Abstract: A method for preparing manganese sulfate monohydrate by desulfurizing fume with middle-low grade manganese dioxide ore, which includes: preparing a slurry by using middle-low grade manganese dioxide ore powder, putting sulfur-containing fume in an absorbing device and controlling gas velocity and gas-liquid ratio, and then adding manganese dioxide slurry and controlling the slurry to backwards flow relative to the sulfur-containing fume, discharging the desulfurized fume from the absorbing device, pressure-filtering and separating the slurry discharged from the absorbing device, recycling the mother liquor to the absorbing device, and continuing the recycling operation until the manganese sulfate in the mother liquor is >=200 g/l, the obtained filter cake at 60-70° C., adjusting pH value of the clear solution obtained to 2-4, adding manganese sulfide under agitation at 25-95° C.

Abstract: A process is provided for stabilizing a sulfate and/or sulfide-rich waste material, comprising metal sulfide minerals, and sequestering CO2 comprises exposing the material to a CO2-enriched gas mixture, reacting the CO2-enriched gas mixture with the metal sulfide minerals and forming a CO2-depleted gas mixture and a carbon-containing compound and at least one product selected from the group consisting of a purified metal or a metal-rich compound suitable for smelting or refining, sulfuric acid, sulfur and sulfurous acid, and system and apparatus therefor.

Abstract: The invention provides a process for producing purified synthesis gas from synthesis gas comprising sulphur contaminants in the ppmv range, the process comprising the step of: (a) contacting the synthesis gas comprising sulphur contaminants with solid sorbent comprising a metal organic framework, thereby separating sulphur contaminants from the synthesis gas to obtain purified synthesis gas.

Abstract: Provided is a method of easily producing easily-filterable and stable scorodite that meets the leaching standard (conformance to Japanese Environmental Agency Notice 13) with excellent reproducibility and without using complex operations, when processing arsenic that is included in non-ferrous smelting intermediates, and particularly when processing arsenic in the form of a sulfide. Scorodite is produced by a leaching step of leaching arsenic from a non-ferrous melting intermediate containing arsenic in the weakly acid region, a solution adjusting step of oxidizing trivalent arsenic to pentavalent arsenic by adding an oxidizing agent to the leaching solution, and a crystallizing step of converting the arsenic in the adjusted solution to scorodite crystals.

Abstract: A desulfurizer for fuel gas for a fuel cell includes: a first adsorption tank including an adsorber having selective adsorption capacity for a thiophene-based compound and a second adsorption tank including an adsorber having selective adsorption capacity for a mercaptan-based compound. The desulfurizer uses separate adsorbers having selective adsorption capacity for a thiophene-based compound and a mercaptan-based compound, in multiple stages to perform a more efficient and economical desulfurizing of a fuel gas to remove various sulfur compounds, especially thiophene-based compounds and mercaptan-based compounds compared to a desulfurizer using a single adsorber.

Abstract: The invention relates to nanometric or mesoscopic dissymmetric particles, and to a method for preparing the same. The particles have an inorganic part A and a spherical organic part B bound by physicochemical or covalent interactions. Material A is a metal oxide, a metal or a metal chalcogenide. Material B is a polymer consisting of recurrent units derived from a vinyl compound. The particles are obtained by modifying the surface of material A particles with a coupling agent C having a function FC which exhibits affinity for the polymer, and contacting the modified inorganic particles with the precursor(s) of the polymer B, in the presence of a free radical initiator and of a surfactant in solution in a solvent.

Abstract: A method of extracting gold from arsenic gold ore concentrate, wherein increase the temperature of smelting chamber to 100-300° C. and then hold the temperature to remove the vapor and small quantity of dust in the arsenic gold ore concentrate; Under residual pressure?50 Pa, increase the temperature of smelting chamber and crystallization chamber to 300-500° C. and then hold the temperature to remove the volatilized arsenic sulfides; Hold the temperature of crystallization chamber, increase the temperature of smelting chamber to 500-600° C. and then hold the temperature to remove the gaseous element sulfur decomposed; Increase the temperature of smelting chamber to 600-760° C. and then hold the temperature, lower the crystallization chamber temperature to 270-370° C. and then hold the temperature to get element arsenic; shutdown, lower the temperature, charge the air, take out the gold-rich slag after dearsenization, and extract fine gold using conventional method.

