Effect of electrolyte concentration in process water on flocculation

Abstract

The effect of electrolyte concentration and potential determining ions on the coagulation and flocculation of illite, dolomite, and illite-dolomite mixture suspensions was investigated. Electrokinetic measurements, settling rate tests, and viscosity measurements were performed to examine the stability of these mineral suspensions and to characterize flocculants under various physico-chemical conditions. Two flocculants: A-100 anionic polyacrylamide (PAM) and polyethylene oxide (PEO) were employed. The tests revealed that polyethylene oxide does not flocculate dolomite under any tested conditions. Viscosity results corroborated that the conformation of PAM macro-molecules in water is very sensitive to electrolyte concentration; on the other hand, the conformational state of PEO macromolecules is not affected by ionic strength. The intrinsic viscosity measurements suggest that the unattainable flocculation of dolomite suspensions with PEO must result from poor adsorption of this flocculant onto dolomite particles. In both tested cases, with PAM and PEO, the relationship between coagulation and flocculation was not confirmed.