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Title: Silica recovery and control in Hawaiian geothermal fluids

Abstract

A series of experiments was performed to investigate methods of controlling silica in waste geothermal brines produced at the HGP-A Generator Facility. Laboratory testing has shown that the rate of polymerization of silica in the geothermal fluids is highly pH dependent. At brine pH values in excess of 8.5 the suspension of silica polymers flocculated and rapidly precipitated a gelatinous silica mass. Optimum flocculation and precipitation rates were achieved at pH values in the range of 10.5 to 11.5. The addition of transition metal salts to the geothermal fluids similarly increased the rate of polymerization as well as the degree of precipitation of the silica polymer from suspension. A series of experiments performed on the recovered silica solids demonstrated that methanol extraction of the water in the gels followed by critical point drying yielded surface areas in excess of 300 M{sup 2}/g and that treatment of the dried solids with 2 N HCl removed most of the adsorbed impurities in the recovered product. A series of experiments tested the response of the waste brines to mixing with steam condensate and non-condensable gases.The results demonstrated that the addition of condensate and NCG greatly increased the stability of the silica in themore » geothermal brines. They also indicated that the process could reduce the potential for plugging of reinjection wells receiving waste geothermal fluids from commercial geothermal facilities in Hawaii. Conceptual designs were proposed to apply the gas re-combination approach to the disposal of geothermal waste fluids having a range of chemical compositions. Finally, these designs were applied to the geothermal fluid compositions found at Cerro Prieto, Ahuachapan, and Salton Sea.« less

Authors:
Publication Date:
Research Org.:
Hawaii Univ., Honolulu, HI (United States). Hawaii Inst. of Geophysics
Sponsoring Org.:
USDOE; USDOE, Washington, DC (United States)
OSTI Identifier:
7147695
Report Number(s):
DOE/ID/12741-12
ON: DE92041041
DOE Contract Number:  
FG07-88ID12741
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; GEOTHERMAL POWER PLANTS; WASTE DISPOSAL; SILICON OXIDES; PRECIPITATION; REMOVAL; AHUACHAPAN GEOTHERMAL FIELD; BRINES; CERRO PRIETO GEOTHERMAL FIELD; GEOTHERMAL FLUIDS; KILAUEA VOLCANO; LEACHING; MIXING; POLYMERIZATION; PROGRESS REPORT; RECOMMENDATIONS; SALTON SEA GEOTHERMAL FIELD; TESTING; CHALCOGENIDES; CHEMICAL REACTIONS; DISSOLUTION; DOCUMENT TYPES; FLUIDS; GEOTHERMAL FIELDS; MANAGEMENT; OXIDES; OXYGEN COMPOUNDS; POWER PLANTS; SEPARATION PROCESSES; SILICON COMPOUNDS; THERMAL POWER PLANTS; VOLCANOES; WASTE MANAGEMENT; Geothermal Legacy; 154000* - Geothermal Energy- Waste Management- (1990-)

Citation Formats

Thomas, D M. Silica recovery and control in Hawaiian geothermal fluids. United States: N. p., 1992. Web. doi:10.2172/7147695.
Thomas, D M. Silica recovery and control in Hawaiian geothermal fluids. United States. https://doi.org/10.2172/7147695
Thomas, D M. 1992. "Silica recovery and control in Hawaiian geothermal fluids". United States. https://doi.org/10.2172/7147695. https://www.osti.gov/servlets/purl/7147695.
@article{osti_7147695,
title = {Silica recovery and control in Hawaiian geothermal fluids},
author = {Thomas, D M},
abstractNote = {A series of experiments was performed to investigate methods of controlling silica in waste geothermal brines produced at the HGP-A Generator Facility. Laboratory testing has shown that the rate of polymerization of silica in the geothermal fluids is highly pH dependent. At brine pH values in excess of 8.5 the suspension of silica polymers flocculated and rapidly precipitated a gelatinous silica mass. Optimum flocculation and precipitation rates were achieved at pH values in the range of 10.5 to 11.5. The addition of transition metal salts to the geothermal fluids similarly increased the rate of polymerization as well as the degree of precipitation of the silica polymer from suspension. A series of experiments performed on the recovered silica solids demonstrated that methanol extraction of the water in the gels followed by critical point drying yielded surface areas in excess of 300 M{sup 2}/g and that treatment of the dried solids with 2 N HCl removed most of the adsorbed impurities in the recovered product. A series of experiments tested the response of the waste brines to mixing with steam condensate and non-condensable gases.The results demonstrated that the addition of condensate and NCG greatly increased the stability of the silica in the geothermal brines. They also indicated that the process could reduce the potential for plugging of reinjection wells receiving waste geothermal fluids from commercial geothermal facilities in Hawaii. Conceptual designs were proposed to apply the gas re-combination approach to the disposal of geothermal waste fluids having a range of chemical compositions. Finally, these designs were applied to the geothermal fluid compositions found at Cerro Prieto, Ahuachapan, and Salton Sea.},
doi = {10.2172/7147695},
url = {https://www.osti.gov/biblio/7147695}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jun 01 00:00:00 EDT 1992},
month = {Mon Jun 01 00:00:00 EDT 1992}
}