高炉出銑樋材のスラグ-溶銑界面における局部溶損機構と防止策

抄録

Slag film formed between trough material and metal is always in liquid state in the local corrosion zone, while percentage of solid phase of the film in the metal zone increases with increasing dipping time. Changes in the composition of the slag film are detected along the surface of the trough material in directions vertical to and also perpendiculer to the surface in the corrosion zone. By combining the above results with those obtained in the previous studies¹⁾²⁾ on the local corrosion of this system, the following mechanism of the local corrosion is proposed: The local corrosion is caused by the active motion of the slag film induced by the Marangoni effect and also by CO bubbles evolved along slag film-metal interface.
Local corrosion zone in the blast-furnace trough is extended in vertical direction mainly due to the formation and removal of the film caused by the up and down motion of the slag-metal interface level caused by the variation of the flow rate of pig iron in the trough.
Some countermeasures against the local corrosion are proposed from the standpoint of suppressing the film motion.