Liquid structure evolution of molten iron in blast furnace hearth

Abstract

The iron-carbon interfacial reaction between molten iron and carbon brick was carried out to simulate the working condition of blast furnace (BF) hearth. The carbon content in molten iron after the reaction was detected to be 5.0% which was almost saturated. XRD and SEM-EDS were conducted on the surface of polished rectangle iron before and after iron-carbon interfacial reaction. Fine striped graphite was observed in iron before iron-carbon interfacial reaction, a large amount of flake-like graphite was observed in iron after iron-carbon interfacial reaction. As a structure-sensitive physical property, the viscosity of molten iron was the macroscopic expression of its liquid structure. The liquid structure of molten iron (Fe-4.5%C, Fe-5.0%C) was measured through a high temperature X-ray diffractometer. The X-ray original diffraction intensity, the structure factor, the pair distribution function, the radial distribution function, and the main parameters of molten iron were obtained through the calculation. The presence of pre-peak in the structure factor indicated that there was a medium-range order in molten iron, some compounds or cluster of atoms might exist in molten iron, the structure model of atoms in liquid Fe-4.5%C was predicted through the structure parameters. The increase of carbon content after iron-carbon interfacial reaction was the essential reason for liquid structure evolution of molten iron in hearth.