Thermal Upgrading of A Limonite Ore from Tinanggea Area, South Konawe Regency of Southeast Sulawesi Using Coal as Reductant

Sufriadin (1*), Purwanto (1), Dandy Adrianus (1), Muhammad Zahran Mubarok (1), Akmal Saputno (2), Akane Ito (3)

Thermal Upgrading of A Limonite Ore from Tinanggea Area, South Konawe Regency of Southeast Sulawesi Using Coal as Reductant
Sufriadin (1*), Purwanto (1), Dandy Adrianus (1), Muhammad Zahran Mubarok (1), Akmal Saputno (2), Akane Ito (3)

1) Department of Mining Engineering, Faculty of Engineering, Hasanuddin University, Jl. Poros Malino KM. 6, Bontomarannu, Gowa 92171 Sulawesi Selatan, Indonesia.
*sufri.as[at]unhas.ac.id
2) Institute of Geological Science, Jagiellonian University, Golebia Street 24, 31-007 Krakow, Poland
3) Department of Earth Resources Engineering, Kyushu University, 744 Motooka, Nishi-ku Fukuoka, Japan 819-0395

Abstract

A limonite ore sample from Tinanggea Area of Southeast Sulawesi has been investigated via reduction roasting method using coal as reducing agent. The aims of this study were to find out the mineralogical and chemical characteristics of the ore, to analyse the effect of heating temperatures and dosages of reductant for the mineral transformation and the upgrading of nickel. Mineralogical and chemical characterization of the sample was performed by optical microscopy, XRD, and XRF methods respectively. Reduction roasting of limonite was done at the different temperatures (750, 850, 950, and 1050) degree C and reducing agent (5, 10, and 15) % with heating duration of 60 minutes. The results of microscopic and XRD analysis showed that limonite ore contains goethite, talc, quartz, lizardite and magnetite. Chemical composition of limonite ore determined using XRF was dominated by Fe2O3 (56.74%) followed by SiO2 (19.70%), Al2O3 (6.43%), MgO (4.05%), Cr2O3 (1.59%), MnO (0.67%), and Ni (1.43%). Roasting of limonite at 750 to 850 degree C has led to the transformation of goethite into hematite, and maghemite. Further increase of temperature at 950 degree C cause the formation of magnetite, whereas talc and lizardite were altered to forsterite. At the temperature of 1050 degree celcius, the minerals such as fayalite, spinel, and tridymite were formed. The result of reduction roasting experiment indicated that Ni could be upgraded up to 1.90% from the initial value in the ore of 1.43%, which was achieved at the roasting temperature of 1050 degree C with an addition of 15% coal reductant.

Keywords: limonite- reduction roasting- reductant- goethite- magnetite

Topic: Mining Engineering and metallurgy