Abstract: A process for recovering a base metal from a material, the base metal being selected from cobalt, copper, nickel and zinc, the process comprising the steps of reacting the host material with a ferric ion species in a leach solution, at conditions sufficient to cause at least a portion of the base metal to be oxidized by the ferric ion species, thereby causing the ferric ion species to be converted to a ferrous ion species, and oxidizing the ferrous ion species with an oxidation mixture of SO2 and oxygen to form the ferric ion species for subsequent reaction with the material.

Abstract: The process of the present invention recovers precious metals from refractory carbonaceous precious metal ores by floating a portion of the ground ore, blending the concentrate with an unfloated portion of the ore, autogenously autoclaving the blended material, cooling the oxidized slurry by dilution, leaching the oxidized slurry after dilution in the presence of a thiosulfate lixiviant, and recovering the precious metal by suitable techniques.

Abstract: A system for recovery of metals from solutions containing dissolved metals. The system includes an apparatus and method for placing supercritical carbon dioxide that contains an extractant in contact with the solution and agitating the two resulting phases. Once the metals are extracted by the extractant, they can be removed from the carbon dioxide phase by depressurization or by reduction by exposure to hydrogen. The extractant preferably comprises a metal binding group, a spacer group and a C02-philic group.

Abstract: A method and apparatus for bioprocessing particles wherein particles are entrapped a porous material and have biologically active microorganisms on their surfaces. A liquid (carrying oxygen and/or nutrients for said microorganisms) is passed through the entrapped particles and microorganisms and microorganisms are active to breakdown said particles. After a suitable period of time the particles are removed from the matrix.

Abstract: The process of the present invention “jump starts” heap biooxidation of sulfides by incorporating a previously biooxidized material into the heap. The process can be used to recover precious and/or base metals from sulfidic ores and concentrate.

Abstract: A process is disclosed for the recovery of gold and/or silver values from activated carbon, wherein they are adsorbed as cyanide complexes. The process uses an eluant containing sugar. The process allows the eluant to pass through fresh carbon twice, thereby reducing the volume of the gold-loaded eluant. This, in turn, reduces the size of the electrowinning or zinc precipitation circuits. The process also improves elution efficiency when barren electrowinning solution is recycled in the elution process.

Abstract: A method of biotreating a solid material to remove an undesired compound using a nonstirred surface bioreactor is provided. According to the method the surface of a plurality of coarse substrates is coated with a solid material to be biotreated to form a plurality of coated coarse substrates. The coarse substrates have a particle size greater than about 0.3 cm and the solid material to be biotreated has a particle size less than about 250 .mu.m. A nonstirred surface reactor is then formed by stacking the plurality of coated coarse substrates into a heap or placing the plurality of coated coarse substrates into a tank so that the void volume of the reactor is greater than or equal to about 25%. The reactor is inoculated with a microorganism capable of degrading the undesired compound in the solid material, and the solid material is then biotreated in the surface bioreactor until the undesired compound in the solid material is degraded to a desired concentration.

Abstract: A method of recovering precious metal values from refractory sulfide ores is provided. The method includes the steps of separating clays and fines from a crushed refractory sulfide ore, forming a heap from the refractory sulfide ore, producing a concentrate of refractory sulfide minerals from the separated fines and adding the concentrate to the heap, bioleaching the heap to thereby oxidize iron sulfides contained therein, and hydrometallurgically treating the bioleached ore to recover precious metal values contained therein.

Abstract: A method for reclaiming a metallic material from a article including a non-metallic friable substrate. The method comprising crushing the article into a plurality of pieces. An acidic solution capable of dissolving the metallic material is provided dissolving the metallic material in the acidic material to form an etchant effluent. The etchant effluent is separated from the friable substrate. A precipitation agent, capable of precipitating the metallic material, is added to the etchant effluent to precipitate out the metallic material from the etchant effluent. The metallic material is then recovered.

