Experimental investigations have been made to clarify the features of the formation of combustion zones as functions of coke size and of oxygen blast rate, because these features should be crucial in forming a hot and reductive zone capable of reducing bauxites outside the combustion zone. Experimental results showed that a hot and reductive zone can be formed at the center of a blast furnace when the combustion zones are formed steadily, without growing up, within a limited space of a furnace. The use of large cokes at a high oxygen blast rate was found to be preferable for this purpose. An investigation has been made to examine an appropriate way of conveying bauxite ores into the hot and reductive region formed. The use of a large amount of calcia as flux for this purpose has been examined experimentally; however, this attempt was failed, since calcia flowed down only in the combustion zone and its vicinity. The observation that calcium oxycarbide melts became fluid in the high temperature combustion zone may imply that increasing the combustion temperature may be effective in improving the mass transfer problem intrisic to an aluminum blast furnace.
(Received December 5, 1987)
Keywords: aluminum, calcium carbide, oxygen blast, blast furnace, combustion zone, furnace temperatures, oxygen concentration
* National Chemical Laboratory for Industry, Tsukuba Research Center, Ibaraki 305, Japan.
** Central Research Laboratory of Nihon Cement Co. Ltd., 1-2-23 Kiyosumi, Kotoh-ku, Tokyo 135, Japan.