Abstract: The present invention provides both reagents and a process for removing heavy metals from a caustic fluid stream by the addition of reagents which are not corrosive or deleterious. Specifically, the present invention is directed to removing heavy metals from a Bayer liquor in an aluminum processing plant. The reagents, dithiocarbamate and dithocarbonate groups, are added individually or in combination thereof to the Bayer liquor for the removal of heavy metals, such as zinc. The reagents form a complex with the heavy metal for the precipitation of the metal from the fluid stream. Once a complex is formed, the Bayer liquor is held in a quiescent state for a period of time sufficient for settling out of solution the precipitate. After settling out of solution, the precipitate is separated and removed and the Bayer liquor is then further processed into alumina.

Abstract: A method for the total precipitation of valuable metals, such as copper, nickel, zinc, cobalt, etc., from a leaching solution that has been acidified with sulphuric acid and that is substantially free from impurities, by neutralizing the solution with lime and/or limestone. Neutralization is effected in at least two stages, wherewith only partial precipitation is effected in the first stage, and wherewith full precipitation of remaining valuable metal content is effected in the last stage, by adding a surplus of neutralization agent. Slurry containing precipitates and remaining solid neutralization agent formed in the last stage in the neutralization process is returned to the first neutralization stage, possibly after re-dissolving the slurry in the incoming acid leaching solution. The amount of slurry returned together with any further neutralizing agent added promotes the partial precipitation of the valuable metal content.

Abstract: A process for refining noble metals from auriferous mines, wherein the auriferous material is first milled and treated with a cyanide solution, and comprising: a step for the pretreatment of the auriferous material, wherein the complexes of cyanide with noble metals are fixed on anionic resins and then incinerated; a predefining step, which comprises an etching of the materials incinerated during the pretreatment with a hydrochloric-nitric solution; and specific steps for refining the gold, palladium, platinum and silver.

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

Abstract: The present invention allows one to use a phase I reactor to make thinner silver halide grains. This is accomplished by introducing the halide salt solution and the silver salt solution as close as possible to each other above the mixer head. The reactor is essentially divided into a micro reaction zone and a bulk reaction zone, thus, emulating the effect of a phase II or two stage reactor.

Abstract: Process and apparatus for treating an aqueous effluent with high concentrations of silver and ferric/ferrous complexes using multiple additions of one or more water-soluble sulfur containing polymer chelating agents, with optional additions of non-polymeric sulfur containing compounds. The presence of a high concentration of both dissolved silver and ferric/ferrous complexes prevents efficient silver removal by precipitation and the achievement of a very low residual silver concentration. By using multiple additions of the chelating agent(s), a higher degree of silver removal can be achieved than would be possible with the same amount of chelating agents added in a single stage. Effluent from photo finishing operations, particularly minilabs, can be effectively treated so that there is essentially no silver remaining in the treated effluent.

Abstract: The production of a silver halide emulsion in an aqueous protective colloid solution by the reaction of, on the one hand, silver nitrate, and, on the other, at least one water-soluble halide, may be performed particularly simply and with great apportioning accuracy, if, during at least part of the precipitation, at least the predominant part of one reactant is added in the form of a solid salt to the aqueous protective colloid solution.

Abstract: A dimethylamine silver bromide complex is used as a single source precursor for nucleation of silver bromide crystals.

Abstract: A dimethylamine silver chloro-iodide complex is used as a single source precursor for iodide incorporation in silver chloride crystals.

Abstract: A dimeitylarnine silver bromo-iodide complex is used as a single source precursor for iodide incorporation in silver bromide crystals.

Abstract: A dimethylamine silver chloride complex is used as a single source precursor for nucleation of silver chloride crystals.

Abstract: The quaternary Zintl material (Et.sub.4 N).sub.4 ?Au(Ag.sub.1-x Au.sub.x).sub.2 Sn.sub.2 Te.sub.9 ! that contains 1-D semiconducting chains composed of four metallic elements is prepared by treating ethylenediamine extracts of a pentanary K--Au--Ag--Sn--Te alloy with Et.sub.4 NI.

