Abstract: The invention provides a process for recovering hydrogen cyanide from an aqueous solution by extracting the hydrogen cyanide into an organic solvent phase. The organic solvent may comprise a neutral organophosphorous compounds, such as compounds selected from the group consisting of alkyl or aryl substituted phosphates, phosphonates and phosphine oxides. In alternative embodiments the organophosphorous compound is tri-butyl phosphate, di-butyl-butyl-phosphonate or tri-alkyl phosphine oxides. The organic solvent may be diluted in an organic diluent, such as an aliphatic or kerosene-type diluent. Alternative dilutions may be used, such as 75%, 50% or 25%. In some embodiments, the pH of the aqueous solution containing dissolved cyanide may be adjusted to between 2 and 8, or between 3 and 7, or between 4 and 6. The organic solvent may be contacted following extraction with a basic aqueous solution to strip cyanide from the organic solvent into a basic aqueous cyanide strip solution.

Abstract: A process is disclosed for the recovery of gold and/or silver values from activated carbon, wherein they are adsorbed as cyanide complexes. The process uses an eluant containing sugar. The process allows the eluant to pass through fresh carbon twice, thereby reducing the volume of the gold-loaded eluant. This, in turn, reduces the size of the electrowinning or zinc precipitation circuits. The process also improves elution efficiency when barren electrowinning solution is recycled in the elution process.

Abstract: An organic-inorganic polymer comprising aluminosilicate having grafted thereon an organic radical having a —SH or —S(—CH2)n—S— group wherein n is from 0 to 4.

Abstract: A process for extracting and recovering copper from an aqueous solution containing copper values comprising: (a) contacting the aqueous copper bearing solution with an organic phase comprising a water insoluble and water immiscible solvent solution of an extraction reagent formulation to extract at least a portion of the copper values into the organic phase; (b) separating the resultant copper pregnant organic phase from the copper baren aqueous phase; and (c) recovering the copper values from the copper pregnant organic phase; wherein the extraction reagent formulation comprise an (i) oxime extractant and (ii) an equilibrium modifier in which the modifier is a linear diester or polyester of an unbranched dicarboxylic acid and an unbranched alcohol.

Abstract: A process for the extraction of metal from an ore or concentrate which contains nickel and/or cobalt values and other metals, comprises subjecting the ore or concentrate to acid leaching under pressure at pH≦2 to obtain a liquor containing nickel and/or cobalt values, subjecting the liquor to a first precipitation stage at pH of about 5 to 6 to produce a solid containing non nickel and non cobalt metals and a resultant solution containing the nickel and/or cobalt values and subjecting the resultant solution to a second precipitation stage at a pH of about 7 to 8 to produce a solid containing nickel and/or cobalt.

Abstract: A method of biotreating a solid material to remove an undesired compound using a nonstirred surface bioreactor is provided. According to the method the surface of a plurality of coarse substrates is coated with a solid material to be biotreated to form a plurality of coated coarse substrates. The coarse substrates have a particle size greater than about 0.3 cm and the solid material to be biotreated has a particle size less than about 250 .mu.m. A nonstirred surface reactor is then formed by stacking the plurality of coated coarse substrates into a heap or placing the plurality of coated coarse substrates into a tank so that the void volume of the reactor is greater than or equal to about 25%. The reactor is inoculated with a microorganism capable of degrading the undesired compound in the solid material, and the solid material is then biotreated in the surface bioreactor until the undesired compound in the solid material is degraded to a desired concentration.

Abstract: A composition for use in extracting copper values from aqueous solutions of metal salts comprises one or more o-hydroxyaryloximes containing at least 5 aliphatic or alicyclic carbon atoms which are strong metal extractants which, in 0.2 molar solution in an aliphatic hydrocarbon solution when loaded with 50% of the theoretical uptake of copper, will be in equilibrium with a 0.1 molar solution of copper as copper perchlorate at a pH less than 1 and one or more branched chain aliphatic or aliphatic-aromatic esters containing 10 to 30 carbon atoms, wherein the ratio of the number of methyl carbon atoms to the number of non-methyl carbon atoms is higher 1:5 and the weight ratio of A to B being in the range of 10:1 to 1:3.

