Abstract: A method for recovering a precious metal from a host material, comprises the steps of subjecting the host material to an oxidative pressure leach process, in the presence of a halide ion constituent which is reactive with the precious metal, and at a temperature sufficient to cause at least a portion of the precious metal to be extracted by a leach solution; and recovering the precious metal from the leach solution.

Abstract: A method for preparing ultra-pure silver from a crude silver mixture containing metallic and/or non-metallic impurities, said method comprising; dissolving the crude silver mixture in nitric acid to form a crude silver nitrate solution; adding a first selective reducing agent to the crude silver nitrate solution to precipitate a silver/contaminant matrix and form a partially purified silver nitrate solution; separating the partially purified silver nitrate solution from the precipitated silver/contaminant matrix; adding a second selective reducing agent to the partially purified silver nitrate solution to precipitate silver powder; and isolating the silver powder.

Abstract: A method for preparing ultra-pure silver from a crude silver halide matrix containing metallic and/or non-metallic impurities, said method comprising; roasting the crude silver halide matrix to substantially remove carbonaceous material; treating the roasted crude silver halide matrix with ammonium hydroxide to dissolve the silver halides and form an ammonium hydroxide reaction mixture; adding an initial reducing agent to the ammonium hydroxide reaction mixture to precipitate a crude silver powder mixture; separating the crude silver powder mixture from the ammonium hydroxide reaction mixture dissolving the crude silver powder mixture in nitric acid to form a crude silver nitrate solution; adding a first selective reducing agent to the crude silver nitrate solution to precipitate a silver/contaminant matrix and form a partially purified silver nitrate solution; separating the partially purified silver nitrate solution from the precipitated silver/contaminant matrix; adding a second selective reducing

Abstract: A process is provided for the leaching of copper from chalcopyrite using ferric sulfate in which acceptable rates of leaching are achieved by controlling the surface potential of the chalcopyrite to an empirically determined “window” within the broad range of 350 to 450 mV. The most effective process conditions involve the selection of the said surface potential; the leach temperature; the pH of the leach solution; and the fineness of the grind of the chalcopyrite. The invention may be applied to both tank leaching and heap leaching processes.

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: In an acid leach copper extraction circuit for leaching copper values from copper ores using a water-immiscible organic solvent solution containing a copper extractant and an acid strip solution, the improvement wherein the stripped organic solvent solution is contacted with copper-free fresh aqueous acid to remove additional copper values therefrom, and then the resulting super stripped organic and the copper-containing aqueous acid are sent to the copper extraction circuit.

Abstract: A method for recovering gold from gold-loaded fine carbon residue from a coarse carbon gold recovery process is disclosed. The gold-loaded fine carbon residue is mixed with activated coarse carbon and an aqueous solution of a transfer reagent to form a slurry. In the slurry the reagent promotes transfer of gold from the fine carbon to the coarse carbon. After allowing time for the transfer, gold-loaded coarse carbon is separated from the slurry. Gold can then be recovered from the separated coarse carbon, for example by cyanide leaching followed by electrowinning. More gold can be recovered by adding further coarse carbon and repeating the transfer of gold to that coarse carbon. In one example 66% of gold was transferred from the fine carbon to the coarse carbon in one transfer cycle. About 89% and 96% of gold can be recovered after respectively second and third transfer cycles.

Abstract: A method is provided for flotation of refractory auriferous sulfide using an oxygen-deficient flotation gas. The method is particularly suited for non-selective flotation of different iron-containing sulfide mineral species. Comminution prior to flotation may be performed in an oxygen-deficient environment.

Abstract: A method is disclosed for recovering a metal from a metal containing material by autoclaving with an autoclave which includes an agitator that includes a first inlet for a recycled oxygen-containing gas, a second inlet for a fresh oxygen-containing gas, an impeller having a plurality of outlets to recirculate or introduce the oxygen-containing gases into the slurry and a set of mixing blades located below the outlets to radially disperse gas bubbles substantially uniformly throughout the slurry. The outlets for the gas can be located in an intermediate set of blades for thorough dispersion of the gas bubbles in the slurry.

Abstract: A process for the extraction of metal from an ore or concentrate which contains nickel and/or cobalt values and other metals, comprises subjecting the ore or concentrate to acid leaching under pressure at pH≦2 to obtain a liquor containing nickel and/or cobalt values, subjecting the liquor to a first precipitation stage at pH of about 5 to 6 to produce a solid containing non nickel and non cobalt metals and a resultant solution containing the nickel and/or cobalt values and subjecting the resultant solution to a second precipitation stage at a pH of about 7 to 8 to produce a solid containing nickel and/or cobalt.

