Evaluation of carbothermal reduction for processing of banded hematite jasper ore

Abstract

In this study, carbothermal reduction of low grade banded hematite jasper iron ore (Fe~38%) is systematically investigated. The thermodynamic calculations revealed that single phase iron oxide can be reduced to Fe at 700 °C. The thermal pretreatment at 600 °C induced significant random cracks in the underlying matrix. The carbothermal reduction was evaluated using Box Behnken statistical design and was found effective for iron enrichment. Temperature was found as significant factor for optimization of both iron grade and recovery. At a higher temperature, the formation of fayalite and wustite deteriorates the iron grade-recovery. Under optimal conditions (700 °C, 30 min, 9% charcoal, minus 75 μm) a concentrate (FeG–61.2% and FeR–82%) was obtained and can be used for blast furnace feedstock and alternative sponge iron making. Coarser particle size and alternative reductants do not have a significant effect, however, the fused fraction comprising 85%Fe with retained austenite and martensitic iron was obtained.