Abstract: A method for removing heavy metals from wastewater streams removes such heavy metal by treating heavy metal-containing wastewater with a water soluble tri-thio carbonate, particularly an alkali metal tri-thio carbonate, such as sodium tri-thio carbonate (Na.sub.2 CS.sub.3) to precipitate heavy metals therefrom.

Abstract: A process is provided for hydrometallurgical processing of steel plant dusts containing cadmium, lead, zinc, and iron values, along with impurities such as chloride and fluoride salts of sodium, potassium, magnesium, etc. The first step in the process involves leaching the dust in a mixed sulfate-chloride medium that dissolves most of the zinc and cadmium. Any iron and aluminum dissolved in this step is precipitated by oxidation and neutralization. Zinc is recovered from the resulting solution by solvent extraction which provides a raffinate which is recycled to the leaching step with a bleed stream also provided for recovery of cadmium and removal of other impurities from the circuit. The lead sulfate residue from the leaching step is leached with caustic soda, and zinc dust is used to cement the lead out from the caustic solution, which then joins the main solution for zinc recovery.

Abstract: A method of removing complexed zinc-cyanide from wastewater involving a multiple stage process including, in a first step, control of ferrous ions to a critical minimum concentration of 250 to 400 ppm, together with pH control in the first and also a second step, together with recycling of a portion of sludge precipitated in the process. Improved sludge stability is achieved by aeration to oxidize precipitated ferrous hydroxide to ferric hydroxide, immediately before settling the sludge in a thickener.

Abstract: A process for the treatment of a spent hydrochloric acid solution containing dissolved iron, zinc, and minor amounts of heavy metals to remove such dissolved metals from the solution, which process comprises contacting said solution with metallic iron in a first stage, whereby trivalent iron present in the solution is reduced to divalent iron and certain of said heavy metals may be reduced to elemental form, next, in a second stage, contacting said solution with metallic zinc, whereby any remaining heavy metals are reduced to elemental form, and then extracting zinc, as zinc chloride, from the resulting aqueous phase with an organic liquid containing a complexing agent for zinc chloride.

Abstract: There is disclosed a novel method of recovering valuable metals from an industrial by-product containing copper and arsenic and at least one metal selected from among lead, zinc, iron, silver and cadmium, said method comprising leaching the by-product with sulfuric acid in an SO.sub.2 gas atmosphere at a temperature of 70.degree. C. or higher in the presence of a solid sulfide to thereby precipitate copper selectively as copper sulfide while dissolving other metal or metals in the leach solution and then separating the copper containing precipitate from the leach solution, said leach solution containing substantially no copper.

Abstract: There is described a process for the separation and purification of the platinum group metals from base metal out of acidic aqueous solutions. For this purpose there is used a substituted thiourea of the formulaR.sub.1 R.sub.2 N--CS--NH--CO--R.sub.3orR.sub.1 R.sub.2 N--CS--NH--COOR.sub.3as the extraction agent. Preferably there are employed N,N-dialkyl-N'-benzoylthiourea wherein R.sub.1 and R.sub.2 are methyl, n-butyl, or n-hexyl.

Abstract: There is described a process for the separation and purification of the platinum group metals from base metal out of acidic aqueous solutions. For this purpose there is used a substituted thiourea of the formulaR.sub.1 R.sub.2 N--CS--NH--CO--R.sub.3orR.sub.1 R.sub.2 N--CS--NH--COOR.sub.3as the precipitation agent. Preferably there are employed N,N-diaklyl-N'-benzoylthiourea wherein R.sub.1 and R.sub.2 are methyl, n-butyl, or n-hexyl.

Abstract: A process for defluorinating a solution of a sulphate of Zn, Ni, Cd, Mn and/or Mg, in which Al.sup.3+ and PO.sub.4.sup.3- ions are added to the solution, then the solution is neutralized up to a pH higher than 4 and lower than that one that causes a substantial precipitation of Zn, Ni, Cd, Mn and/or Mg, thereby producing a fluorinated precipitate, and the precipitate is separated from the solution.

