Process for the production of ferromanganese from low-grade manganese-bearing materials

Claim 1

IN A PROCESS FOR PRODUCING A FERROMANGANESE PRODUCT FROM ORE COMPRISING OXIDES OF MANGANESE, IRON, CALCIUM, AND SILICA, THE IMPROVEMENT WHICH COMPRISES PASSING THE ORE IN THE FORM OF A CALCINED, SUBSTANTIALLY CONSTANT COMPOSITION CHARGE INTO A FIRST COVERED ELECTRIC FURNACE AND ONTO THE SURFACE OF A MOLTEN SLAG BATH MAINTAINED THEREIN, SUBJECTING THE CHARGE TO THE ACTION OF A CONTROLLED AMOUNT OF A SOLID CARBONACEOUS REDUCING AGENT WITHIN THE FURNACE, AT A CONTROLLED TEMPERATURE WITHIN THE RANGE 1300*C.-1500*C. TO EFFECT SELECTIVE REDUCTION TO THE METALLIC STATE OF A MAJOR PORTION OF THE IRON OF THE ORE WITH THE PRODUCTION OF MOLTEN METALLIC IRON AND MOLTEN SLAG CONTAINING SUBSTANTIALLY ALL OF THE MANGANESE OF THE ORIGINAL ORE IN THE FORM OF MANGANESE SILICATE, SEPARATING THE MOLTEN METALLIC IRON FROM THE MOLTEN SLAG, PASSING THE MOLTEN SLAG INTO A SECOND COVERED ELECTRIC FURNACE AND ONTO THE SURFACE OF A MOLTEN SLAG BATH MAINTAINED THEREIN, SUBJECTING THE SLAG TO THE ACTION OF A CONTROLLED AMOUNT OF A SOLID CARBONACEOUS REDUCING AGENT AT A CONTROLLED TEMPERATURE WITHIN THE RANGE 1300*C.-1500*C. TO EFFECT REDUCTION TO THE METALLIC STATE OF SUBSTANTIALLY ALL OF THE MANGANESE CONTAINED THEREIN AND THE REMAINDER OF THE IRON OF THE ORIGINAL ORE WITH THE PRODUCTION OF A MOLTEN FERROMANGANESE PRODUCT AND MOLTEN RESIDUAL SLAG, AND SEPARATING AND RECOVERING THE MOLTEN FERROMANGANESE PRODUCT FROM THE MOLTEN RESIDUAL SLAG, THE TEMPERATURES WITHIN BOTH FURNACES BEING CONTROLLED WITHIN THE RANGE 1300*C.1500*C. DURING THE COURSE OF THE PROCESS BY MAINTAINING THE ARCING TIPS OF THE FURNACE ELECTRODES BETWEEN ABOUT ONE-HALF INCH (1/2") FROM THE UPPER SURFACES OF THE MOLTEN SLAG BATHS THEREIN AND ABOUT THREE INCHES (3") BELOW THE UPPER SURFACES OF SAID MOLTEN SLAG BATHS, THEREBY TO EFFECT COMBINED ARC RESISTANCE AND SLAG RESISTANCE HEATING.