Abstract: A process is provided for hydrometallurgical processing of steel plant dusts containing cadmium, lead, zinc, and iron values, along with impurities such as chloride and fluoride salts of sodium, potassium, magnesium, etc. The first step in the process involves leaching the dust in a mixed sulfate-chloride medium that dissolves most of the zinc and cadmium. Any iron and aluminum dissolved in this step is precipitated by oxidation and neutralization. Zinc is recovered from the resulting solution by solvent extraction which provides a raffinate which is recycled to the leaching step with a bleed stream also provided for recovery of cadmium and removal of other impurities from the circuit. The lead sulfate residue from the leaching step is leached with caustic soda, and zinc dust is used to cement the lead out from the caustic solution, which then joins the main solution for zinc recovery.

Abstract: A process for the pressure oxidation leaching of non-ferrous metal sulphidic material which comprises providing an autoclave assembly which has a series of successive compartments, the first compartment of which being substantially larger in size than each of the remaining compartments. An oxygen partial pressure is provided in the autoclave assembly in the range of from about 50 to about 2000 kPa. An aqueous slurry of the material is fed into the relatively large first compartment with resultant flow of the material through the successive smaller compartments causing the temperature in the first and successive compartments to be sufficient to produce autogeneous oxidation of the sulphidic material. The oxidized slurry from the last compartment of the series is discharged.

Abstract: There is disclosed a novel method of recovering valuable metals from an industrial by-product containing copper and arsenic and at least one metal selected from among lead, zinc, iron, silver and cadmium, said method comprising leaching the by-product with sulfuric acid in an SO.sub.2 gas atmosphere at a temperature of 70.degree. C. or higher in the presence of a solid sulfide to thereby precipitate copper selectively as copper sulfide while dissolving other metal or metals in the leach solution and then separating the copper containing precipitate from the leach solution, said leach solution containing substantially no copper.

Abstract: The invention is concerned with a method for the selective dissolution of lead in relation to zinc that is present as a sulphurized compound.The method comprises treating said compound to lixiviation with a solution containing ferrous chloride, while bubbling a gas that contains oxygen through the lixiviating solution.

Abstract: A process for selectively leaching lead and silver chlorides from a sulfide ore residue in a rapid time which comprises brine leaching the residue under pressure at a temperature above the normal boiling point of the solution, preferably above 100.degree. C.Modifications are leaching at the agglomeration temperature of sulfur when present in the residue to agglomerate the sulfur for ease of recovery, and flashing from leach temperature to ambient as a lead chloride crystallization recovery step to produce a large crop of lead chloride crystals per pass.

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 present invention is directed to heap leach processes for leaching metal values from ore. The heap is constructed with a plurality of cellular heaps formed by loading ore onto an impermeable pad having a raised berm network thereon to separate the pad surface into a plurality of reservoirs. Leach solution percolating through the ore is collected in the respective reservoirs. Additional cellular heaps may be subsequently built overlying the original cellular heaps with an impermeable barrier being placed between stacked cellular heaps to prevent overleaching of underlying cellular heaps. The effluent leach solution from the overlying cellular heap is routed to the underlying reservoir from where it is withdrawn. Use of berms on the surface of the individual cellular heaps permits pooling of leach solution thereon for enhanced leaching. An earthen dam around the heap eliminates ore sides to the heap and insulates the heap during cold weather.

Abstract: A process for removing metal contaminants from a hydroconversion catalyst, said catalyst containing at least one metal from Groups VIB, VIIB or VIII supported on a refractory inorganic oxide. The process comprises contacting the contaminated catalyst with a buffered oxalic acid solution wherein contaminant is removed without dissolving the support.

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: 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: In the method the ground scraps are screened to separate the pole active material, i.e. Pb and PbO.sub.2, as fines. This active material is then reacted in the presence of a strong alkaline solution to yield a minium precipitate.Minium may be subsequently treated with an appropriate acid, such as fluoboric acid, freed of antimony by precipitating the latter with metal lead, and then subjected to electrolysis to recover lead.

Abstract: A process for separating inorganic substances involving their abstraction from a mixture with near-supercritical inorganic fluids. One or more inorganic substances are abstracted and then separatively recovered by retrograde condensations. The process particularly is applicable with mixtures obtained from the chlorination of metalliferous ores and may be conjoined to many ancillary metal abstraction processes such as volatilizations, distillations or electrolyses.

