Experiment Study On Gas-based Shaft Furnace Direct Reduction And Melting Separation Of Hongge Vanadium-titanium Magnetite

In addition to rich in iron resources,Hongge vanadium-titanium magnetite is also associated with valuable strategic resources,such as vanadium,titanium,chromium and so on.However,the comprehensive utilization rate of the current blast furnace smelting process is low,which causes serious waste of resources and environmental pollution.Therefore,this article start from gas-based shaft furnace direct reduction and melting separation,the influence of reduction temperature and reduction atmosphere on the reduction behavior of Hongge vanadium-titanium magnetite were studied systematically,the reduction kinetics was also calculated;During the melting separation process,the influence of melting temperature,melting time and CaO/SiO2 ratio on the melting separation of slag and iron was investigated.The main conclusions are as follows:(1)The reduction rate,final reduction degree and reduction swelling increased with theincrease of reduction temperature;When the reduction atmosphere changed from DPCG to HYL-?,the reduction rate and the final reduction degree increased,and the reduction swelling decreased.In the whole reduction process,the reduction swelling increased at first and decreased later and stabilized at last.(2)When the reduction temperature was 900?,the reduction atmosphere had little effect on the phase composition and morphology of the reduced pellets.However,when the content of H2 increased,the area of the metal iron phase increased at 1050?.During the whole reduction process,when the reduction time increased,the metallic iron grains gradually increased,the large holes in the pellets became tiny pores.Then the metallic iron grains constantly aggregated and grew,the inner pores of the pellets reduced,and the iron phase gradually aggregated into the area of the sheet.At the end of the reduction,the slag phase was separated from the iron phase and formed two distinct regions.(3)The reduction of Hongge vanadium-titanium magnetite oxidized pellets was mainly controlled by the interfacial chemical reaction in the early stage.With the further development of reduction,the proportion of internal diffusion resistance increased.In the later stage of reduction,it was mainly controlled by internal diffusion and interfacial chemical reaction.The relationships between chemical reaction rate constant and temperature were:DPCG:Early stage:k=1.23exp(-52480/8.314T)Later stage:k=0.17exp(-32850/8.314T)WCSG:Early stage:k=2.12exp(-56770/8.314T)Later stage:k=0.21exp(-33260/8.314T)Midrex:Early stage:k=4.32exp(-61480/8.314T)Later stage:k=0.35exp(-37160/8.314T)HYL-?:Early stage:k=5.53exp(-62150/8.314T)Later stage:k=0.48exp(-39570/8.314T)(4)The recovery rates of iron,vanadium and chromium and the content of TiO2 in the slag increased firstly and decreased later with increasing melting separation temperature.It increased at the beginning and stabilized later with increasing melting separation time and CaO/SiO2 ratio.The rational melting separation parameters were:the melting temperature 1580?,the melting time 30 min,CaO/SiO2 ratio 0.6.The recovery rates of iron,vanadium and chromium were 97.91%,96.71%and 97.8%,respectively.The recovery rate of TiO2 and the content of TiO2 were 89.82%and 39.78%,respectively.