Abstract: Novel modified and improved beta-diketones and their use in the extraction of copper from aqueous ammoniacal solutions containing copper values, resulting from commercial processes, including, but not limited to, leaching of copper containing ores, such as sulfidic ores, or concentrates resulting from flotation of such sulfidic ores. The novel diketones are those highly sterically hindered, which may be represented by the formula I or II: ##STR1## The preferred beta-diketones of Formula [II] are selected from the group consisting of neo-alkyl beta-diketones, such as, 1-phenyl-3-neoalkyl-1,3 propanedione in which the neoalkyl group is selected from neohexyl, neoheptyl, neooctyl, neononyl, or neodecyl.

Abstract: A method of biooxidizing sulfide minerals in a nonstirred bioreactor is provided. According to the disclosed method, a concentrate of sulfide minerals is coated onto a plurality of substrates, such as coarse ore particles, lava rock, gravel or rock containing a small amount of mineral carbonate as a source of CO.sub.2 for the biooxidizing bacteria. After the sulfide minerals are coated or spread onto the plurality of substrates, a heap is formed with the coated substrates or the coated substrates are placed within a tank. The sulfide minerals on the surface of the plurality of coated substrates are then biooxidized to liberate the metal value of interest. Depending on the particular ore deposit being mined, the sulfide mineral concentrates used in the process may comprise sulfide concentrates from precious metal bearing refractory sulfide ores or they may comprise sulfide concentrates from metal sulfide type ores, such as chalcopyrite, pyrite or sphalorite.

Abstract: A method of removing HMO.sub.2.sup.- anions from an aqueous silicate solution comprising contacting the solution with a cationic ion exchange resin, where M is manganese, zinc, copper, nickel, or a mixture thereof. The method is particularly applicable to solutions of sodium silicate or potassium silicate.

Abstract: Improvement in the process of extracting metals, particularly copper, from aqueous ammoniacal solutions with beta-diketone extractants dissolved in a water immiscible hydrocarbon diluent, such as a kerosene, in which the improvement comprises application of a voltage potential across the interface of the aqueous and organic layers of an extraction circuit with an electrostatic coalescer, and maintaining the voltage potential until the layers have been separated, to control entrainment of the aqueous layer into the organic layer, thereby significantly reducing metal production cost and providing improved metal quality by minimizing ammonia entrapment and carry over to the aqueous stripping solution from which the metal is recovered, typically by electrowinning of the aqueous acid strip solution.

Abstract: Methods for decontaminating toxic waste, particularly solid carrier materials, such as soil contaminated with a toxin, or solid mixed wastes are more efficiently decontaminated with solvated electrons by first extracting the toxin from the carrier with a nitrogenous base at elevated temperatures, followed by a temperature reduction before initiating chemical reduction of the toxin with solvated electrons. Pre-extraction of the toxin at elevated temperatures followed by temperature reduction minimizes competing side reactions, improves selectivity of solvated electrons for the toxin and improves the economics of the process with more efficient metal utilization. The process can be performed without separation of the toxin from the extraction vessel holding the solid carrier material. Alternatively, elevated temperatures can be used to perform one or more extractions of toxin with nitrogenous base followed by reduction with solvated electrons by performing the reaction in a separate reactor.

Abstract: The invention relates to a process for working up charged aqueous solutions, more especially etching solutions, which contain ammonia, at least one ammonium salt and metal ions in dissolved form and which accumulate in the treatment of substrates containing valuable metals, more especially copper-containing electronic sub-assemblies by contacting the aqueous solution with an organic water-immiscible extractant in one or more extraction stages to form an organic phase containing valuable metals and an aqueous phase, (b) washing the organic phase with a water-containing liquid in one or more successive washing stages wherein the water-containing liquid has a pH above 6.5 in the first washing stage and after said washing stage contacting the washing water before reuse with an organic extraction solution, and (c) conducting one or more stripping stages to transfer the valuable metals from the organic phase to an aqueous phase.

