Abstract: An air-water concentration cell is provided as follows. A cathode electrode is formed of a first material for catalyzing an oxygen reduction reaction (ORR). An anode electrode is formed of a second material for catalyzing an oxygen evolution reaction (OER). A proton conductive membrane is interposed between the cathode electrode and the anode electrode. A fuel reservoir is interposed between the proton conductive membrane and the anode electrode. The fuel reservoir contains water. The water of the fuel reservoir is in contact with the anode electrode and the proton conductive membrane.

Abstract: A process for the extraction of a precious metal, such as gold or silver, from a sulphide ore or concentrate or other source material comprises subjecting the source material to pressure oxidation to produce a pressure oxidation slurry. The pressure oxidation slurry is flashed down to a lower temperature and pressure and is then subjected to a liquid/solid separation to obtain a pressure oxidation solution and a solid residue containing the precious metal. The solid residue is then subjected to cyanidation to extract the precious metal. The formation of thiocyanide during cyanidation is minimized or counteracted by effecting the cyanidation at an elevated oxygen pressure and a reduced retention time, such as 30 to 90 minutes. A method for the reduction of copper cyanide formation during cyanidation leaching is also provided.

Abstract: A fuel cell includes an anode, a cathode, and an electrolyte membrane arranged between the anode and the cathode. A fuel deficiency countermeasure is implemented for the anode and a fuel deficiency countermeasure is implemented for the cathode. As a result, the fuel cell suppresses a decline in performance caused by a fuel deficiency.

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 shown for raising the pH of a cyanide leach solution of the type used in a heap leaching mining operation. Lime slurry is mixed with a side stream of barren cyanide solution in a reactor vessel in order to remove carbonate hardness, to regenerate the hydroxide alkalinity and to raise the pH of the resulting recausticized leach solution. A portion of the calcium carbonate precipitate formed in the reactor vessel is retained in order to encourage further crystal growth. Overflow from the reactor vessel passes through one or more cyclone separation stages in order to remove particulate solids. A cyclone overflow stream is directed back to the process to upwardly adjust the pH of the bulk of the barren cyanide solution. A cyclone underflow stream is directed back to the reactor vessel to provide seed crystal nuclei for precipitate growth.

Abstract: A process for the extraction of a precious metal, such as gold or silver, from a sulphide ore or concentrate or other source material comprises subjecting the source material to pressure oxidation to produce a pressure oxidation slurry. The pressure oxidation slurry is flashed down to a lower temperature and pressure and is then subjected to a liquid/solid separation to obtain a pressure oxidation solution and a solid residue containing the precious metal. The solid residue is then subjected to cyanidation to extract the precious metal. The formation of thiocyanide during cyanidation is minimized or counteracted by effecting the cyanidation at an elevated oxygen pressure and a reduced retention time, such as 30 to 90 minutes. A method for the reduction of copper cyanide formation during cyanidation leaching is also provided.

Abstract: Methods for inhibiting depletion of mineral values from pregnant lixiviant solutions comprise contacting the requisite metal ore with a preg-robbing inhibition agent (PRIA) comprising (I) alkyl polyglucoside surfactants; (II) imidazoline based amphoteric surfactants; (III) hydroformylation products of lower (C2–C8) alkanes in an organic solvent medium, and (IV) esters and aldehydes.

Abstract: In a process for hydrocarbon steam reforming, a primary reformed gas is produced from a mixed gas of hydrocarbon and steam with use of a primary reforming means including an external combustion type of reforming furnace. A secondary reforming reaction of the primary reformed gas is carried out in the presence of air and/or oxygen. A burner assembly of the reforming furnace comprises burners for heating reforming tubes of the furnace and regenerators for preheating a combustion air flow to the burners. Combustion exhaust gas of the reforming furnace heats the second regenerator for preheating the combustion air to the second burner, while the first burner is in firing operation, whereas the combustion exhaust gas heats the first regenerator for preheating the combustion air to the first burner, while the second burner is in firing operation. The flow passage for the combustion exhaust gas is so controlled as to be switched to either of first and second flow passages in a predetermined time interval.

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: 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: 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: A mixture of silicon and phosphorus are reacted with halides to produce silicon tetra halide, silicon-phosphorus halides and phosphorus trihalide composition. This composition is reacted with any suitable organic or inorganic-organic compound which has an active hydrogen, halide and/or a metal radical to produce organic silicon-phosphorus halides compositions which will react with inorganic, inorganic-organic and organic compound to produce an organic silicon-phosphorus product. These products may be used as flame-retardants, hydraulic fluid, building components, coating agents, adhesives and many other uses.

