The Influence of Operating Condition on Dephosphorization and Desulphurization Reactions of Hot Metal with Lime-based Flux

Abstract

In order to estimate the improvement of dephosphorization and desulphurization of hot metal by adding lime-based flux, 100 t scale tests are conducted. Two kinds of stirring methods, mechanical stirring by impeller and that by injection, are adopted. Injection method is more practical than mechanical stirring method because of higher reaction efficiency. Dephosphorization ratio of about 85% and desulphurization ratio of about 60% can be achieved on a commercial scale by adding 15 kg/t of CaO, 34 kg/t of CaCl₂+CaF₂ and a certain amount of oxygen source, oxygen gas and/or iron oxide. One of the most important techniques is fluid slag formation of high basicity and low FeO content. Dephosphorization reaction is strongly affected by several kinetic factors, for example, dissipation energy of bath ε. The relationship between ε and apparent rate constant of dephosphorization k'_P can be expressed as k'_P=0.14ε^0.58.