Gte Products Corporation

Judy L Scheftic

Michael J Cheresnowsky

James N Christini

Robert G Mendenhall

Michael J Chereslowsky

A method is disclosed for producing fine size molybdenum trioxide powder which involves heating ammonium dimolybdate in ambient atmosphere at a temperature of from about 455.degree. C. to about 465.degree. C. for a time of from about 5 hours to about 6 hours to produce a first molybdenum trioxide which is granulated to about -10 mesh and then heated in a furnace in which there are three heating zones. The first molybdenum trioxide is heated in the first heating zone at a temperature of from about 550.degree. C. to about 590.degree. C., in the second heating zone at a temperature of from about 580.degree. C. to about 610.degree. C. and thereafter in the third heating zone at a temperature of from about 580.degree. C. to about 625.degree. C., with the feed rate of material in the three zones being from about 1.5 to about 3.0 kg/hr to produce a yellow molybdenum trioxide. The yellow molybdenum trioxide is then cooled and granulated to about -40 mesh. The molybdenum trioxide thus produced has a particle size of from about 2.0 to about 10.0 micrometers in diameter and a surface area of from about 0.1 to about 1.5 M.sup.2 /g.

Method for producing fine size yellow molybdenum trioxide powder

A process is disclosed for purifying molybdenum containing arsenic and phosphorus which involves leaching molybdenum trioxide in an acid at a temperature of above about 70.degree. C. to remove impurities from the molybdenum trioxide and produce a partially purified molybdenum trioxide, adding to an acidic slurry of the leached molybdenum trioxide, a source of magnesium ions in a solid form with the amount of magnesium and the magnesium ion concentration in the subsequently formed ammonium molybdate solution being sufficient to subsequently form insoluble material containing greater than about 80% by weight of the arsenic and greater than about 80% by weight of the phosphorus, and ammonia in an amount sufficient to subsequently dissolve the molybdenum and subsequently form the insoluble material, digesting the resulting ammoniated slurry at a temperature sufficient to dissolve the molybdenum and form an ammonium molybdate solution while the pH is maintained at from about 9 to about 10 to form the insoluble material wherein the arsenic is present as magnesium ammonium arsenate and the phosphorus is present as magnesium ammonium phosphate, and separating the insoluble material from the ammonium molybdate solution.

Process for purifying molybdenum

A process for purifying molybdenum, which comprises first leaching impure molybdenum trioxide containing potassium in a liquid medium of nitric acid, and an ammoniacal liquor, wherein the nitric acid concentration is about 3.5 to 4.0 moles per liter and the ammonium nitrate concentration is about 0.5 to 1.0 moles per liter, at greater than 50.degree. C. to solubilize the major portion of the potassium and produce a once-leached molybdenum trioxide and a first liquor, removing the once-leached molybdenum oxide from the first liquor, re-leaching the once-leached molybdenum trioxide in nitric acid having a concentration of about 3.5 to 4.0 moles per liter, at greater than 50.degree. C. to produce a twice-leached molybdenum trioxide and a second liquor, removing the twice-leached molybdenum oxide from the second liquor, water washing the twice-leached molybdenum trioxide, digesting the molybdenum trioxide in ammonium hydroxide at greater than 50.degree. C. at a pH of greater than 9.0 to form an ammonium molybdate solution, crystallizing ammonium dimolybdate from the ammonium molybdate solution, separating the ammonium dimolybdate crystals from the spent mother liquor which contains the balance of the starting molybdenum, combining a sufficient amount of spent mother liquor with a sufficient amount of the second liquor to provide the ammonium ion required to maintain the concentration of ammonium nitrate and nitric acid in the liquid medium, and using the combined liquors as the liquid medium in the first leaching step.

Continuous process for purifying molybdenum

A method is disclosed for purifying ammonium dimolybdate which comprises dissolving ammonium dimolybdate containing arsenic as an impurity in water to form an ammonium molybdate solution and insolubles containing essentially all of the arsenic, filtering off the insolubles from the solution, adjusting the pH of the solution to at least about 9.0 and then crystallizing pure ammonium dimolybdate from the solution wherein the arsenic content is less than about 8 weight ppm.

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South Waverly, PA, United States of America

Judy L Scheftic