Abstract: A method for producing and distributing wet zinc dust to a zinc sulfate purification system or other zinc plant operation is disclosed. The method comprises atomizing molten zinc with high pressure water or other suitable medium, and feeding a predetermined amount of the wet zinc dust to at least one zinc sulphate purification tank or any other zinc plant operation.

Abstract: A process is provided for removing hexavalent selenium from an acidic sulfate solution containing at least one metal ion from the group consisting of nickel, cobalt and copper at ambient pressure and at a temperature not exceeding the boiling point of the solution. The solution is treated with an agent from the group consisting of a compound which will produce nascent hydrogen in the solution and finely divided metal from the group consisting of nickel, cobalt and copper resulting from in situ precipitation of the metal in the acid sulfate solution. Thus, following treatment with the compound, the hexavalent selenium is reduced to a form separable from the solution by solid-liquid separation.

Abstract: A method of removing complexed zinc-cyanide from wastewater involving a multiple stage process including, in a first step, control of ferrous ions to a critical minimum concentration of 250 to 400 ppm, together with pH control in the first and also a second step, together with recycling of a portion of sludge precipitated in the process.

Abstract: A process for the selective recovery of cadmium, molybdenum, zinc, nickel and other metal values from wet process phosphoric acid and other acidic to slightly basic carrier solutions, wherein the metal-bearing solution is contacted with an organophosphene extractant to precipitate the metal values for subsequent separation from the solution. Separation may be effected by mechanical means or by scrubbing with a water-immiscible organic solvent such as kerosene for subsequent recovery of the metal values. The metal specie recovered is determined by the concentration of the organophosphene, which may be selectively adjusted to recover a series of metal values in a sequence of stages.

Abstract: A process for purifying an acid aqueous solution containing heavy metals by adding sulfide ions to said acid aqueous solution at a first pH lower than 3.4, precipitating a first heavy metal, adding sulfide ions again to said first precipitate containing acid aqueous solution, after adjusting to a pH of higher than 4, to precipitate a second heavy metal, and then removing the resultant first and second precipitates from the acid aqueous solution.

Abstract: The disclosure relates to a process for liquid/liquid-extraction of heavy metal ions from acid aqueous solutions with the aid of water-insoluble dithiophosphoric acid diesters as extracting agents. More particularly, use is made of phosphoric acid solutions with a P.sub.2 O.sub.5 -content of from 3 to 80 weight %, the solutions being free from emulsion-forming organic contaminants or having previously been freed therefrom in known manner. The resulting aqueous phase is separated from the phase containing the dithiophosphoric acid diester.

Abstract: Anhydrous zinc chloride is produced from an aqueous feed solution containing zinc chloride from an aqueous feed solution containing zinc chloride. The zinc chloride is extracted onto an organic extractant known to the art such as tributyl phosphate, primary, secondary or tertiary amines, and quaternary amine salts. The loaded extractant is then stripped with aqueous stripping solution containing ammonium chloride and ammonium hydroxide. The zinc ammine chloride formed in this aqueous stripping solution is separated from the stripping solution and can then be heated to form anhydrous zinc chloride and ammonia. This anhydrous zinc chloride is suitable as a feed material to a fused salt electrolysis process for the production of zinc.

Abstract: A Bayer process solution is filtered through a bed of particles of a granular substance containing Fe.sub.2 O.sub.3 to remove copper and zinc species from the solution. The particles preferably have an Fe.sub.2 O.sub.3 content of about 40 to 100% by weight. For more effective removal of zinc, the particles are coated with a metal sulfide, preferably zinc sulfide.

Abstract: A pigment for a color-changing heat indicator comprising a product obtained by interaction of an aqueous solution containing ions of copper and mercury with an aqueous solution of a nitrogen-containing organic compound: an amide of carbonic acid, an amide of thiocarbonic acid, a tertiary amine to give a reaction mixture which is reacted with an aqueous solution containing ions of iodine at an atomic ratio of copper:mercury:iodine equal to 2:1.5:3-5 and an amount of the nitrogen-containing organic compound equal to 0.8-8% of the total content of copper and mercury; the pigment has its critical temperature of from 38.degree. to 70.degree. C. and a heat-resistance of from 160.degree. to 180.degree. C.