Abstract: A chemical process to leach copper concentrates in the presence of a concentrated solution of sulfates and chlorides. The process includes forming a high reactivity chemical paste containing a high concentration of ions in the liquid phase of the paste which react with copper ores and forms a series of soluble salts. The salts are extracted by a simple wash. Mixing equipment for handling high viscosity liquids is used. The total mixing time is about 5 minutes, after which the paste is poured into a rectangular mold, of several hundred meters per side, and is left to settle and breathe. During settling, water and sulfuric acid are added at intervals to replace that consumed by the reactions taking place during the aeration, until the reactions have virtually end. This treatment results in a dry, very resistant mass, containing the copper extracted in form of chlorine salts, and sulfate.

Abstract: Particulate material to be calcined is conditioned and then introduced into a stream of flue gases which transport the material along a sloping drying duct while drying the material. The dried material is then introduced into the same stream of flue gases upstream of the drying duct, and the flue gases transport the dried material along a sloping preheating duct while preheating the material. The preheated material is fed tangentially into the lower end of a vertical calcine reactor and calcined product is withdrawn tangentially from the upper end of the reactor. The flue gases used for drying and preheating are produced in the calcine reactor and are cooled during the drying and preheating.

Abstract: A key-operating device includes a shell confining a chamber therein and connected to a video game apparatus with depressible keys, a lever pivotally mounted in the chamber and having protrusions projecting toward the keys, a wheel surrounding and connected to the shell and rotatable relative to the shell, and an actuating member projecting from the wheel and engageable with the lever in such a manner that rotation of the wheel results in engagement between the actuating member and the lever so as to permit fulcrum movement of the lever and pressing of the keys by the protrusions.

Abstract: A Process for the treatment or removal of impurities, such as arsenic, antimony or bismuth, generated as by-products during smelting and refining of copper concentrates, comprises subjecting the by-products to pressure oxidation along with a copper concentrate in a hydrometallurgical copper extraction process or the treatment of impurities when present in a concentrate by subjecting the concentrate to a hydrometallurgical extraction process.

Abstract: Roasting of ores with metal values such as precious metal ores for recovery of metal values with conversion of arsenic to an insoluble form in-situ in presence of an additive such as iron and in presence of oxygen injected initially or supplementally in a roaster such as in a circulating fluid bed roaster; volatilized arsenic in roasting of ores may also be converted to an insoluble form in gas phase in a two stage roaster process after removal of solids from a gas phase and contact with an additive at high oxygen concentration in a second stage roaster.

Abstract: The present invention provides a process for treating a particulate material, in which particles of the material to be treated interact with non-static particles of a second material, the process comprising the steps of: (i) providing a processing chamber (1) having an inlet (7) and an outlet (10) spaced downstream therefrom, the base (15) of said chamber comprising a plurality of outwardly radiating inclined vanes (20, 25), (ii) providing a host bed of particles (30) which include inert particles, alumina, limestone and activated carbon in the chamber (1) and generating a flow of fluid through the vanes (20, 25) at the base (15) of the processing chamber such that the bed of host particles (30) circulates about an axis of the chamber in a compact band, (iii) injecting particles of the material to be treated including sulphide ore, kaolin, gypsum and talc through an inlet (5) of the chamber (1) to contact with the circulating bed of the host particles (30), wherein the relative terminal velocity of the partic

Abstract: Briefly stated, there is provided a method for reducing cyanide consumption in precious metals mining extraction processes involving a sulfur bearing ore body, comprising the steps of providing a precious metal bearing material having intermediate sulfur oxidation products, and exposing the material to sulfur dioxide gas, bisulfite ions or sulfite ions, in a manner to cause at least a portion of the intermediate sulfur oxidation products to be rendered unreactive with cyanide.

Abstract: A process for removing impurities contained in the crystal lattice of minerals, comprising the steps of forming a mixture of a mineral capable of structurally reorganizing its crystal lattice which contains an impurity in its crystal lattice and a halogen anion, and water; heating the mixture to the mineral's structural reorganization transition temperature; holding the mixture at the structural reorganization transition temperature for a sufficient period of time to allow the impurity to freely migrate from the lattice to combine with the halogen anion; and separating the combined impurity and anion from the mixture to render the mineral essentially free of the impurity. The process is applicable to numerous minerals and impurities, but is especially useful to remove arsenic from fluorspar. Numerous halogen anions can be employed, such as chlorides, fluorides, bromides and iodides, but the preferred halogen anion is a metal chloride such as calcium chloride.

