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: 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 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 method is provided for recovering gold and silver from precious metal bearing materials including ores, leaching residues, flue dust, electronic scrap, jewelry scrap, etc. In the method, the gold and silver are extracted from the precious metal bearing materials with a thiourea solution to form a thiourea leach, and the thiourea leach is contacted with carbon to adsorb the gold and silver and provide loaded carbon. The method is characterized by the step of contacting an alkaline solution of thiousulfate ion with the loaded carbon thereby desorbing the precious metals form the carbon. In one modification of the method, an additional step includes adding a salt to the aqueous thiousulfate solution. When needed, the method includes the step of protecting the thiousulfate ion from oxidizing agents. This is done by adding a reducing agent such as sodium sulfite to the thiousulfate solution.

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: A process for treating a first metal, manganese-containing ore comprising contacting the manganese-containing ore with an aqueous, acidic composition and a material containing at least one metal sulfide at conditions effective to (1) chemically reduce at least a portion of the manganese, (2) solubilize at least a portion of the metal from the metal sulfide, and (3) at least partially liberate the first metal from the ore; and recovering the first metal from the ore. The use of Thiobacillus ferrooxidans and/or added ferric ion in the contacting step are also disclosed.

Abstract: A process for recovering at least one first metal from a metal sulfide-containing ore comprising contacting the ore with an aqueous, acidic composition and at least one reducible manganese-containing material at conditions effective (1) to chemically reduce the manganese, (2) solubilize at least a portion of the metal from the sulfide, and (3) at least partially liberate the first metal from the ore; and recovering the first metal from the ore. The use of added ferric ion and/or Thiobacillus ferrooxidans bacteria in the above-noted contacting is also disclosed.

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 process for the recovery of precious metals from ore containing the same is disclosed. The process includes the formation of a lixiviant solution including a thiourea compound, urea and an alkali lignin sulfonate. The ore is then exposed to this lixiviant solution to extract the previous metals therefrom, and the dissolved previous metals are then recovered from the solution.

Abstract: The purpose of the method is to remove chlorides and fluorides from a valuable metal raw material by leaching the raw material into sulphuric acid solution and by crystallizing the valuable metal sulphate selectively out of the solution. The valuable metal sulphate crystals are washed in sulphuric acid solution, and the recovered dechlorinated and defluorinated crystals are leached into water and conducted into electrolysis. The sulphuric acid solution employed in the raw material leaching and in the crystal washing is preferably the same as the return acid of the electrolysis. Chlorides and fluorides are removed from the mother liquor of crystallization in the bleed.

Abstract: This is a method for the complete leaching of the valuable metals in a metal sulphide material which contains copper, zinc, lead, silver and iron by the use of a solution which essentially contains cupric chloride/sulphates. After the valuable metals have been recovered, the solution is regenerated whereby ferrous chloride and cuprous chloride/sulphate is oxidized to a ferric hydroxide solid and a cupric chloride solution respectively. The regenerated solution is split into two part-solutions and returned to the process.One part-solution goes to a metathesis stage where the fresh metal sulphide material is added in large excess with respect to the part-solutions's content of copper. The result is that only the valuable metals like zinc, lead and silver are leached while copper and iron remain in the residue.The other part-solution goes to a leach stage where the residue from the metathesis stage is added.

Abstract: A process for the recovery of gold from a precious metal bearing sludge concentrate is disclosed. The process comprises the steps of leaching the sludge with hydrochloric acid and hydrogen peroxide to solubilize at least gold, palladium and platinum, removing silver from the leach slurry as insoluble silver chloride and selectively precipitating gold from the leach solution remaining after removal of silver by reduction with SO.sub.2 in the presence of sodium ions.

Abstract: This invention provides processes for selectively recovering silver and gold values from feed materials containing both precious metals, and comprises leaching the feed material with a hot ferric chloride-acid brine leach solution for a time sufficient to dissolve the silver, but wherein the gold is not dissolved and remains with the solid residue. The silver-containing ferric chloride-acid brine leachate is separated from the solid residue containing the gold. The leach solution is then cooled to precipitate the silver as silver chloride. The solid residue containing the gold is then leached with hypochlorous acid to dissolve the gold, and after separating the solids form the gold-containing hypochlorous acid leach solution, the gold is precipitated by contacting the solution with sulfur dioxide. The silver chloride may be further processed in a fused salt electrolysis step at or above the melting point of silver to produce a substantially pure silver and chlorine gas.

