Abstract: A process for the oxidative leaching of sulphide mineral species, the method characterized by the method steps of: leaching a slurry containing the mineral species in one or more reaction vessels; circulating a stream of leach liquor to a flash cooler; flashing the liquor in the flash cooler at a pressure less than atmospheric pressure so as to dissipate heat; and recirculating the liquor to the or each reaction vessel.

Abstract: A method is provided for recovering a catalytic element from a fuel cell membrane electrode assembly. The method includes grinding the membrane electrode assembly into a powder, extracting the catalytic element by forming a slurry comprising the powder and an acid leachate adapted to dissolve the catalytic element into a soluble salt, and separating the slurry into a depleted powder and a supernatant containing the catalytic element salt. The depleted powder is washed to remove any catalytic element salt retained within pores in the depleted powder and the catalytic element is purified from the salt.

Abstract: Processes are provided for recovering precious metals from refractory materials using thiosulfate lixiviants. The processes can employ lixiviants that include at most only small amounts of copper and/or ammonia and operate at a relatively low pH, reduction of polythionates, inert atmospheres to control polythionate production, and electrolytic solutions which provide relatively high rates of precious metal recovery.

Abstract: In a method for leaching gold from copper sulfides, the sulfide ores are first subjected to leaching of copper, thereby producing a leaching residue having 7.9% or less of the copper content. This leaching residue is mixed with a leach liquor, which contains the chloride ion and ferric ion and has 1.9 or less of pH. Gold and copper can be effectively leached from the copper sulfide ores. Ordinarily used oxidizing reagents such as hydrogen peroxide or nitric acid are not used. The gold, copper and iron can, therefore, be leached in a single process and by using an identical leaching liquor. The rate of gold leaching reaction can be enhanced by the co-presence of either copper or bromide ion or both together with the chloride and iron ion.

Abstract: The present invention is directed to a precious metal recovery process in which basic ferric sulphates and/or jarosites are controlled by a number of mechanisms, including control of the oxidation reaction conditions in the first autoclave compartment, hot curing of the autoclave discharge slurry, and/or contacting of the autoclave feed slurry with the hot cured discharge liquid.

Abstract: A method for recovering precious metals such as gold and silver from aqueous solution as solid is described The method includes mixing an aqueous solution (e.g, thiosulfate or thiocyanate lixiviant) containing precious metals with ferrous ions in the presence of an effective amount of hydroxide ions. The precious metal ions are reduced and co-precipitate with iron hydroxides and/or hydrated iron oxides The co-precipitate is collected and purified. De-oxygenation of the reaction solution is optional. The recover/method is fast, complete and clean.

Abstract: The invention provides a recycling step in an oxidative pressure leaching process for recovery of metals using halide ions, in which a portion of the leached solids are recycled back to the feed to the autoclave, to allow two or more passes through the high temperature leaching step.

Abstract: The membrane electrode assemblies of fuel cells are recycled to recover the catalyst precious metals from the assemblies. The assemblies are cryogenically embrittled and pulverized to form a powder. The pulverized assemblies are then mixed with a surfactant to form a paste which is contacted with an acid solution to leach precious metals from the pulverized membranes.

Abstract: A method is provided for recovering a catalytic element from a fuel cell membrane electrode assembly. The method includes grinding the membrane electrode assembly into a powder, extracting the catalytic element by forming a slurry comprising the powder and an acid leachate adapted to dissolve the catalytic element into a soluble salt, and separating the slurry into a depleted powder and a supernatant containing the catalytic element salt. The depleted powder is washed to remove any catalytic element salt retained within pores in the depleted powder and the catalytic element is purified from the salt.

Abstract: The present invention relates to an improved method for the recovery of metal values, in particular copper and gold, from a metal value-bearing material containing arsenic and/or antimony and a source of sulphate ions, by means of a high temperature pressure oxidation process followed by cyanidation of the resultant high temperature pressure oxidation residue.

Abstract: Mineral materials comprising copper and precious metal are subjected to an acidic leach of the copper followed by an acidic thiocyanate leach of the precious metal.

