Abstract: NORMs are inhibited or prevented from precipitating with scale produced by a hot aqueous solution by adding multiple portions of a crystal structure modifier to the aqueous solution as it cools before and during removal of silicon containing components by precipitation. Preferred crystal structure modifiers include polyacrylate crystal structure modifiers and phosphonomethylated amines.

Abstract: An integrated system of non-condensable gas (NCG) and condensate treatment allows geothermal power plant condensate and non-condensable gas effluent streams containing H.sub.2 S and ammonia to be commercially useful for more than for cooling tower makeup. In the preferred embodiment, the pH of the condensate is increased by adding ammonia and the pH increased stream is contacted with NCG to scrub and oxidize the H.sub.2 S constituent of the NCG. By reducing the pH, the condensate or aqueous stream mixture can also be used to further transfer ammonia from the non-condensable gas stream to the aqueous stream, enriching the stream for use as a fertilizer/irrigation water mixture. If other commercial uses are desired for the mixture and/or oxidized NCG streams, they can be resin treated to remove the ammonia constituent. With the ammonia and H.sub.2 S constituents decreased, the condensate may be used for a variety of applications and the NCG can be injected or used as a commercial feed stream.

Abstract: Geothermal brine and other platinum-containing solutions are passed through a carbon-containing zone to recover platinum from the aqueous medium.

Abstract: Radioactivity and fluoride ion are inhibited or prevented from precipitating in scale formed from a geothermal brine by adding a scale inhibitor to the cooling brine solution. Preferred scale inhibitors include polyacrylate dispersants and phosphonomethylated amines.

Abstract: Radioactivity and fluoride ion are inhibited or prevented from precipitating in scale formed from a geothermal brine by adding a dispersant to the cooling brine solution. Preferred dispersants include polyacrylates and polyphosphonic acids.

Abstract: Soluble salts are prevented from precipitating from a brine concentrate produced from the flashing a geothermal brine by diluting the brine concentrate with preconditioned condensate. The pH of the condensate is first adjusted to within two pH units of brine concentrate. Then concentration of sulfide ion is reduced by oxidizing sulfide to sulfate by exposure to air for a period of time sufficient to oxidize a substantial portion of the sulfide, but short enough to prevent a substantial concentration of oxygen from dissolving in the condensate. The preconditioned condensate is then mixed with the brine concentrate to form an injection stream. The injection stream is then injected into the earth.

Abstract: A geothermal brine containing recoverable metals is contacted with at least two electrodes, across which an electrical potential is applied to cause the metals to deposit upon said electrodes. The invention is particularly useful for the recovery of iron, zinc, lead, and manganese from a brine from a geothermal aquifer such as is found at the Salton Sea in California.

Abstract: The concentration of amorphous silica in an aqueous solution is monitored to determine a concentration above which silica will precipitate. The precipitation concentration is data processed with a means for data processing by solving the Setchnow equation for aqueous solutions containing silica. The means for data processing generates a signal that, if need be, can be used to automatically adjust the parameters of the system to prevent silica precipitation or to carefully control the precipitation rate. An alternative embodiment provides a method for determining amorphous silica concentration, then data processing the solution to the Setchnow equation, generating a signal, and adjusting the parameters of the system. The apparatus and method of this invention are particularly useful in geothermal power plants.

Abstract: Geothermal brine is passed through a zone containing a packing metal so as to reduce its tendency to deposit iron/silica scale, reduce corrosivity of the brine, and/or remove and recover metals from the brine. The method polishes the geothermal brine by contacting the brine with a packing metal higher in the electromotive series than silver for a time sufficient for a precious metals to precipitate onto the packing at brine temperature and pH conditions which inhibit iron-rich silica scale. Most preferably, the contacting is accomplished near an injection well at the end of a heat extraction process and the packing comprises coiled zinc-galvanized steel chicken wire mesh packed in a sufficient density to also act as a filter for suspended particles. Alternatively, contacting is also accomplished near the production well. Dissolving the packing in a suitable acid leaves a precious metal-rich residue behind for subsequent recovery.

Abstract: A method for controlling fouling of a heat exchange surface exposed to a high-enthalpy geothermal brine tending to form silica scale, but containing less than a saturated amount of cations capable of reacting with sulfates. The method adds a limited amount of sulfuric acid to the brine to form a mixture. The amount of sulfuric acid is limited to that required to produce sulfates sufficient to apparently complex with silica, but less than the amount required to increased the sulfates to above saturation amounts of sulfate reacting cations, significantly reducing or virtually eliminating sulfate and silica deposits and fouling. The addition is further controlled to an amount which reduces the pH of the mixture to no less than about 4.5. The addition does not significantly increase corrosion rates of mild steel heat exchanger materials of construction.

Abstract: A process is provided for controlling the emission of nitrogen dioxide from, and the growth of living organisms in, steam condensate cooling towers and catch basins used in conjunction with a condensate of steam derived from an ammonia containing geothermal brine. The process comprises contacting the condensate, in a substantially continuous manner, with a less-than-stoichiometric amount of an oxidizing agent, which results in the oxidation of nitrite in the condensate to a nitrate. The process optionally provides for periodically introducing a biocide into the condensate in an amount which controls organism growth in the cooling tower and catch basin. To prevent system corrosion, the process may include treating the condensate with a non-organic, phosphate-based corrosion inhibitor and scale dispersant.

Abstract: A process for abating the emission of hydrogen sulfide and nitrogen oxide from a condensate of steam, derived from a sulfide- and nitrite-containing geothermal brine, comprising introducing an oxidizing agent into the condensate in an amount less than that which would be required to directly oxidize all the sulfide and nitrite to sulfate and nitrate. The process optionally provides for periodically introducing a biocide into the condensate to control the growth of organism therein.

