Gte Products Corporation

Gte Sylvania Incorporated

Osram Sylvania Inc.

Gte Service Corporation

Clarence D Vanderpool

Martin B MacInnis

Richard A Scheithauer

Michael J Miller

Richard G Gingerich

Judith A Ladd

Tai K Kim

Robert P McClintic

Joseph E Ritsko

Michael J Cheresnowsky

Richard G W Gingerich

James C Patton, Jr

Mary A Fedorchak

James N Christini

Howard L Acla

Alan D Douglas

Thomas A Wolfe

Martin C Vogt

Brice E Martin

John A Powers

Geoffrey L Harris

Eric F Husted

William Scheithauer, Jr

Timothy J Hoffman

Jia-Ming Chern

Richard G Warmington

Martin B McInnis

A method of increasing the color-stability of an electroluminescent phosphor which comprises the steps of forming the phosphor and then firing the formed phosphor in a vacuum in the presence of a material selected from the group of Eu, Ce, and Sm for a time sufficient to provide said increase in color-stability.

Stabilization of color in heated electroluminescent phosphor

An electroluminescent phosphor with an extended half-life is created by means of the present invention by taking an amount of a phosphor and treating it with antimony comprising the steps of placing an amount of antimony in an inert reaction vessel, placing a vapor permeable filter on top of the antimony, placing a phosphor with a given half-life on top of the vapor permeable filter, evacuating the reaction vessel below one atmosphere and heating it for a period of time to allow the antimony to react with the phosphor to produce a new phosphor with an extended half-life.

Process for producing electroluminescent phosphor with extended half-life

An electroluminescent phosphor containing an effective amount of bismuth to increase the half-life of the phosphor compared to the half-life of the phosphor without the bismuth. The phosphor is produced by the method comprising the steps of preparing the electroluminescent phosphor; adding granular, elemental bismuth to the bottom of a quartz reaction vessel; covering the bismuth with a layer of quartz wool; placing the phosphor on top of the quartz wool; evacuating the reaction vessel to about 750-760 mm Hg and sealing the vessel; and heating the vessel to between about 500 to 700.degree. C. for about 24 to 72 hours.

Electroluminescent phosphor with extended life and method of making same

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 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 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

A method is disclosed for producing ammonium paratungstate from cemented tungsten carbide which comprises subjecting the cemented tungsten carbide to electrolysis by passing about 0.5 to about 20 volts through an ammoniacal solution selected from the group consisting of ammonium hydroxide-ammonium chloride solution, ammonium hydroxide-ammonium carbonate solution, and ammonium hydroxide-ammonium sulfate solution, wherein platinum and the cemented tungsten carbide serve as the anode and wherein the anode is immersed in the solution, to decompose the cemented tungsten carbide and form a solution of ammonium tungstate from which is crystallized ammonium paratungstate.

Electrolytic method for producing ammonium paratungstate from cemented

A method is disclosed for removing iron from iron-contaminated sulfuric acid to render the sulfuric acid suitable for ion membrane processing which comprises contacting the iron-contaminated sulfuric acid with an oxidizing agent to oxidize essentially all of the iron to the +3 oxidation state, contacting the resulting iron-contaminated sulfuric acid containing oxidized iron with a complexing agent which can be citric acid, oxalic acid, and tartaric acid, with the amount of the complexing agent being sufficient to complex essentially all of the oxidized iron, and contacting the resulting iron-contaminated sulfuric acid containing the complexed iron with activated carbon to remove essentially all of the iron and produce a purified sulfuric acid solution.

Method for purifying sulfuric acid solutions

A method is disclosed for removing organic and tungsten from sodium sulfate solutions to render the solutions suitable for ion membrane processing, which comprises contacting the solution wherein the pH of the solution is no greater than about 7, with activated carbon to remove essentially all of the organic and the tungsten therefrom and form a purified sodium sulfate solution.

Method for removing organic and tungsten from sodium sulfate solution

Methods are disclosed for recovering one or more of the metals of tungsten and molybdenum from metal-cellulose material. One method involves digesting the material in a mineral acid selected from the group consisting of hydrochloric acid having a concentration of at least about 4 normal, and sulfuric acid having a concentration of at least about 9 normal at a temperature of at least about 50.degree. C. for a sufficient time to form a digestion solid containing the major portion of the tungsten and a digestion solution containing a portion of any molybdenum which is present in the material, and separating the solid from the solution. Another method involves having as the starting material a metal-cellulose material comprising one or more of the metals of tungsten and molybdenum and elements selected from the group consisting of arsenic, phosphorus, silicon, and combinations thereof. The digestion is carried out as described above to form a digestion solution containing the major portion of any tungsten and molybdenum which is present, and a residue, followed by separating the digestion solution from the residue.

