Abstract: Heavy Metals contained in industrial waste streams are removed therefrom by flocculation using a source of ferric ions and an alkaline material at a basic pH. Both the flocculated heavy metals and the coagulant chemicals are recovered by acidifying the floc to a pH of between 3.2 and 3.7. This liberates the heavy metals back into solution but does not destroy the floc particles. After separation and removal of the concentrated heavy metal solution, the floc is further acidified to completely dissolve it. This dissolved ferric ion containing solution may then be reused to treat succeeding portions of heavy metal containing waste streams. The concentrated heavy metals solution may also be recycled or the metals contained therein recovered for reuse or disposed of in an acceptable manner.

Abstract: A process for the recovery of silver values from silver-containing material which also contains iron and arsenic includes leaching the material under oxidizing conditions at elevated temperature and pressure in aqueous nitric acid solution to dissolve a substantial amount of silver together with substantial amounts of arsenic, iron and other metals if present. The resultant leach solution is separated from undissolved leach residue and treated with a solution containing chloride ions to selectively precipitate substantially all dissolved silver as silver chloride without significant co-precipitation of other dissolved metals. The silver chloride precipitate is then separated from the remaining solution.

Abstract: Process of carrying out oxidation-reduction reactions such as oxidation of hydrogen sulfide to sulfur, in which a polyvalent metal chelate with a certain class of polycarboxylic acid is employed, the metal being reduced from a higher valence state to a lower valence state during reduction and back to the higher valence state by oxidation. The class of polycarboxylic acids are those which have a substituent which enhances acidity yet is stable toward oxidation.

Abstract: A process for treating an aqueous acidic solution containing a large amount of ferric ion and other metal ions such as a hydrochloric acid solution of manganese nodules, which includes contacting the aqueous solution with an organic extractant to selectively extract the ferric ion therefrom. The extractant is comprised of a dialkylphosphoric acid having 6-12 carbon atoms and a hydrocarbon solvent such as kerosene. The aqueous phase obtained after the extraction is then added with a pH-controlling agent to increase the pH thereof to a value so that unextracted ferric ion remaining therein may precipitate as ferric hydroxide while the other metal ions may be prevented from precipitating. Solid-liquid separation of the resulting mixture gives a solution having a ferric ion concentration of about 0.1 g/l or less. The pH-controlling agent is preferably an industrial waste containing a metal oxide or hydroxide such as a sludge from plating industries.

Abstract: Precipitation-free recovery of catalyst metal content of residue from manufacture of benzene carboxylic acid by oxidation with source of molecular oxygen of liquid methyl-substituted benzene in presence of cobalt, manganese, cerium, and mixtures of two or more thereof followed by removal of benzene carboxylic acid and, if used, reaction solvent. Such precipitation-free method comprises extracting such residue with water, contacting the resulting extract solution or suspension of insolubles in extract solution with one side of a cation permeable fluoropolymer membrane and contacting the opposite side of the membrane with a hydrohalidic acid.

Abstract: Precipitation-free recovery of catalyst metal content of residue from manufacture of trimellitic acid by oxidation with source of molecular oxygen of liquid pseudocumene in presence of cobalt and manganese, cobalt, manganese and cerium, followed by removal of trimellitic acid or its anhydride and, if used, reaction solvent and then separating manganese from the recovered metals. The foregoing is accomplished by extraction of such residue with water, contacting the resulting aqueous extract solution or suspension of insolubles in the aqueous solution with one side of a cation permeable fluoropolymer membrane whose other side is in contact with a hydrohalidic acid to permit metal ions to pass through the membrane, removing the hydrohalidic solution of the catalyst metals, and then after a pH adjustment adding metallic manganese to precipitate cobalt as metal.

Abstract: Recovery of cobalt and manganese metal oxidation catalysts from residue of trimellitic acid manufacture and separation of recovered cobalt from recovered manganese can be accomplished by a novel method involving dissolving the residue in water, displacing dissolved cobalt as cobalt metal by manganese metal added to the solution whose pH has been adjusted to pH of 6 and then using magnetic means for separating metallic cobalt from the cobalt-free solution.

