Utilization of low-grade BHQ iron ore by reduction roasting followed by magnetic separation for the production of magnetite-based pellet feed

Abstract

Due to the depletion of high-grade iron ores and their simultaneous demand, the utilization of low-grade iron ores such as banded hematite quartzite (BHQ) has become a topic of research interest around the globe, particularly in India. These low-grade iron ores are reckoned to be the future feedstock for iron and steel making industries. However, one of the major challenges is to remove associated gangue impurities from such low-grade iron ores by the conventional beneficiation techniques prior to its industrial applications. The reduction roasting process is one of the potential alternatives to overcome such challenges. Herein, we have presented the feasibility study using reduction roasting process on one of the Indian low-grade BHQ iron ore for the preparation of magnetite concentrate-based pellet feed materials. To establish the methodology of the reduction roasting process, different experimental parameters such as roasting temperature, reductant dosage, roasting time and fixed carbon were optimized for obtaining the maximum recovery, yield, and grade of the magnetite products. In the present study, Indian non-coking coals were used as reductant due to its large availability in the country. Using one of the non-coking coals as reductant, the optimum condition were found to be as, roasting temperature: 1100 °C, roasting time: 5 min, and head sample to reductant ratio: 10:6. Under these conditions, maximum grade and recovery of final magnetite concentrates were found to be 66.42 and 93.53%, respectively. It is expected that the large-scale development of reduction roasting process would lead to effective utilization of low and lean grade iron ore resources for the production pellet feed materials in the Indian context and simultaneously conserve the natural magnetite ores for future generation.