Investigation of Blowing High Silicon Hot Metal by Double Slag Process

Abstract

For integrated steel plants, hot metal with silicon content larger than 1.0% cannot be used in BOF (Basic Oxygen Furnace) process unless mixed with low silicon-content hot metal. Slopping is the major disadvantage of BOF operation with high silicon-content hot metal during blowing. But for steel plants with newborn single blast furnace, such as Dragon Steel Corporation, the way of mixing hot metal cannot be delivered in exception of dumping. In order to decrease the amount of hot metal dumping, China Steel Corporation successfully developed a new BOF process for blowing hot metal with silicon content higher than 1%, with a maximum value reaching 2%. Through persistent tests in 250-ton BOF by studying slag properties and blowing models, a double-slag method was developed to blow high silicon content hot metal. During blowing test of high silicon hot metal for three heats, desiliconization slag was sampled during deslagging. The slag composition and mineral phase were examined by the usual XRF chemical analysis, as well as SEM and XRD studies to provide an important reference in the slagging practice for double slag operation.