Abstract: This invention relates to a hydrometallurgical process for extracting platinum group metals (PGMs), gold, silver and base metals from a flotation concentrate (10) containing sulphide minerals such as pentlandite and chalcopyrite, along with pyrite and pyrrohotite. The process includes a modified pressure oxidation step (12) to selectively separate base metals into sulphate medium (14), from the PGMs. The modified pressure oxidation step (12) partially or completely oxidizes sulphide minerals to produce a product slurry (14) containing base metal sulphates in solution and a solid residue containing PGMs along with sulphate and elemental sulphur. The solid residue is subjected to a thermal treatment (18) to remove sulphate and elemental sulphur from the solid residue, and to condition the PGMs to be soluble in chloride medium. The treated solid residue is the subjected to PGM recovery by leaching in chloride leaching medium (20) to recover the PGMs.

Abstract: Process for preparing an aqueous cobalt sulfate solution having a pH of at least 4, wherein (a) metallic cobalt is dissolved in aqueous sulfuric acid in an atmosphere of low-oxygen air, of hydrogen or of inert gas and (b) the resulting acidic cobalt sulfate solution is treated with oxygen, oxygen-comprising gas or with a substance which can release oxygen in an aqueous medium.

Abstract: Process for preparing an aqueous cobalt sulfate solution having a pH in the range from 5 to 8, wherein (a) metallic cobalt is dissolved in aqueous sulfuric acid in an atmosphere of low-oxygen air, of hydrogen or of inert gas and (b) the resulting acidic cobalt sulfate solution is purified in an ion exchanger.

Abstract: Provided is a method of producing high-purity nickel sulfate by an impurity-element removal method for selectively removing Mg from a Ni-containing solution.

Abstract: It is an object to provide a method for producing magnesium oxide by which magnesium oxide being high in purity and low in impurity content can be produced simply and efficiently from a sulfuric acid solution containing magnesium and calcium such as waste water. In the present invention, calcium is precipitated as calcium sulfate and separated by concentrating a sulfuric acid solution containing magnesium and calcium, and magnesium is precipitated as magnesium sulfate and separated by further concentrating the solution resulting from the separation of calcium. The separated magnesium sulfate is roasted together with a reductant, so that magnesium oxide and sulfur dioxide are obtained. The resulting magnesium oxide is washed to produce magnesium oxide with high purity.

Abstract: A process for treating spent pickle liquor has the steps of mixing the spent pickle liquor with sulfuric acid, introducing oxygen into the mixture of spent pickle liquor and the sulfuric acid for a period of time, and producing diiron(II) tetrachlorosulfate from the oxygen-introduced mixture of sulfuric acid and spent pickle liquor. The spent pickle liquor and the sulfuric acid are introduced into a column. The oxygen is passed under pressure into the column. The intimate mixture of spent pickle liquor, sulfuric acid and oxygen are maintained under pressure for a period of time.

Abstract: A process for treating spect pickle liquor has the steps of mixing the spent pickle liquor with sulfuric acid, introducing oxygen into the mixture of spent pickle liquor and the sulfuric acid for a period of time, and producing diiron(II) tetrachlorosulfate from the oxygen-introduced mixture of sulfuric acid and spent pickle liquor. The spent pickle liquor and the sulfuric acid are introduced into a column. The oxygen is passed under pressure into the column. The intimate mixture of spent pickle liquor, sulfuric acid and oxygen are maintained under pressure for a period of time.

Abstract: The invention relates to a method for separating nickel and other valuable metalsparticularly from material having low nickel content, which contains iron and magnesium in addition to nickel and other valuable metals. The material havinglow nickel content is subjected to pulpingand atmospheric leaching in acidic and oxidising conditions, in which the majority of the metals in themate-rialdissolve and the iron is partially precipitated. The precipitated iron is sepa-rated from the solution, after which nickel and the other dissolved valuable metalsare precipitated as sulphides.

Abstract: The invention provides a process for the production of ferrous sulphate monohydrate which comprises: (a) reacting a source of iron with an aqueous solution of sulphuric acid in at least a first reaction vessel, to obtain a process liquor comprising ferrous sulphate and acid solution; and then (b) combining the process liquor with concentrated sulphuric acid in a mixing vessel, causing the solution to self crystallize, thus forming a slurry comprising crystalline ferrous sulfate monohydrate. The slurry can, if desired, then be converted to ferric sulphate.

