Influence of roasting characteristics on gas-based direct reduction behavior of Hongge vanadium titanomagnetite pellet with simulated shaft furnace gases

摘要

In the present work, the correlations between roasting characteristics of Hongge vanadium titanomagnetite pellet (HVTMP) and its subsequent reduction behaviors were investigated with simulated shaft furnace gases. The results showed that the compressive strength of HVTMP increased with the increase of roasting temperature and roasting time. Increasing roasting temperature and roasting time accelerated its subsequent reduction, however, the reduction rate decreased when the pellets roasted at 1250 degrees C were used. The roasting conditions of oxidized pellets had a slight effect on the phase compositions of the reduced pellets. The severest reduction swelling was observed when the pellets roasted at 1050 degrees C were adopted. The abnormal swelling could be suppressed by increasing the roasting temperature and roasting time. Moreover, abnormal swelling was caused by the forming of a large number of metallic iron whiskers during gas-based direct reduction. A conceptual diagram was formulated to describe the swelling mechanism at different roasting conditions. In practical industrial production of HVTMP, the roasting conditions should be optimized as far as possible to improve the reduction swelling under the prerequisite of meeting the compressive strength of the HVTMP smelting in the gas-based shaft furnace. This study aims to provide both theoretical and technical basis for the effective utilization of HVTM in either blast furnace or shaft furnace. (C) 2017 Elsevier B.V. All tights reserved.