Abstract: A process for purifying a degraded oxime metal extractant organic phase from a metal extraction circuit wherein a degraded oxime metal extractant organic phase comprised of an oxime metal extractant, and aldehyde or ketone degradates in a water immiscible hydrocarbon solvent is reoximated thereby restoring the oxime extractant organic phase for further extraction in the metal extraction circuit. Optionally the degraded organic phase may be purified by distillation prior to reoximation. The distillation is carried out in a wiped film evaporator at temperatures above 180.degree. C. up to about 250.degree. C. at a pressure from about 0.5 mm Hg or lower up to about 10 mm Hg and the reoximation is carried out with hydroxylamine in the presence of a weak organic carboxylic acid as a phase transfer catalyst and in the presence of an alkali metal or alkaline earth metal hydroxide or carbonate, preferably sodium carbonate.

Abstract: A method of extracting metalloid and metal species from a solid or liquid material by exposing the material to a supercritical fluid solvent containing a chelating agent is described. The chelating agent forms chelates that are soluble in the supercritical fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is a fluorinated .beta.-diketone. In especially preferred embodiments the extraction solvent is supercritical carbon dioxide, and the chelating agent comprises a fluorinated .beta.-diketone and a trialkyl phosphate, or a fluorinated .beta.-diketone and a trialkylphosphine oxide. Although a trialkyl phosphate can extract lanthanides and actinides from acidic solutions, a binary mixture comprising a fluorinated .beta.-diketone and a trialkyl phosphate or a trialkylphosphine oxide tends to enhance the extraction efficiencies for actinides and lanthanides.

Abstract: The process of recovering precious metals from ores containing precious metals, such as gold and silver, from an aqueous ammoniacal thiosulfate leach solution to provide a significant practical and economical process for the recovery of gold or silver is disclosed. After leaching of the ore with an aqueous ammoniacal thiosulfate solution, the leach solution is contacted with a precious metal extraction reagent to extract the precious metal values from the leach solution, after which the precious metal values are stripped from the extraction reagent to form a concentrated solution of the precious metal values from which the precious metals may be recovered by conventional methods such as electrolysis. The extraction reagents are those having guanidyl functionality or a quaternary amine functionality mixed with a weak organic acid such as a phenol.In the process, novel thiosulfate complexes of the precious metals are formed with the quanidyl or the quaternary amine extractants.

Abstract: An improvement in the process of recovery of copper from aqueous ammoniacal solutions containing copper values in which the copper values are extracted from the aqueous ammoniacal solution by an organic phase comprised of a diketone copper extractant dissolved in a water-immiscible organic hydrocarbon solvent, by improving the stripping of the copper from the organic extractant phase, in which the improved stripping results from the incorporation into, or addition to the diketone extractant phase of a catalytic amount of an hydroxy aryl oxime. Also an improved extractant composition is provided comprised of the mixture of a diketone copper extractant and a catalytic amount (preferably about 0.5 to about 5 mole % in relation to the diketone) of an hydroxy aryl oxime, such as nonyl or dodecyl salicylaldoxime.

Abstract: A process for the extraction of precious metals from a copper sulphide ore or concentrate, by treating a leach residue of the ore or concentrate, includes the steps of removing elemental sulphur from the leach residue to obtain a low sulphur residue and subjecting the low sulphur residue to an oxidative leach at elevated temperature and pressure to oxidize sulphur and precious metal compounds present in the low sulphur residue to produce a residue for the extraction of the precious metals therefrom.

Abstract: The present invention is directed to a process for recovering copper from a copper-containing material by pressure oxidation followed by solvent extraction and electrowinning. The copper-containing solution formed by pressure oxidation is diluted before solvent extraction and the raffinate solution from solvent extraction is neutralized to reduce the acid levels in the raffinate solution.

