Characteristics of flocculation of mineral suspensions by polymers

Abstract

The mechanism of flocculation by polymers has been examined by a study of fluorite suspensions. The “bridging” theory accounts qualitatively for the data—e.g., the influence of mol. wt., the much stronger mutual adhesion of particles (and hence the more open structure of flocs) than those resulting from electrolytic coagulation, etc. However, the quantitative theory of refiltration curves developed by Smellie and La Mer is shown to be invalid, because it is based on erroneous assumptions as to the origin of the permeability maximum. The mechanism of adsorption of polymers by ionic crystals such as calcium fluoride has been considered, and the possibility of dipole interaction of non-ionic groups with the electrostatic field of the crystal lattice is suggested.