Process to recover metals from spent catalyst

A process to reclaim metals from catalysts comprising alumina-containing carriers and metals, said catalysts containing oil, said process comprising:

• a) collecting one or more catalysts, said catalysts containing two or more metals as metal sulfides wherein at least two of said metal sulfides are selected from the group consisting of molybdenum sulfides and vanadium sulfides, and tungsten sulfides and vanadium sulfides;
• b) deoiling said catalysts;
• c) leaching said deoiled catalysts in the presence of caustic and oxygen at atmospheric pressure, a temperature less than 60° C., and a pH range of about 10-13 for a time sufficient to convert in a range from about 50-70% of said metal sulfides to soluble metal and sulfur species, thereby forming a first leached slurry comprising a first liquid stream containing soluble metal and sulfur species and a first solid;
• d) separating said first leached slurry into said first liquid stream and said first solid,
• e) leaching said first solid in the presence of caustic and oxygen at an oxygen partial pressure greater than 10 psia, a temperature greater than about 70° C., and a pH greater than about 10 for a time sufficient to convert greater than about 90% of the metal sulfides to soluble metal and sulfur species based upon the metal sulfides present on the catalysts catalyst before step (c), thereby forming a second leached slurry comprising a second liquid stream containing soluble metal and sulfur species and a second solid;
• f) separating the second leached slurry into said second liquid stream and said second solid;
• g) collecting said first liquid stream and said second liquid stream to form a combined liquid stream;
• h) oxidizing said combined liquid stream in the presence of oxygen or air or both, thereby forming an oxidized liquid stream;
• i) cooling said oxidized liquid stream and adjusting a pH of the oxidized liquid stream to about 6.5, thereby precipitating dissolved alumina, and separating said alumina from said oxidized liquid stream;
• j) adjusting the pH of the oxidized liquid stream to a pH of about 2.5;
• k) contacting the oxidized liquid stream with an organic solvent containing an extractant effective to transfer the soluble metal species into the organic solvent, thereby creating an organic phase containing at least one soluble metal species and a substantially metals-free aqueous liquid containing sulfate;
• l) recovering said substantially metals-free aqueous liquid containing sulfate;
• m) stripping the soluble metal species from the organic phase in the presence of an aqueous ammonia solution, thereby forming an aqueous phase containing metal species;
• n) adjusting the pH of the aqueous phase to selectively precipitate at least one metal as at least one ammonium metal salt;
• and
• o) separating said at least one ammonium metal salt from said aqueous phase and recovering said at least one ammonium metal salt.