Abstract: Prior to evaporative crystallization of ammonium tungstate solutions to give ammonium paratungstate (APT), an aluminum compound, e.g. aluminum sulfate solution, is added to precipitate silicon and phosphorus impurities. The yield of crystallized ammonium paratungstate is thereby increased.

Abstract: Chromium and vanadium can be co-extracted from alkaline solutions or leach liquors containing these metals using quaternary amine solvent mixtures. The alkaline leach liquors usually are derived by leaching of calcined ores or concentrates. The loaded solvent mixture is scrubbed with chromium solution to remove all metals except chromium, and the chromium is then recovered from the solvent phase. The vanadium can be recovered from the scrub liquor. Recovery of aluminum is also possible.

Abstract: Cobalt is recovered in substantial amounts from spent catalyst particles comprising cobalt components supported on alumina or other aluminum-containing refractory oxides. The process comprises contacting the catalyst with sulfuric acid, then subjecting the catalyst to oxidation in an oxygen-containing atmosphere under conditions of elevated temperature, and again contacting the catalyst with sulfuric acid to extract cobalt. Molybdenum, if present on the catalyst, is recovered with the cobalt, as are other metals, such as nickel and tungsten.

Abstract: A method of recovering molybdenum from the catalyst residue derived from the process of epoxidizing olefins is disclosed. The catalyst residue, in semi-solid form or as a solution diluted in an organic solvent, is contacted with an aqueous solution of an oxidizing agent such as hydrogen peroxide, nitric acid, or sodium hypochlorite to transfer the molybdenum to the aqueous solution. The molybdenum is thereafter isolated directly from the aqueous solution or, alternatively, from the aqueous solution following preconcentration by liquid-liquid or liquid-solid extraction.

Abstract: A process for extracting tungsten values from an aqueous phase into an organic phase, comprises(a) providing an aqueous phase containing tungsten values dissolved therein, and having an initial pH of about 2.2 to about 4.0,(b) providing an organic phase depleted in tungsten and containing a secondary amine or tertiary amine extractant, a modifier, and the balance a liquid hydrocarbon solvent,(c) extracting tungsten values from said aqueous phase into said organic phase in a plurality of extraction stages operating in countercurrent fashion, and(d) recovering the organic phase enriched in tungsten values and an aqueous raffinate having a pH of about 0.3 to about 4.5.

Abstract: In the process of recovering molybdenum from a spent catalyst solution obtained from a crude reaction product of a molybdenum catalyzed epoxidation of an olefin with an organic hydroperoxide from which crude reaction product epoxide and an alcohol corresponding to the hydroperoxide is removed, the improvement comprises removing and recovering dissolved molybdenum as a high molybdenum content solid by subjecting the spent catalyst solution to a liquid-to-liquid extraction with an aqueous extract to form a two phase system, separating the molybdenum-rich aqueous extract and precipitating therefrom a high molybdenum content solid by heating the aqueous extract in the presence of hydrogen sulfide or a water soluble sulfide salt.

Abstract: The process of separating components of a crude reaction mixture obtained from a molybdenum-catalyzed hydroperoxide epoxidation of an olefin wherein the product epoxide and an alcohol corresponding to the hydroperoxide used are removed from the reaction mixture leaving a spent catalyst solution and subjecting the spent catalyst solution to a liquid-to-liquid solvent extraction to separate dissolved molybdenum values is improved by solvent extracting the spent catalyst solution with an extracting medium consisting essentially of water and a water immiscible organic solvent to form a two phase system and then separating the molybdenum-rich aqueous phase extract from the organic phase extract. The molybdenum-rich aqueous phase extract may be treated to recover the molybdenum as a solid or the extract may be treated to obtain an active molybdenum catalyst suitable for reuse as a catalyst in a hydroperoxide epoxidation reation.

