The Melt-Down Properties of the Blast Furnace Burdens

The melt-down properties of the burdens is very important for operation of the blast furnace. For high efficiency and stabilization of the blast furnace operation, it seems desirable to use the burdens which melt down rapidly at high temperature in the blast furnace. A series of the experiments was carried out for clarifying the factors which govern the melt-down properties of the burdens, using various kinds of iron ores and agglomerates. 1) Melt-down behavior is closely related to amount and melting point of gangue and degree of pre-reduction. By the combination of these properties, either coagulation and fusion of slag formed from gangue or absorption of carbon in metal produced by reduction governs the melt-down behavior, and the temperature at beginning of melt-down is determined. 2) The burdens which have following properties melt down at high temperature and are desirable for the blast furnace operation. Lump ore: comparative large amount (100-200kg/t·Fe) and high melting temperature (>1600°C) of gangue. Acid pellet: high melting temperature of gangue (>1600°C). Sinter: basicity (CaO/SiO2) from 1.5 to 1.8. Self-fluxing and cold bond pellets: melting point of ganguc from 1500 to 1700°C.