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: Process for purifying an iron containing zinc sulfate solution which comprises precipitating iron from said solution as a slurry in at least one of the following forms at a pH which is maintained lower than 4: basic sulfate, jarosite or goethite; filtering said slurry on a planar horizontal filter and forming a cake on said planar filter; washing the cake directly on the planar filter with water supplied onto the cake without forming a newslurry with washing water and thus freeing the cake from water soluble zinc and copper compounds promptly before hydrolysis thereof insolubilizes said compounds as basic sulfates, whereby the solid residue in the cake does not contain substantially more insoluble zinc content than it contained in the slurry being fed to the filtration.

Abstract: A process for recovering nickel from an impure nickel compound which contains a major proportion of nickel values and a minor proportion of other metal values which are relatively soluble in ammoniacal ammonium sulphate solution, and a minor proportion of nickel values and other metal values which are relatively insoluble in the solution. The impure nickel compound is treated with ammoniacal ammonium sulphate solution so that the relatively soluble nickel and other metal values are dissolved in the solution with the relatively soluble nickel values being dissolved substantially as nickel diammine sulphate, and so that the relatively insoluble nickel and other metal values form an undissolved residue.

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: The red mud by-product of the Bayer process by which aluminum oxide is reed from bauxite as an aluminate, is digested with concentrated sulfuric acid or with sulfur trioxide gas to produce sulfates that can be leached out to the resulting mass with water. The solution is then heated at a pH of 1 to precipitate titanium oxide hydrate by hydrolysis. The remaining sulfates of the solution are then obtained in solid form by evaporation, or by precipitation with acetone, and the solid is then roasted to convert the aluminum and iron to the oxide. After leaching out the sodium sulfate with water, the aluminum and iron oxide are separated by the Bayer process, which works in this case even though x-ray diffusion patterns show that the aluminum oxide is mainly .alpha.Al.sub.2 O.sub.3.

Abstract: Process for quantitatively converting non-ferrous metals chosen from the group consisting of copper, nickel, cobalt, vanadium, and manganese in an ore concentrate to soluble sulfates and simultaneously convert the ferrous values in the ore to insoluble oxides. The process comprises roasting finely divided ore particles at a temperature in excess of 650.degree. C. in the presence of a roaster gas comprising at least a stoichiometric amount of oxygen and at least 1% SO.sub.2. The roasting is performed in the presence of a sufficient amount of a mixture of salts to allow the formation of a liquid coating on the ore particles. In a preferred embodiment, the mixed salt which forms the liquid coating comprises Na.sub.2 SO.sub.4 and K.sub.2 SO.sub.4 with the ratio of sodium to potassium being between 1.0 and 2.0.

Abstract: A process and a product formed thereby for the recovery of chromium values from aqueous solutions (e.g., waste liquors) comprises contacting an acidic solution containing sulfate ion and trivalent chromium ion with at least about 4 molar equivalents of MgO or Mg(OH).sub.2 per 3 molar equivalents of trivalent chromium in addition to the amount required to neutralize the free acid to a pH of about 4 to form an amorphous, dense solid, grainy, easily settleable, trivalent chromium-containing precipitate in an alkaline solution according to the equation: 3Cr.sub.2 (SO.sub.4) + 8 MgO .fwdarw.Cr.sub.2 (OH).sub.4 SO.sub.4 .multidot. 4Cr(OH).sub.3 .multidot. 4H.sub.2 O + 8 MgSO.sub.4. The trivalent chromium-containing product can be readily separated from the water and is a useful source of chromium for subsequent processing. The water remaining after separation of the precipitate contains less than 0.5 mg/l chromium.

Abstract: Production of titanium dioxide which is characterized by recovery of reusable H.sub.2 SO.sub.4, highly pure Fe oxide and hydroxide and fractional recovery of Mn, V and Cr, etc., from FeSO.sub.4. nH.sub.2 O and waste acid of 20 - 40% H.sub.2 SO.sub.4 containing abundant heavy metallic ions, which are by-produced in the production of TiO.sub.2 by dissolution of Ti raw materials such as ilmenite, steel production slag, such as electric furnace slag, convertor slag with H.sub.2 SO.sub.4.

Abstract: A process for the preferential removal of soluble manganous ions from a metal bearing solution, particularly a zinc sulfate solution to be subjected to electrolysis for the recovery of zinc, comprising treating said solution with an oxidant capable of oxidizing soluble manganous ion to insoluble and filterable gamma-manganese dioxide at a temperature and for a time sufficient to precipitate at least a portion of the manganese present in said solution as gamma-manganese dioxide, said oxidant being in an amount of from about 130% to 150% of the theoretical amount required for substantially total manganese removal from said solution, and separating said precipitate from said solution.

Abstract: A finely divided product containing Ni and Fe is dissolved in a sulfate-containing solvent in at least two stages and in the presence of an alkali metal and an oxidant for preciptating the Fe as alkali jarosite while Ni remains in solution which is subjected to an after-treatment. Similar processes can be used to separate cobalt and/or chromium from products containing either or both of these metals as well as iron.

Abstract: Process for control of SO.sub.x emissions from copper smelter operations involving pyrometallurgical reduction of copper ores to elemental copper in which the gases from reverberatory furnaces, roasters, and/or converters are scrubbed with a sodium alkali sorbent to produce sodium sulfate and sulfite wastes. The cleaned flue gases are exhausted to the atmosphere. The waste sodium sulfate/sulfite material is then reacted with excess acid from the smelter acid plant and ferrous ion-rich barren solution from the associated cement copper operations to produce co-precipitated double salts of sodium ferric hydroxy-disulfates and/or sulfites (SFH), having low water solubility and being suitable for landfill type disposal without posing serious water pollution problems. This disposes of the sodium sulfite/sulfate waste materials from the air pollution control process and also strips the barren solution of iron prior to its recycle to heap or dump leaching operations.

