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Kinetics of thermal decomposition of hydrated minerals associated with hematite ore in a fluidized bed reactor
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作者 P.C. Beuria S.K. Biswal +1 位作者 B.K. Mishra g.g. roy 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2017年第3期229-239,共11页
The kinetics of removal of loss on ignition(LOI) by thermal decomposition of hydrated minerals present in natural iron ores(i.e.,kaolinite,gibbsite,and goethite) was investigated in a laboratory-scale vertical fluidiz... The kinetics of removal of loss on ignition(LOI) by thermal decomposition of hydrated minerals present in natural iron ores(i.e.,kaolinite,gibbsite,and goethite) was investigated in a laboratory-scale vertical fluidized bed reactor(FBR) using isothermal methods of kinetic analysis.Experiments in the FBR in batch processes were carried out at different temperatures(300 to 1200°C) and residence time(1 to 30 min) for four different iron ore samples with various LOIs(2.34wt% to 9.83wt%).The operating velocity was maintained in the range from 1.2 to 1.4 times the minimum fluidization velocity(Umf).We observed that,below a certain critical temperature,the FBR did not effectively reduce the LOI to a desired level even with increased residence time.The results of this study indicate that the LOI level could be reduced by 90% within 1 min of residence time at 1100°C.The kinetics for low-LOI samples(<6wt%) indicates two different reaction mechanisms in two temperature regimes.At lower temperatures(300 to 700°C),the kinetics is characterized by a lower activation energy(diffusion-controlled physical moisture removal),followed by a higher activation energy(chemically controlled removal of LOI).In the case of high-LOI samples,three different kinetics mechanisms prevail at different temperature regimes.At temperature up to 450°C,diffusion kinetics prevails(removal of physical moisture);at temperature from 450 to 650°C,chemical kinetics dominates during removal of matrix moisture.At temperatures greater than 650°C,nucleation and growth begins to influence the rate of removal of LOI. 展开更多
关键词 thermal DECOMPOSITION fluidized BEDS KINETIC analysis hydrated iron ORE ACTIVATION energy
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