Abstract: Thermodynamically-unstable complexing agents which are diphosphonic acids and diphosphonic acid derivatives (or sulphur containing analogs), like carboxyhydroxymethanediphosphonic acid and vinylidene-1,1-diphosphonic acid, are capable of complexing with metal ions, and especially metal ions in the II, III, IV, V and VI oxidation states, to form stable, water-soluble metal ion complexes in moderately alkaline to highly-acidic media. However, the complexing agents can be decomposed, under mild conditions, into non-organic compounds which, for many purposes are environmentally-nondamaging compounds thereby degrading the complex and releasing the metal ion for disposal or recovery. Uses for such complexing agents as well as methods for their manufacture are also described.

Abstract: Solid divalent silver oxide is reacted in hot aqueous alkaline reaction medium with a solid bismuth component and a reducing agent. The reaction product comprises a novel compound containing silver, bismuth, and oxygen, which is used in making cathode pellets for use in alkaline electrochemical cells. The cells exhibit low internal impedance and substantially single voltage discharge characteristic of monovalent silver oxide while retaining a significant portion of the coulombic capacity a of divalent silver cathode, without toxicity problems attendant cathodes containing lead and/or cadmium.

Abstract: A method for oxidizing treatment of molten matte and at the same time directly smelting sulphidic concentrate in a refractory-lined liquid bath reactor, e.g. a converter, into which oxidizing air is introduced below the surface of the liquid bath. For additional supply of energy in order to achieve thermal balance or increase of capacity, sulphidic concentrate is introduced into the gas phase of the liquid bath reactor together with oxygen gas or oxygen-enriched gas by means of a concentrate burner.

Abstract: In a process of producing copper(I) oxide by the action of an aqueous solution of a mineral acid and of oxygen-containing gas on small-lump copper metal with continuous agitation, a temperature from 10.degree. to 40.degree. C., preferably from 15.degree. to 35.degree. C., is maintained to effect a formation of particulate yellow copper(I) oxide (Cu.sub.2 O). An organic acid of the group consisting of formic acid, acetic acid, ascorbic acid, preferably ascorbic acid, may be used in addition to the mineral acid.

Abstract: Thermodynamically-unstable complexing agents which are diphosphonic acids and diphosphonic acid derivatives (or sulphur containing analogs), like carboxyhydroxymethanediphosphonic acid and vinylidene-1,1-diphosphonic acid, are capable of complexing with metal ions, and especially metal ions in the II, III, IV, V and VI oxidation states, to form stable, water-soluble metal ion complexes in moderately alkaline to highly-acidic media. However, the complexing agents can be decomposed, under mild conditions, into non-organic compounds which, for many purposes are environmentally-nondamaging compounds thereby degrading the complex and releasing the metal ion for disposal or recovery. Uses for such complexing agents as well as methods for their manufacture are also described.

Abstract: The present invention is a process for oxidation of a liquid which contains cyanide and soluble metal ions, using an oxygen-containing gas. Art example of such a liquid is the liquid waste produced during metal treatment processes. The disclosed process not only eliminates the cyanide completely, but also converts the metal dissolved in the liquid into granular metal oxides which can be readily recovered.

Abstract: There is disclosed a method of treating a solution, e.g., an alkaline or acidic solution, containing heavy metals ions therein. With respect to alkaline solutions, the method includes providing a body of the solution; contacting the body with a material such as carbon dioxide to change the pH, e.g., to lower the pH to a pH in the range of 9 to 10.5; then treating the solution to further change the pH and cause precipitation of hydroxides, including chromium hydroxide; and separating the hydroxide precipitates from the solution to provide a substantially neutral solution having a reduced amount of chromium ions, for example, contained therein.

Abstract: Silver is recovered from a mixture of seasoned photoprocessing solutions by contacting the solutions with a mercapto-s-triazine or water-soluble salt thereof, the mercapto-s-triazine having the formula ##STR1## wherein: R is hydrogen, --NH.sub.4, --OH, alkyl having 1 to 8 carbon atoms, alkoxy having 1 to 8 carbon atoms, phenyl, cyclohexyl, oxazinyl, phenoxy, --NR'.sub.2 or SR";whereinR' is hydrogen, alkyl having 1 to 8 carbon atoms, phenyl, cyclohexyl, naphthyl or benzyl;and whereinR" is alkyl having 1 to 8 carbon atoms, phenyl, cyclohexyl, naphthyl or benzyl;m is an integer from 1 to 3; andn is 0 or an integer from 1 to 2.Using these compounds, silver ion complexes with the compound of formula I and the complex can be allowed to settle and separated from the solutions to decrease silver ion concentration in the solutions. The mixture of solutions includes a seasoned stabilizer solution and other seasoned solutions, including bleach, bleach-fix, and developer.

