Chemistry of inorganic compounds – Oxygen or compound thereof – Metal containing
Patent
1985-02-25
1986-09-16
Doll, John
Chemistry of inorganic compounds
Oxygen or compound thereof
Metal containing
C01G 4100
Patent
active
046121838
ABSTRACT:
A method is disclosed for producing crystalline ammonium metatungstate from ammonium paratungstate. The method involves heating ammonium paratungstate in a multiple hearth furnace at from about 200.degree. C. to about 400.degree. C. to form a relatively uniformly heated ammonium paratungstate. A slurry of the heated ammonium paratungstate in water is then digested at from about 70.degree. C. to about 100.degree. C. for less than about 6 hours at relatively constant volume while maintaining the pH of the slurry at from about 4.2 to about 3.0 by the addition of ammonia as necessary to form a solution of ammonium metatungstate. The resulting ammonium metatungstate solution is then evaporated to a fraction of its original volume to concentrate it and any insolubles are removed. The ammonium metatungstate is then crystallized from the concentrated solution.
REFERENCES:
patent: 3175881 (1965-03-01), Chiola et al.
patent: 3956474 (1976-05-01), Ritsko
patent: 4504461 (1985-03-01), Carpenter et al.
Boyer Carl W.
Ennis Donald H.
Kim Tai K.
MacInnis Martin B.
Castle Donald R.
Doll John
GTE Products Corporation
Langel Wayne A.
Quatrini L. Rita
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