Ni Recovery from Nickeliferous Pyrrhotite Concentrates via a Thermal Concentration Process: Effects of Heat Treatment Time

Abstract

Nickeliferous pyrrhotite (Pyrr) tailings represent a promising Ni resource. Previous work has demonstrated that heating of nickeliferous Pyrr in the presence of suitable additives under a non-oxidizing atmosphere is capable of recovering the Ni value in the form of ferronickel alloy . In this study, the Pyrr concentrate, a flotation product of nickeliferous Pyrr tailings , was thoroughly mixed with metallic Fe and activated carbon, and then pressed into briquettes. The resultant briquettes were heat-treated at 900 °C for varying periods of time in Ar, followed by an Ar-quenching operation to retain the high-temperature structure. The calcine microstructure was examined as a function of treatment time, together with the composition of Ni-bearing phases. It was shown that progression of the iron sulfidization was companied by the formation of ferronickel alloy via multiple mechanisms, and prolonged treatment time promoted the uniformity of phase compositions and coarsening of the alloy particles.