Abstract: A method and an apparatus for controlling reactant ion concentration within a precipitation vessel to optimize the reactions occurring therein is disclosed. In one important implementation, the reactant controlled comprises halide ion in a reactor during the precipitation and growth of silver halide grains. In this embodiment, the method includes measuring the amount of halide ion within the precipitation vessel; measuring the flow rates of the halide feed stream and the silver feed stream; storing the measured halide ion concentration and measured feed stream flow rates; computing an estimated smoothed halide ion concentration value as a function of the stored measured halide ion concentration and measured feed stream flow rates; and adjustably controlling the amount of halide ion added to the precipitation vessel as a function of this estimated halide ion concentration value.

Abstract: Geothermal brine is passed through a zone containing a packing metal so as to reduce its tendency to deposit iron/silica scale, reduce corrosivity of the brine, and/or remove and recover metals from the brine. The method polishes the geothermal brine by contacting the brine with a packing metal higher in the electromotive series than silver for a time sufficient for a precious metals to precipitate onto the packing at brine temperature and pH conditions which inhibit iron-rich silica scale. Most preferably, the contacting is accomplished near an injection well at the end of a heat extraction process and the packing comprises coiled zinc-galvanized steel chicken wire mesh packed in a sufficient density to also act as a filter for suspended particles. Alternatively, contacting is also accomplished near the production well. Dissolving the packing in a suitable acid leaves a precious metal-rich residue behind for subsequent recovery.

Abstract: Methods are disclosed for treating smelter flue dust and other smelter by-products so as to recover non-ferrous metals therefrom and convert arsenic and sulfur in the flue dust into non-leachable compounds. The methods allow the flue dust and other smelter by-products such as smelter sludges to be disposed of in a natural environment without subsequent leaching of heavy metals, sulfur, and arsenic. The smelter by-products are mixed with hydrated lie, formed into agglomerates, and roasted at an optimal temperature of about 650.degree. C. to form oxidized arsenic and sulfur which react with the lime in the agglomerates to form non-leachable compounds. The roasted agglomerates are contacted with a basic lixiviant comprising dissolved ammonia and an ammonium salt to dissolve non-ferrous metals such as copper from the roasted agglomerates. Used lixiviant can be boiled to precipitate the non-ferrous metals dissolved therein and vaporize the ammonia, thereby regenerating the lixiviant.

Abstract: Improved methods of heap leaching of copper ore with aqueous sulfuric acid solutions comprising a fluoroaliphatic surfactant are disclosed. The fluoroaliphatic surfactant increases the amount of copper values leached and recovered.

Abstract: Geothermal brine is passed through a zone containing a packing metal so as to reduce its tendency to deposit iron/silica scale, reduce corrosivity of the brine, and/or remove and recover metals from the brine. The method polished the geothermal brine by contacting the brine with a packing metal higher in the electromotive series than silver for a time sufficient for a precious metals to precipitate onto the packing at brine temperature and pH conditions which inhibit iron-rich silica scale. Most preferably, the contacting is accomplished near an injection well at the end of a heat extraction process and the packing comprises coiled zinc-galvanized steel chicken wire mesh packed in a sufficient density to also act as a filter for suspended particles. Alternatively, contacting is also accomplished near the production well. Dissolving the packing in a suitable acid leaves a precious metal-rich residue behind for subsequent recovery.

