Abstract: The present invention provides a novel method of extracting zinc from geothermal brines and synthetic brines which can be performed in a continuous, in-line process.

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: Geothermal brines are passed through a bed of an anionic resin selective to the removal of boron while maintaining a pH value between about 4 to 5.5 to load the boron on the resin from which the boron is thereafter recovered. If the brine contains large quantities of constituents have Lewis acidities greater than boric acid, these constituents are preferably removed before the boron is recovered. The invention is particularly applicable to geothermal brines of temperature above ambient, e.g., 90.degree. C. and above, such as 95.degree. C. and above.

Abstract: Disclosed is an efficient biological process for recovering heavy metals from refractory manganiferous ore, and a process for removing heavy metal contaminants from the soil. The process utilizes manganese reducing Bacillus sp. Specifically exemplified is a novel microbe designated Bacillus MBX 69, or mutants thereof, and the known microbe Bacillus polymyxa, which is disclosed in U.S. Pat. No. 5,055,130. Further, gene(s) encoding the enzyme(s) obtainable from the said bacteria can be used by placing such gene(s) on a suitable vector and transforming a competent host. The transformed host then can be used in the same manner as the native microbe. Also, the enzyme(s) themselves can be used in the above-described processes.

Abstract: A bacterial-assisted heap leach process is employed for the solubilization of a metal from a refractory ore containing fines and/or clay wherein at least a portion of the metal is solubilized by the bacterial oxidation of sulfides and the concomitant or sequential dissolution of the metal into a leaching solution. For some metals, the leaching solution has a pH of greater than about 9. The improvement in the process includes the application of an aqueous solution of acrylamide polymer to the ore in an amount effective to agglomerate the fines and/or clay prior to heap formation. The acrylamide polymer has a molecular weight of at least 500,000 and is comprised of from about 0 to about 100 mole percent of (meth)acrylamide mer units and from about 0 to 100 mole percent of N-sulfoalkyl(meth)acrylamide mer units. The acrylamide polymer is preferably applied to the ore as an aqueous solution formed at least in part by recycled bio solution.

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: A method of cleaning debris, which involves the separation of heavy metals and oils, simultaneously, from the debris, which debris is primarily an inert substance, such as soil from a coking plant. The process employs acetic anhydride, which is mixed with the debris, for removing any moisture. After the addition of acetic anhydride, aqueous acetic acid is distilled off. The remaining distilland is then filtered to remove the heavy metals and oils from the debris.

Abstract: The agglomeration of gold or silver ore fines is improved by the use of a water-soluble vinyl polymer as the agglomerating agent.

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: A process for eluting gold-iodine complex from an ion-exchange resin, characterized by adding sulfuric acid and sodium nitrite to the gold-iodine complex adsorbed on the resin, and adding sodium sulfite as an eluant. The process is particularly useful for eluting gold-iodine complex adsorbed on strongly basic anion-exchange resin, such as washings resulting from the washing of leach residue which has been passed through the resin.

Abstract: Apparatus for concentrating gold-containing particulate material includes a housing containing an endless conveyor belt the upper stretch of which is inclined in the direction of its movement. An infeed hopper adjacent the upper end of the belt functions to deposit gold-containing particulate material on the upwardly moving upper stretch of the belt, and said stretch is inclined sufficiently to cause the particulate material to move downwardly over the upwardly moving upper stretch in a manner to effectuate classification of the particulate material by gravity separation into a minor fraction of valuable particles of smaller size and heavier specific gravity, including fine and microfine gold particles, and a major fraction of tailings particles of larger size and lighter specific gravity.

Abstract: A system for heap leach mining comprises supply and header pipes for conducting leaching solution alongside a bed or "heap" of crushed metal-laden ore deposited on an impervious pad. A series of spaced tubes are connected to the supply header pipes to extend transversely thereof, over the pad, to receive the leaching solution therefrom. A plurality of emitters are connected in spaced relationship along each of the tubes for emitting the leaching solution at a controlled and substantially uniform rate over the pad and into the ore bed. The tubes and emitters can be positioned either on an upper surface of the ore bed or buried beneath such surface, at a predetermined depth. The system and method of this invention provide numerous advantages over conventional surface spraying systems and methods, including substantial cost savings thereover.

Abstract: A process for purifying gold-bearing iodine lixiviant characterized by bringing the gold-bearing lixiviant into contact with a strongly acidic cation-exchange resin to selectively adsorb heavy metals while allowing gold and iodine to pass therethrough. The process is particularly useful for purifying gold-bearing iodine lixiviant prior to recovering the gold by electrolysis.

Abstract: A system for heap leach mining comprises supply and header pipes for conducting leaching solution alongside a bed or "heap" of crushed metal-laden ore deposited on an impervious pad. A series of spaced tubes are connected to the supply header pipes to extend transversely thereof, over the pad, to receive the leaching solution therefrom. A plurality of emitters are connected in spaced relationship along each of the tubes for emitting the leaching solution at a controlled and substantially uniform rate over the pad and into the ore bed. The tubes and emitters can be positioned either on an upper surface of the ore bed or buried beneath such surface, at a predetermined depth. The system and method of this invention provide numerous advantages over conventional surface spraying systems and methods, including substantial cost savings thereover.

Abstract: A system for heap leach mining comprises supply and header pipes for conducting a leaching solution alongside a bed or "heap" of crushed metal-laden ore deposited on an impervious pad. A series of spaced tubes are connected to the supply and header pipes to extend transversely thereof, over the pad, to receive the leaching solution therefrom. A plurality of emitters are connected in spaced relationship along each of the tubes for emitting the leaching solution at a controlled and substantially uniform rate over the pad and into the ore bed. At least some of the emitters are adjustable whereby different sets of flow passages can be utilized. The adjustable emitter comprises a sleeve slip-fit and rotatably mounted in a housing for rotative adjustment between at least two positions to alternately communicate the sets of flow passages with an inlet to the emitter.