Abstract: Disclosed is a process for leaching copper from copper sulfide using bacteria, which ensures that the rate of leaching of copper increases to reduce the leaching time period and that the rate of leaching of primary copper sulfide contained in ores is increased. The process comprises using an acid leaching solution that includes both or any one of iron oxidizing bacteria and sulfur oxidizing bacteria in a concentration of 106 microbes/mL, the acid leaching solution having a redox potential of from 550 to 750 mV and 5 g/L or more of iron, the ratio of trivalent iron ions to bivalent iron ions (Fe3+/Fe2+) in the acid leaching solution being 50 or more.

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 process for oxidation of ferrous ions in solution, and more particularly a process for improved base metal and/or uranium leaching from ores, concentrates or tailings using ferric ion as an oxidizing agent. A reaction vessel (10) holds a ferrous ion-containing solution, for example, a copper sulphide leach slurry or concentrate. An agitator (12) may be provided to promote leaching of the base metal into solution. Some of the ferrous ion-containing solution is drawn off from the reaction vessel (10) and pumped through an in-line mixer (14) via a feed pump (16). Oxygen is injected into the reactor (14) to facilitate oxidation of the ferrous sulphate to form ferric sulphate. The ferric ion-containing solution is then recirculated back to the reaction vessel (10) where the ferric ions are reused in the dissolution of copper sulphide into soluble copper sulphate.

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: According to the process, a heap preferably having dimensions of at least 2.5 m high and 5 m wide is constructed with chalcopyrite bearing ore. The constructed heap includes exposed sulfide mineral particles at least 25 weight % of which are chalcopyrite. The concentration of the exposed sulfide mineral particles in the heap is such that the heap includes at least 10 Kg of exposed sulfide sulfur per tonne of solids in the heap. Furthermore, at least 50% of the total copper in the heap is in the form of chalcopyrite. A substantial portion of the heap is then heated to a temperature of at least 50.degree. C. The heap is inoculated, with a culture including at least one strain of thermophilic microorganisms capable of bioleaching sulfide minerals at a temperature above 50.degree. C. A process leach solution that includes sulfuric acid and ferric iron is applied to the heap.

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 plurality of substrates, such as coarse ore particles, lava rock, gravel or rock containing a small amount of mineral carbonate as a source of CO.sub.2 for the biooxidizing bacteria. After the sulfide minerals are coated or spread onto the plurality of substrates, a heap is formed with the coated substrates or the coated substrates are placed within a tank. The sulfide minerals on the surface of the plurality of coated substrates 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, pyrite or sphalorite.

Abstract: A method for improving bacteria and reagent actions on mineral-bearing particles. In the heap leaching process, the method also increases percolation of the leach solution through the heaped ore without the use of high concentrations of cement, high concentrations of high molecular weight polymers, or high concentration of any other binding agents. The method is accomplished by a process comprising the applying of solutions of varying combinations of bacteria, bacterial nutrients, or leaching reagents, together with surface acting agents onto the ore particles before the ore is formed into a heap. The reagents are applied by spray or foggers or foam into the ore as the ore is mined, transported out of the mine, crushed, or transferred to the heap, and before it is formed into the heap.

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: Methods for decontaminating toxic waste, particularly solid carrier materials, such as soil contaminated with a toxin, or solid mixed wastes are more efficiently decontaminated with solvated electrons by first extracting the toxin from the carrier with a nitrogenous base at elevated temperatures, followed by a temperature reduction before initiating chemical reduction of the toxin with solvated electrons. Pre-extraction of the toxin at elevated temperatures followed by temperature reduction minimizes competing side reactions, improves selectivity of solvated electrons for the toxin and improves the economics of the process with more efficient metal utilization. The process can be performed without separation of the toxin from the extraction vessel holding the solid carrier material. Alternatively, elevated temperatures can be used to perform one or more extractions of toxin with nitrogenous base followed by reduction with solvated electrons by performing the reaction in a separate reactor.

Abstract: A method for removing a heavy metal from sludge, including the step of putting the sludge into contact with a treating liquid to dissolve the heavy metal contained in the sludge into the treating liquid. The treating liquid is formed of either A or B, where (A) is an aqueous solution of phosphoric acid, and (B) is an aqueous solution of phosphoric acid containing at least one of B1 and B2, where (B1) is at least one acid other than phosphoric acid, and (B2) is at least one oxidant. The concentration of the phosphoric acid in the treating liquid is 3% by weight or more. Alternatively, the sludge is put into contact with the treating liquid at a temperature of 40.degree. C. or higher.

Abstract: The invention relates to a method of recovering precious metals from oxidic or refractory or semi-refractory ore material containing precious metal. This recovery of precious metal takes place with optimal comminution work and with more efficient and more reliable leaching also of non-oxidic ore material in such a way that the ore material is subjected to material bed comminution in the grinding gap between two rollers which are pressed against one another under high pressure and revolve in opposite directions and afterwards the comminuted ore material is preferably leached using a stirring movement in a container.

