Abstract: Provided is a method for producing calcium zincate. The method comprises: an extraction step: mixing a ground zinc-containing raw material with an extracting agent, followed by filtration to obtain an extract, wherein the extracting agent is a mixed aqueous solution of ammonia and {NH4HCO3 and/or (NH4)2CO3; optionally, purifying the extract; a decarburization step: adding calcium oxide and/or calcium hydroxide to the extract, stirring, and filtering to obtain a first solid and a first filtrate; a calcium zincate synthesis step: adding calcium hydroxide and/or calcium oxide to the first filtrate, stirring to react, and filtering to obtain a second solid and a second filtrate; optionally, rinsing the second solid with water; a drying step: drying the second solid to obtain the final calcium zincate product.

Abstract: A method of reclaiming cadmium material from photovoltaic (PV) modules is provided. The method includes submerging one or more portions of a PV module in a solution including non-distilled water, wherein the one or more portions of the PV module are submerged until cadmium material present on the PV module dissolves into the solution, boiling the solution until the dissolved cadmium material precipitates, and collecting the precipitated cadmium material.

Abstract: A method for removing soluble ferrous iron from a galvanizing flux solution includes circulating the flux solution through a concentration loop and injecting ozone into the concentration loop, wherein the ozone mixes with the flux solution and reacts with soluble ferrous iron to form insoluble ferric iron in the loop. Flux solution that is substantially free of insoluble ferric iron may be removed from the concentration loop through a filter medium such as a cross-flow microfilter, thereby concentrating the ferric iron in the concentration loop. The ozone may be injected through an eductor that utilizes motive force from a circulation pump, thereby reducing energy consumption and providing rapid mixing and reaction of ozone and ferrous iron.

Abstract: A method of precipitating a zinc containing solid from an acidic solution containing dissolved zinc and magnesium comprising contacting the solution with a calcium containing neutralizing agent to raise the pH of the solution to 4.5 to 7.5 at a temperature of from 70 to 95° C. to thereby precipitate a solid zinc containing material and gypsum without causing substantial precipitation of magnesium, and separating the zinc containing material from the gypsum.

Abstract: Zinc and lead are usually concomitantly present in Zn—Pb ores and tailings. A novel non-polluting hydrometallurgical process for selectively leaching and recovering zinc (Zn) from a composite lead (Pb) and zinc sulphide containing mineral, crushed untreated rock or unconsolidated mineral particles, mill tailings and/or agglomerated or unagglomerated sulphidic zinc containing waste material without necessitating smelting and refining operation has been developed. A combination of selected oxidant and alkali metal hydroxide has been found effective. A leachant consisting of e.g. a mixture of sodium hydroxide (NaOH) and sodium hypochlorite (NaOCl) is employed to selectively dissolve zinc sulphide at high pH at standard temperature and pressure (STP). The kinetics of leaching along with the effect of varying concentration (preferably of sodium hydroxide and sodium hypochlorite) were systematically investigated. Feed ore containing diverse set of minerals e.g.

Abstract: There is provided a process for decontaminating and converting volumetrically contaminated radioactive metals, especially nickel, and recovering a decontaminated metal hydroxide or metal carbonate. The process includes the use of hydrogen peroxide to oxidize and remove nucleotides.

Abstract: A method of precipitating a zinc containing solid from an acidic solution containing dissolved zinc and magnesium comprising contacting the solution with a calcium containing neutralising agent to raise the pH of the solution to 4.5 to 7.5 at a temperature of from 70 to 95° C. to thereby precipitate a solid zinc containing material and gypsum without causing substantial precipitation of magnesium, and separating the zinc containing material from the gypsum.

Abstract: Zinc and lead are usually concomitantly present in Zn—Pb ores and tailings. A novel non-polluting hydrometallurgical process for selectively leaching and recovering zinc (Zn) from a composite lead (Pb) and zinc sulphide containing mineral, crushed untreated rock or unconsolidated mineral particles, mill tailings and/or agglomerated or unagglomerated sulphidic zinc containing waste material without necessitating smelting and refining operation has been developed. A combination of selected oxidant and alkali metal hydroxide has been found effective. A leachant consisting of e.g. a mixture of sodium hydroxide (NaOH) and sodium hypochlorite (NaOCl) is employed to selectively dissolve zinc sulphide at high pH at standard temperature and pressure (STP). The kinetics of leaching along with the effect of varying concentration (preferably of sodium hydroxide and sodium hypochlorite) were systematically investigated. Feed ore containing diverse set of minerals e.g.

