Refining silver-bearing residues

Claim 1

A PROCESS FOR RECOVERING VALUES FROM SILVER MATTE CONTAINING GREATER THAN ABOUT 50% BY WEIGHT OF SILVER, BASE METAL FROM THE GROUP CONSISTING OF COPPER, NICKEL, LEAD AND SMALL AMOUNTS OF GOLD AND PLATINUM GROUP METALS WITH UP TO ABOUT 30% BY WEIGHT OF AT LEAST ONE ELEMENT SELECTED FROM THE GROUP CONSISTING OF SELENIUM AND TELLURIUM, COMPRISING INJECTING A GAS SELECTED FROM THE GROUP CONSISTING OF OXYGEN AND AIR ENRICHED WITH OXYGEN TO AT LEAST ABOUT 50% BY VOLUME INTO SAID SILVER MATTE HELD MOLTEN AT A TEMPRATURE OF ABOUT 1.090*C TO ABOUT 1,260*C IN THE ABSENCE OF A FLUX TO OXIDIZE AND VOLITLIZE SELENIUM AND TELURIUM SO AS TO PROVIDE A MATTE CONTAINING AT MOST ABOUT 0.6% BY WEIGHT TOTAL SELENIUM AND TELLURIUM, RECOVERING AT LEAST ONE MATERIAL SELECTED FROM THE GROUP OF OXIDIZED SELENIUM AND TELLURIUM FROM THE GASEOUS EFFLUENT FROM SAID GAS INJECTION PROCESS, CONTINUING SAID GAS INJECTION PROCESS IN THE ABSENCE OF A FLUX UNTIL THE MATTE IS CONVERTED TO BULLION CONTAINING AT LEAST ABOUT 85% BY WEIGHT OF SILVER, SKIMMING ANY BASE-METAL SLAG FROM THE SURFACE OF THE MOLTEN BULLION, ADDING A BORAX-SLICA FLUX AND CONTINUING OXIDATION WHILE THE MOLTEN BULLION IS IN CONTRACT WITH SAID BORAX-SILICA FLUX UNTIL THE COPPER CONTENT OF THE BULLION IS LESS THAN 1% BY WEIGHT TO PROVIDE A SILVER RICH BULLION CONTAINING GOLD AND PLATINUM GROUP METALS AND SUITABLE FOR ELECTROREFINING.