Atmospheric acid leaching of nickel laterites review: Part I. Sulphuric acid technologies

This review examines the atmospheric leaching (AL) of nickel laterite ores with sulphuric acid, specifically the limonite, smectite (clay) and saprolite fractions. The kinetics and mechanism of leaching of the key minerals are reviewed together with methods for enhancing nickel recovery. Existing and developing AL processes for extracting nickel and cobalt from these ores are then considered with comparison to high pressure acid leaching (HPAL) technology. This review also provides an overview of the emerging hybrid HPAL/AL and heap leaching technologies.