Study on Reducing Dephosphorization of Hot Metal Containing Nb by CaC₂ Addition

A study on reducing dephosphorization of Nb-bearing hot metal by adding CaC₂ was carried out with carbon contents in the hot metal of 0.5% to 1.9%,and hot metal's temperature of 1 550℃.Effects of the amount of dephosphorizing agent added and its adding way,the carbon content in the hot melt,and the crucible material on dephosphorization rate were investigated.To improve the dynamics condition of hot metal,a new adding way that the dephosphorization agent was added into the hot metal's interior through a steel pipe was adopted according to characteristics of CaC₂ decomposition.The experimental results show that as the carbon content in molten steel decreases to 0.5% from 1.9%,the dephosphorization rate increases to 41% from 25%,which indicates the dephosphorization rate decreases with the increase of carbon content in molten steel.The dephosphorization rate decreases when top feeding is used instead of embedded feeding.Since corrosion of Al₂O₃ refractory is found,MgO crucible instead of corundum crucible is suitable for reducing dephosphorizatin with CaC₂-CaF₂.The content of Nb in hot metal does not change during dephosphorization.