Dissolution behaviour of limestone in converter slag: evolution of microstructure and reaction interface

Abstract

The dissolution behaviour of limestone in converter slag at 1300–1400°C was studied, and the effects of the slag temperature and basicity were examined. The results showed that the increment of slag temperature was favourable to the formation of cracks and macropores in the generated lime, and the dissolution of the lime into liquid slag was promoted by the slag penetrating through these cracks and macropores. While the slag basicity increased from 0.5 to 1.0, the 2CaO·SiO₂ phase gradually formed around the lime and became discontinuous due to the effusion of CO₂ formed by limestone decomposition. Moreover, the thickness of the CaO–FeO layer sharply increased during the coexisting period of the limestone decomposition and the lime dissolution. After the complete decomposition of the limestone, a continuous 2CaO·SiO₂ layer formed at the lime/slag interface and the growth rate of the CaO–FeO layer obviously decreased, which hindered the lime dissolution.