Abstract: Processes are described for preparing pure ammonium molybdate from impure roasted molybdenum concentrates. An aqueous solution of sulfuric acid, ammonium sulfate, and ammonium persulfate is contacted with impure molybdenum concentrate to solubilize a major portion of the impurities. The resulting molybdenum concentrate is digested in ammonium hydroxide under conditions that maximize iron precipitation and removal. The resulting ammonium molybdate solution is separated from the sludge and further purified by chelating cation exchange resin in the ammonium form.

Abstract: Processes are described for preparing pure ammonium molybdate from impure roasted molybdenum concentrates. An aqueous solution of nitric acid, ammmonium sulfate, and ammonium nitrate is contacted with impure molybdenum concentrate to solubilize a major portion of the impurities. The resulting molybdenum concentrate is digested in ammonium hydroxide under conditions that maximize iron precipitation and removal. The resulting ammonium molybdate solution is separated from the sludge and further purified by chelating cation exchange resin in the ammonium form.

Abstract: A method is disclosed for removing tin from aqueous sodium tungstate solutions. The method involves adding ammonia to the sodium tungstate solution, adjusting the pH to above about 9.5 with an acid, adding magnesium chloride to form insoluble material containing the major portion of the tin, silicon, arsenic and phosphorus and a resulting sodium tungstate solution containing the major portion of the tungsten, and separating the insoluble material from the resulting solution.

Abstract: Processes are described for preparing pure ammonium molybdate from impure roasted molybdenum concentrates. An aqueous solution of nitric acid and ammonium nitrate is contacted with impure molybdenum concentrate to solubilize a major portion of the impurities. The resulting molybdenum concentrate is digested in ammonium hydroxide under conditions that maximize iron precipitation and removal. The resulting ammonium molybdate solution is separated from the sludge and further purified by chelating cation exchange resin in the ammonium form.

Abstract: A spent or scrap tungsten-containing, aluminosilicate catalyst material is blended with a silicate-containing, tungsten-bearing ore concentrate in amounts such that at least about 2.0% by weight of the total tungsten values in the mixture are present in the catalyst material, and then digested with an alkaline solution, e.g., sodium carbonate, under pressure and at an elevated temperature for a period of time sufficient to extract substantially all of the tungsten values from the mixture components. The presence of the catalyst material substantially suppresses the dissolution of silica in the leach liquor.

Abstract: In the disintegration of a chromite or chromium-containing residue, wherein the chromium-containing material is disintegrated with an alkaline compound in the presence of oxygen and a diluent at a temperature above about 800.degree. C. and thereafter leached, the improvement which comprises pre-roasting the chromium-containing material prior to addition of the alkaline compound. Pre-roasting can be effected at 400.degree. to 1200.degree. C. with addition of certain amounts of silica dioxide and/or aluminum oxide and such additives, depending on the chromium containing material, if still required, are added--prior to disintegration and leaching--in such a quantity to establish a ratio of SiO.sub.2 : AL.sub.2 O.sub.3 of about 2:1 and further a ratio, calculated on the basis of NaOH as the alkaline compound, of SiO.sub.2 : Na.sub.2 O of about 1:0.5 plus a Cr.sub.2 O.sub.3 : Na.sub.2 O ratio of about 1:2 to 1:4.

Abstract: A process is provided for recovering metal values from spent hydrodesulfurization catalyst, the process comprising forming in a pressure reactor an aqueous slurry of finely divided spent catalyst and sodium carbonate, the spent catalyst containing by weight about 2 to 10% Mo, up to about 12% V (e.g., about 2 to 10%), about 0.5 to 4% Co, up to about 10% Ni (e.g., about 0.5 to 5%), occluded oil, coke, sulfide sulfur and the balance essentially alumina. The amount of sodium carbonate employed is at least sufficient under oxidizing conditions to convert molybdenum and any vanadium present to soluble Na.sub.2 MoO.sub.4 and NaVO.sub.3 and to neutralize SO.sub.3 produced during oxidation, the amount of sodium carbonate being at least that required stoichiometrically. The slurry is heated to a temperature of about 200.degree. C. to 350.degree. C. (e.g., 275.degree. C. to 325.degree. C.) and a pressure of about 800 psig to 2500 psig (e.g.