Abstract: A process for the recovery of precious metals from ore containing the same is disclosed. The process includes the formation of a lixiviant solution including a thiourea compound, urea and potassium lignin sulfonate. The ore is then exposed to this lixiviant solution to extract the precious metals therefrom, and the dissolved precious metals are then recovered from the solution.

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 the treatment of a complex manganese ore, wherein it comprises the following stages:(a) crushing the ore,(b) subdividing the crushed ore into a first part and a second part,(c) preparing the first pulp from the first part of the crushed ore,(d) reacting the first pulp with a reducing agent to obtain a manganous sulphate solution,(e) separating the liquid phase constituted by the thus obtained manganous sulphate solution from the solid phase of the thus treated first pulp,(f) preparing a second pulp from the second part of the crushed ore,(g) subjecting the second pulp to a solubilization treatment of the nickel, copper and cobalt by reacting it hot with sulphuric acid and the manganous sulphate solution obtained in stage (e),(h) separating the liquid phase and the solid phase of the thus treated second pulp, and(i) recovering the nickel, copper and cobalt from the liquid phase separated in stage (h).

Abstract: This invention relates to the development of a viable metallurgical process capable of treating low grade concentrates, bulk concentrates, dirty concentrates, or ore directly for the recovery of non-ferrous metals such as zinc, lead, copper, and precious metals and accordingly is significant to the development of massive fine grained sulphide ore bodies found throughout the world. The process involves the consecutive steps of sulphatizing roasting in a fluidized bed reactor, a two stage leach, metal recovery from solution by conventional processes such as electrowinning and precipitation, and recycling of residue wash waters and leach liquors containing high concentrations of iron and minor impurity elements to the roaster or a spray dryer for thermal decomposition. Simple and efficient rejection of iron from the circuit to residue as stable hematite is the net result of the recirculation and thermal decomposition.

Abstract: A hydrometallurgical process is provided for separating heavy metal nuisance elements such as As, Sb, Bi, Sn and Pb from precious metals and/or selenium. The process can be used as a step in an overall hydrometallurgical process for treating refinery residues such as anode slimes for the separation and recovery of valuable metal values.

Abstract: A novel gold purification method is provided which comprises electrolyzing gold into a novel pregnant electrolyte, segregating the dissolved gold ions from the cathode by a semipermeable barrier, separating insoluble impurities from the gold-containing liquidus, and then selectively reducing the gold to metallic form from the liquidus by a selective chemical reducing agent. The electrolyte is impregnated with a catalyst for leveling the overvoltage of gold and preferably contains a peroxide or a nascent oxygen source. A unitary apparatus for the method is provided.

Abstract: The invention comprises the treatment of metal oxides and mixed metal oxides and metal sulfides in a vertical tube reactor system having a downcomer section and a riser section in order to oxidize and dissolve the metal values in aqueous slurry primarily in the downcomer section and introducing a reducing agent comprising a formate species and reducing the dissolved metal values in the riser section. The reduced metal values are then separated with the gangue values from the product solution downstream from the vertical tube reactor system. The reduced metal values may then be separated from the gangue material by conventional solid separation techniques, such as flotation.

Abstract: A method of recovering copper and nickel from sulphidic minerals containing copper, nickel and iron comprises the steps of roasting the mineral, preferably to provide magnetite; sulphating, for example with sulphuric acid, sulphur trioxide, metal sulphate and/or sulphur dioxide together with oxygen; and a subsequent leaching of the sulphated material and recovery of copper from the leaching solution, for example by electrolysis. All or part of the leaching solution with its nickel content is recycled to the roasting stage, and the nickel content is removed in the form of nickel oxide together with the leaching residue, from which nickel can be recovered.