Abstract: The invention is concerned with an improved process for the desulphurization of blister copper during anode refining, wherein a mixture of an inert gas and an oxygen containing gas is blown into liquid blister copper. The improvement resides in varying the amount of oxygen containing gas in the mixture of nitrogen and oxygen during the desulphurization of blister copper. The process of the invention enables one to increase the recovery of copper, decrease the recycling of highly oxidized slag, decrease the time of desulphurization, decrease refractory wear, decrease subsequent time of reduction and decrease the amounts of reactants used.

Abstract: An ore separation process is provided which begins with a specially designed primary grinding mill. The primary grinding mill grinds the ore into a fine powder which is then blown into the primary sizing baghouse which separates the smaller particles from the larger particles. The oversized particles are channeled to the secondary grinding mill where they are ground again and blown to the secondary sizing baghouse. The grinding process is repeated until all the ore is the proper size. Once the ore has been ground to the proper size it is sent to the ore-roasting oven where it is mixed with a precise amount of air where it is flash heated which initiates the process of separating the values from the wastes. From the ore-roasting oven, the heated ore is channeled to the quench chambers where it is cooled very quickly which results in the breaking up of the ore into its constituent components.

Abstract: This invention provides a method to control the off gas emission of sulfur dioxide from a mineral ore roaster by grinding a sulfur-containing mineral ore, adding sodium sesquicarbonate to the mineral ore, and roasting the ore and sodium sesquicarbonate at an elevated temperature.

Abstract: Refractory gold ores are roasted in the presence of added fuels in an oxidizing atmosphere in a fluidized bed at a temperature from 450 to 650° C., which is supplied with oxygen-containing gases; to achieve a low ignition and thus low roasting temperature, sulfur, pyrite or mixtures thereof are used as added fuels.

Abstract: A method of treating a mined material which includes a sulphide mineral and iron or a concentrate of the mined material to improve the recovery of a valuable metal from the sulphide mineral is disclosed. The method comprises: (i) oxidising the sulphide mineral in the presence of ferric ions to make the valuable metal in the sulphide mineral more accessible to extraction; and (ii) oxidising ferrous ions generated in step (i) or derived from iron in the mined material with a mixture of sulphur dioxide and oxygen to produce ferric ions for step (i).

Abstract: A process for removing impurities contained in the crystal lattice of minerals, comprising the steps of forming a mixture of a mineral capable of structurally reorganizing its crystal lattice which contains an impurity in its crystal lattice and a halogen anion, and water; heating the mixture to the mineral's structural reorganization transition temperature; holding the mixture at the structural reorganization transition temperature for a sufficient period of time to allow the impurity to freely migrate from the lattice to combine with the halogen anion; and separating the combined impurity and anion from the mixture to render the mineral essentially free of the impurity. The process is applicable to numerous minerals and impurities, but is especially useful to remove arsenic from fluorspar. Numerous halogen anions can be employed, such as chlorides, fluorides, bromides and iodides, but the preferred halogen anion is a metal chloride such as calcium chloride.

Abstract: The ore which contains gold and at least one of the metals silver, copper, nickel, zinc or iron is calcined at temperatures in the range from 500.degree. to 900.degree. C. with the addition of oxygen-containing gas, thereby producing a metal-oxide-containing solids mixture and a SO.sub.2 -containing exhaust gas. The SO.sub.2 containing exhaust gas is brought in contact with aqueous solution, thereby producing a sulfite-containing solution. The solids mixture from the calcination is cooled to temperatures in the range from 50.degree. to 300.degree. C. and is stirred up with the sulfite-containing solution. Metal oxides are dissolved, and a sulfate-containing solution os formed. In a first separating zone, the sulfate-containing solution is separated from the solids, and either the solids are supplied to a gold leaching or the sulfate-containing solution is subjected to a further treatment for the separation of nonferrous metals.