Abstract: An improved process and composition for the extraction of metal from a metal-laden ore, soil or rock is provided. A liquid, three-component aqueous lixiviant comprises water, an alkali metal salt and a low pH acidic composition. A four-component aqueous lixiviant comprises water, a low pH acidic composition, an alkali metal salt and an acid having a pH value less than 2. Both lixiviant compositions are efficient for extracting metal into a pregnant liquid solution. The pregnant solution is treated by known conventional means, such as filtration, centrifuging or electrolysis to remove the extracted metals. The three-component and four-component aqueous lixiviants of the present invention are non-toxic, meaning, not an irritant or deleterious to humans or the environment and perform, as well as, or better than known toxic cyanide lixiviants.

Abstract: The copper sulfide ore is leached in the halide bath without using a special oxidant but with the use of only air. The copper and gold in the copper sulfide ore can be leached at high leaching ratio. The treating steps are as follows. (1) Copper leaching process (CL). The raw material is charged into the first acidic aqueous solution, which contains cupric chloride, ferric chloride, 7 g/L of hydrochloric acid, and sodium chloride. The post-leach liquor contains copper in cuprous state ions and copper in cupric state ions. (2) Solid-Liquid separation step. The resultant solid and liquid of CL step are separated. (3) Air oxidation step (OX). Air is blown into the post solid-liquid separation liquor. The copper in cuprous state ions are oxidized to the copper in cupric state ions. The iron leached in the step (1) is oxidized. Simultaneously, the impurities leached in the step (2) are precipitated. (4) Copper extracting step (CEX).

Abstract: A process of leaching gold comprising the steps of: a) leaching copper from copper sulfide ore material that contains gold or contains silicate ore containing gold until the copper grade is reduced to 7.9 wt % or less; b) mixing the resulting material having a copper grade of 7.9 wt % or less with a gold leaching solution selected from the group consisting of a first solution containing chloride ions and ferric ions, and a second solution containing chloride ions and iron ions, the iron ions having been oxidized to trivalent ferric ions by air bubbled into the second solution; c) adjusting the pH of the gold leaching solution to 1.9 or less with stirring to leach at least gold in the material into the gold leaching solution by the oxidative activity of the ferric ions contained in the gold leaching solution, wherein the concentration of gold is reduced by selectively removing gold from part or all of the gold leaching solution during gold leaching.

Abstract: Precious metal recovery by thiosulfate leaching where thiosulfate lixiviant is generated in situ employing elemental sulfur generated from partial oxidation of sulfidic precious metal-bearing feed and/or employing reactants from processing effluent.

Abstract: Processes are provided for recovering precious metals from refractory materials using thiosulfate lixiviants. The processes can employ lixiviants that include at most only small amounts of copper and/or ammonia and operate at a relatively low pH, reduction of polythionates, inert atmospheres to control polythionate production, and electrolytic solutions which provide relatively high rates of precious metal recovery.

Abstract: For removal of precious metal from thiocyanate leach solution, precious metal is transferred from precious metal-thiocyanate complex to precious metal-cyanide complex. Preparation of thiocyanate leach solution includes dissolving cyanide in an aqueous liquid and converting the cyanide to dissolved thiocyanate.

Abstract: The present invention relates to the use of monodisperse, macroporous chelating resins in the recovery of metals in hydrometallurgical processes, in particular in resin-in-pulp processes.

Abstract: The invention relates to a method for the recovery of metals, in particular copper, from a copper-bearing raw material, whereby the material is leached into a chloride-containing solution. The leaching of the raw material is performed oxidatively and at a sufficiently high redox potential that the copper in the copper chloride solution from leaching is mainly divalent. The chloride solution obtained, which contains copper and potentially other valuable metals, is fed to liquid-liquid extraction. In the extraction the copper is first transferred to the organic phase with extraction and then to a sulphate solution in stripping, which is fed to copper electrowinning.

Abstract: Processes are provided for recovering precious metals from refractory materials using thiosulfate lixiviants. The processes can employ heap leaching or lixiviants that include one or more blinding agents.