Abstract: Basic sodium tungstate leach liquor is treated to reduce the concentration dissolved therein of silica, phosphorus and fluorine impurities in a process which comprises providing a small but effective amount of magnesium in the liquor to maximize removal of silica and phosphorus from solution in the liquor while maintaining the liquor temperature between about 60.degree. C. and about 100.degree. C. and the liquor pH between about 9 and about 11, filtering the liquor, adjusting the liquor pH to between about 6 and about 8 and the liquor temperature to between about 20.degree. C. and about 60.degree. C., and then providing a small but effective amount of aluminum hydroxide in the filtered liquor to maximize removal of fluorine from solution in the liquor while maintaining the liquor temperature between about 20.degree. C. and about 60.degree. C. and the liquor pH between about 6 and about 8.

Abstract: A lubricating oil additive is produced by contacting an aqueous slurry of ammonium paratungstate with an organic phase comprising a major proportion by weight tertiary alkyl amines having the formula C.sub.n H.sub.2n+1 NH.sub.2, where n is from 18 to 22, to extract the tungsten into the organic phase from the aqueous phase while solid ammonium paratungstate is being solubilized into the aqueous phase. The aqueous phase is heated to drive off water so as to form the resulting lubricating oil additive.

Abstract: The process is described wherein molybdenum values are separated from an aqueous solution containing tungsten. The molybdenum is converted to a thiomolybdate ion and the resulting solution is contacted with a suitable amount of organic extractant for a sufficient period of time to preferentially extract the thiomolybdate. The organic extractant including the thiomolybdate is separated from the aqueous solution comprising the unextracted tungsten values. The molybdenum values are stripped from the separated organic extractant by contacting with an aqueous solution containing sufficient amount of an oxidizing agent suitable for oxidizing the thiomolybdate complex ion to the molybdate ion which in turn is soluble in the aqueous solution. The organic extractant is then recycled for extracting the thiomolybdate complex ion and the molybdate ion may be recovered from the aqueous solution by conventional methods.

Abstract: A process for recovering tungsten from low level sources such as naturally occurring brines in a form substantially free of contaminating boron comprises adjusting the pH of the source solution to a value below about pH 8, contacting the pH-adjusted solution with an ion exchange resin, preferentially eluting the tungsten values in an aqueous eluate, extracting the eluate solution with an organic extractant comprising o-mercaptobenzoic acid, a quaternary alkylammonium salt and an inert organic solvent, and stripping the tungsten-loaded organic extractant solution with an aqueous basic stripping solution.

Abstract: A process for recovering concentrated, purified tungsten values, such as ammonium paratungstate, from a brine containing minor amounts of soluble tungsten and a substantial concentration of impurities, the brine having a pH in the range of from about 7.0 to about 8.5. In general, the process comprises: contacting the brine with a substantially water-insoluble ion exchange resin to adsorb the soluble tungsten; eluting the adsorbed tungsten values from the ion exchange resin; treating the eluate to convert the tungsten values to an extractable species; recovering the extractable species of tungsten values from the eluate to substantially concentrate the tungsten values; contacting the concentrated tungsten values with an extractant to substantially load the extractant with the concentrated tungsten values; and recovering from the extractant a product having concentrated, purified tungsten values.

Abstract: A recyclable process for the recovery of tungsten from low level aqueous sources comprises adjustment of the pH of the source solution to a value below about pH 6, extraction of the tungsten values into an organic phase comprising a chelating agent, an organic transfer agent, and an inert organic solvent. Preferred chelating agents include vicinally disubstituted aromatic compounds in which the substituents are selected from amino, carboxyl, hydroxyl, and sulfhydryl.

Abstract: Rhenium and tungsten are recovered from a rhenium tungsten alloy by electrochemically dissolving the alloy in substantially 4 to 5 normal sodium hydroxide to form a rhenium-containing solution, solvent extracting the rhenium-containing solution with an organic heteroatom-containing solvent (e.g. pyridine) or acetone to form a second solution of the solvent containing rhenium, distilling the solvent from the second solution to form a raffinate containing rhenium, adding sulfuric acid to the raffinate to adjust the pH thereof to about 1, extracting tungsten from the raffinate with a solution of trioctylamine in kerosene containing octyl alcohol, and subjecting the raffinate containing sodium perrhenate to ion exchange to eventually convert it to ammonium perrhenate.

