Metallurgical Beneficiation of Iron Laterite Ores with the Formation of a Metallic Nickel–Cobalt Concentrate

Abstract

A new process is developed for metallurgical beneficiation of iron laterite nickel-containing (limonite) ores with the formation of a metallic nickel–cobalt concentrate. This process includes reducing roasting of the ores with sulfur-containing additions in the temperature range 1100–1200°C, the fragmentation of the roasting product, and the magnetic separation of metallic and slag phases. The coarsening of metallic particles in roasting is shown to occur with the participation of a low-melting-point phase (iron oxysulfide Fe(O,S)). In this case, nickel and cobalt concentrate in a metallic phase in the form of an alloy with iron (ferronickel). At the optimum charge composition and reducing roasting parameters, ferronickel particles coalesce and grow to 40–100 μm, which creates favorable conditions for the subsequent beneficiation of the roasting product (cinder) by magnetic separation. After wet magnetic separation of a fragmented cinder, the extraction of nickel and cobalt into a magnetic fraction is 92 and 84%, respectively. When a poor limonite ore (1.03% Ni, 0.05% Co) is processed according to the developed technology, the synthesized metallic concentrate contains up to 8.3% Ni and 0.37% Co.