Scandium enrichment in the Mandiodo nickel laterite, North Konawe, southeast Sulawesi

Abstract

Scandium is one of the heavy rare earth elements essential in various metal and energy industries. Indonesia has the potential to contain more than 4,000 tonnes of scandium, primarily in nickel laterites. The Mandiodo region is characterized by ultramafic rocks, which are part of the East Sulawesi Ophiolite complex, known for producing nickel laterite deposits. This study aims to identify indications of scandium enrichment within Mandiodo's nickel laterite deposits. Identification was conducted using pulp samples from three drill holes. Multiple analytical methods were employed to determine the geochemical properties of the laterite, weathering intensity, scandium content, mineralogical composition, mineral characteristics, rock genesis, the presence of metallic minerals in the bedrock, and scandium-bearing minerals within the bedrock. Results indicate that scandium is enriched in the limonite zone, at depths of 1-15 meters, residually with grades reaching up to 104 ppm. The scandium content shows a positive correlation with Al2O3, Fe2O3, and Cr2O3. The minerals present in the scandium-enriched zone are predominantly goethite, hematite, and talc. The content of goethite and the degree of weathering exhibit patterns similar to scandium distribution. Scandium is mainly hosted in the minerals augite and diopside, which crystallize through exsolution processes driven by temperature variations and aluminum content in the magma.