Research On The Process And Mechanism Of Vanadium Decarburization From Stone Coal

Vanadium is an important strategic materials,it’s widely used in steel industry,national defense,chemical industry,textile industry and so on.The resource of Vanadium ores in China are mainly composed of vanadium titano-magnetite and stone coal,but only stone coal worth mining.The conventional technical level of extraction of vanadium processes didn’t consider using carbon,and had high cost,low recovery of vanadium,pollution and other shortcomings generally.This paper studies on the utilization of carbon resources,at the same time,consider the leaching rate of vanadium,in order to achieve the purpose of comprehensive utilization of stone coal.And research on the theory of decarburization process through SEM and XRD base on previous research,the main research contents and results are as follows:1.The thermodynamic calculation of decarburization processThere are reactions as the carbonaceous materials oxidation,the vanadium oxidation,the pyrite oxidation,the calcite decomposition in decarburization process.By calculating the Gibbs free energy,drawing the Gibbs free energy-temperature diagram.The results shows that: the reaction of carbonaceous materials oxidation at first,then the reaction of pyrite oxidation in decarburization process,their existing inhibite vanadium oxidation.The order of vanadium oxidation is trivalent vanadium oxidized to tetravalent vanadium first,then tetravalent vanadium toxidized to pentavalent vanadium.2.The study on process mineralogyThe analysis of Chemical composition,vanadium valence and vanadium phase.Analyzing the exist form of quartz,calcite,carbide,roscoelite,illite hydromica and pyrite through backscattered electron image.The results shows that: the carrier of vanadium ores are very fine and with other minerals cements closely,and the carbon inlaided as pollutant.It is difficult to effective recovery with mineral processing,only metallurgy way.3.The vanadium oxidation trend,surface and phase changes of mineralThe efficiency of decarburization and vanadium oxidation of stone coal are connected with temperature,time,particle size and air volume.Through a series of experiments,the results shows that: when the temperature is higher than 900℃ or when the temperature is 800℃ and decarburization time is longer than 20 min,the sintering phenomenon appear,the leaching rate decline;the reaction of carbonaceous materials oxidation and pyrite oxidation at first in decarburization process.The optimal condition of decarburization is 800℃,15 min,-100 mesh,1.2 times of air volume,the vanadium conversion rate reachs 43.75%,direct leaching rate is 72.15%.4.The calculation of vanadium oxidation kineticsThe reaction of vanadium oxidation belongs to gas-solid reaction;the kinetic model is non shrinking core reaction model.Based on the isothermal oxidation curves under different temperatures,obtain that the oxidation process of vanadium belongs to the inner diffusion model,and achieve the slope k of the line.Through the Arrhenius formula obtaine the apparent activation energy E=15.35 k J/mol.