Abstract: In some embodiments, the invention provides systems and methods for removing carbon dioxide and/or additional components of waste gas streams, comprising contacting the waste gas stream with an aqueous solution, removing carbon dioxide and/or additional components from the waste gas stream, and containing the carbon dioxide and/or additional components, in one form or another, in a composition. In some embodiments, the composition is a precipitation material comprising carbonates, bicarbonates, or carbonates and bicarbonates. In some embodiments, the composition further comprises carbonate and/or bicarbonate co-products resulting from co-processing SOx, NOx, particulate matter, and/or certain metals. Additional waste streams such as liquid, solid, or multiphasic waste streams may be processed as well.

Abstract: A method of preparing basic metal carbonate selected from the group consisting of zinc carbonate, nickel carbonate, silver carbonate, cobalt carbonate, tin carbonate, lead carbonate, manganese carbonate, lithium carbonate, sodium carbonate, and potassium carbonate from metals comprising: contacting the metal with an aqueous solution comprising an amine, carbonic acid, and oxygen under conditions where the metal is converted into basic metal carbonate; and recovering the basic metal carbonate.

Abstract: Method for producing hydrometallurgical zinc oxide powder having characteristics equivalent to that derived from a French process, comprising formation of an aqueous pulp from a starting zinc oxide having particles of nodular structure, wet milling of this aqueous pulp, separation in this milled pulp between a liquid phase and a solid phase containing the zinc oxide, and drying of said solid phase, coupled with a mechanical deagglomeration of the particles during drying, to obtain a dry zinc oxide powder with particles of nodular structure having a particle size distribution where the particles have an average size (d50) between 0.02 and 20 ?m.

Abstract: A method for extraction of zinc values from an aqueous alkaline solution of zinc, especially a solution obtained by the stripping of a galvanized coating from a ferrous metal product e.g. steel, or from electric arc furnace dust. The method comprises subjecting the aqueous alkaline solution to solvent extraction using an organic solution of an oxine i.e. an organic extractant containing an 8-hydroxyquinoline group, and separating the organic solution from aqueous alkaline solution. Zinc values are recovered from the organic solution e.g. by stripping with acid and subjecting the resultant aqueous solution containing zinc values for recovery of zinc e.g. to electrowinning or to precipitation of zinc carbonate. The method may be used in the preparation of galvanized steel for recycle to a steel manufacturing plant, with recovery of zinc and for recovery of zinc values from electric arc furnace dust.

Abstract: Mesoporous metal carbonate structures are formed by providing a solution containing a non-ionic surfactant and a calcium acetate salt, adding sufficient base to react with the acidic byproducts to be formed by the addition of carbon dioxide, and adding carbon dioxide, thereby forming a mesoporous metal carbonate structure containing the metal from said metal salt.

Abstract: A method for preparing basic zinc carbonate from die casting ash, zinc skimming or zinc ash includes heating urea or a mixture of urea and ammonia and carbon dioxide with water in a closed vessel with zinc ash. After zinc is dissolved in sufficient quantities, the solution is cooled and filtered. The filtered solution is cemented with zinc dust to precipitate heavy metals and the filtered. The solution is preferably heated a second time to remove an iron precipitate. The solution is then heated a third time to precipitate the dissolved zinc as basic zinc carbonate, which is washed and dried. The filtrate and gases recovered from the heating steps are reused in the process.

Abstract: A method for treating residues derived from garbage and/or industrial waste incineration fumes including the steps of desalting the residues by washing with sodium carbonate in sufficient amount or slightly in excess to solubilize all the salts including the sulphates and precipitate the soluble calcium, the pH being higher than 11, then carrying out a solid/liquid separation to obtain a desalinated cake; leaching the desalinated cake with sodium carbonate in sufficient amount or slightly in excess to obtain, by reaction with the lime present in the cake or added thereto if necessary, the alkalinity required for solubilising amphoteric metals, the pH being higher than 12, and obtaining by solid/liquid separation a cake and a supernatant which is neutralised with carbon dioxide, and filtering the recovered solution to obtain metal hydroxide sludge and an aqueous sodium carbonate solution; and neutralising the resulting residues at a pH between 6.5 and 8.5.