Abstract: A process of recovering platinum group metals (PGMs) from a pregnant solution or leachate containing PGM values and base metals, typically a cyanide solution or leachate. A non-selective precipitation of the PGM values and base metals to form an insoluble precipitate comprising the PGM values and base metals is followed by selective leaching of the precipitate. The selective leaching forms a leach solution containing the base metals and a residue containing the PGM values, or a leach solution containing the base metals and PGM values and a depleted residue. The base metals are recovered from the leach solution and the PGM values are recovered from the residue or the leach solution, depending on the selective leaching. The non-selective precipitation of the PGM values and base metals is carried out by controlled reduction of the pH of the pregnant solution or leachate to a pH of about 2.

Abstract: A heap with precious metal-containing mineral material with precious metal locked within sulfide mineralization is subjected to bio-oxidation followed by acidic thiocyanate leaching to dissolve precious metal. Sulfide sulfur is oxidized during both of the bio-oxidation and the thiocyanate leaching.

Abstract: A sample preparation method for characterization of nanoparticles embedded in the supports of heterogeneous catalysts, with improved particle dispersion, is introduced. The supported catalyst is first ground or milled into fine powder. Then, the powder is mixed into an organic solvent, and an etchant is added to the solvent to digest the supports and release metallic nanoparticles. The resulting solution is then placed in an ultrasonic bath where ultrasonic waves are generated and applied to the solution. The ultrasonic waves suppress agglomeration of the particles and also break up those particle clusters resulting from agglomeration during the prior steps. Subsequently, a sample is extracted from the solution and prepared for analysis.

Abstract: The present invention is directed to a system for recovering metal values from metal-bearing materials. During a reactive process, a seeding agent is introduced to provide a nucleation site for the crystallization and/or growth of solid species which otherwise tend to passivate the reactive process or otherwise encapsulate the metal value, thereby reducing the amount of desired metal values partially or completely encapsulated by such material. The seeding agent may be generated in a number of ways, including the recycling of residue or the introduction of foreign substances. Systems embodying aspects of the present invention may be beneficial for recovering a variety of metals such as copper, gold, silver, nickel, cobalt, molybdenum, zinc, rhenium, uranium, rare earth metals, and platinum group metals from any metal-bearing material, such as ores and concentrates.

Abstract: The present invention is directed to flotation of refractory gold sulfide ores and to pressure oxidized residue neutralization using flotation tailings that have been contacted with an off gas of pressure oxidation.

Abstract: The membrane electrode assemblies of fuel cells are recycled by pulverizing the membrane electrode assemblies into a powder and contacting with acid to leach precious metals. Surfactants can optionally be used to increase yield of precious metals recovered.

Abstract: A process for re-processing of a Fischer-Tropsch catalyst is described comprising the steps of; (i) de-waxing the Fischer-Tropsch catalyst, (ii) subjecting the de-waxed catalyst to hydrometallurgical leaching or extraction to separate catalyst metal or metals from catalyst support material, and (iii) recovering the separated catalyst metal or metals, wherein the de-waxing step is performed using a pressurised near-critical or supercritical fluid under conditions that minimise catalyst metal spinel formation.

Abstract: Precious metals such as gold can be extracted from a refractory ore using a conventional cyanide leaching step and with reduced cyanide consumption by pre-treating the ore prior to cyanide leaching. The refractory ore is pretreated by fine grinding and an initial leaching step which uses inexpensive limestone and lime to maintain the initial leach relatively alkaline. Oxygen is added to the initial leaching step and the conditions are carefully controlled to only partially oxidize the ground ore to between 9-15%. The initial leaching step can be carried out at temperatures of less than 100 degrees C. and at atmospheric pressures. The pre-treated ore is then leached by a conventional cyanide leaching step to recover the precious metal and cyanide consumption can be reduced by more than two thirds.

Abstract: A recovery process for at least one precious metal contained in an ore, includes: comminuting the ore to obtain particles smaller than a predetermined particle size; separating the particles into at least two groups, each group being characterized by a particle size range; and leaching separately each group of particles with a reagent adapted to dissolve the at least one precious metal.

