Dephosphorization of Crude Stainless Steel with BaO-based Flux

Abstract

Dephosphorization of crude stainless steel with BaO-based flux is investigated in a laboratory scale test and industrial AOD operation.
By using BaO-BaCl₂-Cr₂O₃ flux or BaCO₃-BaCl₂-C flux of about 100 kg/t, 60% dephosphorization is possible, if the crude stainless steel has a chromium content of 16 to 25% and a carbon content of 1 to 2%. In addition, a more than 90% desulphurization and removal of vanadium can also be achieved.
To get satisfactory dephosphorization, Cr₂O₃ content in slag should be controlled in 3 to 6% with BaO content of 40 to 50%. Phosphate capacity of the slag ( C_PO4^3-≡(PO₄^3- ) /(P_P2^1/2·P_O2^5/4) ) is about 10²²⁷ at 1 450°C.
It is considered that this dephosphorization of crude stainless steel having a carbon content of 2% and a chromium content of 18% at 1 450°C proceeds with slightly higher oxygen potential of slag than that of metal.