Comparative atmospheric leaching characteristics of scandium in two different types of laterite nickel ore from Indonesia

Abstract Atmospheric acid leaching behaviour of scandium (Sc) in two different types of laterite nickel ore from Indonesia was investigated. Ore and leaching residue characterization was performed by XRD, FTIR, XPS, and SEM-EDX. Ore characterisation showed that the major minerals in limonitic laterite were goethite, magnetite, hematite, and saprolitic laterite mainly consisted of goethite, magnetite, lizardite, clinochlore. Sc in two different types of laterite nickel ore are distributed widely among minerals, but it mainly hosts in Al-bearing goethite and silicate minerals. Sc host minerals in limonitic and saprolitic laterite nickel ore are different. 84.27% and 59.86% of Sc in limonitic and saprolitic laterite could be leached under the experimental conditions of 3 mol/L H2SO4, 80℃ reaction temperature, leaching duration 3 h and liquid to solid ratio 6:1, respectively. The results show that Sc and Mn, Mg in limonitic laterite have similar dissolution characteristics because the extractions of Sc and Mn, Mg are linearly correlated. Sc in limonitic laterite is susceptible to acid attack and easier to be extracted than other metals except for Mn. Sc and Ni in saprolitic laterite have similar dissolution characteristics because Sc is not strongly related to metals other than Ni. Sc in saprolitic laterite is more difficult to extract than Mg and Ni, but it is easier to be leached than other metals. The dissolution kinetics was found to fit well to the shrinking core model with the diffusion through the product layer as the rate controlling step. Results of this research may assist in the development of a more efficient process for exacting Sc from laterite nickel ores.