Abstract: A process is provided for recovering molybdenum and tungsten separately from a sulfide cake containing the same along with arsenic as an impurity. The process comprises dissolving essentially all of the tungsten and molybdenum values contained in the cake in a caustic solution containing at least about 5 but not more than about 6 moles of sodium hydroxide per mole of tungsten plus molybdenum contained in the cake, separating insoluble material from the resulting leach solution and then precipitating one metal value from the group consisting of molybdenum and tungsten preferentially from the other.

Abstract: Tungsten and molybdenum are recovered from sulfur bearing material such as sulfide sludges by a pollution free process in which the sulfur bearing material is heated with agitation in an aqueous solution of sodium carbonate to form water soluble molybdenum and tungsten compounds without forming any appreciable amount of water soluble sulfur compounds. The reaction mixture is oxidized to convert partially reduced tungsten values or molybdenum values to sodium tungstate and sodium molybdate respectively. The liquid phase containing tungsten and molybdenum is separated from the solid phase containing free sulfur.

Abstract: The present invention relates to a process for recovery of uranium from a carbonate lixiviant additionally containing other contaminants such as molybdenum and silica, by adjusting the pH of the lixiviant to a value of at least 4 and treating the lixiviant to obtain a carbonate concentration of at least 50 ppm by weight. Subsequently the lixiviant is treated with an aqueous solution containing a sufficient amount of ferric iron to precipitate the contaminants without substantial precipitation with the uranium values. The precipitate is separated from the lixiviant. The treated lixiviant is passed through an ion exchange to retain uranium values.

Abstract: In a process for producing pure ammonium paratungstate from ammonium tungstate solutions containing tin, sulfide is added to the ammonium tungstate solution in an amount sufficient to form a soluble complex of the sulfide with the tin. The solution is then evaporated to a volume at which essentially all of the tungsten is in the form of insoluble ammonium paratungstate and essentially all of the tin is in the mother liquor in the form of a soluble complex along with other impurities. The solid ammonium paratungstate is then separated from the mother liquor by filtration.

Abstract: A method for recovering superalloy scrap is disclosed. The method involves oxidizing superalloy scrap in an aqueous acidic medium. The aqueous acidic medium has an oxidation potential sufficient to oxidize nonferrous additive superalloy elements to insoluble oxides thereof and to oxidize major superalloy constituents to aqueously soluble species. The insoluble solids from the aqueous solution are separated when the aqueous solution is extracted with an aqueously substantially insoluble tertiary amine to form an organic phase and an aqueous phase. The aqueous phase contains essentially nickel and chromium values. The organic phase is sequentially extracted with aqueous solutions which selectively solubilize individual metal value species to form individual aqueous solutions having substantially single metal value species therein. The metal value species solutions are processed to obtain substantially pure metals.

Abstract: A process for obtaining molybdenum as a useful product from aqueous solutions to be purified, according to claim 1 of French patent No.

Abstract: Process for the purification of an aqueous solution containing alkali metal carbonate, sulphate, and hydroxide or hydrogen carbonate and primarily one at least of the metals belonging to the group formed by vanadium, uranium and molybdenum, in the form of alkali metal salts, and mineral and/or organic impurities, said solutions resulting from an ore attack cycle and being taken off after extraction of the metal being sought, which comprises treating said solutions by means of lime at a temperature which is at most equal to the boiling temperature, to convert the carbonate and hydrogen carbonate present into alkali metal hydroxide, then effecting separation and washing of a first precipitate of calcium carbonate and a liquor which is enriched in respect of alkali metal hydroxide, concentrating it by evaporation to cause production of a second precipitate which essentially comprises alkali metal sulphate, separating it from the hydroxide-rich liquid phase, re-dissolving it in an aqueous medium and treating the

