Effects of particle sizes and roasting temperature on the Fe-Ni enrichment of limonite ore from the Wolo mine area, Southeast Sulawesi, using corncob char as reductant

Abstract The reduction roasting of a limonite ore sample from the Wolo mine area was investigated using corncob char as a reductant. The objectives of this study were to analyze the effects of particle sizes and roasting temperature on the mineralogical transformation and Fe-Ni enrichment during the roasting process. The limonite ore was prepared into three size fractions of mesh sieves (-100+150, -150+200, and -200 mesh). Limonite ore was roasted with 2g of corn cob char reductant at temperatures ranging between 800 °C and 1100 °C with a 1-hour reduction time. Limonite ore and roasted products were analyzed to determine the mineral and chemical composition using optical microscopy, X-ray diffraction (XRD), and X-ray fluorescence (XRF) methods. Results of the mineralogical analysis indicated that the sample contained chlorite, goethite, lizardite, maghemite, and quartz. Limonite ore is mainly composed of Fe 2 O 3 (53.59%), followed by SiO 2 (12.16%), MgO (2.63%), and Ni (1.52%). Results of reduced roasting of limonite ore exhibited that the ore minerals were transformed into spinel, wustite, fayalite, and some tetrataenite (FeNi). The ore with -100+150 mesh particle and heated at 1,000 °C provided the optimum enrichment of 1.74% Ni and 42.87% Fe, respectively.