Abstract: The invention provides a method of forming copper arsenate. Copper and arsenic are leached into a treatment solution maintained at a pH level of about 2 to 5 in the presence of at least one impurity. An oxidant is added to the treatment solution to oxidize the copper and arsenic. A copper arsenate compound is precipitated from the solution as copper arsenate. Preferably, the copper arsenate is then releached in a purification solution. The molar ratio of copper to arsenic is adjusted to a level of at least 2. The pH of the purification solution is then increased to precipitate copper arsenate having a decreased concentration of said at least one impurity. Impure copper arsenate may be suspended and reacted in a recrystallization solution preferably having cupric ion. The pH of recrystallization solution is adjusted to a valve between about 1 and 4.5.

Abstract: A method and apparatus for manufacturing silver halide grains wherein a water-soluble silver salt solution and a water-soluble halide solution are separately introduced within a hollow cylindrical structure open at each end which is rotatable mounted about its longitudinal axis within a reaction vessel containing a colloidal aqueous solution. The colloidal aqueous solution within the cylindrical structure is stirred and mixed during the addition of the silver salt solution and halide solution and the silver halide grains which form within the cylindrical structure are immediately discharged into the colloidal aqueous solution between the outer circumference of the cylindrical structure and the reaction vessel through slits in the circumference of the cylindrical structure.

Abstract: Copper arsenate, substantially free from impurities that form sludge in wood preservatives such as chromated copper arsenate, is prepared by adding a solution of soluble arsenate to copper sulfate solution, either or both solutions containing sludge-forming impurities, to form a copper and arsenic-containing solution without precipitating copper arsenate. The pH during the adding is controlled at a value in the range of 1.8 to 2.2 to precipitate impurities. Precipitated impurities are removed, and the copper and arsenic-containing solution is neutralized with a suitable alkaline substance to pH 3.5 to 5.0 to precipitate copper arsenate. Arsenate solution is derived from arsenic oxides, soluble arsenic salts and compounds and metallurgical materials capable of yielding water-soluble arsenate. Copper sulfate solution is derived from crystals and compounds and metallurgical materials cable of yielding copper sulfate.

Abstract: The present invention relates to a method for the selective extraction of the metals gold, silver, platinum or mercury ions or colloidal gold, from an aqueous solution containing at least one of these metal ions which comprises contacting the solution, at a pH of 2 or less, with cells or cell extracts of a microorganism capable of binding these metals for a period of time and under conditions sufficient to allow binding of the metals to the cells or cell extracts.

Abstract: A method for removing iron(III), copper(II), zinc(I) and nickel(II) from an effluent containing chelant (EDTA, DEPA, HOEDTA) comprising treating the effluent with a soluble calcium compound (e.g., Ca(OH).sub.2) CaCl.sub.2, Ca(NO.sub.3).sub.2) in a molar equivalent to the chelant in combination with a monovalent hydroxide to a pH greater than 12.4 and then adding an effective amount of a dialkyldithiocarbamate (e.g.; sodium-N,N-diethyldithiocarbamate) to precipitate the metal hydroxides and nickel dialkyldithiocarbamate. Heating the solution to about 180 F. further speeds up the removal of the nickel(II). The nickel concentration of spent chelant cleaning solution can be reduced to less than 1 ppm.

Abstract: Copper arsenate, substantially free from impurities that will form a sludge in the process for producing wood preservatives such as chromated copper aresenate and having a water content of less than 15%, is prepared by mixing a solution of soluble arsenate and a copper sulfate solution, either or both solutions containing sludge-forming impurities, to form a copper and arsenic-containing solution without precipitating copper arsenate. The pH during the adding is controlled at a value in the range of 1.7 to 2.2 to precipitate impurities. Precipitated impurities are removed, and the copper and arsenic-containing solution is neutralized with a suitable alkaline substance, preferably dilute sodium hydroxide solution, to pH 3.2 to 4.2 to precipitate copper arsenate.

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

Abstract: Refining of either niobium hydroxide or tantalum hydroxide containing transition metals as impurities is accomplished easily and economically by dissolving the metal hydroxide in an aqueous solution of either hydrofluoric acid or oxalic acid, adjusting the pH of the solution to 1 to 4 and adding ammonium pyrrolidinedithiocarbamate (APDC) to the solution while maintaining the temperature of the solution below 60.degree. C. The addition of APDC causes the transition metals to simultaneously precipitate as coordination compounds. The minimum amount of APDC is 0.05 wt % of Nb.sub.2 O.sub.5 or Ta.sub.2 O.sub.5 that can be formed from Nb or Ta contained in the solution. After the treatment with APDC the pH of the solution is raised to 6 or above to precipitate the refined metal hydroxide.