Abstract: Disclosed is a process for removing molybdenum values from aqueous solutions containing tungsten values comprising sulfidizing said solution to an extent sufficient to convert substantially all of the molybdenum values to a thiomolybdate species, said sulfidizing being substantially less than the extent necessary to convert substantially all of said tungsten values to a thiotungstate species and contacting the resulting solution containing the thiomolybdate complex ion with a suitable amount of an organic extractant for a sufficient period of time to preferentially extract the thiomolybdate complex ion into the organic extractant, said organic extractant comprising an aromatic organic solvent and a quaternary ammonium compound of the formula R.sub.3 (CH.sub.3)N.sup.+ A.sup.-, wherein R is an alkyl group having from about 8 to 10 carbon atoms and A is an anion derived from a mineral acid.

Abstract: In a resin sorption process for recovering tungsten from solutions containing high levels of contaminating boron by employing a resin copolymer of 8-hydroxyquinoline, a polyamine, resorcinol, and formaldehyde (HPRF resins), the improvement comprises a two step desorption of metal values from the loaded resin consisting of a first step of washing the loaded resin with a solution of a weakly acidic salt to remove a portion of the boron from the loaded resin, followed by a second step of washing the loaded resin with a solution of a weakly basic salt to remove a portion of the tungsten from the loaded resin, whereby the tungsten recovered is substantially free of contaminating boron.

Abstract: The invention relates to the production of tungsten having a low impurity content of molybdenum from impure minerals such as scheelite.An aqueous acidic feed solution containing both molybdenum and tungsten, and also containing enough hydrogen peroxide to depolymerize heteropolymers of tungsten and molybdenum and prevent precipitation in the extractant, is contacted with an extractant composition comprising an organic phosphoric acid, a trialkyl phosphate and a tri-alkyl phosphine oxide in an hydrocarbon diluent. By selecting an appropriate combination of pH and hydrogen peroxide content of the feed, contents of the components of the extraction composition and temperature of extraction, selective extraction of molybdenum can be obtained. In some particularly preferred embodiments, the feed pH is in the range of 0.85 to 1.5, the mole ratio of hydrogen peroxide to tungsten and molybdenum is 0.6 to 1.0, the temperature of extraction is in the range 12.degree. to 20.degree. C.

Abstract: Molybdenum is recovered from an ammonium molybdate solution containing phosphate anions by digesting in an ammonium molybdate solution at least one water-soluble compound of at least one metal selected from the group consisting of aluminum, calcium, iron and magnesium in small but effective amounts to precipitate at least about 50% of the phosphate anions for a time sufficient to precipitate the phosphate anion, separating the phosphate precipitate from the ammonium molybdate solution, then acidifying the ammonium molybdate solution with at least one mineral acid selected from the group consisting of sulfuric acid and nitric acid to lower the pH value of the solution to between about 2.5 and about 4.5 to precipitate ammonium polymolybdate, and calcining the ammonium polymolybdate at a temperature below about 750.degree. C. to produce a molybdenum trioxide product.

Abstract: The method for recovering metals of Groups V-VI of the periodic system from solutions and pulps according to the present invention is effected by means of a selective ion-exchange resin which is the reaction product between a polyhydric phenol with formaldehyde with a specific surface area of from 50 to 600 m.sup.2 /g, pore volume of from 0.2 to 2.3 cm.sup.3 /g, content of hydroxy groups of at least 11.3 mg-equiv/g.

Abstract: A method of removing chromium ion from an aqueous solution of an organic acid of an acid concentration of up to 95% which comprises treating the solution with a cation exchange resin at a temperature higher than 55.degree. C.

Abstract: The efficiency of an extraction process using a dialkyl phosphoric acid as an active extractant for separating extractable soluble metallic values from an aqueous solution is improved by the presence of a sufficient amount of a dialkyl naphthalene sulphonic acid as a modifier for the extractant.

