Hydrogen affection on softening and melting behaviours of high alumina sinter in gas-injection blast furnace

Abstract

As the Al₂O₃ content increasing in iron ore, some problems presented in blast furnace (BF) processing, such as worsened burden permeability and slag viscosity. Injection of H₂ may improve the permeability and reduce the CO₂ emission of BF, because of its less density and higher reduction potential when temperature is higher than 820 °C. Therefore, the influence of H₂ concentration on the softening and melting behaviour of high alumina sinter is a worth investigate topic. In this article, the high alumina sintering samples with Al₂O₃ content of 2.11 wt% are investigated in a specially designed experimental apparatus capable of continuously changing pressure on the burden. The results show that the softening temperature range of the samples is expanded and their melting temperature range is reduced with the increasing of H₂ concentration from 0 vol% to 20 vol% in reduction gas. But the overall change on softening-melting temperature range is just from 280 °C to 310 °C, which is relatively small comparing with other references reported results. The addition of H₂ promotes the reduction of FeO and is conducive to separate between the iron phase and slag phase before the charge droplet formation, which facilitates the aggregation and precipitation of metallic iron in soften state. Simultaneously, higher H₂ concentration leads to more pronounced improvements in the permeability of the high alumina burden.