Thermodynamics of MnO, FeO, and phosphorus in steelmaking slags with high MnO contents

Abstract

The thermodynamics of manganese oxide and iron oxide and the phosphate capacity of CaO-SiO 2 -MnO-Fe t O-P 2 O 5 -MgO sat slags with high MnO contents relevant to the smelting of MnO ores in steelmaking were investigated. Previous data were limited to about 5 pct MnO, whereas in this study MnO contents up to 25 pct were studied. The activity of MnO showed positive deviation from ideal behavior and increased with basicity, while that of Fe t O decreased with basicity. This is reflected in that the manganese distribution ratio at a given Fe t O content decreases with basicity and high Mn in the metal is favored by high basicity. CaF 2 additions up to 4 pct did not affect the activities of MnO and Fe t O. The activity coefficient of P 2 O 5 decreases and the phosphate capacity increases with basicity. There was not adverse effect of high MnO contents on the dephosphorizing abilities of the slags.

Manganese and Chromium Distribution between CaO–SiO2–MgOsat.–CrO1.5–MnO Slags and Fe–Cr–Mn Stainless Steel

“…With increasing slag basicity, L Mn decreases, and thus the Mn content in the steel phase increases. This observation is in agreement with the data reported by Morales and Fruehan, 18) and Jung et al 36) on the Mn equilibrium between liquid iron and CaO-SiO 2 -MgO sat. -MnO-FeO t -P 2 O 5 slags at 1 873 K. The influence of slag basicity on L Mn indicates that MnO behaves as a basic oxide under the present conditions.…”

“…Figure 5 shows the variation of a MnO as a function of X MnO in the slags. Data from Morales and Fruehan 18) for CaO-SiO 2 -MgO sat. -MnO-FeO t -P 2 O 5 slags, and from Ding and Eric 16) for CaO-SiO 2 -MgO-MnO slags are also shown.…”

“…Mn and Cr losses can be minimized by the use of slags with high MnO and CrO x activities at low concentrations of MnO and CrO x . Many studies have been reported on the thermodynamics of the individual Mn [7][8][9][10][11][12][13][14][15][16][17][18][19] and Cr [20][21][22][23][24][25][26] equilibria. There are many data available on the MnO activity in the MnO-SiO 2 7) and the MnO-FeO 8,9) binaries, in the CaOSiO 2 -MnO 10,11) and the FeO-MnO-MO x (MO x ϭSiO 2 , Al 2 O 3 ) [12][13][14] ternaries, in the FeO-MnO-MgO-SiO 2 , 15) MnO-CaO-MgO-SiO 2 16) and MnO-SiO 2 -CaO-Al 2 O 3 17) quaternaries, in multi-component steelmaking slags (CaOSiO 2 -MnO-Fe t O-P 2 O 5 -MgO sat.…”

“…There are many data available on the MnO activity in the MnO-SiO 2 7) and the MnO-FeO 8,9) binaries, in the CaOSiO 2 -MnO 10,11) and the FeO-MnO-MO x (MO x ϭSiO 2 , Al 2 O 3 ) [12][13][14] ternaries, in the FeO-MnO-MgO-SiO 2 , 15) MnO-CaO-MgO-SiO 2 16) and MnO-SiO 2 -CaO-Al 2 O 3 17) quaternaries, in multi-component steelmaking slags (CaOSiO 2 -MnO-Fe t O-P 2 O 5 -MgO sat. ), 18) and in ferromanganese smelting slags, 19) under different oxygen partial pressures (10…”

Solubility of MgO in New Ironmaking Process-typed Slags

“…As results, growing concerns are expressed over the lime-based slags containing significant amount of manganese oxide. [2][3][4][5] For smelting reduction of Mn ore in the COREX process, it is necessary to understand the operating and thermodynamic conditions of respective iron and steelmaking processes, as well as the behavior of MnO in slag.…”