8th International Congress on Science and Technology of Ironmaking - ICSTI 2018

Limonitic laterite is an iron ore consisting of a mixture of hydrated iron oxide-hydroxides in varying composition. The generic formula of limonitic laterite is expressed as (Fe, Ni, Mg)O∙(OH)∙H2O. It is possible to obtain high quality ferronickel and iron oxide, which can be used as a blast furnace charge, through selective reduction of Ni using reduction potential difference between Fe and Ni in limonitic laterite. It is reported that the improvement of the quality of ferronickel and iron oxide extracted from limonitic laterite is controlled by optimization of the selective reduction of Ni in NiFe2O4 mineral formed during calcination. In this study, the optimized reduction condition for the selective reduction of Ni in NiFe2O4 is thermodynamically derived, and the effect of oxygen partial pressure and temperature on the grade of ferronickel and iron oxide is evaluated. The NiFe2O4 mineral used in this experiment was synthesized by physical mixing of NiO and Fe2O3 powder, followed by calcining at 1200℃ for 24 hours in an air atmosphere. The reduction behavior of the synthesized NiFe2O4 is analyzed by TGA and XRD. As a result of the selective reduction of Ni in NiFe2O4, it is confirmed that the ferronickel and iron oxide (magnetite, wustite) are formed in experimental conditions. Using bromine-methanol leaching method, the composition of ferronickel in leaching solution is quantitatively analyzed by ICO-OES analysis, and the equilibrium phase of coexisting iron oxide was analyzed by XRD.