Dissolution Behavior of Aluminum Titanate Inclusions in Steelmaking Slags

Abstract

The current work investigates the dissolution path and mechanism of aluminum titanate inclusions in steelmaking slags using a high-temperature confocal scanning laser microscope (CSLM). To study this phenomenon, a single particle of aluminum titanate is dissolved in slag at 1773 K. During the dissolution process, gas bubble evolution is observed. Further, the particle–slag system is rapidly quenched using helium at different stages of dissolution. The quenched samples are examined for distribution of the constituent elements: Al, Ti, Ca, and Si using the scanning electron microscope (SEM). Phases such as alumina, titanium-rich slag, and calcium titanate are detected at the particle–slag interface. The dissolution path of aluminum titanate is proposed in the following steps. First, aluminum titanate dissociates into alumina, titanium oxide, and oxygen while slag penetrates through the particle. In the next step, the alumina and titanium oxide dissolve in slag, and the oxygen leaves the system. The existence of gas bubbles enhances the overall rate of Al2TiO5 dissolution. The dissolution of Al2TiO5 appears to be controlled by mass transfer in the slag. Evidence in support of this finding is the particle–slag interface characterization by line scan analysis and calculated diffusivity values being inversely proportional to the viscosity of slag.