Manganese and silicon distribution between slag and metal in silicomanganese production

Laboratory measurements have been carried out to investigate the equilibriu m distribution of manganese and silicon between slag and metal in silicoman ganese production. Graphite crucibles have been used to study equilibrium b etween Mn-Si-C-sat alloys and MnQ-SiO2-CaO-Al2O3-MgO slags in CO gas at 1 6 00 degrees C, 1 650 degrees C and 1 700 degrees C. The equilibrium content of Si in the metal is mainly controlled by the temp erature, the silica content of the slag and the mass ratio R=(CaO+MgO)/Al2O 3. The silicon content increases with the temperature and the silica conten t, and decreases with increasing R-ratio. The silicon content remains appro ximately the same when some MgO replaces CaO in the slag. The equilibrium content of MnO in silicomanganese slags is primarily contro lled by the temperature and the silica content of the slag. Addition of Al2 O3 to acid slags will result in somewhat lower MnO contents, and addition t o 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.