A Kinetic Model for Limestone Decomposition under BOF Steelmaking Condition

Abstract

In BOF steelmaking process, high-activity lime has been widely used to form an appropriate slag as a medium for the removal of non-volatile impurities from the hot metal treated. In recent years, however, great attention has been paid to the possibility of directly using limestone instead of lime in the furnace. Despite laboratory experiments and industrial trials have proven the feasibility of the technique, a list of underlying issues still require more considerations, e.g., thermodynamics and kinetics of steelmaking reactions and limestone evolution during blowing under the new condition. The main motivation behind this paper is to establish a kinetic model for limestone decomposition under BOF steelmaking condition on the basis of shrinking core hypothesis. The Kozeny-Carman equation that correlates pressure gradient with the corresponding velocity is integrated into the model in order to account for the CO 2 flow through the lime layer packed with small grains. The model is demonstrated using a set of experimental data and is finally verified by comparing the obtained thermal conductivity and grain size with available values in the literature.

Role of self-disintegrating effect produced by decomposition of limestone core on accelerating dissolution of lime in CaO–SiO 2 –FeO x slag

“…In recent years, the application of limestone instead of lime for slagging has attracted a lot of attentions [16][17][18]. The formed CO 2 gas by limestone decomposition can destroy the dicalcium silicate reaction layer at the slag/lime interface, thus, which can speed up the mass transfer of lime dissolution during limestone slagging mode [18].…”

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

“…Compared with the conventional lime steelmaking process, the dissolution of limestone is accompanied by the decomposition reaction of limestone in the limestone steelmaking process. The decomposition of limestone in converter slag is a strong endothermic reaction which has been studied by many researchers [13][14][15]. Deng et al [16] studied the dissolution of limestone in slag at 1600°C and concluded that the structure of the decomposed limestone became very dense at the boundary, resulting in a dense CaO layer at the surface of the generated lime.…”

“…Compared with the conventional lime steelmaking process, the dissolution of limestone is accompanied by the decomposition reaction of limestone in the limestone steelmaking process. The decomposition of limestone in converter slag is a strong endothermic reaction which has been studied by many researchers [13–15]. Deng et al.…”