Abstract: Process for extracting molybdenum from aqueous solutions containing alkali metal carbonate, sulphate, hydroxide or hydrogen carbonate and, primarily, one at least of the metals belonging to the group formed by vanadium, uranium and molybdenum, in the form of alkali metal salts, and mineral and/or organic impurities, said solutions resulting from an ore attack cycle and being taken off after extraction of the metal being sought, in the form of a concentrate, wherein said solutions are caustified by the addition of a suitable amount of lime, converting the carbonate present into alkali metal hydroxide, a first precipitate is separated from the alkali metal hydroxide-rich liquor, said liquor is concentrated until the alkali metal hydroxide content is at most equal to 50%, to cause the production of a second precipitate formed by alkali metal sulphate and molybdate, which is solubilized in an aqueous recycle liquor, said re-dissolution liquor then being treated with sulphide ions and then acidified to give a pH-v

Abstract: Molybdenum catalyst employed in the epoxidation of an olefin with an organic hydroperoxide preferably the epoxidation of propylene, is recovered from the bottoms fraction by adding aqueous alkaline material to the bottoms fraction and separating the aqueous phase. The molybdenum can be recovered from the aqueous phase by acidification and precipitating it as an insoluble compound.

Abstract: Synthetic scheelite (calcium tungstate) having a low sulfur content is produced in high yield from an aqueous solution of sodium tungstate, that can be contaminated with sulfate ion dissolved therein, by digesting the solution with solid calcium sulfate whereby low-sulfur calcium tungstate precipitates. The solution remaining after filtration of the calcium tungstate product can be treated with calcium sulfate to precipitate additional purified calcium tungstate or to generate a calcium tungstate-calcium sulfate mixture that can be recycled for digestion with additional sulfate-contaminated sodium tungstate solution.

Abstract: Disclosed is a method of removing uranium from a slurry containing a water-insoluble molybdate and a Group II element, usually calcium. The pH of the slurry is raised with an alkali metal hydroxide and maintained at a level sufficiently high to solubilize insoluble molybdenum compounds. This will generally require a pH of at least 10 which can be achieved by adding sodium hydroxide. Carbonate ion is then added to the slurry in an amount at least sufficient to precipitate the cation of the insoluble molybdenum compound. And finally, the solid portion of a slurry, which now contains calcium carbonate and sodium uranate, is separated from the liquid portion, which contains a soluble molybdenum compound.

Abstract: Rapid recovery of molybdenum from an acid solution containing dissolved molybdenum is accomplished by using a multiple batch method. A first batch of ammonium molybdate precipitate is formed by diluting a first portion of acid with 1.5 times that volume of water, adding anhydrous ammonia, and seeding with ammonium molybdate particles while maintaining a temperature between 90.degree. C. and boiling. Subsequent batches of precipitate are formed by dissolving the previous precipitate in additional acid, similarly diluting as above, and adding anhydrous ammonia while maintaining temperature as above. All precipitates are coarse and fast settling.

Abstract: From a chlorate cell liquor containing an alkali metal chlorate, an alkali metal chloride and Cr(VI) ions, Cr(VI) ions are recovered by means of a combination of simple chemical procedures and re-used in an electrolysis step for manufacturing an alkali metal chlorate.

Abstract: The residue from a Mo-catalyzed coal liquefaction process is treated to recover the Mo in a form in which the Mo can easily be recycled and reused as a catalyst for coal liquefaction. The process includes intimately mixing the residue with alkali in excess of the stoichiometric amount required for water-soluble molybdate formation, subjecting the mixture to an oxidative roast at about 600.degree. C. to about 800.degree. C. for up to about one hour, leaching the roasted product with water to extract Mo values into solution, and then carrying out a series of steps involving acidifying and ammoniating the solution to form a Mo-bearing precipitate which is recovered and dissolved in aqueous ammonium hydroxide to form a solution which can be applied to coal to catalyze coal liquefaction.

Abstract: Tungsten is recovered from tungsten ore concentrates in the form of sodium tungstate by a basic process in which ground ore is first digested in a sodium hydroxide solution followed by diluting the solution to dissolved sodium tungstate separating the solution from the caustic insoluble sludge and crystallizing soluble sodium tungstate, wherein the present invention permits improved recovery of tungsten from difficult to process ores by the process steps of comminuting said tungsten ore concentrate to a particle size less than about 200 mesh, adding the comminuted ore to an aqueous solution of sodium hydroxide at a temperature from about 10 to about 30 degrees centigrade, dispersing said comminuted ore in the aqueous solution of sodium hydroxide prior to digestion, digesting at a temperature of from about 75.degree. C. to about 150.degree. C.

