Abstract: According to the law of mass action and the coexistence theory of slag structure, the distribution of manganese between MnO-FeO-SiO₂ and MgO-MnO-FeO-SiO₂ slag melts as well as liquid iron was analyzed. It is shown that K ′_Mn and K _Mno are only dependent on temperature and don't change with basicities and compositions of slag melts. So the distribution of manganese between the above mentioned slag melts and molten iron obeys the law of mass action. But analysis of experimental results from other sources shows that K ′_Mn and K _Mno really change with basicities of slag, which is probably arisen from not approaching equilibrium under low basicity slag melts.

Key words:  manganese distribution; the law of mass action; the coexistence theory of slag structure; mass action concentration