Abstract: The present invention is directed to a precious metal recovery process in which basic ferric sulphates and/or jarosites are controlled by hot curing of the autoclave discharge slurry followed by decomposition of argentojarosite using strong acid consumers.

Abstract: There are provided processes for extracting aluminum ions from aluminous ores. Such processes can be used with various types of aluminous ores such as aluminous ores comprising various types of metals such as Fe, K, Mg, Na, Ca, Mn, Ba, Zn, Li, Sr, V, Ni, Cr, Pb, Cu, Co, Sb, As, B, Sn, Be, Mo, or mixtures thereof.

Abstract: A process for the recovery of nickel and cobalt from nickel and cobalt containing ores, including the steps of first leaching a laterite ore and/or a partially oxidized sulfide ore with an acid solution to produce a pregnant leach solution containing at least dissolved nickel, cobalt and ferric ions, and subsequently leaching a sulfide ore or concentrate with the pregnant leach solution to produce a product liquor. Alternatively, the laterite ore and/or partially oxidized sulfide ore can be leached in a combined leach with the sulfide ore or concentrate. The ferric ion content in the pregnant leach solution or in the combined leach is sufficient to maintain the oxidation and reduction potential in the sulfide leach high enough to assist in leaching nickel from the sulfide ore or concentrate.

Abstract: A method for recovering zinc ions by selective zinc sulfide precipitation from an aqueous solution comprising zinc ions and metal ions of a metal that precipitates as a metal sulfide at a pH lower than a pH at which zinc ions precipitate as a zinc sulfide.

Abstract: There are provided processes for extracting aluminum ions from aluminous ores. Such processes can be used with various types of aluminous ores such as aluminous ores comprising various types of metals such as Fe, K, Mg, Na, Ca, Mn, Ba, Zn, Li, Sr, V, Ni, Cr, Pb, Cu, Co, Sb, As, B, Sn, Be, Mo, or mixtures thereof.

Abstract: There is provided a method for leach extraction of copper/iron/sulphur ores and concentrates including leaching the mineral with an aqueous stream containing ferric ions and sulphuric acid in the presence of oxygen, the aqueous stream including a solution formed by reaction of basic ferric sulphate with excess suphuric acid. Integrated methods of forming and releaching basic ferric sulphate are also described.

Abstract: A method for converting nickel into a nickel salt solution. Nickel is dissolved and reacted in an oxygen-enriched acidic solution to produce a nickel salt solution as illustrated in the following chemical equation, wherein X is a conjugate base: Ni+H2X+½O2->NiX+H2O.

Abstract: The process of this invention is directed to the removal of metals from an unsupported spent catalyst. The catalyst is subjected to leaching reactions. Vanadium is removed as a precipitate, while a solution comprising molybdenum and nickel is subjected to further extraction steps for the removal of these metals. Molybdenum may alternately be removed through precipitation.

Abstract: The process of this invention is directed to the removal of metals from an unsupported spent catalyst. The catalyst is subjected to leaching reactions. Vanadium is removed as a precipitate, while a solution comprising molybdenum and nickel is subjected to further extraction steps for the removal of these metals. Molybdenum may alternately be removed through precipitation.

Abstract: Decomposition of methane to produce carbon monoxide-free hydrogen is accomplished using un-supported, nanometer sized, hydrogen reduced, nickel oxide particles made by a precipitation process. A nickel compound, such as NiCl2 or Ni(NO3) is dissolved in water and suitably precipitated as nickel hydroxide. The precipitate is separated, dried and calcined to form the NiO catalyst precursor particles.

Abstract: A process is provided for the production of liquid ferric sulfate from finely-divided ferric oxide, sulfuric acid and water in a reaction system comprising at least one closed reaction vessel at temperatures ranging from about 120° C. to about 150° C. and pressures from about 25 psi to about 70 psi. Iron oxide streams are fed countercurrent to the ferric sulfate reaction product stream and to the sulfuric acid and water feeds. The continuity of the reaction is effected by re-circulating fractions while withdrawing a fraction of the liquid ferric sulfate having a trivalent iron concentration of at least 10% from the reaction vessel. Yield and efficiency are provided by controlling the rate of iron ore, sulfuric acid and specific gravity and by counter current cycling the waste stream from the reaction through the dilution water and use of a polymeric settling agent to remove unreacted iron content from the digester output.