Abstract: A process for the recovery of a metal, in particular, cadmium contained in scrap, in a stable form. The process comprises the steps of mixing the cadmium-containing scrap with an ammonium carbonate solution, preferably at least a stoichiometric amount of ammonium carbonate, and/or free ammonia, and an oxidizing agent to form a first mixture so that the cadmium will react with the ammonium carbonate to form a water-soluble ammine complex; evaporating the first mixture so that ammine complex dissociates from the first mixture leaving carbonate ions to react with the cadmium and form a second mixture that includes cadmium carbonate; optionally adding water to the second mixture to form a third mixture; adjusting the pH of the third mixture to the acid range whereby the cadmium carbonate will dissolve; and adding at least a stoichiometric amount of sulfide, preferably in the form of hydrogen sulfide or an aqueous ammonium sulfide solution, to the third mixture to precipitate cadmium sulfide.

Abstract: A process is provided for obtaining high quality high surface area zinc oxide from a roasted zinc sulphide concentrate by leaching with an ammoniacal ammonium carbonate solution. The process utilizes optional preliminary oxidation and water leaching steps to remove soluble impurities and an optional aqueous sulphur dioxide leaching step to selectively remove readily soluble zinc oxide. The process includes an improved source of roasted zinc sulphide concentrate. The process also includes an optional reduced pressure calcining step to produce zinc oxide with further increased surface area.

Abstract: A process is provided for obtaining high quality high surface area zinc oxide from a roasted zinc sulphide concentrate by leaching with an ammoniacal ammonium carbonate solution. The process utilizes optional preliminary oxidation and water leaching steps to remove soluble impurities and an optional aqueous sulphur dioxide leaching step to selectively remove readily soluble zinc oxide. The process also includes an optional reduced pressure calcining step to produce zinc oxide with further increased surface area.

Abstract: A process for the heavy-metal decontamination of contaminated substances such as natural and industrial sludges, thermal residues and soils. The contaminated starting substance is treated with an acid and the dissolved metal salts are precipitated as metal hydroxides in the pH range of about 3.5-11. The exact control of the pH value makes it possible to isolate individual metal fractions which can be used as raw materials in the metallurgical industry.

Abstract: Process for removing Sr and heavy metals from water in particular from waste water by throughly mixing it with a solution of an alkali metal carbonate and/or hydrogen carbonate in a reactor containing a fluidized bed of suitable bed material. The obtained heavy metal carbonate crystals crystallize onto said bed material and the obtained heavy metal carbonate crystals in granular form are removed from the reactor from time to time.The heavy metals which may be removed are Ni, Zn, Cu, Fe, Ag, Pb, Cd or Hg.

Abstract: A process for distillation-crystallization of a zinc carbonate which is characterized in that a distillation column having a plurality of plates or trays is used for crystallizing basic zinc carbonate (2ZnCO.sub.3.3Zn(OH).sub.2 or ZnCO.sub.3.3Zn(OH).sub.2 H.sub.2 O) from a solution of basic zinc ammonium carbonate (Zn(NH.sub.3).sub.4 CO.sub.3); said solution is fed to an upper portion of the distillation column, while heating a bottom portion of the distillation column, to effect a distillation operation.

Abstract: A chemical, electro-chemical process for recovering meta values from a zinc- or lead-containing material comprises:in a solubilization stage, oxidizing the zinc- or lead-containing material by treating said material with a ferric chloride leach solution;when solubilized lead is present, separating it from the pregnant liquor forming an essentially lead free solution;dividing this essentially lead free solution into two portions;passing one portion of the essentially lead free solution into the anolyte compartment of a Zn.degree. producing electrolysis stage for use as the ferrous ion-containing anolyte thereof;separating iron from the second portion of the essentially lead free solution, forming an essentially iron free solution;passing the essentially iron free solution into the catholyte compartment of said Zn.degree. producing electrolysis stage for use as the catholyte thereof;conducting electrolysis in said Zn.degree.

