涟钢RH-MFB精炼过程氮的行为研究

Nitrogen behavior in RH-MFB refining process at Lianyuan Steel

通过对真空钢液脱氮的限制性环节进行分析,结合涟钢RH-MFB实际生产情况,以确定涟钢RH-MFB脱氮的控制性环节及脱氮模型方程,并对影响钢液脱氮的因素进行分析。结果表明,涟钢RH脱氮的控制性环节为氮在液相边界层中的扩散,反应为一级反应;在工作真空度(67 Pa)下保持必要的钢水循环时间,有助于钢液脱氮;在深脱氧之后,钢液中氧的含量对脱氮的影响较小,而钢液中硫的含量一直较低,对脱氮的影响不大;钢液中碳含量的急剧下降带动了脱氮反应的进行,导致脱氮速率较大,当钢液中碳含量稳定后,钢液内的界面反应和吹氩对脱氮起主要作用。

By analyzing the restrictive step of nitrogen removal in molten steel during vacuum smelting and in light of the actual production of RH-MFB at Lianyuan Steel, the key steps and denitrogenation model equation in RH-MFB of Lianyuan Steel are determined; meanwhile, factors that influence nitrogen removal from liquid steel are analyzed. The results show that nitrogen diffusion in liquid phase boundary layer is the restrictive link of nitrogen removal in RH-MFB of Lianyuan Steel and yet the reaction follows first order kinetics. Sufficient circulation time under the working pressure（67Pa） is helpful to steel denitrogenation. After deep deoxidation, the oxygen content in molten steel has little influence on nitrogen removal. As the sulphur content in liquid steel is always relatively low, it has little effect on denitrogenation. The sharp decrease of carbon content in steel drives the process of denitrogenation reaction so that there is a faster denitrogenation rate. The interfacial reaction and argon blowing play a major role in the nitrogen desorption when the carbon content in liquid steel is stable.