Comparative study of limonitic and saprolitic laterite ores on the leaching characteristics under atmospheric pressure

Abstract

Sulfuric acid leaching as a function of acid dosage (200-800 kg H2SO4/dmt) and time (1-168 h) was performed on saprolitic laterite ores (SL) and limonitic laterite ores (LL) from different regions to characterize and compare the leaching behavior of saprolitic and limonitic laterite ores at room temperature and atmospheric pressure. The major mineral of SL is antigorite/lizardite, whereas the main minerals of LL are goethite and talc. The metal leaching efficiency of both SL and LL increased with rising acid dosage, and leaching behavior was related to acid consumption. The nickel leaching efficiency and rate constant of SL were higher than that of LL under the same acid dosage condition. XRD analysis on the residue after leaching confirmed that serpentine is easier to leach than goethite and talc due to the mineral structure. Kinetic analyses showed that the leaching of laterite ores employed in the present work was well fitted to the Shrinking Core Model with the rate-determining step of a solid product layer diffusion.