LEACHING TIME CORRELATION WITH HEAVY METALS (Fe, Cr, Ni, Mn) DISTRIBUTION IN FERRONICKEL SLAG LEACHING TEST

Ferronickel slag (FNS) is solid byproducts from ferronickel smelter. It has been used in construction fields as compaction material in road construction and concrete construction. This study aims to characterize the ferronickel slag physical, chemical and leaching potential, identify the soil properties in the study area, and the chromium content in the leachate by conducting leaching test through soil columns in the laboratory. Methods used in this study were TCLP, X-Ray Fluorescence and X-Ray Diffraction. Soil samples were taken from three locations, i.e. settlement area, plantation area, and harbor area and the ferronickel slag samples from the stockpile nearby the ferronickel plant in Pomalaa District, Southeast Sulawesi, Indonesia. The results showed that in the soil surface of settlement and plantation area, the correlation between leaching time and heavy metals (Fe, Cr, Ni, Mn) concentration are positive strong – very strong, while soil from harbor area showed negative strong – very strong correlation. The soil from settlement and plantation area are able to adsorb and retain the heavy metals at the surface, making it more suitable to use the ferronickel slag as compaction material for road construction than the soil from harbor area.