Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Group vib metal
Patent
1989-02-16
1990-06-12
Stoll, Robert L.
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Group vib metal
423 53, C01G 3900
Patent
active
049331523
ABSTRACT:
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.
REFERENCES:
patent: 4525331 (1985-06-01), Cheresnowsky et al.
patent: 4612172 (1986-09-01), Brunelli et al.
patent: 4643884 (1987-02-01), Cheresnowsky et al.
Christini James N.
Scheftic Judy L.
Castle Donald R.
GTE Products Corporation
Langel Wayne A.
Quatrini L. Rita
Stoll Robert L.
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