Sulfur distribution in preparation of high titanium ferroalloy by thermite method with different CaO additions.

Ferrotitanium is used as a deoxidizer and alloying agent during steelmaking process, which has a high demand for sulfur control. Sulfur was introduced from raw materials in the process of producing ferrotitanium by thermite method, where CaO was used as fluxing agent. At the same time, CaO has a great desulfurization capability. Effects of CaO addition on the distribution of sulfur in high titanium ferroalloy prepared by thermite method were studied in this work. The equilibrium diagram of Ti–Al–Fe–S system was calculated by FactSage 6.4 software package with FactPS and FTmisc database. The alloy and slag samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), inductively coupled plasma atomic emission spectrometer (ICP-AES), X-ray fluorescence (XRF) and high-frequency infrared ray carbon sulfur analyzer. The result indicates that the sulfur in the alloy firstly exists in the form of liquid FeS, thereafter TiS (s) and eventually Ti₂S (s) during cooling. The sulfur is mainly distributed in the alloy, and only a small amount of sulfur remains in the slag. Moreover, it is noted that the sulfur in the alloy does not distribute homogeneously, and it exists in the form of solid solution phase, (Ti, Al, Fe)S. S content in the slag, the sulfur capacity of the slag and the sulfur distribution ratio (L_S) all increase with the increment of CaO addition, while S content in alloys decreases. [ABSTRACT FROM AUTHOR]