Abstract: A process for extracting and separating silver safely and selectively from a raw material containing slightly soluble silver compounds and recovering silver from the extract in a simple manner without resorting to electrolysis or a special reducing agent, and further recovering high-purity silver, includes mixing the raw material with an organic solvent solution of an organophosphorus compound containing in the molecule sulfur in the form of S.sup.2- ions, thereby extracting silver into an organic phase simultaneously with dissolving the slightly soluble silver compounds, stripping the silver from the organic phase containing the extracted silver with an aqueous solution of alkali sulfite and forming a stripping solution, and reducing the stripping solution to separate silver therefrom.

Abstract: A composition for extracting a transition metal which comprises as an active ingredient a cyclic phenol sulfide represented by the following formula (1): ##STR1## wherein X represents a hydrogen atom, a hydrocarbon group, an acyl group, a carboxyalkyl group, or a carbamoylalkyl group; Y represents a hydrocarbon group; Z represents a sulfide group, a sulfinyl group, or a sulfonyl group; and n is an integer of 4 to 8; and a method for extracting a transition metal using the composition

Abstract: Ores containing copper, zinc, silver in the form of sulfides are treated by a solution of sulfurated sulfite ions and ammonium ions in order to remove most of the metals from the sulfide ores. This treatment renders the resulting gold bearing ores much more amenable to cyanide extraction. Dissolved metals are reclaimed by appropriate techniques, such as electrowinning or liquid-liquid extraction, and the solution of sulfurated sulfites and ammonia is recycled for further lixiviation of fresh ores.

Abstract: A process for the extraction of a metal from an ore or concentrate comprises subjecting the ore or concentrate to pressure oxidation in the presence of oxygen and an acidic solution containing halogen ions and a source of bisulphate or sulphate ions, such as H.sub.2 SO.sub.4. The metals which can be extracted by the process comprises copper, as well as non-cuprous metals, such as zinc, and precious metals, such as gold and silver.

Abstract: A process for the extraction of zinc from a sulphide ore or concentrate containing copper and zinc includes subjecting the concentrate to pressure oxidation in the presence of oxygen and an acidic halide solution to obtain a resulting pressure oxidation slurry and subjecting the slurry to a liquid/solid separation step to produce a liquor containing copper and zinc in solution. The liquor containing the copper and zinc is subjected to a first solvent extraction with a copper extractant to remove copper from the solution and to produce a copper depleted raffinate. The copper depleted raffinate is subjected to a second solid extraction with a zinc extractant to produce a zinc depleted raffinate and the zinc depleted raffinate is recycled to the pressure oxidation step.

Abstract: This invention relates to a process for making a shaped copper article directly from a copper-bearing material, comprising: (A) contacting said copper-bearing material with an effective amount of at least one aqueous leaching solution to dissolve copper ions into said leaching solution and form a copper-rich aqueous leaching solution; (B) contacting said copper-rich aqueous leaching solution with an effective amount of at least one water-insoluble extractant to transfer copper ions from said copper-rich aqueous leaching solution to said extractant to form a copper-rich extractant and a copper-depleted aqueous leaching solution; (C) separating said copper-rich extractant from said copper-depleted aqueous leaching solution; (D) contacting said copper-rich extractant with an effective amount of at least one aqueous stripping solution to transfer copper ions from said extractant to said stripping solution to form a copper-rich stripping solution and a copper-depleted extractant; (E) separating said copper-rich st

Abstract: Proposed is an efficient method for the highly selective recovery of silver value in an aqueous solution containing silver ions in a low concentration, such as depleted photographic fixing solutions, by extracting the silver ions from the aqueous phase with an organic solution containing 0,0-bis(2-ethylhexyl) hydrogen thiophosphate as an extractant solution and the silver ions contained in the extract solution are back-extracted with a hydrochloric acid solution containing thiourea. Alternatively, the silver-containing starting aqueous solution is contacted with beads of a porous resin bearing the thiophosphate compound so that the silver ions are selectively adsorbed on the resin beads and then the silver ions are leached out of the resin beads with an organic solvent.

