Effective Utilization of KR Slag in Iron Ore Sintering Process

Abstract

This study has been performed to understand the characteristic of KR slag, which is a by-product of the desulfurization process of steel, aiming at its effective utilization in the iron ore sintering process. KR slag contains CaO, metallic iron and FeO component and has been partly utilized in the sintering process as CaO source. However, its oxidation behavior has not been evaluated. Effective utilization of KR slag will lead to reduction of CO₂ emission by decreasing the amount of coke breeze and increase the ratio of formed melt during sintering.

Oxidation and melting behaviors of KR slag in the sintering bed were examined by using a laboratory-scale sintering simulator.

Higher oxidation ratio was obtained for KR slag than that for metallic iron particle. Iron oxide layer formed on the surface of iron particles in KR slag were easily melted and it would keep the oxidation rate of metallic iron at a certain level. The effect of mixing ratio of KR slag on the structure and permeability of the sintering bed was examined. The amount of formed melt increased with increase in the mixing ratio of KR slag.

On the other hand, when the melt ratio became to be above 15%, bed permeability was significantly decreased. This would be caused by blocking the gas flow path in the sintering bed with the excess amount of melt. Therefore, mixing ratio of KR slag is necessary to control the melt ratio below 15%.