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: A method is provided for processing raw manganese nodules for the selective recovery of metal values of nickel, copper, cobalt and zinc contained therein by hydrometallurgical means. The raw nodules are suspended in water or dilute wash solution to form a suspension. The suspension and sulfuric acid are charged to a pressure vessel to provide a solid-liquid suspension of nodules and leach solution. The solid-liquid suspension of nodules and leach solution is heated in the pressure vessel to a temperature between about 150.degree. C and about 300.degree. C to cause the nickel, copper, cobalt and zinc to be selectively leached from the nodules into the leach solution to form a metal rich leach solution containing these metals and a residue, with the solid-liquid suspension having a sulfuric acid content of less than 35 g/l upon completion of the leaching. The metal rich leach solution containing nickel, copper, cobalt and zinc is separated from the residue.

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).

Abstract: The process disclosed is for separation of iron from sulphuric acid acidified sulphate solutions containing zinc to be recovered and iron, the process comprising reacting such a solution at atmospheric pressure and at temperatures of 60 to 100.degree.C., preferably 85.degree.-95.degree.C., with a precipitating agent, in the form of a slurry or solid material containing Fe.sub.2 O.sub.3 or Fe(OH).sub.3 as an essential component. The precipitating agent optionally may be "red mud," a byproduct from the decomposition of bauxite. The precipitating agent may contain or have added thereto Al.sub.2 O.sub.3 and TiO.sub.2 which also contribute to the hydrolysis of the solution. The acid strength of the solution is adjusted to a pH of 1.0 - 2.5, preferably 1.4 - 1.7 by controlling additions of the said precipitating agent to the sulphate solution.

Abstract: According to the process described, non-ferrous metal values, particularly nickel, copper and/or cobalt, are extracted from metallurgical intermediates, such as matte and speiss, by reacting the material under oxidizing conditions at a pH of about 4.5 to 6.5 with an ammonia free aqueous solution containing ammonium sulphate, sodium sulphate and/or nickel sulphate. The reaction-products of this operation are then mixed with sulphuric acid under ambient conditions to decrease the pH to about 3-4.5 and to dissolve the non-ferrous metals in the solution which is then separated from the undissolved residue. The process is particularly useful in treating intermediates containing precious metals in that the precious metals are substantially completely recovered in concentrated form in the undissolved residue.

Abstract: Metal can be recovered from metal-containing waste by means of liquid extraction processes. The waste is leached with sulphuric acid. The resulting metal sulphate solution is contacted with an organic solution of a reagent, so as to extract iron and zinc to the organic solution. The organic solution is washed with sulphuric acid in two steps, viz. with weaker acid in the first step, so as to transfer zinc to the washing solution, and with stronger acid in the second step, so as to transfer iron to the washing solution. Zinc and iron have now been separated, and are recovered from the washing solutions in known ways, for example by crystallization. If the waste contains other metals, in addition to iron and zinc, additional selective liquid extraction processes are added, before or after the iron-zinc-extraction.

Abstract: A hydrometallurgical method of recovering zinc, copper and cadmium from their ferrites so that the ferrites are treated under atmospheric conditions in sulphuric acid bearing solution in the presence of potassium-, sodium- or ammonium-ions, is disclosed, in which the treatment takes place in one stage under such conditions that the non-ferrous metals, zinc, copper and cadmium, contained in the ferrites are transferred as sulphates to the solution and the iron is converted in the same stage to a solid basic iron salt by adjusting the sulphuric acid or ferric sulphate addition to be equivalent with regard to the ferrite amount fed into this stage and by adjusting the temperature to 80.degree. - 105.degree.C, preferably to 95.degree. - 105.degree.

Abstract: A continuous process for producing granular ferric sulfate significantly reduces manufacturing time, increases product output through the elimination of the curing stage employed in batch-type processes, and because of reduced heat requirements consumes less energy during the final drying phase. At the initial aqueous phase of the process a low water-containing slurry or dispersion of iron oxide is reacted with only a portion of the total sulfuric acid required in the process to produce a ferric sulfate-containing slurry having unreacted iron oxide. That quantity of acid withheld from the aqueous phase is employed at the time of agglomeration of the ferric sulfate-containing slurry. By delaying use of the remaining acid to a later step in the process the heat of reaction generated from the conversion of the unreacted iron oxide in the slurry may be utilized for completing the reaction and for drying the granules. Thus, drying time is shortened and the consumption of supplemental fuel is greatly reduced.

Abstract: The jarosite process of electrolytic refining of zinc is extended and improved by treating the jarosite residues to recover valuable by-products. The wet jarosite residue is acidified with sulphuric acid from the refining process acid plant to redissolve the iron sulphate, producing a liquid containing dissolved plant nutrients. A substantial part of the iron sulphate is removed by fractional crystallization and the mother liquor is heated to drive off water and produce dry nutrient sulphates to which super phosphate, formed by treating phosphate rock or bone with acid from the refinery acid plant to produce a final enriched fertilizer product.The iron sulphate solution may be heated to drive off water and roasted to produce iron oxide. If desired, the iron oxide may be reduced to metallic iron.Water and sulphur products produced in the treatment of the jarosite residues are recovered and integrated into the refinery plant circuits.