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 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: The invention provides a process for the selective dissolution of oxygenated compounds containing at least one non-ferrous metal selected from the group consisting of nickel, zinc, and copper, present in a mixture of oxygenated compounds containing said at least one non-ferrous metal and at least one element selected from the group consisting of lead, cobalt, iron, manganese, and silicon, and comprises suspending the mixture of the oxygenated metallic compounds in an aqueous phase which, preferably, contains chloride and alkaline earth metal ions; treating the resulting aqueous suspension, maintained at a pH exceeding about 1, with chlorine, preferably at a temperature ranging from about 60.degree. C. to the boiling point of the suspension, to selectively solubilize the said at least one non-ferrous metal while the said at least one element remains in an essentially insoluble residue; and separating the aqueous solution containing the dissolved said at least one non-ferrous metal from the insoluble residue.

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: Metal values, such as copper, lead and zinc, are recovered from complex sulfides, e.g., ores or smelter flue dusts, by means of aqueous leaching in the presence of oxygen and CaCl.sub.2 or BaCl.sub.2 at elevated temperature.

Abstract: A method of concentrating silver from anode slime which comprises reacting an intermediate product obtained by treatment of the slime, the intermediate product containing lead in sulfate form and silver in chloride form, with an aqueous solution of an alkali hydroxide or carbonate. The obtained reaction product is then subjected to solid-liquid separation, and the resulting residue is reacted with a nitric acid solution so that the lead therein may be separated into a filtrate, while the silver will remain in the residue.

Abstract: Residues containing lead as lead sulphate and silver in the form of native silver or silver chloride, sulfide or sulphate, as well as silver complexes with other metals, and resulting from the roasting and leaching of sulfide concentrates containing lead, zinc, copper, and silver are treated to produce a high grade lead and silver product containing lead predominantly as calcium plumbate in a process wherein the residue is leached with brine, the resultant leach solution treated with lime to precipitate lead as oxychlorides, and the resultant lime-oxychloride precipitate is calcined to produce a mixture of calcium orthoplumbate and lead oxide. Residual chloride can be washed easily from this product which may then be treated in a lead blast furnace to recover lead and associated silver in their elemental state.

Abstract: Uranium ore is crushed and formed into a slurry. The slurry is pumped into a leaching tank and classified by a sparge tube projecting water at teeter velocity at the bottom of the ore bed. Thereafter, a second ore bed is pumped by the slurry into the tank and the second bed classified. This is repeated until there are four or five ore beds in the tank.Thereafter, the ore is leached by passing liquid up from the bottom of the tank at velocities less than teeter velocities so that the bed remains classified.After leaching, the ore is formed into a slurry and the slurry pumped from the tanks to disposal.

Abstract: A process for the removal of lead content in anode slime by subjecting the latter to primary and secondary leach in a medium of an ammonium acetate solution at a temperature not exceeding 80.degree. C. Whereby lead dissolution is maximized and other metals are minimized. Separate the leach solution from the undissolved slime residue, crystallize lead from the separated leach solution and recover the crystallized lead acetate.

Abstract: A method of leaching of metal sulphide-containing material is disclosed. The metal sulphides can be iron, copper, lead, silver, mercury and/or zinc. The leaching is effected by means of chloride-containing solutions through red-ox reaction. The metal sulphide-containing material is reacted with a solution which consists chiefly of cupric chloride and ferric chloride.

Abstract: Process and apparatus for hydrometallurgical treatment of metallurgical dust by acid leaching followed by a solid-liquid separation. The invention is characterized in that the leaching phase is effected by moderate acid attack (pH at the end of the reaction about 4 or 5) and in which a supplementary solid-solid separation stage is provided, before the solid-liquid separation or after. The invention is applicable to all dusts resulting from treatment of metals, notably ironworking dusts, and particularly those formed in blast furnaces so as to permit the separation and recovery of useful elements contained therein, such as iron, zinc and lead.

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: Tin salts, such as, for example, alkali metal stannates, are produced by contacting at elevated temperatures an aqueous alkaline solution, such as for example, alkali metal hydroxide solutions, with a tin-containing material in the presence of a reaction promotor comprising the combination of activated carbon and an oxygen supplying agent.

