Abstract: Gold and other noble metal recovery from an ore slurry is improved by operating at low pulp densities, below 35%, and solubilizing base metal present in the slurry by adding to the slurry, either prior to or during the leaching step, one or more solubilizing agents for the base metal.

Abstract: Ores containing copper, zinc, silver in the form of sulfides are treated by a solution of sulfurated sulfite ions and ammonium ions in order to remove most of the metals from the sulfide ores. This treatment renders the resulting gold bearing ores much more amenable to cyanide extraction. Dissolved metals are reclaimed by appropriate techniques, such as electrowinning or liquid-liquid extraction, and the solution of sulfurated sulfites and ammonia is recycled for further lixiviation of fresh ores.

Abstract: Provided is a method for treating refractory gold-bearing ores that have both sulfide material with which the gold is associated and from which the gold is difficult to separate and having organic carbonaceous material having an affinity for at least one of gold and a gold complex. The mineral material is pressure oxidized in the presence of a halogen-containing material in a manner to reduce the susceptibility of the organic carbonaceous material to capture and hold gold during the pressure oxidation. Also provided is a gold-bearing effluent product from the pressure oxidation process. The effluent product comprises gold which can be effectively recovered by carbon-in-leach cyanidation of the effluent product. In many cases, gold recovery according to the present invention is increased substantially over standard pressure oxidation techniques.

Abstract: Provided is a method for processing a gold-bearing sulfide ore which involves maintaining the ore in a substantially oxygen free environment, preferably beginning with comminution of the ore and ending when a desired final concentrate, enriched in sulfide minerals, is obtained by flotation. In one embodiment, nitrogen gas is used to substantially prevent contact between the ore and air during comminution of the ore and during flotation operations. It is believed that oxygen gas present in air detrimentally affects the recovery of sulfide minerals in a flotation concentrate through surface oxidation of sulfide mineral particles. The use of a gas such as nitrogen can significantly reduce the potential for such surface oxidation.

Abstract: An improved method for extracting a precious metal from mineral fines by heap leaching with dilute sulfuric acid which comprises agglomerating the mineral fines prior to formation into a heap with an agglomerating agent composition comprising sequential addition of a first polymer selected from the group consisting of anionic and nonionic water-soluble polymers and then a second cationic water-soluble polymer to the fines. Preferred first polymers are poly(acrylamide) and 70/30 mole percent poly(acrylamide/sodium acrylate), and preferred second polymers are poly(diallyldimethylammonium chloride), 90/10 mole percent poly(acrylamide/diallyldimethylammonium chloride) and 99/1 mole percent poly(diallyldimethylammonium chloride/vinyltrimethoxysilane).

Abstract: An aqueous phase oxidization process for the oxidization of any nonoxidized feed material using a mixture of a feed material, an oxidizing acid, such as nitric acid; oxygen gas, water and preferably a stabilizing acid, such as sulfuric acid. The mixture is pressurized in a reactor and maintained at a temperature no greater than about 210.degree. C. Sufficient oxygen gas is added to increase the pressure beyond the pressure resulting from any gases formed during the oxidation process and to ensure that a substantial portion of reduction products of nitric acid formed during oxidation of the feed are substantially reoxidized to nitric acid.

Abstract: The ore which contains gold and at least one of the metals silver, copper, nickel, zinc or iron is calcined at temperatures in the range from 500.degree. to 900.degree. C. with the addition of oxygen-containing gas, thereby producing a metal-oxide-containing solids mixture and a SO.sub.2 -containing exhaust gas. The SO.sub.2 containing exhaust gas is brought in contact with aqueous solution, thereby producing a sulfite-containing solution. The solids mixture from the calcination is cooled to temperatures in the range from 50.degree. to 300.degree. C. and is stirred up with the sulfite-containing solution. Metal oxides are dissolved, and a sulfate-containing solution os formed. In a first separating zone, the sulfate-containing solution is separated from the solids, and either the solids are supplied to a gold leaching or the sulfate-containing solution is subjected to a further treatment for the separation of nonferrous metals.