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: 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: A process for the extraction of precious metals from a copper sulphide ore or concentrate, by treating a leach residue of the ore or concentrate, includes the steps of removing elemental sulphur from the leach residue to obtain a low sulphur residue and subjecting the low sulphur residue to an oxidative leach at elevated temperature and pressure to oxidize sulphur and precious metal compounds present in the low sulphur residue to produce a residue for the extraction of the precious metals therefrom.

Abstract: The present invention is directed to a process for recovering copper from a copper-containing material by pressure oxidation followed by solvent extraction and electrowinning. The copper-containing solution formed by pressure oxidation is diluted before solvent extraction and the raffinate solution from solvent extraction is neutralized to reduce the acid levels in the raffinate solution.

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: 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: 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: 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: 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.

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 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: There is provided a novel hydrometallurgical process for the extraction of copper from sulphidic concentrates involving an oxidizing pressure leach using dilute sulphuric acid and a carbonaceous additive. The leaching step is carried out preferably at temperatures above the melting point of sulphur but below about 200.degree. C.

Abstract: The quaternary Zintl material (Et.sub.4 N).sub.4 ?Au(Ag.sub.1-x Au.sub.x).sub.2 Sn.sub.2 Te.sub.9 ! that contains 1-D semiconducting chains composed of four metallic elements is prepared by treating ethylenediamine extracts of a pentanary K--Au--Ag--Sn--Te alloy with Et.sub.4 NI.

Abstract: The present invention is directed to a process for recovering copper from a copper-containing material by pressure oxidation followed by solvent extraction and electrowinning. The copper-containing solution formed by pressure oxidation is diluted before solvent extraction and the raffinate solution from solvent extraction is neutralized to reduce the acid levels in the raffinate solution.

Abstract: This invention is directed to a process for making copper metal powder from copper-bearing material, comprising: (A) contacting said copper-bearing material with an effective mount of at least one aqueous leaching solution to dissolve copper ions in said leaching solution and form a copper-rich aqueous leaching solution; (B) contacting said copper-rich aqueous leaching solution with an effective amount of at least one water-insoluble extractant to transfer copper ions from said copper-rich aqueous leaching solution to said extractant to form a copper-rich extractant and a copper-depleted aqueous leaching solution; (C) separating said copper-rich extractant from said copper-depleted aqueous leaching solution; (D) contacting said copper-rich extractant with an effective amount of at least one aqueous stripping solution to transfer copper ions from said extractant to said stripping solution to form a copper-rich stripping solution and a copper-depleted extractant; (E) separating said copper-rich stripping soluti

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: Corrosion inhibiting composition include the use of certain plant derived catechol complexes in aqueous based compositions, such as process water, and other aqueous and non-aqueous solvent based coating compositions. The compositions have corrosion inhibiting and/or biocide activity. The compositions find particular usefulness as coatings, including paints, on iron and aluminum metal surfaces.

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: 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, nickel and cobalt. During pressure oxidation the metal may be precipitated as an insoluble basic salt, such as basic copper sulphate, or substantially completely solubilized and precipitated later as the basic metal salt.

Abstract: The invention relates to a process for leaching nickel and copper from nickel-copper matte formed in pyrometallurgical nickel production by means of a multi-stage process. It is essential of the invention that the leaching of nickel takes place in at least two stages in conditions where free sulfuric acid is essentially absent, and that in these stages, the leaching of the nickel content of the matte is mainly carried out with copper as the oxidizer.

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 process for leaching gold, silver, platinum and palladium wherein an aqueous leaching solution containing bromine and bromide ion contacts a precious metal source to produce an aqueous leachate. A precursor composition for producing an aqueous leaching solution for leaching gold, silver, platinum and palladium. A process for electrogenerating bromine and a process for leaching gold, silver, platinum and palladium wherein bromine is electrogenerated and contacts a precious metal source to produce an aqueous leachate. A process for leaching gold, silver, platinum and palladium wherein bromine is electrogenerated from a solution containing chloride ions and bromide ions.

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: In the production of a 124-type or 123-type superconductor by a sol-gel method using alkoxides of respective metals, the use of a compound wherein a secbutoxy group and a hydroxy group are coordinated with a copper atom gives a superconductor composed of flat particles having a broad C plane. The dimensional ratio defined by l/d is at least 6.7 in the case of the 124-type or is at least 8.4 in the case of the 123-type. It shows a superconducting property at a liquid nitrogen temperature. This superconductor shows a higher critical current density than one obtained by a sintering method.

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 H2SO4. The metals which can be extracted by the process comprises copper as well as non-cuprous metals such as zinc, nickel and cobalt. During pressure oxidation the metal may be precipitated as an insoluble basic salt, such as basic copper sulphate, or substantially completely solubilized and precipitated later as the basic metal salt.

Abstract: Disclosed is a process for leaching low sulphur materials for recovery of metals contained in them. The process includes leaching a first low sulphur material containing metal values with a leaching agent produced by bacterial oxidation of a second material by bacterial action thereby liberating metal values from the first material by a substantially indirect bioleaching process.