Petroleum-based soft pitch mixture and closing material for molten metal tapping hole

Abstract

A petroleum-based soft pitch mixture which has a low polycyclic aromatic hydrocarbon concentration and can be easily adjusted in viscosity depending on an application, and a closing material for molten metal tapping hole which emits a small amount of a polycyclic aromatic hydrocarbon during use. A petroleum-based soft pitch mixture obtained by mixing: a petroleum-based soft pitch having a softening point of 40° C. or higher and lower than 150° C.; and a distilled oil having a boiling point range of 230° C. to 280° C., wherein a content of the distilled oil is 10% by mass to 45% by mass, the balance being the petroleum-based soft pitch and unavoidable impurities. The closing material for molten metal tapping hole is obtained by mixing the petroleum-based soft pitch mixture as a binder with a refractory raw material. As the polycyclic aromatic hydrocarbon, the content of benzo [a] pyrene and naphthalene is controlled.

Dependencies are inferred from the claim text.