Abstract: A process for removing and recovering ammonia from the organic extraction phase in a metal liquid-liquid extraction process in which at least one ammoniacal aqueous solution (either a leach feed solution containing the metal to be extracted or an aqueous stripping solution employed to strip the metal values from the organic phase) is contacted with the organic phase which comprises a water insoluble, water immiscible hydrocarbon solvent solution of a water insoluble organic extractant for the metal.

Abstract: A method of biotreating a solid material to remove an undesired compound using a nonstirred surface bioreactor is provided. According to the method the surface of a plurality of coarse substrates is coated with a solid material to be biotreated to form a plurality of coated coarse substrates. The coarse substrates have a particle size greater than about 0.3 cm and the solid material to be biotreated has a particle size less than about 250 .mu.m. A nonstirred surface reactor is then formed by stacking the plurality of coated coarse substrates into a heap or placing the plurality of coated coarse substrates into a tank so that the void volume of the reactor is greater than or equal to about 25%. The reactor is inoculated with a microorganism capable of degrading the undesired compound in the solid material, and the solid material is then biotreated in the surface bioreactor until the undesired compound in the solid material is degraded to a desired concentration.

Abstract: A method of reducing the entrainment of aqueous mineral acid solutions in organic extractants used in the solvent extraction of metals from the aqueous fluid is disclosed. The method comprises adding an effective, entrainment prevention amount of a water soluble cationic polymer having a molecular weight of from about 10,000 to about 500,000 to a metal rich aqueous mineral acid solution, immediately prior to, or during mixing with a metal poor organic extractant, and then recovering a metal poor aqueous mineral acid phase, and a metal rich organic extractant phase having a reduced level of entrainment of the aqueous mineral acid solution. In a preferred embodiment the metal is copper, and the polymer is poly(diallyldimethylammonium) chloride.

Abstract: The invention relates to a process for the selective recovery of catalysts used in the production of adipic acid by(a) separating adipic acid from the reaction solution,(b) exposing the resultant reaction solution to a sulfonated ion exchanger, thereby binding iron, copper, and vanadium ions to said sulfonated ion exchanger,(c) separating the ion-exchanger from the reaction solution,(d) washing the separated ion exchanger with nitric acid to obtain an acid eluate, and(e) exposing the acid eluate to an ion exchanger modified with aminophosphonic acid groups, thereby removing the iron ions from the acid eluate.

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: The present invention is directed to a process for recovering copper from a copper-containing material by pressure oxidation followed by solvent extraction and electrowinning. The copper-containing solution formed by pressure oxidation is diluted before solvent extraction and the raffinate solution from solvent extraction is neutralized to reduce the acid levels in the raffinate solution.

Abstract: Use of diethyl dodecylphosphonate (DEDP) for the extraction of acids and metal salts from aqueous solutions.

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: This invention is directed to a process for making copper metal powder from copper-bearing material, comprising: (A) contacting said copper-bearing material with an effective mount of at least one aqueous leaching solution to dissolve copper ions in said leaching solution and form a copper-rich aqueous leaching solution; (B) contacting said copper-rich aqueous leaching solution with an effective amount of at least one water-insoluble extractant to transfer copper ions from said copper-rich aqueous leaching solution to said extractant to form a copper-rich extractant and a copper-depleted aqueous leaching solution; (C) separating said copper-rich extractant from said copper-depleted aqueous leaching solution; (D) contacting said copper-rich extractant with an effective amount of at least one aqueous stripping solution to transfer copper ions from said extractant to said stripping solution to form a copper-rich stripping solution and a copper-depleted extractant; (E) separating said copper-rich stripping soluti

Abstract: An improved process is described for the recovery of copper from an aqueous feed solution using solvent extraction and electrowinning in which the electrowinning is conducted in a first step wherein the electrolyte is flowing perpendicular to the cathode surface without auxiliary mixing of the electrolyte between electrodes, and a second step wherein the electrolyte is flowing parallel to the cathode surface. In a second embodiment, solvent extraction of copper and solvent extraction of acid are conducted in alternate steps to allow more complete recovery of copper.

