| Since the 1960s in China has been carried out experimental study using vanadium oxide or direct alloying of vanadium slag smelting technology,compared to traditional ferrovanadium smelting vanadium steel,direct alloying technology the technological process is shortened,reducing energy consumption,reduce waste water,waste gas emissions and other advantages,is an important development of energy conservation and emission reduction,green metallurgy direction,The industrial test results of various steel mills also confirm the feasibility of direct alloying process.Based on experimental research and theoretical calculation,the effects of different conditions(type of reducing agent,basicity of pressing block,amount of reducing agent,reduction temperature)on the self-reduction behavior of vanadium slag were studied in this paper.On the basis of self-reduction,the direct alloying process of LF was simulated through a high-temperature tubular shaft furnace.The influences of the order of pressing block addition,alloying time,alloying temperature and slag amount on alloying effect were further investigated.The main conclusions are as follows:(1)Through the self-reduction experiment of vanadium slag containing aluminum ash pressing block,it can be concluded that:Under the conditions of Al/O molar ratio 0.67,basicity 1.0 and reduction temperature 1600℃ the reduction degree of oxides FeO,Cr2O3,MnO and V2O5 in slag is higher,which are 99.05%,81.94%,84.02%and 89.83%respectively.Excess addition of aluminum ash leads to a large amount of Al2O3,resulting in the precipitation of spinel phases(McAl2O4)and(CaAl4O7)from the slag,which has a great influence on the viscosity of the slag,the polymerization and deposition of metal droplets,and leads to a significant decrease in the reduction degree of oxides in vanadium slag.(2)Through the self-reduction experiment of vanadium slag containing carbon compacts,the results show that the reduction effect is better under the conditions of the C/O molar ratio of the compacts is 1.2,the basicity is 0.5,and the reduction temperature is 1600℃.The reduction degrees of the oxides FeO,Cr2O3,V2O5 and MnO in the slag are 97.21%,81.04%,80.72%and 75.64%,respectively.When the basicity is greater than 0.5,excessive CaO replaces FeO in FeTiO3,forming high melting point perovskite(CaTiO3)to precipitate slag phase,leading to the increase of liquid temperature of molten slag.(3)Based on the self-reduction of vanadium slag compactor,the direct alloying process of LF furnace was simulated through a high-temperature tubular shaft furnace.The results show that:The results show that the vanadium y ield is 36.36%,the vanadium increase in molten steel is 0.208%,and the alloying effect is only 43.34%of the results of the self-reduction experiment.The yield of vanadium is 84.54%when vanadium slag containing carbon pressed block is alloyed,and the alloying effect is similar to the result of self-reduction.Therefore,toner is selected as the direct alloying reducing agent of vanadium slag.(4)The direct alloying experiment was carried out in a high temperature tubular shaft furnace.The results show that the alloying reaction is a first order reaction,and the diffusion of V from slag steel boundary to molten steel is a limiting link.When the target vanadium increase rate is 0.65%,the alloying temperature is 1600℃,and the alloying time is 20 min,the alloying effect is better,the vanadium increase rate is 0.55%,and the vanadium yield is 84.54%.When alloying time is extended to 30 min,the vanadium increase increases to 0.56%,and the vanadium increase decreases with the increase of top slag content.When the target vanadium increase is 1.05%,the vanadium increase increases to 0.60%,but the vanadium recovery rate decreases to 57.79%. |
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