Production of molten pig iron from fine grained iron ore, Fuel and Limestone

Abstract

In view of the well-known dependence of iron blast furnace on metallurgical coke, large number of alternative iron-making techniques have been evolved, most of which produce sponge iron. Despite the high thermal efficiency of iron blast furnace, due to thermodynamics of reduction reactions, a substantial amount of costly coke finds its way as blast furnace gas of very poor calorific value. Bearing these deficiencies in mind, possibilities of producing molten pig iron in an experimental revolving furnace. The carbon monoxide evolved by the direct reduction of iron oxide by carbon was totally burnt inside the furnace by oxygen for supplying the thermal requirements of the chemical reactions involved and the gases leaving the furnace did not have any chemical heat value. The operational parameters comprising the establishment of optimum fuel rate with different solid fuels, oxygen injection, supplementary requirement of fuel oil for maintaining the temperature of the vessel were determined. The effect of basicity degree of slag conducted with acid and basic refractory linings of the furnace on the chemistry of the pig iron was studied. The effect of preheating of the charge on the fuel rate was assessed. The ability to use the fine-grained raw materials and the complete utilisation of fuel in the furnace economized the cost of production despite the requirement of oxygen. The wear on the monolithic refractory lining was severe. Further tests in a suitably designed and refractory-lined revolving furnace were considered essential for ascertaining commercial viability of the process. (Shri R. Santokh Singh, Scientist; and Shri P.S. Virdhi, Senior Technical Assistant; National Metallurgical Laboratory. Dr. A.B. Chatterjea, formerly Deputy Director, National Metallurgical Laboratory; presently with M/s M.N. Dastur and Co. Pvt. Ltd., Calcutta)