Abstract: Tungsten is recovered from tungsten ore concentrates in the form of sodium tungstate by a basic process in which ground ore is first digested in a sodium hydroxide solution followed by diluting the solution to dissolve sodium tungstate separating the solution from the caustic insoluble sludge and crystallizing soluble sodium tungstate, wherein the present invention permits improved recovery of tungsten from difficult to process ores by the process steps of comminuting said tungsten ore concentrate to a particle size less than 325 mesh, adding said comminuted ore to aqueous sodium hydroxide at a concentration of at least 10 molar and digesting at a temperature of from about 75.degree. C. to 150.degree. C. for a sufficient period of time to convert substantially all of the tungsten values to soluble sodium tungstate, and diluting the mixture to reduce the sodium hydroxide concentration to between about 4.5 and 5.5 molar at a temperature below about 90.degree. C.

Abstract: Tungsten is recovered from tungsten ore concentrates in the form of sodium tungstate by a basic process in which ground ore is first digested in a sodium hydroxide solution followed by diluting the solution to dissolve sodium tungstate separating the solution from the caustic insoluble sludge and crystallizing soluble sodium tungstate, wherein the present invention permits improved recovery of tungsten from difficult to process ores by the process steps of drying the insoluble sludge portion, comminuting the dried sludge to a particle size less than about 200 mesh, and dissolving said comminuted sludge in 4.5-5.5 molar NaOH to recover substantially all of the tungsten values.

Abstract: Tungsten is recovered from tungsten ore concentrates in the form of sodium tungstate by a basic process in which ground ore is first digested in a sodium hydroxide solution followed by diluting the solution to dissolve sodium tungstate separating the solution from the caustic insoluble sludge and crystallizing soluble sodium tungstate, wherein the present invention permits improved recovery of tungsten from difficult to process ores by the process steps of comminuting said tungsten ore concentrate to a particle size less than about 200 mesh, dispersing the comminuted ore to separate agglomerated particles, adding the dispersed ore to aqueous sodium hydroxide at a concentration of at least 10 molar and digesting at a temperature of from about 75.degree. C. to 150.degree. C. for a sufficient period of time to convert substantially all of the tungsten values to soluble sodium tungstate, and diluting the mixture to reduce the sodium hydroxide concentration to between about 4.5 and 5.

Abstract: A process for the soda ash digestion of scheelite concentrates is provided, the process comprising forming a slurry of a scheelite concentrate in an aqueous sodium carbonate solution and then digesting the slurry in an autoclave at an elevated temperature of at least about 180.degree. C. The concentration of the Na.sub.2 CO.sub.3 solution is substantially inversely correlated to the digestion temperature and substantially directly correlated to the Na.sub.2 CO.sub.3 /WO.sub.3 weight ratio such as to effect the selective dissolution of at least about 95% of the WO.sub.3 in the concentrate and provide a pregnant liquor containing WO.sub.3 while inhibiting substantial dissolution of gangue minerals.

Abstract: A method for producing tungsten compounds low in phophorus. Calcium tungstate is precipitated from a tungstate solution possibly containing phosphate with a calcium compound. The resulting precipitate is reacted with an alkali carbonate solution under pressure of preferably 15 to 25 bar and the solution resulting is separated from the residue containing substantially all of the phosphate. The resulting solution is collected and is suitable for production of tungsten compositions low in phosphorus.

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: Oxide ores or ore concentrates containing organic matter are slurried with water and heated to a temperature of at least about 230.degree. C. under an oxygen partial pressure of at least about 25 psi to oxidize the organic matter. Advantageously, the process in accordance with the present invention can be used in the treatment of tungsten concentrates and can be employed while the tungsten concentrates are being digested with sodium carbonate or sodium hydroxide solutions.

