Sulphide Capacities of CaO‐SiO2‐Al2O3‐MgO Slags

In Japanese steelworks, hot metal is now being produced by a scrap melting process. With this process, removals of sulphur is very much handicapped because of very high sulphur levels (0.04‐ to 0.09‐ pct by weight) and relatively low tapping temperatures (1623 to 1723 K). In order to overcome such handicaps, the authors explored on the respective phase diagrams. These explorations revealed that {CaO‐SiO₂‐Al₂O₃‐MgO} slags with Al₂O₃ contents of 30‐ to 35‐pct by weight would be good candidates as reagents for sulphur removal from high sulphur hot metal at relatively low temperatures. For better understanding of the thermodynamic properties of the candidate slags, in this study, sulphide capacities were determined through gas/slag equilibrium technique. The experimental results suggest that there would be, at least, a “window” to remove sulphur from high sulphur hot metal as relatively low temperatures.