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

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

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

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

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

Abstract: A process for recovering gold and silver from refractory ores containing precious metals locked in sulfide and arsenide minerals including roasting a concentrate of said sulfide and arsenide minerals with lime at a temperature of about 600.degree. C. Thereafter the resultant calcine is ground, leached with cyanide and precious metals are recovered from the cyanide solution.

Abstract: The present invention is directed to an improvement in a process for the recovery of gold from refractory sulfidic auriferous ores which comprises oxidizing a slurry of ore with oxygen gas under pressure in the presence of sulfuric acid, neutralizing the oxidized slurry, cyanidizing the neutralized slurry to leach gold therefrom, and recovering gold from the resultant leachate. In accordance with the improved process, the oxidation of the ore slurry is carried out in a manner whereby, after a startup phase during which oxidation is initiated, the amount of sulfuric acid added to the ore slurry is sufficient to insure the oxidation of that portion of the sulfide sulfur in the ore which will allow recovery, by cyanide leaching, of at least about 80% of the gold in the ore. The oxidized slurry can be neutralized without a washing operation.

Abstract: A process for treating copper containing precious metal ores prior to cyanidation and recovery of the precious metal eg gold. The process involves addition to the ore before or after milling of a water soluble or water dispersible surface active agent in the form of a fatty alkyl amine preferably an ethoxylated fatty alkyl amine. The agent reduces the high cyanide consumption, which is caused by copper dissolution, by passivating the mineral surface.

Abstract: A method for reducing the amount of anionic metal-ligand complex in a solution comprises: (a) contacting the solution with a substance selected from: a compound having the formula: A.sub.w B.sub.x (OH).sub.y C.sub.z.nH.sub.2 O, wherein A represents a divalent metal cation, B represents a trivalent metal cation, C represents a mono- to tetravalent anion, and w, x, y, z and n satisfy the following: 0.ltoreq. z.ltoreq.x.ltoreq.4.ltoreq.w.ltoreq.1/2y and 12.gtoreq.n.gtoreq.1/2(w-x); a calcined product of said compound and mixtures thereof; and (b) separating the substance from the solution. A method for removing substantially all metal-cyanide, -thiocyanate, -thiosulfate, -citrate and/or -EDTA complex from a solution containing one or more of said complexes is also disclosed.

Abstract: A process for adsorbing gold from a leach pulp by means of activated carbon is described in which the leach pulp (the leach solution together with the subdivided gold bearing ore) is diluted to a specific gravity of less than that of the activated carbon and is subsequently passed upwardly through a multistage liquid/solid contacting column. The contacting column is of the type having perforated plates or trays defining a series of vertically adjacent stages and the operation of the column has a cycle which includes a first part during which upward flow of diluted pulp fluidizes the activated carbon, a second part in which the carbon is allowed to settle on the trays and a third part during which a reverse flow of diluted pulp carries carbon downwardly through the column from one stage to another. In the third part of the cycle, loaded carbon is removed from the lowermost stage and treated to recover adsorbed gold therefrom.

Abstract: There is disclosed an activated carbon for use in the process of recovery of gold which comprises adsorbing aurocyanide complexes thereon, desorbing the complexews therefrom and separating the activated carbon with a screen, the activated carbon being spherical and having a diameter of more than the opening of the screen but of not more than 2 mm; an iodine number of not less than 950 mg/g as determined by JIS K 1474-1975; and a hardness of not less than 99% as determined by JIS K 1474-1975.Also disclosed is an improved, high efficient process of the recovery of gold which uses such a spherical activated carbon.

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 process is provided for the reduction roasting of ores using a C.sub.2 to C.sub.8 hydrocarbon. The process is particularly applicable to manganese dioxide containing ores and provides enhanced reduction of the manganese to lower oxidation states at low operating temperatures for manganese dioxide ores and provides increased silver recoveries from refractory manganese-silver ores.

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 system for removing cyanide and related species from a cyanide-containing waste fluid, for example, of the sort generated by mining operations, includes means for generating hydrogen peroxide by the burning of a fuel and the quenching of that burning with the waste fluid. At least a portion of the cyanide content of the waste fluid is eliminated by oxidation with the hydrogen peroxide, and the quenching can also provide organic material to serve as a carbon source for microbes which degrade residuel cyanide in the treated waste stream.