Abstract: A process for preparing W, Mo or mixed metal oxides thereof by oxidizing a reduced metal oxide of the formula (NH.sub.m R.sub.4-m).sub.q.sup.+ MO.sub.p where each R is independently C.sub.1 -C.sub.20 aliphatic, C.sub.7 -C.sub.14 araliphatic or C.sub.3 -C.sub.8 cycloaliphatic with the proviso that adjacent R's, together with the nitrogen atom to which they are attached, may form a 5, 6 or 7 membered heterocyclic ring, m is an integer from 0 to 4, q is a number from about 0.001 to 1/3, M is W or Mo and p is a number from 2 to 3 with aqueous hydrogen peroxide. The so-treated reduced metal oxide is isolated and heated in an oxygen containing atmosphere to form metal oxides of the formula MO.sub.p.

Abstract: A process for conditioning a tungsten concentrate containing tungsten as WO.sub.3, sulfur as sulfide, and calcite to fix at least a portion of the sulfur as calcium sulfate by reaction with the calcite, comprises providing a tungsten concentrate having a calcite content such that less than about 15 wt. % calcium sulfate based on the weight of the WO.sub.3 in the concentrate will be formed and heating the concentrate to a temperature of at least about 500.degree. C. in an oxidizing atmosphere to oxidize substantially all the sulfur in the concentrate to provide a conditioned concentrate having a calcium sulfate content less than about 15% based on the weight of the WO.sub.3, whereby the conditioned concentrate can be efficiently leached with alkali metal carbonates or hydroxides and the resulting alkali metal tungstate solution can be effectively treated to recover an ammonium tungstate solution.

Abstract: A process for the soda digestion of mixed wolframite and scheelite concentrates is provided, the process comprising forming a slurry of the mixed wolframite and scheelite concentrates in an aqueous sodium carbonate solution and then digesting the slurry in an autoclave at a temperature of at least about 180.degree. C. During digestion a predetermined amount of sodium hydroxide is added calculated stoichiometrically to react with NaHCO.sub.3 formed as a result of the hydrolysis of FeCO.sub.3 or FeCO.sub.3 and MnCO.sub.3 produced during the digestion of the wolframite and convert it to Na.sub.2 CO.sub.3. The concentration of the Na.sub.2 CO.sub.3 solution is substantially inversely correlated to the digestion temperature and substantially directly correlated to the Na.sub.2 CO.sub.3 /WO.sub.3 weight ratio ranging from about 0.9 to 2 such as to effect dissolution of at least about 95% of the WO.sub.3 in the concentrate and provide a pregnant liquor containing said WO.sub.3.

Abstract: A process for the soda ash digestion of refractory tungsten concentrates is provided, the process comprising forming a slurry of the concentrate in an aqueous solution to which sodium carbonate is added in stages while digesting the slurry in an autoclave at a selected elevated temperature of at least about 180.degree. C. to control the concentration of the sodium carbonate during digestion to provide high extraction yields of the contained WO.sub.3. The total amount of the Na.sub.2 CO.sub.3 added stage-wise to complete the digestion is substantially inversely correlated to the digestion temperature and substantially directly correlated to the Na.sub.2 CO.sub.3 /WO.sub.3 weight ratio such as to effect dissolution of at least about 97%, and generally at least about 98%, of the WO.sub.3 in the concentrate and provide a pregnant liquor containing WO.sub.3, the stage-wise addition of the sodium carbonate being such as to inhibit the dissolution of gangue minerals, such as silica, contained in the concentrate.

Abstract: Alloy scrap containing refractory metals such as chromium, molybdenum, tungsten, vanadium, niobium and tantalum and base metals such as nickel, cobalt, copper and iron are treated to partition the refractory metal values from the base metal values without an energy intensive remelting step. The scrap in finely divided form is calcined in the presence of an oxygen containing gas and a member of a certain group of alkali metal salts at a temperature in the range of 800.degree. C. to 1150.degree. C. for 1/4 hour to four hours. This treatment converts the refractory metals to alkali metal molybdates, tungstates, chromates, vanadates, niobates and tantalates and the base metals to oxides. The calcined product may then be water leached to produce a substantially base metal-free liquor rich in refractory metal values. Both the refractory and the base metal values may be subsequently recovered by conventional hydrometallurgical techniques.