Abstract: A process for separating precious metals from a roaster calcine leach residue from a process wherein copper or zinc sulfides are roasted to produce a copper or zinc calcine; the calcine is leached with an aqueous sulfuric acid leaching solution to produce a copper or zinc-containing leaching solution and a roaster calcine leach residue and the copper or zinc-containing leaching solution is separated from the roaster calcine leach residue wherein the process comprises:(a) intimately contacting the roaster calcine leach residue with an aqueous sulfuric acid leach solution containing from about 5 to about 200 grams per liter of sulfuric acid to produce a slurry of leach solution and roaster calcine leach residue and to dissolve precious metal from roaster calcine leach residue;(b) adding copper or zinc sulfide solids to the mixture of leach solution and said roaster calcine each residue;(c) agitating the copper or zinc sulfide solids in intimate contact with the mixture of leach solution and roaster calcine leac

Abstract: A process for recovering gold from refractory auriferous iron-containing sulphidic ore which comprises feeding ground ore as an aqueous slurry to an acidic pretreatment step. The ground ore in the acidic pretreatment step is treated with aqueous sulphuric acid solution to decompose carbonate and acid consuming gangue compounds, and subjecting the treated slurry to a first liquid-solids separation step to produce a sulphate solution and separated solids. Water is added to the separated solids in a first repulping step to form a slurry having a pulp density in the range of from about 25 to about 60% by weight solids. The first repulped slurry is oxidized in a pressure oxidation step at a temperature in the range of from about 135.degree. to about 250.degree. C.

Abstract: A process for leaching copper from copper sulphide containing ore, in particular copper from chalcopyrite containing ore, is provided. The ore is preferably initially ground up and mixed with an aqueous acid leaching medium containing sulphide oxidizing bacteria, and a bacterial nutrient, and a catalytic amount of silver. Provision is made in the bacterial nutrient for a source of carbon dioxide and oxygen for the bacteria, both of which may be supplied by means of sparging with carbon dioxide enriched air. A bacterial compatible acid is added initially to the ore and leaching medium mixture and periodically during the process so that sulphide in the copper sulphide is oxidized in stoichiometric amounts to elemental sulphur. During leaching the oxidation potential is maintained between about 0.54 to 0.66 volts, most readily by initial addition of thiosulphate and dissolved copper.

Abstract: A process for separately recovering platinum group metal values, nickel values and copper from nickel-copper-iron sulphidic matte containing platinum group metals includes leaching ground matte at atmospheric pressure in acidic nickel-copper sulphate solution at a temperature in the range of from about 75.degree. to about 105.degree. C. and at a pH below about 4 initially under oxidizing conditions and subsequently under neutral or non-oxidizing conditions to cause dissolution of nickel and iron, precipitation of copper as a copper sulphide and precipitation of dissolved platinum group metals. The copper, nickel and platinum group metal containing solids are separated from the nickel and iron containing sulphate solution and are leached in acidic nickel-copper sulphate solution under pressurized oxidizing conditions at a temperature of from about 120.degree. to about 180.degree. C. to cause dissolution of nickel and copper with minor dissolution of platinum group metals.

Abstract: A process for recovering gold from refractory auriferous iron-containing concentrate includes feeding the concentrate as an aqueous slurry to an acidic pretreatment step and treating the concentrate in the acidic pretreatment step with aqueous sulphuric acid solution to decompose carbonate and other acid consuming gangue compounds. The treated slurry is oxidized in a pressure oxidation step at a temperature in the range of from about 135.degree. to about 250.degree. C. under a pressurized oxidizing atmosphere while maintaining a free acid concentration of from about 5 to about 40 g/L sulphuric acid to cause dissolution of iron, formation of sulphuric acid and oxidation of substantially all oxidizable sulphide compounds to sulphate form with less than about 20% of oxidized sulphur being present as elemental sulphur during the oxidation step.

Abstract: A process for separately recovering zinc and lead values from zinc and lead containing sulphidic ore which also contains iron comprises subjecting ground ore to a first flotation step to float an initial lead concentrate containing zinc and produce zinc and iron containing tailings. The zinc and iron containing tailings are subjected to a second flotation step to float an initial zinc concentrate containing iron and also produce tailings. The initial zinc concentrate is subjected to a third flotation step to float a further zinc concentrate containing iron and also produce zinc and iron containing tailings. The zinc and iron containing tailings from the third flotation step and at least a lead and zinc containing portion of the initial lead concentrate are leached in a first leach step under oxidizing conditions at a temperature in the range of from about 130.degree. to about 170.degree. C.