Abstract: The ore which contains gold and/or silver and as accompanying metal at least iron is calcined at temperatures in the range from 500.degree. to 900.degree. C. with the addition of oxygen-containing gas. There is obtained a metal-oxide-containing solids mixture and a SO.sub.2 -containing exhaust gas. The solids mixture from the calcination is cooled, the temperature being reduced by at least 50.degree. C. The cooled solids mixture is added to a fluidized-bed reactor, and SO.sub.2 -containing exhaust gas is introduced into the fluidized-bed reactor. In the reactor, metal sulfate is produced in the solids mixture, so that at least 10% of the sulfur content are bound in the exhaust gas. Solids mixture containing metal sulfate is withdrawn from the fluidized-bed reactor, is stirred up with an aqueous acid solution, thereby dissolving metal sulfate. The remaining solids are supplied to a recovery of gold and/or silver.

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 hydrometallurgical process for treating copper feed materials containing gold and/or silver by simultaneously leaching copper, gold and/or silver into an aqueous cyanide solution, recovering copper in metallic form by electrowinning and regenerating cyanide ions is provided, wherein high current efficiencies are achieved at high current densities and at low copper concentrations.

Abstract: A process for the percolation leaching of minerals from a mineral-beating ore comprises agglomerating the mineral-bearing ore with an agglomerating agent of a cationic block copolymer having a polymeric segment and a block containing an ammonium cation optionally with a block derived from an acrylamide monomer, forming the ore/agglomerating agent mixture into a heap, and leaching the heap by percolation with a leaching solution for subsequent recovery of the minerals at an acidic pH.

Abstract: Provided is a method for processing a gold-bearing sulfide ore which involves maintaining the ore in a substantially oxygen free environment, preferably beginning with comminution of the ore and ending when a desired final concentrate, enriched in sulfide minerals, is obtained by flotation. In one embodiment, nitrogen gas is used to substantially prevent contact between the ore and air during comminution of the ore and during flotation operations. It is believed that oxygen gas present in air detrimentally affects the recovery of sulfide minerals in a flotation concentrate through surface oxidation of sulfide mineral particles. The use of a gas such as nitrogen can significantly reduce the potential for such surface oxidation.

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 for producing crystallites comprising silica and antimony containing tin oxide. The quantity of antimony within the tin oxide can be reduced, thereby permitting production a powder which is absent a blue coloration.

Abstract: Agglomerating agent and method for use in heap leaching of mineral bearing ores. Cationic polymers alone or in combination with cement or lime are highly effective agglomerating agents in acidic or alkaline leaching operations. The cationic polymers are preferably graft copolymers, block copolymers or linear copolymers of acrylamide and diallyl dimethyl ammonium chloride.

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: An agglomerating agent for use in the heap leaching of mineral bearing ores is disclosed. The agglomerating agent is a polyvinyl alcohol of moderate to high molecular weight which is partially or fully hydrolyzed. The polyvinyl alcohol agglomerating agent can be used alone or in combination with cement or lime in acidic or alkaline heap leaching operations.

Abstract: A recovery method for base metal values (e.g. copper) from ore slurry or aqueous solution, comprising forming a solution of a metal complex (e.g. cyano-copper) having an affinity for adsorption sites on activated carbon, adsorbing the metal complex onto activated carbon, and stripping the adsorbed metal complex by forming a reaction product with said metal complex, the reaction product having no affinity for adsorption sites on activated carbon. A method for recovering base metals and noble metals separately from an ore containing both is also disclosed. The method is carried out in an apparatus comprising a leaching stage (17) and an adsorption stage (221) which may be combined, and an elution column (11). The method and apparatus also provide a mechanism for recovery of activated carbon and cyanide.

