Separation of silica from spent geothermal fluids by adsorptive bubble techniques
A method is described for the separation of amorphous silica from super-saturated high ionic strength geothermal fluids produced by the Hawaii Geothermal Project Well-A. A bench-scale technique which makes use of adsorptive bubble flotation is employed to remove silica after flocculation by the addition of polyvalent metal ions to hot (60-90/sup 0/C) spent brine discharge. Ferric and aluminum salts are evaluated as flocculants under varying conditions. The anionic surfactant sodium lauryl sulfate and the cationic surfactant lauryl amine hydrochloride (LA) are utilized as the collectors below and above the isoelectric point, respectively. Efficiency of removal of the silica is pH, metal concentration, and surfactant-type dependent. Best results are achieved under slightly alkaline conditions (pH = 8), using 3.75 x 10E/sup -4/ M ferric ion present as its sulfate, La as the collector, and with a gas flow of 15 +/- 3 mL/min. Under these conditions, approximately 70 +/- 2% of the total silica is separated from the brine discharge; this value, although not quantitative, represents more than 85% removal of the silica present above its amorphous solubility at the operating temperature. After the separation process, fluids contain residual concentrations of silica which are not expected to result in scale deposition and which can then be passed through heat exchangers to extract further energy for secondary uses.
- Research Organization:
- Univ. of Hawaii, Honolulu
- OSTI ID:
- 6014929
- Journal Information:
- Sep. Sci. Technol.; (United States), Journal Name: Sep. Sci. Technol.; (United States) Vol. 22:4; ISSN SSTED
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
150600 -- Geothermal Energy-- Environmental Aspects
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400105* -- Separation Procedures
520200 -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ADSORPTION
BENCH-SCALE EXPERIMENTS
BRINES
BUBBLES
COLLOIDS
DATA
DISPERSIONS
EXPERIMENTAL DATA
FLOCCULATION
FLOTATION
FLUIDS
GEOTHERMAL FLUIDS
INFORMATION
NUMERICAL DATA
PH VALUE
PRECIPITATION
QUANTITY RATIO
SEPARATION PROCESSES
SORPTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES
SURFACTANTS