Abstract: Provided is a process for treating refractory precious metal-containing ores, particularly gold-bearing ores, which are refractory due to the presence of organic carbon, to reduce the ability of organic carbon to interfere with recovery of the precious metal. The ore may also contain sulfide materials with which the gold is associated and from which the gold is difficult to separate. The ore is comminuted to a size at which at least about 80 weight percent of the ore is smaller than about 40 microns in size. The comminuted ore is then slurried and subjected to pressure oxidation at severe operating conditions. The treating temperature is greater than about 190.degree. C. When sulfide minerals are present, substantially all of the sulfide sulfur must first be oxidized prior to obtaining significant benefit from the treatment of the organic carbon. Greater than about 96% of the sulfide sulfur must be oxidized.

Abstract: A process is provided for recovering gold from refractory sulfide ores. Preferred feed materials have multiple different sulfide mineralogies, with gold being primarily contained within one or more, but not all, of the sulfide mineralogies. Sulfide mineralogies with the highest gold values are preferentially oxidized, while those sulfide mineralogies with relatively little gold remain largely unoxidized. In one embodiment, dissolved arsenic following pressure oxidation is precipitated as ferric arsenate through the control of pH during neutralization. In another embodiment, the oxidized slurry following pressure oxidation is contacted with an oxidizing agent to convert at least a portion of ferrous iron to ferric iron. Following, pressure oxidation, the slurry can be subjected to cyanidation recovery of gold, and liquid from the tailings stream can be recycled upstream of the pressure oxidation step in a substantially untreated form.

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: Platinum group metals, gold and silver are extracted from complex ores, automobile scrap, refractory ores and as naturally occurring by leaching the precious metal containing materials with a solution containing halogen salts such as potassium or sodium iodide and bromide in the presence of ammonium ions and oxygen. The precious metal containing materials and reactants are charged into a reaction zone held at high temperatures and pressures to form a slurry containing a precious metal ion solution. The precious metal ion solution is separated from the slurry and subjected to recovering techniques to recover the precious metals.

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 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: 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 hydrometallurgical processing of friable concentration products containing precious nonferrous and ferrous metals comprising preliminary magnetic separation of friable products to pass ferrous metals into the magnetic product and to produce a nonmagnetic fraction containing nonferrous and precious metals. The nonmagnetic fraction is treated with an alkali solution in the autoclave at 80.degree.-190.degree. C. and an oxygen pressure of 0.1-0.8 MPa, passing aluminium into the solution and obtaining a solid sediment. The sediment is treated with a sulfuric acid solution in the autoclave under a surplus oxygen pressure, passing nonferrous metals into the solution and producing enriched concentrate of precious metals in the solid sediment.

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.

Abstract: Gold and silver are extracted from their elemental state or from complex ores and alloys by leaching them with a solution containing ammonia, ammonium salts and one or more oxidants. The process is particularly effective for refractory gold ores including sulfide and carbonaceous ores.

Abstract: A process for removing and recovering cyanide from a cyanide-containing mixture. The process includes the steps of adjusting the pH of the cyanide-containing mixture to between about 6 to about 9.5, volatilizing the HCN contained in the pH adjusted mixture and contacting the volatilized HCN with basic material. Preferably, the cyanide recovery process is performed on tailings slurries resulting from metal recovery processes.

Abstract: A process for removing and recovering cyanide from a cyanide-containing solution. The process includes the steps of adjusting the pH of the cyanide-containing solution to between about pH 6 and about pH 9.5, volatilizing the HCN contained in the pH adjusted solution and contacting the volatilized HCN with basic material. Preferably, the cyanide recovery process is performed on tailings slurries resulting from metal recovery processes.

Abstract: Precious metal values, particularly gold and silver, are liberated from refractory, carbonate ores by adjusting the molar ratio of sulfide to total acid consumers to between about 1.2 and about 3.2 in the ore feed to a pressure oxidation process. The ore is contacted with oxygen to oxidize sulfide in the ore with at least about 65 percent of the sulfide oxidation occurring in a first oxidation zone at a temperature above about 360.degree. F. The oxidation of sulfide forms at least about 5 grams of free sulfuric acid in the first oxidation zone. The oxidation process is continued in subsequent oxidation zones. A gas stream is removed from the oxidation zones and oxygen is separated from carbon dioxide and other inerts in the gas stream and the purified oxygen is recycled to the oxidation zones.

Abstract: Gold in a very dilute water solution is carbon filtered to capture the gold by adsorption; the gold in the filter is then recovered from the carbon by means of a highly-efficient non-explosive low-alcohol water-based eluant including a strong base and an elevated level of sodium or potassium cyanide.

Abstract: Carbonaceous ore containing a precious metal (gold) is treated with an aqueous solution of chlorine dioxide to enhance the recovery of the precious metal.

