Research on slagging by limestone during BOF steelmaking process

On the basis of analysis of limestone decomposing and slagging mechanism, the changing of surplus heat was studied using limestone instead of lime as the slagging agent during steelmaking process, which indicates that hot metal added ratio can reach approximate 86.1% if using lime entirely. If limestone is applied in the steelmaking process to replace all limes for slagging, the hot metal ratio can reach up to 97.0%. On this basis, the metallurgical results of using limestone instead of lime for slagging in 60 t con-verter were studied. The results show that the content of TFe in slag is 21.87% at 4 min and the basicity is 1.22 using limestone for slagging. With the blowing time increasing, the content of TFe reduces while the basicity increases to more than 3.0. Besides, the de-phosphorization process is much more stable and the dephosphorization ratio increases by 2.6%, and the average basicity of slag in the end is 3.52, meeting the demand of dephosphorization. Since the slag amount substantially reduces, which results in the decline of the consumption of steel material. The blowing time is prolonged and the temperature of liquid steel is kept constant. Furthermore, the re-sults also provide a new method and concept for optimizing the charging material structure and reducing the production cost.