SynopsisThe previous results on manganese distribution between liquid iron and FetO-containing slaps have been summarized. The apparent equilibrium constant KMn=NMno/(NFeto' [%Mn]) in the FetO-MnO slaps can be expressed as log KMn = 7 572/T-3.599The variations of KMn with slag compositions in the FetO-MnOMOx (MOx=PO2 .5, Si02, A101,5, MgO, Ca0) ternary melts have been discussed on the basis of the regular solution model and the Richardson's model of ideal silicate mixing.