Coupled Mechanism Of Vanadium,Titanium And Chromium On The Kinetics Of Oxidation Roasting-Gas Based Reduction Of High-chromium Vanadium-Titanium Magnetite

High-chromium vanadium-titanium magnetite has large reserves and is of great value for comprehensive utilization.Titanium,vanadium and chromium are three important valuable and characteristic components of high-chromium vanadium-titanium magnetite,and are recognized as strategic resources worldwide.The influence of titanium,vanadium and chromium on the oxidative roasting and gas-based reduction of high-chromium vanadium-titanium magnetite is of great significance.Based on the summary and review of previous studies,this experiment investigated the coupling mechanism of single and multiple elements of titanium,vanadium and chromium on the kinetics of pellet oxidative roasting and gas-based reduction,focusing on the change pattern and reasons for the influence of valuable elements on the activation energy of pellet reaction,and further investigated the changes of the reaction mechanism and limiting links of oxidation and reduction processes;created a mathematical model of valuable elements and activation energy of reaction In addition,we also analyzed the changes in the composition and mineral structure of the pellets by microscopic analysis.The following conclusions are drawn.（1）TiO₂ will inhibit the oxidation process of pellets,Cr₂O₃ and V₂O₅ both promote the pellet oxidation reaction,with the strongest promotion effect of Cr₂O₃.the limiting link of the oxidation process of Cr₂O₃ pellet stage I is consistent with the phase boundary reaction control,and the rest of the single component materials are diffusion controlled.（2）TiO₂ & V₂O₅ two-component coupling further inhibits the pellet oxidation process.5% TiO₂ & V₂O₅ pellet oxidation process limiting link is chemical reaction control,the rest of two-component pellets are in line with diffusion control.three component pellets TiO₂ & V₂O₅ & Cr₂O₃ oxidation activation energy is higher than the reference pellet,lower than TiO₂ & V₂O₅two-component pellets.5% TiO₂ & 1% V₂O₅ & Cr₂O₃ pellets oxidation process limiting link is consistent with phase boundary reaction control,the remaining three component materials are consistent with diffusion control.（3）TiO₂,V₂O₅ and Cr₂O₃ form FeTiO₃,FeCr₂O₄ and FeV₂O₄ refractory phases embedded in metallic iron phase in reduced pellets,respectively,with increased activation energy for reduction and single unfavorable pellet reduction,with Cr₂O₃ inhibiting pellet reduction with the greatest effect;TiO₂ pellet phaseⅡ limiting link is consistent with random nucleation and subsequent growth,V₂O₅ phase Ⅱ is a phase boundary reaction,and the remaining single elements are diffusion controlled.（4）The degree of deterioration of the pellet reduction process further deepens when TiO₂ & V₂O₅ two-component elements are coupled.10% TiO₂ &V₂O₅ pellets stage I limiting link is consistent with random nucleation and subsequent growth,while the rest of the two-component pellets are diffusioncontrolled.the TiO₂ & V₂O₅ & Cr₂O₃ three-component pellet reduction activation energy is higher than that of TiO₂ & V₂O₅ two-component pellets,and The reduction activation energy of 12.5% TiO₂ & 0.50% V₂O₅ & Cr₂O₃ pellets are higher than that of 5.00% TiO₂ & 1.00% V₂O₅ & Cr₂O₃ pellets.The limiting links of the reduction process of the three component materials are all consistent with diffusion control.