Abstract: A method for the recovery of metal values from a metal value-bearing material containing arsenic and/or antimony and a source of sulphate ions such as sulphide ore or concentrate is disclosed.

Abstract: One object of the present invention is to provide a separation process that enables the efficient separation of selenium, tellurium, and platinum group elements from a material containing selenium/tellurium and platinum group elements. In order to achieve this object, the invention provides a separation process for platinum group elements comprising: a step (A) for treating a material containing selenium/tellurium and platinum group elements with alkali, a step (B) for leaching selenium/tellurium, and a step (C) for separating the platinum group element-containing leaching residue and the selenium/tellurium leachate.

Abstract: The invention relates to a method for obtaining metals from a cobalt and/or nickel arsenic sulfide ore or ore concentrate and/or a cobalt and/or nickel sulfide ore or ore concentrate, according to which the cobalt and/or nickel arsenic sulfide ore or ore concentrate and/or the cobalt and/or nickel sulfide ore or ore concentrate is reacted with sulfur or sulfur arsenic compounds to a reaction product, and dissolving and removing soluble metals and rare-earth metals.

Abstract: A composition for cyanide leaching which comprises at least one nonionic surfactant and a process for extracting metals using the abovementioned composition are described.

Abstract: In a method for leaching gold from copper sulfides, the sulfide ores are first subjected to leaching of copper, thereby producing a leaching residue having 7.9% or less of the copper content. This leaching residue is mixed with a leach liquor, which contains the chloride ion and ferric ion and has 1.9 or less of pH. Gold and copper can be effectively leached from the copper sulfide ores. Ordinarily used oxidizing reagents such as hydrogen peroxide or nitric acid are not used. The gold, copper and iron can, therefore, be leached in a single process and by using an identical leaching liquor. The rate of gold leaching reaction can be enhanced by the co-presence of either copper or bromide ion or both together with the chloride and iron ion.

Abstract: The present invention relates generally to a process for recovering copper and other metal values from metal-containing materials using controlled, super-fine grinding and medium temperature pressure leaching. Processes embodying aspects of the present invention may be beneficial for recovering a variety of metals such as copper, gold, silver, nickel, cobalt, molybdenum, rhenium, zinc, uranium, and platinum group metals, from metal-bearing materials, and find particular utility in connection with the extraction of copper from copper sulfide ores and concentrates.

Abstract: A method of which includes the steps of introducing an acidic solution containing (V), copper, ferric iron and ferrous iron into a first tank of a series of continuously stirred tank reactors and, in the first tank, adding air to the solution; heating the solution to an elevated temperature; recycling a portion of selectively precipitated ferric arsenate compounds to the said first tank; and seeding the solution with ferric arsenate compounds.

Abstract: A method for synthesizing nanosize metallic powders can include providing a metallic precursor. The metallic precursor can include a metal alloy formed having a fugitive constituent and a target metal. The fugitive constituent and target metal are chosen such that the fugitive constituent can be selectively dissolved or removed by leaching with an appropriate solvent while leaving the target metal undissolved. The fugitive constituent can be leached from the metallic precursor to leave a metallic residue which is a mass of nanosize metallic particles made substantially of the target metal. The nanosize metallic particles can then be recovered from the metallic residue either merely by removing the solvent and/or breaking up the mass of nanosize metallic particles. The disclosed methods allow for a convenient avenue for production of nanosize particles from readily formed materials for use in a wide variety of potential industrial and commercial applications.

Abstract: A method of texturing polycrystalline iridium includes the steps of cold/warm working of the polycrystalline iridium at equal to or below its re-crystallization temperature to break up the polycrystalline structure such that the orientation favors one direction (i.e. the <110> direction), and re-crystallizing the iridium such that a majority of grains are aligned in the preferred direction. The textured polycrystalline material is then used in vascular devices such as stents.

Abstract: A process for mutual separation of platinum group metals (PGM), wherein highly stable compounds and steps are used to efficiently remove impurity elements while preventing increase of impurity content relative to that of the PGM in the mother liquor and also preventing decomposition of a chloro complex, and palladium, platinum, iridium, ruthenium and rhodium are separated mutually in such a way that each of the separated PGM has a sufficient purity to be a commercial product.

