Influence of Sodium Thiosulfate in the Process of Reduction Roasting and Magnetic Separation for Nickel Laterite Ore

The experiment chooses sodium thiosulfate as an additive in the process of the reduction roasting-magnetic separation for nickel laterite ore.The study finds that the additive plays the role of both alkali metal salt and sulfuration.In the process of roasting,the alkali metal ion replaces nickel ion in silicate phase,and the sulfur forms Fe-Ni-S phase with iron oxide in reduction stage at high temperature.The enrichment of ferronickel in the form of liquid and the formation of no magnetic FeS,which is abandoned easily in the subsequent magnetic separation,make the separation of nickel achievable.In this paper,the conditions of reduction roasting and magnetic separation technology were also investigated.The experimental results show that the content and recovery of nickel increase to 7.62% and 64.83% from the original 2.58% and41.66%,respectively,under the best condition of reduction temperature 1 100℃,reduction time60 min,the ratio of reducing gas volume V(CO)/V(CO2)8/2,the mass fraction of additive20%,the intensity of magnetic field 0.15 T,and grinding time 1.0min.The result of nickel-iron recovery difference of 47.10% arrive the goal of the nickel enrichment and separation for nickel laterite ore.