Study On The Rust Reaction Process Based On A Novel Gas-liquid-solid Three-phase Reactor

In this paper,reduced ilmenite is used as raw material,based on a new gas-liquid-solid three-phase tubular reactor,combined with potential-pH diagrams for thermodynamic analysis,and the effects of different corrosion systems on the corrosion behavior of reduced ilmenite are discussed.And the product has been pickled and analyzed,and the main research results are as follows:(1)The E-pH diagram shows that from 25-90℃,with the increase of temperature,the passivation area of iron continues to increase,and the pH required to avoid passivation of rust reaction at high temperature is lower.The equilibrium potential of Fe2+oxidized to Fe3+increases,and oxidation becomes more difficult,which is conducive to the outward diffusion of Fe2+.With the increase of Fe2+concentration at 90℃,a lower pH is required to inhibit passivation during the reaction;the corrosion potential of metal iron increases to inhibit the occurrence of rust reaction.At this time,the potential at which Fe2+ is oxidized to Fe3+ does not change,and the Fe2+ accumulated inside the particles during the reaction will not promote the oxidation to Fe3+.(2)In the hydrochloric acid corrosion system,the grade of TiO2 reaches 87%in the tubular reactor for 3.5 h.With the increase of the gas flow rate and the acceleration of the stirring rate,the removal rate of the TFe content in the reduced ilmenite increases.(3)In the ammonium chloride system,the reaction time is 3h,and the grade of TiO2 reaches 87%.And there is no passivation phenomenon.In the ammonium chloride corrosion system,the decrease rate of TFe content after adding sucrose slows down,which is not conducive to corrosion.(4)Sulfuic acid washing can remove some impurities,and the effect will increase as the temperature rises.The content of SiO2,Al2O3,and CaO is reduced after pickling.The two impurities of MnO and MgO are not affected by washing,the grade of TiO2 reaches 88.8%,and the recovery rate of TiO2 is 96.67%.(5)The morphology of the product after rust is honeycomb,the particle size is reduced,and the particle size distribution is more concentrated,which meets the requirements of the industry.The main phase is rutile TiO2.The main iron by-product produced by the hydrochloric acid system is γ-FeOOH,followed by α-Fe2O3.In the particle size distribution,the finer should be α-Fe2O3,and the coarser should be γ-FeOOH.In the ammonium chloride system,the phase is mainly α-Fe2O3,followed by γ-FeOOH,and its particle size distribution is concentrated.