Abstract: A hydrometallurgical process for producing zinc oxide from an aqueous solution containing zinc ions is provided. The process comprises the steps of contacting a zinc solution with an insoluble organic solvent selective to the extraction of zinc and thereby produce a zinc-loaded organic solvent. The zinc is then stripped from the zinc-loaded organic solvent with a solution of nitric acid to form a solution of zinc nitrate. The zinc nitrate solution is subjected to thermal hydrolysis at an elevated temperature in the presence of pressurized water vapor, the temperature being at least sufficient to decompose the zinc nitrate to zinc oxide which is thereafter recovered.

Abstract: A process for extracting metal values especially zinc values from aqueous solutions of metal salts which comprises contacting the aqueous solution with an organic phase comprising a compound of the formula: ##STR1## wherein each of R.sup.1, R.sup.2, R.sup.3 and R.sup.4, independently, represents an optionally substituted hydrocarbyl or hydrocarbyloxy group or R.sup.1 and R.sup.2 together with the attached phosphorus atom and/or R.sup.3 and R.sup.4 together with the attached phosphorus atom form a 5- to 8-membered heterocyclic ring.

Abstract: A process for removing mercury or other metal impurities from elemental sulphur contaminated therewith includes mixing such elemental sulphur in a molten state with an aqueous sulphide solution or an aqueous solution of sufficiently high pH which reacts with elemental sulphur and forms a sulphide solution to cause extraction of mercury or other metal contaminants from the elemental sulphur into the aqueous sulphide solutions, and separating the aqueous sulphide solution containing mercury or other metal contaminants from the molten elemental sulphur to provide an elemental sulphur product substantially free from mercury and other metal contaminants.

Abstract: A process for extracting metal values especially zinc values from aqueous solutions of metal salts which comprises contacting the aqueous solution with an organic phase comprising a compound of the formula: ##STR1## wherein each of R.sup.1, R.sup.2, R.sup.3 and R.sup.4, independently, represents a substituted hydrocarbyl or hydrocarbyloxy group or R.sup.1 and R.sup.2 together with the attached phosphorus atom and/or R.sup.3 and R.sup.4 together with the attached phosphorus atom form a 5- to 8-membered heterocyclic ring.

Abstract: A process for recycling a zinc phosphating system sludge comprising forming a mixture of the sludge with water and phosphoric acid. The mixture is formed at an elevated temperature and a pH of between 1.5 and 2.4. The sludge substantially dissolves in the mixture and iron phosphate precipitates out. The resultant liquid comprises a substantially zinc ion and phosphate ion solution suitable for use as a make-up feed in zinc phosphating system.

Abstract: A substantially 100% active aqueous solution of one or more phosphonocarboxylic acids and one or more hydroxides, wherein the solution has a slightly alkaline pH. In an alternate embodiment, a dry, free flowing mixture comprising one or more phosphonocarboxylic acids, calcium chloride fines which, on average, are a dihydrate, and hydroxide is disclosed.

Abstract: It has been discovered that relatively large cyclic and open chain carbonates are extremely efficient in the selective extraction of metal ions, such as gold, silver, platinum and mercury from aqueous solution without the need for a potentially hazardous, organic solvent or use of a corrosive salt, such as NaCl. For example, 1,2-decane carbonate extracted >99.9% mercury, 99.76% gold, 97.5% silver and 79.0% platinum. The homologous 1,2-dodecane carbonate was found to extract 99.9% gold and silver from aqueous solution and 95.8% platinum. Didecyl carbonate extracted 77% gold from aqueous solution. The method of this invention is simpler than prior techniques and eliminates the need for potentially hazardous solvents (toxic, flammable and environmentally unfavorable) and corrosive additives, such as salt, NaCl, used as a salting agent in prior methods.

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: The present invention describes a method of making metal stannates by reacting a solid metal oxide, hydroxide or carbonate with an aqueous stannate solution and recovering the precipitated metal stannate, the solid component being added in an amount which is stoichiometrically not substantially more then the amount of tin.

Abstract: A method of removing or of accumulating heavy metal ions from an aqueous solution by contacting the latter with an ethylene copolymer, in which a copolymer of ethylene with (meth)acrylic acid and a (meth)acrylate is used, in which the carboxyl groups may be neutralized by metal ions to an extent of 100% or less.

