Enhancement of reduction rate of iron ore by utilizing low grade iron ore and brown coal derived carbonaceous materials

Abstract

The reduction rate of iron ore can be enhanced dramatically when iron ore/carbon composites (IOC) are prepared so as to maximize the interfacial area and to realize intimate contact between iron ore particles and carbon. An idea realizing this concept in practical blast furnace operation was proposed in this paper. Low grade iron ore that contains a large amount of goethite, FeOOH, was chosen as an iron ore, and brown coal derivative was chosen as a thermoplastic carbonaceous material for preparing IOC sample. Goethite, FeOOH, has layered structures combined by hydrogen bonds associated with OH groups. When FeOOH is heated up to 250 to 300°C, the OH groups are removed as H2O, leaving flat pore spaces of 0.8 nm wide between 20 nm thick Fe2O 3 layers. The pore spaces are, however, closed over 300°C by the sintering of the Fe2O3 layers. The idea proposed is to insert the thermoplastic carbonaceous material into the pore space of 0.8 nm wide while the pore spaces are opened and to carbonize it to form carbon in the pore space below 500°C. This IOC is expected to realize intimate contact between the Fe2O3 layers and the carbon, and to enhance the reduction rate of the Fe2O3 dramatically. The validity of this idea was verified by preparing IOC samples using reagent grade FeOOH and a thermoplastic resin. Then it was shown that the IOC sample prepared from a low grade iron ore, SF. Robe River, and a thermoplastic extract deriving from a brown coal can realize the idea practically. © 2011 ISIJ.