Patent ID: 8753591

Claim:
A process for converting molybdenite to molybdenum oxide, the process comprising the steps of: A. Contacting under pressure oxygen and an aqueous suspension of molybdenite to form an acidic solution comprising dissolved molybdenum and a solid fraction comprising insoluble molybdic oxide; B. Separating the acidic solution comprising dissolved molybdenum from the solid fraction comprising the insoluble molybdic oxide; C. Converting at least a portion of the insoluble molybdic oxide of the solid fraction of step A to acid-soluble molybdic oxide; D. Combining the acidic solution comprising dissolved molybdenum of step A with the acid-soluble molybdic oxide of step C to dissolve the acid-soluble molybdic oxide; E. Extracting the dissolved molybdenum of step D into an organic solvent comprising a nonprimary amine to produce a molybdenum-rich organic phase and a molybdenum-depleted aqueous raffinate; F. Contacting the molybdenum-rich organic phase with aqueous ammonium hydroxide to recover an aqueous strip liquor comprising molybdenum as solubilized ammonium dimolybdate (ADM); G. Crystallizing at least a portion of the solubilized ADM; H. Calcining the crystallized ADM in a first calcination zone operated at 300-450° C. and with a countercurrent sweep of steam to produce a first calcined product and concentrated ammonia; and I. Calcining the first calcined product in a second calcination zone operated at a temperature 450-600° C. under and in contact with an oxygen-containing atmosphere to produce a second calcined product comprising molybdenum oxide.