Improvement of Sinter Productivity by Adding Return Fine on Raw Materials after Granulation Stage

摘要

In order to increase the permeability of the sintering bed for sinter ore productivity, RF-MEBIOS (R eturn F ine - M osaic E mb edding I ron O re S intering) process, in which return fine as dry particle is added on granulated raw materials and then they are charged into sintering machine, is proposed. In RF-MEBIOS, it is demonstrated by pot tests that productivity increases at the same moisture content in sinter mixture at charging. This productivity increase is caused by higher permeability in sinter packed bed due to two major phenomena. One is increasing the pseudo-particle size at granulation and the other is decreasing the bulk density of sinter packed bed after charging. The former is achieved by a higher moisture content in the raw materials at granulation, which has the role of decreasing small size of pseudo-particle (–0.25 mm). The latter is achieved by higher friction in the packed bed composed of dry and wet particles compound, which has a role of decreasing bulk density. In the development of RF-MEBIOS, return fine was chosen as the dry particle because it is dry when produced by the sintering machine. The sinter productivity increases with the increase of the quantity of the return fine added after granulation stage. The effect of pseudo-particle (–0.25 mm) ratio and ε on flame front speed were evaluated as 55% and 41% to increase of frame front speed, respectively.Effect of RF-MEBIOS on sinter productivity is confirmed in No.3 sinter plant in Kashima Steel Works. Under the condition of constant moisture content in sinter mixture at charging, this improvement degree is proportioning to the ratio of bypass return fine which is added to granulated the other sinter materials without granulation. It means granulation at higher moisture has superiority compared to increase of fine material in bypass return fine.Finally, RF-MEBIOS method is installed on three commercial sintering machines (Kashima, Wakayama, and Kokura) belonging Sumitomo Metals. In all three sinter plants, productivity increase has been confirmed. Therefore, introducing RF-MEBIOS has been demonstrated to cause a universal improvement of sinter productivity.