Abstract: A process for selectively removing ions of copper and/or cadmium from a sulphate solution containing nickel and/or cobalt values. The solution is treated at a temperature in the range of from about 85.degree. to about 95.degree. C. and at a pH in the range of from about 4.5 to about 5.5 with hydrogen sulphide to precipitate copper and/or cadmium ions as copper and/or cadmium sulphide, and the precipitated copper and/or cadmium sulphide is separated from the solution.

Abstract: This invention relates to environmentally sound hydrometallurgical methods and processes for extraction of cobalt, nickel and silver from complex concentrates. The finely ground minerals are converted during an oxidative caustic leach at elevated pressures and temperatures to insoluble metal hydroxides and are separated from soluble sodium arsenate and sodium sulphate. Cobalt and nickel are extracted from the caustic cake during a two-stage sulphuric acid leach. Solution purification for cobalt and nickel recovery proceeds on the basis that only one waste residue and one liquid effluent are generated which meet strict environmental standards. A small amount of cyanidation residue is generated after silver extraction by cyanidation from the acid leach residue. Metal values extraction reaches +99.0%. Arsenic and sulphur can be recovered in an innovative recycle system as sodium, zinc or copper arsenate chemicals and as anhydrous sodium sulphate.

Abstract: Process for the recuperation of an insoluble salt of a metal from the rinsing solution of an electrodeposition of the metal.

Abstract: A process is provided for treating brine sludge to render it suitable for ecologically safe disposal by removing therefrom leachable mercury impurities. The process comprises dewatering the sludge and conveying the dewatered sludge through a series of water washings to remove therefrom leachable mercury to render it suitable for land fill disposal.

Abstract: The present invention relates to a process for removing heavy metals, particularly cadmium, from differing qualities of wet-process phosphoric acids. The invention is based on the concept of removing the heavy metals in sulfide form.

Abstract: A hydrometallurgical process is provided for separative treatment of zinc-bearing metallurgical flue dust containing significant amounts of lead, chlorine, and iron. The process is especially suited for extraction of zinc sulfate from blast furnace white dust resulting in the smelting of secondary copper. According to the process, the flue dust is leached in sulfuric acid solution for substantially complete dissolution of soluble constituents, notably zinc, leaving insoluble residue consisting principally of lead oxide. At completion of leaching, pH is selectively adjusted corresponding to the desired extent of subsequent chloride removal. Second, the loaded leach solution is treated for chloride removal wherein chloride ion concentration is substantially and selectively reduced by precipitation of cuprous chloride, cuprous ions being provided by pH regulated reduction of cupric ions.

Abstract: Method and apparatus for removing heavy metals as sulfides from aqueous liquids. The aqueous liquid is introduced into a circulating liquid loop wherein there are established a mixing zone, a controlled precipitation initiating zone, a crystal growing zone and a crystal settling zone. The aqueous feed liquid containing H.sub.2 S dissolved therein and at a pH below that at which the sulfide is precipitated is mixed in the loop with a pH-adjusting liquid; and the degree of supersaturation with respect to the metal sulfide is maintained within the controlled precipitation initiating and crystal growing zones in the metastable condition so that the growth rate of the metal sulfide crystals remains greater than under uncontrolled conditions vis-a-vis the nucleation rate to effect the production of metal sulfide crystals of a character which makes it possible to separate them through clarification and filtration.

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

Abstract: A rapid, energy efficient, low cost, nonhazardous method for the selective removal of mercury from mercury-containing metal cyanide solutions, particularly the cyanide solutions resulting from the cyanidation of gold ore and the like, wherein a reactive sulfide is admixed with the solution for a time sufficient to form an insoluble mercuric sulfide precipitate. The mercuric sulfide precipitate is then separated from the metal cyanide solution by filtration or other conventional means.

