A sulphide capacity prediction model of CaO-SiO2-MgO-Al2O3 slags has been developed based on the ion and molecule coexistence theory(IMCT). Sulphide capacity(Cs) slag for blast furnace (BF) with high Al2O3 in system at 1773K were measured by applying slag-metal equilibrium method. The feasibility IMCT is verified experiment. Effects R(w(CaO)/w(SiO2)), w(MgO)/w(Al2O3) w(Al2O3) discussed. There a...