Abstract: The invention provides a process for extracting zinc from a sulphur- and zinc-containing ore which involves (a) leaching the sulphur ore or concentrate with an aqueous solution of cupric chloride, which can be regenerated by means of a regenerating agent and air; (b) subjecting the solution thus obtained to liquid-liquid extraction by means of an organic phase, preferably containing a solvent, comprising an acid organophosphorus compound; and (c) recovering the zinc contained in the said organic phase after the said extraction, preferably by elution. If justified by the composition of the ore, the following optional recovery steps may then be performed:(1) if lead is present, recovery of lead by cementation (i.e., precipitation) or by crystallization of lead dichloride followed by cementation of the crystallizate;(2) if copper is present, recovery of copper by cementation or by liquid-liquid extraction; and(3) if precious metals, e.g.

Abstract: A hydrometallurgical process is used to recover lead from a lead-bearing ore concentrate. The lead-bearing ore concentrate is leached with a solution of cupric chloride in order to precipitate lead as lead chloride, produce elemental sulfur and substantially leave the balance of the ore concentrate sulfides in unreacted form. The residue of the cupric chloride leach is leached with a brine solution in order to solubilize the lead chloride to the exclusion of the balance of the residue. Thereafter, the lead chloride is crystallized from the brine solution. Elemental lead may be obtained by the reduction of the lead chloride crystals.The present process avoids air pollution problems inherent to smelting processes, allows for a high recovery of lead of 97% or greater and allows for the direct production of a high purity lead.

Abstract: A process for treating sulfide ores to reduce the sulfur content or recover the metal content therefrom comprises the use of enzymatic action to solubilize the sulfur and metal content.A nutrient, such as a saccharide, is used along with yeast spores which feed on the sugar and produce enzymes which act on sulfur in the sulfide ore to cause the sulfur to go into solution and to dissolve those metals which are soluble in strongly acidic solution. Sulfuric acid can be formed from the sulfide ores or from free sulfur by reaction with water, with evolution of hydrogen sulfide gas. Oxidation of at least a portion of the hydrogen sulfide can be achieved to regenerate sulfuric acid.

Abstract: The present invention relates to a process for treating residues from a primary leaching of ferriferous zinc ores by sulphuric acid, with a view to recover a leadbearing by-product, such process comprising a secondary leaching of said residues, by sulphuric acid, within several countercurrent stages, at a temperature comprised between 85.degree. and 100.degree. C., the solid residues of the successive stages being circulated from the first to the last stage, the residue of this last stage being the said lead bearing by-product, whereas the various solutions separated from the second to the last stage are each recycled within the leaching operation of the respectively foregoing stage, and the dual zinc and iron sulphates solution, as separated from the first stage, being the principal product of the treatment.

Abstract: Solid carbonaceous fossil fuels such as coal, lignite and peat are treated with an aqueous medium containing a novel catalyst to remove undesirable constituents and produce valuable products. The catalyst is prepared by steps including admixing a water soluble alkali metal silicate with an aqueous medium containing carefully controlled amounts of dissolved water soluble substances which are sources of calcium ion and magnesium ion, reacting the same to produce an aqueous colloidal suspension of the reaction product, admixing a micelle-forming surfactant with the aqueous medium, and agitating the aqueous medium containing the colloidal particles and surfactant to form catalyst-containing micelles. In one variant, particles of a fossil fuel containing metal values are treated with an aqueous medium in the presence of the catalyst, and thereafter the treated particles are separated from the aqueous medium and extracted with an aqueous leach solution in which the metal values are soluble.

Abstract: A multi-step process for recovering metal values from lead smelter matte. The matte is mixed with sulfuric acid and manganese oxide and leaching is effected at atmospheric pressure to form an aqueous solution including dissolved metal sulfates and a residue containing sulfur and lead sulfate. The sulfur is removable by conventional means and the lead sulfate may be returned to the smelter. The pH of the aqueous sulfate solution is adjusted to 3.5 to 4.5 to precipitate ferric iron and arsenic and pH is readjusted to about 3.0 to redissolve coprecipitated copper. After separation from the precipitate, the aqueous solution is mixed with a sulfiding agent, such as sodium sulfide at a pH of not more than 3 to selectively precipitate copper sulfide. After separating the copper sulfide, the aqueous solution is mixed with further sulfiding agent at a pH of 3 to 4.5 to form a cobalt-nickel sulfide precipitate in which the weight ratio of copper-nickel to sulfur is 1.8.

