A model for the isothermal reduction of iron ore with coal char

Of the various commercially successful processes for direct reduction of iron ore, rotary kiln processes have been found to be the most promising under the Indian context. Reduction of iron ore by coal in a rotary kiln takes place in two stages: (a) reduction of iron ore by carbon monoxide: Fe₂O₃+3CO=2Fe+3CO₂; (b) gasification of carbon of coal by CO₂:C+CO₂=2CO. In the present paper, kinetic equations have been developed for reduction of iron oxide by carbon monoxide and gasification of coal char by carbon dioxide. These kinetic equations have been used to develop a mathematical model for reduction of iron ore with coal char in a rotary kiln. The model can predict the degree of reduction () with time (t) at a given temperature of solid (T_s) and the ratio of fixed carbon to total iron content in the charge (C_fix/Fe(T)) for reduction of iron ore with coal char of known reducibility and reactivity, respectively. The values of the degree of reduction predicted by the model have been compared with the results of the experiments conducted in a laboratory rotary kiln.