The influence of magnesium and aluminum salts as impurities on the hydrolysis of titanyl sulfate was *** degree of TiOSO4 conversion to hydrated titanium dioxide(HTD) and the particle size of HTD were measured as fu...
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The influence of magnesium and aluminum salts as impurities on the hydrolysis of titanyl sulfate was *** degree of TiOSO4 conversion to hydrated titanium dioxide(HTD) and the particle size of HTD were measured as functions of the concentrations of MgSO4 and Al2(SO4)3 in the TiOSO4 *** Boltzmann growth model,which focuses on two main parameters,namely the concentrations of Mg2+ and Al3+(ρ(Mg2+) and ρ(Al3+),respectively),fits the data from the hydrolysis process well with *** samples were characterized by ICP,SEM,XRD,and laser particle size *** is found that the addition of Mg SO4 simultaneously improves the hydrolysis ratio and the hydrolysis rate,especially when F(the mass ratio of H2SO4 to TiO2) is high,hydrolysis ratio increases from 42.8% to 83.0%,whereas the addition of Al2(SO4)3 has negligible effect on the chemical kinetics of HTD precipitation during the hydrolysis process,hydrolysis ratio increases from 42.8% to 51.9%.An investigation on the particle size of HTD reveals that the addition of Mg SO4 and Al2(SO4)3 clearly increases the size of the crystallites and decreases the size of the aggregates.
The reduction behaviors of FeO·V2O3 and FeO·Cr2O3 during coal-based direct reduction have a decisive impact on the efficient utilization of high-chromium vanadium-bearing titanomagnetite concentrates. The ef...
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The reduction behaviors of FeO·V2O3 and FeO·Cr2O3 during coal-based direct reduction have a decisive impact on the efficient utilization of high-chromium vanadium-bearing titanomagnetite concentrates. The effects of molar ratio of C to Fe n(C)/n(Fe) and temperature on the behaviors of vanadium and chromium during direct reduction and magnetic separation were investigated. The reduced samples were characterized by X-ray diffraction(XRD), scanning election microscopy(SEM) and energy dispersive spectrometry(EDS) techniques. Experimental results indicate that the recoveries of vanadium and chromium rapidly increase from 10.0% and 9.6% to 45.3% and 74.3%, respectively, as the n(C)/n(Fe) increases from 0.8 to 1.4. At n(C)/n(Fe) of 0.8, the recoveries of vanadium and chromium are always lower than 10.0% in the whole temperature range of 1100-1250 °C. However, at n(C)/n(Fe) of 1.2, the recoveries of vanadium and chromium considerably increase from 17.8% and 33.8% to 42.4% and 76.0%, respectively, as the temperature increases from 1100 °C to 1250 °C. At n(C)/n(Fe) lower than 0.8, most of the FeO·V2O3 and FeO·Cr2O3 are not reduced to carbides because of the lack of carbonaceous reductants, and the temperature has little effect on the reduction behaviors of FeO·V2O3 and FeO·Cr2O3, resulting in very low recoveries of vanadium and chromium during magnetic separation. However, at higher n(C)/n(Fe), the reduction rates of FeO·V2O3 and FeO·Cr2O3 increase significatly because of the excess amount of carbonaceous reductants. Moreover, higher temperatures largely induce the reduction of FeO·V2O3 and FeO·Cr2O3 to carbides. The newly formed carbides are then dissolved in the γ(FCC) phase, and recovered accompanied with the metallic iron during magnetic separation.
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