Method for roasting sulfides

Claim 1

A PROCESS FOR THE TREATMENT OF FINELY DIVIDED NICKEL SULFIDE MATERIAL, CONTAINING MORE THAN ABOUT 15% SULFUR AND OBTAINED FROM MATTES AND MATTE FLOTATION PRODUCTS, FOR FORMATION OF A SUBSTANTIALLY COMPLETELY GRANULAR, ROASTED, NICKEL OXIDE PRODUCT THEREFROM, SAID NICKEL SULFIDE MATERIAL CONTAINING MINOR AMOUNTS OF IRON AND MINOR AMOUNTS OF AT LEAST ONE ELEMENT FROM THE GROUP CONSISTING OF COPPER AND COBALT AND THE BALANCE SUBSTANTIALLY ALL SULFUR, WHICH COMPRISES AGGLOMERATING SAID SULFIDE MATERIAL WITH WATER TO FORM GANULES WITH A PARTICLE SIZE OF BETWEEN ABOUT 65 MESH AND ABOUT 0.5 INCH. FEEDING SAID GRANULES TO A FLUEL BED REACTION ZONE IN WHICH SAID SULFIDE MATERIAL IS OXIDIZED AT A TEMPERATURE AT LEAST ABOUT 20*F. ABOVE THE SOFTENING POINT OF THE SULFIDE MATERIAL AND BELOW THE MELTING POINT OF THE RESULTING OXIDE PRODUCT IN AN OXYGEN-CONTAINING GAS SUPPLIED TO SAID REACTION ZONE AT A FLUIDIZING RATE SUFFICIENTLY HIGH THE ELUTRIATE FINES FROM THE BED WHILE MAINTAINING THE COARSER MATERIAL IN A FLUIDIZED CONDITION TO INSURE RAPID AND SUBSTANTIALLY COMPLETE OXIDATION TO LESS THAN ABOUT 2% SULFUR AND TO PRODUCT A COARSE, SUBSTANTIALLY COMPLETLY GRANULAR, OXIDE PRODUCT WITH A PARTICLE SIZE NOT LARGER THAN THAT OF THE SULFIDE GRANULES FED TO SAID REACTION ZONE, SEPARATING FINE CALCINE DUST FROM THE REACTION EXHAUST GASES AND RETURNING SAID SEPARATED DUST TO THE AGGLOMERATING STEP.