Study On Carbonization Reduction Process And Mechanism Of Rare Polymetallic Mixed Concentrates

Rare earth,niobium,zirconium and other rare metals not only play an important role in various sectors of the national economy?such as aerospace,energy,electronics,chemical industry,etc.?,but also play an increasingly important role in science and technology and other fields.And with the continuous progress of science and technology and the gradual improvement of people's quality of life,the consumption demand for rare metals increases year by year.Ask for niobium,zirconium,rare earth and other applications and resource reserves to elaborate.In order to provide the necessary basic physical and chemical theoretical basis and necessary experimental parameters for chlorination metallurgy through the carbonization experiment,a new and efficient metallurgical extraction method is finally established.In this paper,the correlation thermodynamic analysis of the main element minerals in the mixed rare metal concentrate was carried out and the relationship between gibbs free energy and temperature was fitted.The results showed that the initial temperature of iron oxide being reduced to metal was 720?.For minerals such as gangue in ore,the gibbs free energy of FeO reaction is negative below 857?.Niobium oxide is reduced at 2567?or above.Cerium oxide needs to be reduced to a metal at temperatures above 2500?While the decomposition temperature of zircon is 1676?,the reaction temperatures required to produce ZrC and SiC phases are 1653?and 1543?,respectively.The reduction roasting of mixed rare earth concentrate at a temperature below1225?was studied,and the effects of different reduction roasting systems on the metallization rate of iron ore were studied.The study showed that the optimal reduction temperature was 1175?,the time was 50min,and the metallization rate was 92.52%when the carbon content increased to 1.5.The phase changes of the reaction products under different reduction calcination time were studied:with the prolongation of reduction time,the diffraction peak of rare earth increased gradually in the energy spectrum,and the rare earth elements were enriched.After deep reduction of the mixed concentrate at high temperature,the results showed that the carbonization rate of zirconium reached 75%when the calcination temperature was 2000?with the carbon content of C/O=3.5 and the heat preservation time was120min.Chemical analysis,XRD,SEM,EDS and other analytical methods were used to systematically study the phase changes and element migration at different reduction temperatures.The results show:Zirconium 1600?basic decomposition,at 2000?,zirconium carbonization is basically completed.At 2200?,the SiO₂ diffraction peak basically disappeared,and the Zr,Si and Fe phases reacted to form a new Zr₄Fe₄Si₇ phase.With the increase of temperature,rare earth aluminate,rare earth silicate phase and rare earth ferrosilicon alloy phase gradually appeared in the reduced materials.When the temperature rose to 2200?,carbon and phosphorus rare earth phase appeared.Comprehensive analysis shows that 2000?is the best temperature for high temperature carbonization reduction.