| Bayan Obo ores in Inner Mongolia of China is the famous RE,Fe,Nb,Ti and other important elements complex ore in the world.However,a variety of metal co-existence of the special nature still limits comprehensive recovery and utilization.How to realize the deep separation becomes the key to solve the problem of comprehensive utilization of tailings resources in Bayan Obo.In this paper,the thermodynamic conditions for the selective reduction of metal oxides in niobium tailings at different temperatures and reductants,as well as the behavior of migration,separation,enrichment such as Fe,Nb,Ti and RE elements were studied by thermodynamic analysis,compositional analysis and phase analysis.Under the experimental conditions,the following conclusions can be drawn:(1)The selective reduction of iron oxides in the niobium tailings of Bayan Obo and its preliminary separation from other minerals can be realized by using carbothermic reduction calcination and magnetic separation.The increase in calcination temperature favored the separation of iron,but at 1150?,the carbonaceous pellets begin to melt,localized slag and NbC formation around the metallic iron phase.(2)After carbothermic reduction at 1500?,the pyrochlore phase decomposed,and niobium oxides were partially reduced to NbC.NbC adhered to the iron droplets and dissolves.During the polymerization and settling of iron droplets in the slag,NbC gathered at the surface of slag and iron.With the formation of a small amount of TiC production,rare earth oxides did not occur reduction.By controlling the amount of carbon,NbC can be reduced and most of the niobium and all of the titanium and rare earths were enriched in the chalcopyrite phase,TiAlO3 phase and matrix phase.(3)The selective reduction of iron oxides and niobium oxides in niobium concentrates can be realized by using silicon as the reductant,and the alloy with niobium grade above 10%and rare earth rich residue containing titanium were obtained by smelting. |
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