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: An agglomerative heap leaching method for recovering gold, silver or other metals from low grade refractory ores. Hypochlorite compounds are incorporated directly into the ore agglomerates as they are formed. This provides ample time and opportunity for the hypochlorite to destroy, modify or passivate refractory components of the ore thereby improving metal recovery in the subsequent cyanide leaching step.

Abstract: A system for heap leach mining comprises supply and header pipes for conducting a leaching solution alongside a bed or "heap" of crushed metal-laden ore deposited on an impervious pad. A series of spaced tubes are connected to the supply and header pipes to extend transversely thereof, over the pad, to receive the leaching solution therefrom. A plurality of emitters are connected in spaced relationship along each of the tubes for emitting the leaching solution at a controlled and substantially uniform rate over the pad and into the ore bed. At least some of the emitters are adjustable whereby different sets of flow passages can be utilized. The adjustable emitter comprises a sleeve slip-fit and rotatably mounted in a housing for rotative adjustment between at least two positions to alternately communicate the sets of flow passages with an inlet to the emitter.

Abstract: The invention relates to a method and apparatus for extracting gold from gold ore. The apparatus and process save capital and operating costs in the extracting of gold from gold ore and include comminution and leaching of the ore, and more particularly the apparatus and process reduce the costs for the ore grinding, and make a fine ore grinding superfluous without having to accept a reduction in the gold yield during leaching. The gold ore is subjected to a product bed stressing and interparticle crushing in the nip of a high-pressure roller press before being leached and the product that has been product-bed-comminuted and subjected to interparticle crushing and the product agglomerates thereby formed are piled on a heap that is sprayed with a lixivium.

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: Heap leaching of gold/silver ores with an aqueous alkali cyanide solution containing a surfactant hydrolyzable at the pH of the solution, the surfactant being present in an amount sufficient to increase the rate of metal value recovery without adversely affecting the carbon efficiency in the subsequent step of separating the metal cyanide value from the pregnant leach solution by absorption on carbon columns.

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: A process and apparatus for the recovery of metals such as silver from phosphate flue dust. The process includes the steps of blending chloride salt and the flue dust to produce a blended material, roasting the blended material in an oxygen bearing atmosphere to oxidize carbon in the blended material producing a gas and to react chloride salt with the metal in the blended material producing a water soluble metallic salt, dissolving the metallic salt in water to produce a solution, filtering the solution to remove solids, and precipitating metals from the filtered solution with the precipitate ready for conventional smelting. The preferred embodiment of the apparatus includes a flue dust hopper and mill and a salt hopper and mill for feeding the dust and salt to a radiant tube dryer and a radiant tube asher for blending and roasting the materials, and a spray chamber at the outlet of the asher for separating solids and gases, where certain of the solids go into solution.

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 method for reducing the amount of anionic metal-ligand complex in a solution comprises: (a) contacting the solution with a substance selected from: a compound having the formula: A.sub.w B.sub.x (OH).sub.y C.sub.z .multidot.nH.sub.2 O, wherein A represents a divalent metal cation, B represents a trivalent metal cation, C represents a mono- to tetravalent anion, and w, x, y, z and n satisfy the following: 0.ltoreq.z.ltoreq.x.ltoreq.4.ltoreq.w.ltoreq.1/2y and 12.gtoreq.n.gtoreq.3/2x; a calcined product of said compound and mixtures thereof; and (b) separating the substance from the solution. A method for removing substantially all metal-cyanide, -thiocyanate, -thiosulfate, -citrate and/or -EDTA complex from a solution containing one or more of said complexes is also disclosed. The latter method comprises contacting the solution with a sufficient amount of substance consisting essentially of a compound selected from: hydrotalcite, calcined hydrotalcite and mixtures thereof.

Abstract: There is disclosed a process and an apparatus for beneficiating a mineral ore, such as phosphate-containing ore, in a substantially vertical column. The feed subjected to the benefication preferably has a particle size of less than 20 mesh. The feed is introduced into the column, containing at least one baffle, into which there is also introduced a gas at the bottom portion thereof and a liquid through at least one column inlet at the top of the column. The baffle and the rates of introduction of the feed, the gas, and the liquid are such as to create relatively high turbulence conditions within the column. The enriched, beneficiated product is removed at the top of the column, while the waste products, such as silica-containing material, in the case of a phosphate ore, are recovered at the bottom of the column.

