Early-stage temperature-dependent leaching kinetics and mechanisms of saprolitic and limonitic nickel laterite ores under atmospheric conditions

Abstract

This study investigates the early-stage leaching behavior and temperature-dependent kinetics of saprolitic laterite (SL) and limonitic laterite (LL) ores under atmospheric acid leaching conditions at various temperatures to capture early-stage dissolution of nickel, magnesium, and iron. Both ores exhibited temperature-dependent increases in metal extraction, with highest extractions observed at 45 °C for saprolitic laterite ore and 65 °C for limonitic laterite ore. Structural analysis of leach residues revealed that the highest extractions corresponded to progressive collapse of key minerals—lizardite in saprolitic laterite ore and goethite and clinochlore in limonitic laterite ore. Kinetic analysis using a shrinking core model showed that solid product layer diffusion was the dominant rate-limiting step for all metals in both ores. Activation energies exceeding 56 kJ/mol for all metals suggested diffusion resistances, likely due to the formation of silica-rich product layers. This study clarifies the mineral leach mechanisms governing early-stage leaching in saprolitic laterite and limonitic laterite ores and provide a basis for optimizing selective nickel leaching. © 2026 Elsevier Ltd.