Abstract: A method for refining noble metals has a silver treating process including a nitric acid leaching step of silver, a purification step of the leaching solution, an electrolytic decomposition step of silver, and a recycling step after the electrolytic decomposition, wherein in the purification step, lime is added in order to precipitate the metallic impurities, such as selenium, tellurium, bismuth, and copper, by neutralization of the leaching solution, and in the recycling step, sulfuric acid is added to the solution after electrolytic decomposition to regenerate nitric acid for recycling use by precipitation of calcium in the solution as gypsum. Preferably, the refining method has a gold recovery process, as well as the silver treating process, wherein the residue of the nitric leaching of the crude silver is dissolved by chlorination and gold is recovered from the leaching solution by solvent extraction or reductive precipitation.

Abstract: A wear-resistant flash tank pressure let down nozzle for use in passing an ore slurry into an ore slurry flash tank to release steam from the slurry and reduce the pressure of the slurry. The nozzle has an expansion cone flaring toward the discharge end of the nozzle. The cross-sectional area of a choke section of the nozzle and the exit diameter of the expansion cone are selected to establish a relationship between pressure upstream of the nozzle and pressure in the flash tank so that underflashing, overflashing, and shock waves inside the flash tank are minimized.

Abstract: A metal-containing refractory ore, such as refractory sulfide ore, is split into a first portion and a second portion. The first portion is partially biodigested by a sulfide-digesting microorganism in a biooxidation reactor where the microorganism is acclimated to the sulfide "diet" provided by the ore. The partially digested ore is then combined with the second portion. The resulting material is then dewatered, agglomerated, biooxidized and subjected to a lixiviation process.

Abstract: A method for improving the heap biooxidation rate of refractory sulfide ore particles that are at least partially biooxidized using a recycled bioleachate off solution is provided.

Abstract: A process for treating ores or rocks is provided. The process comprises (1) combining the ores or rocks with an acid passivating agent to produce a first combination; (2) contacting the first combination with an aqueous solution comprising (a) manganate ions or source thereof and (b) a base whereby a second combination is produced; and (3) maintaining the pH of the second combination at about 11 to about 13.5. The process can also comprise (1) contacting the ores or rocks with the aqueous solution to produce a third combination; (2) contacting the third combination with an acid passivating agent to produce a fourth combination; and (3) maintaining the pH of the fourth combination at about 11 to about 13.5. The process can be used to prevent acid rock drainage of metal-bearing rocks or to produce a pretreated ore or rock which can further be contacted with a lixiviating agent such as, for example, sodium cyanide to extract metals such as, for example, gold and silver from the pretreated ore or rock.

Abstract: A method of biooxidizing sulfide minerals in a nonstirred bioreactor is provided. According to the disclosed method, a concentrate of sulfide minerals is coated onto a substrate, such as coarse ore particles, lava rock, gravel or rock containing mineral carbonate as a source of CO.sub.2 for the biooxidizing bacteria. After the sulfide minerals are coated onto the substrate, a heap is formed with the coated substrates or the coated substrates are placed within a tank. The sulfide minerals are then biooxidized to liberate the metal value of interest. Depending on the particular ore deposit being mined, the sulfide mineral concentrates used in the process may comprise sulfide concentrates from precious metal bearing refractory sulfide ores or they may comprise sulfide concentrates from metal sulfide type ores, such as chalcopyrite, millerite or sphalorite.

Abstract: A process for reducing boron and/or fluoride ion content of water. Feed water is contacted, in the presence of magnesium, with an alkaline hydroxide to produce treated water and a magnesium precipitate containing boron and fluorine. The precipitate is separated from the treated water. The boron content of water is reducible from above about 0.8 mg/L to below about 0.7 mg/L, and the fluoride ion content is reducible from above about 1 mg/L to below about 0.9 mg/L. The magnesium precipitate is optionally used to neutralize pressure oxidized ore slurry or roaster calcine in the context of gold recovery operations.

Abstract: A process and system and for extracting and refining gold from ores using relatively benign and inexpensive chemicals, fewer process steps, and permitting the recycling and re-use of process chemicals. The invention is preferably implemented as a two part process. In a first part process, gold is extracted from the ore and dissolved in a chemical solution to form a gold complex. The chemical solution preferably includes a KI and I.sub.2. Optionally, Isopropyl alcohol is mixed with the KI and I.sub.2 to serve as an accelerate. In a second part process, the complex is reduced to gold from the solution, preferably by one of two methods. The first method precipitates the gold complex by washing and decomposing of the gold complex to form pure gold. The second method electrolytically plates the gold from the gold complex solution onto a cathode to obtain pure gold.