Abstract: Certain sulfonylhydrazines, metal complexes thereof and solutions of said compounds in essentially water-immiscible, liquid hydrocarbon solvents are disclosed. The sulfonylhydrazines have the general structural formula:R--SO.sub.2 NHNH--R.sub.1wherein R and R.sub.1 are as defined in the specification and claims hereof. Particular metal values are recovered from their aqueous solutions by using sulfonylhydrazines dissolved in essentially water-immiscible, liquid hydrocarbon solvents. The extraction process involves contacting the metal value containing aqueous solution with the solution of the sulfonylhydrazines in essentially water-immiscible, liquid hydrocarbon solvent and stripping the metal from the loaded organic phase.

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

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

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

Abstract: This invention relates to stable, fluid zinc-containing dispersions and the preparations thereof by the high temperature decomposition of ZnCO.sub.3 to ZnO in a dispersant-containing fluid.

Abstract: A process for separating lead and zinc from oxidized ore is disclosed. The process is directed to the ammoniacal leaching of the ore in the presence of the anions of polycarboxylic acids, particularly sodium tartrate, and the subsequent selective extraction by means of complex-producing solvents.

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: Cadmium (Cd.sup.++) ions are separated from an effluent containing complexing agent such as nitrilotriacetic acid, ethylenediamine tetraacetic acid and/or diethylenetriamine pentaacetic acid, or their anionic salts by using an HS-containing triazine compound and Fe.sup.+++ ions in a quantity at least equal to the amount of complexing agent.

Abstract: A method is provided for purifying zinc sulphate solutions containing copper, cadmium and cobalt impurities, which comprises, in a first stage, treating the impure zinc sulphate solution with zinc dust and an antimony and/or arsenic compound so as to form a cement containing essentially all the copper and cadmium and a portion of the cobalt and separating this cement from the partially purified solution, then, in a second stage, treating the partially purified solution with zinc dust and an antimony and/or arsenic compound to form a cement containing essentially metallic zinc as well as the remaining cobalt and other incidental impurities and separating this cement from the purified solution and recycling at least the major portion of this cement to the first stage where it is used instead of zinc dust to effect further treatment of a fresh impure zinc sulphate solution. The purified solution from the second stage may also be subjected to a third purification stage for control purposes.

Abstract: A process for the removal of mercury from aqueous media containing mercury and undissolved solids comprises, adding hypochlorite to the aqueous medium, reducing the ionic mercury to elemental mercury, aerating the aqueous medium with a gas to entrain the mercury and separating the mercury from the entraining gas.

Abstract: A process for treating thermally activated metal sulfides containing copper, iron and zinc for separate recovery of zinc as zinc sulfide in which the metal sulfides are subjected to a two-stage countercurrent acid leach for the formation of copper sulfide containing acid leach residue and ferrous sulfate solution. The second-stage acid leach is performed in two steps; the first step is operated at a relatively high pulp density and high acid concentration for iron and zinc extraction, the resulting slurry diluted, and the second step is operated at a relatively low pulp density and low acid concentration for dissolution of precipitated ferrous sulfate and precipitation of any dissolved copper values by H.sub.2 S. The diluent solution for the slurry from the second-stage first step preferably is generated sulfuric acid solution from a jarosite precipitation and iron and zinc-containing solution from a subsequent activation leach.

Abstract: A technique for removing substantially all the elemental mercury from a mercury containing aqueous media by adjusting the pH of the liquid to the range of 7-13, adding a polysulfide in an amount sufficient to combine with the elemental mercury to form a mercury sulfide which is precipitated and preventing the mercury from being resolublized.

