关键词: 褐铁矿, 真空焙烧, 碳热还原, 钙质添加剂

Abstract: The effects of CaF₂ on the phase of product from vacuum carbothermal reduction of limonitic laterite ore at vacuum conditions were studied. XRD， SEM/EDS and chemical analysis methods were used to analysis the phases of roasting product and the Fe-Ni rich residue. The roasting results indicated that there were significant influence on the roasting results under pressures ranging from 10 to 50 Pa whether the raw materials melted(roasting temperature)， the content of Ni and Fe in the unmelted phase only reached 1.84% and 53.10%， respectively； nonetheless， on the melted materials， the content of Ni in the NiFe2O4 reached 67.35% and the content of Fe in the Fe2O3 reached 75.16%. The thermodynamic analysis and reduction results indicated that CaF₂ reacted with Fe and Ni in the raw materials to form FeF₂， FeF₃， NiF₂ and other low melting point eutectic to promote material melting and accelerate the mass transfer and heat transfer of the reactants， and effectively promote the agglomeration of Ni and Fe， in addition， the presence of CaF₂ had no significant effect on the phase of roasting product duringthe vacuum carbothermal reduction of limonite； the optimum reduction conditions of limonite type laterite nickel ore were 1 450 ℃ and 5% dosage of CaF₂. The recovery rates of Ni and Fe after reduction were 99.05% and 88.23%， respectively.

Key words: Limonite, Vacuum roasting, Carbothermal reduction, Calcium additive