Abstract
Volatile matter (V.M.) is released in the course of carbonization of coal under a rising temperature condition. The kind and amount of V.M. depend on the kind of coal. Components of V.M. are tar, hydrocarbons (CH4, C2H4, C2H6, C3H8), CO, CO2 and H2, which are released in this order as a function of carbonization temperature. When the carbonization of coal under a rising temperature condition is interrupted at a maximum carbonization temperature, TC, max, semi-coal-char with residual V.M. is obtained. If some optimum interruption-temperature is chosen, small but most suitable amount of V.M. is retained. When the semi-coal-char thus obtained is heated again under the same rising temperature conditions but up to more than TC, max, the residual V.M. is released from just around TC, max. We propose novel iron ore agglomerate bearing such semi-coal-char with some strength in order to decrease the initial temperature for reduction of iron oxide under a rising temperature condition, such as in a blast furnace shaft. The carbonization of Newcastle blend coal under a rising temperature condition was interrupted at TC, max = 823, 873, 1073, 1173 and 1273 K, to obtain semi-coal-char with some residual V.M. Thus obtained semi-coal-char at TC, max = 823 K retained much amount of V.M, most of which was H2. The semi-coal-char was mixed with reagent grade hematite in the mass ratio of one to four, and added with a Bentonite of 1 mass% as a binder. The carbon composite pellets bearing the semi-coal-char were prepared and reduced from room temperature to maximum reduction temperatures, TR, max = 873, 973, 1073, 1173 and 1273 K, at 3 K min-1 in the nitrogen gas atmosphere. It was confirmed by the gas chromatography of gas generated by reduction of pellets that the carbon composite pellets bearing the semi-coal-char at TC, max = 823 K had the highest reducibility of the iron oxide; the original Fe2O3 was mainly changed to Fe3O4 at TR, max = 973 K and 1073 K, to FeO at 1173 K and to Fe at 1273 K.
