Gte Products Corporation

Osram Sylvania Inc.

Michael J Miller

Clarence D Vanderpool

Richard A Scheithauer

Martin B MacInnis

Thomas A Wolfe

James N Christini

Martin C Vogt

Raj P Singh

Richard G Gingerich

Michael J Cheresnowsky

Eric F Husted

Judith A Ladd

Tai K Kim

Thomas J Patrician

Shellie K Northrop

Robert G Mendenhall

Richard R Borchardt

Shirley S Schaeffer

Claraence D Vanderpool

Jia-Ming Chern

Vernon L Carr, Jr

David T Smith

A direct dissolution method for the purification of technical grade hydrated ammonium tantalum oxide (HATO), (NH ) H Ta O .nH O), and related compounds such as tantalum hydroxide and tantalum oxide is described. The method preferably uses ammonium bifluoride as fluoride source in place of the hydrofluoric acid used in the conventional methods. Other fluoride compounds such as NaF, KF, and CaF may be used.

Method for purifying a tantalum compound using a fluoride compound and sulfuric acid

A method for purifying a phosphorus containing scheelite ore is described wherein the calcite phase is selectively dissolved prior to dissolution of the apatite phase. Selective dissolution of the calcite produces several benefits: (1) a usable calcium solution, (2) enhanced apatite dissolution, and (3) lower volumes of toxic acid solution for disposal.

Purification of phosphorus containing scheelite ore

Highly pure tantalum compounds are made by slurrying hydrated ammonium tantalum oxide or tantalum hydroxide with concentrated sulfuric acid followed by dissolution with concentrated hydrofluoric acid. After diluting the concentrated acidic solution with water, a soluble potassium compound is added to precipitate a highly pure potassium fluorotantalate. Further steps are used to convert the highly pure potassium fluorotantalate into a highly pure tantalum oxide.

Method for making a highly pure tantalum compound

A method for recovering tungsten from a tungsten containing spent catalyst comprises digesting the catalyst in aqueous sodium hydroxide solution wherein the mole ratio of the sodium hydroxide to the tungsten contained in the spent catalyst is from about 2.6 to about 4.2 and wherein the amount of water is sufficient to dissolve the subsequently produced sodium tungstate, at a temperature of at least about 90.degree. C. for a length of time of at least about 1 hour to convert greater than about 77% by weight of the tungsten contained in the spent catalyst to sodium tungstate and form a sodium tungstate solution thereof and a residue containing the balance of the starting tungsten, and separating the sodium tungstate solution from the residue. Essentially all of the tungsten is recovered as sodium tungstate by first grinding the catalyst prior to the digestion and by using a mole ratio of sodium hydroxide to tungsten of about 3.8 to 4.2.

Method for recovery of tungsten from spent catalysts

A simple, cost effective method for reclaiming tungsten values from tungsten-thoria has been invented. The method involves reacting the tungsten-thoria with molten sodium hydroxide to form a soluble sodium tungstate and an insoluble residue of thoria, cooling the melt, dissolving the melt in water, and filtering to separate the insoluble residue of thoria from the dissolved sodium tungstate. The method resulting in substantially all of the tungsten values being reclaimed as sodium tungstate and acutely reducing the amount of radioactive material for disposal.

Reclamation of tungsten values from tungsten-thoria

A method is provided whereby tungsten values are recovered from ferrotungsten by completely oxidizing the ferrotungsten at high temperatures in an oxygen atmosphere followed by digestion with sodium hydroxide to form soluble sodium tungstate. The sodium tungstate is then purified by conventional means. The method may be used to recover at least about 90% of the tungsten values present in the ferrotungsten.

Recovery of tungsten from ferrotungsten

A process for producing potassium and silicon doped molybdenum (KS molybdenum). The process involves mixing an aqueous ammonium molybdate solution and a dilute aqueous potassium silicate solution. The molybdate solution has a pH and a specific gravity sufficient to promote formation of diammonium molybdate crystals in the mixture. Preferably, the pH is about 8.8-11.0 and the specific gravity is about 1.20-1.32. The amount of potassium silicate and the amount of potassium silicate solution are selected to provide predetermined amounts of potassium and silicon in the mixture, preferably about 800-1300 ppm potassium and about 500-1100 ppm silicon, both amounts based on the amount of molybdenum. The mixture is heated to aid dissolution of the potassium silicate and ammonium molybdate in said mixture and to produce a homogeneous solution of ammonium molybdate, potassium, and silicon. The ammonium dimolybdate doped with potassium and silicon is then crystallized out of solution and calcined, for example in an atmosphere of dissociated ammonia, to produce molybdenum dioxide doped with potassium and silicon. The doped molybdenum dioxide is reduced, for example in a flowing hydrogen atmosphere, to produce a doped molybdenum powder, which then may be pressed and sintered to full density.