Abstract: A method and apparatus for anaerobic oxidation of metal sulfides in ores and concentrates. Base-metal and precious-metal ores and concentrates often contain metal sulfides, such iron sulfides (e.g., pyrite, pyrhotite, arsenopyrite, etc.), copper sulfides (e.g., chalcopyrite, chalcocite, etc.), zinc sulfides (e.g., sphalerite, etc.) and/or lead sulfides (e.g., galena, etc.) and/or other metal sulfides), that must be oxidized in order to recover metal values (e.g., gold, silver, or platinum group elements) from the ores. In the present invention, these metal sulfides are oxidized in one reactor under anaerobic or anoxic conditions using oxidized metal ions, such as ferrous ions (Fe.sup.+3), as the oxidizing agent. Anaerobic oxidation of elemental sulfur that is produced by metal sulfide oxidation is biocatalyzed by sulfur-oxidizing bacteria, such as Thiobacillus ferrooxidans, Thiobacillus thiooxidans, or or Sulfolobus sp.

Abstract: A treatment of metallurgical dust and recovery of valuable chemical commodities, comprising the steps of: leaching salts from the dust with water to create a washed EAF dust; reacting the washed EAF dust in a nitric acid solution resulting in a nearly complete dissolution of the zinc, cadmium, copper, magnesium, calcium, manganese and lead from a filtrate; removing iron from the filtrate by raising pH in the system with basic zinc carbonate; removing cadmium, copper and lead in an electrolytic cell, where copper and cadmium are collected at the cathode, and lead is collected at the anode; evaporating and decomposing the filtrate to obtain metal oxides and anhydrous calcium nitrate; leaching the solid residue with water to separate calcium nitrate in a marketable form; removing the zinc from the magnesium and manganese by leaching the residue with an amine solution; stripping the filtrate of ammonium carbonate to yield zinc precipitated as a zinc oxycarbonate; dividing the zinc oxycarbonate into a first stream

Abstract: Recovery of gold from alkaline cyanide leach solutions using ion exchange adsorbents, comprising (a) contacting the cyanide leach solution containing the gold with an extraction reagent comprised of a solid adsorbent carrying an organic base functionality of a compound having a pK.sub.a between about 9-14, such as a guanidyl functionality, to adsorb gold and eluting the adsorbed gold from the solid adsorbent with an aqueous alkaline eluant solution having a pH above about 12 and containing an alkali metal salt of an aromatic or aliphatic carboxylic acid having from about 4-14 carbon atoms, the eluant solution having incorprated therein from about 0.001 moles to about 0.2 moles per liter of an alkali metal cyanide salt. The solid adsorbent containing the aurocyanide complex may be contacted with a concentrated aqueous solution of a zinc tetracyanide salt whereby the aurocyanide complex is displaced with a zinc tetracyanide complex before treatment with the eluant solution.

Abstract: A metal-containing refractory sulfide ore is split into a first portion and a second portion. The first portion is partially biodigested by a sulfide-digesting microorganism in a biooxidation reactor where the microorganism is acclimated to the sulfide "diet" provided by the ore. The partially digested ore is then combined with the second portion. The resulting material is then dewatered, biooxidized and subjected to a lixiviation process.

Abstract: A process for the extraction of a metal from an ore or concentrate comprises subjecting the ore or concentrate to pressure oxidation in the presence of oxygen and an acidic solution containing halogen ions and a source of bisulphate or sulphate ions, such as H.sub.2 SO.sub.4. The metals which can be extracted by the process comprises copper, as well as non-cuprous metals, such as zinc, and precious metals, such as gold and silver.

Abstract: A process for the extraction of zinc from a sulphide ore or concentrate containing copper and zinc includes subjecting the concentrate to pressure oxidation in the presence of oxygen and an acidic halide solution to obtain a resulting pressure oxidation slurry and subjecting the slurry to a liquid/solid separation step to produce a liquor containing copper and zinc in solution. The liquor containing the copper and zinc is subjected to a first solvent extraction with a copper extractant to remove copper from the solution and to produce a copper depleted raffinate. The copper depleted raffinate is subjected to a second solid extraction with a zinc extractant to produce a zinc depleted raffinate and the zinc depleted raffinate is recycled to the pressure oxidation step.

