Removal of P and Cr by Oxidation Refining of Fe-36%Ni Melt.

Abstract

Removal of P and Cr, which are impurities in a Fe-36%Ni alloy, was investigated by conducting experiments 30 kg scale on oxidation refining of a 36% Ni melt containing 0.1 mass% P and 0.4-1.5 mass% Cr with a CaO-SiO2-CaF2-FetO slag. FeCr2O4 was identified of X-ray diffraction analysis of water-cooled slag sample just after the experiments. Therefore, the oxygen potential of the dephosphorization reaction was taken to be controlled by the formation reaction of FeCr2O4. The removal reaction of P and Cr occurred along the P-Cr equilibrium (Eq. (A)), and consequently high temperature treatment was effective in lowering the P content in the range of the present Cr contents.2[P]+5/4FeCr2O4(s)=(P2O5)(l)+5/4Fe(l)+5/2[Cr] (A)The phosphorus distribution ratio (LP) decreased with increasing Cr content in the metal. This was considered because the oxygen partial pressure was lowered by increasing the content of Cr. In addition, LP increased with increasing in Ni content in the metal. It was concluded that this was because the oxygen partial pressure was increased with increasing Ni content mainly.