Abstract: A process for fixing elemental mercury (Hg.degree.) in a spent molecular sieve desiccant is disclosed. The process includes isolating gspent molecular sieve desiccant containing elemental mercury, and contacting the spent desiccant in a dilute aqueous solution of an alkaline metal salt. The reaction traps the mercury within the spent desiccant as an insoluble heavy metal salt. The alkaline metal salt can include, for example, sodium thiosulfate (Na.sub.2 S.sub.2 O.sub.3), sodium polysulfide (Na.sub.2 S.sub.x), or potassium peroxomonosulfate (KHSO.sub.5). The reaction with any of these aqueous solutions acts to fix the elemental mercury (Hg.degree.) as a mercury compound within the solid desiccant. If sodium thiosulfate or sodium polysulfide is utilized, then the process also includes introducing hydrochloric acid (HCl) in a suitable quantity to liberate sufficient elemental sulfur to react with the elemental mercury (Hg.degree.) to form an HgS salt. The formation of HgS fixes the elemental mercury (Hg.degree.

Abstract: A process and system for disposing of fluorescent lamps and reclaiming components therefrom which includes the removal of the lamp ends and the washing of the lamp envelopes, or crushed lamp envelopes, with wash water to remove mercury and phosphors therefrom. The wash water is then screened to remove glass fragments, and phosphors and mercury present are removed therefrom by decantation and centrifugation. The residual wash water is thereafter treated with a reducing agent to precipitate remaining mercury, and the precipitate is eliminated by decantation and filtration. Additional mercury and cadmium present in the wash water is thereafter removed by treatment with a cationic exchange resin, and the wash water is recycled along with the other water streams produced during the processing.

Abstract: A method for neutralizing a sulfuric acid solution containing predominantly Zn ion, comprising adding, to the sulfuric acid solution, at least one compound selected from the group of chlorine-containing compounds of Na ion, K ion, Mg ion, Ca ion, and NH.sub.4 ion in an amount at least chemically equivalent to SO.sub.4 ion contained; and then bringing the sulfuric acid solution into contact with an organic solvent composed of one or more species selected from the group of oxygen-containing organic solvents and alkylamine organic solvents to extract Zn ion from the sulfuric acid solution as a chloride complex to the organic solvent. The sulfuric acid solution after extraction of Zn ion is further treated by addition of an oxidizing agent or by an electrochemical means to convert Fe.sup.2+ into to Fe.sup.

Abstract: A process for the hydrometallurgical recovery of metal value, particularly copper, from copper-containing sulphide materials in which the material is conventionally ground and reacted with a solution containing less than 3 moles per liter of chloride ion, and optionally as little as 15 g/liter, together with sulphate ions with continuous oxygen injection and vigerous agitation. The reacting may be carried out at a pH in the range of 0.5-4, at moderate pressure as low as atmospheric pressure and at a moderate temperature below the boiling point of the solution such as 85.degree. C.

Abstract: An improved method for selectively rcovering Ge from acidic solution containing Ge and typically Zn, As, Cd, Sb, In, Cu and Fe (II) by multistage, countercurrent liquid-liquid extraction is described. The extractant used in the organic phase is an oxime, for example, 5,8-diethyl-7-hydroxy-6-dodecanone oxime, mixed with at least one alkylphosphoric acid, for example either di-2-ethylhexyl phosphate alone or admixed with mono-2-ethylhexyl phosphate, dissolved in a hydrocarbon diluent. This mixed system shows better efficiency and selectivity for germanium than known systems using either oximes or alkylphosphoric acids separately.

Abstract: The invention relates to a process for preparing a mercury collecting solid mass containing a carrier and copper, at least partly as copper sulfide, comprising the following steps of:(a) incorporating with the carrier at least one copper compound other than a sulfide,(b) optionally roasting said carrier,(c) incorporating therewith at least one organic polysulfide, and(d) thermally treating the resultant mass, in non-oxidizing atmosphere, under gas scavenging.The invention also concerns a regenerating process for a mercury recovery mass, containing a carrier, and copper, at least partly as copper sulfide, comprising incorporating with said mass, after a decrease of its mercury recovery efficiency and after removal of at least a part of its mercury content, an organic polysulfide, and finally subjecting it to a thermal treatment, in non-oxidizing atmosphere, under gas scavenging.