Abstract: A hydrometallurgical process is described for recovery of precious metals from ores refractory to treatment by lixiviating agents by crushing the ore to no finer than a nominal 1/4 inch size, treating the ore with about 100% to about 300% of the stoichiometric amount of nitric acid required to react with the ore, maintaining the reaction mixture until the reaction is substantially complete, placing the treated ore in a permeable ore bed, washing the permeable ore bed to remove nitric acid, placing the washed ore in a heap permeable ore bed and passing a lixiviate solution for precious metals through the bed and recovering the dissolved precious metal from the lixiviate solution. All NOx gases generated during the reaction of nitric acid with the ore are recovered for conversion into nitric acid which is recycled for treating ore.

Abstract: A hydrometallurgical process for treating copper ores or concentrates containing gold by simultaneously leaching both copper and gold into an aqueous cyanide solution, recovering copper and gold in metallic form by electrowinning or cementation and regenerating cyanide ions is provided.

Abstract: The present invention relates to a process for roasting gold containing ore in which a flash furnace means is provided, in particular a gas suspension furnace for roasting the ore. Hot gas and the gold containing ore to be roasted are supplied to the furnace means, wherein the hot gas roasts the ore within the furnace means at temperatures between about 500.degree. C. and 700.degree. C. while the ore is suspended in the hot gas, after which the roasted ore is discharged from the furnace means along with the hot gas. In the apparatus of the present the ore to be calcined may optionally be preheated, prior to the ore entering the furnace means, by suspending the fresh ore in hot gas.

Abstract: A variety of processes for recovering gold from gold ore are disclosed. Briefly, the methods include culturing at least one microorganism species capable of producing cyanide ion under conditions wherein the microorganism produces cyanide ion, thus forming a cyanide ion-containing culture; contacting the cyanide ion-containing culture with gold ore, causing production of gold ion-cyanide ion complexes and biosorption of said complexes to said cultures; and recovering gold from the culture. The invention may be practiced with a variety of microorganisms, including Chromobacterium violaceum and Chlorella vulgaris.

Abstract: Calcium carbonate scale deposits, occurring in gold and silver mining involving the cyanidation process which utilizes heap and vat leaching, and carbon-in-pulp, carbon-in-leach, particularly activated carbon separation columns; said scale deposits forming on the carbon surfaces and in the emitters and sprinklers of the heap leaching system, are controlled using polyether polyamino methylene phosphonates, which provide effective inhibition despite the severe conditions encountered in these systems, including very high pH's.

Abstract: Process for recovering cyanide values from a mill tailings stream remaining after gold and silver have been leached from an ore, by treating the tailings stream containing both ore insolubles and remaining cyanide leachant, without a preliminary filtration, to acidification with an acid to a pH of at least 4, stripping the cyanide values therefrom with a stripping gas in a stripping column such as a baffle plate column wherein the average residence time of the column is sufficiently low that the pH of the stream does not rise above about 4 and the ore insolubles do not plug the column, introducing the stripping gas and stripped cyanide values into an absorbing column containing an alkaline liquor to absorb the cyanide values, recovering the absorbed cyanide values, and removing a stripped tailings stream reduced in cyanide values.

Abstract: A process for recovering at least one precious metal from an ore containing carbonaceous material is disclosed. The process involves the use of certain plant derived ortho-quinone containing components, in particular, certain lignin and/or tannin derived components containing ortho-quinone functionality.Preferred compositions comprise at least one ligno sulfonate component containing ortho-quinone functionality. In the process, the use of at least one additional oxidant capable of maintaining the ortho-quinone containing functionality in the desired oxidation state provides for integrated process synergy.

Abstract: A process for recovering at least one precious metal from an ore containing metal sulfide material is disclosed. The process involves the use of promoting amounts of certain plant derived ortho-quinone containing components, in particular, certain lignin and/or tannin derived components containing ortho-quinone functionality. Preferred compositions comprise at least one ligno sulfonate component containing ortho-quinone functionality. In the process, the use of at least one additional oxidant capable of maintaining the ortho-quinone containing functionality in the desired oxidation state provides for integrated process synergy.