Abstract: A method for improving the recovery of gold and silver from precious metal ore is disclosed. The method comprises contacting precious metal ore with an aqueous solution containing certain fluoroaliphatic surfactants.

Abstract: A method of recovering precious metal values from refractory sulfide ores is provided. The method includes the steps of separating clays and fines from a crushed refractory sulfide ore, forming a heap from the refractory sulfide ore, bioleaching the heap to thereby oxidize iron sulfides contained therein, and hydrometullurgically treating the bioleached ore to recover the precious metal values. If sufficient quantity of precious metal values are contained in the separated clays and fines, these materials can be further processed to recover the precious metal values contained therein.

Abstract: A process for treatment of precious metal ores in which gold is leached from an oxidized ore slurry using a thiosulfate salt lixiviant and copper catalyst. Gold and copper are subsequently loaded onto an ion exchange resin. Copper is recovered from the resin by elution with a thiosulfate solution; gold is recovered from the resin by elution with a thiocyanate colution. Gold is recovered from the eluate by precipitation, electrowinning, or cementation.

Abstract: A method for improving the heap biooxidation rate of refractory sulfide ore particles that are at least partially biooxidized using a recycled bioleachate off solution is provided.

Abstract: A powerful reducing agent such as hydrazine monohydrate is added to the standard eluent solutions such as NsOH-NaCN with or without alcohol. The kinetics of elution of gold or of silver are thus markedly enhanced.

Abstract: A method of biotreating a solid material to remove an undesired compound using a nonstirred surface bioreactor is provided. According to the method the surface of a plurality of coarse substrates is coated with a solid material to be biotreated to form a plurality of coated coarse substrates. The coarse substrates have a particle size greater than about 0.3 cm and the solid material to be biotreated has a particle size less than about 250 .mu.m. A nonstirred surface reactor is then formed by stacking the plurality of coated coarse substrates into a heap or placing the plurality of coated coarse substrates into a tank so that the void volume of the reactor is greater than or equal to about 25%. The reactor is inoculated with a microorganism capable of degrading the undesired compound in the solid material, and the solid material is then biotreated in the surface bioreactor until the undesired compound in the solid material is degraded to a desired concentration.

Abstract: A method for improving the heap biooxidation rate of refractory sulfide ore particles that are at least partially biooxidized using a recycled bioleachate off solution is provided.

Abstract: Metallic forms of gold and other precious metals can be dissolved and transported (mined) using an aqueous sulfide-bearing leach solution. Maximum sulfur fugacities are achieved in sulfide-bearing solutions under approximately neutral pH and relatively reducing conditions. The optimum chemical conditions are achieved specifically by heating an aqueous sulfide solution such as NaHS, Na.sub.2 S, H.sub.2 S, (NH).sub.4 S, or other suitable forms to temperatures of at least about 100.degree. C. in the presence of excess elemental sulfur. The sulfide dissociates in the solution to form aqueous sulfide species including polysulfide and HS.sup.- which lixivate gold and other precious metals.

Abstract: A method of recovering precious metal values from refractory sulfide ores is provided. The method includes the steps of separating clays and fines from a crushed refractory sulfide ore, forming a heap from the refractory sulfide ore, producing a concentrate of refractory sulfide minerals from the separated fines and adding the concentrate to the heap, bioleaching the heap to thereby oxidize iron sulfides contained therein, and hydrometallurgically treating the bioleached ore to recover precious metal values contained therein.

