ANALYSIS OF COBALT (CO) AND SCANDIUM (SC) ABUNDANCE AND THEIR DISTRIBUTION IN LATERITE NICKEL DEPOSITS IN TAPUNOPAKA REGION, NORTH KONAWE, SOUTHEAST SULAWESI

• Main Author: Kurniadi, Adelia
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69541
• Institution: Institut Teknologi Bandung

Sulawesi Island is the result of a series of collision events that caused the ultramafic rocks of the ophiolite complex to be exposed. The tropical climate, warm temperatures, and high rainfall allow chemical weathering to run intensively on ultramafic rocks to form laterite nickel deposits. Besides nickel, these deposits also contain other important metals such as scandium (Sc) and cobalt (Co). The latter elements can be concentrated in the limonite zone during weathering as a consequence of residual enrichment. However, the resources of these two metals have not been optimally utilized and are only a by-product in primary ore processing. Therefore, to meet the growing demand for Co and Sc metals, it is necessary to identify the control of their abundance and their distribution in laterite nickel deposits in the Tapunopaka Prospect so that optimal mineral conservation efforts can be carried out. This study aims to determine the zoning characteristics of laterite nickel deposits and their relationship to the abundance of Co and Sc, to determine the control of Co and Sc abundances, and to determine the local distribution of Co and Sc elements in laterite nickel deposits in the study area. The data used are primary data in the form of 5 rock samples and petrography, as well as secondary data in the form of geochemical data for 39 drill points (XRF at 39 drill points and XRF and ICP-MS at 15 drill points), drill core photos from 1 drill point, Digital Elevation Models (DEM), and geological maps. The profile of laterite nickel deposits in the study area is divided into four zones: topsoil, limonite, saprolite, and bedrock. The bedrock in the study area consists of dunite and harzburgite. The research area has experienced strong laterization with a pattern towards Fe2O3 enrichment. In the laterite profile, Co and Sc are mainly concentrated in the limonite zone. Spearman Correlation analysis showed that the element Co has a strong positive relationship with MnO; while Sc has a strong positive correlation with Fe2O3 and TiO2 and is moderately positive with Cr2O3 and Al2O3. The abundance of Co in the limonite zone is influenced by topography, bedrock type, and limonite thickness. Limonite in a flat and slight slope topography has a relatively higher Co content. Dunite contains higher Co than harzburgite, resulting in limonite with higher Co contents. In addition, the thicker the limonite, the higher the Co concentration in that zone. Similar to Co, the abundance of Sc in the limonite zone is also influenced by topography, bedrock type, and limonite thickness. Limonite in a slight slope topography has a relatively higher concentration of Sc. Harzburgite contains a higher Sc than dunite, resulting in limonite with a higher Sc content. In addition, the thicker the limonite, the higher the Sc concentration in the zone. The estimation of Co and Sc distributions around the drill point was obtained using the Inverse Distance Weighting (IDW) method. Based on this analysis, the results show that highest Co concentrations in the limonite zone are observed in the southeastern part of the study area, preferentially in a flat to slight slope topography and hosted by dunite. The concentration of Sc in the study area is dominated by values >70 ppm. The lowest Sc concentration (<50 ppm) is observed in the south-southeast part of the study area, preferentially in an intermediate slope topography and hosted by dunite.