Abstract: Improved processes for the removal from solution of multi-valent alkaline earth metal and/or heavy metal cations are taught, having excellent combinations of cation capacity and resistance to bead breakage. The processes use specified polymer resin beads functionalized with chelating functionalities such as alkylaminophosphonic moieties or iminodiacetic acid moieties. The beads are prepared by the specified process to have a decreased amount of cross-linking in the shell area as compared to the core. An additional aspect of the invention is an improved gel-type chelating resin having core/shell morphology and alkylaminophosphonic functional groups which is found to exhibit surprising combinations of dynamic capacity, osmotic shock resistance, and physical strength. This chelating resin has been found to be very suitable for the removal of calcium from brine solutions prior to the use of such solutions in membrane electrolysis cells of chlorine production.

Abstract: A method for recovery of metal and cyanide from plating baths and rinse waters includes formation of hydrogen cyanide by acid treatment of such solutions, followed by HCN removal through diffusion across a microporous membrane. The method is applicable in a system wherein soluable metal cyanides and metal cyanide complexes are concentrated through use of a basic anion exchange system. Free hydrogen cyanide is released from the anion exchange system by means of an acid regenerant. In a preferred application of the invention, HCN, once having diffused through the microporous membrane, is neutralized with sodium hydroxide, to form a sodium cyanide solution that can be returned to a plating bath.

Abstract: A process for the common or simultaneous separation of arsenic, antimony, bismuth and iron from electrolyte solutions of valuable metals by solvent extraction and subsequent recovery of the contaminating elements, which process is characterized in that aqueous mineral-acidic electrolyte solutions of valuable metals are admixed with a sparingly water soluble organic solvent containing at least one hydroxamic acid, the aqueous and organic phases are thoroughly mixed, the contaminating elements arsenic, antimony and bismuth are precipitated from the organic phase by direct sulfide precipitation, the sulfides are separated, and the extracted iron is subsequently reextracted with a water soluble iron-complexing agent into an aqueous phase and recovered.

Abstract: This invention relates to a method of recovering non-ferrous metal sulfides from a metal ore which comprises subjecting the metal ore, in the form of an aqueous pulp, to a froth flotation process in the presence of a flotating amount of a flotation collector wherein the collector comprises a compound which corresponds to one of the formulas ##STR1## wherein R.sup.1 is alkyl, aryl or aralkyl group wherein the aryl and aralkyl can be substituted with a halo or alkyl moiety;R.sup.2 is alkyl, aryl or aralkyl group wherein the aryl or aralkyl can be substituted with a halo or alkyl moiety;R.sup.3 is aryl or aralkyl unsubstituted or substituted with a halo or alkyl moiety;R.sup.4 is alkyl, aryl or aralkyl group wherein the aryl or aralkyl can be substituted with a halo or alkyl moiety; with the proviso that at least one of R.sup.1 and R.sup.2 must be aryl or aralkyl unsubstituted or substituted;under conditions such that the metal sulfide values are recovered in the froth.

Abstract: Disclosed is a composite body comprising amorphous and porous silica or silica-alumina and a layer of an aluminum-containing phylosilicate formed on surfaces of primary particles of the silica or silica-alumina. This composite phylosilicate is obtained by reacting a water-soluble silicate, a water-soluble zinc salt or magnesium salt and a water-soluble aluminum salt or aluminate in an aqueous medium containing a sol or gel of silica or silica-alumina. This composite phylosilicate has a large specific surface area and a large pore volume and has both the properties of a solid acid and the properties of a solid base.

Abstract: A mixture of mercury and red phosphorus obtained by flowing an aqueous solution having at least one mercury salt dissolved in it through a layer of granular red phosphorus in a column arranged in upright position and provided, close to its lower end, with means supporting the layer of red phosphorus, is separated into its constituents. To this end, fluidizing matter is forced from below under pressure over a period of 5-30 minutes through the said means and layer of red phosphorus thereon, the mercury/red phosphorus-mixture covered with solution and provided with flow deflecting paths becoming lifted up; mercury dropping from the mixture so lifted is collected over a period of 5-30 minutes on the supporting means; fluidizing matter is forced from above under pressure over a period of 1-20 seconds into contact with the said mixture; and the mercury running down from the supporting means is collected. Apparatus for carrying out the process.