Abstract: A method and apparatus for extraction of precious metals from their ores and the product thereof. Oxidized ore comprising a precious metal is exposed to a leaching solution (lixiviant) comprising a relatively high concentration (fugacity) of dissolved hydrogen sulfide gas, a relatively high concentration (activity) of bisulfide ions, and a relatively low concentration (fugacity) of dissolved hydrogen gas. The hydrogen sulfide gas and bisulfide ions are preferably added to the solution by sulfate-reducing bacteria growing in a medium comprising dissolved sulfate ions and dissolved nitrate ions, but abiotic sources may also be used. Examples of such bacteria include mesophilic, fresh-water species such as Desulfobacterium catecholicum DSM 3882 and Desulfovibrio simplex DSM 4141; mesophilic, salt-water species such as Desulfovibrio salexigens DSM 2638; and thermophilic, fresh-water species such as Desulfomaculum kuznetsovii VKM B-1805. The complexed precious metal is recovered from the lixiviant.

Abstract: A method for recovering precious metals from carbonaceous ore comprising leaching the ore with a lixiviant solution and then preg-robbingly concentrating the precious metal-lixiviant complexes in solution on to the native carbonaceous component of the ore for subsequent recovery. The preg-robbing capacity of the native carbonaceous component of the ore can be augmented by adding recycled carbonaceous matter or finely ground carbon to the ore-lixiviant mixture. Furthermore, after the carbonaceous component of the ore is separated from the gangue, the gangue material can be treated in a hot CIL process to further increase the recovery of the precious metal.

Abstract: A method of recovering precious metal values from refractory sulfide ores is provided. The method includes the steps of separating clays and fines from a crushed refractory sulfide ore, forming a heap from the refractory sulfide ore, bioleaching the heap to thereby oxidize iron sulfides contained therein, and hydrometullurgically treating the bioleached ore to recover the precious metal values. If sufficient quantity of precious metal values are contained in the separated clays and fines, these materials can be further processed to recover the precious metal values contained therein.

Abstract: The present invention, relates to the recovery of zinc values from an acidic solution containing hydrocyanic acid. The zinc is recovered as complex zinc cyanide anions which may, if desired, be recycled for the (selective) preliminary removal or separation of adsorbed copper values from an (strong or weak base) anion exchange material, the anion exchange material additionally being loaded with adsorbed cyanide complexes of precious metal values such as gold and silver. The invention, further relates to the recovery of cyanide values associated with copper cyanide complexes which are adsorbed on or taken up by an (strong or weak base) anion exchange material; the recovered cyanide values, for example, being available for recycling to a cyanide leach stage for leaching additional metal values from an ore or the like.

Abstract: This invention provides an improved method of leaching precious and base metal values from ore comprising contacting a metal-bearing ore or ore concentrate with an oxidizing gas solution comprising a solution of an oxidizing gas dissolved in a perfluorinated liquid, said contact being made prior to or during extraction of the precious or base metal from the ore. In another aspect, this invention provides a method of destroying cyanide from a cyanide-containing solution comprising contacting said solution with a solution of an oxidizing gas dissolved in a perfluorinated liquid.

Abstract: A process is provided for pretreating iron-containing sulfidic ores of precious metals or other such sulfidic rocks with a source of manganate ions prior to lixiviation to form a layer of manganese oxide, thereby reducing the consumption of lixiviation reagents or reducing acid rock drainage.

Abstract: A method of recovering precious metal values from refractory sulfide ores is provided. The method includes the steps of separating clays and fines from a crushed refractory sulfide ore, forming a heap from the refractory sulfide ore, producing a concentrate of refractory sulfide minerals from the separated fines and adding the concentrate to the heap, bioleaching the heap to thereby oxidize iron sulfides contained therein, and hydrometallurgically treating the bioleached ore to recover precious metal values contained therein.

Abstract: Platinum group metals and rhenium are extracted from their elemental state, complex ores, and other materials such as catalysts by leaching them with a solution containing ammonium halogen salts--iodide and bromide in the presence oxygen and/or sulfuric acid. The invented process is particularly effective for spent catalysts containing precious metals and rhenium in an autoclave at a temperature of 50.degree. C.-300.degree. C.

Abstract: A process for recovering gold in which an ore slurry of refractory sulfidic and refractory carbonaceous ore having preg-robbing characteristics due to the presence of organic carbon is subjected to pressure oxidation in an autoclave. The oxidized ore slurry is mixed with a thiosulfate salt lixiviant, which mixture is maintained at a pH between 7 and 8.7 while the slurry is agitated in a stirred tank reactor system having agitated leach tanks. Gold is recovered from the gold-bearing leachate by cementation, adsorption on an adsorbent, or cyanidation.