Abstract: The ore which contains gold and/or silver and as accompanying metal at least iron is calcined at temperatures in the range from 500.degree. to 900.degree. C. with the addition of oxygen-containing gas. There is obtained a metal-oxide-containing solids mixture and a SO.sub.2 -containing exhaust gas. The solids mixture from the calcination is cooled, the temperature being reduced by at least 50.degree. C. The cooled solids mixture is added to a fluidized-bed reactor, and SO.sub.2 -containing exhaust gas is introduced into the fluidized-bed reactor. In the reactor, metal sulfate is produced in the solids mixture, so that at least 10% of the sulfur content are bound in the exhaust gas. Solids mixture containing metal sulfate is withdrawn from the fluidized-bed reactor, is stirred up with an aqueous acid solution, thereby dissolving metal sulfate. The remaining solids are supplied to a recovery of gold and/or silver.

Abstract: Refractory gold ores are roasted at temperatures from 500.degree. to 650.degree. C. in an oxidizing atmosphere in a fluidized bed, which is supplied with a carbonaceous additional fuel. To effect a substantially complete combustion of the additional fuel to form CO.sub.2 and H.sub.2 O, methanol is added as a carbonaceous fuel.

Abstract: The present invention relates to a process for roasting gold containing ore in which a flash furnace means is provided, in particular a gas suspension furnace for roasting the ore. Hot gas and the gold containing ore to be roasted are supplied to the furnace means, wherein the hot gas roasts the ore within the furnace means at temperatures between about 500.degree. C. and 700.degree. C. while the ore is suspended in the hot gas, after which the roasted ore is discharged from the furnace means along with the hot gas. In the apparatus of the present the ore to be calcined may optionally be preheated, prior to the ore entering the furnace means, by suspending the fresh ore in hot gas.

Abstract: In the process of removing heavy metals from aqueous solutions by precipitation of a salt thereof at increased pH, multiple stage precipitation by upward stepwise pH adjustment and solid separation at each stage is used to facilitate the manufacture of a product of high purity.

Abstract: A method for roasting sulphide ores or ore concentrates containing precious metals is practiced in a furnace, typically in a fluidized bed. The ore and a sulphur-binding lime-containing material are supplied to a roasting furnace in which the ore is roasted with the emission of heat and sulphur dioxide. The lime-containing material--such as calcium hydroxide--is mixed into the cooling water for the roasting furnace and sprayed into the furnace as a lime-containing aqueous slurry. Roasting occurs at about 600-850.degree. C. (e.g. 650-750.degree. C.).Roasted material is discharged from the furnace and acted upon to recover gold, silver and copper metal.

Abstract: Methods are disclosed for treating smelter flue dust and other smelter by-products so as to recover non-ferrous metals therefrom and convert arsenic and sulfur in the flue dust into non-leachable compounds. The methods allow the flue dust and other smelter by-products such as smelter sludges to be disposed of in a natural environment without subsequent leaching of heavy metals, sulfur, and arsenic. The smelter by-products are mixed with hydrated lie, formed into agglomerates, and roasted at an optimal temperature of about 650.degree. C. to form oxidized arsenic and sulfur which react with the lime in the agglomerates to form non-leachable compounds. The roasted agglomerates are contacted with a basic lixiviant comprising dissolved ammonia and an ammonium salt to dissolve non-ferrous metals such as copper from the roasted agglomerates. Used lixiviant can be boiled to precipitate the non-ferrous metals dissolved therein and vaporize the ammonia, thereby regenerating the lixiviant.

Abstract: A process for recovery of metal from a feedstock comprising copper is provided. The process comprises the steps of:(a) contacting the feedstock with an aqueous mixture comprising ammonium nitrate having a concentration greater than about 1.5M and sulphuric acid having a concentration greater than about 6M at a temperature of from about 105.degree. C. to about 130.degree. C., to produce a first residue comprising a cuprous salt and a leachate comprising copper;(b) separating the residue from the leachate; and(c) electrowinning copper from the leachate.The process may also be used advantageously to recover iron present in the feedstock in a form other than jarosite.

Abstract: A method to operate a flash calcination unit with both atmosphere and temperature control is described for mineral processing requirements and other atmosphere controlled processes. The method can be used to process phosphate, gold ore or activated carbon. The critical steps of the method involve an initial mixing of fine material combined with stoichiometric burning using at least one staged combustion furnace in a vertically oriented suspension calcination furnace. This effects control of oxygen or atmosphere in the combustion furnace with attendant control of temperature in that furnace.

