Smelting of zinciferous ore

Claim 1

THE METHOD OF SMELTING AN OXIDIC ZINCIFEROUS ORE WITH SOLID CARBONACEOUS REDUCING MATERIAL IN AN ELECTRIC FURNACE WITH THE RESULTING PRODUCTION OF A SUBSTANTIALLY ZINC-FREE MOLTEN SLAG AND METALLIC ZINC VAPOR WHICH COMPRISES INTRODUCING INTO THE FURNACE A CHARGE COMPRISING THE ZINCIFEROUS ORE, IRON OXIDE AND AN AMOUNT OF SAID REDUCING MATERIAL SUFFICIENT TO EFFECT REDUCTION OF ALL OF THE ZINC OXIDE COMPONENT OF THE ORE TO METALLIC ZINC AND TO EFFECT REDUCTION OF SUCH AN AMOUNT OF THE IRON OXIDE AS TO FORM A BODY OF MOLTEN IRON PRODUCT UNDERLYING SAID SLAG BUT TO LEAVE IN THE SLAG AT LEAST 11/2% AND NOT MORE THAN ABOUT 6% BY WEIGHT OF IRON OXIDE (CALCULATED AS FE), FURTHER INCORPORATING IN THE CHARGE A SLAG-FORMING MATERIAL OF THE GROUP CONSISTING OF LIME AND SILICA IN AMOUNT SUCH AS TO PROVIDE A LIME TO SILICA RATIO COMING WITHIN THE RANGE OF 0.8:1 TO 1.4:1 SO AS TO IMPART TO THE SLAG A FLUIDITY WITHIN A TEMPERATURE RANGE OF ABOUT 1100* TO 1450* C. SUFFICIENT TO PROMOTE APPRECIABLE THERMAL CONVECTION CIRCULATION WITHIN THE SLAG LAYER, THE CHARGE INTRODUCED INTO THE FURNACE BEING IN THE FORM OF A LOOSE MASS OF DISCRETE PARTICLES AND ITS RATE OF INTRODUCTION BEING SUCH AS TO PERMIT THE CHARGE TO FLOAT ON THE SURFACE OF THE SLAG AND BE HEATED TO SMELTING TEMPERATURE BY CONTACT WITH THE SLAG, AND SUPPLYING HEAT TO THE SLAG SO AS TO MAINTAIN A SLAG TEMPERATURE NOT IN EXCESS OF 1450* C. BUT SUFFICIENT TO EFFECT SAID SMELTING OF THE CHARGE WHILE FLOATING ON THE SLAG BY SUBMERGING THE FURNACE ELECTRODES IN THE MOLTEN SLAG TO SUCH AN EXTENT AS TO HEAT THE SLAG BY A COMBINATION OF SUBMERGED ARC AND SLAG RESISTANCE HEATING AND THEREBY AVOIDING EXPOSURE OF THE FLOATING CHANGE TO AN OPEN ARC, SAID SMELTING OF THE FLOATING CHARGE RESULTING IN THE FORMATION OF SMELTING GASES CONTAINING METALLIC ZINC VAPOR FREE FROM SUCH AN AMOUNT OF VOLATILIZED DUST-FORMING IMPURITIES AS TO APPRECIABLY INTERFERE WITH THE CONDENSATION OF THE ZINC VAPOR TO MOLTEN METAL.

Claim 2

THE METHOD OF SMELTING AN OXIDIC ZINCIFEROUS ORE WITH SOLID CARBONACEOUS REDUCING MATERIAL IN AN ELECTRIC FURNACE WITH THE RESULTING PRODUCTION OF A SUBSTANTIALLY ZINC-FREE MOLTEN SLAG AND METALLIC ZINC VAPOR WHICH COMPRISES INTRODUCING INTO THE FURNACE A CHARGE COMPRISING THE ZINCIFEROUS ORE, IRON OXIDE AND AN AMOUNT OF SAID REDUCING MATERIAL SUFFICIENT TO EFFECT REDUCTION OF ALL OF THE ZINC OXIDE COMPONENT OF THE ORE TO METALLIC ZINC AND TO EFFECT REDUCTION OF SUCH AN AMOUNT OF THE IRON OXIDE AS TO FORM A BODY OF MOLTEN IRON PRODUCT UNDERLYING SAID SLAG BUT TO LEAVE IN THE SLAG AT LEAST 11/2% AND NOT MORE THAN ABOUT 6% BY WEIGHT OF IRON OXIDE (CALCULATED AS FE), FURTHER INCORPORATING IN THE CHARGE A SLAG-FORMING MATERIAL OF THE GROUP CONSISTING OF LIME AND SILICA IN AMOUNT SUCH AS TO PROVIDE A LIME TO SILICA RATIO COMING WITHIN THE RANGE OF 0.8:1 TO 1.4:1 SO AS TO IMPART TO THE SLAG A FLUIDITY WITHIN A TEMPERATURE RANGE OF ABOUT 1100* TO 1450* C. SUFFICIENT TO PROMOTE APPRECIABLE THERMAL CONVECTION CIRCULATION WITHIN THE SLAG LAYER, THE CHARGE INTRODUCED INTO THE FURNACE BEING IN THE FORM OF A LOOSE MASS OF DISCRETE PARTICLES AND ITS RATE OF INTRODUCTION BEING SUCH AS TO PERMIT THE CHARGE TO FLOAT ON THE SURFACE OF THE SLAG AND BE HEATED TO SMELTING TEMPERATURE BY CONTACT WITH THE SLAG, AND SUPPLYING HEAT TO THE SLAG SO AS TO MAINTAIN A SLAG TEMPERATURE NOT IN EXCESS OF 1450* C. BUT SUFFICIENT TO EFFECT SAID SMELTING OF THE CHARGE WHILE FLOATING ON THE SLAG BY SUBMERGING THE FURNACE ELECTRODES IN THE MOLTEN SLAG TO SUCH AN EXTENT AS TO HEAT THE SLAG BY A COMBINATION OF SUBMERGED ARC AND SLAG RESISTANCE HEATING AND THEREBY AVOIDING EXPOSURE OF THE FLOATING CHANGE TO AN OPEN ARC, SAID SMELTING OF THE FLOATING CHARGE RESULTING IN THE FORMATION OF SMELTING GASES CONTAINING METALLIC ZINC VAPOR FREE FROM SUCH AN AMOUNT OF VOLATILIZED DUST-FORMING IMPURITIES AS TO APPRECIABLY INTERFERE WITH THE CONDENSATION OF THE ZINC VAPOR TO MOLTEN METAL.