Abstract: An oxidation process uses an inclined raceway which has a plurality of longitudinally spaced transverse riffles across the raceway so that a slurry of water and particles to be oxidized runs over the raceway in turbulent flow to a catchment tank at the bottom end of the raceway. The material is recirculated over the raceway every two to three minutes for a period of two to six hours. The oxidation process can be used in conjunction with heating and vibration of the raceway to oxidize the particles. The oxidation process is particularly used in the separation of metals from ores in which after oxidation leaching agents including bromide and chlorine compounds are added to the mixture during the recirculation over the raceway to leach the metals in soluble salts from the particles. Ion exchange systems are used using known resins to extract the metals from the liquid after the recirculation system is complete.

Abstract: The invention relates to a method of preparing a dental amalgam that is devoid of harmful free mercury, to be used as a filler for dental cavities. In particular the invention relates to processes by which two separate compositions characterized as treated silver and silver-mercury compound are formed, which are then used in a mixture with mercury to form the dental amalgam.

Abstract: A system and method for recovering metal contaminants from soil, including a leaching subsystem and a metal recovery system.

Abstract: A process for recovering gold from a refractory auriferous ore containing sulfide sulfur. An aqueous slurry of refractory auriferous ore is subjected to pressure oxidation in an autoclave while the distribution of oxygen to the various compartments of the autoclave is controlled in order to achieve increased oxygen utilization.

Abstract: In a process for the recovery of silver by flotation from the residue from the wet extraction of zinc, the residue from the neutral wet extraction of zinc, the residue from the neutral wet extraction of zinc is recovered and is subsequently ground in an attritor and the residue which has been ground in an attritor is subjected to a flotation.

Abstract: A process suitable for the extraction or recovery of metal values from arsenic containing feeds and including the steps of: a) treating the feed with a nitric acid-containing leachant solution in order to dissolve the desired metals; b) adding a source of iron (III) to the leachant solution whereby to oxidise arsenic (III) in solution to arsenic (V); c) adding a neutralising agent to the leachant solution whereby to precipitate arsenic as arsenic (V); d) separating the arsenic (V) precipitate from the leachant solution; and e) recording metal values from the leachant solution.

Abstract: A method of producing a high-purity, ultra-fine powder of a first metal, particularly silver, by forming an alloy of the first metal with a second metal, such as aluminum subjecting the alloy to a leaching agent effective to leach out the second metal, leaving a porous first metal agglomerate; mixing the porous first metal agglomerate with a fresh batch of leaching agent; disintegrating the agglomerate and applying ultrasonic oscillations to the mixture to enhance the penetration of the leaching agent into the pores of the agglomerate; removing the leaching agent, leaving the first metal; and washing and drying the first metal.

Abstract: A biohydrometallurgical apparatus and method for extracting precious metals, including gold and silver, from oxidized ore by means of leaching with a neutral bisulfide solution instead of cyanide, thiourea, thiosulfate, or other conventional lixiviants is disclosed. In a preferred embodiment, a first process step of conventional bio-oxidation of ore particles is accomplished to free precious metals dispersed or occluded within the ore. A portion of the acidic, base-metal sulfate leach solution produced by bio-oxidation is introduced to an anaerobic reactor. In a heap leach embodiment of the process, the anaerobic reactor is a side-stream reactor. In an alternative slurry (e.g.,vat) leaching embodiment, the anaerobic process may occur on-line. A preferably non-toxic electron donor, such as acetate or methanol (which does not bind effectively to activated carbon), is added to the anaerobic reactor to enrich within it a mixed culture of sulfate-reducing bacteria.

Abstract: A method of recovering precious metal values from refractory sulfide ores is provided. The method includes the steps of separating clays and fines from a crushed refractory sulfide ore, forming a heap from the refractory sulfide ore, bioleaching the heap to thereby oxidize iron sulfides contained therein, and hydrometullurgically treating the bioleached ore to recover the precious metal values. If sufficient quantity of precious metal values are contained in the separated clays and fines, these materials can be further processed to recover the precious metal values contained therein.