Abstract: Process and apparatus for the electrowinning of metals from sulphide ores wherein a sulphide ore is initially leached in a water soluble sulphide solution, alkali is then added, and the resulting solution is electrolyzed so as to deposit metal at the cathode and obtain water soluble sulphide as a by-product. The process is particularly suitable for obtaining antimony from stibnite.

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 method of detoxifying organotin-containing paint residues that are sandblasted from the bottom of a ship's hull comprising cleaving the tincarbon bond by application of an oxidizing agent, preferably nitric acid.

Abstract: A flotation process for concentrating tungsten or tin ores is achieved by grinding the ores with a grinding medium other than steel, first conditioning a deslimed sulfide free pulp with an acid, further treating the pulp with an emulsified collector and recovering the tungsten or tin in the float. The flotation concentrate can be further enriched by leaching with an inorganic acid.

Abstract: The process of the invention is for the separate recovery of elemental sulfur and residual sulfides and metal salt solution from reaction slurries obtained from leaching of metal sulfides in ores and concentrates.

Abstract: A process for separating lead and zinc from oxidized ore is disclosed. The process is directed to the ammoniacal leaching of the ore in the presence of the anions of polycarboxylic acids, particularly sodium tartrate, and the subsequent selective extraction by means of complex-producing solvents.

Abstract: This invention provides a process for treating a nickel matte to recover essentially pure nickel comprising: treating an aqueous mixture of the matte with chlorine to produce a solid residue and an aqueous lixiviating solution having a pH value which is substantially nil or positive; treating the lixiviating solution to produce a solution containing primarily nickel chloride; and electrolyzing the solution to recover pure nickel at the cathode.

Abstract: A method for the dissolution of non-ferrous metals contained in oxygenated compounds in which the oxygenated compounds are subjected to the action of a ferrous chloride solution and a gas containing oxygen is mixed with the solution.

Abstract: Lead values may be recovered from lead bearing sources such as lead sulfide in improved purity. The improved purity is obtained by subjecting soluble lead halides formed by the halogenation of lead sulfide and brine leaching the chlorinated product prior to treatment with a reducing agent followed by filtration and further treatment with an oxidizing agent whereby impurities as represented by other metal values are removed.

Abstract: A hydrometallurgical process for recycling the paste and electrolyte of junk lead-acid batteries begins by separating the paste and electrolyte from the junk batteries. The paste and electrolyte are then reacted to increase the lead sulfate content of the paste and reduce the acid content of the electrolyte. Excess liquid is then removed from the mixture of paste and electrolyte, after which the paste is mixed with an aqueous ammoniacal ammonium sulfate solution to dissolve a substantial portion of the lead sulfate from the paste. The remaining solid materials are then separated from the resulting pregnant lead solution, after which lead carbonate is precipitated from the pregnant lead solution by the addition of ammonium carbonate, ammonium bicarbonate or carbon dioxide.

Abstract: A process for extracting non-ferrous metal values from an oxide ore. The process comprises leaching the ore with a solution containing at least one alkali metal chloride or alkaline earth chloride salt in the presence of an oxygen-containing gas at a temperature and pressure sufficient to solubilize the non-ferrous metal values into the solution of the metal chloride salt.

Abstract: An improvement in the method for recovering marketable values of solder, lead, and a zinc chloride-ammonium chloride solution from solder skimmings which comprises grinding the skimmings, water leaching the skimmings to dissolve the zinc chloride and ammonium chloride, screening the leach residue to recover solder from the leach slurry, separating the ammonium and zinc chloride solutions from the lead chloride in the leach slurry, and contacting the lead chloride with an alkaline flux, a reductant, and an oxygen-containing gas under heat to recover lead from the lead chloride.

Abstract: The invention provides a process for recovering germanium as germanium oxide from a germaniferous metallic zinc which involves distilling the germaniferous metallic zinc under non-oxidizing conditions, recovering the distillation residue which contains the germanium, leaching the recovered distillation residue with chlorine water to convert the germanium into germanium tetrachloride, hydrolyzing the germanium tetrachloride into germanium oxide, and recovering the germanium oxide. Optionally, the germanium oxide may be reduced to metallic germanium, if desired.

