| 초록 |
A mathematical model has been developed to elucidate the degradation phenomenon of iron ore particles and its effect on reduction degree in a two-stage fluidized bed system. This model includes the reduction kinetics of iron oxides and predicts particles size distribution in the bed. Although the particle degradation is dependent on kind of iron ores, it was found that eighty to ninety percent of overall degradation is occured in a prereduction stage mainly due to thermal stress and volume expansion. The degradation of particles in the final stage is not significant, but is mainly due to interparticle collicion and abrasion. it was also found that to obtain a target reduction degree, it is of great importance to control the bed temperature and the residence time of particles in R1 rather than in R2. Optimum range of residence time was 15-20 minutes in the prereduction stage; 30-35 minutes in the final reduction stage.
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