Abstract: The present invention is directed to the microwave treatment of a class of selected metal ores and concentrates, particularly those known as chalcopyrite, in a fluidized bed reactor. The end product is commonly a mixture of copper oxide and copper sulfate, both of which are liquid soluble and directly recoverable by known techniques. The ratio of the oxide-sulfate mixture end product may be controlled by suitable control of microwave parameters.

Abstract: A preferred embodiment of the present invention provides a process for making nickel sulfate by converting nickel metal into nickel sulfate, which may be converted to nickel hydroxide. Nickel metal is dissolved in sulfuric acid and oxygen containing gas is introduced to produce a nickel sulfate solution having nickel sulfate and water as illustrated in the following chemical equation. Ni+H2SO4+½O2?NiSO4+H2O The nickel sulfate is filtered and sulfuric acid is continually added to maintain stoichiometry within a reactor until the nickel metal is dissolved. The sulfuric acid, oxygen containing gas and nickel metal may be heated to facilitate the desired reaction. Then, the nickel sulfate may be utilized to produce nickel hydroxide.

Abstract: A system and method of economically converting a spent first pickling acid solution that contains hydrochloric acid, water and ferrous chloride into a suitable second pickling solution. Sulfuric acid is added to the first pickling acid solution. This produces a regeneration solution. In the regeneration solution, the sulfuric acid reacts with said ferrous chloride and water to produce ferrous sulfate heptahydrate and hydrochloric acid. The regeneration solution is cooled to promote precipitation of the ferrous sulfate heptahydrate from the regeneration solution, therein creating ferrous sulfate heptahydrate crystals and a second pickling acid solution. The second pickling acid solution contains both hydrochloric acid and sulfuric acid. The ferrous sulfate heptahydrate crystals are separated from second pickling solution. The ferrous sulfate heptahydrate is sold commercially and the second pickling acid solution is used to directly pickle ferrous metal.

Abstract: The invention relates to a method for the hydrolytic precipitation of iron as jarosite from a sulphate-containing solution in connection with zinc recovery from zinc calcine. The recovey contains neutral leach, ferrite leach, zinc electrolysis and iron precipitation stages. The ferrite included in the calcine is leached with return acid of the electrolysis after which the iron present in ferrous form is neutralized and routed to an iron precipitation stage, where the iron is oxidised to the trivalent form using an oxygen-containing gas. Also present in the precipitation stage arc Na, K or NH4 ions and jarosite nuclei.

Abstract: In a method of producing ferrous sulfate heptahydrate, ferrous sulfate monohydrate is converted in a crystallization reactor in the presence of water into ferrous sulfate heptahydrate as crystallized product, and water is subsequently isolated from the ferrous sulfate heptahydrate. Ferrous sulfate monohydrate is obtained from a pickling solution containing ferrous chloride, hydrochloric acid and water and reacted in a precipitating reactor in the presence of excess sulfuric acid to form ferrous sulfate monohydrate and hydrochloric acid. The ferrous sulfate monohydrate is then dehumidified and converted in a crystallization reactor in the presence of excess water into ferrous sulfate heptahydrate.

Abstract: A process for the production of liquid ferric sulfate from finely-divided ferric oxide, sulfuric acid and water in a closed reaction vessel at temperatures ranging from about 130.degree. C. to about 150.degree. C. and pressures from about 30 psi to about 70 psi. The reaction time ranges from Four to eight hours and produces liquid ferric sulfate having at least 10% trivalent iron. Yield and efficiency are provided by controlling the specific gravity prior to the reaction and by counter current cycling the waste stream from the reaction through the dilution water and use of a polymeric settling agent to remove unreacted iron content from the digester output.

Abstract: A method of treating residual acid from production of chlorine dioxide is described. The method is characterized in that a compound containing iron is added to the residual acid to react therewith and form a product, which contains iron in trivalent form. As iron compound preferably ferrous sulphate is added, which under oxidation reacts with the residual acid to form ferric salt. Preferably sodium chlorate, sodium hypochlorite, hydrogen peroxide or an oxygen-containing gas is added as oxidant.

Abstract: The invention provides a hydrometallurgical process for treating metal-containing sulfide ores and concentrates, comprising reacting said metal-containing sulfide with concentrated sulfuric acid at a temperature of between about 300° C. and 400° C. in the presence of oxygen to produce a solid metal sulfate product and a gaseous product which is primarily SO3, wherein said metal is selected from the group consisting of iron, copper, zinc, nickel, cobalt and manganese. Said metal sulfate product is then leached with dilute sulfuric acid to form a metal-containing solution, from which the metal values are separated by precipitation at raised H2SO4 concentrations obtained by saturating the solution with the gaseous SO3 from the sulfatization reaction step.

