Abstract
The use of magnetisation roasting followed by magnetic separation has become a promising separation technology to produce iron concentrate from low-grade ores and secondary iron sources. The paper investigates the influence of different parameters, roasting temperature, roasting time, and reducing agents: coal-based and macadamia nutshells, on the phase transformation of the low-grade iron plant tailing during magnetisation roasting. The study used Mössbauer spectroscopy and XRD to identify and quantify the transformation of hematite to magnetite. The optimal conditions were found to be a roasting temperature of 950 ℃ and a roasting time of 60 minutes for both types of reductants. The recovery of iron using macadamia nutshell reductant was 42.16%. In comparison, only 23.37% was obtained using coal-based reductant, in which a concentrate with an iron grade of 66.92% for macadamia nutshell and 67.15% for coal-based was obtained – making macadamia nutshell a suitable and an alternative reductant for magnetisation roasting.