Preparation Of Vanadium By Electrolysis Of V₂O₃ Fluoride With La₂O₃

At present,the applications of rare high-meting point metals are more and more widely,but the problems in the industrial preparation,such as complex process,discontinuous production,and large pollution,limit the applications of high-melting point metals.Scholars at Cambridge University at the end of the last century developed solidstate cathode-melting electrolysis,a new process for continuous,low-cost preparation of high-melting-points metals.The technique has short flow,and little pollution and is universality.However,there are still some problems at present,such as low electrolytic efficiency,slow electrode oxidation rate,carbon pollution of cathode products,metal elements in cathode products,and molten salts forming alloys,etc.Therefore,this article uses ammonium vanadate more as raw material,after preforming,pyrolysis,hydrogen reduction,no carbon pollution resulting from the high-temperature sintering the electrical conductivity of the strong V2O3 as solid cathode,in the process of electrolysis in cryolite system as the supporting electrolyte deoxidization process,by adding lanthanum oxide strengthen deoxidization process,realize the fast solid metal vanadium carbon-free,greatly improving the current efficiency.The effects of decomposition process(temperature and time),reduction process(heating system,gas flow rate,reduction time,and reduction temperature)and sintering process(sintering temperature and time)on the preparation of V2O3 cathode are investigated.And the optimum technological conditions are determined.The results show that the optimal process conditions are as follows:decomposition temperature is 350℃,decomposition time is 120 min,The system is 1,the hydrogen flow is 0.2 L·min-1,the reduction time is 30 min,and the reduction temperature is 650℃.The best sintering temperature was 1250℃ and sintering time is 120 min,The carbon-free V2O3 cathode with vanadium content of 66.3%and porosity of 64.9%can be obtained.The kinetic process of hydrogen reduction to produce V2O3 is studied.The most probable non-isothermal kinetic mechanism function conforms to the one-dimensional diffusion model,and the kinetic equation is:dx/dt=7.42×10-4exp(-27.15/RT)1/2xWith graphite as anode and V2O3 as the cathode,high purity metal V is prepared by adding La2O3 electrode oxidation in cryolite molten salt system.The optimum process parameters are determined:electrolysis temperature is 1050℃,electrolysis time is 90 min,tank voltage is 3.5 V,La2O3 concentration is 1%.This process greatly reduces the time of electrode oxidation,and the current efficiency is achievable to 66.83%,and the high purity metal V substance without carbon and other metal impurities can be prepared.In the electrolysis process,the electrolysis current increases with the increase of La2O3 addition,and the background current also increases accordingly.The addition of La2O3 will accelerate the electrolysis process,and after the concentration of La2O3 increases to 1%,the rate of electrolysis tends to stabilize.The electrolysis product is loose and porous metal V,without the formation of Al or AlV alloy.Since La and V are not alloyed,the electrolysis process is accelerated by replacing Al heat with La heat.The electrolysis process follows a three-boundary(3PIs)simulation process.