Abstract: A process is disclosed for the leaching of gold and silver from ores and ore concentrates through intimate contact of the ore or ore concentrate with an aqueous leach solution containing cyanide. The leach solution has a pH of 8 to 13. The leaching process takes place in the presence of an oxygen-releasing peroxo compound. The separation of the formed cyano complexes of gold and silver takes place in a known manner. During leaching, at least one peroxoborate compound is present, in an effective quantity, as the peroxo compound. The peroxoborate is preferably a sodium or calcium peroxoborate. Compared to previously known leaching techniques in the presence of hydrogen peroxide or calcium peroxide, the leaching process according to the present invention provides a higher and/or faster precious metal yield and/or minimizes the consumption of cyanide and/or oxidizing agent.

Abstract: Increased efficiency of extraction of silver and gold from ore materials thereof containing active carbonaceous material is obtained by conducting the extraction in two stages. In a first stage a portion of the silver and of the gold when present is extracted in a cyanide leach solution. The leached solids residue is contacted with activated carbon so that the silver and the gold when present are adsorbed on the activated carbon at elevated temperature (most preferably at about 35.degree. C. to about 100.degree. C.). In a modification, a slurry of the ore material is treated with cyanide and the precious metal adsorbed directly from the cyanided slurry with activated carbon at elevated temperature up to about 70.degree. C.

Abstract: The invention relates to the extraction of metal values from metal bearing ores. More specifically, the invention comprises, in a process 10 for extracting metal values from metal bearing ores, a method of enhancing metal value recovery from the ore. The method comprises introducing, upstream of a metal recovery section 26, a gaseous agent by means of arrangements 30. The gaseous agent is capable of promoting recovery of metal values from the ore. The gaseous agent introduction is into at least one of the pipelines 20, 24, 28 conveying ore slurry or process water for use in slurry ore or for slurry make-up.

Abstract: This invention relates to the extraction of metal values from metal bearing ores. More particularly, in a process for recovering metal values from metal bearing ore, the invention provides the step of enhancing metal value recovery by introducing into the thickener overflow water 32, a gaseous agent capable of promoting recovery of the metal values from the ore. The gaseous agent may be oxygen or oxygen enriched gas, and can be injected by means of injection means 50.

Abstract: In a process for the preparation and the isolation of p-hydroxybenzonitrile (HBN), in which a p-halogenated phenol is reacted with cuprous cyanide in a suitable solvent, the reaction mixture obtained after the reaction of the p-halogenated phenol with cuprous cyanide has been substantially completed is contacted with an aqueous solution of a bromide salt and, optionally, an organic diluent, the aqueous and organic phases are separated, HBN is distilled out from the organic phase, an alkali metal cyanide is added to the aqueous phase and CuCN is filtered off from the resulting aqueous phase.

Abstract: A variety of processes for recovering gold from gold ore are disclosed. Briefly, the methods include culturing at least one microorganism species capable of producing cyanide ion under conditions wherein the microorganism produces cyanide ion, thus forming a cyanide ion-containing culture; contacting the cyanide ion-containing culture with gold ore, causing production of gold ion-cyanide ion complexes and biosorption of said complexes to said cultures; and recovering gold from the culture. The invention may be practiced with a variety of microorganisms, including Chromobacterium violaceum and Chlorella vuloaris.

Abstract: This invention relates to the extraction of metal values from metal bearing ores. More specifically, according to the invention, in a process for extracting metal values from metal bearing ores, there is provided a method of enhancing metal value recovery from the ore. The method comprises introducing, upstream of a metal recovery section 26, a gaseous or liquid agent capable of promoting recovery of the metal values from the ore, into the gland service water from at least one of the pumps 30. The introduction of the gaseous or liquid agent is by means of an arrangement 35. The agent may be oxygen.

Abstract: A process for recovering at least one precious metal from an ore containing carbonaceous material is disclosed. The process involves the use of promoting amounts of certain metal redox couples and/or metal components, in particular, certain metal complexes with ligands.Preferred metal compositions comprise at least one of (1) redox cyclable vanadium (5+) ligand complex, (2) redox cyclable iron (3+) ligand complex, and (3) redox cyclable manganese (3+) ligand complex. In the process, the use of at least one regenerable component capable of maintaining the complexed metal in the desired oxidation state provides for integrated process synergy.