Abstract: A material is, herein disclosed for collecting radionuclides and heavy metals that comprises an acrylic fiber element having MnO.sub.2 and/or ferrocyanide compound of the formula K.sub.2 M.sup.II [Fe(CN).sub.6 ] (wherein M.sup.II is a divalent metal such as cobalt, zirconium, zinc or nickel) supported thereon. The material of the present invention is used in collecting and concentrating radionuclides present in liquid radioactive wastes discharged from nuclear power plants and other facilities using radioisotopes such as hospitals and non-destructive testing laboratories. The material is also used in collecting and concentrating radionuclides and heavy metals present in the seawater, rivers and industrial waste-water.

Abstract: A crystalline zinc silicate mineral of the sauconite, hemimorphite or willemite type is prepared by subjecting an acid-treated product of a clay mineral and an oxide or hydroxide of zinc or a compound capable of forming this oxide or hydroxide under reaction conditions to a hydrothermal treatment. This crystalline zinc silicate mineral has a fine and uniform particle size and is excellent in the pigmenting characteristics.

Abstract: Metal ions are reduced from a higher to a lower oxidation stage using ferrophosphorus as the reductant.

Abstract: A method for preparing a .sup.195m Au-containing liquid is provided. In the method, .sup.195m Hg is adsorbed on an adsorption agent and then the daughter radioisotope .sup.195m Au is eluted from the adsorption agent with an eluant containing a gold-complexing agent. The adsorption agent comprises a mercury ion-binding material having a substantially stronger adsorption affinity for mercury ions than for gold ions.Also disclosed are a radioisotope generator capable of producing a .sup.195m Au-containing liquid and a process for conducting a radiodiagnostic examination on a warm-blooded animal using a .sup.195m Au-containing liquid.

Abstract: A method for the purification of gases containing mercury and simultaneous recovery of the mercury in metallic form by a process where primarily a reaction takes place between metallic vapory mercury and mercury (II)-chloride compounds in solution in a liquid phase, during which the formation and deposition of only slightly soluble Hg (I)-chloride (calomel) occur, the deposited calomel being oxidized to easily soluble Hg (II)-chloride compounds by the adding of chlorine, and metallic mercury and at least some of the chlorine used being recovered by electrolysis of said formed Hg(II)-chloride.

Abstract: This invention relates to the development of a viable metallurgical process capable of treating low grade concentrates, bulk concentrates, dirty concentrates, or ore directly for the recovery of non-ferrous metals such as zinc, lead, copper, and precious metals and accordingly is significant to the development of massive fine grained sulphide ore bodies found throughout the world. The process involves the consecutive steps of sulphatizing roasting in a fluidized bed reactor, a two stage leach, metal recovery from solution by conventional processes such as electrowinning and precipitation, and recycling of residue wash waters and leach liquors containing high concentrations of iron and minor impurity elements to the roaster or a spray dryer for thermal decomposition. Simple and efficient rejection of iron from the circuit to residue as stable hematite is the net result of the recirculation and thermal decomposition.

Abstract: A membrane-based solvent extraction system is used to separate zinc from plating wastes and to recycle the concentrated zinc solution to the plating bath. Di-2 ethylhexylphosphoric acid (DEHPA) is used as an organic carrier, and an acid or salt solution is used as a stripping agent in this process.

Abstract: This invention relates to a process for making the chloride of a metal from the sulfide of said metal in the absence of air and for a metal selected from copper, iron, lead, zinc, silver and gold. The process consists of three broad steps. First, forming an intimate mixture of finely divided sulfides of the metals with finely divided chlorides, the latter being in an anhydrous state. Second, heating the mixture to a temperature at which there is a rapid reaction converting the metal sulfides to chlorides and elemental sulfur in the state of a solid aggregate mixture. Third, recovering the formed metal chlorides from the aggregate mixture by conventional means.

