Abstract: The desulfurization process when liquid iron dropped across slag using a double-deck crucible was simulated to study the effect of MgO and Al₂O₃ on the desulfurization capacity of slag and clarify the relationship between w(MgO)/w(Al₂O₃) ratio and sulfur content in slag system. The results confirmed that desulfurization capacity increases gradually when the content of MgO increases from 6% to 12%， while further increases MgO content from 12% to 14% leading to the decrease of desulfurization capacity. The desulfurization capacity decreases slightly when Al₂O₃ content increases from 9% to 15%， while further increase of Al₂O₃ from 15% to 17% decreases the desulfurization capacity greatly. This study proposes that the desulfurization capacity of slag can be improved obviously by increasing w(MgO)/w(Al₂O₃) ratio when the content of MgO is less than 12% and content of Al₂O₃ is less than 15%.

Key words: blast furnace, slag, sulfide capacity, desulfurization capacity, w(MgO)/w(Al₂O₃) ratio