Limestone Dissolution in Converter Slag: Kinetics and Influence of Decomposition Reaction

Abstract

Dissolution rate of limestone in converter slag is a key to evaluate the feasibility of limestone slagging mode during steelmaking process. In this work, kinetics of limestone dissolution in converter slag at 1300–1400°C were studied and the influence of decomposition reaction were investigated. The results showed that the dissolution process of limestone in converter slag can be divided into three stages: stagnation stage, coupling stage and sole dissolution stage. Higher slag temperature and lower slag basicity were conducive to reduce the duration time of stagnation stage and obtain higher dissolution degree. The coupling stage of limestone dissolution was confirmed to be controlled by the chemical reaction, whereas diffusion through the boundary layer as well as combination of controlling steps was the rate limitation at the sole dissolution stage under different slag basicities. The kinetics parameters were determined. In addition, CO₂ bubbles generated from decomposition reaction could provide a certain enhancement of limestone dissolution and inhabit the formation of 2CaO·SiO₂ phase at the coupling stage of limestone dissolution in converter slag.