Study on Reaction Mechanism of Reducing Dephosphorization of Fe-Ni-Si Melt by CaO-CaF₂ Slag

Abstract

In the present study, the dephosphorization of Fe-Ni-Si melt by CaO-saturated CaO-CaF₂ slag was investigated, from which it was found that the dephosphorization efficiency increases as increasing the silicon content, meanwhile the increase rate becomes rapid when the silicon content is more than 10 mass pct. By analyzing the phase compositions of the dephosphorization slag of a high silicon Fe-Ni-Si melt, it was first found the dephosphorization products change with the silicon content. When Si contents are 10.5, 31.48, 34.71, and 43.15 mass pct, the de-P products are Ca₂P₂, Ca_10+x Si_12−2x P₁₆, Ca₄SiP₄, and Ca_10+x Si_12−2x P₁₆, as well as Ca₄SiP₄, respectively. The corresponding dephosphorization mechanism can be described as $(2x)({\text{CaO}}) + (x + 2y)[{\text{Si}}] + 2z[{\text{P}}] = x({\text{SiO}}_{2} ) + 2({\text{Ca}}_{x} {\text{Si}}_{y} {\text{P}}_{z} )$.