Abstract: A calcium tungstate concentrate is produced by slurrying an aqueous sodium tungstate liquor with calcium carbonate at about 130.degree. C. to about 200.degree. C. while providing sufficient carbon dioxide overpressure to convert sodium carbonate in the slurry to sodium bicarbonate, wherein the conversion of sodium tungstate to solid calcium tungstate in the slurry is promoted. The carbon dioxide is then stripped from the slurry, causing the sodium bicarbonate to convert to sodium carbonate, and a calcium tungstate concentrate is filtered from the slurry. The invention is useful in upgrading impure calcium tungstate concentrates.

Abstract: For rapid and efficient recovery of dissolved molybdenum from spent acid, the spent acid solution is first diluted to a predetermined acid-water volume ratio and anhydrous ammonia added thereto to raise the solution temperature to at least about 90.degree. C. The solution temperature is maintained at less than boiling and the ammonia addition continued until the solution pH is from about 1.5 to about 3.5. The partially neutralized solution is then seeded with solid ammonium molybdate particles in order to hasten the onset of nucleation. The seeded solution is maintained at a temperature of at least about 90.degree. C. but less than the boiling temperature for a period of from about one hour to about four hours in order to precipitate substantially all molybdenum therefrom as ammonium molybdate. Thereafter, the precipitated ammonium molybdate is separated from the residual solution.

Abstract: Disclosed is a process for recovering chromium, vanadium, molybdenum, and tungsten from secondary resources such as alloy scrap comprising a refractory metal and base metals such as cobalt nickel, iron, and copper. The scrap is calcined with sodium carbonate in air to convert the refractory metal values to MoO.sub.4.sup..dbd., VO.sub.4.sup..tbd., WO.sub.4.sup..dbd., CrO.sub.4.sup..dbd., and the base metals to water insoluble oxides. A leach of the calcined materials produces a pregnant liquor rich in refractory metals which, after separation of the vanadium, molybdenum and tungsten values, is treated with CO, CHOO.sup.-, CH.sub.3 OH, or HCHO to reduce Cr.sup.+6 to Cr.sup.+3. The carbonate and bicarbonate salts produced as a byproduct of the reduction are recycled to the calcination stage.As a result of the V, W, and Mo partition, a mixed solid comprising CaO.multidot.nV.sub.2 O.sub.5, CaMoO.sub.4, and CaWO.sub.4 is produced.

Abstract: Dissolved molybdenum is removed from sodium tungstate solutions by adding sulfuric acid to lower the pH value of the solution to between about 8 and about 5, adding to the sodium tungstate solution a water-soluble sulfide in an amount of at least 0.5 gram per liter (gpl) in excess of that required to precipitate as sulfides molybdenum and certain other metals, then lowering the pH value of the sodium tungstate solution to between about 4.0 and about 1.5 as rapidly as possible with sulfuric acid in such a way as to precipitate molybdenum trisulfide while minimizing co-precipitation of tungsten.

Abstract: A process is disclosed for recovering tungsten and molybdenum values from tungsten concentrates containing molybdenum in an amount at least about one-twentieth of the amount of contained WO.sub.3. The concentrate, generally a wolframite concentrate, is subjected to dissolution in hot NaOH solution to provide a pregnant liquor or solution containing tungsten and molybdenum values. The solution, after purification, is treated with a sulfide precipitation agent to precipitate MoS.sub.3 and some WS.sub.3 using a stoichiometric excess of a sulfide precipitating agent to produce a filtrate containing tungsten substantially free of molybdenum. The sulfide precipitate is dissolved in dilute NaOH solution and again precipitated using a stoichiometric deficient amount of the sulfide precipitating agent to produce a precipitate of MoS.sub.3 low in tungsten. The foregoing sulfide precipitation steps may be reversed.

Abstract: Apparatus for the thermal treatment of finely divided material for the calcination of cement wherein the material is preheated in a multi-stage heat exchanger and later passed to a calcining furnace. The material is partly deacidified in a pre-calcination zone before entering the sintering furnace where further calcining and sintering of the material is completed. A portion of the feed material is treated with rapidly oxidizing fuel components in a pre-calcination zone in a first stage and with more slowly oxidizing fuel components in a second stage, the more slowly oxidizing fuel components being a mixture of relatively fine granulated fuel particles of substantially uniform size and larger particles of briquetted or coarsely broken fuel.