Abstract: An 8-hydroxyquinoline-resorcinol-formaldehyde ion exchange resin, in bead form, is employed for sorption of tungsten from alkaline solutions such as brines.

Abstract: A process for recovering heavy metal ions or heavy metal ions and halogen values from a solution comprising a lower aliphatic monocarboxylic acid, which comprises the steps of:(1) contacting a lower aliphatic carboxylic acid solution containing heavy metal ions or heavy metal ions and halogen values with an anion exchange resin, at least 60% of the ion-exchange groups of said anion exchange resin being in the bromide or chloride state, while the water concentration in the lower aliphatic monocarboxylic acid solution has been adjusted to a level lower than 20% by weight, thereby to adsorb the heavy metal ions or the heavy metal ions and the halogen values on the anion exchange resin; and(2) desorbing the adsorbed heavy metal ions or the adsorbed heavy metal ions and the adsorbed halogen values from the anion exchange resin by elution with an eluent.

Abstract: Method for the recovery of high purity Cr.sub.2 O.sub.3 from a Na.sub.2 CrO.sub.4 or Na.sub.2 Cr.sub.2 O.sub.7 solution by producing (NH.sub.4).sub.2 CrO.sub.4 by solvent extraction, evaporating the aqueous (NH.sub.4).sub.2 CrO.sub.4 and igniting the resulting solids to provide high purity Cr.sub.2 O.sub.3.

Abstract: A liquid-liquid extraction process is disclosed, in which an aqueous solution, containing metal ions, is contacted with an organic liquid substantially insoluble in water. The organic liquid contains two water-insoluble reagents, viz. a diester of dithiophosphoric acid and an organic phosphate, in a preferred volume ratio of between 1:10 and 2:1. The organic liquid may also contain a diluent for the reagents.

Abstract: Molybdenum is recovered from dilute, ammoniacal, molybdenum containing solutions by adding ferrous ions to the solution to precipitate an iron hydroxide-ammonium molybdate complex. The precipitate is separated from the aqueous raffinate and is treated with acid to resolubilize the molybdenum in the complex. Molybdenum values are recovered from the resulting acid solution by ion exchange. The aqueous raffinate is purged of iron and is reused.

Abstract: Molybdenum is separated from molybdenum-containing activated charcoal or char also containing small amounts of uranium obtained as a by-product in uranium leaching processes by stripping with an alkaline solution to provide a molybdenum-containing solution containing substantially less than 500 ppm U.sub.3 O.sub.8.

Abstract: An extraction process is described for the selective separation of bivalent metal ions belonging to the group Cu, Co, Ni and Zn in aqueous solution of Cu- and Ni-ions, Cu- and Zn-ions or Cu- and Co-ions, wherein there is used as the extraction medium one or more unsaturated fatty acids, optionally in solution and/or in admixture with saturated fatty acids and an aliphatic oxime.

Abstract: A process and apparatus for obtaining a more concentrated solution of components such as chromium containing anions by the use of ion exchange beds. A solution containing the component to be concentrated is passed through a first bed in which the component is taken up. A second solution containing a component of opposite charge from the first component is passed through the first bed to take up the component from the first bed and then through a second bed capable of taking up the second component from the solution. The second solution is passed from the first bed directly to and through the second bed, and both beds are rinsed following passage of the second solution therethrough by passing a rinse solution through the second bed and then directly to and through the first bed in a direction opposite to the direction in which said second solution passed through the beds.

Abstract: A process is disclosed wherein essentially all of the rhenium can be removed from an aqueous solution of molybdenum without the extraction of molybdenum using a particular solvent extraction solution. The extraction solution consists essentially of quaternary ammonium compound and at least about 50 percent by volume of a highly aromatic solvent which dissolves a quaternary ammonium-rhenium complex to the extent of at least 0.1 percent by volume selected from the group consisting of benzene and an aromatic solvent containing primarily lower alkyl benzenes having molecular weights of either 106, 120, 134 or 148 with minor amounts of relatively long chain aliphatic hydrocarbons containing greater than 8 carbon atoms and minor amounts of napthalene.

