Sulphide Capacity and Mineralogy of BaO and B2O3 Modified CaO–Al2O3 Top Slag

BaO and B2O3 were used to improve the metallurgical properties and valorisation potential of CaO–Al2O3 based top slag. The sulphide capacity of BaO–B2O3 modified CaO–Al2O3 based top slag was measured and compared with calculated values using the FactSage software. The effect of slag basicity (CaO + MgO)/(Al2O3 + B2O3) = 0.6–1.4 and BaO content on sulphide capacity was discussed. The mineralogy of the slag after experiments was observed. The crystallisation path of the slag during cooling was predicted based on a Scheil-Gulliver model. Consequently, the effect of the slag basicity and B2O3 on slag mineralogy and glass formation ability was discussed. It is found that the sulphide capacity is mainly influenced by slag basicity. BaO addition improves the slag sulphide capacity only for slag with low basicity (< 1.2). B2O3 addition enlarges the liquid region at 1600°C but decreases the slag sulphide capacity. High basicity and B2O3 addition benefit the glass formation and would improve the slag valorisation potential in applications where the glass content is important.