Recovery of tungsten and molybdenum

A method for converting cobalt to cobalt powder is disclosed which comprises heating a starting mixture of cobalt and zinc in a non-reacting atomosphere at a first temperature of below the boiling point of zinc up to about 900.degree. C. in a non-reacting atmosphere for a length of time sufficient to cause the alloying of a portion of the zinc and cobalt, with the weight ratio of zinc to cobalt being less than about 10. The temperature of the resulting partially alloyed mixture is slowly raised to a second temperature of from about 900.degree. C. to about 960.degree. and is maintained for a time sufficient only to form a reaction product in which essentially all of the cobalt is alloyed with zinc and to keep the evaporation of zinc to a minimum. The reaction product is then heated at a pressure below atmospheric pressure at a third temperature of no greater than about 950.degree. C. for a time sufficient to evaporate essentially all of the zinc and produce a cobalt ingot which is pulverizable when cooled to room temperature.

Method for converting cobalt to cobalt metal powder

A process is disclosed for recovering tungsten, iron, and manganese from tungsten bearing material. The process involves digesting the material in a sufficient amount of sulfuric acid at a temperature of at least about 80.degree. C. for a sufficient time in the presence of coal as a reducing agent to form a digestion solution containing the major portion of the scandium, iron, and manganese and a digestion residue containing the major portion of the tungsten, followed by separating the solution from the residue. The major portion of the scandium can be extracted from the digestion solution with an organic solution consisting essentially of a mixture of tertiary alkyl primary amines which are present in an amount sufficient to extract the major portion of the scandium, and the balance an essentially aromatic solvent. The scandium is stripped from the organic with hydrochloric acid which is then separated from the stripped organic. The extraction can be accomplished by an organic solution consisting essentially of an extracting agent which is a dialkyl phosphoric acid and an essentially aromatic solvent. In this latter case, the stripping agent for the scandium is an aqueous solution of ammonium carbonate.

Recovery of tungsten, scandium, iron, and manganese from tungsten

A method is disclosed for recovering cobalt, which comprises adding ammonia to a cobalt chloride solution to a pH of from about 8.8 to about 9.6 with oxidation, to form hexammine cobalt (III) chloride, adding to the resulting solution of hexammine cobalt (III) chloride, sodium chloride in an amount sufficient to result in the precipitation of at least about 98% by weight of the cobalt as cobalt hexammine (III) chloride at a temperature of no greater than about 40.degree. C., separating the precipitate of cobalt hexammine (III) chloride from the resulting mother liquor which contains the balance of the cobalt, adding to the mother liquor, aluminum powder in an amount sufficient to result in the precipitation of the balance of the cobalt as cobalt metal, and separating the cobalt metal from the resulting spent liquor.

Method for recovering cobalt from hexammine cobaltic (111) solutions

A process is disclosed for recovering tungsten from tungsten bearing material containing arsenic. The process involves adjusting a water slurry of the material to a pH of less than about 4 with an acid to solubilize the major portion of the tungsten, adding an insoluble ferric compound to the slurry to form a two phase system in which the solid phase contains the major portion of the arsenic and of any phosphorus which may be present, and a solution phase containing the major portion of the tungsten. After separation of the solid from the solution, the solution is adjusted to a pH of less than about 2 with an acid and a suffficient amount of hexamethylenetetramine is added to the solution to precipitate the major portion of the tungsten, followed by separating the precipitate from the resulting liquor. The solid phase containing the arsenic and phosphorus, if any, can be contacted with water and a soluble ferric salt to produce a treated solid which passes the EP toxicity test.

Process for recovering tungsten from tungsten bearing material

A process is disclosed for recovering scandium from a tungsten bearing material containing tungsten, iron manganese and scandium. The process involves digesting the material in an aqueous solution selected from the group consisting of a saturated solution of sulfur dioxide and a sulfuric acid solution containing an additional reducing agent at a sufficient temperature for a sufficient time to form a digestion solution containing the major portion of the scandium, iron, and manganese, and a digestion solid containing the major portion of the tungsten which is separated from the digestion solution. The major portion of the scandium is extracted from the digestion solution with an organic consisting essentially of an extracting agent which is essentially a mixture of alkyl primary amines which are present in an amount sufficient to extract the major portion of the scandium without extracting appreciable amounts of iron and manganese, and the balance an essentially aromatic solvent. After separation of the scandium containing organic from the raffinate, the organic is stripped of the scandium with hydrochloric acid which is then separated from the stripped organic. In an optional additional steps, iron is recovered by adjusting the pH of the raffinate to precipitate the major portion of the iron and manganese which is separated from the resulting liquor. A sufficient amount of chlorine gas is contacted with an aqueous slurry of the precipitate at a sufficient temperature for a sufficient time to form a manganese containing solution containing the major portion of the manganese which was in the precipitate and a solid containing the major portion of the iron which was in the precipitate.

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Towanda, PA, United States of America

Clarence D Vanderpool