| In order to estimate the contribution of smelting reduction rate by carbon in slag, the reduction rate of FeO was measured by using a mass spectrometer technique. Series of experiments were carried out with wide ranges of FeO content to illuminate the dependence of rate limiting step on FeO content in slag. Reacting procedure can be divided into three regions; incubation, steady state reaction, and transition period. Since rates at incubation and transition periods are changed by reacting condition, rate at steady state period is generally used to represent the overall reduction rate. The reduction rate of FeO was increased with increasing FeO content in slag. The dependence of reduction rate on FeO content can be expressed as follow : r=4.4 × 10^(-5) a^(1.34)_(FeO) or r=1.67×10^(-7)(wt%FeO)^(1.34) The activation energy was measured to be 60.6kcal/mol for l0wt%FeO experiment. From the results of present study, chemical reaction at the interface between gas and carbon would be a rate limiting step for high FeO content. However role of FeO mass transfer in slag became important with decreasing FeO content. Consequently, the reaction mechanism was changed from chemical reaction at carbon surface to mixed controlling step of chemical reaction and mass transfer of FeO in slag by decreasing FeO content. Appling present results for FeO reduction rate by solid carbon to the pilot operation of smelting reduction process, the contribution of reduction rate by solid carbon was estimated to be about 20-30%. |
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