The Characteristic of a Thick Slag Layer and Mechanism of Reduction of Iron Ore in the Smelting Reduction

摘要

It was reported that the reduction rate constant of iron ore increased with increasing of the amount of slag in the smelting reduction with a thick slag layer. However, its mechanism was not clear.In this study, distributions of metal droplets and carbonaceous materials in the slag layer were investigated with a l00t converter and the mechanism of reduction of iron ore was discussed. The obtained results were as follows:(1) Considered from the distributions above, 44 percent of iron oxide was reduced at the metal surface in the lower 30 percent of the slag layer, 6 percent of theta was reduced at the metal surface in the upper 70 percent of the slag layer and 50 percent of that was reduced at the surface of the carbonaceous materials in the slag.(2) For achieving high productivity keeping high post-combustion ratio, low dust formation and a stable operation without slag foaming, the following methods are useful.(i) keeping a large amount of slag.(ii) keeping a large amount of carbonaceous materials in the slag.(iii) controlling the bottom stirring to surpress the amount of metal droplets in the upper 70 percent of slag layer.