PRECIPITATION OF COLLOID SILICA FROM HYDROTHERMAL SEPARATE BY COAGULANTS ADDITION ( KAMCHATKA , RUSSIA )
We have carried out the experiments on coagulation and precipitation of silica from the separate of Verkhne-Mutnovsky geothermal electric power plant (Mutnovskoe hydrothermal field). Silica precipitation from the water solution was conducted in two ways: by adding slaked lime CaO and by electrocoagulation treatment on aluminium electrodes. Silica precipitation with addition of slaked lime was carried out under laboratory conditions at the temperature of 20 and 96 °C. Сolloid and monomeric silica concentrations, solution pH, flakes sizes and physical-chemical properties of material precipitated with different quantities of added lime were determined. We also carried out series of experiments on solution treatment of mixed type: addition lime with freshly precipitated flakes, and addition lime with sea water. In the experiments on electric coagulation, current intensity and distance between electrodes were changed. Dependence of silica concentration on treatment duration was studied. Quantities of electric energy and anode aluminium consumed for reducing of silica concentration to a certain level were obtained. The results of our experiments can be used for developing of technological scheme of silica precipitation and utilization optimal for Verkhne-Mutnovsky geothermal electric power plant.
SILICA COAGULATION AND PRECIPITATION IN HYDROTHERMAL SOLUTION ( KAMCHATKA , RUSSIA )
Studied were the processes of coagulation and precipitation of silica in the hydrothermal solution. Experiments were carried out on colloid silica coagulation and precipitation by various types of metal cations. Residual concentrations of silica and cations in the treated solution were determined, as well as pH and amount of Ca, Mg, Al and Fe in the settled material depending upon the coagulants consumption at 20°C and 96°C. Stability of colloid silica in hydrothermal solution was studied, as well as the mechanism of coagulation and precipitation of silica by metal cations.
The recovery of lithium from geothermal water in the Hatchobaru area of Kyushu, Japan.
The recovery of lithium from geothermal water at Hatchobaru in Kyushu, Japan, was investigated. A coprecipitation method using aluminium salts was employed. The lithium concentration in the geothermal water used in the present study was about 10 ppm. To make our experimental results more applicable for geothermal water, a reference lithium solution (10 ppm) was also studied as a control solution. A perfect recovery of lithium was obtained for the reference lithium solution by choosing appropriate conditions. For geothermal water, the yield of Li was not so good as in the control solution. However, an almost complete recovery of lithium was attained for geothermal water by the removal of calcium ions and polymerized silica. The mechanism of Li recovery was also considered.