Patent ID: 6180072
Filing Date: 2001-01-30
Classification: C22B,Y02P

Abstract:
A process to reclaim metals from catalysts comprising alumina-containing carriers and metals, said process comprising:a) collecting one or more catalysts, said catalysts containing one or more metals as metal sulfides wherein at least one of said metal sulfides is selected from the group consisting of molybdenum sulfides, vanadium sulfides, tungsten sulfides, and combinations thereof;b) deoiling said catalysts;c) leaching said deoiled catalysts in an atmospheric leach in the presence of air or oxygen at a pH greater than 9 for a time sufficient to convert in the range of 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 a pressure leach process in the presence of air or oxygen at a pH greater than 9 for a time sufficient to convert greater than about 90%, based upon the metal sulfides present on the catalysts before step (c), of said metal sulfides to soluble metal and sulfur species, thereby forming a second leached slurry comprising a second liquid stream containing soluble metal and sulfur species and a second solid;f) separating said 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;i) 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 a metal species containing organic phase and a substantially metals-free aqueous liquid containing sulfate;j) recovering said substantially metals-free aqueous liquid containing sulfate;k) 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;l) adjusting the pH of the aqueous phase to selectively precipitate at least one metal as at least one ammonium metal salt; andm) separating said at least one ammonium metal salt from said aqueous phase and recovering said at least one ammonium metal salt.