Abstract: The present invention relates generally to a two step solvent extraction circuit to remove impurity metals of zinc and cobalt selectively from a valuable metal of nickel. In order to selectively extract zinc there must be sufficient separation between zinc and cobalt in the cyanex 272 system. Similarly for cobalt and nickel, the separation factor must be of sufficient magnitude to obtain a pure nickel product. The process for the solvent extraction of impurity metals is operated at a temperature exceeding 60° C. being the maximum temperature at which solvent extraction circuits conventionally operate.

Abstract: Apparatus and method for regenerating spent pickling liquor from the acid pickling of a metal are disclosed. Acid pickling of a metal uses a first acid and forms a spent pickling liquor (SPL). A second acid added to the spent pickling liquor, under specific low temperatures produces a metal salt of the second acid. The metal salt of the second acid is crystallized and removed from a regenerated first acid. In one aspect, hydrochloric acid is regenerated from a pickling process for iron or steel, using sulfuric acid as the second acid, and ferrous sulfate heptahydrate crystals are produced. Regenerated hydrochloric acid is recycled to the acid pickling process.

Abstract: The present invention provides an atmospheric acid leaching process for leaching nickel and cobalt from highly-serpentinized saprolitic fractions of nickel laterite deposits that are generally too low in nickel to support economical extraction of their nickel contents by pyrometallurgical processing except under special circumstances, and generally too high in magnesium to be suitable for processing by modern high pressure acid leaching processes employed for treating predominantly limonitic nickel laterites. The process involves leaching the highly-serpentinized saprolitic portion of the nickel laterite ore profile in strong sulphuric acid solutions at atmospheric pressure and temperatures between 80° C. and 100° C., essentially autogenously, to extract at least 90% of its contained nickel content and a large proportion of its cobalt content after leaching reaction times of about one hour or less.

Abstract: A method for the manufacture of a ferric sulfate solution is provided, characterized in that, iron ore containing 30% by weight or more FeOOH as a trivalent iron (Fe3+) is calcined at 200-600° C., and then dissolved in sulfuric acid. A water treatment agent consisting of a basic ferric sulfate solution manufactured by the above mentioned manufacturing method is used as a coagulating agent for water treatment.

Abstract: The invention relates to a method for leaching zinc concentrate in atmospheric conditions in the presence of trivalent iron. It is essential that the zinc concentrate is fed into conditions where in addition to trivalent iron, there are also jarosite nuclei. The sulfuric acid content of the leaching step is maintained within the region 10-40 g/l, and the temperature within the region 80° C.—the solution boiling point, and into the leaching step there is fed oxygen, so that the zinc concentrate is dissolved and the iron is precipitated as jarosite.

Abstract: The invention relates to a method for recovering non-ferrous metals, particularly nickel, cobalt, copper, zinc, manganese and magnesium, from materials containing said metals by converting said non-ferrous metals into sulphates by means of melt and melt coating sulphation, i.e. by a thermal treatment under oxidizing conditions within a temperature range of 400 to 800° C., during which a reaction mixture is formed containing at least one said non-ferrous metal, iron(III)sulphate and alkali metal sulphate, and appropriate reaction conditions are selected to substantially prevent iron(III)sulphate from thermally decomposing to hematite, and finally, said non-ferrous metals are recovered as metallic compounds. In the method of the invention, a process is formed around the melt and melt coating sulphation, which comprises nine steps.

Abstract: Provided herein is a process for treatment of solutions which contain ferrous, ferric and soluble manganese species which process comprises addition of an oxidizing agent to such a solution to cause formation of manganese dioxide particles and adding manganese dioxide seed particles so as to cause nascent manganese dioxide agglomerates formed from the action of the addition of the oxidizing agent on the soluble manganese species to adhere to the manganese dioxide seed particles. By a process according to the invention, it is possible to effectively remove the soluble manganese species as solid manganese dioxide by having effective control over the size of the manganese dioxide particles to enable their subsequent removal using ordinary filtration techniques.

