Phase equilibria in high MgO ferro-manganese and silico-manganese smelting slags

Abstract

Liquidus isotherms and phase equilibria have been determined experimentally for a pseudo-ternary section of the form "MnO"-(CaO+MgO)-(SiO 2+Al2O3) with a fixed Al2O 3/SiO2 weight ratio of 0.17 and MgO/CaO weight ratio of 0.17 for temperatures in the range 1 473-1 673 K. The primary phase fields present for the section investigated include manganosite (Mn,Mg,Ca)O; dicalcium silicate α-2(Ca,Mg,Mn)O middot; SiO2; merwinite 3CaO · ((Mg,Mn)O · 2SiO2; wollastonite [(Ca,Mg,Mn)O · SiO 2]; diopside[(CaO,MgO,MnO,Al2O3) · SiO2];tridymite (SiO2); tephroite [2(Mn,Mg)O · SiO2]; rhodonite [(Mn,Mg)O · SiO2] and melilite [2CaO · (MgO,MnO,Al2O3) · 2(SiO 2,Al2O3)]. The liquidus temperatures relevant to ferro-manganese and silico-manganese smelting slags have been determined. The liquidus temperature is shown to be principally dependent on the modified basicity weight ratio (CaO+MgO)/(SiO2+Al2O3) at low MnO concentrations, and dependent on the mole ratio (CaO+ MgO+MnO)/(SiO2+Al2O3) at higher MnO concentrations. © 2005 ISIJ.