Studies On Reduction Behavior In Microwave Field And Magnetic Separation Of High-chromium Vanadium Titano-magnetite

The high chromium vanadium-titanium magnetite is a kind of rich resource of China. According to some researches, the total amount of the resource is about36tons. Because of the existing technology has a very low utilization rate of the mineral resources, it has not been industrialized development to realize the comprehensive utilization of the mine. Hence the development of a consistent with the characteristics of resources, effectively improve the valuable component separation and utilization rate of the new method is the current urgent subject. In this paper, the high chromium vanadium titanium magnetite microwave thermal reduction was systemically studied by thermodynamic principles, chemical analysis, phase analysis and SEM analysis, and using those methods process parameters can be optimized. After the reduction experience, use the magnetic to separate the reduction product, totally understand the iron, vanadium, titanium and chromium migration rule. On this basis, optimize the process parameters for the comprehensive utilization of resources of vanadium-titanium magnetite new technology and new technology to provide a theoretical basis. The conclusions show as following:(1) By studying the influence of C/O, forming pressure, microwave heating power, reduction temperature and reduction time on the metallization of reduction products, the optimum parameters of the experiment are obtained as follows:forming pressure is30MPa, C/O is2.0, the reduction temperature is1300℃, reduction time is30min and using the N2to protect the cooling period. Under the conditions, the metallization rate of reduction product reached93.83%.(2) Additives to improve the activity of FeO, reducing the difficulty of reduction, the Fe2+â†'Fe enhanced reduction process is conducive to the formation and growth of crystal grains of iron, so that the rate of reduction of the metal product significantly enhance, improve the maximum amplitude reached nearly30%. Under the conditions of1150℃and reducting for30min, the reduction of metal product rate is improved and the proportion of increasing is18-36percentage. With CaF2as the additive, under1250℃reducing30min the metallization rate was93.32%; Using the borax as the additive, under1250℃reducing20min the metallization rate was 73.75%; With the boron oxide as the additive, under1250℃reducing20min the metallization rate was94.78; Using the CaF2-borax as the additive, under1200℃30min the metallization rate was82.37%, with CaF2-boron oxide as the additive,1250℃reducing20min the metallization rate was85.60%;(3) Using the CaF2as the additive, the magnetite reduction process is Fe3O4â†'Ca0.15Fe2.85O4â†'Fe. Using the boron compounds as the additive, the efficiency compound is CaO, B2O3, it can interact with the minerals magnetite and ilmenite. As a result, it can generate Ca0.15Fe2.85O4and perovskite intermediate products. What is more, the reduction product can promote the reduction of metal iron, and the reducing product is mainly metal iron, magnesium, vanadium perovskite, spinel containing iron titanium ore and Ca0.15Fe2.85O4.(4) The strength of the magnetic field has some effect on magnetic materials, magnetic properties and iron recovery rate. The magnetic iron grade of the product was above73%, iron recovery rate was more than90%and the optimum magnetic field strength is180kA/m. And at this time the iron grade is76.16%, recovery rate of iron is93.58%;58.96%n of vanadium was distributed in magnetic phase, the last42.83%was distributed in the nonmagnetic phase;49.62%of Ti was distributed in magnetic phase, and the remaining52.28%was distributed in the nonmagnetic phase;72.18%of Cr was distributed in magnetic phase, and the rest27.82%was distributed in the nonmagnetic phase. After the magnetic separation, the magnetic material was maining constitute by iron phase, TiN and a small amount of titanium iron, this was because of the solid solution of TiN and Fe to generate the magnetic non-magnetic phase. The nonmagnetic phase was mainly consisted by MgO and FeO solid solutions [(MgO)0.593(FeO)0.407], titanium magnesium spinel (MgTiO5) and V (magnesium spinel MgV2O4).