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: 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 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 the hydrometallurgical recovery of gold and silver by direct oxidizing sulphuric acid-digestion of arsenopyrite-concentrates (FeAsS.sub.2) containing carbonaceous materials with a silicate gangue, and/or a silicate and pyrite gangue whereby arsenic and iron are fully solubilized and the noble metals are quantitatively enriched in the silicate-residue. The concentrate is subjected to mechano-chemical stress to produce structural deformations before being digested in the presence of oxygen. After decarbonization of the residue, gold and silver can be recovered by cyanide leaching without losses due to adsorption. A bulk process for preparing gold and silver rich concentrates is also disclosed.

Abstract: A process for thickening gold ore slurries or slimes for gold purification which comprises adding to such gold ore slimes an effective amount of flocculant comprising a terpolymer containing 5-35 mole % 2-AMPS, 5-45 mole % sodium acrylate and 50-90 mole % acrylamide, said terpolymer having an RSV of at least 20.

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 method for recovering precious metals from ore is disclosed. Ore is treated in an acidic slurry with an activated oxygen mixture obtained from an ultraviolet light ozone generator. The activated oxygen frees chemically bonded precious metals creating an expanded, hydrated ore so that the metals may be oxidized and leached out using standard leaching techniques. In addition, the activated oxygen aids in the leaching process. Substantial increases in the amount of precious metal recovered from a given amount of ore result.

Abstract: A novel system for chemically leaching ore that decreases pollution to the environment and that enhances reaction kinetics and economic considerations. An impervious covering (18) blankets a distribution network of drip lines (17) laid over the ore heap (14). A lixiviate containing solution is forced by means of a pump (11) through a venturi eductor (19) into the distribution network of drip lines (17) for application to the ore heap (14). After percolating through the ore heap (14), the leach solution is recycled through a recovery system (16) to the venturi eductor (19).

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: A process is described for the substantially complete recovery of cyanide reagent and metal forming water soluble metal-cyanide complexes contained in mill effluents and waste waters. The process is comprised of a loading cycle wherein the metal-cyanide complexes are adsorbed onto a basic ion exchange resin and the free cyanide containing column effluent is returned to the mill. The metal ions, which are usually mostly copper, nickel and zinc, and the complexing cyanide are eluted in the subsequent regenerant cycle by an acid solution having controlled pH and controlled redox potential, the latter being measured against the saturated calomel electrode. The preferred oxidant to control the redox potential of the regenerant solution is hydrogen peroxide. The generated hydrogen cyanide is sparged with air, or removed by subatmospheric pressure from the regenerant solution, and dissolved in an alkaline scrubber solution for reuse. The metal ions are recovered from a bleed solution.

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 is provided for the recovery of precious metals, such as gold and silver, from refractory sulfidic material and refractory carbonaceous sulfidic material. The sulfidic material is pulped and bioleached using either facultative or obligate thermophiles at temperatures in excess of about 45.degree. C. and ranging up to about 90.degree. C. The residue remaining from the bioleach is neutralized and washed and the precious metals therein recovered by dissolution.

Abstract: Production of elementary sulphur from an iron sulphide mineral, which comprises oxidizing acid lixiviation of the pulverized mineral, for extraction of the sulfur. The pulp obtained from the lixiviation is treated in the hot with an organic solvent for sulphur, the solvent having a density higher than 1, to separate this pulp into an aqueous phase containing in solution the non-ferrous metals, the sulphates of which are water soluble, and into a suspension of the solid of the pulp in an organic phase consisting of a solution of sulphur in the solvent separated by decantation and, after separation of the solid in suspension in the organic phase, the sulphur is recovered by crystallization after cooling of the organic phase.

Abstract: This invention is a process for removing mercury from the desorption or cyanide liquor of a precious metal recovery, cyanide leach system. A sulfide ion-producing compound and a flocculating agent are added to the desorption liquor to form and flocculate mercuric sulfide. The desorption liquor typically has a cyanide concentration of between about 0.5 percent and about 2.0 percent by weight. The flocculated mercuric sulfide is separated from a substantially mercury-free precious metal-containing, cyanide solution.

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).