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The reduction of iron oxide fines to wustite between 590°C and 1000°C with a CO-CO 2 gas mixture of low reducing potential was studied. The reduction kinetics and the dominating reaction mechanism varied with the temperature, extent of reduction, and type of iron oxide. Reduction from hematite to wustite proceeded in two consecutive reaction steps with magnetite as an intermediate oxide. The first reduction step (hematite to magnetite) was fast and controlled by external gas mass transfer independently of the oxide type and the temperature employed. The second reduction step (magnetite to wustite) was the overall reaction-controlling step, and the reduction mechanism varied with the temperature and the oxide type. Moderately porous oxide fines followed the uniform internal reaction for the temperature range studied. For highly porous oxides, the second reduction step was controlled by external gas mass transfer above 700°C. Below that temperature, a mixed regime that involves external gas mass transfer and limited mixed control, which comprises pore diffusion and chemical reaction, takes place. The rate equations for this mixed control reaction mechanism were developed, and the limited mixed control rate constant (k lm ) was computed. For denser oxides under uniform internal reaction, the product of the rate constant and pore surface area (kAES) was calculated.

Foaming in the electric arc furnace is achieved by injecting carbon into slag, where the resulting reaction of the carbon with FeO dissolved in the slag generates gas (CO) that causes the slag to foam. In this research, the rate of the reaction of FeO in slag with carbon and the resulting foam height were measured. In these experiments, the FeO content of the slag ranged from 15 to 45 mass pct, and several different types of carbon were used including graphite, coals, and chars. The rate of the slag-carbon reaction and the consequent CO generation increased with FeO content of the slag from 15 to 45 mass pct. However, the slag foam height reached a maximum at about 25 mass pct FeO and decreased at higher FeO contents. The decrease in foaming is apparently due to a decrease in the foam index or foamability caused by a decrease in viscosity and an increase in density of the slag with FeO content. The results of this work indicate that the foam height is influenced more significantly by the decrease in the foam index compared to the increase in the CO gas generation rate at higher FeO contents. The decrease in the foam index with FeO agrees with that predicted from the slag properties.