Abstract: Copper, iron, and lead impurities are removed from molybdenum flotation concentrates by mixing the feed concentrates with a nonvolatile chloride salt, heating the mixture to a temperature of from about 200.degree. to 350.degree. C for a time sufficient to activate the lead impurities in the concentrates so that they can be leached therefrom during the subsequent leach step, and leaching copper, iron, and lead impurities from the heat-treated concentrates with a mildly oxidizing leach solution containing chloride ions and having a pH of no more than 4. Preferably, the mixing of the chloride salt and the feed concentrates is achieved by thoroughly mixing an aqueous solution of the salt with the feed concentrates.

Abstract: A process for the treatment of complex lead sulfide-containing concentrates additionally containing at least one metal of the group consisting of iron, copper, zinc, silver, arsenic, antimony, bismuth and gold which comprises the steps of selectively leaching a concentrate with iron-containing lixiviant for converting lead sulfide in said concentrate to lead chloride and forming a leach residue and a leach solution, subjecting said lead chloride in the leach residue to a two-stage, countercurrent, hot brine leach to dissolve the lead chloride in a brine-leach solution, subjecting the brine leach solution to crystallization by evaporative cooling for the separate recovery of crystallized lead chloride, residual brine and crystallization condensate, and returning said residual brine to said brine leach, subjecting crystallized lead chloride in admixture with sodium chloride to electrolysis in a fused bath for production of lead and evolution of chlorine, absorbing chlorine in a first portion of said leach solut

Abstract: A process for the re-utilization of the sulphate residues from the electrolytic treatment of zinc.The residues are digested hot with concentrated HCl in the presence of CaCl.sub.2. PbCl.sub.2 crystallizes on cooling. FeCl.sub.3 is extracted with TBP circulating in the direction of a series of columns and FeCl.sub.3 is extracted in a first column, washed in a second column and re-extracted a third column. The solution which issues is treated with NH.sub.3, resulting in precipitation of the majority of the hydroxides of the metals contained therein, which are subsequently separated, while Ag, Zn and Cu are complexed. Ag is precipitated with (NH.sub.4).sub.2 S.NH.sub.3 is recovered by means of lime. CaCl.sub.2 is re-cycled to the start of the process and Cu and Zn are leached together with the mineral.Application of the process to the recovery of the metals contained in the residues from the digestion of blends.

Abstract: This invention relates to a process for hydrometallurgical treatment of concentrates of sulphides of copper, nickel, cobalt, lead and iron and copper-containing mattes. A first embodiment of the process includes subjecting a finely ground slurry of a sulphide concentrate to an oxidation leach at elevated temperature and pressure in the presence of an oxygen-bearing gas to preferentially leach cobalt and nickel and to convert galena to lead sulphate. The reaction mixture is heated to a further elevated temperature, in the absence of oxygen, to convert a portion of chalcopyrite to insoluble simple copper sulphides and ferrous sulphate solution and to decompose complex insoluble ferric compounds. The resulting mixture is subjected to differential flotation whereby a lead concentrate and a copper concentrate are obtained.

Abstract: An improvement in conventional processes for recovering metal values from sulfide ores containing lead, zinc and silver sulfides in which process the metal sulfides are converted to chlorides by chlorination followed by solubilization of the chlorides with a sodium chloride leach and subsequent recovery of the metals from their chlorides in accordance with a conventional flow sheet including crystallization, cementation, precipitation, fused salt electrolysis, etc., with chlorine being recovered for reuse by electrolysis of the sodium chloride leach solution substantially depleted of lead, silver and zinc, the improvement being a pollution-free process which comprises:1. recycling the sodium chloride solution depleted of a major percentage of lead and silver to the sodium chloride or brine leaching step; and2.

Abstract: This invention relates to refining platinum group metal concentrate and the separation therefrom of silver and the majority of base metals which are present in them. In more detail, the process comprises the steps of:A. contacting a solid particulate mixture of base, silver and precious metal components, any of which may be in metallic or in chemically combined form, with substantially anhydrous sulphuric acid at a temperature which is sufficiently high for most of the base metal and silver components to form water soluble sulphates andB. separating the said water soluble sulphates from the solid precious metal-containing components by contacting the product from step (a) with a dilute aqueous solution or water and dissolving therein the said water soluble sulphates formed in step (a).