Smelting metal oxide compacts in shaft furnace - using non-coking carbonaceous reductant and controlled combustion conditions

摘要

Compacts are formed from a mixture of metal oxide, solid carbonaceous matter of low volatile matter content, flux and binder, the carbon content exceeding that required for complete redn. of the metal oxide by the amt. desired for combustion. The compacts are charged to a shaft furnace where the excess carbon is burnt by air introduced through primary tuyeres located near the base of the shaft. The combustion conditions are such that no raceway or cavity is formed at any tuyere, that the space velocity of the combustion air referred to the emply shaft at normal temperature and pressure is 200 ft/min. and that primary combustion is predominantly to CO2. Oxygen contg. gas may be introduced independently through auxiliary tuyeres at a higher level to burn carbon monoxide. The invention is directed partic. to the reduction of Fe-bearing material, either ores or furnace dusts. It reduces costs by eliminating the need for coke and using instead non-coking materials. The low volatile content of the latter aluminates clogging of the upper part of the furnace by tar condensation.