To stably achieve the preliminary treatment of the hot metal at a low cost by sucking and removing foaming slag from the opening part of a reaction vessel by a suction device outside the vessel to rapidly remove the slag foaming in a short time in the preliminary treatment in the reaction vessel.
The hot metal stored in a torpedo 1 is preliminarily treated by blowing a desiliconizing agent, the desulfurizing agent, etc., from an immersion lance 8. The slag foaming is detected by a foaming sensor 7 arranged on an opening part 1a of the torpedo. In response to the detection, a suction nozzle waiting immediately below a dust collection duct 2 arranged above the torpedo 1 is lowered onto the foaming slag, and a vacuum pump 6 is operated. The foaming slag is sucked by the suction nozzle, and separated and removed by a slag separator 5 through the piping 4. The suction nozzle is supported so as to be freely elevated and lowered, and preferably evaded from hot opening part 1a in a normal practice. The foaming slag can surely be prevented from flowing out thereby.
TAKADA SHIGENOBU
TAKAHASHI KIYOSHI
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