The Effect of Water Vapor on the Rate of Reduction of Iron Ore by Hydrogen

The apparatus of standard reducibility measurement of iron ore (for grains) by Gakushin was used with addition of a water vapor generator. The used Indian hematite was crushed and sieved to 5∼10 and 9∼28 mesh. The reduction rates of ore were deduced from the decreases of mass of samples by weighing. The measurements were done at the temperature range of 600°C to 900°C with respect to the temperature gradient of the rate of reduction and the relation between reduction rate and produced metallic iron pct., and at 700°C and 900°C to the ralation between the addition of water vapor to reducing gas and the rate of reduction. The results obtained were as follows: (1) The rate of reduction of hematite to magnetite was not affected by the existence of water vapor, as expected from thermodynamic calculations. (2) The rates of the later steps of reduction were decreased considerably as the ratio of partial pressures of water vapor to hydrogen was increased. (3) Particularly, the rate of the last step, the production of metallic iron, is strongly affected, and at 700°C it seemed to be negligibly small in the reducing gas containing about 30 pct water vapor.