ROCK - WATER INTERACTION IN HOT DRY ROCK GEOTHERMAL SYSTEMS
Minerals likely to be components of HDR geothermal energy recovery systems investigated experimentally with respect to their hydrous heat exchange media. It was shown that both mafic (enstatite, aegirine-augite, hornblende) and salic (lepidolite mica, albite) minerals react with aqueous fluids according to the simple scheme in which H**+ ions are exchanged by metal cations. Acidity and liquid composition were found to be the most important factors influencing degree and rate of reaction. Extraction of components from solids usually occurs in an incongruent way. The original surfaces are changed either by selective leaching or by deposition of secondary phases. Trace element determinations confirm this conclusion. The layers formed by these processes are inhibitory to further reactions. Thermodynamically unstable minerals have higher reaction rates than more stable ones. In rocks the mixtures of minerals react according to different mechanisms. The decomposition rates of less quickly leached phases are depressed by the constituents delivered by fastly reacting minerals. By these processes the behaviour of HDR systems is determined. Leaching rates and composition mechanisms can be changed at will by adjusting fluid compositions to the processes wanted.
Bibliographic Reference: EUR 10176 EN (1985), MF, 60 P., BFR 150, BLOW-UP COPY BFR 300, EUROFFICE, LUXEMBOURG, POB 1003
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Record Number: 1989124081200 / Last updated on: 1987-01-01
Available languages: en