Abstract: The present invention relates to water-soluble polymers and the use of such water-soluble polymers in a process for the displacement of the cyanide ions from the metal ions within metal-cyanide complexes. The process waste streams can include metal-cyanide containing electroplating waste streams, mining leach waste streams, mineral processing waste streams, and related metal-cyanide containing waste streams. The metal ions of interest are metals that give very strong complexes with cyanide, mostly iron, nickel, and copper. The physical separation of the water-soluble polymer-metal complex from the cyanide ions can be accomplished through the use of ultrafiltration. Once the metal-cyanide complex is disrupted, the freed cyanide ions can be recovered for reuse or destroyed using available oxidative processes rendering the cyanide nonhazardous.

Abstract: A process is disclosed for removing impurity elements, such as arsenic, and if necessary antimony, iron or bismuth, from valuable metal containing, such as copper containing, strongly mineral acid solutions by way of solvent extraction with organic solutions of hydroxamic acids, and for selectively stripping the impurity elements therefrom. Antimony, iron or bismuth are stripped with complexing acids, and arsenic is stripped with an aqueous solution containing valuable metal ions at a pH value in the 1.5 to 5 range, a higher pH than the original valuable metal containing aqueous acid solution.

Abstract: Apparatus combination and system for reducing use of fresh water in a photoprocessing operation by recirculation of the wash water to the photoprocessing operation via a silver recovery system. Wash water is periodically discharged to waste and a like amount of fresh water is added to the system which serves to reduce the concentration of thiosulfate ions in the wash water.

Abstract: The present invention, relates to the recovery of zinc values from an acidic solution containing hydrocyanic acid. The zinc is recovered as complex zinc cyanide anions which may, if desired, be recycled for the (selective) preliminary removal or separation of adsorbed copper values from an (strong or weak base) anion exchange material, the anion exchange material additionally being loaded with adsorbed cyanide complexes of precious metal values such as gold and silver. The invention, further relates to the recovery of cyanide values associated with copper cyanide complexes which are adsorbed on or taken up by an (strong or weak base) anion exchange material; the recovered cyanide values, for example, being available for recycling to a cyanide leach stage for leaching additional metal values from an ore or the like.

Abstract: Three new types of chelating resins containing nitrogen and sulfur or oxygen atoms as coordination atom were synthesized by the reaction of a polymer bearing amino (--NH.sub.2) or imino (.dbd.NH) groups as reaction sites with a substitutive derivative of epithiopropane or epoxypropane. These resins exhibited excellent adsorption properties for noble metals.

Abstract: A composition comprising a crosslinked, highly porous body derived from a water-soluble hydrogel polymer, said porous body being characterized in that it has an open-celled three-dimensional lattice structure, a density of less than about 1.0 g/cm.sup.3, a surface area of equal to or greater than about 300 m.sup.2 /g, a compression strength of equal to or less than about 10 percent yield at 300 psi, and an average pore diameter of less than about 500 Angstroms, wherein said hydrogel polymer is selected from the group consisting of alginates, gums, starch, dextrins, agar, gelatins, casein, collagen, polyvinyl alcohol, polyethylenimine, acrylate polymers, starch/acrylate copolymers, and mixtures and copolymers thereof; and a metal extractant.The composition may be used in removing and/or recovering metal ions from aqueous streams.

Abstract: The invention is for a process of removal of dissolved heavy metal cation contaminants from an organic solution. The process of the invention involves providing a chelating ion exchange resin modified by removal of sodium ions therefrom and contacting said organic solution with said modified exchange resin for a time sufficient to remove ionic metal impurities. The invention is useful for removal of ionic contaminants from organic solutions requiring high purity.

