Removal of Silica from Geothermal Brine by Seeding Method Using Silica Gel

Abstract

In order to apply a seeding method to the removal of silica from geothermal brines, the effects of temperature, initial seed concentration and initial silica concentration on the silica removal were experimentally examined. When silica gel seeds are added to a supersaturated silica solution, amorphous silica is precipitated on the pore surface of the seeds and the silica concentration in the solution decreases. The silica removal ratio, which means the ratio of the removed silica to the excess silica, increases with increasing initial seed concentration and increasing temperature. A high silica removal ratio is obtained for relatively low initial silica concentrations (≤0.7 kg-SiO₂·m^–3). When the initial silica concentration is higher, the silica removal ratio is expected to be enhanced by increasing initial seed concentration. The seeding method is suggested to be effective for the removal of silica in actual geothermal brines.