Pressure oxidation process for the production of molybdenum trioxide from molybdenite

A process for producing molybdenum trioxide of at least technical grade from molybdenite concentrate containing molybdenite, at least one of copper in excess of 5 wt % or naturally floatable gangue minerals in excess of 10 wt %, each based on the weight of the concentrate, the process comprising the steps of:

• A. contacting an aqueous suspension of the concentrate with oxygen under a partial pressure of free oxygen of between about 75 and 200 psi and at a temperature of at least about 150 C such that at least about 95% of the molybdenite is oxidized to form a soluble hydrous molybdic oxide and insoluble molybdenum trioxide;
• B. separating the soluble molybdic oxide from the insoluble molybdenum trioxide;
• C. contacting the insoluble molybdenum trioxide with ammonium hydroxide to form soluble molybdate values;
• D. contracting the soluble molybdic oxide with an organic solvent containing an extractant that is selective for the soluble molybdic oxide such that a majority of the metal contaminants remain in the aqueous mixture while a majority of the soluble molybdic oxide is extracted into the organic solvent;
• E. removing the extracted molybdic oxide of step D from the organic solvent by contacting the organic solvent with an aqueous solution containing a stripping reagent selective for molybdenum;
• F. combining the soluble molybdate values of step C with the extracted molybdic oxide of step E to form a mixture of soluble molybdenum values;
• G. crystallizing the soluble molybdenum values of step F;
• and
• H. calcining the crystallized molybdenum values of step G to form molybdenum trioxide.

A process for producing molybdenum trioxide of at least technical grade from molybdenite concentrate containing molybdenite, at least one of copper in excess of 5 wt % or naturally floatable gangue minerals in excess of 10 wt %, each based on the weight of the concentrate, the process comprising the steps of:

• A. contacting an aqueous suspension of the concentrate with oxygen under a partial pressure of free oxygen of between about 75 and 200 psi and at a temperature of at least about 150 C such that at least about 95% of the molybdenite is oxidized to form a soluble hydrous molybdic oxide and insoluble molybdenum trioxide;
• B. separating the soluble molybdic oxide from the insoluble molybdenum trioxide;
• C. contacting the insoluble molybdenum trioxide with at least one of lime and magnesium hydroxide to form a mixture containing soluble molybdate values;
• D. combining the mixture of step C with the soluble molybdic oxide fraction of step B to form a mixture of soluble molybdenum values;
• E. contacting the aqueous mixture of step D with an organic solvent containing an extractive compound that is selective for the molybdenum values such that a majority of the metal contaminants remain in the aqueous mixture while a majority of the molybdenum values are extracted into the organic solvent;
• F. removing the extracted molybdenum values of step E from the organic solvent by contacting the organic solvent with an aqueous solution containing a stripping reagent selective for molybdenum values;
• G. crystallizing the extracted molybdenum values of step F;
• and
• H. calcining the crystallized molybdenum values of step G to form molybdenum trioxide of at least a technical grade.