Phase transformation of nickel laterite ores in the selective reduction roasting process

Since it is difficult to extract nickel from laterite ores with low nickel grade by traditional beneficiating methods, the microstructure and phase transformation of a nickel laterite ore with the nickel grade of 1.49% were investigated by using a selective reduction roasting method at different roasting temperatures and time. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) results show that after selective reduction roasting at different roasting temperatures and time, nickel-ferrous minerals in the nickel laterite ore are reduced to ferronickel gradually, while ferrous minerals are mainly transformed to wustite. Silicate nfinerals exist in the formation of olivine in the roasted ore. Reduction roasting and magnetic separation experiments illustrate that when the nickel laterite ore with the addition of 7% NCS as the additive and 2% soft coal as the reductant roasts for 50 min at 1200℃, the ferronickel product obtained from magnetic separation has the nickel grade of 9.78% with the nickel recovery of 92.06%, and the recovery difference of nickel and iron is 62.51%. The experimental result indicates that nickel-ferrous and ferrous minerals were reduced selectively.