Extraction of a nickel-iron alloy from nickel laterite ore through selective reduction and smelting process

Metallization pellets were prepared from silicon-magnesium-type nickel laterite ore through metallization roasting and smelting process. Orthogonal experiment was carried out to investigate the effect of control parameters on the experimental results. A nickel-iron alloy was extracted from the metallization pellets after 30 min of smelting at 1 500℃. It is shown that C/O molar ratio has prior influence on the selective reduction process, followed by roasting temperature, roasting time and basicity. The nickel grade of the nickel iron alloy can be controlled at 19% in the extraction process by governing the manipulated factors. The sulphur and phosphorus distribution ratio increases when the basicity increases from 0.8 to 1.2. The metallization pellets and slag were microscopically analyzed by X-ray diffraction and scanning electron microscopy. The results show that the added limestone reacts rapidly with the complex ore to produce nickel oxide and iron oxide, and thus, promotes the reduction rate. When the amount of limestone is insufficient, little amount of iron in the form of hematite exists in the metallization pellets which have the metallization rate of 70%.