Precipitation of Amorphous Silica from High-Temperature Hypersaline Geothermal Brines

摘要

A serious problem associated with the conversion of the energy content of hypersaline geothermal systems to electrical power is precipitation of amorphous silica and other phases that can ultimately cause scaling of power plant equipment. The rate of polymerization of monomeric silica is dependent upon pH, temperature, salinity, silica concentration, and the presence of solids. At the Salton Sea Geothermal Field, silica precipitation is promoted by cooling and depressurization. Evolution of CO sub 2 and H sub 2 S causes an increase in residual brine pH, and, as a consequence, monomeric silica polymerizes more rapidly and is co-precipitated with sulfides and hydroxides. However, it may be possible to stabilize silica in geothermal brines by acidification with hydrochloric acid.