Abstract: Cobalt and manganese are recovered from incineration ash obtained by combustion of residue from the manufacture of trimellitic acid and its recovery as 4-carboxyphthalic anhydride and then the recovered cobalt is separated from the recovered manganese by magnetic separation. The foregoing is accomplished by extraction of the ash with an aqueous solution of hydrogen bromide or chloride, recovery of the extract solution, and the upward adjustment of its pH while adding powdered manganese to precipitate metallic cobalt for its separation by magnetic means.

Abstract: A process for precipitating iron as a jarosite from a sulphate solution containing ferric iron, free acid and valuable non-ferrous metals, characterized by cooling the solution; partially neutralizing the free acidity, and then clarifying the solution; heating the clarified solution to a temperature not exceeding the boiling point at atmospheric pressure, in the presence of at least one ion selected from the group consisting of sodium, potassium and ammonium ions, and in the presence of recycled jarosite, and without the addition of any further neutralizing agent, so that substantially all of the ferric iron is precipitated as a jarosite; and separating precipitated jarosite from the solution; thereby producing a jarosite contaminated with only minor amounts of non-ferrous metals, and a solution which may be further processed by established procedures for the recovery of dissolved valuable non-ferrous metals therefrom. The invention also contemplates a dilution step, and recycle of jarosite.

Abstract: In a process according to the present invention pre-reduced lateritic ores containing iron and nickel are leached with an aqueous sulphuric acid leach liquor containing or into which is introduced in the presence of the ore a peroxidant selected from hydrogen peroxide and peroxymonosulphuric acid. By so doing, the liquor is obtained with a lower concentration of iron than if the peroxidant had not been employed.In preferred embodiments the leaching is carried out at from 40.degree. to 70.degree. C. for a period of 1 to 5 hours; when hydrogen peroxide is used, it is preferably introduced continuously or progressively throughout the reaction period and when peroxymonosulphuric acid is used it is preferably introduced initially. The acidity of the liquor can be reduced at the end of the reaction to pH3 to 4 to further lower the content of iron in solution.

Abstract: A unique method of separating cobalt and manganese from residue obtained from the manufacture of trimellitic acid by the oxidation of pseudocumene in the presence of cobalt and manganese as metal oxidation catalysts and from each other without contributing to the problem of solids disposal. Said unique method comprises extracting the residues with water, removing cobalt and mangangese from the extract solution with a cation exchanger thereby producing a metal-free solution of trimellitic acid, regenerating the cation exchanger with a strong inorganic acid, adjusting the pH of the spent regenerating acid to pH of 3 to 4 if iron is present to precipitate it as its hydroxide but at least to pH of 6 while also adding powdered manganese to precipitate metallic cobalt.

Abstract: Recovery of cobalt and manganese from residue of trimellitic acid manufacture and recovery as 4-carboxy-phthalic anhydride by extracting the residue with an aqueous alkaline solution containing carbonate ions which leaves a precipitate of metal carbonates, dissolving said precipitate as the metal chlorides, and at an upwardly adjusted pH adding powdered manganese to precipitate metallic cobalt and separating it by magnetic means.

Abstract: A method of recovering metallic tellurium from a residue dust containing a major amount of lead oxide, a minor amount of tellurium oxide, and a minor amount of iron oxide which comprises the steps of introducing the residue into a leach tank containing water, sulphuric acid and ferric sulphate, the sulphuric acid being present in the leach tank in an amount equal to about 5% to 10% by weight in excess of that stoichiometrically required to react with the lead and tellurium, the ferric sulphate being added as an oxidizing agent, reacting the residue with the sulphuric acid and ferric sulphate to produce lead sulphate and a tellurium solution, removing the lead sulphate and tellurium solution from the leach tank and separating the lead sulphate from the tellurium solution, adding the separated tellurium solution to a tumbler containing particles of metallic iron, agitating the tumbler so that the tellurium solution reacts with the iron to produce ferrous sulphate and metallic tellurium, withdrawing the mixture

Abstract: This invention relates to the reclamation of metal oxidation catalysts by water extraction of a high boiling residual mixture remaining after separation of a benzene di- and/or tricarboxylic acid; e.g., the phthalic acids, trimesic acid or trimellitic acid and reaction solvent, if one is used, from the fluid oxidation effluents produced by the catalytic liquid phase oxidation of a xylene, mesitylene, psendocumene or o-xylene and psendocumene with a source of molecular oxygen in the presence or in the absence of a reaction solvent.

