CTP) onto the threshold stress value of illite and kaolinite dispersions was investigated in a strongly alkaline environment. th clay minerals, addition of hexadecyl trimethylammonium (HDMA) promotes the release of calcium ions. For kaolin KF, this release is linked at low HDMA/ kaolinite ratio with an increase of the threshold stress, and at high HDMA/kaolinite ratio with a decreasing viscosity of the dispersion. Low cationic additive concentrations coagulated the dispersions while at high additive content, repulsion between the surfactant counter ions on the particle surfaces stabilized the dispersion. trast, although addition of a comb-type copolymer with an anionic backbone (CTP) reduced viscosity of both dispersions, no calcium ion release was observed. This result indicated that CTP stabilized the dispersions by a steric mechanism.