Geochemical Characterization Of Bedrock And Distribution Of Enrichment Of Rare Earth Elements And Scandium In Nickel Laterite Within The Wulu Area, Central Buton District, Southeast Sulawesi Province

Abstract The Wulu area has an abundance of laterite nickel mineral resources, and based on fluctuations in the chemical value of saprolite limonite zonation, it is evident that further research is required, particularly regarding the presence of REE (Rare Earth Elements) and Scandium in limonite. This study aims to examine the chemical changes of ultramafic rocks under fresh conditions in relation to the enrichment process of laterite elements and their connection to REE, especially scandium. To achieve these objectives, the research was conducted using ED-XRF and ICP-MS methods on several samples representing bedrock and laterite zoning at four locations: Block KBB_1, Block KBB_2, Block KBB_3, and Block KBB_4, to study and investigate the distribution of REE and Sc in nickel laterite. The results indicated that the wehrlite-type ultramafic source found in Block KBB_1 has the highest REE concentration at 0.91 ppm compared to lherzolite and harzburgite rocks. The increase in REE and scandium concentrations occurred significantly during the laterization of wehrlite rocks. REE and scandium concentrations were higher in the limonite zone, with concentrations increasing to 42 ppm for REE and reaching 10.63 ppm for scandium. The presence of bedrock composed of olivine and clinopyroxene minerals of wehrlite composition results in higher REE and scandium contents in the weathering products. This indicates that REE and scandium belong to the lithophile group associated with the presence of iron oxides in laterization. The difference in REE concentration of the ultramafic type is due to an imbalance in the level of laterization, such that the distribution of REE enrichment is inversely proportional; thus, high REE ultramafic types will affect the REE concentration of the laterization results. REE and scandium enrichment are directly proportional to the increase in NiO content, suggesting that REE and scandium can be by-products of nickel laterite and may be utilized in the future.