The Utilization of Pyrolyzed Palm Oil Bunch for Limonitic Laterite Ore Reduction Followed by Magnetic Separation

This study investigates the utilization of pyrolyzed Oil Palm Empty Fruit Bunch (OPEFB) as a sustainable reductant for the carbothermic reduction of limonitic laterite ore, followed by magnetic separation to concentrate iron (Fe) and nickel (Ni). Indonesia, rich in both biomass and nickel laterite resources, provides an ideal context for this research. OPEFB, a byproduct of palm oil production, was pyrolyzed at 400 °C and 600 °C and compared with coal as a benchmark reductant. The reduction process was conducted at 1150 °C for 60 min, and the resulting products were analyzed using X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDX), and thermogravimetric analysis. The results demonstrated that OPEFB charcoal effectively increased Fe content from 46.92 wt.% to 66.72–78.09 wt.% and Ni content from 0.77 wt.% to 0.96–1.26 wt.%, with recovery rates of 71.96–79.37% for Fe and 69.67–75.57% for Ni. Phase transformation analysis confirmed the reduction of Fe and Ni oxides to metallic phases, including Wüstite (FeO), non-stoichiometric FeNi alloy (Fe0.7Ni0.3), and Magnetite (Fe3O4). SEM–EDX micrographs revealed larger and more uniformly distributed FeNi alloy particles in OPEFB-treated samples compared to those in coal, suggesting that the volatile matter in biomass, particularly hydrogen, enhances reduction efficiency at high temperatures.