Gas replacement of metal sulfides

Claim 1

IN A METHOD OF TREATING AN ORE CONCENTRATE, CONTANING (A) A PLURALITY OF NON-FERRROUS METAL VALUES, (B) ACID-INSOLUBLE GANGUE AND (C) AT LEAST ONE DILUENT METAL, INCLUDING THE STEPS OF SUBJECTING THE ORE CONCENTRATE TO A LEACHING OPERATION, WHEREBY SUBSTANTIALLY ALL THE NON-FERROUS METAL VALUES AND AT LEAST PART OF THE DILUENT METAL ARE DISSOLVED AS SOLUBLE SALTS IN AQUEOUS INORGANIC ACID SOLUTION, REMOVING THE RESIDUAL UNDISSOLVED SOLIDS AND PRECIPITATING FROM RESULTANT SOLUTION AT LEAST ONE NON-FERROUS METAL VALUE AS AN INSOLUBLE SULFIDE THEREOF; THE IMPROVEMENT WHICH COMPRISES; TREATING SAID CLARIFIED SOLUTION IN A PRIMARY REPLACEMENT UNDER ACID CONDITIONS SIMULTANEOUSLY WITH (A) AT LEAST ONE REPLACEMENT METAL SULFIDE, THE SOLUBILITY OF THE LEAST SOLUBLE REPLACEMENT SULFIDE, AT THE REPLACEMENT ACIDITY, BEING GREATER THAN THAT OF THE SULFIDE OF AT LEAST ONE NON-FERROUS METAL VALUE TO BE PRECIPITATED BUT NOT GREATER THAN THAT OF THE SULFIDE OF ANY DILUENT METAL, AND (B) REDUCING AGENT IN SUFFICIENT AMOUNT TO INSURE SUBSTANTIALLY NO OXIDATION OF SULFIDE IONS TO FREE SULFUR, WHEREBY AT LEAST ONE DISSOLVED NON-FERROUS METAL IS PRECIPITATED AS METAL SULFIDE; CONTINUING TREATMENT UNTIL NON-FERROUS METAL SULFIDE PRECIPITATION SUBSTANTIALLY CEASES AND COLLECTING RESULTANT SULFIDE PRECIPITATE.