SLAG DETECTING METHOD IN MOLTEN METAL VESSEL

PURPOSE:To effectively prevent a slag from being mixed into an outflow molten metal flow, by detecting the slag by a variation of electromotive force due to molten metal displacement and a slag displacement of a molten metal vessel. CONSTITUTION:When depth of molten steel in a converter A has reached a prescribed value, a conductive slag stopper 5 is inserted into the converter A, and a steel outflow port 15 is stopped by the lower end of the stopper. After a prescribed interval of time has passed, the steel outflow is restarted by raising the stopper 5 by a set extent. At the initial period of steel outflow, the stopper 5 and a shell 4 become in conduction by molten steel 2, but a voltmeter 8 provided on a conduction line 7 is not varied yet since electromotive force is not generated. When the tip of the stopper contacts with a slag 1, however, the voltmeter 8 detects electromotive force generated between the slag 1 and the molten steel 2. This current sends a signal to a hydraulic pressure unit 10 through an amplifier 9, and operates a driving mechanism 11 of the stopper 5. Subsequently, the stopper is lowered again, and reduces an outflow gap of outflow steel or stops the steel outflow port 15.