Conical gas hood for casting ladles - where clay seal is formed between bottom of the hood and the top of the ladle

摘要

Sealed hood is described for a casting ladle or similar vessels used for the treatment and transport of molten metals. The hood is a cone tapering upwards to a hole for the escape of reaction gas, whereas the bottom rim of the cone is connected by a circular row of feet to a concentric, conical skirt which tapers downwards, leaving an annular gap (a) between the skirt and the bottom rim of the hood, which is inside the skirt. Gap (a) contains a plastic sealing mass located below a compression ring pushed downwards so the mass forms a seal between the hood and the top rim of a ladle. The conical hood pref. has a height:dia. ratio H:D between 1:1-1:2; and the bottom edge of the skirt is pref. 3-5 cm lower than the bottom rim of the hood. The plastic mass is pref. a mineral clay not susceptible to expansion by foaming. Used e.g. for the desulhurisation of crude iron, using Na2CO3 fed by CH4 through a lance, so CO and H2 are evolved by the molten bath.