Selective Reduction Process of Low-Grade Laterite Nickel Ore with Reductants

Three types of reductants were selected to research their influence on selective reduction process of a low-grade laterite-nickel ore. The results showed that under the same reductants dosage, the selective reduction effect sequence was lignite>bituminite>coke. And, at the same fixed carbon amount (6% of lignite or 3% of coke), when 6% of lignite was used as a reductant, the selective reducing effect was better. Through X-ray diffraction (XRD), scanning electron microscope-energy dispersive spectroscope (SEM-EDS), and the reactivity of the reductants, it was important to guarantee weak reducing atmosphere namely low dosage of the reductant dosage for the selective reduction process. In the weak reducing atmosphere and at the same fixed carbon amount, selecting the reductant whose ash was low silicon-containing and high calcium-containing andiron-containing was beneficial to selective reduction. While due to that the dosage of reductant was low, the small amount of ash brought from the reductants only had a little effect on the whole roasting system. In addition, a type of a reductant with high reactivity was conductive to selective reduction, as it could be subjected to violent gasification reaction at the initial stage of the reaction and the reduction of the easily-reduced nickel oxide was facilitated. With lignite as the reductant and at its dosage of 6%, a ferronickel product with nickel grade of 3.99% and nickel recovery rate of 92.79% was obtained. © Editorial Office of Chinese Journal of Rare Metals. All right reserved.