Abstract
Rising demand for high-nickel cathode active materials has strengthened interest in alternative nickel sources that can support sustainable and scalable production. Ferronickel, traditionally used in the stainless-steel industry, is a promising feedstock for battery-grade nickel when efficiently converted via hydrometallurgical routes. This study investigates atmospheric leaching as an energy-efficient, lower-carbon method for extracting nickel from ferronickel to produce precursors for next-generation Ni-rich cathode materials. The work evaluates how solution composition, temperature, redox conditions, and mineralogical characteristics affect the dissolution of nickel and the precipitation of impurities under ambient-pressure conditions. Attention is given to achieving efficient removal of contaminants, particularly iron (Fe), via selective precipitation to produce battery-grade nickel sulphate. Integrated characterisation of leach residues and leachates provides insight into reaction mechanisms and the evolution of metal speciation. The results demonstrate that optimised atmospheric leaching of ferronickel can deliver chemically controlled intermediate solutions that meet the stringent purity and stoichiometric requirements for high-performance Ni-rich cathode precursor synthesis, offering a sustainable complementary route to conventional sulfide or laterite processing.