Abstract: The invention relates to a method for the treatment of fluoboric electrolyte resulting from the processes of electro-extraction of metals such as copper and lead comprising a leaching stage with fluoboric acid, in order to recycle said fluoboric acid to be recirculated to said leaching stage devoid of impurities of metals such as Me=Fe, Zn, Ca, Mg, Cd, characterized in that it comprises the stages of: a) treating said fluoboric electrolyte comprising Cu(BF4)2 or Pb(BF4)2 with H2S in order to precipitate CuS or PbS respectively in accordance with the reactions Cu(BF4)2+H2S=>CuS+2HBF4  (1) Pb(BF4)2+H2S=>PbS+2HBF4  (2) thus obtaining a solution of HBF4 containing the fluoborates of said metals Me, said solution being separated, b) treating said Me fluoborates with H2SO4 in accordance with the reaction 2 Me(BF4)n+n H2SO4=>Me(SO4)n+2n HBF4  (3) (where Me=Fe, Zn, Ca, Mg, Cd) it being possible for said sulp

Abstract: The invention relates to a process for recovering metals from used nickel/hydride storage batteries, in which storage battery scrap has been mechanically comminuted and divided into at least a coarse fraction and a fine fraction capable of being treated separately from one another. The process comprises the steps of digesting and dissolving the fine fraction with a mixture of sulfuric acid and hydrogen peroxide, performing a double sulfate precipitation of the rare earths by raising the pH, performing a precipitation of the iron and of the aluminum by further raising the pH, performing a solvent extraction of other metals to separate nickel and cobalt which remain in the aqueous phase from the other metals which are extracted into the organic phase. Optionally, the nickel and the cobalt can be separated from each other and, if desired, the mixed-metal rare earth component which has been recovered can be melted together with cobalt and nickel alloy for the fabrication of new batteries.

Abstract: The present invention provides a method for treating rotary slag containing iron and sodium compounds. The method involves treating the slag in a sulfuric acid solution to convert the iron and sodium within the slag to iron sulfate and sodium sulfate. The iron sulfate (along with substantially all of the heavy metal contaminants) forms a precipitate, while the sodium sulfate remains in solution. The precipitate can then be separated from the solution.

Abstract: The invention relates to a method for recovering nickel in one and the same process from two pyrometallurgically produced nickel mattes, one of which contains a remarkable percentage or iron. The leaching of iron-bearing nickel matte is carried out in one step by conducting solution from the leaching cycle of a less iron containing matte into the leaching of a more iron containing matte at a stage where the iron of the less iron containing matte is in soluble form. The iron contained in the mattes is advantageously precipitated as jarosite and the solution created in the leaching of the more iron containing matte is conducted back into the leaching cycle of the less iron containing matte.

Abstract: The invention relates to a process of preparing ferric sulfate by forming a slurry which contains ferrous sulfate and sulfuric acid, the slurry containing bivalent iron in both the solution phase and the solid phase, and by oxidizing this slurry to form a ferric sulfate slurry. When so desired, the obtained ferric sulfate slurry is solidified to form solid ferric sulfate. The obtained ferric sulfate may, as such or dissolved in water, be used for the treatment of waste waters or for preparing pure tap water.

Abstract: Ferric sulfate is produced by treating ferric ammonium sulfate, ammonium jarosite or a similar iron complex with nitric acid. The ferric ammonium sulfate or ammonium jarosite can be formed by treating a sulfuric acid leaching solution, e.g., a solution used to leach zinc or copper ore concentrate, with a solution of ammonium nitrate. Thereafter, upon addition of dilute nitric acid at a temperature of about 60.degree. C., ferric sulfate forms and is recovered.

Abstract: Method to prevent the exhaustion of acid copper plating baths (12) and to treat sewage or sludges (20) containing copper in an ionic form so as to recover metallic copper (39), the method including the addition (11) of a compound which keeps the concentration of iron below a critical value (for instance, 60 grs/lt. ), the compound causing precipitation of iron in the form of ferrous sulphate and thus preventing the co-deposition of crystals of ferrous sulphate and copper sulphate with a possible incorporation of organic impurities such as stearates (35) present in the acid copper plating baths (12).

Abstract: Disclosed herein is a method for treating a spent copper-refining electrolyte to remove impurities such as copper (Cu), arsenic (As), antimony (Sb), bismuth (Bi), nickel (Ni) and the like by using a hydrogen sulfide gas. The method comprises the steps of: (a) blowing a hydrogen sulfide gas into the spent electrolyte to precipitate copper sulfide (CuS); (b) blowing air into the coprecipitates solution obtained in the above step (a) to oxidize arsenic, bismuth and antimony thereby redissolving them into the solution, and the solution is subjected to solid-liquid separation to separate copper sulfide from the liquid; (c) blowing a sulfur dioxide gas into the copper-depleted liquid to reduce arsenic, bismuth and antimony and blowing a nitrogen gas to purge the remaining sulfur dioxide gas; (d) blowing a hydrogen sulfide gas to precipitate arsenic, bismuth and antimony in the form of sulfides and blowing a nitrogen gas to purge the remaining hydrogen sulfide gas and separating arsenic sulfide (As.sub.2 S.sub.

