Production of gases containing sulfur dioxide

Claim 1

IN A FLUIDIZED BED PROCESS FOR ROASTING A SULDIDIC IRON ORE CONTAINING AT LEAST ONE OF THE ELEMENTS ARSENIC AND ANTIMONY WITH A FREE IXYGEN-CONTAINING GAS TO PRODUCE SULFUR DIOXIDE THE IMPAROVEMENT FOR PRODUCING COMPLETELY ROASTED SOLID RESIDUE SUBSTANTIALLY FREE OF SAID ELEMENTS WHICH COMPRISES CONDUCTING THE ROASTING IN A PLURALITY OF SEPARATE FLUIDIZED BED ROASTING STAGES, PRELIMINARILY ROASTING SAID ORE IN A FIRST SAID STAGE TO PRODUCE SULFUR DIOXIDE AND VOLTAILIZE SAID ELEMENTS, LIMITING SAID PRELIMINARY ROASTING TO THE PRODUCTION OF INTERMEDIATE ROASTED SOLID MATERIAL CONTAINING A MINIMUM OF ABOUT 3% BY WEIGHT OF SULFIDIC SULFUR WHILE BEING SUBSTANTIALLY FREE OF SAID ELEMENTS, COMPLETELY ROASTING SAID INTERMEDIATE MATERIAL IN AT LEAST ONE ADDITIONAL SAID STAGE TO PRODUCE SAID ROASTED RESIDUE CONTAINING FERRIC OXIDE, SUPPLYING SAID OXYGEN-CONTAINING GAS TO SAID FIARST STAGE AND TO SAID ADDITIONAL STAGE WITH THE SUPPLY TO EACH STAGE SEPARATE FROM AND INDEPENDENT OF THE OTHER, AFTER EACH SAID STAGE SEPARATELY WITHDRAWING THE ROASTER GAS PRODUCED IN EACH STAGE FROM THE ROASTING PROCESS, AND WITH DRAWING SAID COMPLETELY ROASTED RESIDUE CONTAINING FERRIC OXIDE FROM THE ROASTING PROCESS, WHEREBY EXHAUST GASES ARE NOT COMINGLED AND NOT CONTACTED WITH OTHER STAGES AND ROASTED RESIDUE IS PREVENTED FROM ENTERING SAID FIRST STAGE, TO PREVENT REACTION AND BINDING OF SAID ELEMENTS WITH FERRIC OXIDE.