Improvement of Dephosphorization of Hot Metal by Preventing Rephosphorization from CaO-based Slag

Abstract

In order to improve dephosphorization, rephosphorization behavior of hot metal which contacts with CaO-Fe_tO-SiO₂-CaF₂-P₂O₅ slag has been studied at 1350°C.
The results obtained in this work are summarized as follows ;
1) The rate of rephosphorization in Ar proceeds faster than that in air.
2) The content of (Fe_tO) in slag required to prevent rephosphorization is about 1% for slag with CaO/SiO₂ of 4.66, and is about 2-3% for slag with CaO/SiO₂ of 2.51.
3) In dephosphorization process using injection method, addition of iron oxide to top slag, which increase (Fe_tO) contents in slag, is quite important for improving dephosphorization.
4) In dephosphorization of hot metal, the value of (T. Fe) is not available for index of oxygen potential in slag. Because the slag contains much iron particle with micron size. Therefore, the particle must be removed chemically before analyzing.