Abstract: The invention provides a method of forming copper arsenate. Copper and arsenic are leached into a treatment solution maintained at a pH level of about 2 to 5 in the presence of at least one impurity. An oxidant is added to the treatment solution to oxidize the copper and arsenic. A copper arsenate compound is precipitated from the solution as copper arsenate. Preferably, the copper arsenate is then releached in a purification solution. The molar ratio of copper to arsenic is adjusted to a level of at least 2. The pH of the purification solution is then increased to precipitate copper arsenate having a decreased concentration of said at least one impurity. Impure copper arsenate may be suspended and reacted in a recrystallization solution preferably having cupric ion. The pH of recrystallization solution is adjusted to a valve between about 1 and 4.5.

Abstract: The invention is a process for the removal of high concentrations of impurities including antimony (Sb), bismuth (Bi), arsenic (As), lead (Pb), zinc (Zn), cadmium (Cd), selenium (Se) and tellurium (Te) contained in flue dusts produced during the smelting of copper. To effect the separation, the flue dust is slurried to about 10-30 weight percent solids. Then slurry is fed to gravity separation equipment, where the lighter impurities fraction segregates from the heavier revenue metals fraction. The segregated high copper concentrate is then washed while the tailings are neutralized by lime milk, dewatered and recovered as tailings cake. The wash solution together with the thickener overflow is subjected to copper cementation to recover the dissolved copper in the solution. The lighter impurities fraction can be subjected to acid leaching in order to further recover copper therefrom.

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: 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: Waste containing sulfur and nickel sulfide is heated to volatilize sulfur and reacted with hydrogen chloride to form nickel chloride.

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 of extracting metals from a material containing at least 10% by weight of pyrite and selected from the group consisting of ores containing sulphide, concentrates of such ores and mixtures of such ores and/or concentrates by microbial leaching which comprises roasting the material before the microbial leaching to convert part of the pyrite to pyrrhotite and thus remove part of the sulphur which is present as pyrite without the formation of any significant amount of metal oxide, the conversion corresponding to removal of at least 10% but not more than 50% of the sulphur present in the pyrite, and only thereafter leaching the thus roasted ore by treatment with bacteria, to extract the metals. The process is characterized by its improved efficiency in metal extraction.

Abstract: A method of treating pyrite bearing polymetallic material comprises heating the material in an atmosphere of reducing gases at a temperature of 450.degree. to 500.degree. C. for a period of 30 to 60 min.Gases such as hydrogen, or products of conversion of natural gas or mazut can be used to provide the reducing atmosphere.The roasted copper-containing material is cooled at a rate of 2 to 4 deg. per min and is then subjected to magnetic separation.The operation of magnetic separation is carried out in two stages with the intensity of the magnetic field ranging from 1000 to 2000 oersted, whereafter copper sulphides are removed from the roast, with a magnetic field intensity ranging from 4500 to 6000 oersted.

Abstract: A process for removing sulfur from sulfide-bearing ores by reacting water vapor with the sulfide-bearing ore forming hydrogen sulfide while simultaneously regenerating water vapor by reacting the hydrogen sulfide with lime. Advantageously, the process occurs in the absence of a net consumption or production of gaseous species so that the process can be carried out in a closed system with respect to the gaseous species. Sulfide-bearing ores which can be treated using the process of this invention include sulfide-bearing ores of molybdenum, zinc, iron, mercury, and copper. Advantageously, the molybdenum oxide so produced from the sulfide-bearing ore of molybdenum can be reacted further with lime and water producing calcium molybdate and hydrogen. The chalcopyrite form of the sulfide-bearing ore of copper produces bornite and magnetite.

Abstract: A method comprises heating the material to be treated without access of air at a temperature of 700.degree. to 800.degree. C. for a period of 1-2 hours, and then subjecting this material to subsequent magnetic separation.It is advisable that the furnace walls surrounding the material under treatment be heated to a temperature which is 100.degree. C. to 200.degree. C. higher than the boiling temperature of the volatile components of the material. Upon completion of the heating operation, the material being treated is cooled at a rate of 2 to 4 deg. per minute, whereafter iron sulphides are removed therefrom by means of magnetic separation, the intensity of magnetic field ranging from 1000 to 2000 oersted, and then copper sulphides are separated, with the field intensity ranging from 4500 to 6000 oersted.