Abstract: The present invention involves the isolation or leaching of noble metals from materials containing noble metals, e.g. ores, by treating the noble metal- containing materials with a cyclic thiourea derivative under acid pH conditions. Removal is effected by adsorption onto charcoal or by an ion exchanger, for example. Preferred cyclic thioureas are N,N'-ethylenethiourea and N,N'-propylenethiourea and the acid pH conditions may be achieved by sulfuric acid or hydrochloric acid solutions containing 0.01 to 2.0% by weight of the cyclic thiourea.

Abstract: This invention is directed to an improved process for leach treating gold and silver bearing pyritic and arsenopyritic concentrates and ores. More particularly, the improved process avoids the necessity of adding recycled neutralized solution to the leach solution, thereby alleviating difficulties in maintaining acid levels in the leach solution, and provides for bleeding solutions containing dissolved arsenic, iron and sulphate from the process without the loss oxidized nitrogen species. The process can be carried out in one or more tubular reactors. The process for recovering valuable metals from pyritic and arsenopyritic concentrates and ores involves decomposing the arsenopyrite or pyrite concentrates and ores in acidic solution in a common volume space which contains a gas phase and a liquid slurry (which comprises a liquid phase and a solid phase) through the action of higher valence oxidized nitrogen species in which the nitrogen has a valence of at least plus 3.

Abstract: Improvement to the separation and recovery of solids from liqiuds containing them, and using a ionic flotation process, implementing an installation characterized in that it comprises at least a vat (1) for pretreating the solution to be treated for the insolubilization of the solid to be recovered and the formation of a suspension maintained under stirring conditions (stirrer 2), at least a flotation cell (5) supplied with said suspension, at least a device (4) provided between said vat (1) and said flotation cell (5) adapted to generate within the cell a rising non-turbulent stream intended to convey the desired solid towards the surface of said suspension while maintaining at said surface a calm area for the accumulation of said solid and at least one means for the recovery of said solid (6-7).

Abstract: Methods of and apparatus for recovering silver and other metals from solutions containing compounds of those metals. The solution being treated is pumped upwardly under pressure and at a constant rate through a reaction mass or medium to promote ion exchange reactions between the metal of interest in the solution and the material making up the reaction mass and thereby precipitate the metal of interest from the solution being treated.

Abstract: Modified starch compositions and their use for flocculating mineral waste residues, particularly the red mud containing alumina liquors from bauxite residues, comprising the addition to an alumina liquor of a flocculating amount of a methylated starch which, optionally, may be hydrolyzed, or a methylated starch which is also sulfonated and, optionally, may be hydrolyzed. Preferably, the methylated starch compositions are potato and dasheen starch derivatives prepared at temperatures of about 50.degree. to about 85.degree. C.

Abstract: A method for obtaining silver and manganese metal from a silver-manganese ore includes the step of leaching the ore with acidified thiourea. More specifically, the method includes the step of leaching the ore with an acidic thiourea solution to form a leach liquor containing compounds of silver and manganese and an insoluble ore residue. The leach liquor is contacted with a quantity of activated carbon to adsorb the silver thiourea complexes on the carbon and to form an extract solution containing the manganese compounds. Next, the carbon which contains adsorbed silver thiourea complexes is contacted with an eluant to desorb the silver complexes from the carbon. The silver metal is recovered from the silver complexes obtained from desorbing the carbon. The manganese metal is recovered from the extract solution. The ore subjected to acidic thiourea leaching is selected from the group consisting of in situ ore, mined ore, comminuted ore, and ore concentrate.

Abstract: A method for producing finely divided stable cupric hydroxide composition of low bulk density comprising contacting solutions of an alkali metal carbonate or bicarbonate and a copper salt, precipitating a basic copper carbonate--basic copper sulfate to a minimum pH in the range of greater than 5 to about 6, contacting the precipitate with an alkali metal hydroxide and converting basic copper sulfate to cupric hydroxide, within the pH range of 7 to 11.