Abstract: Refractory carbonaceous sulfide ores are treated in a manner so as to improve gold recovery by a treatment in specific combination of steps whereby the ore is treated with chlorine after pretreatment and before cyanidation; the particular steps in the treatment of the ore have been found to be necessary as the conventional pretreatment will not improve the yields on any economic basis.

Abstract: Gold-containing ores, having refractory sulfidic matter or a combination of refractory sulfidic matter and refractory carbonaceous matter, are processed to recover their gold values. The process uses an ore roasting procedure that utilizes a two-state, fluidized bed roaster. The process also employs a pure oxygen atmosphere during roasting. A carbon-in-leach step is desirably used to extract gold values from the roasted ore.

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

Abstract: A process is described for leaching ores or concentrates containing one or more metallic sulphides .with a circulating liquor so as to solubilize desired metal values therefrom, if said metal values are capable of dissolution in an acidic ferric sulphate solution (e.g. copper), or so as to render the desired metal values (e.g. gold) more accessible to subsequent processing, in each case by effecting metallic sulphide dissolution from the ore or concentrate.

Abstract: A process for recovering a first metal, e.g., gold, from a carbonaceous ore comprising contacting the ore with an added metal component other than an alkali metal or alkaline earth metal component in an amount effective to at least promote the oxidation of carbonaceous material in the ore, the contacting occurring at conditions effective to (1) chemically oxidize at least a portion of the carbonaceous material, and (2) at least partially liberate the first metal from the ore; and recovering the first metal from the ore.

Abstract: A process for at least one of (1) recovering at least one first metal other than manganese from a first ore containing reducible manganese, and (2) recovering at least one second metal from a second ore containing the second metal and at least one metal sulfide of a metal other than the second metal and manganese; the process comprising at least one of: (A) contacting the first ore with an aqueous composition and a material containing at least one metal sulfide in the presence of a metal redox couple more positive than about +0.1 versus the standard hydrogen electrode, W. M.

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 gold recovery pretreatment process is disclosed in which the gold content is more completely extracted from refractory sulfidic ores which contain large quantities of metal carbonates such as dolomite than occurs in traditional gold extraction methods. The process includes treating the ore in an autoclave at elevated temperature and oxygen overpressure conditions in the presence of soda ash or other alkaline materials. The autoclaving of the slurried ore is performed for a sufficient amount of time to oxidize the sulfidic compounds in the ore. The oxidized ore is then more amenable to subsequent conventional gold extraction techniques.

Abstract: In this invention sulfide compounds are added to mercury and precious metal-containing carbonaceous ore slurries prior to the slurry being processed by a carbon-in-pulp system. The sulfide compound inhibits the mercury from being adsorbed onto the activated carbon by reacting with the mercury to form mercuric sulfide and by inhibiting the dissolution of mercury from the ore. The mercuric sulfide precipitate displays no activity toward the activated carbon. The sulfiding procedure is performed with a sufficient amount of sulfide-providing compound to provide at least about 30 times the stoichiometric amount of sulfide ions required to react with the mercury in the ore slurry.

Abstract: Low-grade refractory gold ores, which may also contain silver and other metal values are treated by partial roasting of concentrate to remove controlled amounts of sulfur and carbon, then oxygen pressure leached to oxidize further amounts of sulfur and carbon and to dissolve base metals and a portion of any silver present, and the residue is then cyanided to dissolve gold and remaining silver which are then recovered.

Abstract: A method and system for the percolation leaching of gold and silver ores applies a cyanide leaching liquid to a pile of gold and silver ore. Heap leaching, vat leaching, or the like may specifically be practiced. The cyanide leaching liquid is applied to the pile by spraying, flooding, or via a foam of oxygen gas and cyanide liquid on top of the pile. Gold and silver are recovered from the pregnant liquor. The leach rate is increased and/or the recovery of gold and silver from the ore is increased by supplying to the pile a gas containing oxygen at a significantly higher percentage than in ambient air (e.g. pure oxygen gas). The oxygen gas may be supplied to the leaching liquid, and/or into the pile itself (as with a plurality of perforated pipes adjacent the bottom of the pile).

Abstract: Gold values are obtained from gold cyanidation tailings or gold bearing ores by treating the same with a flotation collector consisting of 5 to 20% xanthate collector and 80 to 95% fatty acid collector of a pulp pH range from 5 to 8.

Abstract: The invention relates to a process for the recovery of gold from an alkaline aqueous liquid solution containing gold-cyanide ion, and possibly silver and/or copper and/or mercury, which comprises adding a quantity of thiourea to the solution so as to allow formation of a gold complex with thiourea which gold complex is soluble and stable in dilute acid solution, then adjusting the pH of the solution to make the solution mildly acidic, whereby gold and mercury remain in solution in the liquid and silver and/or copper is incorporated in a precipitate containing silver and/or copper cyanide compounds, and then separating the precipitate from the liquid to leave a solution of dissolved gold complex and subsequently recovering the gold from the solution.

