Abstract: A method of improving metal leach kinetics and recovery during atmospheric or substantially atmospheric leaching of a metal sulfide is disclosed. In some embodiments, the method may comprise the step of processing a metal sulfide concentrate in a reductive activation circuit 220 that operates at a first redox potential, to produce a reductively-activated metal sulfide concentrate. The method may further comprise the step of subsequently processing the activated metal sulfide concentrate in an oxidative leach circuit 240 to extract metal values. In some disclosed embodiments, reductive activation steps and/or oxidative dissolution steps may employ mechano-chemical and/or physico-chemical processing of particles or agglomerates thereof. Reductive activation may be made prior to heap leaching or bio-leaching operations to improve metal extraction. Systems for practicing the aforementioned methods are also disclosed.

Abstract: The present invention relates to aqueous processes to make metal chalcogenide nanoparticles that are useful precursors to copper zinc tin sulfide/selenide and copper tin sulfide/selenide. In addition, this invention provides processes for preparing crystalline particles from the metal chalcogenide nanoparticles, as well as processes for preparing inks from both the metal chalcogenide nanoparticles and the crystalline particles.

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: Disclosed is a solid/liquid reaction process comprising the steps of: a) forming a slurry of a solid and a solution containing a species (SA) reactive with the solid and convertible to a species in the gas phase (SG); b) conducting a reaction between the solid and the species SA in a slurry in a vessel; and c) controlling a process condition of the slurry to minimise reactive conversion of species SA to species SG. Reactive conversion of species SA to species SG in the vessel is minimised by the placement of laminar slurry cover buoyant with respect to the slurry in the vessel. A process of particular importance is the process of cyanidation of gold ores in which reactive conversion of aqueous cyanide (CNaq?) to HCN (g) is a particular problem. A vessel (1, 2, 3) and leach circuit for conducting the solid/liquid process is also disclosed.

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: 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: A method for reducing consumption of cyanide and level of carbon fouling during cyanide extraction of gold and silver from their ores by treating the ore or aqueous slurry of the ore with a water-soluble sequestering agent for the base metal species for a time sufficient for the sequestering agent to react with at least a portion of the base metal species.

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: A process and apparatus for recovering metal values from ores is described. Comminuted ores are mixed with a liquid to form a pulp. A plurality of streams of pulp are then projected against one another, thereby causing erosion of ore particles in the pulp. A pair of pulp streams preferably emit through nozzles 68, 70 which are coaxially aligned with each other. The nozzles are located in any impact chamber 66. Gas may be supplied to the impact chamber through a gas inlet 72. The chamber may be kept at an elevated pressure, and the gas may be selected in order to facilitate the reaction of reagents in the pulp with the ore. Pulp from the impact chamber passes into a co-axial vertical tube assembly 78, 80 from where it passes back to a tank 50 for continued treatment.

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 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: 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: 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: A method and apparatus for treating mineral-bearing ores and, more particularly, for treating ores containing precious metals, base metals and the like values by providing a means to extract the metal or other values from a particulated ore by classifying the ore to separate values from the gangue, and by continuously chemically leaching the said values from the ore. In accordance with an embodiment of the invention, particulated ore is fluidized and intermittently moved through a tank to classify the ore particles into strata according to size, shape and density to beneficiate values, either heavier or lighter than the gangue, for recovery of concentrated values.

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: A method of treating a gold-bearing ore to render the gold component of the ore more amenable to standard cyanidation treatment in a reduced amount of time is disclosed. An aqueous slurry of the gold-bearing ore is introduced into at least one vessel. An oxidizing agent, such as chlorine gas, an alkali metal hypochlorite and an alkaline earth metal hypochlorite, is rapidly introduced into the vessel so that it intimately contacts the aqueous slurry. While the oxidizing agent is being introduced into the vessel, the slurry is agitated with agitating means including a plurality of impeller blades that provide high shear agitation and a large interfacial surface area between the oxidizing agent and the liquid phase of the slurry to enhance the mass transfer of the oxidizing agent so that it becomes substantially completely adsorbed by the aqueous slurry in about 5 to about 15 minutes.

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: A method for leaching gold and/or silver out or other precious metal containing substance using cyanide-containing leaching solutions and adding an aqueous H.sub.2 O.sub.2 solution to accelerate leaching. The total amount of the hydrogen-peroxide solution required for leaching is fed into the leaching slurry at the beginning of leaching. The amount of the H.sub.2 O.sub.2 solution is determined in that the H.sub.2 O.sub.2 is added in a 0.6 to 2.5-fold stoichiometric ratio to the cyanide concentration of the leaching slurry. The pH value of the leaching slurry is set and maintained at between 7 and 10 or between 11 and 13.

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 of recovering a precious metal from an ore comprises treating the ore with a cyanide solution and simultaneously treating the ore with mercury to cause amalgamation with the precious mineral.

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: This invention relates to a hydrometallurgical process for recovering the values contained in metallurgical residues, such as anode mud. In the first step of the process the residue is leached with an alkali carbonate bearing cyanide solution in the presence of an oxidizer, with agitation. The resulting pregnant solution is separated from the barren solids, and subsequently treated for the recovery of the value metals. In the preferred embodiment the recovery is conducted in an electrolytic cell, but known ion exchange processes are equally suitable. The reagent solution is then passed through an ion exchange system to remove trace metal residuals, impurities and degradation products. Next the original chemical composition of the now barren extractant is restored by chemical replenishment or addition, and the regenerated reagent is recirculated for contact with fresh residue and oxidizer.

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: Gold and/or silver is leached from comminuted ore with an alkaline cyanide lixiviant at a superatmospheric pressure of at least 25 bar and with high purity oxygen (at least 90% pure) to reduce the residence time at high yield.

Abstract: Cyanic extraction of precious metal from comminuted, refractory precious metal ore as well as refractory precious metal concentrates and tailings from such ore is effected with rapidity and high yield by agitationally treating the refractory material with an aerated, alkaline solution containing a high concentration of water soluble cyanide and a low concentration of chemical oxidizer such as potassium permanganate.

Abstract: There is provided a method for simultaneously carrying out pulverization of ores and their leaching or extraction within a vertical abrasion mill.