Abstract: A coating comprising elemental silicon is electrodeposited on a substrate from an aqueous medium. The plating bath is a solution of what is described as one or more metal hydrides. The metal hydrides of the present invention are provided by combining stoichiometric amounts of metal, alkaline metal hydroxide and water in a preselected proportion by mole percent. The particular proportion is a function of the particular metal. A hydride concentrate is provided which is used in aqueous solution to provide a plating bath.

Abstract: A process for selective liquid-liquid extraction of germanium from an aqueous acidic liquor containing, besides germanium, at least one other metal selected from the group which comprises cadmium, zinc, cobalt, iron, arsenic and nickel. This process includes extracting germanium from said aqueous liquor by contacting said liquor with an organic medium containing a diluent and an extractant, said diluent being immiscible with said aqueous liquor. The major part of germanium passes from said aqueous liquor to an organic phase which is subsequently submitted to a stripping step by contacting with an alkaline medium, with formation of an aqueous phase containing the major part of germanium from said aqueous liquor.

Abstract: The disclosure relates to a process for removing foreign components, especially zinc, from the product cycle during the production of yellow phosphorus inside and electrothermal furnace. To this end, the disclosure provides for molten ferrophosphorus and a calcium metasilicate slag and also a dust-containing gas mixture consisting essentially of carbon monoxide and phosphorus in vapor form to be taken from the furnace charged with phosphate pellets, coke and gravel. After electrostatic separation of the dust from the gas mixture, the dust is water-treated and made into a dust suspension. Crude phosphate is granulated on a granulating means using a mixture of dust suspension and binder which preferably is a clay suspension. The granulated material is calcined on a sintering device and made into phosphate pellets. A portion of the molten slag taken from the electrothermal furnace is allowed to solidify and the solidified slag is ground.

Abstract: Insolubilized poly(maleic anhydride) is disclosed for use in a method of removing heavy metals, particularly lead, from aqueous media.

Abstract: A process for the separation of heavy metal components, especially of compounds of cadmium, mercury and lead, from crude phosphoric acid obtained according to the Odda process, which comprises adjusting this crude phosphoric acid with ammonia to a pH of from 0.5 to 1.5, contacting it subsequently with a diorganyl-dithiophosphorus compound and an adsorbent, and then separating the acid from the absorbent containing the heavy metal impurities.

Abstract: In the roasting (oxidation) of mixed zinc sulphide/lead sulphide concentrates, to give an oxidic product for reduction, improved sulphur elimination and reduced lead volatilization are achieved by mixing 2-20% by weight of zinc oxide with the mixed sulphide materials, forming pellets of 2-15 mm diameter and roasting these under controlled oxidation conditions, firstly at a lower temperature and then at a higher temperature; preferably at 850.degree.-950.degree. C. for the first stage and at 950.degree.-1050.degree. C. for the last stage.

Abstract: A process for recovering non-ferrous metal values from their ores, minerals, concentrates, oxidic roasting products, or slags by sulphating said starting material using a mixture comprising iron (III) sulphate and alkali metal- or ammonium sulphate as a reagent.

Abstract: Germanium is separated from an aqueous solution by means of a substituted 8-hydroxyquinoline extractant.Re-extraction of germanium from the extractant is carried out above 40.degree. C. and with an organic phase: aqueous phase volume ratio less than 1, whereby obtaining a high re-extraction yield.

Abstract: Improvement in electrowinning manganese dioxide, or zinc in which the relative concentration of manganese or zinc ions to impurities is enhanced by selectively extracting manganese or zinc ions from a bleed taken from the electrowinning feed stream with an organic extractant, while rejecting impurities, stripping the loaded organics with spent electrolyte, and recycling loaded strip to the electrowinning feed. Stripped organic may be regenerated with an alkaline agent such as calcium oxide or magnesium oxide prior to recycle, and pH may be controlled during extraction by the same means.

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: A method for preparing a .sup.195m Au-containing liquid is provided. In the method, .sup.195m Hg is adsorbed on an adsorption agent and then the daughter radioisotope .sup.195m Au is eluted from the adsorption agent with an eluant containing a gold-complexing agent. The adsorption agent comprises a mercury ion-binding material having a substantially stronger adsorption affinity for mercury ions than for gold ions.Also disclosed are a radioisotope generator capable of producing a .sup.195m Au-containing liquid and a process for conducting a radiodiagnostic examination on a warm-blooded animal using a .sup.195m Au-containing liquid.

