1, heating cover agent in addition to low thermal conductivity material, add a certain proportion of heating material, in the metal liquid under the action of heat, oxidant to provide oxygen, reducing agent oxidation heat, and extend the riser metal liquid solidification time。
2, prolong the time the riser top crust, riser steel water for a long time in atmospheric pressure, greatly improve the feeding effect, which is favorable for gas in casting and inclusion, reached the purpose of purifying molten steel, and steel sound, low scrap rate。 Three
In the case of different heat preservation covering, the mouth shrinks into a dish flat bottom or a hemispherical bottom, and the mouth shape of the riser is approximately U shape.
4. Thermal insulation covering material is composed of low thermal conductivity material, such as expanded perlite, expanded graphite and so on.