Appeal No. 1997-0448
Application No. 08/327,980
Vertes discloses roasting a molybdenite concentrate, pressure oxidizing roasted concentrate
which consists predominantly of molybdenum oxide, of which the majority is in the form of molybdenum
trioxide, at a temperature from about 150EC to about 350EC and a partial pressure of oxygen of at
least about 100 psi whereby suboxides of molybdenum are converted to molybdenum trioxide and
contaminating metal molybdites and sub-molybdate compounds thereof are converted to aqueous acid
soluble molybdate compounds. The resultant slurry is filtered to separate the solids, i.e.,11
predominantly molybdenum trioxide and insoluble gangue contaminants. Thereafter, the filtered solids12
are solubilized with aqueous ammonium hydroxide solution and filtered to separate or “leach out”
soluble ammonium molybdate compounds from residual solid contaminants. The resultant filtrate is13
crystallized and calcined to produce ammonium gas which is recycled back to aqueous ammonium
hydroxide, thereby yielding high purity molybdenum trioxide. Alternatively, the filtered solids can be14
solubilized with an aqueous alkali metal hydroxide solution (instead of solubilized with aqueous
ammonium hydroxide solution) to form the corresponding soluble alkali metal molybdate compound. 15
11See Vertes, col. 3, line 7 - col. 4, line 50.
12See Vertes, col. 4, lines 51-57.
13See Vertes, col. 4, line 57 - col. 5, line 3.
14See Vertes, col. 5, lines 4-24.
15See Vertes, col. 5, lines 25-30 and col. 6, lines 5-14.
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