| Abstract |
The synthetic flocculants are polymers based on acrylamide and its copolymers. These are composed of nonionic, cationic and anionic charged formulas which are primarily produced for filtration processes and waste water clarification. The effect on sedimentation rate and flocculation of silica with the presence of inorganic electrolytes and in combination with the organic polymer flocculants were measured using a turbidimeter The cationic polymers were found to coagulate silica rapidly in geothermal liquid at concentrations of 5-20 ppm. The silica aggregates were formed by a rapid irreversible reaction which produced smaller particle aggregates that did not settle. The increase in turbidity correlates to the increasing charge of the cationic polymers. The anionic polymers did not increase aggregation when applied alone, but they did increase the settling rate of previously aggregated silica. The aggregation is initiated by adding polyaluminum chloride and flocculantion is enhanced by adding anionic polymers. Flocculation is also enhanced by anionic polymers when combined with magnesium chloride. The nonionic polymer tends to stabilize the aggregated silica particles formed by polyaluminum chloride but also enhances the flocculantion when combined with magnesium chloride. The aggregation of silica is increased by addition of polyaluminum chloride, FeC13 and Ca(0H): at concentrations as low as j ppin. Rapid flocculantion (less than 30 minutes settling of silica occurred by addition of ,700 ppm polyaluminum chloride or 50 ppm lime (ppm as Ca ). MgCIi2 increased the flocculation at 300 ppm MG. There was no enhancement of flocculantion using CaCl2 alone for the range of concentrations (20-300 ppm) tested. |