Abstract: A resin for sorption of tungsten is prepared by copolymerization of 8-hydroxyquinoline, a polyamine, resorcinol and formaldehyde. The resin finds particular utility for recovery of tungsten from alkaline brines.

Abstract: A tungsten extraction process wherein tungsten values are extracted from an aqueous alkali metal tungstate solution by an organic extractant, then stripped from the extractant is improved by using an organic solution consisting essentially of from about 6 to about 10 percent by volume an extractant that is a mixture of trialkyl amines wherein the major constituent is tri-isooctyl amine and from about 90 to about 94 percent by volume of a solvent that is a mixture of alkyl benzenes having molecular weights of either 120, 134 or 148.

Abstract: A process for treating very dilute solutions containing ecologically noxious heavy metal ions, in which the solutions are made acceptable for return to the environment, and the typically valuable heavy metal present in the solution is recovered at an economic profit. The dilute solution is flowed through an ion exchange resin, as a cross-linked polystyrene having quaternary ammonium functional groups which hold the heavy metal ions, allowing an ecologically benign effluent to return to the environment or the water to be re-used in industrial processing. Typically, an alkali metal halide is subsequently placed in contact with the resin to recover the heavy metal ion for subsequent reduction to a solid.

Abstract: A method for recovering nonferrous metal values from hydroxide sludge wastes containing same by first chlorinating the aqueous waste to oxidize the chromium therein, separating the insoluble components therefrom and treating the resulting Cr(VI) solution in a fixed bed anion exchanger to separate the Cr(VI) from the solution, separating the copper from the aqueous solution by liquid-liquid extraction, separating the zinc from the copper-free solution by liquid-liquid extraction, precipitating and separating the aluminum in the form of hydroxide from the zinc-free solution and then separating the nickel from the aluminum-free solution by liquid-liquid extraction, and recovering the nonferrous metals from the respective solutions and precipitates by conventional procedures.

Abstract: From roasted products of used catalysts from hydrotreatment desulfurization of petroleum, valuable molybdenum, vanadium, cobalt and nickel are recovered easily and a high percent recovery by means of a combination of simple chemical procedures and also inexpensive chemicals. The recovered metal components can be reused for preparing new catalysts and the like.

Abstract: Process for the removal of chromium and zinc corrosion inhibitor compounds from cooling tower blowdown streams, comprising contacting the water of said streams first with a weakly basic anion exchange resin and then with a weakly acidic cation exchange resin.

Abstract: A process for recovery of reusable chromic acid from waste chromic acid solution containing impurities, which process comprises a first step in which the solution containing chromic acid is introduced into the cathode compartment in an electro-dialysis process and free chromic acid or chromate ions in the above solution are transferred to the anode compartment, a second step in which H.sub.2 SO.sub.4 is added in at least equivalent amounts to the heavy metallic ion contained in the outlet solution, in which chromic acid ion concentration is reduced, in order to convert chemical species of the contained metallic ion and increase the H.sup.+ ion concentration and then chromate ions in the resultant solution are extracted into an organic phase with contact of an organic solvent (A), and a third step in which residual amounts of chromic acid ion remaining in the aqueous raffinate from the second step are extracted into an organic phase with contact of an organic solvent (B).

Abstract: To obtain highly purified, lamp grade ammonium paratungstate crystals from any of several different tungsten ores, the ore is reduced to finely divided status and slurried in heated HCl solution to convert tungsten values to WO.sub.3.H.sub.2 O. Recovered tungstic oxide is washed and dissolved in heated aqueous solution of sodium carbonate or sodium hydroxide with the pH maintained at about 8 to 8.5 to form soluble sodium tungstate. Sodium hydroxide is added to raise the pH to about 10.5 to 11.5, and magnesium chloride is added in amount sufficient to somewhat neutralize the solution. Sodium hydroxide is added to raise the pH to about 10.5 to 11.5 to precipitate as hydroxide the magnesium and additional metallic impurities. At least one of ammonium sulfide and thioacetamide is and the heated solution is acidified to a pH in the range from about 2 to 3 to precipitate any molybdenum as MoS.sub.3.

