Study On The Improvement Of Vanadium Recovery Rate By Reduction-melting Separation Of Vanadium-titanium Ore In Xinjiang

Vanadium-titanium magnetite,as a multi-component mineral,takes iron,titanium and vanadium as its main valuable elements,accompanied by a part of chromium,gallium,scandium,cobalt,nickel,and platinum group elements,which is a mineral resource with great comprehensive utilization value in China.However,most of the vanadium-titanium magnetite proved in China are composite symbiotic minerals,and the grade of valuable elements is relatively low,which generally has the shortcomings of refractory ore and difficult separation.The difficulty of smelting vanadium titanium magnetite is mainly due to the inability to economically solve the problem of efficient separation of metal elements,and the high content of titanium dioxide in the slag makes the slag viscous,which affects the separation and fluidity of slag and iron.In this study,vanadium-titanium magnetite from Xinjiang Congling was used as raw material,and coke was used as reducing agent.The raw materials were tested and analyzed.The theoretical basis of thermodynamics and kinetics of vanadium-titanium magnetite reduction was studied.The effects of carbon content in pellets,roasting time and roasting temperature on the performance of internal carbon distribution were obtained.The effects of alkalinity,total carbon content and melting temperature on the reduction process of vanadium-titanium magnetite concentrate and the yield of vanadium element were obtained.The chemical composition of the final slag sample and iron sample was analyzed.The XRD and SEM-EDS analysis were carried out.The optimal experimental parameters of vanadium-titanium magnetite smelting in electric furnace were obtained and applied to semi-industrial tests.The following conclusions were obtained by analyzing the experimental results:（1）The thermodynamic and kinetic analysis of the reduction process of vanadium-titanium magnetite shows that in the temperature range of 1350 K to 1600 K,all kinds of oxides of Fe can be completely reduced to metal Fe.At this time,the oxides of Ti remain in the slag system,which realizes the separation of titanium and iron in theory.The carbothermal reduction reaction mechanism of V during reduction and melting of vanadium-titanium magnetite is mainly controlled by the diffusion process of（V₂O₅）→（V₂O₅）^S in slag phase and the diffusion process of[V]^S→[V]in molten iron.（2）The analysis of the metallization roasting experiment results of vanadium-titanium magnetite shows that higher internal carbon content and internal alkalinity are not conducive to improving the compressive strength and falling strength of the green ball.The carbon content in the pellets makes the metallization rate increase first and then decrease,but it is not conducive to increasing the compressive strength of the pellets.In summary,the optimum conditions of metallization roasting test are as follows:carbon content 10%,roasting temperature 1250°C,holding time to 60 mins,the metallization rate of pellets is 80.5%,and the compressive strength is 1573.6 N.（3）From the analysis of the reduction-melting test results of vanadium-titanium magnetite concentrate,it can be concluded that increasing the melting temperature and alkalinity makes the separation effect of vanadium-titanium magnetite slag iron better,and improves the enrichment effect of vanadium and titanium elements.However,too high reduction temperature and alkalinity are not conducive to the recovery of vanadium elements.With the increase of carbon content,the content and recovery rate of vanadium in molten iron increased first and then decreased.In order to achieve the maximum recovery rate of vanadium in molten iron,the optimum smelting parameters of vanadium-titanium magnetite should be:alkalinity 1.2,total carbon content 15%,reduction temperature 1500°C.Under this condition,the recovery rate of V reached98.07%.（4）According to the optimal process parameters of reduction-melting separation of vanadium-titanium magnetite in the laboratory,the expansion test was carried out.The results of semi-industrial test shows that the smelting atmosphere and time of the arc furnace,the ratio and shape of the coke and the alkalinity have an effect on the reduction-melting separation of vanadium-titanium magnetite and the yield of vanadium in the molten iron.The actual temperature in the DC electric arc furnace is too high to cause excessive oxidation of vanadium.The vanadium recovery rate obtained in the final test reached 74.88%...