| As is known to all, vanadium, titanium and chromium are important strategic resources in the world, which are the important materials guarantee for national economic development and national security, and are widely used in metallurgy chemical, aerospace, national defense military and other fields. The high chromium vanadium-titanium magnetite in Panxi of China is not only rich in iron, but also it contains the valuable elements such as vanadium, titanium and chromium. Due to its complex mineral composition and special material characteristics compared with ordinary vanadium-titanium magnetite, the comprehensive utilization of iron, vanadium, titanium and chromium is low in the process of the blast furnace, and it causes serious resource waste and environmental pollution.Based on the present research and utilization situation of high chromium vanadium-titanium magnetite, firstly, beginning with the basis characteristics of high chromium vanadium-titanium magnetite, this thesis researches the influence of roasting temperature and roasting time on high chromium vanadium-titanium magnetite oxidation process, and confirms the reasonable process parameters of high chromium vanadium-titanium magnetite pellets roasting. Through the gas-based shaft furnace direct reduction experiments, this study inspects the influence of reduction temperature and reduction atmosphere condition on high chromium vanadium-titanium magnetite pellets reduction process, and analyzes the pellets reduction phase process and the shaft furnace reduction kinetics. By melting separation experiments, the study analyzes the quality of high titanium slag and vanadium-chromium-bearing iron after the melting separation.Through this study, several conclusions are obtained as follows:(1) The high chromium vanadium-titanium magnetite is mainly composed of magnetite, chromite, titanomagnetite, couisonite and so on, and its particle size is coarse, and the proportion of particle size below 0.074 mm is only 29.98%;(2) By improving the roasting temperature and prolonging the roasting time, the high chromium vanadium-titanium magnetite pellets compression strength can be improved. The reasonable roasting temperature is 1300℃ and the roasting time is 20 min;(3) The phase change of the high chromium vanadium-titanium magnetite pellets during the oxidation process is: Fe3O4â†'Fe2O3ï¼› Fe2.75Ti0.25O4â†'Fe9TiO15+FeTiO3â†'Fe9TiO15+Fe2Ti3O9ï¼› FeV2O4â†'(Cr0.15V0.85)2O3: FeCr2O4â†'Cr1.3Fe0.7O3+(Cr0.15V0.85)2O3:(4) As the reduction temperature and the content of H2 in the reducing atmosphere increases, the reduction degree of high chromium vanadium-titanium magnetite pellets increases. In the condition of reduction temperature 1100℃, the H2:CO=5:2, and the reduction time 30 min, the reductive degree can reach 95%. Reduction is controlled by the interfacial chemical reaction and internal diffusion in initial stage, and the interfacial chemical reaction is dominant; With the reduction, the internal diffusion becomes restrictive link, and gradually dominates;(5) The gas-based direct reduction process of the high chromium vanadium-titanium magnetite is: Fe2O3â†'Fe3O4â†'FeOâ†'Feï¼› Fe9TiO15+Fe2Ti3O9â†'Fe2.75Ti0.25O4â†'FeTiO3Oâ†'TiO2; (Cr0.15V0.85)2O3â†'FeV2O4;Cr1.3Fe0.7O3â†'FeCr2O4ï¼›(6) By electric furnace melting separation of reduction product, slag with high content titanium and vanadium-chromium-bearing iron are obtained, and TiO2 grade in slag is 39.36% and its yield rate is 89.69%. TFe in iron is 92.34% and its yield rate reaches 93.53%; The yield rate of V is 85.68%; The yield rate of chromium reaches 89.50%. The process and conditions of smelting separation would be further studied. |
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