Abstract: A process for the recovery of copper from its ores by conventional procedures requiring heat in which the source of heat is microwave energy. The microwave energy is used to selectively heat the copper compounds, such as sulfidic and oxidic compounds, in the ore, as respects the gangue, to convert the compounds into other compounds, such as oxides and chlorides, from which copper is more readily recoverable.

Abstract: A process is provided for leaching nickeliferous sulfide material, such as NiS precipitate and thermally activated nickel sulfide material, e.g., nickel matte, the process comprising subjecting nickeliferous sulfide material in the finely divided state to leaching in hydrochloric acid of concentration ranging from about 3 N to 8 N at a temperature of over 50.degree. C., the temperature and acid concentration being selected to dissolve at least about 50% by weight of the total contained nickel.

Abstract: This invention relates to method and apparatus for treating a sulfur containing material having at least one principal sulfide either in the form of a sulfide or in a form that is transformable into a sulfide and at least one auxiliary sulfide more volatile than the principal sulfide or transformable into another sulfide more volatile than the principal sulfide, wherein the sulfurous material is heated in one furnace zone, having a non-oxidizing atmosphere in the gas phase, to a temperature between that required for volatilization of the principal sulfide and that required for volatilization of the auxiliary sulfide to volatilize the auxiliary sulfide and labile sulfur, without volatilizing or substantially oxidizing the principal sulfide; and heating the sulfurous material in another furnace zone, having an oxidizing atmosphere in the gas phase, to a temperature lower than that required for substantial oxidization of the principal sulfide, to oxidize the volatilized labile sulfur and auxiliary sulfide, witho

Abstract: A method for desulphurizing fluid materials such as molten iron, steel, stack gases, synthetic natural gases, boiler gases, coal gasification and liquification products and the like is provided in which one of the group rare earth oxides, rare earth fluocarbonates, rare earth oxyfluorides and mixtures thereof, including bastnasite concentrates are reacted at low oxygen potential, with the sulphur to be removed to form one of the group consisting of rare earth sulphides, rare earth oxysulphides and mixtures thereof. The low oxygen potential can be achieved by carrying out the reaction in the presence of vacuum, reducing gases, carbon, etc.

Abstract: A process for thermal activation of chalcopyrite-pyrite ore concentrates for activation of iron values in both chalcopyrite and pyrite constituents whereby said iron values can be selectively removed in a subsequent acid leach. Controlled oxidizing conditions are maintained in an oxidizing heating zone for removal of up to about 90% of total sulfur to be removed for conversion of pyrite and chalcopyrite to their acid-leachable forms, measured by a preferable oxidation of 10 to 15% of iron in the concentrate to ferromagnetic oxides, whereby remaining total sulfur to be removed is removed in a reducing zone with the assistance of a low H.sub.2 S/(H.sub.2 +H.sub.2 S) ratio by scavenging of H.sub.2 S by said oxides.

Abstract: A copper-containing sulfidic material is dead-roasted at a temperature of at least 750.degree. C. and the resulting calcine is leached in a sulfuric acid solution to dissolve most of the copper in preference to any iron, nickel and cobalt in the material.

Abstract: Non-ferrous metal sulfides are converted to recover metals therefrom in a high speed rotary converter, wherein an oxygen-containing gas is used for said conversion, with sulfur trioxide added to the converter along with the oxygen-containing gas to assist in control of temperatures of the charge during conversion, the sulfur trioxide being reduced to sulfur dioxide within the converter and exhausted therefrom.

Abstract: A hydrometallurgical process for treating iron containing metal sulfides for rendering iron and non-ferrous metal values active and amenable for selective extraction and separate recovery. Sulfur values can be controllably produced as elemental sulfur or as sulfuric acid to supply acid requirements of the process, while substantially obviating the discharge of sulfur-containing gases to the atmosphere. Ores and concentrates of the sulfides are thermally activated by sequentially heating and reducing said sulfides in a countercurrent flow of heating and reducing gases respectively in a reactor whereby the reaction products of the reducing gas and sulfides, together with liberated labile sulfur, are controllably combusted with oxygen to satisfy heat requirements of the thermal activation process and to convert sulfur values to SO.sub.2 gas. The activated sulfides are subjected to an acid leach in aqueous sulfuric acid for production of ferrous sulfate and evolution of H.sub.