Abstract: A process for recovering at least one precious metal from an ore containing carbonaceous material is disclosed. The process involves the use of promoting amounts of certain metal redox couples and/or metal components, in particular, certain metal complexes with ligands.Preferred metal compositions comprise at least one of (1) redox cyclable vanadium (5+) ligand complex, (2) redox cyclable iron (3+) ligand complex, and (3) redox cyclable manganese (3+) ligand complex. In the process, the use of at least one regenerable component capable of maintaining the complexed metal in the desired oxidation state provides for integrated process synergy.

Abstract: A process is described for leaching gold and/or silver from ores or ore concentrates using an aqueous alkaline cyanide solution with addition of hydrogen peroxide. The addition of the aqueous H.sub.2 O.sub.2 solution is regulated and controlled through the concentration of the oxygen dissolved in the leaching solution, the leaching solution containing from 2 to 20 mg O.sub.2 and preferably from 7 to 13 mg O.sub.2 per liter. 0.5 to 5% by weight H.sub.2 O.sub.2 solutions are preferably added. The process is applicable both to leaching by agitation and to heap leaching, the addition of H.sub.2 O.sub.2 being regulated and controlled through measurement of the O.sub.2 concentration in the leaching solution and can also involve measurement in a measuring stream. Despite low consumptions of H.sub.2 O.sub.2 and NaCN, the gold yield is even increased in some cases and the leaching time shortened.

Abstract: A method for treating cyanide-contaminated water in order to remove dissolved (e.g. free) cyanide (HCN and/or CN.sup.-) therefrom. Cyanide-contaminated water is a significant problem in the gold processing industry wherein cyanide compounds are used to remove gold from ore. The remaining cyanide solution after gold extraction is treated to reduce free cyanide levels therein by combining the solution with a crystalline waste by-product of the metal galvanizing industry having the following formula: (Fe.multidot.Zn)SO.sub.4 .multidot.7H.sub.2 O. This material preferably has a zinc content of about 1-14% by weight, and is added to the water in an amount equal to about 1-5 pounds per ton of ore being processed. As a result, a stable, solid, non-toxic complex is produced from the toxic free cyanide materials. This is accomplished without the generation of harmful acids, heavy metals, excessive iron levels or other undesired by-products.

Abstract: A method of recovering precious metals from a silver bearing ore containing polybasite, pearcite, pyrargyrite, tetrahedrite or argentite by mixing the ore with an alkali metal or alkaline earth metal peroxide in slurry or solid, leaching the ore with a cyanide solution, and recovering the precious metals from the cyanide solution.

Abstract: A method for roasting sulphide ores or ore concentrates containing precious metals is practiced in a furnace, typically in a fluidized bed. The ore and a sulphur-binding lime-containing material are supplied to a roasting furnace in which the ore is roasted with the emission of heat and sulphur dioxide. The lime-containing material--such as calcium hydroxide--is mixed into the cooling water for the roasting furnace and sprayed into the furnace as a lime-containing aqueous slurry. Roasting occurs at about 600-850.degree. C. (e.g. 650-750.degree. C.).Roasted material is discharged from the furnace and acted upon to recover gold, silver and copper metal.

Abstract: A process for recycling hydrogen cyanide from a cyanide-containing slurry is provided. The process includes the steps of adjusting the pH of a cyanide-containing slurry, volatilizing HCN contained in the pH adjusted slurry and contacting the volatilized HCN with a precious metals-containing slurry to recover precious metals therefrom. Alternatively, the HCN can be contacted with reclaim, or decant, water to recover cyanide, thereby conserving resources.