Abstract: A process for separating and recovering metal values and salts from brine, such as brine produced from a subterranean geothermal reservoir, in which the brine is pressurized to above the bubble point pressure and thereafter a precipitating agent, such as a soluble sulfide, is added to the brine to form insoluble metal sulfide precipitates. The precipitates are separated from the brine while maintaining the brine at a pressure above the bubble point pressure, and the hot brine is subsequently utilized to derive energy therefrom. The brine effluent after such energy derivation and the precipitate are optionally processed to primarily recover saleable salts and metal values, respectively.

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

Abstract: Zinc is recovered from a material containing zinc and iron. The material is leached with sulphuric acid to produce a final pH of 3-5.5. Zinc powder is added to the leaching solution to precipitate polluting metals. Zinc is now extracted with a solution of a dialkyl phosphoric acid in an organic solvent. Zinc is extracted from the organic solution with sulphuric acid. Zinc is recovered from the sulphuric acid solution as metal or as zinc sulphate.

Abstract: A process for treating a residue from the sulfuric acid leaching of roasted zinc blende, comprising(a) leaching the residue in a single stage with sulfuric acid and a metal sulfide supplied in a quantity sufficient for transforming the iron into divalent iron, the temperature being maintained between about 60.degree. C and the boiling point,(b) heating the mass to a temperature above the melting point of sulfur, separating a first fine-grained residue of low zinc and iron contents and high lead content, and separating a coarse-grained residue containing sulfur, compounds of iron and any excess metal sulfide from (a),(c) adjusting the pH of the residual solution to at most about 2, at a temperature between about 80.degree.

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

Abstract: Mercury and mercury salts are removed from liquid effluents (which may also comprise muds and inert products in suspension) by reacting the liquid effluents, at a pH of from 9 to 14, with thiourea or a hydroxylamine salt, and subsequently separating the resulting precipitate, together with muds and inert products, if any, by clari-flocculation.

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

Abstract: Metal powders, metal oxide powders, and mixtures thereof of controlled particle size are provided by reacting an aqueous solution containing dissolved metal values with excess urea. Upon heating, urea reacts with water from the solution leaving a molten urea solution containing the metal values. The molten urea solution is heated to above about 180.degree. C. whereupon metal values precipitate homogeneously as a powder. The powder is reduced to metal or calcined to form oxide particles. One or more metal oxides in a mixture can be selectively reduced to produce metal particles or a mixture of metal and metal oxide particles.

Abstract: A process for recovery of zinc values contained in thermally activated iron containing copper and zinc sulfides in which said activated sulfides have been subjected to an acid leach in aqueous sulfuric acid to produce a solution of ferrous sulfate and a solids residue containing copper and zinc values. The solids residue containing copper and zinc values is reacted with an acidic copper sulfate solution to precipitate copper values as a simple copper sulfide with concurrent dissolution of iron and zinc values to form a solution of ferrous sulfate containing said dissolved zinc values and said solution of ferrous sulfate is separated from the simple copper sulfides and reacted with H.sub.2 S for precipitation of zinc values therefrom as zinc sulfide. Any nickel and cobalt values present in said activated sulfides is dissolved in said solution of ferrous sulfate and reacted with the H.sub.2 S at elevated temperature for selective precipitaton.

Abstract: The ore is subjected to nitric acid leaching and the leach solution is heated to a temperature at which one of the additional sulfur and iron values is selectively insolubilized with respect to the solution, while the other is maintained in solution for subsequent separation from the liquor after the insolubles have been removed and the liquor has been neutralized. In addition, in one embodiment of the invention the heating and acid neutralization steps are controlled within certain prescribed limits to make it possible to remove the metals from the liquor by solvent extraction without the problem of lasting precipitates forming in the liquor and fouling the extraction process. Where there is a sizable amount of dissolved iron in the liquor, the liquor may be subjected to autoclaving at a temperature above about 149.degree. C (300.degree. F) to precipitate the iron as the oxide thereof. This effect is possible even where the liquor is high in sulfate concentration.

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: CdS for electrophotography is produced by contacting sulfide ion, cadmium ion and a donor impurity of Group IIIa or IIIb of the Periodic Table and firing the resulting CdS. An acceptor impurity may be added to the first step or the second step.