Effect of Accumulation of Molten Slag and Iron at Blast Furnace Hearth on Gas Pressure Drop

In the lower part of the blast furnace, molten slag and iron accumulate in the coke packed bed and is drained from the tapping hole. However, if tapping rate is reduced, these melts accumulate and an increase in the gas pressure drop occurs. This leads to the furnace troubles such as raw materials hanging. In this paper, the cause of the increase in gas pressure drop by the accumulation of melt was clarified phenomenologically using experiments of cold model and numerical simulation. As the result, it was proven that the gas flow region shrinks due to the accumulation of the melt, and the gas flow velocity near the tuyere increases. In addition, a numerical simulation of an actual blast furnace showed that gas pressure drop increased rapidly when average liquid level was within 1 m from the tuyere. If average liquid level increases to the vicinity of the tuyere, the shape of molten slag surface changes by gas pressure gradient, and liquid level on the tuyere side descends. In other words, when gas pressure drop due to the accumulation of molten slag is rapidly increased in the actual blast furnace, it is preferable to reduce the blast volume and increase the amount of tapping rate as soon as possible.