Abstract: A mixture of metal hydroxides is leached with an ammoniacal carbonate solution, to dissolve nickel, copper and zinc. Metal is recovered from the leaching solution. The solid leaching residue is leached with sulphuric acid at a pH of 1.5- 3, to dissolve a further amount of nickel, copper and zinc. The acidic leaching solution is passed to the ammoniacal leaching process.

Abstract: A method for recovering a substantially impurity-free zinc oxide product from steel-making flue dust or a similar material which comprises leaching the flue dust with concentrated ammonia and carbon dioxide to dissolve zinc and unwanted impurities, cementing the leach filtrate with zinc to remove copper, cadmium, and lead impurities, conducting a steam distillation on the cementation filtrate to precipitate basic zinc carbonate, remove the ammonia and carbon dioxide, and iron impurities, and filtering to provide a residue of essentially basic zinc carbonate, sulfur, and chromium. This residue is then washed to remove soluble sulfates, dried, and calcined at high temperatures to break down the basic zinc carbonate into zinc oxide, water washed to remove chromium and the residue of the water wash dried to produce the desired impurity-free zinc oxide product. The two water washes may be combined into one step performed after the calcining step to remove both sulfur and chromium in one wash step.

Abstract: The zinc-containing dust from an iron-making (blast) furnace or a steel-refining (e.g. converter) furnace is recovered and extracted with water saturated with carbon dioxide to solubilize the zinc. The zinc solubilized in the CO.sub.2 -saturated water is then precipitated by the elimination of carbon dioxide therefrom.

Abstract: A method for the selective recovery of cadmium, nickel and cobalt from a nickel-cadmium battery waste which comprises:A. leaching the waste with an ammoniacal carbonate solution to form an aqueous ammoniacal carbonate solution containing cadmium, nickel and cobalt (II) ammine complexes and a leaching residue. Any iron in the waste is in the leaching residue.B. adding air to the aqueous ammoniacal carbonate solution to oxidize the cobalt (II) ammine complex to cobalt (III) ammine complex.C. contacting the resulting aqueous ammoniacal carbonate solution with a substantially water insoluble organic solution which contains a hydroxyoxime which forms a nickel compound readily soluble in the organic solution with any nickel present but which does not affect cadmium and cobalt (III). Nickel is thereby removed.D. precipitating the cadmium as a carbonate by removing ammonia from the aqueous ammoniacal carbonate solution and then removing the cadmium in the form of a carbonate.E.

Abstract: A hydrochloric acid leach solution is subjected to a first cycle of extraction by an organic solvent, solvent washing and stripping so that the stripping liquor contains iron, zinc, cadmium and gallium while the liquor constituted by the first raffinate at the outlet of the extraction unit mainly contains nickel, cobalt and copper. In a second extraction cycle, the stripping liquor contains copper while the second raffinate mainly contains cobalt and nickel. In a third extraction cycle, the stripping liquor contains cobalt while the third raffinate mainly contains nickel.

Abstract: A pollution-free process for the recovery of high purity zinc from zinc containing material including sulfide ores which provides for maximum conservation and re-use of reagents, the process consisting of chlorinating the materials either with ferric chloride or chlorine gas followed by selective removal of metals other than zinc by standard procedures, such as, lead chloride crystallization, cementation, etc. to produce a solution containing essentially only zinc chloride and ferrous chloride. To enhance the purity of the zinc end product zinc chloride is separated from the ferrous chloride solution with a zinc selective extraction agent from which the zinc chloride is stripped with sodium chloride solution in a sodium chloride stripping circuit followed by precipitation of zinc as the carbonate.

Abstract: An improved process for preparing highly concentrated salt solutions of metals of high purity from waste metal sludges at superior dissolution rates is achieved by preparing, concentrating and washing the sludge containing insoluble metal hydroxide under specific conditions to safeguard against the solids being exposed to air or dried out. The wet sludge is then dissolved in a dilute acid. The resultant solution can be used directly e.g. as make up in many electrolytic metal finishing processes to compensate for drag out losses occurred, or as the primary metal source in electrolytic processes employing insoluble anodes. Other specific uses for the process include the preparation of aluminum sulfate coagulants.