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 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 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.