Abstract: Disclosed is a process for recovering chromium, vanadium, molybdenum, and tungsten from secondary resources such as alloy scrap comprising a refractory metal and base metals such as cobalt, nickel, iron, and copper. The scrap is calcined with sodium carbonate in air to convert the refractory metal values to MoO.sub.4.sup.=, VO.sub.4.sup..ident., WO.sub.4.sup.=, and CrO.sub.4.sup.= and the base metals to water insoluble oxides. A leach of the calcined materials produces a pregnant liquor rich in refractory metals which, after separation of the vanadium, molybdenum and tungsten values, is treated with CO, CHOO.sup.-, CH.sub.3 OH, or HCHO to reduce Cr.sup.+6 to Cr.sup.+3. The carbonate and bicarbonate salts produced as a byproduct of the reduction are recycled to the calcination stage.As a result of the V, W, and Mo partition, a mixed solid comprising CaO.nV.sub.2 O.sub.5, CaMoO.sub.4, and CaWO.sub.4 is produced.

Abstract: Disclosed is a process for recovering chromium, vanadium, molybdenum, and tungsten from secondary resources such as alloy scrap comprising a refractory metal and base metals such as cobalt, nickel, iron, and copper. The scrap is calcined with sodium carbonate in air to convert the refractory metal values to MoO.sub.4.sup.=, VO.sub.4.sup..ident., WO.sub.4.sup.=, and CrO.sub.4.sup.= and the base metals to water insoluble oxides. A leach of the calcined materials produces a pregnant liquor rich in refractory metals which, after separation of the vanadium, molybdenum and tungsten values, is treated with CO, CHOO.sup.- CH.sub.3 OH, or HCHO to reduce Cr.sup.+6 to CR.sup.+3. The carbonate and bicarbonate salts produced as a byproduct of the reduction are recycled to the calcination stage.As a result of the V, W, and Mo partition, a mixed solid comprising CaO.nV.sub.2 O.sub.5, CaMoO.sub.4, and CaWO.sub.4 is produced.

Abstract: Disclosed is a process for recovering chromium, vanadium, molybdenum, and tungsten from secondary resources such as alloy scrap comprising a refractory metal and base metals such as cobalt, nickel, iron, and copper. The scrap is calcined with sodium carbonate in air to convert the refractory metal values to MoO.sub.4.sup..dbd., VO.sub.4.sup..tbd., WO.sub.4.sup..dbd., and CrO.sub.4.sup..dbd. and the base metals to water insoluble oxides. A leach of the calcined materials produces a pregnant liquor rich in refractory metals which, after separation of the vanadium, molybdenum and tungsten values, is treated with CO, CHOO.sup.-, CH.sub.3 OH, or HCHO to reduce Cr.sup.+6 to Cr.sup.+3. The carbonate and bicarbonate salts produced as a byproduct of the reduction are recycled to the calcination stage.As a result of the V, W, and Mo partition, a mixed solid comprising CaO.nV.sub.2 O.sub.5, CaMoO.sub.4, and CaWO.sub.4 is produced.

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: 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: Molybdenum or other heavy metal anions and ferric sulfate are reclaimed from wastewater skimmings, that result from treatment of wastewaters through formation of insoluble heavy metal ferric salts and flotation, by treating the skimmings with aqueous caustic at 150.degree.-225.degree. F. to form a solution of the heavy metal anions and a residual solids fraction, separating the solids and contacting the residual solids with sulfuric acid to produce ferric sulfate.

Abstract: A process for removal of heavy metals in their anionic state, particularly tungsten and molybdenum, from industrial mining wastewater by chemical precipitation of the heavy metal values, followed by gas flotation.

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: Process is provided for removal of alumina from aqueous alkali metal chromate solutions containing the same, which comprises contacting the aqueous solution with a soluble-silica compound under conditions sufficient to effect reaction of alumina with silica for formation of crystalline alkali metal alumino silicate, and removing the crystalline alkali metal alumino silicate from the reaction mixture.

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.