Abstract: A modified liquid-liquid extraction system is disclosed in which a particulate solid and a liquid, both insoluble in a second liquid, are mixed to form agglomerate particles which efficiently extract metal ions from dilute solutions. The extraction is rapid and requires a much lower volume of extracting phase for good contacting than conventional liquid-liquid extraction. Mixing energy is low, clean-up of effluent water is easily accomplished and metal values are readily stripped from the agglomerates by well-known techniques, such as treatment by aqueous acid solution.

Abstract: Arsenic is recovered from flue dusts by forming an aqueous slurry of the dust, treating the slurry with SO.sub.2 gas to solubilize arsenic, and precipitating the arsenic as As.sub.2 O.sub.3 by means of sulfuric acid.

Abstract: The invention relates to a process for separating seminoble and/or noble metals from an aqueous solution having compounds of these metals dissolved therein by subjecting the solution to reaction with red phosphorus. More particularly, the solution is conveyed through a zone containing a layer of granular red phosphorus particles with a size of 0.01 to 10 mm, which may be used in admixture with active carbon.

Abstract: A process for selective liquid-liquid extraction of germanium from an aqueous acidic liquor containing, besides germanium, at least another metal selected from the group which comprises cadmium, zinc, cobalt and nickel. This process includes extracting germanium from said aqueous liquor by contacting said liquor with an organic medium containing a diluent and an extractant, said diluent being immiscible with said aqueous liquor. The major part of germanium passes from said aqueous liquor to an organic phase which is subsequently submitted to a stripping step by contacting with an alkaline medium, with formation of an aqueous phase containing the major part of germanium from said aqueous liquor.

Abstract: Novel sequestering agents useful for the extraction of metal values and in various organic syntheses comprise a cross-linked organic polymeric substrate, said substrate having covalently coupled thereto a plurality of functional groups, the free valence of which having the structural formula: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.6 and R.sub.7, which are identical or different, each represents a hydrogen atom or an alkyl radical having 1 to 4 carbon atoms, R.sub.5 and R.sub.8, which are also identical or different, each represents a hydrogen atom, an alkyl or cycloalkyl radical having 1 to 12 carbon atoms, a phenyl radical, a --C.sub.g H.sub.2q --.phi. or C.sub.q H.sub.2+1 --.phi.-- radical, and further wherein q ranges from 1 to about 12, and n, m and p, which are also identical or different, range from 1 to 10, and .phi. is phenyl.

Abstract: This disclosure concerns primarily the recovery of hydrogen-reduced metals from aqueous solutions of salts thereof, by hydrogen reduction at a porous hydrophobic catalytic barrier, at ordinary temperatures, in an apparatus provided with means to supply hydrogen to one face and aqueous solution to the other face of said barrier.

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 process for the production of a sulphidic copper concentrate from a complex sulphidic concentrate containing as its main constituents copper, iron and at least one non-ferrous metal selected from the group consisting of zinc, lead, nickel and cobalt, comprising mixing the complex sulphidic concentrate with a copper-containing predominantly chloridic solution thereby to form a suspension, and treating the suspension thus obtained at elevated temperature and pressure at a pH-value of below 3, thereby to form a sulphidic copper concentrate, thereby the non-ferrous metals being extracted from the concentrate without formation of significant amount of acid. Precious metals may also be present. Advantageously the ratio by weight of the complex concentrate added to the copper-containing predominantly chloridic solution to the copper content of the solution is such that the predominantly chloridic solution after being at least partly freed from copper by an exchange reaction has a potential at 60.degree. C.

Abstract: To a coal-fired furnace that uses electrostatic precipitation or a mechanical collector to collect fly ash, a mix of magnesia-alumina or magnesia-talc is added above the fireball (2600.degree.-3300.degree. F.). The additive increases the mean particle size of the fly ash and reduces its surface resistivity, thereby causing improved collection in the electrostatic precipitators or mechanical collector. Fine particulates containing heavy metals tend to be agglomerated; thus the invention permits recovery of substantial amounts of heavy metal contaminants that would otherwise be lost as stack emission.