Recommendation for lateritic Ni-ore processing: garnierite mineralogical and geochemical approach

Abstract

The objective of this study is to analyze the mineralogy and geochemistry of garnierite and its implication for Ni laterite processing. Mineralogical analysis using optical microscopic and X-ray diffraction (XRD) methods were performed, whereas chemical composition was obtained by X-ray fluorescence (XRF) method. Genetically, Ni in laterite ore is associated with SiO2 and MgO and is not accompanied by the elements of Co, Fe, Cr, Al, Mn, and Ca. In this study, Ni-laterite ore has Ni content of 2.1%, SiO2 25.42%, S/M ratio 3.7, and Fe/Ni ratio 15.5, meaning that it is more suitable to be processed by pyrometallurgical route. However, there are some characters that still have to go through treatment, namely reducing of Fe from 32.63% to 20%, increasing MgO, and reducing SiO2 by blending. Result of mineralogical analysis shows that the dominant mineral is quartz (44.8%) and talc (38.85%) with small amount of lizardite (16.35%). The high content of quartz and talc and the low in lizardite of the Ni-laterite ore in the study area indicated that it is recommended for pyrometallurgical processing which is also in accordance with its geochemical characteristics.