Abstract: A slurry, such as might be obtained from acid leaching nickeliferous ores having a high iron content, is treated to separate dissolved nickel or cobalt from iron oxide solids. The treatment involves a controlled precipitation of the non-ferrous metal with the aid of calcium sulfide or barium sulfide followed by flotation to recover a high grade concentrate of the non-ferrous metal.

Abstract: Cobalt is recovered from byproduct streams from a basic process by contacting the byproduct streams with aluminum metal for a sufficient period of time to produce cobalt metal as a precipitate. The basic process is the type wherein cobalt ions in solution are complexed with ammonia in the presence of halide ions to form an ammine halide solution from which a cobalt containing precipitate is separated. The precipitate is subsequently reduced to form a cobalt metal powder.

Abstract: In a hydrometallurgical treatment for eliminating one or more metal impurities from a solution containing a metal to be extracted and said metal impurities, a silicate is added to the solution forming in situ dissolved silicic acid and precipitating the metal impurities at a pH of between 1.5 and 4.5 to form a solid silicate residue.

Abstract: A process for beneficiating ilmenite ore using electrolytic reduction. The ilmenite ore is admixed with an acidic solution to form a mixture. The mixture is electrolytically reduced to convert at least a portion of any ferric iron that is present to ferrous iron. The acidic solution dissolves the ferrous iron in the ilmenite ore and yields beneficiated ilmenite having a relatively high titanium dioxide content.

Abstract: A method of producing magnesium sulphate comprises the steps of interacting ferrous sulphate with compounds including magnesium carbonates, oxides and hydroxides, with magnesium sulphate being produced. The step of interacting the starting reagents is conducted in water medium in the presence of carbon dioxide and is effected in the range of temperatures of 80.degree. to 100.degree. C.

Abstract: A method for thermally decomposing manganese nitrate in an aqueous solution containing alkali and/or alkaline earth nitrates including splashing said aqueous solution containing manganese nitrate to form droplets or sheets of solution, heating said droplets or sheets of solution to partially decompose each droplet or sheet of solution to form manganese dioxide and nitrogen dioxide, and reuniting said droplets or sheets of solution containing manganese dioxide with said aqueous solution containing manganese nitrate; and/or spraying said aqueous solution containing manganese nitrate to form droplets of solution, heating said droplets of solution to fully decompose each droplet to form nonstoichiometric manganese dioxide, and nitrogen dioxide, and recovering said nonstoichiometric manganese dioxide.

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 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: The invention relates to a method of controlling acid soluble iron while obtaining solutions of copper (I) salts in water containing an organo nitrile (selected from the group consisting of acetonitrile, 2-hydroxycyanoethane, acrylonitrile and propionitrile) from materials containing copper and iron compounds, said solutions having a low iron content, which method comprises leaching the material with a solution of copper (II) salt in water containing the selected organo nitrile, the amount of nitrile present being sufficient to stabilize the resulting copper (I) solution and the pH of the mixed solution being controlled in relation to the relative concentrations of the copper (II) salt, copper (I) salt and nitrile to ensure that the iron compounds are not significantly soluble therein, and then separating the copper (I) solution from the insoluble materials.

Abstract: This invention relates to the removal of nickel, iron and copper co-dissolved with cobalt or manganese, or cobalt and manganese in water so that cobalt, manganese, or cobalt and manganese can be precipitated as carbonates and then converted to their acetates sufficiently low in nickel, iron and copper so that said acetates can be recycled to the liquid phase air oxidation of a di- or trimethyl benzene to its corresponding di- or tricarboxylic acid without material inhibition of such oxidation.

Abstract: This process reduces the soluble iron found in the final effluent of a plant making iron oxide by the Penniman-Zoph scrap process. The finished oxide product slurry is separated from the scrap iron, and the slurry is aerated while the pH is maintained between about 3.0 and 5.0. As the soluble iron is converted to product oxide, the pH of the system rises toward the higher value.