Abstract: The extent of recovery of precious metals, preferably gold and silver, from precious metal ores, concentrates, tailings and wastes which are also sulphide- and arsenic- and/or antimony-bearing, is enhanced by treatment with Caro's acid (H.sub.2 SO.sub.5).

Abstract: Process for treating oxidized ores with a manganiferous matrix to recover the small quantities of copper, nickel and cobalt, which consists of attacking the aforementioned ore by means of an aqueous solution of H.sub.2 SO.sub.4 with the simultaneous injection of sulfur dioxide, at a temperature which does not exceed boiling point of the medium, at a pH less than 1.5; introducing an alkaline sulfide to precipitate the copper, nickel and cobalt sulfides in the suspension resulting from the attack; and separating by sulfides and the residue by flotation. The process is applicable to attacks on manganiferous nodules obtained from ocean beds as well as to attacks on land manganiferous matrix oxidized ores.

Abstract: A process for recovering zinc from zinc-containing sulphidic material which also contains iron and lead includes leaching the material under oxidizing conditions at a temperature in the range of from about 130.degree. to about 155.degree. C. in aqueous sulphuric acid solution with a stoichiometric excess of sulphuric acid relative to the zinc content of the material of from about 50 to about 100% to produce an undissolved residue containing a major proportion of the lead and a leach solution containing a major proportion of the zinc and iron. The sulphur and lead containing residue is separated from the zinc and iron containing leach solution. Elemental sulphur is physically separated from the remaining lead-containing residue, and the remaining lead-containing residue is recovered. The zinc and iron containing leach solution is treated to recover zinc by feeding the solution to another process in which zinc-containing material is treated to recover zinc and which includes an iron-precipitation step.

Abstract: Zinc is separated from a zinc-copper alloy, in particular, brass scrap, by reacting the alloy with an aqueous alkali metal bisulfate to dissolve zinc selectively with respect to copper. Zinc is recovered from the resulting solution by precipitation in the form of an insoluble zinc compound, namely, zinc carbonate or zinc hydroxide.

Abstract: A process for recovering zinc from zinc-containing sulphidic material also containing iron and from zinc oxide containing material. Zinc-containing sulphidic material is leached under oxidizing conditions at a temperature in the range of from about 130.degree. to about 170.degree. C. in aqueous sulphuric acid solution with an initial stoichiometric excess of sulphuric acid relative to the zinc content of the sulphidic material to form a leach slurry containing dissolved zinc and iron. The leach step is continued until a substantial amount of zinc has been dissolved from the sulphidic material. Zinc oxide containing material is then added to the leach slurry to raise the pH of the slurry to a value in the range of from about 4.5 to about 5.5 to precipitate dissolved iron and form an iron-containing residue and a relatively iron-free leach solution. The residue is separated from the leach solution, and the leach solution is treated to recover zinc.

Abstract: A process for recovering metallic values by putting the values into solution and separating undesired mineral matter from the solution using countercurrent flotation is provided. The process involves leaching metallic values from host rock, conditioning the resultant ore pulp with the required reagents to achieve selective flotation of mineral matter in the metallic values solution, introducing the conditioned ore pulp into flotation cells, along with counterflow of solution from an immediately subsequent flotation step, wherein simultaneous washing and flotation is achieved, and the mineral matter is removed leaving a solution of the metallic values. The resultant mineral matter froth product is subjected to subsequent stages of flotation and simultaneous washing with counterflow of solution removed from each subsequent stage of flotation, water and/or barren solution being used for washing in the final flotation stage.

Abstract: Metal values are recovered from ore concentrates by forming a sulfide matte, grindng the matte, leaching with sulfuric acid at elevated temperature to selectively extract nickel and iron, and roasting and leaching the residue with dilute sulfuric acid to selectively extract copper. The residue contains a high concentration of platinum, palladium and gold.