Abstract: A process is disclosed for recovering zinc, lead, copper and precious metals from zinc plant residue, said process comprising leaching the residue with return zinc spent electrolyte, neutralizing residual acid and reducing ferric iron in the solution by addition of zinc sulphide concentrate in the presence of a limited quantity of oxygen, flotation of the resulting slurry to separate unreacted zinc sulphide, treatment of flotation tailings with sulphur dioxide and elemental sulphur to further leach iron, zinc and impurity elements and precipitate copper, flotation of the resulting slurry to separate a copper sulphide concentrate, thickening, filtering and washing of the flotation tailings followed by addition of lime and sodium sulphide to activate lead sulphate and flotation of a lead concentrate from the residue.

Abstract: A method for the recovery of copper from copper-containing materials, for example, scrap, ores or dust. An aqueous cupric tetrammine sulfate lixiviant is contacted with the copper-containing material to produce a leachate containing cuprous, nickel, and zinc ions, ammonium sulfate and free ammonia. Copper can be recovered from the leachate by electrolysis. Nickel and zinc can be precipitated from the resulting spent electrolyte by oxidizing substantially all of the cuprous ions in the copper ammine sulfate solution to cupric ions and lowering the pH of the solution to a range from about pH 7.5 to about pH 8.0 in order to form a precipitate. Alternatively, copper sulfate can be added to the cupric ammine sulfate-containing solution in order to form nickel and/or zinc containing precipitate.

Abstract: A process for recovering zinc/rich and iron-rich fractions from the baghouse dust that is generated in various metallurgical operations, especially in steel-making and other iron-making plants, comprises the steps of leaching the dust by hot concentrated sulfuric acid so as to generate dissolved zinc sulfate and a precipitate of iron sulfate, separating the precipitate from the acid by filtration and washing with a volatile liquid, such as methanol or acetone, and collecting the filtered acid and the washings into a filtrate fraction. The volatile liquid may be recovered distillation, and the zinc may be removed from the filtrate by alternative methods, one of which involves addition of a sufficient amount of water to precipitate hydrated zinc sulfate at 10.degree. C., separation of the precipitate from sulfuric acid by filtration, and evaporation of water to regenerate concentrated sulfuric acid.

Abstract: According to the method of the invention, at least one or several of the metals nickel, cobalt and copper can be selectively precipitated as sulphide by aid of elemental sulphur from aqueous solutions containing other metals such as zinc. The temperature of the reaction is above the melting point of sulphur. The precipitation is carried out with a pH value below 2. The metals to be precipitated can be present in the solution either as oxides or sulphates. If the metals are sulphates, the sulphide of at least one of the metals is prepared to crystal seeds in the solution before precipitation.

Abstract: The invention relates to a process for recovering non-ferrous metal values such as nickel, cobalt, copper, zinc, manganese and magnesium from material containing said metals, by converting the non-ferrous metal values into sulphates by using melt and melt coating sulphation and recovering them as metal compounds by a process entity based on a melt and melt coating sulphation.

Abstract: Aqueous effluent solutions containing metal cations may be treated with an extractant comprising an organophosphinic acid, a di-2-ethylhexyl phosphoric acid and/or an aliphatic amine to selectively separate chromium, nickel, cobalt, copper and lead cations from the aqueous solution. Typical extraction techniques include liquid-liquid extraction employing either mixer settlers or columns, liquid membrane extraction and selective supported membrane extraction.

Abstract: The invention relates to a process for the recovery of metal values contained in a ferric gangue.The process comprises the following stages:(a) dissolution of the metal values from the ferric gangue with sulphuric acid;(b) recovery of the metal value or values by a method which is known per se,(c) evaporation of the acid ferric solution resulting from stage (b) so as to increase the acidity to a value of between about 50 and 100%,(d) crystallization from this solution, at a temperature of between -10 and 50.degree. C., of a hydrated iron sulphate of formula Fe.sub.2 (SO.sub.4).sub.3.9H.sub.2 O.Application to the recovery of strategic metals.