Abstract: New chelate exchange resins capable of selective recovery of copper, nickel, and other valuable metals from an acidic aqueous leach liquor are prepared by reacting a crosslinked haloalkyl polymer matrix resin (I) with certain aminopyridines (II) to give a resin (III) ##STR1## with pendent methyleneaminopyridine groups attached to the matrix resin. Particularly useful resins are obtained by reacting chloromethylated styrene-divinylbenzene copolymer beads with an aminomethylpyridine, such as 2-picolylamine, N-methyl-2-picolylamine, N-(2-hydroxyethyl)-2-picolylamine, N-(2-methylaminoethyl)-2-picolylamine, or bis-(2-picolyl)amine. At a typical copper ore leach liquor pH of about 2, the picolylamine resins will absorb 15-30 mg copper/ml resin with a 5-10 fold selectivity for copper over ferric iron.

Abstract: Process for recovering molybdenum-99 from a matrix which has been irradiated with neutrons and contains fissionable materials and fission products, wherein the matrix is decomposed in an aqueous alkali hydroxide solution and the molybdenum-99 and part of the fission products are dissolved, the solution containing the molybdenum-99 is separated from a residue of particles containing at least actinides and lanthanides and is treated with thiocyanate ions to form a molybdenum complex. In the process, the alkali solution containing molybdenum in the form of molybdenum (MoO.sub.4.sup. --) is conditioned with an iodine reduction agent. Mineral acid is added to the alkali solution. The molybdenum contained in the acidfied solution is reduced to form three-valent molybdenum Mo(III) and the Mo(III) is complexed with SCN.sup.- ions to form [Mo(SCN).sub.6 ].sup.3- ions. The [Mo(SCN).sub.6 ].sup.3- ion containing solution is treated with a previously-conditioned, organic ion exchanger to selectively sorp the molybdenum.

Abstract: Process for recovering molybdenum-99 from a matrix which has been irradiated with neutrons and contains fissionable materials and fission products, wherein the matrix is decomposed in an aqueous alkali hydroxide solution and the molybdenum-99 and part of the fission products are dissolved, the solution containing the molybdenum-99 is separated from a residue of particles containing at least actinides and lanthanides and is treated with thiocyanate ions to form a molybdenum complex. In the process, the alkali solution containing molybdenum in the form of molybdate (MoO.sub.4.sup.--) is conditioned with an iodine reduction agent. Mineral acid is added to the alkali solution. The molybdenum contained in the acidified solution is reduced to form three-valent molybdenum Mo(III) and the Mo(III) is complexed with SCN.sup.- ions to form [Mo (SCN).sub.6 ].sup.3- ions. The acid solution which contains [Mo (SCN).sub.6 ].sup.

Abstract: A process for recovering tungsten values in the form of ammonium paratungstate from tungsten ores and ore concentrates, particularly wolframite ores and ore concentrates, incorporating a plurality of steps for necessary removal of impurities and formation of the product ammonium paratungstate. The steps of the process include grinding, caustic leaching, filtrations, chemical treatment including acidification particularly for the removal of silica impurities, further filtration, solvent extraction of the tungsten values, stripping of the tungsten values from the solvent solution in the form of ammonium paratungstate, and recovery of the ammonium paratungstate product. The caustic leaching step may be carried out in the substantial absence of oxygen.

Abstract: The present invention relates to the recovery of uranium from carbonate leach solutions. More particularly, it relates to the recovery of uranium from ammonium carbonate leach solutions having molybdenum as an impurity.

