MANUFACTURE OF MEDIUM-LOW CARBON FERROMANGANESE

PURPOSE:To permit the through manufacturing of medium-low carbon ferromangenese from Mn ores, etc., at relatively low temp. at the time of subjecting the molten metal of high Cr ferromanganese by reduction refining to decarburization refining in a reaction vessel by treating it under prescribed process-conditions. CONSTITUTION:Mn/Fe of Mn ores at the time of reduction refining is regulated to >=4.5 and the above molten metal contg., by weight, 73 to 81% Mn and =1300 deg.C to blow an oxygen-contg. gas onto the bath face of the molten metal from an upper blowing lance. As for the feeding speed of the above gas, before the bath temp. reaches 1600 deg.C, the heating temp. per metal ton is regulated to >=6.0 deg.C/Nm O2, and during this blowing time, the slag structure is retained to (MnO)/{(MnO)+(CaO)+(SiO2)}>=0.8. When the bath temp. rises to 1600 deg.C or above, the above feeding speed is regulated to