Improvements in or relating to the magnetizing roasting of oxidic iron ores

摘要

Iron ore in which the recoverable iron is present substantially in trivalent form is subjected to a reducing treatment in a rotary kiln using as reducing agent a solid finely divided petroleum coke which has been produced by coking heavy fuel oil in direct contact with the ore in the heating zone of the kiln. The fuel oil may be mixed with the ore before the latter is fed into the kiln. The rotary kiln may be equipped with jacket burners operated with an excess of air so that the quantity of oxygen supplied is at least sufficient for combustion of the volatile constituents escaping during the coking of the fuel oil. The jacket burner nearest the charging end may receive the maximum excess of air while those nearest the discharge end receive the smallest excess of air. The fine grain portion of the ore may be fed to the kiln at a point situated after its charging end and at this point additional heavy fuel oil corresponding to the fines added may be admixed prior to introduction. The reducing zone may be free of any stirring device. If desired, some of the outlet gases may be returned to the delivery end of the kiln.