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The Effect of Heating on Mineral and Chemical Composition of Saprolite Ore from Latowu Area, North Kolaka Regency of Southeast Sulawesi, Indonesia
Sufriadin
Aip Conference Proceedings
Abstract
Pre-treatment of saprolite ore as feed in the pyrometallurgical processing has been widely carried out to produce ferronickel, nickel matte, and nickel pig iron (NPI), but there are still many things that need to be known about the high temperature melting process, including the behaviour of nickel-bearing minerals of saprolite ore during high temperatures heating. This study aims to determine the mineral and chemical composition of saprolite ore and its effect on the calcination temperature. Saprolite ore sample with 200 mesh size was heated at 200°C, 400°C, 600°C, 800°C, and 1000°C. Sample before and after heating was analysed for minerals/phases change and variations of chemical composition using the X-ray diffraction (XRD) and X-ray fluorescence (XRF) methods respectively. The results of mineralogical analysis show that saprolite sample contain talc, quartz, lizardite, illite, hematite, and montmorillonite. Chemical compositions of saprolite ore are dominated by SiO2 (40.65%), MgO (35.84%), Fe2O3 (15.94%) with a small amount of Al2O3 (3.50%), CaO (1.62%), Cr2O3 (1.21%), NiO (1.20%) and MnO (0.40%). Heating of the sample has a major influence on the formation of new minerals in the sample. Minerals occurred after calcination, namely maghemite [γ-Fe2O3] formed at 400°C, β-quartz at 600°C, enstatite [MgSiO3] at 800°C, and tridymite [SiO2] at 1000°C. Calcination has also reduced of about a quarter of sample into the calcined ore with the highest NiO concentration was achieved at the calcination temperatures of 400°C.