DESILICONIZATION FOR FERROMANGANESE MELT AND ITS OXYGEN POTENTIAL IN DESILICONIZATION PROCESS

Experimental measurements of oxygen potential in liquid Mn of Mn-MnO2 equlibrium system (1350 ℃ ) show that ZrO2 (MgO) solid eletrolyte oxygen probe can be used to measure the oxygen potential in liquid Mn and ferromanganese melts. The relation between oxygen potential and electromotive force is in po2=31.56-(69548.8+46427.7× E)/T When BaCO370%-MnO25% (Fe2O3+BaF2)25% fluxes are used to desiliconize for blast furnace ferromanganese, the maximum desiliconization rate(75%) corresponds to Fe2O312% in flux,the relations between the oxygen potential in ferromanganese melt and carbon activity as well as manganese loss ( [Mn]) in the melt are po2 × 1012=35.812-0.106 ac and po2 × 10126.238+0.679 × [Mn] respectively. When blast furnace ferromanganese is desiliconized by BaCO360%-BaF210%-MnO215%-Fe2O315% fluxes, the maximum desiliconization rate (88.9%) and the highest oxygen potential in ferromanganese melt correspond to 15 min treatment. The results of desiliconization experiments show that the oxygen potential in ferromanganese melt is controlled by carbon-oxygen reaction in the melt. In order to desiliconize for ferromanganese and to prevent manganese from oxidation the oxygen potential in ferromanganese melt has to be controlled at or under 6.238× 10-12 Pa.