Insight of Reduction Roasting of a Low-Grade Goethitic Indian Iron Ore in a Rotary Kiln: Process Optimization and Characterization

This communication delves into a thorough examination of the reduction roasting–magnetic separation process for a low-grade Indian iron ore that is unresponsive to physical separation methods. The process was conducted in a bench-scale rotary kiln, and various parameters such as roasting temperature, roasting time, kiln rotational speed, and reductant dosage were analyzed to determine their effects on the yield and grade of the magnetic product. Additionally, characterization studies were carried out on both the feed and upgraded products to gain a better understanding of the phase transformations that occurred during the reduction roasting process. The experiments were conducted under specific conditions that included a roasting temperature between 650 and 850 °C, a roasting time of 10–60 min, a kiln rotational speed of 3–9 rpm, and a reductant dosage of 15–30%. The results showed that the low-grade iron ore could be upgraded from 56 to 65.3% Fe with a yield of 82.6% at a roasting temperature of 750 °C, a roasting time of 45 min, a kiln rotational speed of 5 rpm, and a reductant dosage of 20%. The reduction roasting experiments aided by optical and scanning electron microscopic studies helped understand the reduction sequence, while the scale-up studies indicated that the process is viable for commercial exploitation. Graphical Abstract