Abstract: PGMs can be extracted from a source material by heat-treating the source material to form a residue containing PGMs in a cyanide leachable condition and, thereafter, cyanide leaching the residue using a solution containing cyanide to form a pregnant cyanide leach liquor containing PGMs in solution.

Abstract: This invention relates to the recovery of precious metals and, more particularly, to the recovery of precious metals, such as platinum group metals, gold and rhenium, from various sources using a solution comprising at least one ammonium salt, at least one halogen salt and at least one oxidant.

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: Improved methods for the extraction or dissolution of metals, metalloids or their oxides, especially lanthanides, actinides, uranium or their oxides, into supercritical solvents containing an extractant are disclosed. The disclosed embodiments specifically include enhancing the extraction or dissolution efficiency with ultrasound. The present methods allow the direct, efficient dissolution of UO2 or other uranium oxides without generating any waste stream or by-products.

Abstract: Processes are provided for recovering precious metals from refractory materials using thiosulfate lixiviants. The processes can employ lixiviants that include at most only small amounts of copper and/or ammonia and operate at a relatively low pH, reduction of polythionates, inert atmospheres to control polythionate production, and electrolytic solutions which provide relatively high rates of precious metal recovery.

Abstract: This invention relates to the recovery of platinum group metals and, more particularly, to the recovery of platinum group metals from various sources by roasting the source material with one or more of sulfuric acid, a sulfate and/or a bi-sulfate and with one or more halogen salt. The roasted product is put in contact with a leaching solution to dissolve at least a portion of the platinum group metals, which then may be separated and recovered.

Abstract: The present invention relates generally to a process for the production of sulfuric acid and liberation of precious metal values from materials containing sulfur through pressure leaching operations. In accordance with various aspects of the present invention, the sulfur-bearing materials may comprise residues from pressure leaching operations, such as those carried out at medium temperatures. The process of the present invention can be advantageously used to convert such sulfur-bearing materials to sulfuric acid by means of pressure leaching. The sulfuric acid so produced can be used beneficially in other mineral processing operations, for example those at the site where it is produced. Metals, such as precious metals, that are contained within the sulfur-bearing materials advantageously may be recovered from processing products by established precious metals recovery technology.

Abstract: A method to dissolve at least one metal from jarosite or other iron hydroxyl sulphate containing-material which includes the steps of subjecting the material to alkaline treatment in a brine solution to facilitate jarosite decomposition, and acidification of the brine slurry to solubilise the liberated metal.

Abstract: The process of the present invention recovers platinum group metal(s), such as platinum and palladium, from PGM-containing materials containing base metals, such as copper and nickel. The process controls sulfur levels by using solvent extraction 306 to remove acid in the nickel recovery circuit. The acid product 326 can then be neutralized and/or recycled as desired.

Abstract: A method for controlling the extraction of gold from a gold ore by the cyanidation process in which a leaching step including the addition of a lead compound, which is typically lead nitrate or other lead salt, is used. In order to maintain stable conditions in the leaching process, and to use the leaching reagents efficiently, an analysis step is used to monitor the concentration of thiocyanate in the cyanidation step. This value has been found to be directly related to the rate of addition of the lead compound in the pre-leaching or leaching step. Further, the rate of addition of lead compound is also directly related to both the time required for, and the efficiency of, the cyanidation step. By establishing a target value, and a preferred range, for the thiocyanate concentration based on the properties of the ore being processed, optimal extraction conditions can be established in the leaching process and maintained by monitoring the thiocyanate concentration.

Abstract: The present invention relates to a method of synthesizing lignosulfonic acid-doped polyaniline by oxidatively polymerizing aniline in the presence of transition metal ions selected from the group consisting of Ag(I), Fe(II), and Fe(III) salts. The present invention also relates to a method for the preparation of transition metals from transition metal salts by exposing transition metal ion containing materials to an aqueous dispersion of lignosulfonic acid-doped polyaniline.