Sulphide Capacity of CaO–SiO₂–Al₂O₃–MgO System Relevant to Low MgO Blast Furnace Slags

Abstract

Desulphurization has been of more importance to control the quality of hot metal in blast furnace (BF) with increasing utilization of low-grade iron ores and poor-quality fuels as well as reducing the slag volume by decreasing MgO concentration. To improve performance with better understanding the desulphurization in BFs, sulphide capacities of CaO–SiO₂–Al₂O₃–MgO system relevant to BF slags were experimentally determined using gas-slag equilibration technique. The results show that sulphide capacity increases with the increase in temperature, CaO/SiO₂ weight ratio and MgO at fixed Al₂O₃ concentration. The experimental results were further compared with sulphide capacity obtained from available models in open literature. In addition, the equilibrium sulphur partition ratio between slag and hot metal was calculated from sulphide capacity with oxygen activity in the melt, which is also compared with industrial data and the laboratory experiments of kinetic desulphurization of hot metal.