Abstract: Clusters or galaxies of noble metal silver-precipitating nuclei for use in silver diffusion transfer processes are formed by reducing a noble metal salt or complex to form a colloid of noble metal nuclei and inducing instability to said colloid, whereby said galaxies are formed.

Abstract: Silver-precipitating nuclei are prepared by partially oxidizing a stannous salt reducing agent and then reducing a noble metal salt or complex with said reducing agent.

Abstract: Process for extraction and separation of metals utilizing the advantages of liquid-liquid extraction with cation exchangers without requiring the equivalent addition of alkali. The process is based on a combination of leaching the metal-containing raw materials with an organic acid (cation exchanger) and a subsequent use of the formed metal cationic complex in a liquid-liquid extraction process. In the said extraction process, the organic solution of metal complexes is used to recover and separate metal ions from an aqueous solution of metal salts.

Abstract: The present invention relates to a process for the recovery of manganese from aqueous acidic solution.The process comprises the steps of, (a) introducing into the solution peroxymonosulphuric acid (PMS) in a plurality of stages, normally from 2 to 6, often in the range of from 110 to 160% of the amount theoretically needed to oxidise the manganese to the Mn (IV) oxidation state, (b) introducing from 100 to 133% of the theoretical amount of neutralising agent to neutralise the PMS introduced in step (a), preferably in a single addition and prior to the introduction of the second stages of PMS and, (c) separating precipitated manganese salt from solution. The demanganisation reaction is preferably carried out at a temperature of above 60.degree. C. usually in the range of 70.degree. to 90.degree. C.An aqueous acidic manganese-containing solution can be obtained by leaching ores or scrap metal with strong mineral acids.

Abstract: A process for precipitating iron as a jarosite from a sulphate solution containing ferric iron, free acid and valuable non-ferrous metals, characterized by cooling the solution; partially neutralizing the free acidity, and then clarifying the solution; heating the clarified solution to a temperature not exceeding the boiling point at atmospheric pressure, in the presence of at least one ion selected from the group consisting of sodium, potassium and ammonium ions, and in the presence of recycled jarosite, and without the addition of any further neutralizing agent, so that substantially all of the ferric iron is precipitated as a jarosite; and separating precipitated jarosite from the solution; thereby producing a jarosite contaminated with only minor amounts of non-ferrous metals, and a solution which may be further processed by established procedures for the recovery of dissolved valuable non-ferrous metals therefrom. The invention also contemplates a dilution step, and recycle of jarosite.

Abstract: Iron metal values and titanium metal values may be recovered from iron and titanium bearing sources such as ilmenite by subjecting the source to a reductive roast followed by leaching of the reduced source with a halogen-containing compound. Thereafter, the iron halide is crystallized and separated from the soluble titanium halides. One portion of the iron halides is subjected to a reducing step to form metallic iron while a second portion is oxidized, the iron oxides being used to precipitate the titanium as titanium dioxide. The titanium dioxide may then be separated and recovered while the liquid portion is recycled to the leaching zone.

Abstract: Iron metal values and titanium metal values may be recovered from iron and titanium bearing sources such as an ilmenite ore by subjecting the source to a reductive roast after crushing the source to a desired particle size. The reduced source is then leached by treatment with a halogen-containing compound to form soluble titanium halides and iron halides. Thereafter the soluble titanium halide is precipitated by treatment with iron oxides such as ferric oxide and after separation from the soluble iron halides is recovered as titanium dioxide. The soluble iron halides are then crystallized by reducing the temperature of the solution and one portion of the crystals are subjected to a reduction step to form metallic iron. The other portion of the iron halide crystals is oxidized to form ferric oxide which is used to precipitate the titanium compound.

Abstract: Titanium metal values may be recovered from titanium and iron bearing sources such as an ilmenite ore by subjecting the source to an oxidation treatment and a reductive roast after having crushed the source to a desired particle size. The reduced source is then leached by treatment with a halogen-containing compound to form soluble titanium halides and iron halides. Thereafter the soluble titanium halide is precipitated as titanium dioxide by treatment with an iron oxide such as ferric oxide and recovered. The amount of titanium dioxide which is recovered is determined by the amount of reductant utilized in the reductive roast.

