Manganese and Silicon Distribution between Slag and Metal in Silicomanganese Production

Abstract

Laboratory measurements have been carried out to investigate the equilibrium distribution of manganese and silicon between slag and metal in silicomanganese production. Graphite crucibles have been used to study equilibrium between Mn–Si–C_sat alloys and MnO–SiO₂ –CaO–Al₂O₃–MgO slags in CO gas at 1600°C, 1650°C and 1700°C.
The equilibrium content of Si in the metal is mainly controlled by the temperature, the silica content of the slag and the mass ratio R=(CaO+MgO)/Al₂O₃ . The silicon content increases with the temperature and the silica content, and decreases with increasing R-ratio. The silicon content remains approximately the same when some MgO replaces CaO in the slag.
The equilibrium content of MnO in silicomanganese slags is primarily controlled by the temperature and the silica content of the slag. Addition of Al₂O₃ to acid slags will result in somewhat lower MnO contents, and addition to more basic slags has the opposite effect. The equilibrium content of MnO in the slag is slightly increased when some CaO is replaced by MgO.