Process for producing KS molybdenum

A method is disclosed for the dissolution and purification of tantalum pentoxide. The impure tantalum pentoxide is reacted with a potassium-containing compound to form potassium tantalate. The potassium tantalate is optionally slurried with sulfuric acid and dissolved in an HF medium. The solution is suitable for purification by conventional ion exchange or solvent extraction methods. A potassium fluorotantalate precipitate may also be formed by adding KCl to the solution. The fluorotantalate precipitate may be further processed into a pure tantalum pentoxide by suspending the precipitate in an aqueous solution optionally containing a chelating agent and adding ammonium hydroxide to form ammonium tantalum oxide which can then be converted to tantalum pentoxide by calcining at high temperature.

Method for the dissolution and purification of tantalum pentoxide

A process for recovering tungsten as an ammoniacal tungstate which comprises reacting a tungsten containing material with sodium hydroxide to produce sodium tungstate and forming a first aqueous sodium tungstate solution therefrom, crystallizing sodium tungstate from the first aqueous sodium tungstate solution, dissolving the resulting sodium tungstate crystals in an aqueous medium to form a second aqueous sodium tungstate solution, extracting tungsten from the second aqueous sodium tungstate solution with an organic extracting agent wherein the extracting agent containing tungsten is capable of being stripped of the extracted tungsten by ammonia, and thereafter stripping the extracted tungsten from the organic extracting agent with ammonia to form an ammoniacal tungstate solution, crystallizing a portion of the tungsten contained in the ammoniacal tungstate solution to form a two phase system wherein an ammoniacal tungstate compound comprises the first phase and wherein the resulting mother liquor containing the balance of the contained tungsten comprises the second phase, and repeating the process using the mother liquor as at least a portion of the aqueous medium to dissolve the sodium tungstate crystals.

Process for recovering tungsten as an ammoniacal tungstate compound in

Aluminum is removed from ammonium molybdate solution by the use of Mg.sup.+2 in the solution to precipitate out the aluminum.

Removal of aluminum from ammonium molybdate solution

In a process for reducing the dust content of cobalt metal powder, the starting cobalt powder containing dust is milled for a sufficient period of time to increase the bulk density and decrease the dust content while substantially maintaining the original Fisher Sub Sieve Size.

Method to reduce the dustiness of extrafine cobalt powder

A method is disclosed for recovering oxalate from oxalate containing solutions containing complexes of iron and chromium. The method involves adjusting the pH of the solution to from about 1 to 2, adding calcium chloride in an amount equal to at least about 3 moles per mole of iron, and digesting the resulting calcium chloride treated solution at at least about 50.degree. C. for a sufficient time to form a solid consisting esssentially of calcium oxalate, followed by separating the solid from the resulting mother liquor.

Recovery of oxalate from solutions containing complexes of iron and

A method of making extrafine pure elemental metal powder from a highly malleable pure elemental metal powder. The pure elemental metal powder is oxidized, ground to a desired average particle size, reduced in a reducing atmosphere to a pure elemental metal powder, and then sieved to obtain the desired fraction of extrafine pure elemental metal powder.

Method for producing extrafine pure metal powder

In the manufacture of ammonium paratungstate, sulfide is added to a tungsten-containing solution in order to precipitate molybdenum sulfide. Volatiles, including sulfides, evolved during this process are collected in a caustic scrubbing solution. The sulfide values in the caustic scrubbing solution may be reused to precipitate molybdenum sulfide by first treating the caustic scrubbing solution with alkaline earth chloride or sulfate to precipitate out alkaline earth carbonate.

Removal of carbonate from caustic sulfide solution

A method for producing pure cobalt metal powder involves the removal of divalent cationic impurities from a trivalent hexamine cobalt chloride solution. This solution is then decomposed to an insoluble cobalt oxide-containing material, from which pure cobalt metal powder is obtained through a chemical reduction process.

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Towanda, PA, United States of America

Michael J Miller