Selective rejection of iron and aluminum in hydrometallurgical recovery of metals

Claim 1

IN ACID-LEACHING NON-FERROUS METAL VALUES FROM A SOLIDS MIXTURE CONTAINING (A) AT LEAST ONE DILUENT METAL SELECTED FROM THE GROUP CONSISTING OF IRON AND ALUMINUM AND (B) METAL VALUES OF AT LEAST ONE NON-FERROUS ACID AT A WHICH IS SUBSTANTIALLY INSOLUBLE IN THE LEACHING ACID AT A PH BETWEEN ABOUT TWO AND ABOUT SIX, BY HEATING A SLURRY OF SAID SOLIDS MIXTURE IN AN AQUEOUS MINERAL ACID LEACHING-LIQUOR, SAID LEACHING-LIQUOR HAVING AN ACID CONTENT AT LEAST EQUIVALENT TO THAT AT PH 2, TO AN ELEVATED TEMPERATURE UNDER SUPERATMOSPHERIC PRESSURE AND TREATING SAID HEATED SLURRY WITH AN OXYGEN-CONTAINING GAS WHILE MAINTAINING SAID ELEVATED TEMPERATURE, SUPERATMOSPHERIC PRESSURE AND ACID CONTENT, WHEREBY SAID METAL VALUES AND DILUENT METAL ARE DISSOLVED, THE IMPROVEMENT IN SELECTIVELY CONCENTRATING SAID METAL VALUES WHICH COMPRISES: MAINTAINING SAID ELEVATED TEMPERATURE ABOVE AT LEAST ABOUT 350*F. UNTIL DISSOLUTION OF SAID NON-FERROUS METAL SUBSTANTIALLY CEASES, WHEREBY NON-FERROUS METAL IS SELECTIVELY DISSOLVED, SEPARATING RESULTANT SOLUTION FROM RESIDUAL SOLIDS, ADJUSTING THE PH OF SO-SEPARATED SOLUTION TO FROM ABOUT TWO TO ABOUT SIX, WHEREBY DISSOLVED NON-FERROUS AND DILUENT METALS ARE PRECIPITATED AS A MIXTURE WHEREIN THE RATIO OF SAID NON-FERROUS METAL TO DILUENT METAL IS INCREASED OVER THAT IN SAID SOLIDS MIXTURE, COLLECTING SAID PRECIPITATE, FORMING A SECOND SLURRY OF COLLECTED PRECIPITATE IN AN AQUEOUS MINIERAL ACID TREATING-LIQUOR HAVING AN ACID CONTENT IN EXCESS OF THAT AT PH 2, HEATING SAID SECOND SLURRY TO A TEMPERATURE ABOVE 350*F. WHEN ALUMINUM REJECTION IS NOT REQUIRED AND ABOVE ABOUT 400*F. WHEN ALUMINUM IS TO BE REJECTED, MAINTAINING SAID SECOND SLURRY AT SAID TEMPERATURE AND ACID CONTENT UNTIL DISSOLUTION OF NON-FERROUS METAL SUBSTANTIALLY CEASES AND REMOVING RESIDUAL SOLIDS, WHEREBY A SOLUTION IS OBTAINED WHEREIN THE RATIO OF DISSOLVED METAL VALUE TO DILUENTMETAL IS HIGHER THAN IN SAID PRECIPITATE.