| 摘要 |
PURPOSE:To prevent the sintering of packing materials in a lower layer and to smooth and stabilize the operation for treating molten metal by packing the granular packing material of a high m.p. in the lower layer of the closed nozzle in a charging nozzle part in the bottom of a vessel for molten metal and the granular packing material of a low m.p. in the upper part thereby forming a foamed and expanded heat insulation layer in the upper layer when the molten metal is contained in the vessel. CONSTITUTION:A granular packing material 5 of a high m.p. having m.p. exceeding the temp. of molten metal as a preventing material for clogging is packed in a sliding nozzle SN in a closed state up to the top end of the nozzle hole of the upper nozzle 3 theeof. A granular packing material 6 of a low m.p. which foams and melts at the temp. lower than the temp. of the molten metal is packed into the expansion nozzle hole of a nozzle rest brick 4 supporting the upper nozzle 3 up to the inlet thereof in succession to the above. The material 6 for which feldspar or the like is used is granulated to <=2.0mm. grain size and is put in a PE bag which is charged in the nozzle hole. Then a semi-molten film 7 and a foamed and expanded heat insulation layer 8 are formed on the surface of the packing material 6 by preheating or the heat of the molten metal, by which the sintering of the material 5 is prevented. When the upper nozzle 3 is opened, the unfoamed part 6 of the material 6 flows down then the layer 8 collapses and flows down, thus flowing from the nozzle hole together with the molten metal. |
