Enrichment of nickel and iron from nickel laterite ore/coal composite pellets by deep reduction and magnetic separation

Iron and nickel minerals in a nickel laterite ore were deeply reduced to metallic iron and nickel, and then they were magnetic-separated for the enrichment of an iron-nickel concentrate. The reductive roasting parameters were optimized and the optimal conditions are obtained as the C/O atomic ratio of 1.3, the reduction time of 80 min, the CaO content of 10%, and the reduction temperature of 1 300℃. Under these optimal conditions, the grades of nickel and total iron in the iron-nickel concentrate are 5. 17% and 65.38%, and the recovery rates of nickel and iron are 89.29% and 91.06%, respectively. The deeply reduced ore and the magnetic separated concentrate were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive Xray spectrometer (EDS). The results show that metal particles of ferro-nickel are found in the reduced ore. Nickel is dissolved in ferronickel, and a little portion of iron exists as FeO. A large amount of gangue is removed by magnetic separation, and the concentrate contains iron, ferro-nickel, FeO, and little CaO·MgO·2SiO₂.