PRECIPITATION OF COLLOID SILICA FROM HYDROTHERMAL SEPARATEBY COAGULANTS ADDITION (KAMCHATKA, RUSSIA)

Abstract

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. —olloid 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.