Abstract: A process for the hydrometallurgical recovery of gold and silver by direct oxidizing sulphuric acid-digestion of arsenopyrite-concentrates (FeAsS.sub.2) containing carbonaceous materials with a silicate gangue, and/or a silicate and pyrite gangue whereby arsenic and iron are fully solubilized and the noble metals are quantitatively enriched in the silicate-residue. The concentrate is subjected to mechano-chemical stress to produce structural deformations before being digested in the presence of oxygen. After decarbonization of the residue, gold and silver can be recovered by cyanide leaching without losses due to adsorption. A bulk process for preparing gold and silver rich concentrates is also disclosed.

Abstract: A hydrometallurgical process for enrichment of gold, platinum and palladium from copper electrolysis anode sludge, and simultaneously recovery of selenium, in which the sludge is treated with Cl.sub.2 /HCl to transform the selenium of a hexavelent state and precipitate out silver chloride. The filtrate is then subjected to selective reduction of precipitate the noble metals and the resulting filtrate is chlorinated and a further reduction is effected to precipitate the metallic selenium.

Abstract: A wood preservative contains a water-soluble, alkaline copper(II) complex and a water-soluble thiocyanate or iodide and may contain a reducing agent.

Abstract: A method is disclosed for controlling the deposition of metal-containing scales, such as iron silicate scale, from a hot, aqueous, geothermal brine or the like, without substantial corrosion of brine handling equipment. The brine is contacted with (1) an amount of an acid sufficient to reduce the pH of the brine between 0.1 and 0.5 unit and (2) a greater than stoichiometric amount of a reducing agent for reducing trivalent iron and manganese cations in a high temperature brine solution to divalent ions. An overall decrease in scale deposition, especially of iron silicate scale, is achieved while a silver-rich scale can be recovered from silver-containing brines.

Abstract: Cemented silver powder is thermal conditioned in order to preserve the cemented silver powder morphology through subsequent processing operations.

Abstract: In accordance with the invention, an improved process is provided for the efficient removal and recovery of silver from an impure solution containing silver ions which comprises contacting the silver-containing solution with an activated alumina adsorbent to selectively adsorb the silver ions from the solution and the lower the subsequent effluent discharge to less than 1 ppm silver, treating the activated alumina with a regeneration fluid to recover the silver ions from the adsorbent, and reducing the recovered silver ions to metallic silver.

Abstract: An improved process for recovering gold from gold-containing materials by iodide/iodine leaching is provided wherein the pregnant lixiviant containing solubilized gold and iodine is treated in an electrolytic cell to reduce gold in solution to elemental gold for recovery and reduce iodine to iodide at the cathode, so as to prevent iodine from interfering with subsequent gold recovery processes, and at the same time reoxidize iodide present at the anode to elemental iodine to regenerate the leach solution to the desired iodide:iodine weight ratio, e.g. about 2:1 to about 10:1. Gold is precipitated in the cathode compartment, and if desired, the cathode effluent may be treated for further removal of traces of gold before being passed to the anode compartment. A method for preventing iron contamination of the cathode is also provided comprising buffering the lixiviant solution to a pH of about 5.

Abstract: A process for the recovery of precious metals from ore containing the same is disclosed. The process includes the formation of a lixiviant solution including a thiourea compound, urea and an alkali lignin sulfonate. The ore is then exposed to this lixiviant solution to extract the previous metals therefrom, and the dissolved previous metals are then recovered from the solution.

Abstract: This invention is a process for removing mercury from the desorption or cyanide liquor of a precious metal recovery, cyanide leach system. A sulfide ion-producing compound and a flocculating agent are added to the desorption liquor to form and flocculate mercuric sulfide. The desorption liquor typically has a cyanide concentration of between about 0.5 percent and about 2.0 percent by weight. The flocculated mercuric sulfide is separated from a substantially mercury-free precious metal-containing, cyanide solution.

Abstract: Silver salts, preferably AgClO.sub.4, AgBF.sub.4, and AgPF.sub.6 are oxidized electrolytically at -15.degree. to +10.degree. C. and a pH between 4.5 and 7.5 with a current density of 40 to 200 A/m.sup.2 to produce pure silver (III) oxide.