2011 Volume 51 Issue 8 Pages 1227-1233
Decreasing the thermal reserve zone temperature is believed to increase the energy efficiency of blast furnace iron-making. To do so, either the direct reduction reaction rate or the coke gasification reaction rate must be significantly increased below 1000°C in CO-lean atmosphere. An iron ore/carbon composite (IOC) has been proposed as a new raw material that can enhance the reduction rate of iron ore. In this paper the possibility of the reduction rate enhancement was examined by preparing a kind of ideal IOC sample consisting of nano-sized Fe2O3 particles (10–70 nm in diameter) and a carbon material prepared from a thermoplastic resin. The nano-sized Fe2O3 particles in the IOC sample were surprisingly reduced to Fe in a few minutes at as low as 650°C in an inert atmosphere. This was realized by increasing the interfacial area between the Fe2O3 particles and carbon and by establishing intimate contact between the two. The carbon in the IOC sample was also completely gasified in less than 10 minutes at as low as 750°C in a CO2 atmosphere. The dramatic enhancement of the gasification rate was found to be realized by the enhancement of one of the direct reduction reactions, the reaction between Fe3O4 particles and carbon, by the aid of in-situ XRD measurement. This suggested that the enhancement of both the reduction reaction rate and the gasification reaction rate is realized by the same mechanism. These new findings will give a clue for designing IOC samples applicable to the blast furnace iron-making.