Abstract: A process for leaching gold and silver from ores and ore concentrates is disclosed using a cyanide leaching solution and hydrogen peroxide and maintaining an oxygen concentration of 2 to 20 Mg of O.sub.2 /liter. In the invention, leaching takes place in the presence of decomposition catalysts and preferably the formed cyano-complexes are separated during leaching from the leach solution. Decomposition catalysts are manganese compounds, present as 0.01 to 1 mg computed as Mn/liter of barren solution, or 1 to 50 mg computed as Mn per kg of ore slurry, or they are inorganic or organic polymers or carbon. Activated charcoal is preferred and simultaneously adsorbing cyano-complexes of precious metals. The process offers lowered consumption of H.sub.2 O.sub.2 and possibly cyanide and maximum gold yield in a shortened leaching time.

Abstract: A process for biooxidation of sulfides in a heap of mineral ores by freeing precious metals dispersed or occluded within said ores as pyritic or arsenopyritic sulfides and the like; the process comprises forming particulates from ore particles with an inoculate comprising bacteria capable of attacking, by biooxidation, sulfides and/or elemental sulfur in said ore particles; from these particulates a heap is constructed; and the biooxidation takes place in such heap by adding to or dispersing within the heap a leaching solution, circulating the leaching solution within the heap and recovering the precious metal values from the heap; recovery may be accomplished with a cyanide, thiourea, or a thiosulfate lixiviant.

Abstract: A method and apparatus are described for recovering gold from aqueous slurries of refractory gold ores containing sulfidic and/or carbonaceous matter. The method entails pretreating an ore slurry with chlorine in a multi-compartment autoclave operated at an elevated pressure. The chlorine used in this pressure chlorination pretreatment can be in either the gaseous or liquid state. Following the removal of residual chlorine from the pretreated ore slurry, said slurry is transferred to a conventional cyanide leach/carbon adsorption circuit to recover the gold values.

Abstract: In gold and/or silver cyanide leaching-adsorption processes employing solid adsorbents such as activated charcoal, the overall efficiency in the recovery of gold and/or silver from ores or the like is greatly increased by contacting the cyanide slurry containing the gold and/or silver, with oxygen gas instead of normal air. A generally pure oxygen gas can be bubbled into a vessel containing the slurry, and a cover (e.g. a floating cover) may be provided on the vessel to reduce the oxygen transfer out of the solution and to facilitate pressurization of the system with an oxygen atmosphere. The procedures of the invention are applicable to carbon-in-pulp (CIP), and carbon-in-leach (CIL) processes and related processes using resins. Deaeration of the ore slurry can be practiced prior to the introduction of the oxygen.

Abstract: A method for improving the yield of gold and silver from a Merrill-Crowe recovery process where the presence of copper effects yield. The method involves the addition of a substoichiometric amount of ethylenediaminetetraacetic acid in combination with a phosphonate and polyacrylic copolymer scale control agent. The method also reduces zinc consumption and controls scaling in the stripping circuit.

Abstract: Agglomerating agent and method for use in heap leaching of mineral bearing ores. A moderate to high molecular weight anionic polymer preferably in combination with lime provides a highly effective agglomerating agent. The anionic polymer is preferably a copolymer of acrylamide and acrylic acid. The polymer preferably has a molecular weight of from about 1 to 8 million or higher.

Abstract: Agglomerating agent and method for use in heap leaching of mineral bearing ores. A moderate to high molecular weight anionic polymer in combination with lime provides a highly effective agglomerating agent. The anionic polymer is preferably a copolymer of acrylamide and acrylic acid. The polymer preferably has a molecular weight of from about 1 to 8 million or higher.

Abstract: An improved process for stripping gold cyanide from activated carbon is disclosed. The process involves contact of gold-laden activated carbon with a strong base at ambient temperatures followed by elution with an aqueous solution containing an organic solvent, preferably aqueous acetonitrile or methanol. Gold cyanide is separated from the aqueous/organic solution by ion-exchange technology, preferably using a weak base ion-exchange resin, followed by elution with a strong base.

Abstract: Mill tailings containing cyanide species can be treated with carbon dioxide in order to drive-off and/or recover the cyanide content of said tailings.