Abstract: A process for recovering zinc from zinc containing sulphidic material which also contains iron together with lead and/or silver includes leaching the material under oxidizing conditions at a temperature in the range of from about 130.degree. to about 170.degree. C. in aqueous sulphuric acid solution with a stoichiometric excess of sulphuric acid relative to the zinc content of the material of from about 40 to about 100% to produce an undissolved residue containing a major proportion of lead and/or silver and a leach solution containing a major proportion of the zinc and iron. The residue is separated from the leach solution and treated to recover lead and/or silver values. The leach solution is treated to recover zinc by feeding the solution to another process in which zinc-containing material is treated to recover zinc and which includes an iron-precipitation step.

Abstract: A method of treating sulphidic mattes containing from 5% to 60% iron; from 15% to 40% sulphur together with soluble non-ferrous metals such as copper, cobalt, nickel and zinc and also optionally insoluble non-ferrous metals which term includes platinum group metals gold and silver by a leaching process to effect substantial separation of the non-ferrous metals from iron as well as from insoluble residue material. The matte is contacted in a finely subdivided form with sulphate in acid medium at a temperature of from 70.degree. C. to 120.degree. C. and an oxygen partial pressure of from 50kPa to 1,000kPa. The quantity of sulphate present is at least the stoichiometric amount required for dissolving the soluble non-ferrous metals present but is limited to ensure that a substantial proportion of iron which dissolves simultaneously with the soluble non-ferrous metals precipitates out as it is replaced by dissolving non-ferrous metals.

Abstract: Metal values are recovered from ore concentrates by forming a sulfide matte, grinding the matte, leaching with sulfuric acid at elevated temperature to selectively extract nickel and iron, and leaching the residue with an acidic aqueous ferric or cupric salt to selectively extract copper. The residue contains a high concentration of platinum, palladium and gold.

Abstract: The specification discloses a method for recovering non-ferrous metals such as zinc or copper iron from their concentrates, ores or any other metal containing materials into a solution containing these non-ferrous metals as sulphates and a minimal amount of dissolved iron. The resultant solution is suited without or with minimum pre-purification treatment for conventional electrowinning processes to recover such non-ferrous metals with less difficulties than the previous methods involving complex iron-removal processing. There is disclosed a method for recovering at least one non-ferrous metal soluble in sulphuric acid from a strong sulphuric acid solution containing said metal and iron as sulphates, said method comprising the following consecutive steps:subjecting said solution in a sub-divided form to thermal decomposition in a fluidized bed reactor at a temperature of from 600.degree. to 750.degree. C.

Abstract: This invention relates to environmentally sound hydrometallurgical methods and processes for extraction of cobalt, nickel and silver from complex concentrates. The finely ground minerals are converted during an oxidative caustic leach at elevated pressures and temperatures to insoluble metal hydroxides and are separated from soluble sodium arsenate and sodium sulphate. Cobalt and nickel are extracted from the caustic cake during a two-stage sulphuric acid leach. Solution purification for cobalt and nickel recovery proceeds on the basis that only one waste residue and one liquid effluent are generated which meet strict environmental standards. A small amount of cyanidation residue is generated after silver extraction by cyanidation from the acid leach residue. Metal values extraction reaches +99.0%. Arsenic and sulphur can be recovered in an innovative recycle system as sodium, zinc or copper arsenate chemicals and as anhydrous sodium sulphate.

Abstract: A method of recovering gold from anode slimes resulting from electrolytic copper refining comprises treating the anode slimes to remove copper and selenium, forming an aqueous slurry from the treated slimes, blowing chlorine gas into the aqueous slurry to dissolve the gold therein, and separating the so-dissolved gold from the residue.

Abstract: Zinc, copper and cadmium are recovered from their ferrites by subjecting the ferrites to a sulfuric acid bearing solution in the presence of potassium, sodium or ammonium ions under atmospheric conditions at 80.degree.-105.degree. C. to precipitate the iron present in the ferrites as jarosite, separating at least a portion of the jarosite-bearing solid material from the solution before recycling the solution to a neutral leach, from which a copper and cadmium bearing solution is recovered and to which acid and calcine are also fed, feeding the solid obtained from the neutral leach to the said ferrite treatment stage classifying the solid obtained from the neutral leach into a finer and coarser fraction, feeding the finer fraction to the ferrite treatment stage, comminuting the coarser fraction by grinding, leaching or milling and recycling the comminuted fraction to the process.