Abstract: Titanium metal values are recovered from a titanium bearing source such as an ilmenite ore by subjecting the source to a reductive roast and leaching the reduced source with a halogen-containing compound. Following this the soluble metal halides are separated from gangue and the pregnant leach liquor if treated with an iron oxide such as ferric oxide to precipitate titanium dioxide. The nucleation of the titanium dioxide may be improved by using a large excess of ferric oxide in the precipitation step. The improvement will thus result in an increased yield of the desired titanium dioxide.

Abstract: Titanium metal values may be recovered from a titanium bearing source such as an ilmenite ore by subjecting the source to a reductive roast, leaching the reduced source with a halogen-containing compound followed by crystallization of the iron halide impurity which is separated from the soluble titanium halide. The soluble titanium halide is then treated with an iron oxide to form titanium dioxide. The yield of titanium dioxide may be greatly improved by effecting the nucleation of the titanium in a manner which comprises adding the iron oxide to the solution without agitation. Upon completion of the nucleation reaction, the solids are then thoroughly dispersed before removing the solid titanium dioxide.

Abstract: An aqueous sodium chloride solution for use in production of caustic soda in an electrolytic cell having a cation exchange membrane is purified by adding to said solution a chemical reagent for precipitation separation of impurities remove silica through co-precipitation with a slurry of the precipitates of impurities which are circulated through said solution.

Abstract: Gypsum and magnetite which are both coarse and of good quality can simultaneously be produced by introducing calcium carbonate into an aqueous solution containing ferrous sulfate while an oxidizing gas is blown, and then carrying out a neutralizing and oxidizing operation at a pH of 5-6 and a temperature of 60-80.degree. C, and can be separately recovered by magnetic separation.

Abstract: Aqueous lead solutions obtained by hot chloride leaching of residues containing lead and silver ore are subjected to selective precipitation of the silver as silver sulphide, with e.g. hydrogen sulphide. The silver can then be recovered in a known manner. Lead can be precipitated from the remaining solution as a basic salt also in a known manner. If the initial residue contains copper, it is also precipitated as sulphide. The copper sulphide can be separated from the precipitate by selectively dissolving the copper with sulphuric acid under an elevated oxygen pressure. Elemental sulphur is formed and the silver sulphide can be separated from the elemental sulphur in a known manner.

Abstract: A process for removing zinc from an aqueous solution of a nickel salt by liquid-liquid extraction using as the extraction agent an organic phosphoric acid dissolved in an organic solvent, adding a strongly oxidizing substance at an elevated temperature to the aqueous phase emerging from the extraction to precipitate the cobalt as a hydroxide and decompose the organic phase left in the aqueous phase and to adsorb it into the cobalt hydroxide precipitate, and finally separating it from the pure aqueous nickel salt solution.

Abstract: A method for selectively extracting metal values from manganese bearing ores such as marine nodules. The ore is initially leached to solubilize manganese and other desirable metals as nitrates. The resulting solution is then treated with manganous hydroxide to selectively precipitate metals such as copper, nickel and cobalt. The enriched mixture of metal hydroxides is separated from the manganese nitrate solution, which is decomposed to recover high purity MnO.sub.2.

Abstract: A process is described for the separation of platinum group metals (PGM) from ores also containing iron, nickel and copper as sulfides. The minerals in the ore are first concentrated by flotation and the ore concentrate is melted in an electric furnace to form a matte containing at least 95% of the precious metals. The matte is granulated while molten to granules of a mean size not greater than about 210 micrometers (.mu.m) and then pressure leached with sulfuric acid and oxygen to separate the nickel, iron and copper as their respective sulfates, while recovering the PGM as a residue. Concentration of the leach residue by roasting and subsequent acid leaching yields a final PGM product containing the major portion of the precious metals in the ore and substantially all (i.e., at least about 95%) of the precious metals in the ore concentrate and which contains less than 1% total nickel, iron and copper.

