All Pellets Operation in Kobe No. 3 Blast Furnace under Intensive Coal Injection.

In Kobe No. 3 blast furnace (third campaign) (inner volume: 1845 m3; blown in on April 5, 1983), the use of pellets was begun as a result of suspended operation of the sintering plant in the end of May 1999 and Kobe 3BF began all pellets operation (pellet: 73%; lumpy ore: 27%) in the end of September 2001. This is dedicated to the advancement of all pellets operation under intensive coal injection with the bell-less blast furnace. A study has been made of the deepening of understanding on the phenomena of softening and melting properties by using the mixture of dolomite-fluxed pellets and low basicity pellets. In order to prevent the growth of cohesive zone root by using of low basicity pellets, the charging technique of time-series discharging based on model experiments was developed and applied to an actual furnace. To achieve the high accurate burden distribution control, the change of ore falling trajectory by fling-up of pellets inside the rotation chute was monitored and corrected. With respect to slag and metal chemistry under the low slag ratio operation with use of low basicity pellets, securing the slag fluidity and desulfurizing efficiency was designated as control points.