Abstract: A process for the extraction of silver and gold from refractory ore is disclosed. The process includes first grinding the refractory ore. This ground refractory ore is subsequently treated with an alkali solution of a stoichiometric excess amount of sulphide in relation to the amount of gold and silver contained in the refractory ore, to thus form a pulp containing a gold and silver sulfide. The pulp and alkaline solution ore are aerated to oxidize the excess sulfide to sulfate and then a mixture of the pulp and cyanide liquor are formed. Finally this mixture is aerated to obtain a final gold and silver product.

Abstract: A process for the recovery of silver from a residue essentially free of elemental sulphur obtained by acidic pressure oxidation leaching or iron-containing sulphidic material which comprises forming a slurry of the residue with lime at a temperature of at least about 80.degree. C. to raise the pH of the slurry to at least about 9. The slurry is maintained at this temperature for from about 0.5 to about 4 hours, and the resultant slurry is subjected to silver recovery treatment.

Abstract: Metal is removed from particlized metal bearing refractory ores in an efficient manner utilizing pressure metallurgy with heat recovery. The particlized ore is mixed with a heated liquid, and preferably a flocculant and fibers, to form a slurry. The ore in the slurry is oxidized at superatmospheric pressure, and elevated temperatures (e.g. around 300.degree. F.). The oxidized ore is washed to remove acids, and like products of oxidation, and the washed ore is subsequently subjected to conventional leaching processes to effect an actual metal recovery. Heat recovery is practiced by utilizing spent wash water as part of the slurrying liquid, and using two or more liquid-interconnected vessels in effecting the oxidization.

Abstract: A process for recovering gold from refractory auriferous iron containing sulphidic material which comprises treating an aqueous slurry of the material in a pressure oxidation step at a temperature in the range of from about 135.degree. to about 250.degree. C. under a total pressure of from about 500 to about 5000 kPa to oxidize sulphide sulphur to sulphate form and release gold from a refractory state. The pH of the resultant oxidized slurry is adjusted to a value suitable for cyanidation. The pH adjusted slurry is subjected to a cyanidation step in which gold is dissolved in a cyanide solution. The cyanided slurry is diluted to a pulp density in the range of from about 2 to about 10% solids by weight. The diluted slurry is subjected to a liquid-solids separation step to produce a gold containing solution and a relatively high pulp density gold-containing slurry, and gold from the gold-containing solution and from the high pulp density gold-containing slurry is separately recovered.

Abstract: A process for separately recovering gold and silver from a solution containing dissolved gold and silver by carbon adsorption which comprises passing the solution sequentially through a series of carbon adsorption stages and passing carbon sequentially through the series countercurrent to the solution to cause gold and silver to be loaded onto the carbon. A portion of the loaded carbon is removed partway along the series, and silver is recovered from the removed portion of the loaded carbon. Loaded carbon is removed from the beginning of the series, and gold is recovered from the carbon removed from the beginning of the series. Carbon from which gold and silver have been removed is returned to the end of the series for re-use.

Abstract: A process for the recovery of gold from refractory auriferous iron-containing sulphidic material which comprises providing an aqueous feed slurry of fresh feed material and oxidized solids from a subsequent pressure oxidation step. The feed slurry has a pulp density in the range of from about 30 to about 60% by weight. The slurry is subjected to pressure oxidation at a temperature of from about 120.degree. to about 250.degree. C. under a total pressure of from about 360 to about 6000 kPa to produce a slurry of oxidized solids. A portion of the oxidized solids is recycled to the feed slurry, and gold is recovered from the remaining oxidized solids.

Abstract: A process is described by which copper and optionally silver and gold are recovered from sulfide and oxide ores, concentrates or slag, which contain the metals. The particulate materials are treated with an aqueous solution of an alkali cyanide or alkaline earth cyanide, the laden solution is filtered, if desired, a water-soluble sulfide compound is added to the laden solution or filtered laden solution, the laden solution is subsequently adjusted to a pH value below 5 by an addition of acid to precipitate the metal sulfide, which is filtered off, and the resulting hydrocyanic acid is recovered. The process steps of precipitation and filtration of the metal sulfide and the recovery of the free hydrocyanic acid contained in the filtrate are carried out under superatmospheric pressure of 1.5 to 15 bars. The precipitation is preferably effected at a pH value of 1.5 to 2.0. The free hydrocyanic acid is recovered as alkali cyanide or alkaline earth cyanide and is recirculated to the leaching stage.