2005 Volume 45 Issue 10 Pages 1439-1444
On facing the high productivity and elongation of life time in blast furnace iron-making, it is essential to protect the peripheral iron flow formed by a free space in the hearth in addition to maintaining the gas and liquid permeability of deadman. Therefore, it is important to stabilize the length of mud (tapping hole length) which is plugged and formed by hole closing refractory (mud materials), but the phenomena of fluctuation of tapping hole length are not clarified. In this paper, variables affecting the tapping hole length including the raceway depth measured by micro wave reflection struck tuyere are discussed under dimension analysis. As the burden weight above the raceway are balanced to upwind gas, the load to the hearth under the raceway is less than that in the furnace center and a high void ratio area or free space is easy to be formed under the raceway. As the result, it is clarified and quantified that the tapping hole length is recovered from shortage of distance by decreasing raceway depth which promotes deadman to sink further into bottom or increase the void ratio of peripheral area in the hearth.