Study On Direct Reduction-grinding Process Of Low-grade Vanadium-titanium Magnetite Concentrate

The major strategic resource of vanadium-bearing titanomagnetite with 40 billion tons in china,a kind of mineral resources including iron,vanadium,titanium and other metals,possess very high comprehensive utilization value.With the reduction of China's high-quality vanadium-bearing titanomagnetite resources,the dependence on foreign countries increased year by year.It has significant meaning to strengthen the efficient,clean and comprehensive development of ultra-lean vanadium and titanium magnetite resources to improve China's resources and promote the sustainable development of vanadium and titanium industry.The current research has focused on the comprehensive development and utilization of high grade vanadium-titanium magnetite or high-chromium vanadium-titanium magnetite.There are few reports on the comprehensive development and utilization of ultra-lean vanadium and titanium magnetite,due to the high content of vanadium and titanium,the low grade vanadium-bearing titanomagnetite has high comprehensive utilization value.In this paper,the low grade vanadium-bearing titanomagnetite concentrate after ore dressed was used as raw materials,In the process of selective reduction of titanium magnetite,system to carry out a low-grade vanadium-titanium magnetite direct reduction,enhanced reduction process,strengthening grinding separation study,achieve the low-grade vanadium-titanium magnetite concentrate in the iron and vanadium/titanium efficient separation and achieved the following innovative results:(1)The reduction behavior of iron vanadium and titanium in the process of direct reduction of low grade vanadium-titanium magnetite was systematically studied.The migration regularities of iron vanadium and titanium were obtained.The results show that the vanadium in the low grade vanadium-titanium magnetite concentrate would not be reduced by controlling the molar ratio of carbon to iron and the reduction temperature.Furthermore,the vanadium and titanium in the selective direct reduction process are studied.The results show that the molar ratio of carbon to iron is 1.2,the reduction temperature is 1200°C and the holding time is 120min.The addition of additive can make the metallization ratio of low grade vanadium-titanium magnetite reach 91.3%.The recovery of Fe,V,Ti can reache 96.2%?85.4%?88.6%respectively.The cooling process can enhance 39.5%of sulfur reduced from the final product.(2)The study of growth process of iron particles during the selective reduction shows that the increase of reduction temperature can promote the growth of iron particles during the direct reduction process,but the excessive temperature is not conducive to the separation of the iron and vanadium.The most suitable reduction temperature is 1200?.Sodium salt can destroy the structure of fayalite and iron spinel,generate low-melting-point products,and improve the diffusion of iron atoms in complicated phases,which can finally result in larger iron particles.With the help of different anions in composite additives,the effect of promoting the growth of iron particles is more obvious than that of the single sodium salt additive.(3)The effect of grinding fineness and magnetic field strength on the recovery of Fe,vanadium and titanium was deeply explored.It was found that with the increase of grinding time the particle size became more and more fine and the recovery rate did not increase with the increase of particle size.The most suitable grinding time is 30min with the particle size of 14?m,the magnetic field strength of 100mT.Finally,the recovery rate of iron is 94.67%and the grade is 97.31%.