Increasing the Al₂O₃ content in the blast furnace slag, the blast furnace operations tend to make troubles such as excess accumulation of molten slag in the blast furnace hearth and increasing pressure drop at the lower part of the blast furnace. So, it will be important to keep good slag fluidity at the blast furnace operations such as, drainage of tapping and keeping good permeability.
In order to clarify the effect of high Al₂O₃ slag fluidity on the blast furnace, high Al₂O₃ slag (20%) test operations of experimental blast furnace have been carried out. Investigation results of the test operation are as follows;
1) Slag MgO improves the hearth drainage rate at high Al₂O₃ slag operation.
2) Permeability of the dripping zone is improved by decreasing slag CaO/SiO₂, at high Al₂O₃ slag operation of the blast furnace.
3) It was verified that the slag drainage phenomena were able to described by the fluid model.
4) The optimum composition of high Al₂O₃ slag of the blast furnace is high MgO and low CaO/SiO₂.