Thermodynamic Calculations of Desulfurization in Low Carbon Steel-Slag System

by Jhewn-Kuang Chen, Keng-Li Chu, Wei-Te Wu, Chi-Ming Lin

Publisher - National Taipei University of Technology, National Chung Hsing University

Category - General Novel

A series of CaO-Al2O3-SiO2-CaF2 synthesis slags were made to react with low carbon steel containing 0.05% C and 0.05% S by thermodynamic equilibrium calculations. The commercial thermodynamic software, Thermo-Calc, is employed to evaluate the capability of desulfurization with variations of slag percentage, CaO, Al2O3, SiO2, CaF2, and MnO concentrations. With 3 wt.% of slag addition in the molten steel, the reduction of sulfur in steel is especially prominent when CaO concentration is over 50 wt.% in the slag. The partition ratio of sulfur in slag and steel increases to over 60. It is also observed that the addition of CaF2 has very limited capability for desulfurization. However, CaF2, as a flux, reduces the melting point of slag which is beneficial to the increase of fluidity and reactivity of slag in molten steel. CaF2 aids to desulfurize kinetically rather than thermodynamically.

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