High Temperature Phase Relations in FeO<I><SUB>X</SUB></I>(<I>X</I>=1 and 1.33)–CaO–SiO<SUB>2</SUB> Systems under Various Oxygen Partial Pressure

Abstract

As a fundamental study of slags in metallurgical processes, liquidus lines in the FeO(wustite)-CaO-SiO 2 and Fe 3 O 4 (spinel)-CaO-SiO 2 systems were determined at temperatures between 1573 and 1673 K and partial pressures of oxygen between 10 - 4 and 36Pa using a quenching method with a crucible of platinum foil. It was found that the two phases (solid wustite and liquid) region in the FeO-CaO-SiO 2 system (1573 K) increased remarkably by changing the partial pressure of oxygen from 10 - 4 to 10 - 3 Pa. It was also found that the two phases (solid spinel and liquid) region in the Fe 3 O 4 -CaO-SiO 2 system (1573 K) at PO 2 of 10 - 2 Pa was a little larger than that in the FeO-CaO-SiO 2 system at PO 2 of 10 - 3 Pa but it was extended considerably when the oxygen pressure was increased to 10 - 1 Pa. However, the two liquids region did no change too much in the range of oxygen pressure above 10 - 1 Pa even though the liquidus line became almost parallel to the Fe 3 O 4 -CaO axis in the ternary diagram when the oxygen pressure was increased. Furthermore, it was found that the two phase region in the Fe 3 O 4 -CaO-SiO 2 system at PO 2 of 10 - 1 Pa decreased remarkably with increasing temperature. On the basis of the obtained and reported data, the homogeneous liquid regions in the FeO x -CaO-Si0 2 systems (1573K) at PO 2 of 10 - 3 Pa, 10 - 1 Pa and in air were compared.