Effects of ash amount and molten ash's behavior on initial Fe-C liquid formation temperature due to iron carburization reaction

In the current trend, a low carbon operation of blast furnace is going to make liquid permeability severe condition due to thinning of coke layer around cohesive zone. An iron carburization reaction is one of the most important reactions at the cohesive zone, because an enhancement of the reaction has a positive possibility to improve a metal dripping behavior from cohesive zone. Although it is thought ash of carbonaceous material has a negative effect on the reaction, there is not enough correctly focused knowledge on behavior of the ash in iron carburization reaction. In this study, several kinds of carbonaceous material samples with ash remove treatment by acid solution were prepared. The carbonaceous material samples were applied for "in-situ" observation of molten iron formation behavior due to iron carburization reaction under a constant heating rate condition with inert gas atmosphere. It was found that the acid treatment decreased not only amount of the ash in the carbon samples but also Na concentration of the ash. Decreasing of ash content in carbonaceous material decreased initial Fe-C liquid formation temperature because obstruction on reaction area of iron carburization reaction was decreased. Decreasing of Na content in ash caused changing of molten ash's properties, increasing of melting temperature and decreasing of wettability to iron and carbon. In case of without the acid treatment, it was thought molten ash could behave as a barrier at a reaction interface of iron carburization due to good wettability from lower temperature than initial Fe-C liquid formation temperature.