Abstract: A method is disclosed for polishing geothermal brines containing iron-rich silica scale and silica particles suspended therein while removing and recovering copper, silver and other precious metals dissolved therein. The method comprises passing brine having a pH just below about 5.0 through a conduit packed with a metal higher in the electromotive series than silver for a time sufficient for a substantial portion of the copper and silver therein to precipitate onto the packing. Preferably, the packing comprises coiled zinc-galvanized steel chicken wire mesh packed in a sufficient density to act as a filter for said suspended particles. Dissolving the packing in a suitable acid will leave a precious metal-rich residue behind for subsequent recovery. When the brine is treated in accordance with this method, the useful life of injection wells used to return cooled brine back to the geothermal field is extended by at least about 3 time as compared to that observed with untreated brine.

Abstract: Geothermal brine is passed through a zone containing a packing metal so as to reduce its tendency to deposit iron/silica scale, reduce corrosivity of the brine, and/or remove and recover metals from the brine. The method polished the geothermal brine by contacting the brine with a packing metal higher in the electromotive series than silver for a time sufficient for a precious metals to precipitate onto the packing at brine temperature and pH conditions which inhibit iron-rich silica scale. Most preferably, the contacting is accomplished near an injection well at the end of a heat extraction process and the packing comprises coiled zinc-galvanized steel chicken wire mesh packed in a sufficient density to also act as a filter for suspended particles. Alternatively, contacting is also accomplished near the production well. Dissolving the packing in a suitable acid leaves a precious metal-rich residue behind for subsequent recovery.

Abstract: A method of precipitating metals from a spent geothermal brine containing the same comprises admixing the geothermal brine with a condensate of steam, derived from the brine, in a volume ratio of brine to condensate of 1:2 to 1:10. The invention is particularly applicable to geothermal brine processes for the production of electric power, such as are practiced at the Salton Sea.

Abstract: In the processing of a geothermal brine and the recovery of heat therefrom, there are produced a non-condensable gas stream containing hydrogen sulfide and carbon dioxide and a liquid stream comprising a condensate of steam derived from the brine. In accordance with the present invention, the noncondensable gases are introduced into the condensate in the presence of an oxidizing agent to form a gas-liquid mixture. The mixture is maintained at an alkaline pH for a time sufficient for a substantial portion of the hydrogen sulfide to be oxidized. Thereafter, the mixture is introduced into a gas-liquid separation zone for separate recovery of a gas stream comprising a major amount of carbon dioxide and substantially free of hydrogen sulfide. Advantageously, the recovered gas stream is recycled to the geothermal brine process to reduce the pH of the brine and its scaling potential.

Abstract: A method is disclosed for polishing geothermal brines containing iron-rich silica scale and silica particles suspended therein while removing and recovering copper, silver and other precious metals dissolved therein. The method comprises passing brine having a pH just below about 5.0 through a conduit packed with a metal higher in the electromotive series than silver for a time to sufficient for substantially all of the silver and other precious metals therein to precipitate onto the packing. Preferably, the packing comprises coiled zinc-galvanized steel chicken wire mesh packed in a sufficient density to act as a filter for said suspended particles. Dissolving the packing in a suitable acid will leave a precious metal-rich residue behind for subsequent recovery. When the brine is treated this process, the useful life of injection wells used to return cooled brine back to the geothrmal field is extended by at least about 3 times as compared to that observed with untreated brine.

Abstract: The deposition of metal-containing scale, such as iron silicate scale, from a hot aqueous geothermal brine, or the like, is controlled by blending into the brine sufficient reducing agent effective for reducing trivalent iron and manganese cations in a high temperature brine solution to divalent ions to cause an overall decrease in scale deposition, especially of iron silicate scale. Preferably, from 2 to 7 times the stoichiometric amount of reducing agent is used to effect a 70 to 90 percent reduction in the formation of iron silicate scale.

Abstract: A process is provided for controlling the emission of hydrogen sulfide from, and the growth of living organisms in, steam condensate cooling towers and catch basins used in conjunction with steam and condensate of steam derived from hydrogen sulfide-containing geothermal brine. The process comprises contacting the condensate, in a substantially continuous manner, with a small, substantially less-than-stoichiometric amount of an oxidizing biocide, such as trichloro-isocyanuric acid or oxidizing biocide, such as trichloro-isocyanuric acid or 1-bromo-3-chloro-5,5-dimethyl-hydantoin, which results in the oxidation of such hydrogen sulfide precursors as ammonium bisulfide in the condensate to a water-soluble sulfite and/or sulfate, and which slows the growth of organisms in the cooling tower and catch basin.

Abstract: A process is provided for controlling the emission of nitrogen dioxide from, and the growth of living organisms in, steam condensate cooling towers and catch basins used in conjunction with steam and condensate of steam derived from ammonia and geothermal brine containing dissolved iron. The process comprises contacting the condensate, in a substantially continuous manner, with a small, substantially less-than-stoichiometric amount of an oxidizing biocide, such as trichloroisocyanuric acid or 1-bromo-3-chloro-5,5-dimethyl-hydantoin, which results in the oxidation of said nitrite formed by activity of bacterial in the condensate to a non-reactive nitrate, and which slows the growth of said bacteria in the cooling tower and catch basin. The process additionally includes periodically introducing into the condensate with amounts of a second biocide, such as dodecylguanidine hydrochloride or isothiazalone, which provides most of the control or organism growth in the cooling tower and catch basin.