Abstract: A process for extracting copper from a copper bearing ore or concentrate which comprises immersing the ore or concentrate in an electrolyte, intimately mixing with the slurry so formed finely dispersed air or other oxygen-containing gas and maintaining the pH of the mixture at above 1.5 and below 7.0 throughout the process. Iron is solubilized in the process and precipitated as ferric oxide and the copper is taken into solution in which copper is primarily present as cuprous ions. The process is conducted at substantially atmospheric pressure and at temperatures of from 50.degree. C to the boiling point of the electrolyte. The electrolyte is acidic and contains chloride ions in a concentration between that sufficient to maintain in solution cuprous ions present and saturation.

Abstract: A process is disclosed for preparing .alpha.-Fe.sub.2 O.sub.3 in the form of acicular particles substantially free from occluded boils or cavities, and containing from 0.2 to 2% by weight of SiO.sub.2, and having a mean axial ratio between 6 and 8, and an intrinsic coercive force of 320 - 370 Oe. An aqueous solution of FeSO.sub.4. 7H.sub.2 O is treated with alkali, in the presence of air, thus forming acicular .alpha.-FeOOH, which is then dehydrated, reduced at Fe.sub.3 O.sub.4 under fluidizing conditions, and oxidized to .gamma.-Fe.sub.2 O.sub.3 at 200.degree.-350.degree. C under fluidizing conditions. The formation of the acicular .alpha.-FeOOH is carried out at a yield of 0.5-2.5 kg of ferric Fe per hour per m.sup.3 of reactor; the reaction product is filtered and washed and the .alpha.-FeOOH particles are coated with 0.2-2% by weight of SiO.sub.2, from an aqueous suspension of .alpha.-FeOOH brought to a temperature ranging from 50.degree. to 90.degree. C, adding Na.sub.2 SiO.sub.

Abstract: Process for removing impurities selected from the group consisting of manese, cobalt, nickel and thallium from an acidic zinc or cadmium solution comprising adding thereto acid of Caro or an ammonium or alkali metal salt thereof.

Abstract: Sufficient anionic polyacrylamide having molecular weight of at least 2,800,000 is contacted with alkali metal aluminate liquor containing ferrous iron until a substantial proportion of the ferrous iron is precipitated, and said precipitate and liquor are separated. The process is particularly useful as an improvement in the Bayer process for preparing alumina from bauxite.

Abstract: An improved method for producing iron hydrosulfite liquor by reduction of sulfur dioxide with metallic iron is disclosed. Also disclosed are improvements in the conversion of the iron hydrosulfite liquor to produce sodium hydrosulfite bleach liquors.

Abstract: A process for the precipitation of metallic sulfides, e.g., nickel, cobalt or zinc sulfides, from aqueous metal-ion-containing solution comprising passing hydrogen sulfide through the metal-containing solution while the solution is at a temperature of about 75.degree. C. and at a pH of about 2 to about 3 and maintaining said pH during the time of hydrogen sulfide addition by continuous addition of alkali to the solution. The precipitated metal sulfide is characterized by a relatively large particle size by a high settling rate and by ease of filterability.

Abstract: A process for the treatment of nickel-copper concentrates comprises the steps of leaching nickel selectively with a dilute hydrochloric acid solution, separating the leach solution from the residue, roasting the residue at a temperature sufficient to form at least about the stoichiometric quantity of sulphate to convert all the nickel present in the residue to nickel sulphate, leaching the roasted residue with water and precipitating any dissolved copper from the aqueous leach solution thus obtained.

Abstract: A process which enables cumulative recovery of nonferrous metal values from manganiferous sea nodules and a limonitic ore comprises treating the limonitic ore in an aqueous acidic medium under reducing conditions to extract nonferrous metals and iron from the ore and form a solution containing ferrous iron and then leaching the sea nodules with such solution to extract nonferrous metals from the sea nodules and precipitate a predominant amount of the iron as hydrated ferric oxide.

Abstract: A process is provided for extracting iron values as soluble ferrous salts from a limonitic ore which comprises leaching the ore in an acidic medium in the presence of a reducing agent, the reducing agent being a sulfide. Non-ferrous metal values are also extracted from the ore and they may be selectively separated from the solubilized iron salts.