Geothermal Brine

The major contributor to scaling is silica. Supersaturation is created as a result of 

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Brine Sources. Lithium occurs naturally in brines from salars, saline lakes and seawater, od-fteld waters, and geothermal brines. Of these sources, lithium is produced only from brines of two salars. 

Demonstrated reserve quantities are estabUshed by measurements including drillings surface sampling, etc. Inferred reserves are those derived from geological survey information, not by measurement of the extent of the particular reserve. Not included herein are identified marginal and speculative resources, such as the oil-field and geothermal brines and lithium-hearing clays. These latter reserves are speculative as to extent, not existence. Total undiscovered clays in the western United States are speculatively estimated at 15 x 10 t lithium (16). More detailed Hsts of reserves are also available (15,17). 

The eost of produeing power varies with the eapaeity and temperature of geothermal brine and the eooling method seleeted. For illustration purposes, the estimate of the installed eost of a binary eyele geothermal plant is l,500/kW -i- 250,000. Using an average revenue of 0.07 per kW/hr, a 1 MW geothermal plant will have a three-year paybaek period. 

Swearingen, J. S., Power From Hot Geothermal Brines, Chemical Engineering Progress, July 1977. 

From the corrosion point of view, it is very important to control the deposition of scale. Removal of deposited scale by mechanical means is the first step. Standard, industrial water-treating techniques can be used to control scale deposition in general. In deep, hot wells or geothermal wells it is best to avoid untreated makeup water (i.e., geothermal brines). 

A. C. "Study of Silica Scaling from Geothermal Brines," EIC Corp. Prog. Rep. March-September 1976, C00-2607-3. 

Walters [24] examined the effect of chloride on the use of bromide and iodide solid state membrane electrodes, and he calculated selectivity constants. Multiple linear regression analysis was used to determine the concentrations of bromide, fluorine, and iodide in geothermal brines, and indicated high interferences at high salt concentrations. The standard curve method was preferred to the multiple standard addition method because of ... 

Silvester, L. F. and K. S. Pitzer, "Thermodynamics of Geothermal Brines, I. Thermodynamic Properties of Vapor-Saturated NaCl(ag) Solutions From 0-300 °C,"... 

The PVT properties of aqueous solutions can be determined by direct measurements or estimated using various models for the ionic interactions that occur in electrolyte solutions. In this paper a review will be made of the methods presently being used to determine the density and compressibility of electrolyte solutions. A brief review of high-pressure equations of state used to represent the experimental PVT properties will also be made. Simple additivity methods of estimating the density of mixed electrolyte solutions like seawater and geothermal brines will be presented. The predicted PVT properties for a number of mixed electrolyte solutions are found to be in good agreement with direct measurements. 

A recent report on the recovery of metal values from geothermal brine indicated the presence of lead, silver, copper, and iron in the cationic form. Because the brine contained 155 g/1 of chloride the metals must be present as chloroanions. The presence of chloroanions rather than equated cations suggests a different type of processing and would certainly alter the results of thermodynamic estimates. 

Badruk, M. Kabay, N. 2003. Removal of boron from Kizildere-Denizli geothermal brines using ion-exchange method. In Proceedings International Conference on Multiple Integrated Uses of Geothermal Resources, Reykjavik. 14-17 September, S14, 8-13. 

Li ndal, B. 1975. Development of industry based on geothermal energy, geothermal brine, and sea water in the Reykjanes Peninsula, Iceland. In Proceedings Second United Nations Symposium on the Development and Use of Geothermal Resources, San Francisco, 20-29 May 1975, 2223-2228. 

White, D. E., Anderson, E. T. Grubbs, D. K. 1963. Geothermal brine well Mile deep drill hole may tap ore-bearing magmatic water and rocks undergoing metamorphism. Science, 139, 919-922. 

Clutter, T. 2000. Mining economic benefits from geothermal brine. Geo-Heat Center Quarterly Bulletin, 21, 1 -3. 

Titanium alloys suffer crevice corrosion in hot aqueous chloride media, but the alloy containing molybdenum, 3A1-8V-6 Cr-4Zr-4 Mo has good resistance to crevice corrosion and is successfully used in hot sour well and geothermal brine... 

In saline soils and soils contaminated with geothermal brines, the ionic strengths of the soil solution may exceed 0.5 M. This fact poses the necessity of using equations which have been developed to describe the activity coefficients of ions in concentrated, multicomponent electrolyte solutions. As part of a study on the chemistry of ore-forming fluids, Helgeson (50) has proposed that the true individual ion activity coefficients for ions present in small concentrations in multicomponent electrolyte solution having sodium chloride as the dominant component be approximated by a modified form of the Stokes-Robinson equation. The equation proposed is ... 

According to Helgeson (50), equation 8 can be used to estimate the individual ion activity coefficient for ions present in small concentrations in sodium chloride solutions of true ionic strength up to 3.0 M. Since saline soils and geothermal brines are often dominated by sodium chloride, it will be appropriate to use the equation proposed by Helgeson (50). Therefore, in GEOCHEM, ionic activity coefficient calculations for such systems are performed by equation 8. 

Miller, D. G., Piwinskii, A. J. and Yamauchi, R. The use of geochemical-equilibrium computer calculations to estimate precipitation from geothermal brines, UCRL-52197 Livermore, Calif., 34 p., (1977). 

Doe B. R., Hedge C. E., and White D. E. (1966) Preliminary investigation of the source of lead and strontium in deep geothermal brines underlying the Salton Sea geothermal area. Econ. Geol. 61, 462-483. 

Geothermal brine or a mixture of brine and steam is delivered to a flash vessel at the power plant by either natural circulation or pumps in the production wells. At the entrance to the flash vessel, the pressure is reduced to produce flash steam. The steam is delivered to the high-pressure inlet to the turbine. The remaining brine drains to another flash vessel where the pressure is again reduced to produce low-pressure flash steam. 

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