Abstract: A hydrometallurgical process for the treatment of a raw material which contains oxides and ferrites of zinc, copper and cadmium is disclosed, wherein the raw material is neutral leached by means of a sulfuric-acid-bearing solution to leach the oxides without substantial dissolving of the ferrites, a ferrite-bearing residue is separated, and a sulfuric-acid-bearing or ferrisulfate-bearing solution is mixed with the residue in order to leach the ferrite and to precipitate the iron in the form of jarosite in the presence of alkali or ammonium ions under atmospheric conditions at 80.degree.-105.degree. C., and the solid phase is separated from the solution.

Abstract: A process for the treatment of a raw material which contains oxides and ferrites of zinc, copper and cadmium is disclosed, in which the raw material is neutral leached with a sulfuric-acid-bearing solution in order to leach the oxide without substantial dissolving of ferrite, the ferrite-bearing residue is separated, and a sulfuric-acid-bearing or ferrisulfate-bearing solution is mixed with the residue in order to leach the ferrite and to precipitate the iron as jarosite in the presence of alkali ions or ammonium ions under atmospheric conditions at 80.degree.-105.degree. C., the sulfuric-acid-bearing or ferrisulfate-bearing solution being added to the ferrite-bearing residue in such an amount that approximately 50-60% of the ferrite dissolves and its iron precipitates as jarosite, the solid phase is dried and heated to so high a temperature that the zinc of the solid phase is converted to zinc sulfate and its iron to hematite according to the following reaction:(8) 3ZnFe.sub.2 O.sub.4(s) +2A[Fe.sub.3 (SO.

Abstract: The present invention relates to a process for the recovery of gold and/or silver and possibly bismuth contained in sulfuretted ores and/or sulfoarsenides, wherein said ores, after having been subjected to a reducing roasting, then to an oxidizing roasting then a possible crushing, are treated by a first lixiviation with sulfuric acid followed by a lixiviation with thiourea under precise conditions of operation.

Abstract: A method is provided for recovering copper values from a copper-bearing hematite residue in a single stage. It comprises leaching the residue in an aqueous sulphuric acid solution in the presence of ammonium, sodium or potassium ions, at a temperature between about 80.degree. C. and the boiling point of the solution so that copper values are dissolved while iron is precipitated as jarosite. The method is particularly suitable for the treatment of residues resulting from an oxidizing pressure leach of copper concentrates.

Abstract: Metal values are recovered from ore concentrates by means of dry grinding, followed by a two-stage leaching process in which the ground concentrate is first leached with sulfuric acid at a temperature of about 90.degree. to 100.degree. C. to selectively leach nickel and iron. The residue is then leached with a solution comprising sulfuric acid and NaOCl or H.sub.2 O.sub.2 to extract platinum, palladium, copper and gold.

Abstract: The specification discloses a method for recovering non-ferrous metals such as zinc or copper from their concentrates, ores or any other metal containing materials into a solution containing these non-ferrous metals as sulphates and a minimal amount of dissolved iron. The resultant solution is suited without or with minimum pre-purification treatment for conventional electrowinning processes to recover such non-ferrous metals with less difficulties than the previous methods involving complex iron-removal processing. There is disclosed a method for recovering at least one non-ferrous metal soluble in sulphuric acid from a strong sulphuric acid solution containing said metal and iron as sulphates, said method comprising the following consecutive steps:subjecting said solution in a sub-divided form to thermal decomposition in a fluidized bed reactor at a temperature of from 600.degree. to 750.degree. C.

Abstract: A process for separating selenium and tellurium values from each other by heating a solution containing both to a temperature and for a time period, in the presence of concentrated sulfuric acid under substantially anhydrous conditions, sufficient to precipitate the tellurium values. The process is primarily applied to decopperized copper anode slimes by first leaching such slimes with concentrated sulfuric acid under the specified conditions, separating the liquid and solids phases, and then removing the tellurium from the solids phase by a water leach.

Abstract: A process for separating metal values from sea nodules by sulfating the nodule ore under substantially dry conditions, followed by leaching of the sulfated ore; separation of the leaching solution from water-insoluble residue and recovery of the metal values from the leaching solution.