Phase and Reaction Behavior of the Iron-Coke Interface Along the Coke-Free Area in a Dissected Blast Furnace Hearth

摘要

Deadman samples in a dissected commercial blast furnace were systematically investigated through microstructure analysis. An obvious layered structure can be observed in deadman samples, which can be described as a mineral layer sandwiched between coke and iron. The existence of the mineral layer hinders the dissolution of coke into molten iron. Solid particles of CaS were found at the slag-iron interface and inside the deadman coke. The decrease of the slag basicity and the precipitation of solid particles of CaS caused by the desulfurization reaction between slag and iron are important reasons for the deterioration of the fluidity of the slag phase in the mineral layer. Alkalis were also found in the minerals of the deadman coke, which may be an important source of alkali metal erosion of the furnace sidewall /bottom refractory. In addition, titanium nitride (Ti4.3N) clusters were found on the interface between the mineral layer and the iron, which can promote the formation of the titanium-rich layer in hearth. At the same time, the precipitation of titanium nitride in the molten iron may also be an important reason for hearth stacking/inactivity, which hindering the utilization efficiency of deadman coke. GRAPHICS .