Thermal Beneficiation of a Nickel Laterite Ore from the Obi Island of North Maluku, Indonesia Using Corncob Char as Reductant

A nickel laterite ore sample from the Obi Island of North Maluku, Indonesia was thermally treated using corncob charcoal as a reductant to determine the effect of corncob charcoal addition on the chemical change and phase transformation. Mineralogical analysis of raw ore sample and calcines was performed using optical microscopy and X-ray diffraction methods, whereas chemical composition was determined employing X-ray fluorescence (XRF) spectrometry. The ore was then calcined at 1.000°C for 1 hour with the mass variable of corncob charcoal as reductant was 5,10,15, and 20%. After calcination, the products were then weighed and analyzed using microscopic, XRD, and XRF methods. The results of material characterization showed that the ore sample is dominated by goethite. Antigorite, quartz, and hematite are also present in small quantities. The ore sample contains 1.53% Ni, 18.84% Fe, and an SM ratio of 2.46%. The experimental results showed that the optimum condition was achieved with the addition of 10% corncob reductant where the calcined product contains 1.88% Ni, 14.22% Fe, and SM ratio of 1.72. The increase of corncob charcoal addition >10% resulted in slight decrease of Ni reduction likely due to increase of Fe metallization.