The reduction behaviour of iron from low grade nickel laterite ore using a solid state deoxidisation method

Abstract

The reduction behaviour of iron from low grade nickel laterite ore using a solid state deoxidisation method was investigated. The results showed that the α_FeO was strongly influenced by the reaction temperature in both gas–solid and solid–solid reduction processes, and a higher temperature was more favourable for iron reduction, but the conversion percentage decreased when a gaseous reductant was used at 850°C because of phase transformation. The conversion percentage of Fe₂O₃ to FeO first increased and then decreased with increasing reduction time. Because the reduction mechanism of nickel laterite ore is indirect, a higher α_FeO (>75%) can be obtained by increasing CO and carbon content. In the gas–solid reduction process, a smaller particle size was beneficial to iron reduction. In the solid–solid reduction process, the conversion percentage first increased and then decreased with increasing CaO content. In both reduction processes, forsterite was found by XRD in the reduced ore, and the peak intensity of forsterite increased with increasing reduction temperature. SEM revealed that the nickel laterite ore was transformed from large granular and sandwich structures to small granular and flocculent structures during the reduction process.