Abstract: An improved process for removal of metal ions from aqueous solutions is disclosed. Removal of metal ions from aqueous solution, particularly from metal plating waste streams, is achieved by the combined use of polyamines, at levels less than the stoichiometric amount of metal ion, and cation exchangers. Treatment of waste streams with low levels of triethylenetetramine followed by contact with a strong acid cation exchange resin is especially effective in the removal of copper from metal-containing waste streams.

Abstract: Process for biolixiviating minerals from copper sulfides and also from their flotation concentrates, characterized by the use of biolixiviation through indirect contact as well as separation and improvement of the chemical and biological steps of the biolixiviation process. In the chemical step, a low concentration of ferric sulfate is used as the lixiviating agent. In the biological step, bacterial films of Thiobacillus ferrooxidans attached to an inert solid are used to regenerate the lixiviating agent by converting the ferrous ion into ferric ion through oxidation. The regenerated agent is then recycled to the lixiviation reactor. The biolixiviation process permits complete extraction of the copper contained in the ore and results in a lixiviation liquor which contains all the copper charge and a low concentration of ferric sulfate similar to the low concentration of ferric sulfate used initially.

Abstract: A pulp with ph=9.5 to 11.5, resin, and cyanide KCN is fed to a reaction zone. KCN is in a concentration of CN.sup.- ions in the liquid phase of the pulp from about 0.1 to about 10 g/l, which is maintained constant. The sorbent is in an amount providing its concentration 1 to 1.5% of the reaction zone volume. The leaching procedure produces a sorbent with impurities and rich in gold and silver, and a cyanic pulp depleted of gold and silver. Then, the sorbent rich in gold and silver is separated from the cyanic pulp. The saturated sorbent with impurities is processed in the desorption zone in two stages by passing therethrough a sulfuric acid solution of thiourea, the volume of the solution comprising 10 to 15 volumes of said sorbent. The sulfuric acid solution of thiourea is in an amount of 30% to 50% of said solution volume. A sulfuric acid solution of thiourea rich in gold and silver and a sorbent depleted of gold, silver and impurities is obtained.

Abstract: An efficient method is proposed for the recovery of gold value contained in an aqueous solution even in a very low concentration of the ppb level. Namely, an aqueous acidic solution containing gold value in the form of complex gold anions, e.g., chloro complex anions of gold, is contacted with a solid ion exchanger which is prepared by the adsorption of a 2-hydroxyethyl tri(C.sub.8-12)alkyl ammonium halide on porous resin beads of a polymer of methacrylic acid ester so that the complex gold anions are adsorbed by the ion exchange reaction to form ion pairs with the quaternary ammonium cations. The thus adsorbed complex gold anions coupled with the quaternary ammonium cations can be eluted out of the adsorbent with an organic solvent such as alcohols and ketones in a quantitative yield of recovery.

Abstract: A process for separating a radionuclide such as radioactive Cu-64 from a mixture containing the radionuclide and a precursor element from which the radionuclide is formed. A weak acid solution is prepared which contains the mixture of the radionuclide and the element. The solution is contacted with a ligand which preferentially forms a complex with the radionuclide relative to the precursor element. The radionuclide complexed to the ligand is separated from the precursor element and released from the ligand by contacting the ligand with an acid.

Abstract: A method for the recovery of a metal from an organic complex thereof, said method comprising treating the complex with a weakly acid aqueous solution of an alkali metal or alkaline earth metal chloride having a chloride content of at least 4 molar whereby said complex is decomposed and metal ions are transferred to the aqueous solution.

Abstract: A method for the recovery of a metal from an organic complex thereof, said method comprising treating the complex with a weakly acid aqueous solution of an alkali metal, an alkaline earth metal or ammonium chloride having a chloride content of at least 4 molar whereby said complex is decomposed and metal ions are transferred to the aqueous solution.