Rate of reduction of ore-carbon composites: Part I. Determination of intrinsic rate constants

A process for ironmaking was proposed consisting of the combination of a rotary hearth furnace and bath smelter employing wood charcoal as reductant and energy source. This article examines reactions in composites of iron oxides and carbon at elevated temperatures in conditions developed to minimize the influence of mass and heat transfer to the overall rates. A combined reaction model considering the steps of carbon oxidation and reduction of the iron oxides was developed allowing the measurement of rate constants for carbon oxidation and wustite reduction to be used in a comprehensive pellet model developed in Part II of the current article. This analysis showed that wustite reduction can have a significant effect on the overall rate of reduction in composites at high temperatures or in the presence of large excess of carbon. Rate constants measured for graphite showed that graphite is as reactive as wood charcoal, possibly due to the catalysis of graphite or its higher temperature dependence. The poisoning of carbon surfaces by CO is less significant than anticipated from works of previous authors.