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In the recent operation of blast furnace, it is supposed that high gas permeability of burden is important for low RAR and high PCR operation. In this work, sinter quality for improvement in gas permeability of blast furnace was investigated with reduction degradation and under-load-reduction tests. As the results, the reduction degradation of sinter is deteriorated by increasing H2 concentration in the reduction gas under the condition of below 3.8 vol% H2. However, over 3.8 vol% H2, increase of H2 has no effect on the reduction degradation because the diffusion of reduction gas in the sinter is limited. On the other hand, from the under-load-reduction test, there is possibility that increase in H2 concentration of reduction gas and decrease in slag ratio in sinter are effective to improve gas permeability of lower part of blast furnace rather than reducibility of sinter. Due to adoption of these experimental results to a 2-dimentional mathematical simulation model, the precision of pressure drop calculation of blast furnace was improved. It is considered from the evaluation by this model calculation that the RDI, a slag ratio and the slag viscosity as the sinter properties are greatly influence on the permeability of blast furnace.

Synopsis : Rapid in-flight reduction of fine iron ore transported with CO, H 2 and/or CH 4 gas has been studied for direct use of fine iron ore in iron-making process. In this work, the mechanism and the kinetic of the reduction by CH 4 gas were accurately investigated with spherical wustite fine particles. The spherical wüstite fine particle as fine iron ore was prepared to simplify the reduction rate analysis. Reduction temperature was varied from 1373 to 1573K. As the result, fractional reduction of spherical wüstite by CH 4 gas reached over 80% at 1573K within 1 sec. From the cross section observation of the particle after reduction, it was found that the periphery of the wustite particle was metallized by reducing reaction and un-reacted wüstite core remained inside. Therefore, it was indicated that the reduction progressed topochemically in this experimental condition. In the reduction rate analysis, it was found out that the reduction rate by CH 4 was higher than that by H 2 or CO. From the carbon concentration analysis, it was found that the phase of the metallic shell during reduction was not only solid state but also liquid state. From the above-mentioned kinetic analysis, it was concluded that the reduction rate determining-step by CH 4 was chemical reaction on Fe-FeO interface and the reduction of wüstite was preceded by the carbon dissolved into metallic shell from CH 4 gas.

緒言 ・佐藤 道貴 2）Evaluation of Sinter Quality for Improvement in Gas Permeability of Blast Furnace Naoyuki Takeuchi, Yuji iwami, Takahide higuchi, Koichi Nushiro, Nobuyuki oyama and Michitaka saTo Synopsis : In the recent operation of blast furnace, it is supposed that high gas permeability of burden is important for low RAR and high PCR operation.In this work, sinter quality for improvement in gas permeability of blast furnace was investigated with reduction degradation and under-loadreduction tests. As the results, the reduction degradation of sinter is deteriorated by increasing H 2 concentration in the reduction gas under the condition of below 3.8vol% H 2 . However, over 3.8vol% H 2 , increase of H 2 has no effect on the reduction degradation because the diffusion of reduction gas in the sinter is limited. On the other hand, from the under-load-reduction test, there is possibility that increase in H 2 concentration of reduction gas and decrease in slag ratio in sinter are effective to improve gas permeability of lower part of blast furnace rather than reducibility of sinter. Due to adoption of these experimental results to a 2-dimentional mathematical simulation model, the precision of pressure drop calculation of blast furnace was improved. It is considered from the evaluation by this model calculation that the RDI, a slag ratio and the slag viscosity as the sinter properties are greatly influence on the permeability of blast furnace.

No abstract