Abstract: Production of titanium dioxide which is characterized by recovery of reusable H.sub.2 SO.sub.4, highly pure Fe oxide and hydroxide and fractional recovery of Mn, V and Cr, etc., from FeSO.sub.4. nH.sub.2 O and waste acid of 20 - 40% H.sub.2 SO.sub.4 containing abundant heavy metallic ions, which are by-produced in the production of TiO.sub.2 by dissolution of Ti raw materials such as ilmenite, steel production slag, such as electric furnace slag, convertor slag with H.sub.2 SO.sub.4.

Abstract: A process for producing a high purity ammonium heptamolybdate and/or ammonium dimolybdate product by which a particulated molybdenum oxide concentrate is purified to remove contaminating metal cations, whereafter it is leached with an ammoniacal leach solution to extract the molybdenum trioxide constituent therein as soluble ammonium molybdate compounds. The resultant ammoniacal leach solution is thereafter concentrated at an elevated temperature, whereafter at least a portion thereof is adjusted to provide an ammonia-to-molybdenum trioxide mol ratio ranging from about 0.86:1 to about 1.25:1, and the adjusted solution thereafter is cooled to effect a precipitation of ammonium heptamolybdate crystals which are separated and recovered, and the balance of the cooled solution is recirculated for admixture with additional ammoniacal leach solution.

Abstract: In this process metal ions such as Ag.sup.+, Pb.sup.2+, Co.sup.2+, Cu.sup. 2+, Fe.sup.3+, etc., are extracted through a porous membrane impregnated with the first extractant containing chelating agents. The membrane contacts with an extraction feed on one side, and with the second extractant on the other side, and the objective metal ions are transferred from the feed to the second extractant. Throughout the extraction process, the pH values of the extraction feed, the impregnated extractant solution, and the second extractant are kept in decreasing order.An apparatus used for the above objective is also provided by this invention.

Abstract: A process of separately recovering vanadium and molybdenum from an aqueous solution containing a vanadium compound is disclosed. The process comprises adjusting the pH of such a solution to a pH between 1.5 and 7, contacting the solution with a weakly basic anion exchanger in the salt form, eluting said anion exchanger with an ammonium hydroxide solution having a strength between about 1 and 4N, crystallizing the resulting ammonium vanadate, and separating the same from the vanadium and molybdenum solution obtained in said elution.

Abstract: A process is disclosed wherein essentially all of the rhenium can be removed from an aqueous solution of molybdenum without the extraction of molybdenum using a particular solvent extraction solution. The extraction solution consists essentially of a quaternary ammonium compound and at least about 50% by volume of a highly aromatic solvent which dissolves a quaternary ammonium-rhenium complex to the extent of at least 0.1% by volume.

Abstract: A chromic acid solution can advantageously be recovered from the waste water by a process which comprises passing the waste water successively through an anion-exchange column system consisting of two or more serially interconnected anion-exchange resin columns each packed with an anion-exchange resin thereby deionizing the waste water, and, in the course of this deionization treatment, column backwashing the first anion-exchange resin when the anion-exchange capacity thereof has fallen to the point where the influent to and the effluent from the first anion-exchange resin column have become substantially equal in terms of chromate ion content. In the course of the regeneration treatment, the waste water is diverted to enter the anion-exchange column system through the second anion-exchange resin column. After the regeneration treatment has been completed, the first anion-exchange resin column is put back into service in the anion-exchange system so as to serve as the last stage.

Abstract: The present invention relates to removal of chromate from an aqueous solution of an alkali metal chlorate and chloride, particularly sodium chlorate and sodium chloride in a selected ratio which has been obtained by the electrolysis of an aqueous solution of alkali metal chloride containing chromate in which the essentially chromate free aqueous solution of alkali metal chlorate and chloride contains the chlorate and chloride in essentially the same selected ratio. In the process the chromate containing aqueous solution of alkali metal chlorate and chloride is acidified with hydrochloric acid to a pH value not smaller than 0.5 and passed through an anionic ion exchange resin bed which has previously been saturated with alkali metal chlorate and chloride. The bed is then regenerated by passing an aqueous solution of an alkali metal hydroxide and alkali metal chloride therethrough to remove chromate therefrom.